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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , Page No., Nature and Scope of Biology, , ♂░▀♀–σ∟–▼▀♠◄☻☼▀♀♦–▒◘–▌▀◘◄–, 1. Systematics, 2. Viruses, 3. Kingdom Monera, 4. Kingdom Protista, 5. Fungi, Lichen and Mycorrhiza, ♂░▀♀–τ–∟–█▀░◙▼▒▐–▓▌○░♀○◄–, 6. Plant Classification, 7. Algae, 8. Bryophyta, 9. Pteridophyta, 10. Gymnosperms, 11. Angiosperms, ♂░▀♀–φ–∟–█▀░◙▼▒▐–○░▀▐○▌▀○–, 12. Evolutionary Trends & Classification of Animals, 13. Protozoa, 14. Non-Chordates, 15. Chordates, , vi, , σ– –φφ, 1, 7, 11, 20, 24, φ←– –↓τ, 34, 36, 43, 47, 52, 60, ↓φ– –στ↨, 63, 71, 79, 106, , ♂░▀♀–←–∟–►◄▌▌–▲▀▒▌▒◙♦–, 16. Tools and Techniques in Cytology, 17. Cell as a Unit of Life, 18. Biomembrane, 19. Structural Organization of Cell, 20. Biomolecules, 21. Enzymes, 22. Cellular Metabolism, 23. Cell Reproduction, , σφε– –τσε, 130, 137, 145, 153, 170, 182, 188, 200, , ♂░▀♀–↑–∟–◄♠▒▌♂♀▀▒░–, 24. Origin of Life, 25. Relationship Among Organisms and Evidences of Evolution, 26. Theories of Evolution, 27. Human Evolution, , τσσ– –τφ↨, 211, 216, 225, 234, , ♂░▀♀–↓–∟–☼♀☻♂►♀♂☻○▌–○░▼–▒☻◙○░▀☼○♀▀▒░–▀░–▓▌○░♀☼–○░▼–○░▀▐○▌☼–, 28. Plant Taxonomy, 29. Morphology of Flowering Plants, 30. Anatomy of Flowering Plants, 31. Animal Tissue, 32. Integumentary System, 33. Morphology and Anatomy of Animals (Frog, Cockroach, Rabbit, Earthworm), , τ←ε– –φτε, 240, 245, 270, 282, 298, 303, , ♂░▀♀– –↔–∟–▓▌○░♀–▓Ř♦☼▀▒▌▒◙♦–, 34. Water Relations of Plants, , φτσ– –φ↓τ, 321
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ŕďőĽę– ĐĽŐńŐĹť, , 35. Mineral Nutrition in Plants, 36. Photosynthesis, 37. Respiration in Plants, , v, , 332, 342, 352, , ♂░▀♀– –↕–∟–Ř♂▐○░–▓Ř♦☼▀▒▌▒◙♦–, 38. Nutrition & Digestive System, 39. Breathing & Exchange of Gases, 40. Locomotion and Movement, 41. Body Fluids and Circulation, 42. Excretory System, 43. Nervous System, 44. Sense Organs, 45. Endocrine System, , φ↓φ– –←←φ, 363, 377, 384, 392, 401, 410, 419, 428, , ♂░▀♀– –↨–∟–☻◄▓☻▒▼♂►♀▀▒░Θ–▼◄♠◄▌▒▓▐◄░♀–○░▼–◙☻▒♣♀Ř–, 46. Reproduction in Flowering Plants, 47. Plant Growth and Movement, 48. Phytohormones, 49. Human Reproduction, 50. Embryonic Development, 51. Growth, Repair, Regeneration, Ageing & Death, , ←←←– –←↕↨, 444, 455, 463, 469, 478, 486, , ♂░▀♀– –σε–∟–◙◄░◄♀▀►☼–, 52. Heredity and Variation, 53. Genes & Chromosomes, 54. Genetic Material & Protein Synthesis, 55. Gene Expression & Regulation, 56. Human Genetics and its Disorders, , ←↨ε– –↑τ↕, 490, 498, 509, 518, 524, , ♂░▀♀– –σσ∟–◄►▒▌▒◙♦–○░▼–◄░♠▀☻▒░▐◄░♀–, 57. Organisms and Environment, 58. Population, Biotic Community & Succession, 59. Ecosystem, 60. Natural Resources and Their Conservation, 61. Biodiversity, 62. Pollution & Global Environmental Changes, 63. Wildlife and Conservation, ♂░▀♀– –στ–∟–○▓▓▌▀◄▼–▲▀▒▌▒◙♦–, 64. Biotechnology and Genetic Engineering, 65. Domestication of Plants and Crop Improvement, 66. Plant Tissue Culture, 67. Economic Botany, 68. Plant Pathology, 69. Pesticides and Biofertilizers, 70. Mental health, Addiction and Community health, 71. Immune System & Defence Mechanisms, 72. Common Human Diseases, 73. Biomedical Technologies, 74. Domestication and Improvement of Animals, 75. Animal Behaviour, 76. Bioenergy, 77. Growth of Human Population, , ↑τ↨– ↑↔↓, 529, 536, 542, 548, 557, 562, 570, ↑↔↔– –↓↨↨, 577, 589, 599, 606, 616, 622, 630, 635, 646, 661, 672, 687, 692, 695
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, vi, , ŕďőĽę– ĐĽŐńŐĹť, , WHAT IS BIOLOGY, Biology, the word comes from Greek bios meaning life and logos meaning thought or science of, can be defined, as the study of various aspects of living beings (plants and animals). Biology is the study of life from the simplest, forms of plants and animals (including onecelled animals and algae) to highly complex structures of the human, being. It includes the study of how organisms are structured as well as how they function and relate to each other., Biology is also called life science as it makes to understand how living things perform their life activities and, interacts with the other living and nonliving things. Main branches of biology are botany, zoology and microbiology., Pure biology is concerned with gaining fundamental knowledge of the subject and studied only for better, understanding of natural phenomenon. It has no direct practical application in human welfare, eg. taxonomy,, physiology etc. Applied biology is related to well being of mankind and is directly beneficial economically. Some, of the main branches of applied biology are agriculture, animal husbandary, sericulture, poultry, genetic engineering,, breeding, biotechnology, bioinformatics etc., Table : Branches of biology, Branch of Biology, Agriculture, Horticulture, Apiculture, Sericulture, Anthropology, Entomology, Medicine, Agronomy, Soil Science, Breeding, Veterinary Medicine, Fishery, Poultry Science, Forestry, Dairy Technology, Microbiology, Pharmacy, Pharmacology, , Definitions, The study of how best to grow and improve crops., Development and management of orchards and gardens., The rearing of bees especially for commercial purpose., The breeding and treatment of silkworms for raw silk., The study of physical and mental constitution of man with social conditions, exhibited both in the present and the past., The study of insects., The study of structure and functioning of the human body and mind in sickness, and health., Branch of agricultural science which deals with the study of crops and soils., Study of structure, types and dynamics of the soil., To produce or procreate improved varieties by selective mating., Deals with the diseases of domesticated animals and their health care., Occupation or industry of catching fish or other products of the sea, lakes or, rivers., Deals with study of domestic fowls such as chickens, ducks and geese., Science of developing, cultivation and conserving forests., Application of science for the manufacture of milk products., Science that deals with the structure, function, uses etc. of microscopic organisms., Science that deals with preparing and compounding medicines and dispensing, them according to the medical prescriptions., Science that deals with the knowledge of drugs and preparation of medicines.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ĐĽŐńŐĹť, ░ŕĚ–ŕďőĽę–, ·– ☼ĘŐőĚ–, Őě– ▲ĽŐńŐĹť, Forensic Science, Surgery, Human Reproductive Biology, Nutrition, Physiotherapy, Occupational Therapy, Genetic Engineering, Biomedical Engineering, Food Technology, Silviculture, Olericulture, Anatomy, Biochemistry, Biogeography, Cytology, Ecology, Embryology, Endocrinology, Evolution, Eugenics, Exobiology, Genetics, Histology, Immunology, Limnobiology, Morphology, Molecular biology, Palaeontology, Palaeozoology/Palaeobotany, Physiology, Psychology, Parasitology, Pathology, Radiobiology, Taxonomy, Teratology, Zoogeography, Zoopathology, , vii, , Application of scientific knowledge to questions of civil and criminal law, (includes use of fingerprints, blood typing, identification of narcotics etc)., Surgery involves physical operations to cure diseases or injuries to the body., Science of understanding and regulating reproduction., Study of the nourishment of human beings or other organisms., Science of treatment of diseases, bodily weaknesses or defects by physical, remedies such as massage and exercise., A method of treatment of convalescents and the physically handicapped, utilising light work for diversion, physical exercise or vocational training., Science that involves manipulations at gene level so as to produce an organism, with a new combination of inherited properties., Science for production of spare parts for man, implants, artificial limbs, heart, lung machines etc., Application of science for processing and preservation of foods., Management of useful forest., Cultivation of vegetables., Internal structures of living organisms., Science connected with chemistry (composition, chemical nature, mode of, formation, functioning) of living matter., Distribution of organisms on various parts of earth., Structure and functions of cells and their organelles., Relationship between organisms and environment., Development stages of organisms up to hatching or birth., Endocrine glands and hormones., Origin of life and the gradual differentiation or descent of species., Factors related to improvement of human race., Life on other planets., Heredity and variations., Tissues by microscopy., Resistance of organisms to infection., Fresh water lakes, ponds and streams., External shape of living organisms in contrast to function., Physiochemical organization of biomolecules., Fossils and their distribution in time., Fossil animals/fossil plants., Functions of various organs within the organisms., Behaviour and working of mind., Parasitic organisms., Diseases and their control., Effects of radioactivity on life., Classification of organisms and their evolutionary relationship with other, organisms., Malformation or birth defects., Distribution of animals over the earth., Diseases of animals.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, viii, , ŕďőĽę– ĐĽŐńŐĹť, , RELATIONSHIP OF BIOLOGY TO OTHER SCIENCE, In order of study biology one has to understand and know other sciences like physics and chemistry as well. Because, our present knowledge of biology has reached to such an extent that it has become a multidisciplinary branch of, science involving participation of the fundamental knowledge of all the basic sciences., Structure/, Mechanism, Studied, , Example, , Related Science Knowledge of other sciences is required, because, , Cell membrane, , Structure of lipids,, and proteins, , Chemistry, , Living organisms are made up of inorganic and, organic compounds., , Transportation of, O2 in body, , Formation of, oxyhaemoglobin, , Chemistry, , All metabolic pathways involve chemical changes., , Excretory system, , Absorption and, elimination of salts, , Chemistry, , Homeostasis involves acidbase equilibrium to, maintain pH of living organism., , Absorption of, food/water, , Absorption of sugars, amino acids, fatty, acids, water or salts, , Chemistry, , During diffusion and osmosis molecules move, in and out of cells., , Transportation of, water in plants, , Conduction of water, from root to leaves, , Physics, , Liquids have certain properties like cohesion and, adhesion that result in surface tension and, capillary action which help in certain processes., , Release of energy, during respiration, , Electron transport, chain, , Chemistry, , Energy transfer and transformation are important, in all the living cells., , Effect of light on, flowering, , Absorption of, different wave, lengths of light, , Physics, , Light induces definite pattern of responses in, plants and animals., , Similarly other branches also have relationship with Biology in their particular characters like –, l, Geography – Required for studying the distribution of organisms., l, Climatology – There is an intimate relationship between distribution and adaptations of organisms with the, climate of the area., l, Geology – Study of palaeobiology and soil types cannot be carried out without the knowledge of geology etc., , UTILITY OF STUDY OF BIOLOGY, The scope and application of biology is quite vast. Its study provides a necessary knowledge and perfect understanding, about almost all the spheres of life, its requirements and the various ways by which they can be fulfilled., Study of biology is connected with the following objectives., l, To help us to understand ourselves better. It explains the basic concepts like structure and functions of cells,, organs and organ systems. It explains about heredity i.e., why do we resemble our parents and why are we, different. It helps us to answer the basic questions about ourselves like what happens during sleep, when, we eat food, when we get hurt, and how do we remember things etc., l, To help us to meet our needs by utilising the sources available. The knowledge of medicine, surgery, crops, rotation, animal husbandry help us to cure diseases and improve the quality of plants and animals. Meeting, our basic requirements of food, clothing and shelter., l, To acquaint us with the fundamentals of nutrition, health and population control. To have a scientific, approach while solving problems., l, To enlighten us about our place in the universe. It helps us to understand that man is only a small part of, the living system and we have a responsibility to protect and respect other living things on earth.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ĐĽŐńŐĹť–, ░ŕĚ–ŕďőĽę–, ·– ☼ĘŐőĚ–, Őě– ▲ĽŐńŐĹť, l, , l, , l, l, , ix, , To increase the awareness of the interrelationships of organism with the environment. It makes us aware, about the threat that lies before us if the natural resources are not taken care of. It helps us to identify, measures to overcome them., To warn us about health hazards due to indiscriminate use of pesticides, fertilizers, cutting of forests,, depletion of the ozone layer, dumping of radioactive wastes in water, discharge of pollutants in air and water, and wastage of our natural resources., To help us overcome the superstitions and to remove the biases of sex, race and colour., To enable us to enjoy nature and appreciate the rich, varied life of living things on earth., , BIOLOGY : SCIENCE OF EXCEPTIONS, Physical sciences are governed by a set of laws, such as the laws of gravity, magnetism, thermodynamics and, so on. Biology, however, is a science which have many exceptions. This is due to the fact that it deals with living, organisms which show enormous variations and are capable of change. Some of the common exceptions are given, below., Ü, DNA is the hereditary material in all living organisms except in some plant viruses such as Tobacco mosaic, virus where RNA is the hereditary material., Ü, RNA is usually single stranded but in Rheovirus it is double stranded., Ü, DNA is normally double stranded except in some viruses in which it is single stranded., Ü, Most roots grow towards the centre of gravity but in mangrove plants (Rhizophora) the roots are negatively, geotropic., Ü, Cuscuta (Amerbel) is classified as dicotyledonous plant but lacks cotyledons., Ü, Normally the roots lack chlorophyll and are nongreen but the assimilatory roots of Tinospora (Gilo) contain, chlorophyll, are green and perform the function of photosynthesis., Ü, The venation in monocot leaf is as a rule parallel but in Smilax (a monocot plant) the leaf show reticulate, venation., Ü, Stem is the part of plant above the ground but potato, corn and ginger are underground stems., Ü, Most plants follow Calvin cycle during dark phase of photosynthesis but sugarcane follows Hatch Slack, cycle., Ü, All living cells have a nucleus except red blood cells (RBC) of mammals., Ü, RBCs of mammals are without nucleus excepts those of camel., Ü, Blood of all vertebrates is red due to the presence of a pigmenthaemoglobin but in a shark (Carcharhinus), it is colourless., Ü, The heart of all reptiles is three chambered but in crocodile it is four chambered., Ü, Birds fly, but some birds like Kiwi and Ostrich are unable to do so., Ü, Lungs, as a rule are absent in fishes, but some fishes the Protopterus possess lungs as well as gills., Ü, Larval stage in the life history of an animal is not capable of sexual reproduction sexually before they change, into adults., Ü, All mammals give birth to young ones (viviparous) but some primitive mammals like Duck billed platypus, and spiny ant earter (Echidna) lay eggs (oviparous)., Ü, All land inhabiting animals drink water but Kangaroo rat never drinks water., Ü, Lacerta saxicola, a kind of lizard found in Caucasian region of Soviet Union has only females but no males., A student of biology must be prepared to accept exceptions. Some exceptions has been explained. In other cases, the reasons for the exceptions are still no known. It is worth noting that the quantum of unexplained phenomena, in biology is much larger than in any other natural science., , SERENDIPITY, Discoveries of important facts by chance unexpectedely, intuition and thoughts without making well planned, conscious effect are called serendipity.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, x, , ŕďőĽę– ĐĽŐńŐĹť, , Some of the examples of serendipity are –, Ü, Discovery of antibiotic – Penicillin : Alexander Fleming (18811955) was culturing the bacterium –, Staphylococcus (the causal organism infection) in Petri dishes on agar medium. He found that one of his, culture plate was contaminated by bluegreen mould – Penicillium notatum. Such a contamination in laboratories, was not new. Normally such contaminated cultures are discarded but Fleming retained it and observed, minutely. To his surprise, he noticed that fungal growth inhibited in those areas where fungus was growing., By flash idea Fleming poured the extract of fungus over fresh bacterial cultures and found that even the extract, inhibited the bacterial growth. This curious observation led the discovery of the most important antibiotic, – Penicillin., Ü, Law of Gravitation : Newton was simply sitting in the garden when an apple fell on the ground. He started, thinking about the cause of its fall and came to a conclusion that some force is present in the earth which, attracts everything towards it. This observation led the formation of Newton’s law of gravitation., Ü, Structure of Benzene ring : Chance observation of snake licking its tail led the discovery of ring – structure, of benzene by Kekule., Ü, Archimede’s Principle : While taking bath he came to the conclusion that a body which is immersed partially, or completely in a liquid, experiences an up thrust equal to the weight of the liquid displaced by it. This led, to the discovery of principle of floatation by Archimedes., Table : Fathers of Biology, Antibiotics, Ayurveda, Bacteriology, Biochemical genetics, Biochemistry, Biology, Blood circulation, Blood groups, Botany, Chromatography, Comparative anatomy, Cytology, ECG, Ecology, Embryology, Endocrinology, Eugenics, Experimental genetics, Gene Therapy, Genetic engineering, Genetics, , Alexander Fleming (1881, 1955), Charaka, Antony Van Leeuwenhoek, (16321723), Archibald Garrod, Justus vol Liebig (180373), Aristotle (384322 BC), William Harvey (15781657), Karl Landsteiner, Theophrastus (372287 BC), Micheal Tswett, Georges Cuvier (17691832), Robert Hooke (16351703), Einthoven, Theophrastus (370285 BC), Aristotle, Thomas Addison (17931860), Francis Galton, Thomas Hunt Morgan (1866, 1945), Anderson, Paul Berg, Gregor Johann Mendel, (18221884), , Histology, Homeopathy, Immunology, Indian palaeobotany, Medicine, Microbiology, Microbiology, Microscopic Anatomy, Microscopy, Modern embryology, Modern genetics, Modern palaeontology, Palaeontology, Parasitology, Protozoology, Science, Surgery, Taxonomy, Tissue culture, Virology, Zoology, , Xavier Bichat (17711802), Hahnemann (17551843), Edward Jenner, Birbal Sahni (18911949), Hippocrates (460377 BC), Antony Van Leeuwenhoek, Louis Pasteur (18221895), Marcello Malpighi (1628, 1694), Antony Van Leeuwenhoek, Von Baer (17921876), William Bateson (1861, 1926), Georges Cuvier (17691832), Leonardo da Vinci, Platter, Antony Van Leeuwenhoek, Aristotle, Susruta, Carolus Linnaeus (1707, 1778), Harrison, Wendell M. Stanley, Aristotle, , nn
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ťřŚĚŇĘř–, , 1, , Chapter 1, , Systematics, l, , l, l, , l, l, , l, , l, l, l, l, l, , l, , l, l, l, , l, , Systematics is the study of the historical, relationships of groups of biological organisms, – the recog nition an d un d erstan ding of, biodiversity., The term systematics was coined by Linnaeus, (1735)., The terms systematics, taxonomy and classification, are often held as synonyms but technically they, carry different meanings., G. Simpson (1961) has distinguished the three, terms., Taxonomy is the branch of study which deals with, identification, nomenclature and classification of, organisms., Term taxonomy was first given by French botanist, A.P. de Candolle (17781841) for the theory of, plant classification., Taxonomy is also called systematic botany., Carolus Linnaeus is called father of taxonomy., H. Santapau is called the father of Indian, taxonomy., Taxonomy is of three types – alpha (a) taxonomy,, beta (b) taxonomy and omega (w) taxonomy., When only morphological characters are used for, identification and classification of plants then it is, called alpha taxonomy., btaxonomy involves genetical, anatomical, cytological, palynological, physiological and, other characters., btaxonomy is also called biosystematics., a and b taxonomy terms were given by Turill., Analysis and synthesis of all information and types, of data to develop classification system based on, phylogenetic relationships is called omega, taxonomy., Classification is the placing of an organism or a, , l, , l, , l, , l, , l, , l, , l, , l, , l, , group of organisms in category according to a, particular system and in conformity with a, nomenclature system., Aristotle (father of zoology) made the first, recorded attempt to classify the animals in his book, Historia Animalium., Aristotle made two main groups anaima (animals, with no RBC, invertebrates) and enaima (animals, with RBC, vertebrates)., Theophrastus (372 287 BC), referred to as father, of botany, classified plants on the basis of form, and texture and described 480 plants in his book, Historia Planatarum., Identification is to determine the exact place or, position of an organism in the set plan of, classification. Identification is carried out with, the help of taxonomic keys., A key provides a convenient way for easy, identification of an organism by applying, diagnostic or distinguishing characters., Taxonomy discovers and describes new species,, w hile s ys tematics use s ev olutionar y, relationships to understand biogeography,, coevolution, adaptation and options for biological, conservation., Systematists or taxonomists are thus the scientists, whose expertise provides the data about the, identification, description, distribution and, relationship of life on Earth., New systematics or biosystematics is concept of, systematics which brings about taxonomic affinity, on the basis of evolutionary genetic and, morphological traits., Julian Huxley (1940) proposed the term new, systematics.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 2, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Types of taxonomy, Cytotaxonomy, , l, , based on cytological study, , Karyotaxonomy based on nucleus, chromosomes, , and, , Morphotaxonomy based on morphological, characters, Biochemical, taxonomy, , based on biochemical studies, , Chemotaxonomy based on specific chemicals, like secondary metabolites, based on statistical methods, Numerical, taxonomy (also, called adansonian, taxonomy), Experimental, taxonomy, , based on experimental, determination of genetical inter, relationships and role of, environment in their formation, , l, l, l, , l, , l, , Nomenclature, l, , l, l, , l, , l, , l, l, l, , Nomenclature is giving distinct scientific names, to various structures including living organisms,, for their identification., Biological nomenclature is of two types , vernacular and scientific., Common names by which plants and animals are, known in their regional places are called vernacular, names., The vernacular name or common names are based, on some peculiarity of the organisms, eg. Kandiali, (a plant having spines)., Scientific name are names given to organisms based, on agreed principles and criteria for their, acceptability all over the world., Scientific names are distinct and specific, they have, particular spellings which are not changed., Three types of nomenclature are – polynomial,, trinomial and binomial nomenclature., Polynomial nomenclature was the first scientific, attempt at nomenclature, in which an organism, is given a name consisting number of words that, incorporate all its important characteristics. Eg., Caryophyllum saxatilis folis gramneus umbellatis, corymbis which means caryophyllum growing on, rocks, having grass like leaves and umbellate, corymb flowers., , l, , l, l, , l, , l, l, l, , Trinomial nomenclature is a taxonomic naming, system that extends the standard system of binomial, nomenclature by adding a third taxon. It is used in, biology when the organisms within a species fall, into separate groupings that need to be distinguished., Trinomial nomenclature is different for animals, and plants., In animals trinomen or trinominal name refers to, the name of a subspecies., Trinomen is a name consisting of three names –, generic name, specific name and subspecies, name. All three names are typeset in italics and, only the generic name is capitalised. Eg. Buteo, jamaicensis borealis is one of the subspecies of the, red tailed hawk (Buteo jamaicensis)., For plants trinomial nomenclature provides three, part name (ternary name) for any taxon below the, rank of species., Binomial nomenclature is a system of providing, distinct proper scientific names to organisms with, each name consisting of two words, generic and, specific., Binomial nomenclature was developed by Linnaeus, (a swedish biologist) who gave certain principles, (called Linnaean principles) for this in his book, Philosophica Botanica (1751). The standard, references recognised for this are Species Planatarum, (1733) and Systema Naturae (1758)., According to binomial system, each organism is, given a name made of two Latin words., For nomenclature the Latin language is used, because it is the dead language and no changes, are supposed to occur in it., Binomial system of nomenclature was introduced, by Gaspard Caspar Bauhin (1956). But he did, not follow it scrupulously., Binomial names are of universal application for, all the countries and languages., The names indicate relationship of a species with, others present in the same genus., In binomial nomenclature following rules are, applicable., –, Name consist of two words – first word, represents the genus and is called generic, name (generic epithet), whereas the second, word represents the species called the specific, name (specific epithet)., –, The generic epithet always starts with capital
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ťřŚĚŇĘř, , l, , l, , letters & specific epithet starts with small, letter., –, Both these name must be underlined separately, (if handwritten) or italised (if printed)., –, No comma, hyphen etc. between specific and, generic name is used., –, To the two word, name is appended the name, of taxonomist who discovered the organism, and provided with a scientific name, e.g., Ficus, bengalensis L, Homo sapiens L., –, The different names given to same species by, different workers are called synonyms, but, the name given first is considered to be valid., The foundations of International Code of, Botanical Nomenclature (ICBN) was found in, Philosophia Botanica, a book written by C., Linnaeus. Current code of botanical nomenclature, appeared in 1978., Botanical nomenclature is independent of, zoological and bacteriological nomenclature, which are governed by their own code., ICBN, ICZN, ICBacN, ICVN, ICNCP, , Some important abbreviation, – International code of botanical, nomenclature, – International code of zoological, nomenclature, – International code of bacteriological, nomenclature, – International code of viral, nomenclature, – International code of nomenclature, for cultivation plants, , Types of specification, l, , l, , l, , l, , The particular illustration designed by author of, the species to represent the type of species is called, holotype., A specimen which is a duplicate of the holotype,, collected from the same place, same time and by, the same person is called isotype., Any one of the two or more specimens cited by the, author when no holotype was designated, or any, one of the two or more specimens simultaneously, designated as types is called syntype., A paratype is a specimen cited in the protologue, that is neither the holotype nor an isotype, nor one, of the syntypes if two or more specimens were, simultaneously designated as types., , l, , l, l, , l, , l, , l, , 3, , A specimen or other element selected from the, original material cited by the author when no, holotype was originally selected or when it no, longer exists is called lectotype., A lectotype is selected from isotypes, paratypes, or syntypes., A specimen or illustration selected to serve as, nomenclatural types as long as all of the material, on which the name of the taxon was based is missing, is called neotype., Epitype is a specimen or illustration selected to, serve as an interpretative type when the holotype,, lectotype or previously designated neotype, or all, original material associated with a validly published, name is demonstrably ambiguous and cannot be, critically identified for purposes of the precise, application of the name of a taxon., Topotype is often the name given to a specimen, collected from the same locality from which the, holotype was originally collected., When many names are given to the same species,, then the name under which the species was first, described is valid, provided the publication is, effective and valid., , Taxonomic hierarchy or Linnaean hierarchy, l, , l, l, l, , l, l, l, l, l, l, , Taxonomic hierarchy is the sequence of, arrangements of taxonomic categories in a, descending order during the classification of an, organism., The word taxa represents taxonomic groups of any, rank i.e. any unit of classification., In Linnaean hierarchy, the number of taxa is five,, namely – class, order, genus, species and variety., The rank of species is basic and relative order of, the rank of taxa are species, genus, tribe, family,, order, series, class, division (= phylum) and, kingdom., These categories/rank are ranked one over the other, called ‘hierarchy’., Kingdom is the highest and species is the lowest, category in this hierarchy., Species is the basic unit of taxonomy., John Ray introduced the term animal species., Species inhabiting the same geographical area, (identical or overlapping) are sympatric., Species inhabiting different geographical areas are, allopatric.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 4, , l, l, l, l, , l, , l, l, l, l, , l, , l, , l, l, l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Related species which are reproductively isolated, but morphologically similar are called sibling species., A species restricted to a given area is called endemic, species., Classical systematics is based on the ‘typological, concept’ by Plato and Aristotle., The traditional concept of species was given by, Linnaeus in Systema Naturae; this is based on, morphology, and is also known as ‘morphological, concept’., Genetic species concept was given by Lotsy, (1918), according to which, a species is a group, of genetically identical individuals., Species that contain two or more subspecies are, called polytypic species., Species that are not subdivided into subspecies are, called monotypic species., Modern concept of species is biological species, concept introduced by Ernst Mayr (1942)., Mayr defined species as groups of interbreeding, natural populations that are reproductively isolated, from each other group., Genus is an assembly of related species which, evolved from a common ancestor and have certain, common characters called correlated characters,, e.g., Solanum tuberosum and Solanum melongena, are two species which belong to same genus of, Solanum., A family subdivision of an order consists of a group, of closely related genera, which in turn are, composed of groups of closely related species., The taxon commonly encountered in routine, taxonomic work is the family., Family with a single genus is called monogeneric, family., An order is a category within a class. Carnivora, is an order of flesheating animals within the class, mammalia and there are several other orders of, mammals like cattle, rodents, bats, seals,, whales, etc., A class is a subdivision within a phylum made of, one or more related orders, for e.g., within the, phylum chordata there are five classes: mammals,, birds, reptiles, amphibians and fishes., Georges Leopold Cuvier (17691832), the French, naturalist, added the ‘phylum’ in taxonomy., In taxonomy, the correct sequence is: class , order family tribe genus species., , l, l, l, , l, , l, , Microbiologists and botanists (Eichler) use the term, ‘division’ instead of ‘phylum’., All kingdoms have more than one phylum., The kingdom plantae contains several divisions, (=phyla), including flowering plants, conifer trees,, mosses, ferns and several other groups., Taxonomic hierarchy is useful in that it provides, information about relationships of an organism, with others quick identification of a taxon, all, major traits and nonrepetition of correlated traits, of various categories., According to ICBN different ranks or categories, have following specific ‘endings’ (Refer table given, below)., Ranks, , Plants, , Algae, , Fungi, , Division/, Phylum, , phyta, , mycota, , Subdivision/, subphylum, , phytina, , mycotina, , Class, , opsida phyceae mycetes, , Subclass, , idae, , Superorder, Order, , Animal, , phycidae mycetidae, , anae, ales, , Infraorder, , ineae, aria, , Superfamily, , acea, , oidea, , Family, , aceae, , idae, , Subfamily, , ordeae, eae, , inae, , Tribe, Subtribe, , inae, , ina, , Suborder, , ini, , Table : Taxonomic status of human & pea, , Rank, Domain, Kingdom, Phylum or Division, Subphylum or, Subdivision, Class, Subclass, Order, Suborder, Family, Subfamily, Genus, Species, , Human, Eukarya, Animalia, Chordata, Vertebrata, , Pea, Eukarya, Plantae, Magnoliophyta, Magnoliophytina, , Mammalia, Placentalia, Primates, Haplorrhini, Hominidae, Homininae, Homo, H. sapiens, , Magnoliopsida, Magnoliidae, Fabales, Fabineae, Fabaceae, Faboideae, Pisum, P. sativum
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 5, , ☼ťřŚĚŇĘř, , System of biological classification, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , There are four different systems of classification,, mainly used by taxonomists. They are (i) artificial,, (ii) natural, (iii) phylogenetic, and (iv) phenetic., A classification based on one or a few superficial, similarities is called an artificial system of, classification., Artificial system of classification was adopted by, Pliny the Elder (first century AD) for animals on, the basis of habitats, e.g., land, air and water., The plants are classified on the basis of habit into, (i) herbs, (ii) undershrubs, (iii) shrubs, (iv) trees in, an artificial classification., The Linnaean system of classification of plants on, the basis of number and arrangement of stamens, is artificial. Linnaeus used number, union, length, and certain other characters of stamens as the basis, of classification of plants in his book ‘Genera, Planatarum’ (1737)., In natural systems of classification organisms are, arranged according to their natural affinities through, the use of all important permanent characteristics,, especially structural, cytological (chromosomal), reproductive and biochemical., The first natural system of plant classification, was proposed by Schimper (1879) followed by, Eichler (1833)., The most important and last of natural systems, for classification of seed plants was developed, by Bentham (1800–1884) and Hooker (1817–, 1911) in the treatise called Genera Planatarum, (1862–1883)., The first natural system of animal classification, was developed by Linnaeus in his book “Systema, Naturae”. Improvements were subsequently made, by Haeckel (1864) and Lankester (1874)., The classification based on evolutionary sequence, and the genetic relationships among the, organisms is termed phylogenetic system., Darwin’s book “On the Origin of Species by, Means of Natural Selection” (1859) provided, support to taxonomy., The phylogenetic classification of the plant, kingdom was proposed by Adolf Engler (1844–, 1930) and his associate Karl Prantl (1849–1893), in their book Die Natürlichen Pflanzen Familien., , l, , l, , l, , l, , l, , l, l, , l, l, , In this system, flowering plants are placed in, ascending series related to complexity of floral, morphology., This classification was also adopted by the English, botanist John Hutchinson (1884–1972) in two, volumes of his book “Families of Flowering, Plants”., “Taxonomy without phylogeny is similar to bones, without flesh” is the statement of A.L. Takhtajan, (1967) who wrote the book “A system of, phylogeny of flowering plants”., According to zoologists, the natural system of, classification includes the phylogenetic and, evolutionary trends., A modern method of classification called cladistics, is based on evolutionary history., The phylogenetic tree is also known as genealogical, tree or dendrogram., Phenetic taxonomy (classification) is based on, the overall similarity of organisms evaluated, without regard to phylogeny., Phenetic classification is based on observable, characteristics of existing organisms., Phenetic classification did not have a strong, impact on animal classification and scientific, interest in this aproach is on the decline., Table : Historical accounts, A.P. de Candolle (1813), E.H. Haeckel (1866), , –, –, , Copeland (1956), , –, , Whittaker (1969), , –, , John Ray (16271705), –, Carolus Linnaeus (1753) –, Adolf Meyer (1926), , –, , H.J. Lam (1948), , –, , Haeckel, , –, , Turill (1938), Julian Huxley (1940), , –, –, , Cuvier, , –, , Term Taxonomy, Three, Kingdom, Classification, Four, Kingdom, Classification, Five, Kingdom, Classification, Termed species, Binomial System of, Classification, Used taxon term w.r.t., animal kingdom, Used term taxon in, plant kingdom, Concept, of, phylogeny, Alpha taxonomy, Termed, New, systematics, Coined term phylum
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 6, , ŕďőĽę– ĐĽŐńŐĹť–, System of classification, , Two Kingdom, , Plant Kingdom, Animal Kingdom, , *, , *(Not approved as fungi and, organisms like Euglena,, Chlamydomonas etc. were, not justified in these two, kingdoms)., Monera, (all prokaryotic, organism), Archaebacteria, , Eubacteria, , Three Kingdom, [Proposed by, Haeckel, (1866)], , Five Kingdom, [Proposed by, R.H. Whittaker, (1969)], Used three criteria, Protista, – Complexity of cell structure, (for unicellular organisms), – Complexity of body structure, Monera (all plants), – Mode of nutrition, Plant (all plants), Divided into, Animal (all animals), , Four Kingdom, [Proposed by, Copeland, (1956)], , Plant, Animal, Protista, (for unicellular, organisms), Protista, (unicellular, eukaryotes), Photosynthetic, , (eukaryotic,, heterotrophic, organisms), , Consumer, Protozoa, , l, , l, , l, , l, l, l, l, , Organisms are classified according to two, three,, four, five and six kingdom system (Ref er, flowchart)., The major criteria used for delimitation of, kingdoms are modes of nutrition, presence or, absence of locomotion, complexity of, organisation, and cell structure., Viruses do not fit neatly into any classification of, living organisms because they have a very simple, noncellular structure and cannot exist independently, of other organisms., Herbarium is a collection of plant parts that usually, have been dried, pressed, preserved on sheets., Largest herbarium of the world is at Kew., Botanical gardens are the collections of living, plants maintained for reference., The largest botanical garden is the Main, , l, l, l, l, l, l, , l, l, , Plantae (nonmobile and, photosynthetic organisms), Algae, Bryophyte, Pteridophyte, Gymnosperms, Angiosperms, , Animalia, (Metazoa), , Botanical Garden, Moscow covering an area of, 900 acres., The Royal Botanical Garden, Kew England covers, an area of 300 acres., Indian Botanical garden, Sibpur, Kolkata, is the, largest botanical garden in India., The collection of plants and animals are preserved, and kept in museums for study and reference., Zoological parks are zoos which help to study, wild animals and their food habits., Camerarius was the person who first recognised, sexuality in plants., If the generic and specific names are same it is, called tautonym. But tautonyms have been rejected, by modern scientists., Angiosperms are the most advanced type of, plants., Angiosperms contain seeds enclosed in fruits.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 7, , ♠ĽŕśřĚř–, , Chapter 2, , Viruses, The term ‘Virus’ has been derived from Latin,, which means poison or venom or viscous fluid., Viruses are defined as infectious nucleoproteins., Virus are obligate intracellular parasite which can, reproduce only by invading and taking over other, cells as they lack the cellular machinery for self, reproduction., , l, , l, l, , Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, , l, , A complete virus particle is called virion whose, main function is to deliver its DNA or RNA genome, into the host cell. So that genome can expressed, (transcribed and translated) by the host cells., , Characteristic features, l, , These are submicroscopic organisms generally less, than 200 mm., , Important inventions, Viruses were discovered after Chamberland developed bacterial filters (1884)., Meyer (1886) describe tobacco mosaic disease but he couldn’t isolate the causal organism. Further, he said, that the disease is transmissible and infectious., Russian botanist D. Ivanowski (1892), discovered the causal organisms of tobacco mosaic disease and this, causal organisms could pass through the filters which retained bacteria., Beijerinck (1898) confirmed the earliest studies and named these organisms as “Contagium vivum fluidum”,, living infectious fluid., F.W.T’wort. (1915) and F.H.d’Herelle (1917) discovered certain viruses which infect bacteria or bacteria, eaters i.e., bacteriophages or phages., Stanley (1935) crystallized tobacco mosaic virus and said that these crystals retain their infectivity for a long, time if kept in bottles., Bawden and Pirie (1936) first of all studied the chemical nature of viruses and said that these are nucleoproteins., Edward Jenner (1796) discovered vaccination against small pox, Louis Pasteur (1880) discovered vaccination against rabies, Loeffler and Frosch (1898) discovered first animal pathogenic virus (Foot and mouth virus of cattle)., S. Luria, M. Delbruck and Lwoff (1942 48) discovered mechanism of replication in bacteriophages., A. Harshey and M. Chase (1952) said that nucleic acids are infective and proteins are noninfective parts, of a bacteriophages., T. O. Diener (1971) discovered some new infectious agents, which are still smaller than viruses., Stanley B. Prusiner discovered certain infectious agents or slow viruses which contain only proteins., Prusiner got Nobel prize for this work in 1997., Alliac Issacs and Lindeman (1957) gave the term interferons to the chemical substances responsible for, viral interference., Mycophages, viruses infecting fungi, were discovered by Sinden (1957) in Agaricus bisporus. These are, having double stranded RNA and are spherical or polygonal in shape., A. Salk (1957) invented vaccination against Polio, Lu Montagnier et. al. (1893); R. Gallo et. al. (1984) discovered AIDS virus for HIV., Safferman and Morris (1963) discovered cyanophages (viruses infecting cyanobacteria like Lynggya).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 8, , l, , l, l, l, l, , l, , l, , l, , l, , l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Shape of virus is variable, eg., brick shaped, (influenza virus), rod shaped (TMV), tadpole like, (bacteriophages)., They are obligate parasites i.e., can live inside, living host only., They have either RNA or DNA., They can pass through bacterial filters., They have characteristic mode of multiplication,, i.e., once a virus enters into the host cell, it takes, control of whole biochemical machinery of host, cell and orders the metabolic machinery to, synthesize their own (viral) components., Non living characters of viruses are –, –, No protoplasm, –, No enzyme system, –, No respiration, –, They can be crystallized, –, Do not grow in culture medium., Living characters of viruses are –, –, They contain nucleic acid as a result of which, they are capable of synthesizing proteins., –, They can multiply inside living host cell., –, They causes diseases., On the basis of above characters it can be said that, viruses form a transitional group between living, and nonliving., Viruses are divided into two main groups on the, basis of the type of nucleic acid present in them., –, Deoxyvira (having DNA)., –, Ribovira (having RNA)., Deoxyvira are further divided into three classes –, deoxyhelica (helical), deoxycubica (cuboidal) and, deoxybinala (binal)., Ribovira is divided into two classes ribohelica, (helical) and ribocubica (cuboidal)., F. O. Holmes (1948) divided order Virales into, three suborders –, –, Phytophaginae – Viruses, infecting plants, –, Zoophaginae – Viruses, infecting animals, –, Phaginae, – Viruses infecting bacteria, Structurally viruses are made up of envelope, capsid,, nucleoid and occasionally one or two enzymes., Some viruses possesses an outer thin loose covering, called envelope. It is composed of proteins (from, virus), lipids and carbohydrates (both from host)., It has subunits called peplomeres., The viruses, which do not possess envelope, are, called naked., , l, , l, , l, l, , l, , l, l, , l, , l, l, , l, , Capsid is the protein coat that surrounds the central, protein of nucleoid and enzymes (if present). The, capsid consists of a specific number and, arrangement of small subunits called capsomeres., The nucleic acid present in the virus is called, nucleoid. It is the infective part of virus which, utilizes the metabolic machinery of the host cell, for synthesis and assembly of viral components., Nucleoid represents the viral chromosomes., The genetic material of viruses are of 4 types –, double stranded DNA (ds DNA), single stranded, DNA (ssDNA), double stranded RNA (dsRNA), and single stranded RNA (ssRNA)., Double stranded or dsDNA are – adenovirus,, herpes simplex virus, pox virus, cauliflower, mosaic, coliphage lambda T4 (linear), hepatitis B,, simian virus SV – 40, polyoma (circular or cyclic)., Single stranded or ssDNA are – coliphage MS 2,, coliphage fd (linear), coliphage f × 174 (cyclic)., Single stranded or ssRNA are poliomyelitis virus,, foot and mouth disease virus, influenza virus, rous, sarcoma virus, retroviruses, turnip yellow mosaic, viruses, tobacco necrosis virus, TMV, potato, mosaic virus, bean mosaic virus (all linear)., ssRNA is of two types – negative stranded (RNA, – RNA viruses) and positive stranded (RNA –, DNA viruses or retroviruses)., Double stranded or dsRNA are reovirus, wound, tumour virus (all linear)., Only few viruses contain certain enzymes. For eg.,, lysozyme in bacteriophages, reverse transcriptase, in retroviruses., Symmetry of viruses may be –, –, Helical symmetry : Capsomeres, are, arranged in helical, manner in the capsid,, e.g., TMV., –, Cubical symmetry : Capsomeres, are, arranged on the surface, to form a 20 side cube,, e.g., turnip mosaic virus., –, Biosymmetrical or : Bacteriophages, mixed symmetry, , TMV (Tobacco Mosaic Virus), l, , TMV is the most thoroughly studied virus and was, discovered by the Russian worker D. Ivanowski, (1892).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♠ĽŕśřĚř–, l, l, l, l, , It is a rod shaped virus measuring 300 × 18 nm and, have helical symmetry., Have single stranded DNA which is 330 nm in, length and having 7300 nucleotides., Number of capsomeres in capsid is 2130., 5% RNA and 95% protein is present in TMV., , Bacteriophages, l, , l, l, , l, l, l, l, , l, , l, , Viruses infecting bacteria are known as, bacteriophages or phages. Sea water can hold 100, million bacteriophages per µl., Bacteriophages may be virulent or avirulent., Prophages or nonvirulent phages or non, infective phages are the phages which do not cause, lysis of bacteria soon after their formation inside., Such bacterial cells which are having prophages, inside them are called lysogenic bacteria., Virulent phages or infective phages are the phages, which cause lysis of bacterial cell at once., Most studied series of bacteriophages is Tseries, (T2, T4, T6 etc.)., Teven phages are characterized by angular head, and contractile tail., Bacteriophages have tadpole like structure, i.e., with, head and tail. Inside the head is present nucleic, acid, generally DNA., Head is prism like hexagonal having length 950Å, and breadth 650Å, tail is also 950Å in length, joined, to head by neck and collar, tail is having hollow, core of 80Å and is surrounded by tail sheath., At the end of tail, end plate is present to which 6, tail fibres are attached and each is 1500Å in length., , Lytic cycle (T4 bacteriophage), l, The multiplication process of virulent phage is, called lytic cycle., l, The main steps include adsorption, penetration,, formation of new phages and lysis., l, Bacteriophage attaches to the surface of, bacterium by its tail fibres., l, Lysozymes creates a hole in the host cell wall., l, The tail sheath contracts and ejects the viral, chromosome/DNA into the bacterium., l, Viral DNA controls the metabolic machinery of, the host cell. It produces nucleases., l, Nucleases degrade DNA and mRNAs of the host., l, Viral DNA is not affected as its cytosine bases are, methylated., l, A number of copies of viral DNA are produced, , l, l, , 9, , followed by synthesis of capsid protein,, polyamines and lysozymes., The components assemble and form phage particles, or viruses., The host cell ruptures to release viruses (lysis)., , Lysogenic cycle (l phage), The multiplication process of temperate phage is, called lysogenic cycle., l, The phenomenon of existence of nonvirulent, prophage in the host cell is called lysogeny., l, The host cell in which lysogeny occurs is called, lysogenic cell., l, Lysogen is a strain of bacteria carrying prophage., l, Lysogenic cycle is shown by 1 (lambda) phage, which also infects E.coli bacterium., l, Lytic bacteriophage multiply in host bacterium, which then undergoes complete lysis (degeneration), to release the resulting daughter phages., l, The phage attaches to the surface of bacteria by, means of tail, which produces a hole in host cell, wall and injects the phage DNA., l, Phage DNA produces a repressor, (C1) becomes, nonvirulent or temperate and gets integrated to, bacterial chromosome at a specific site by means, of enzyme integrase., l, The viral genome is now called prophage/provirus., l, It multiplies alongwith bacterial genome and is, passed on to the progeny., l, Occassionally the synthesis of repressor is stopped, due to ultra violet radiations or chemical factors., l, The temperate/nonvirulent phage is now changed, to lytic/virulent phage., l, The single strand DNA of f × 174 or coliphage fd, is known as plus strand. It forms its complementary, or negative strand. The double strand or replicative, DNA takes over the metabolic machinery of host, to synthesize plus strands DNAs and protein for, assembly of new phages., l, , Pinocytic reproduction, l, The whole virus enters the host cell except the, envelope. It is quite common in RNA viruses, which are of two types as RNARNA virus and, RNADNA virus., l, In RNARNA viruses DNA has no role in their, multiplication. After entering the host cell the, viruses produce enzyme replicase which helps, in producing more genetic RNA over the template
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 10, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , of parent RNA genome. The latter also produces, mRNAs for synthesis of viral proteins., RNADNA viruses are also called retroviruses, (Temin, 1970), e.g., Tumor/Cancer viruses, HIV., The virus es p os sess enzyme rev e rs e, transcriptase (Temin and Baltimore, 1972; in, Rous Sarcoma Virus or RSV of Mouse). The, enzyme builds DNA over RNA genome. The, phenomenon is called reverse transcription or, teminism., The copy DNA (cDNA) builds its complementary, strand. The double strand copy DNA attaches to, host DNA/chromosome and is now called, provirus., Application of bacteriophages are –, –, Studying viral infection mechanism., –, Control of certain bacterial diseases., –, Purity of Holy Ganges is due to presence of, bacteriophages., Viroids are subviral infectious agents, which, contains only very low molecular weight RNA and, not protein coat. Viroids cause potato spindle tuber, disease (PSTV), citrus exocortis etc. The only, human disease known to be caused by a viroids is, hepatitis D., Interferons are protein molecules which prevent, viral multiplication. These are produced by cells in, mammals, rodents, birds, etc. and provide resistance, against viruses., , l, , l, , Diseases caused by viruses, l, l, , Virus causes diseases in plants, animals and human, brings., Plant diseases caused by viruses are –, –, Tobacco mosaic disease, –, Leaf curl of papaya, –, Yellow vein mosaic of bhindi, –, Potato leaf roll, –, Vein bandings mosaic disease of potato, –, Grassy shoot of sugar cane, , l, , –, Bunchy top of banana, –, Tungro disease of rice, –, Tomato leaf curl, Human diseases caused by viruses are –, Chicken pox, :, Varicella virus, Small pox, :, Variola virus, Measles, :, Rubeola virus, Rabies, :, ssRNA (Rabies virus , Lassa virus), AIDS, :, ARV (Aids associated, retrovirus), Yellow fever, :, Transmitted by Aedes, aegypti mosquito, Dengue fever, :, Transmitted by Aedes, aegypti mosquito, Polio, :, Transmitted through food,, water, contact, HepatitisB, :, Transmitted through contact, and body fluid., Transmission of viruses occurs by –, –, Polluted air, water and food stuffs help the, dissemination of viruses in man and animals., –, Fly and mosquitoes usually act as carriers., –, Such virus transmitting agents are called vectors., –, Most of the virus diseases of plants are, transmitted through insects., –, Sap sucking insects like aphids and white flys, are the important ones among such vectors., –, Virus diseases are also transmitted through, stem cuttings, seeds, tubers, agricultural, implements etc., Disease can be controlled by –, –, Removal of diseased plants and plants parts., –, Using disinfested seed., –, Testing the germplasm and selecting virus free, seed., –, Destruction of alternative hosts., –, Destruction of insect vectors., –, Practising crop rotation., –, Growing disease resistant varieties.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 11, , █ĽňĹęŐŇ– ▐ŐňĚŕď–, , Chapter 3, , Kingdom Monera, l, l, l, l, l, l, l, l, l, , Monera are the group of all prokaryotes., They are basically unicellular, may be mycelial,, colonial and filamentous., Cell wall is made up of peptidoglycan,, polysaccharides and cellulose., They do not contain any organised nucleus with, distinct membrane., DNA is naked, i.e., not associated with histone, proteins. It is called nucleoid., All the membrane bound cell organelles are absentlike, mitochondria, lysosomes, golgi bodies, plastids etc., In photoautotrophic forms thylakoids are present , without chloroplasts., Spindle apparatus do not develop at the time of cell, division., Single stranded flagella, composed of flagellin, is, present., , l, l, l, , l, l, l, , Ribosomes are 70S type (subunit 30S and 50S)., Reproduction is by binary fission or budding., They have a various modes of nutrition like, saprobic,, parasitic,, chemoautotrophic,, photoautotrophic, symbiotic., Some are capable of nitrogen fixation., Monera occur in all environment, eg archaebacteria, live in extreme climates., The kingdom includes all prokaryotes like bacteria,, actinomycetes, mycoplasma and cyanobacteria., , BACTERIA, l, l, , Bacteria are the smallest of free living organism,, mostly unicellular., Bacteria possess various forms and shapes, and are, of 4 different types – coccus, bacillus, vibrio,, and spirullum., , Bacteria based on shape, , Coccus, (round), , Bacillus, (rod shaped), , Diplobacillus (In groups of two), , Vibrio, (comma shaped,, e.g., Vibrio cholerae), , Palisade bacillus (Like a stack), , Spirullum, (spiral like corkscrew,, e.g., Spirochaete), , Streptobacillus (In chains), , Tetracoccus, Streptococcus Staphylococcus, Micro, Diplo, Sarcinae, (Occurs singly) (Groups of two) (In groups of four) (Forms a chain) (Bunch of grapes) (Cubes of 8, 64 or more), Bacteria based on flagellation, Atrichous, flagella absent, e.g., Lactobacillus, , Monotrichous, single flagella, at one end, e.g.,, Vibrio cholerae, , Lophotrichous, groups of flagella, at one end, e.g.,, Spirullum, , Amphitrichous, single flagella, at each end, e.g.,, Nitrosomonas, , Flow chart : Classification of bacteria, , Peritrichous, flagella present all, over the body,, e.g., E. coli
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 12, , l, , l, , l, l, l, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Bacteria possess a distinct cell wall, with different, wall layers like capsule or slime layer, plasma, membranes, flagella and pilli., Slime layer or capsule is made up of, polysaccharides and amino acids and acts as, osmotic barrier., Cell wall is made up of polysaccharides, proteins, and lipids and peptidoglycan or murein., Plasma membrane is tripartite in nature., Mesosomes are simple infolding of plasma, membrane containing respiratory enzymes, like, oxidases and dehydrogenase., Flagella is made up of flagellin., Pili are small hair like outgrowth present on, bacterial cell surface made up of pilin protein., Pilin helps in formation of conjugation tube and, agglutination., Based on the nature of staining, bacteria may be, Gram + ve (retains the blue stain) or Gram –ve, (does not retain the stain)., Gram staining, Heat fixed smear of bacteria, Crystal violet, Rinse with water, , Table : Difference in the cell walls of gram +ve &, gram –ve bacteria, Gram +ve bacteria, 1. Cell wall more thick,, thickness varies from, 2530 nm., 2. Cell wall is a, homogenous layer., 3. High, content of, peptidoglycan (2080%, of the dry weight of the, cell)., 4. Teichoic acids may be, present., 5. Very little lipid content, (02%)., 6. Only a few aminoacids, are associated with the, muramic acid complex., 7. Lipopolysa ccha ride, layer (LPS) absent., 8. Periplasmic space is, absent., l, , Add dilute iodine solution, All bacterial cell appears deep blue, Treat with 95% alcohol, Cells retain purple, colour, Gram +ve bacteria, l, , l, , l, , l, , Destained and appear, red in colour, Gram –ve bacteria, , Inner to the wall layers, there is present matrix or, protoplasm which includes nucleoid, plasma,, episomes, ribosomes, and granules., In the centre of the bacterial cell, there is present, nuclear material (DNA) without any nuclear, membrane (naked). DNA in bacteria is double, helical and circular., This incipient nucleus or primitive nucleus is named, as nucleoid or genophore (sometimes called single, naked chromosome)., Besides this nuclear DNA, there is some, extranuclear or extrachromosomal DNA, which is, known as plasmid., , l, l, l, , l, l, l, , l, , l, l, , Gram –ve bacteria, Cell wall thin.Thickness, varies 1015 nm., Three layered., Less, content, of, peptidoglycan (1020% of, the dry weight of the cell)., Teichoic acids absent., High lipid content (10, 20%)., Large, variety, of, aminoacids are associated., Present., Present., , The plasmid are small, circular, double, stranded DNA molecules that are separate from, ma in b acteria l chromosome and rep lica te, independently., The term plasmid was given by Lederberg (1952)., Plasmids have an independent existence., Plasmids carry genes for fertility, antibiotic, resistance (Rfactor) and bacterium (Colicin), production (colicinogenic factor)., Ffactor or fertility factor is responsible for, transfer of genetic material., Rfactor or resistance factor provides resistance, against drugs., Colicinogenic factor produces ‘colicines’ which, kill other bacteria (other than which produces these, colicines)., The term episome is applied to extranuclear genetic, material which may remain in integrated or free, state, e.g., Ffactor, temperate phage, etc., Ribosomes are evenly distributed in the matrix., Ribosomes are of 70S type (50S + 30S)., Ribosome are the seat of protein synthesis and are, made up of rRNA and protein.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, █ĽňĹęŐŇ– ▐ŐňĚŕď–, l, , l, , l, , l, , l, , l, , There are present different types of granules like, volutin granules, fatty acid granules (lipid granules),, glycogen and sulphur granules., According to the mode of respiration, bacteria, can be aerobic or anaerobic. Each of them is further, of two types, obligate and facultative., Obligate aerobes are bacteria which can respire, only aerobically. They generally get killed under, anaerobic mode of respiration, e.g., Bacillus subtilis., Facultative aerobes are bacteria which respire, anaerobically under normal conditions but can, respire aerobically when oxygen is available. Most, of the photosynthetic bacteria belong to this group., Obligate anaerobes are bacteria that respire only, anaerobically. They generally get killed under, aerobic condition, e.g., Clostridium botulinum., Facultative anaerobes are bacteria which generally, respire only aerobically but switch over to anaerobic, mode of respiration if oxygen becomes deficient., , l, , l, , l, , Nutrition, l, l, , l, , l, , l, , l, , Bacteria show both autotrophic and heterotrophic, nutrition., Autotrophic nutrition consists of manufacture of, organic materials from inorganic raw materials with, the help of energy obtained from outside sources., It is of two types – chemosynthesis and, photosynthesis., The bacteria possess photosynthetic pigments of, two, types,, bacteriochlorophyll, and, bacteriophaeophytin (chlorobium chlorophyll)., The two types of pigments respectively occur in, purple bacteria (e.g., Thiopedia rosea,, Rhodopseudomonas) in membranes of thylakoids., No oxygen is evolved in bacterial photosynthesis., Such type of photosynthesis is known as, anoxygenic photosynthesis., Water is not used as a source of reducing power., Instead, hydrogen is obtained either directly (some, purple bacteria) or from various types of inorganic, and organic compounds, e.g., H2S (green bacteria),, aliphatic compounds (purple nonsulphur bacteria)., Chemoautotrophic bacteria are bacteria which, are able to manufacture their organic food from, inorganic raw materials with the help of energy, derived from exergonic chemical reactions, involving oxidation of an inorganic substance, present in the external medium. They are of various, types., , l, , l, l, , l, , l, , l, , 13, , Nitrifying bacteria, Nitrosomonas and, Nitrosococcus obtain energy by oxidising ammonia, to nitrite., NH4+ + 2O2 ® NO2– + 2H2O + Energy, Nitrocystis and Nitrobacter oxidise nitrites to, nitrates., 2NO2– + O2 ® 2NO3– + Energy, Sulphur oxidising bacteria, Beggiatoa, a, colourless sulphur bacterium, oxidises hydrogen, sulphide to sulphur in order to obtain energy for, chemosynthesis., Beggiatoa, 2 H 2 S+ O 2 ¾¾¾¾¾, ® 2S+ 2 H 2 O+ Energy, Thiobacillus thioxidans, another sulphur bacterium,, oxidises sulphur to sulphate state., Beggiatoa, 2S+ 2 H 2 O + 3O 2 ¾¾¾¾, ¾, ® 2H2SO4 + Energy, Thioxidans, Iron bacteria, Ferrobacillus ferrooxidans obtains, energy by oxidising ferrous compounds to ferric, forms., 4FeCO3 + 6H2O + O2 ®, 4Fe(OH)3 + 4CO2 + Energy, Other chemosynthetic bacteria, bacterium, Methanomonas oxidises methane into CO2 and, H2O., CH2 + 2O2 ® CO2 + 2H2O + Energy, Heterotrophic bacteria may be saprophytic,, parasitic or, symbiotic., Saprophytic are living bacteria which obtain, their food from organic remains, e.g., corpses,, animal excreta, fallen leaves, vegetables, fruits,, meat, jams, jellies, bread and other products of, plant and animal origin., Symbiotic bacteria live in mutually beneficial, association with other organisms. Enteric bacterium, Escherichia coli, live as a symbiont in human intestine., Parasitic bacteria, live in contact with other living, beings for obtaining nourishment or special organic, compounds required for growth (growth factors)., Bacteria show four major phases of growth in a, fresh nutrient rich medium – (i) lag phase, (ii) log, phase (logarithmic or exponential phase),, (iii) stationary phase, and (iv) decline phase (death, phase). These phases constitute the standard, bacterial growth curve., , Reproduction, l, , Bacteria show 3 methods of reproduction –, vegetation reproduction, asexual reproduction,, sexual reproduction.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 14, , l, l, , l, l, , l, , l, , l, l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Vegetative reproduction includes budding and, binary fission., Binary fission takes place during favourable, conditions. The bacterial cell divides by a, constriction into 2 halves. The nuclear material also, divides into 2 equal halves., Asexual reproduction takes place by endospore, formation, conidia and zoospores., During unfavourable condition, highly resistant, single spore is formed inside the bacterial cell,, which is known as endospore. (Endo means inside, or within + spore)., Endospore is having a characteristic structure i.e.,, having outer thin exosporium followed by one or, many layered spore coat, followed by many, concentric layers of cortex, which is followed by, cell wall, cell membrane and matrix., Endospore is highly resistant to very high and, very low temperature, strong chemicals and, acids, etc. due to calcium, dipicolinic acid and, peptidoglycan in cortex. Dipicolinic acid (DPA), helps in stabilizing its proteins., DPA and Ca ions provide resistance to heat., When favourable conditions come, outer layers, rupture and active bacterial cell comes out. So this, is a method of perennation (i.e., to tide over, unfavourable condition) and some people say it, “reproduction without multiplication”., Sexual reproduction occurs in the form of genetic, recombination., There are there main methods of genetic, recombination – transformation, transduction,, conjugation., Transformation : Here genetic material of one, bacterial cell goes into another bacterial cell by, some unknown mechanism and it converts one type, of bacterium into another type (noncapsulated to, capsulated form)., This was first studied by Griffith (1928) in, Diplococcus pneumoniae and hence is known as, Griffith effect., Transduction : In this method, genetic material of, one bacterial cell goes to other bacterial cell by, agency of bacteriophages or phages (viruses,, infecting bacteria)., Transduction was first of all reported in Salmonella, typhineurium by Zinder and Lederberg (1952)., , l, l, , l, l, , l, , In abortive transduction the new gene does not, integrate with the recipient genome and is lost., Conjugation : Cell to cell union occurs between, two bacterial cells and genetic material (DNA) of, one bacterial cell goes to another cell lengthwise, through conjugation tube which is formed by sex, pili., Conjugation was first reported by Lederberg and, Tatum (1946) in E. coli bacteria., Conjugation occurs between donor cell and, recipient cell. Donor cell is having sex pili and F, factor whereas recipient cell is having both., In donor cell, Ffactor may unite with main genome, or nuclear DNA and this donor cell is called Hfr, donor cell (High Frequency donor cell) and here, transfer of DNA is rapid., , Importance of bacteria, Useful activities, l, Role of bacteria in agriculture in increasing soil, fertility, –, Some free living nitrogen fixing bacteria like, Azotobacter and Clostridium have the capacity, of fixing atmospheric nitrogen into, nitrogenous substances, hence increases soil, fertility., –, Similarly symbiotic bacteria Rhizobium also, fix atmospheric nitrogen., –, Nitrosomonas converts ammonia into nitrites,, which is further converted into nitrates by, Nitrobacter (nitrification)., l, In dairy industry, lactic acid bacteria (Bacterium, lacticiacidi and Bacterium acidilactici) convert, lactose of milk into lactic acid and hence milk turns, sour., l, In other industries, –, In vinegar industry, Acetobacter acetic, converts sugar solution into acetic acid., –, Butyl alcohol and acetone are produced by, activity of Clostridium acetobutyricum., –, Retting or separation of fibres from stalks,, e.g., in jute, sunhemp, Linum (flax), etc. is, done by water inhabiting bacteria Clostridium, butyricum., –, Flavouring of tobacco leaves is done by, Bacillus megatherium., –, Curing of leaves of tea is done by Mycococcus, condisans.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 16, , Ø, , Ø, Ø, , ŕďőĽę– ĐĽŐńŐĹť, , Some other types of bacteria, Spirochaetes are free inhabitants of mud and water and are chemoheterotrophic bacteria., Many diseases are caused by them as Treponema pallidum causes syphilis, Leptospira causes infectious, jaundice and Borrelia causes relapsing fever. Besides some spirochaetes are found in teeth., Rickettsiae are Gram negative obligate pleomorphic but walled intracellular parasites which are resident, of or are transmissible from arthropods. They are intermediate between true bacteria and viruses., Chlamydiae are Gram negative intracellular parasites of about 0.25 µm size, often grouped along rickettsiae, but differ from them in reproductive cycle that involves formation of initial or reticulate bodies (RB) and, elementary bodies inside host phagosome. Chlamydia trachomatis causes conjuctivitis, sexually transmitted, nongonococcal urethritis, epididymitis, cervicitis, proctitis and lymphogranuloma venereum. C. pneumoniae, causes pneumonia and bronchopneumonia., , ACTINOMYCETES, l, , l, l, l, l, , l, , l, l, , l, , Actinomycetes are mycelial (aseptate branched, filaments) bacteria which form radiating, colonies in culture. Because of this, actinomycetes, were formerly called ray fungi., Mycelial form is reduced in Mycobacterium and, Corynebacterium., Mycelia have a diameter of 1mm or less., Wall contains mycolic acid (fatty acid), lipid and wax., Different modes of reproduction are by conidia,, sporangiospores and arthrospores or oidia and, fragmentation., Most of the actinomycetes are saprotrophic and, constitute an important component of decomposers,, e.g., Actinomyces, Streptomyces., A few are pathogenic in plants, animals and humans,, e.g., Mycobacterium., In pathogenic actinomycetes or Mycobacterium a, derivative of mycolic acid called mycoside/cord, factor is involved in causing disease., A number of antibiotics are produced by, actinomycetes, especially the genus Streptomyces, (streptomycin, chloramphenicol, tetracyclines,, terramycin, erythromycin, viomycin, novobiocin,, nystatin)., The term antibiotic was given by Abraham, Selman Waksman (1888 1973) who also, extracted first antibiotic from Streptomyces, griseus and named it streptomycin. For this, Waksman was given Nobel Prize in 1952., , ARCHAEBACTERIA, l, , They are a group of most primitive prokaryotes, which are believed to have evolved immediately, after the evolution of the first life. They are also, called living fossils., , l, l, , l, l, , l, l, , l, , Archaebacteria are characterised by absence of, peptidoglycan in their wall., Instead the wall contains protein and non, cellulosic polysaccharides. It has pseudomurein, in some methanogens., The cell membranes are characterised by the, presence of a monolayer of branched chain lipids., Archaebacteria even now live under extremely, hostile conditions where very few other organisms, can dare subsist, e.g., salt pans, salt marshes, hot, sulphur springs., Their rRNA nucleotides are quite different from, those of other organisms., The archaebacteria are of two broad categories –, obligate anaerobes and facultative anaerobes or, aerobes., Archaebacteria are of three types – methanogens,, halophiles and thermoacidophiles., Archaebacteria are also known as living fossils, because they represented one of the earliest forms, of life which experimented on the absorption of, solar radiations for the first time, lived comfortably, under anaerobic conditions and developed, techniques to oxidise the chemicals present in the, substratum on the availability of oxygen., , Methanogens, l, l, , l, l, , These archaebacteria are strict anaerobes., Nutritionally they are “autotrophs” which obtain, both energy and carbon from decomposition, products., They occur in marshy areas where they convert, formic acid and carbon dioxide into methane., This capability is commercially exploited in the, production of methane and fuel gas inside gobar gas, plants. E.g., Methanobacterium, Methanococcus.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 17, , █ĽňĹęŐŇ– ▐ŐňĚŕď–, l, , Some of the methanogen archaebacteria live as, symbionts (e.g., Methanobacterium) inside rumen, cow, buffalo and helpful to the ruminants in, fermentation of cellulose., , Halophiles, l, , l, l, l, l, l, , l, , Halophiles are named so because they usually occur, in salt rich substrata (2.5 5.0 M) like salt pans,, salt beds, and salt marshes, e.g., Halobacterium,, Halococcus., They are aerobic chemoheterotrophs., Their cell membranes have red carotenoid pigment, for protection against harmful solar radiations., Under anaerobic conditions, halophiles cannot use, external materials., At this time they subsist on ATP, synthesized by, membrane pigmented system from solar radiations., Halophiles growing in salt pans and salts beds gives, offensive smell and undesirable pigmentation to, the salt., Halophiles are able to live under high salt, conditions due to the following reasons –, –, Presence of special lipids in the cell, membranes., –, Occurrence of mucilage covering., –, Absence of sap vacuoles and hence, plasmolysis., –, High internal salt content., , Thermoacidophiles, l, , l, , l, , l, , l, l, , These archaebacteria have dual ability to tolerate, high temperature as well as high acidity due to, two reasons branched chain lipids in the cell, membranes and presence of special resistant, enzymes capable of operating under acidic, conditions., They often live in hot sulphur springs where the, temperature may be as high as 80°C and pH as low, as 2, e.g., Thermoplasma, Thermoproteus., Basically these archaebacteria are chemosynthetic, i.e., they obtain energy for synthesis of food from, oxidising sulphur., Under aerobic conditions they usually oxidise, sulphur to sulphuric acid., 2S + 2H2O + 3O2 ® 2H2SO4., If the conditions are anaerobic, the, thermoacidophiles may reduce sulphur to H2S., Bicarbonates are also precipitated into the carbonate, form by their activity., , MYCOPLASMA (PPLO), l, l, , l, , l, l, , l, , l, l, , l, , l, , l, l, l, , l, l, , l, l, , Mycoplasmas or mollicutes are the simplest and, the smallest of the free living prokaryotes., They were discovered in pleural fluid of cattle,, suffering from pleuropneumonia by Nocard and, Roux, (1898)., The organisms are often called MLOs, (Mycoplasma like Organisms) or PPLOs, (Pleuropneumonia like Organisms)., The size ranges from 0.1 0.15 mm., Plasma membrane forms the outer boundary of the, cell. A substantial amount of polysaccharides, having even acetyl glucosamine are associated with, cell membrane which is rich in cholesterol., A cell wall is absent. Due to the absence of cell, wall the organisms can change their shape and are, pleomorphic – cocoid, cocobacillus, helical, fine, unbranched or branched., Like other prokaryotes, mycoplasmas possess one, envelope system., They lack organised nucleus, endoplasmic, reticulum, plastids, mitochondria, golgi bodies,, lysosomes, centrioles, flagella etc., The genetic material is represented by a single DNA, duplex which is naked because of absence of, histone association., The DNA duplex is not compacted as in other, prokaryotes but instead lies coiled throughout, the cytoplasm., Ribosomes are 70s. Granules of various types occurs, here and there in the cytoplasm, mesosomes absent., Enzymes lie both freely in the cytoplasm as well, as associated with the plasma membrane., DNA possesses a replicating disc at one end to, assist in replication and separation of the genetic, material., Some of them live as saprophytes but majority, parasites plants and animals., The parasitic habit is due to the inability of most, mycoplasmas to synthesize the required growth, factors, e.g., Mycoplasma gallisepticum., Electron transport system is rudimentary or absent., Reproduction occurs by fission or first forming, a branching filament with numerous nuclear, bodies followed by constriction in between the, nuclear bodies and separation of cells as new, individuals.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 18, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , They mostly produce pleuropneumonia in domestic, animals, atypical pneumonia and mycoplasmal, urethritis in humans, little leaf disease of brinjal, and witches broom in plants., Mycoplasmas are not affected by penicillin, (inhibitor of wall formation) but are inhibited by, tetracyclines., , CYANOBACTERIA, (BLUE GREEN ALGAE), General characters, l, l, l, l, l, l, , l, l, , l, , l, , l, l, , l, , Cyanobacteria are gram –ve prokaryotes which, perform oxygenic photosynthesis like plants., They were the first organism to make the, atmosphere aerobic., The blue green algae live virtually in all, environments that contain water., The organisms range from tropics to plains and, they occur in soil, fresh water and ocean., In lakes and in the ocean they form part of planktons., Some cyanobacteria live in the icy water of glaciers, others in hot springs where temperatures reach 85°C, or more (due to homopolar bonds)., Some bluegreen algae live as symbionts with other, organisms, e.g., lichens., Cyanobacteria can be unicellular (e.g., Spirulina),, colonial (e.g., Nostoc) or filamentous (e.g.,, Oscillatoria). Filaments contain one or more, trichomes inside a mucilage sheath., Trichomes may be homocystous (without, heterocysts, e.g., Oscillatoria which shows apical, oscillations) or heterocystous (with heterocysts,, e.g., Nostoc, Anabaena)., Nitrogen fixing Nostoc and Anabaena live freely, as well as symbionts (in Azolla, Anthoceros, Cycas, roots, Gunnera stems amd nodules of Trifolium, alexandrintum)., The cell wall possesses an outer sheath (outside), which is jelly like, slimy and mucilaginous., The cell contents are divided into two regions –, outer chromatoplasm having photosynthetic, pigments in free thylakoids and inner colourless, centroplasm., The cell wall is two layered whose inner wall is, made up of peptidoglycan or mucopeptides built, up from amino sugars (eg., glucosamine) and amino, acids (eg., muramic, diaminopimelic)., , l, l, , l, l, l, , l, l, l, , l, , l, , l, , l, , l, l, , In the cytoplasm photosynthetic lamellae are, present., These lamellae or thylakoids contain dominating, pigments phycocyanin allophycocyanin and, phycoerythrin (phycobilins) in addition to, chlorophyll a., Bacteria and blue green algae lack mitochondria,, true vacuoles and endoplasmic reticulum., Sterols are absent in bacteria as well as, cyanobacteria., True nucleus is absent. True fibrils of DNA are, either distributed throughout the cell or concentrated, in the central part. Its chromosome resembles, bacterial chromosomes., Gas vacuoles are often present to regulate the, buoyancy in water., The colour ranges from green to deep purple often, blue green., Thes e colours are produced by different, proportions of several pigments like chlorophyll, a, carotene, xanthophyll, blue phycocyanin and, red phycoerythrin., Thylakoid membranes contain chlorophyll a,, carotenes and xanthophylls. Attached to thylakoids, are minute structure called phycobilisomes. They, have three types of water soluble but protein bound, accessory pigments – phycocyanin, allophycocyanin, (both blue) and phycoerythrin (red)., Many forms show Gaidukov phenomenon or, chromatic adaptation where colour changes, according to wavelength of light received by the, cyanobacteria. Trichodesmium erythaeum is, reddish coloured cyanobacterium which occurs in, such abundance that a sea is named after its colour, – red sea., Nucleoid is in contact with a group of coiled, membranes called lamellasome. Lamellasome, develops from plasmalemma. Plasmids or additional, small DNA rings may occur. 70 S ribosomes are, abundant., Cell inclusions are agranules (cyanophycean starch, similar to glycogen), bgranules (lipid droplets),, volutin granules and polyhedral bodies., The reserve food is in the form of cyanophycean, (myxophycean) starch., Flagella are absent in vegetative as well as, reproductive phase.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, █ĽňĹęŐŇ– ▐ŐňĚŕď–, l, , l, l, , l, l, , l, l, l, l, l, l, l, , l, , Well marked reproductive organs, sexual, reproduction and motile reproductive bodies are, absent in cyanobacteria., Reproduction is very simple and takes place by, vegetative means only., No trace of sexuality has ever been recorded but, gene recombination can occur through, conjugation, transformation and transduction., The vegetative reproduction occurs by mere cell, division., They reproduce asexually by binary fission (in, unicellular forms) and fragmentation (by breaking, up and regrowth of filaments)., Heterocysts formation is characterized by the, presence of thick walls and yellowish contents., Each heterocyst is made up of two walls an inner, thin layer and outer thick gelatinous layer., Heterocyst develops from recently divided cells, it, may be single or paired., On germination, it gives rise to a new filaments., In many filamentous forms asexual reproduction, occurs by hormogonia formation., They are identified by presence of biconcave discs, or separation discs between two adjacent cells., The filaments gets broken from such places into, many hormogonia and each of them forms a new, filaments, eg., Oscillatoria., Spore formation also occurs (exospores,, endospores, akinetes etc)., , Nitrogen fixation in cyanobacteria, l, , l, , l, , l, , Like many bacteria, several forms of bluegreen, algae have the capacity to fix atmospheric nitrogen, into nitrogenous compounds., This capacity is restricted to filamentous, heterocystous forms like Nostoc, Anabaena,, Aulosira etc., Under anaerobic conditions, some non, heterocystous forms can also fix atmospheric, nitrogen (Gloeocapsa, Oscillatoria)., This additional capacity of N2 fixation alongwith, CO2 fixation makes them truely autotrophic plants., , l, , l, , 19, , In this sense, they are considered to be largely, responsible for the maintenance of soil fertility in, tropical and temperate regions., Some species of blue green algae have a great, contribution to increase the fertility of rice fields, in tropical countries like India (e.g., Anabaena,, Tolypothrix, Aulosira)., , Economic importance of cyanobacteria, Useful aspects, l, Some fifty species of cyanobacteria are capable of, fixing atmospheric nitrogen in soil, e.g., Anabaena,, Nostoc., l, Spirulina is being used as a source of protein rich, supplement to diet of human., l, Bolls of Nostoc are used as food by Chinese and, South Americans. Food is called yoyucho., l, Cyanobacteria like Nostoc, Scytonema are used for, reclamation of usar (sterile, alkaline) soil., l, In Sambhar lake of Rajasthan, Anabaena and, Spirulina is produced in large number. Local people, use it as green manure., l, Some species of Anabaena, Tolypothrix help in, conservation of soil, thus checking soil erosion., l, Few cyanobacteria located inside lichens help in, plant succession due to their growth on barren land., l, Oscillatoria is used as pollution indicator., Harmful aspects, l, Forms like Anabaena not only spoil the taste of, drinking water but also produce toxic effect., l, Some cyanobacteria appear on buildings during, rainy season and cause damage to bricks etc., l, Skin infections may be caused by cyanobacteria, Lyngbya., l, Toxin secreting cyanobacteria are mainly, responsible for water blooms. These on death emit, foul smell, water gets contaminated with, chemoheterotrophic bacteria and unfit for normal, use., l, Some cyanobacteria like Rivularia release toxins, which is harmful for aquatic fauna.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, █ĽňĹęŐŇ– ▓ŕŐŚĽřŚď–, l, l, , l, l, , l, l, l, , l, l, , l, l, l, , l, , l, l, l, , l, , l, l, , Pennate types are bilaterally symmetrical and, centric types are radially symmetrical., Diatoms have cell walls containing silica,, constructed in two overlapping halves, which fit, together like two parts of a soap box (pennate types), or pair of petridishes (centric types)., The outer wall is called epitheca and inner wall, is a called hypotheca., They are present in both fresh and salt water and, comprise an important food for the aquatic animals., However, out of 5,500 species mostly are marine., They lack flagella and float mainly due to light, storage lipids present in them., Due to their silica impregnations, the walls of, diatoms are indestructible., As a result diatomaceous earth formation has, occurred due to remains of cell walls of diatoms in, the form of fossils., Silica wall of diatoms is designed with fine ridges,, lines, pores etc., These ornamentations are either radially, symmetrical or bilaterally symmetrical on either, side of the long axis of the cell., Food reserve is oil and chrysolaminarin or, leucosin (b 1 3 glucan), Multiplication is through binary fission., Binary fission reduces the size of most daughters, due to relation of one valve of the parents. This is, corrected through the development of, rejuvenescent cells or auxospores. Eg , Coscinodiscus, Stephanodiscus, Cymbella etc., Diatoms may exhibit slow gliding movements, produced by streaming of cytoplasm through, grooves on the surface of cell wall., Due to various designs over the cell wall, they have, been regarded as jewels of the plant kingdom., The oils extracted from some fishes and whales are, actually the ones produced by diatoms., Diatomite deposits are often accompanied by, petroleum fields. Much of the petroleum of today is, probably due to decayed bodies of the past diatoms., Diatomite is porous and chemically inert. It is, therefore, used in filtration of sugars, alcohols and, antibiotics., Diatomite is employed as a cleaning agent in tooth, pastes and metal polishes., Diatomite is added to paints for enhancing night, visibility., , l, l, , l, , 21, , Diatomite is employed as insulation material in, refrigeraters, boilers and furnaces., Diatomaceous earth is added to make sound proof, rooms. It is a good industrial catalyst and a source, of water glass or sodium silicate., Diatomite was at one time employed in handling, and storage of dynamite and strong acids., , Dinoflagellates, l, They comprise the phylum pyrrophyta of algae,, golden brown photosynthetic protists., l, They are single celled, most of them are surrounded, by a shell made up of thick interlocking plates, covered with cellulose cell wall., l, They are motile with two flagella (hence, dinoflagellates) one projecting from one end and, the other running in a transverse groove., l, Like diatoms they have fucoxanthin in addition to, chlorophyll., l, They are autotrophic and photosynthetic (e.g., Ceratium). Blastodium is a colourless parasite on, animals., l, The food reserves is in the form of oils and, polysaccharides., l, Most of the dinoflagellates are marine and important, photosynthesizer in the ocean., l, Occasionally members like Gonyaulax accumulate, in large numbers in some parts of sea, colouring, the water red and are responsible for red tide., l, Gonyaulax causes ‘red tides’ because it shows, bioluminescence or phosphorescence and make, the sea look red., l, Some species of dinoflagellates are poisonous to, vertebrates and when these accumulate, large number, of fish in that region of ocean may be killed., l, A noncontractile vacuole or pusule is present., l, Due to presence of two flagella at right angles to, each other, the dinoflagellates show peculiar, spinning movement. Hence, they are called, whorling whips., l, Nucleus is mesokaryon with condensed, chromosomes even in interphase. Histone is absent., Division occurs through dinomitosis in which the, nuclear envelope persists., l, Microtubular spindle is not formed. Chromosomes, are acentric and move while attached to inner, membrane of nuclear envelope., l, Dinoflagellates may have eye spots, trichocyst (e.g.,, Peridinium) and cnidoblasts (e.g., Nematodinium).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 22, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Some forms show bioluminescence or, phosphorescence, and are called fire algae e.g.,, Noctiluca, Gonyaulax., Method of reproduction is only asexual. Sexual, reproduction is usually absent (exception–, Ceratium)., Some species of dinoflagellates are taken as food, by mussels. These mussels remain unharmed by, dinoflagellates but if man eats these infected, mussels, he may fall ill., , Euglenoids, l, Euglenophyceae includes flagellate protists of fresh, water and damp soils., l, Presence of anterior invagination like some ciliates, has given the name plantanimals., l, Euglenoids are more advanced than bluegreen, algae from evolutionary point of view, for they, have a definite easily stained nucleus and the, chlorophyll is not scattered in granules but is, localized in chloroplasts as in higher plants. The, nuclear envelope persists during division., l, They are free living, found in fresh water ponds, and ditches or in the damp soil., l, Euglenoids are characterised by absence of cell, wall, but they do contain flexible pellicle made, up of protein., l, All the euglenoids have one or two flagella (tinsel, and tactellum) by means of which they can swim, easily., l, Euglena is more readily available protist for, laboratory studies., l, Euglena bears a flagellum inserted at the anterior, end in a cavity., l, They bear a red pigmented eye spot and a gullet, near the base of the flagellum. The pigment in eye, spot is astaxanthin., l, A swelling called paraflagellar body is found in, the region of union of flagellar roots., l, Photosynthetic forms bears many, radiating, chloroplasts of various shapes., l, The chloroplasts contain pigments like, chlorophyll a, chlorophyll b, xanthophyll., l, Nucleus with one or more prominent nucleoli occurs., l, Pyrenoids may or may not be present., l, Some euglenoids are green and holophytic (photo, autotrophic) like other plants. Few are nongreen, and saprobic like fungi and bacteria., , l, , l, l, , l, , l, l, l, , l, , l, , Some capture and ingest the organisms like animals, (holotrophic). Green forms have saprobic mode, pickup organic matter from outside (myxotrophic)., Holotrophic or phagotrophic nutrition is absent in, Euglena., Euglenoids store carbohydrates in the form of, paramylum chemically, distinct from starch and, glycogen., Reproduction is usually asexual by cell division, but sexual reproduction has been reported in one, genus., Under favourable condition, euglenoids reproduce, by simple, longitudinal binary fission., Flagellum disappears prior to division., Most of the species produce cyst having thick, stratified membranes with deep red colouration, due to synthesis of haematochrome., Besides cyst formation, many of nonflagellate cells, may get embedded in a common gelatinous sheath, resembling a palmella stage (as in algae)., Eg – Euglena, Paranema, Trachelomonas., , Slime moulds, l, Slime moulds are consumer decomposer protists., l, Asexual reproduction takes place through binary, fission, plasmotomy, spores, cyst and sclerotium., l, Sexual reproduction is isogamous or anisogamous., l, Both zygotic meiosis (cellular slime moulds) and, gametic meiosis (acellular slime moulds) occur., l, Slime moulds have characters of plants (cellulose, cell wall), animals (phagotrophic nutrition), and, fungi (spores). They take part in both, decomposition of organic matter and feeding of, other decomposer organisms., l, Slime moulds, therefore, live in contact with, organic matter., l, Slime moulds (500 sp.) have several features which, are animal like in their vegetative stages and plant, like in reproductive stages., l, The slime moulds are widely distributed, growing, in damp and shady places., l, They may be found in the soil rich in humus, damp, old planks of wood, rotting logs, decaying leaves etc., l, They prefer moisture and darkness or dimlight, for normal growth, they move to drier and exposed, habitats during reproductive phase., l, More than 100 species, have been reported from India., l, The vegetative phase of the thallus is a freeliving,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, █ĽňĹęŐŇ– ▓ŕŐŚĽřŚď, , l, l, l, , l, l, l, l, l, l, l, l, , l, l, , naked, multinucleated mass of protoplasm called, plasmodium., The plasmodium consists of diploid nuclei, lacks, cell wall and secretes lime., The plasmodium shows amoeboid movement by, producing pseudopodia., Chlorophyll is lacking, so these are generally, saprophytic, rarely parasitic causing abnormal, swellings upon the bodies of hosts., They reproduce by means of spores produced in, sporangia., The spores have cellulosic cell wall and are, produced through meiosis., The slime moulds are generally holocarpic., The spores germinate to produce myxamoebae or, biflagellated swarm cells behaving as gametes., The swarm cells fuse in pairs showing isogamous, types of sexual reproduction., Slime moulds may be colourless or variously, coloured like yellow, orange, brown etc., Slime mould are of two types – acellular and cellular., Acellular slime moulds have a wallless, multinucleate protoplasm or plasmodium without, (protoplasmodium) or with a number of branched, veins showing cyclosis (Phaneroplasmodium)., Multiplication occurs by plasmotomy., Normally when food is about to exhaust, the, , l, l, , l, l, , 23, , plasmodium comes to rest and develops sporangium., Each sporangium has a noncellulosic covering, called capillitium. Eg, Fuligo, Physarum., Cellular slime moulds are initially in the form of, haploid uninucleate wallless myxamoebae which, are surrounded by mucilage, move about by, pseudopodia and feed on bacteria and other micro, organisms through ingestion., Myxamoebae multiply by binary fission., Sexual reproduction occurs occasionally through, macrocyst formation. Eg. Dictyostelium,, Polysphondylium., , Protozoa, l, , l, , Protozoa (also included in the animal kingdom) are, unicellular organisms having varied form, structure,, and holozoic, saprobic or parasitic nutrition., Reserve food is glycogen, cysts occurs during, unfavourable condition. Asexual reproduction by, fission or budding and sexual reproduction by, conjugation or syngamy., Major groups of protozoans based on locomotary, organs are –, –, Zooflagellata (Flagellated protozoans), –, Sarcodina (Amoeboid protozoans), –, Ciliata (Ciliated protozoans), –, Sporozoa, [For more details refer chapter Protozoa]
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 24, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 5, , Fungi, Lichen and, Mycorrhiza, FUNGI, l, , l, l, , l, l, , The fungi (singular, fungus) are a group of, eukaryotic microorganisms that lack chlorophyll,, are unable to synthesize their own food and are, therefore, heterotrophic. They live either as, saprophytes, obtaining their food from the dead, organic matter, or parasites, obtaining food from, the bodies of living plants and animals., The term fungus is a latin word meaning mushroom., The branch of science that deals with the study of, fungi is called mycology (Greek word mykos =, mushroom and logos = discourse), and the branch, that deals with the study of fungal disease is called, fungal pathology., Clausius (1601) is regarded as the earliest writers, who described fungi., The founder of mycology is Antonio Micheli. He, gave the first systematic account of fungi in his, book Nova Plantarum Genera., , l, , l, l, l, , l, l, , General characters of fungi, l, l, l, , l, l, , l, , Fungi is very large group of over 100,000 species., Fungi are ubiquitous i.e occurs in a variety of, habitats., Most of them are moisture loving and terrestrial,, but a few are aquatic, e.g., Monoblepharis and, Saprolegnia and these are commonly known as, ‘water moulds’., A few fungi are epiphytic, live on trees, e.g.,, Armillaria on apple tree and causes red rot of apple., It is usually defined as a group of those organisms, which form the thallus (i.e., not differentiated into, root, stem and leaves), built up of single cell or, cells (unicellular or multicellular)., Fungi lack chlorophyll and are unable to synthesize, their own food by the process of photosynthesis., , l, , l, , l, , l, , Fungi obtain their nutrition from the external, source by the process of extracellular digestion, and absorption of the digested material., Such mode of nutrition is called heterotrophic, and the organisms are called heterotrophs., Heterotrophic organisms either live on dead, decaying organic matter or on living organisms., According to their mode of nutrition, fungi are, of two types – parasites and saprophytes., Parasite may be defined as “an organism existing, in an intimate association with another living, organism from which it derives an essential part of, the materials for its existence”. Thus, these, organisms grow on living organisms and obtain, their food from it., Parasitic fungi obtain their food from living hosts., These may be :, –, Ectophytic : These are externally on the host,, e.g., Erysiphe (Powdery mildew)., –, Endophytic : These are inside the tissue of, plants, e.g., Albugo, Phytophthora, Alternaria., Saprotrophs obtain their food from nonliving, decaying organic matter (such as bread, meat, fruit,, vegetables, animal dung etc.). Such mode of, nutrition is called saprophytic., Some fungi grow in symbiotic association with, algae to form lichens. Some other grow in close, association with the roots of higher plants and, form mycorrhiza., Fungi posses definite cell wall (containing cellulose, or chitin or both i.e., fungus cellulose) and true, nucleus (eukaryotic) but lack chlorophyll, (achlorophyllous) and differentiation of vascular, tissue (i.e. nonvascular)., They are spore forming and reproduce by, vegetative, asexual and sexual methods.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◘śňĹĽΘ– ▌ĽĘĺĚň– ďňę– ▐ťĘŐŕŕĺĽŮď–, l, l, l, l, l, l, , l, l, , l, l, l, , l, , l, l, , l, l, l, , l, , l, , The reserve food material is in the form of, glycogen and oil globules., Fungi grow well at 2030ºC and at acidic pH (6.0)., Fungi may be unicellular (yeast), much branch, filamentous (Rhizopus) type., The filamentous thread like structures that make, up the fungal body is called mycelium., Hyphae is the unit structure that make up the, mycelium (gk word hypha web)., Hyphae are of two types – aseptate or coenocytic, (multinucleate) and septate (number of partitions, or septa)., Aseptate hyphae may form septa during repro, duction, eg Rhizopus, Albugo, Phytophthora etc., In septate form cell may be monokaryotic, (uninucleate) or dikaryotic (two nuclei) or, multinucleate., Septa are of 3 types – complete septum, septum, with simple pore and septum with dolipore., In complete septum the cross wall is complete, without distinct pores, e.g., Geotrichum., In most ascomycetes and deuteromycetes, the septum, possesses simple central pore. Simple central pore, may get plugged by crystalline structure called, woronin body, e.g., trichomycetes. Woronin body, is secreted by microbody and covered by membrane., In basidiomycetes, the septum becomes barrel, shaped around a central pore called dolipore, septum, it may be surrounded by pore cap., Septal pores allow quick transport of nutrients from, the region of absorption to all parts of the mycelium., The reproductive hyphae are supplied with the, nourishment from the vegetative hyphae throughout, the septal pores., When mycelium is interwoven to form web like, structure it is called plectenchyma., It is of two types – prosenchyma and, pseudoparenchyma., Prosenchyma is the mycelium in which hyphae, are loosely interwoven and lie more or less parallel, to each other., Pseudoparenchyma is the mycelium in which the, hyphae are very loosely packed, so individual hypha, cannot be identified and appear as isodiametric cells, giving the appearance of parenchyma cells in higher, plants., When mycelium by interweaving forms compact, resting structure it is called sclerotium., , l, , l, , l, , l, , l, , l, l, l, l, , l, l, , 25, , When fungal mycelia are interwoven to form thick, cordlike structures like roots, that help in, absorption, it is called rhizomorphs., When the plant body is unicelled at one stage and, mycelial at the other end then the organisation is, described as dimorphic., When the entire mycelium is converted into, reproductive structure, the thallus is called, holocarpic., In eucarpic forms only a part of thallus become, reproductive. This can be monocentric (have single, sporangium) or polycentric (have many sporangia)., The hyphal wall is a made up of fungal cellulose, in which cellulose is impregnated with chitin and, contains nitrogen in addition to carbon and, hydrogen. Chitin is a polymer of Nacetyl, glucosamine., The protoplast is covered by a thin semipermeable, plasma membrane., The cytoplasm appear granular and contains many, minute nuclei scattered in the peripheral layer., The nuclei are very small and inconspicious., The cytoplasm contains many small vacuoles filled, with cellsap or a number of small gas filled, vacuoles., The vacuoles are small, few or absent in the actively, growing tips of the mycelium., The hypha also may be seen to have mitochondria,, dictyosomes (golgi bodies), ribosomes,, endoplasmic reticulum, oil drops and glycogen,, granules etc. under electron microscope., , Reproduction, l, l, , l, , l, , l, , l, , The fungi reproduce by all the three methods –, vegetative, asexual and sexual., Vegetative reproduction takes place by various, methods as fragmentation, fission, budding,, sclerotia, oidia and chlamydospores., In fragmentation, the hyphae of fungus break into, small pieces and each piece may later grow into, new mycelium., Fission is common in yeast. The cell divides into, daughter cells which separate by constriction or, transverse walls., In budding daughter bud appears from parent cell., After getting the normal size bud break off. When, the buds fail to separate, after repeated budding, from pseudomycelium., Oidia are rounded or oval structure having thin
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 26, , l, , l, l, , l, l, , l, , l, , l, l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , walls. The hyphae undergo segmentation and, produce yeast like cells called oidia. Each oidium, on germination produces new mycelium., Some fungi produce chlamydospores which are, thick walled resting cells. They are intercalary in, position. They are capable of forming a new plant, on approach of favourable conditions., Gemmae resemble chlamydospores in structure but, are not very durable and thick walled., Many true fungi produce sclerotia which are, hardened, resistant bodies. Sclerotia are capable of, surviving unfavourable periods and as soon the, conditions are favourable, they germinate to, produce vegetative hyphae., Asexual reproduction takes place by means of, spores., The spores in fungi vary in shape. Spores are usually, unicellular, thin walled, spherical and diameter, ranging from 550 m., Several types of spores are reported in fungi, eg., zoospores, sporangiospores, uredospores,, teleutospores, pycniospores etc., Sometimes the spores are produced endogenously, in special sac like asexual reproductive bodies, called sporangia., Spores in such cases are called sporangiospores., Zoospores are uninucleate, thin walled, formed in, zoosporangia. They may be uniflagellate, e.g.,, Synchytrium or biflagellate, e.g., Saprolegnia,Pythium., Biflagellate zoospores are of two types –, –, Pearshaped or pyriform, with 2 flagella, placed at anterior end, are known as primary, zoospores., –, Kidneyshaped or beanshaped, bearing two, oppositely directed flagella inserted laterally, in a furrow or concave side (secondary, zoospores)., Aplanospores are thin walled, nonmotile spores, formed inside sporangium, which give rise to new, mycelium, e.g., Rhizopus, Mucor., Conidia are nonmotile, thin walled exogenously, produced spores on a condiophore and sometimes, they are arranged in chains upon the conidiophore,, e.g., Aspergillus and Penicillium or singly in, Pythium, Phytophthora., Hyphae bearing conidia are called conidiophores., The conidiophores in groups may form structures, like acervuli, synnemata etc., , l, , l, , l, , l, l, , l, , l, l, l, l, l, l, l, , l, l, , l, , l, , Pycniospores are small conidialike bodies, produced in flaskshaped cavities called the pycnia,, e.g., Puccinia., Ascospores are uninucleate, unicellular nonmotile,, usually eight in number produced in saclike, structures called ascus, characteristic of, ascomycetes., Basidiospores, are, characteristic, of, basidiomycetes, produced exogenously by club, shaped basidium or sterigma. Usually four, basidiospores are produced., Uredospores and teleutospores are binucleate, spores produced in clusters called uredosori., Sexual reproduction in fungi involves three, process – plasmogamy (fusion of protoplast),, karyogamy (fusion of two haploid nuclei) and, meiosis., Fungi may be dioecious or unisexual some are, monoecious or bisexual. Former are heterothallic, and latter are homothallic., Fungi generally possess unicellular sex organs and, show gradual degeneration of sexes., Male gametangia is called antheridium. It is, smaller in size., Female gametangia is called oogonium which are, comparatively larger in size., The gametes are formed within gametangium., All three types of sexual reproduction is present in, fungi as isogamy, anisogamy, oogamy., In isogamy fusing gametes are exactly alike in, appearance and functions., Fusion of dissimilar gametes is called anisogamy., In anisogamous forms both fusing male and female, gametes are usually motile., Fusion of male gamete with female gamete is called, oogamy., In gametangial contact the two gametangia come, close to each other, but do not fuse. The male, gametangium sends a tubular outgrowth, called, fertilization tube, through which the nonmotile, male gamete or male nucleus migrates into the, female gametangium. Eg. Phytophthora, Albugo., In gametangial copulation two gametangia fuse, with each other and lose their identity in the sexual, act resulting in the formation of zygospore. Eg., Mucor, Rhizopus., In s pe r m a tiza tion s ome fungi produ ce, numerous, minute, uninucleate, sporelike
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 30, , l, l, l, , l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Boletus and Amanita spp.are poisonous fungi., The fungus that produces latex is Mycena., Mucor, Rhizopus, Penicillium, Neurospora,, Amanita, Polyporus are commonly called as pin, bread mould, bread mould, green mould, pink, bread mould, toad stools and brackett fungi, respectively., Spores of Rhizopus, Mucor, Aspergillus germinate, on jam, jellies, pickles, bread, etc., and destroy, them, Penicillium, Mucor and Aspergillus destroy, meat., Polyporus (Pore fungi) causes wood rot., Alternaria, Penicillium, Trichoderma, Mucor,, Chaetonium, Cephalothecium and Fusarium, destroy leather, cloth, rubber, paper, camera lenses,, etc., Aflatoxins are mycotoxins (harmful secretion), produced by Aspergillus flavus, A. fumigatus,, Penicillium islandicum, etc., These bind with DNA and prevent transcription,, hence protein synthesis. These cause liver cancer, in animals and men., In VAM the hyphae develop an arbuscule, (penetrate) within the cortex of root. It helps mainly, in phosphate absorption from the soil., , LICHENS, l, , l, l, l, , l, , l, l, , Lichens are formed by a symbiotic relationship, between algae or cyanobacteria and fungi, in, which individual photobiont cells are embedded in, a complex of fungal tissue., The number of lichen genera is 400 and species, over 15,000., The study of lichens is called lichenology., Body of the lichen is made of a fungus partner, called mycobiont and a photosynthetic algal partner, called photobiont or phycobiont., In 98% of the lichens, the mycobiont or fungal, partners belong to ascomycetes. Few lichen shows, basidiomycetes fungal partner also., Photobionts or phycobionts either belongs to, cyanobacteria or green algae., Photobiont performs photosynthesis, nitrogen, fixation and elaborates vitamins and other growth, substances while mycobiont takes part in, protective covering body, attachment, absorption, and retention of moisture from dew, rain and wet, air, and protection against harmful radiations., , –, –, –, , –, –, , –, , l, l, , l, l, , l, , l, , l, , l, l, l, , History of Lichen, The term lichen was first given by, Theophrastus for superficial growth on, bark of Olea europea (olive) tree., Morisson (1699) called lichen as musco, fungus., Schwendiner (1867) gave dual hypothesis, and established the composite nature of, lichen. He defined lichen as ‘fungi, parasitizing algae’., Bonnier (1886 89) successfully synth, esized a lichen by growing fungal spores, with algae., Reininke (1872) gave the term, ‘Consortium’ for the association of algae, and fungi. The term means mutual growth, and interdependence. De Bary (1879), termed this association as symbiosis., Crombic (1885) gave the term helotism i.e., master and slave relationship to the algal, and fungal association in lichen. Helotism, is the most accepted term used now a days, to describe this relationship., , Algae are present on the upper part of thallus and, fungi are present on the lower part of thallus., Fungal partner provides protection to algal partner, and are also responsible for the sexual, reproduction., Such a mutually beneficial relationship is called, symbiosis or mutualism., For proper diffusion of nutrients the algal cells and, fungal hyphal tips become surrounded by common, extracellular substance., At times, the mycobiont send haustoria into algal, cells, prevent alga to secrete pectic substances or, induces alga to secrete nutrients., Consequently, fungus is considered to be controlled, parasite. The phenomenon of controlled parasitism, is called helotism., As algae and fungi both contain cell wall which is, the characteristic feature of plant cell, so lichens, are considered as plants., About 12 genera of cyanobacteria and 21 genera, of green algae are considered as lichen symbiont., Important cyanobacteria are Nostoc, Gloeocapsa, and Rivularia., Green algae symbiont involves Protococcus,, Trentepohlia, Cladophora and Trebauxia.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◘śňĹĽΘ– ▌ĽĘĺĚň– ďňę– ▐ťĘŐŕŕĺĽŮď–, l, l, l, l, , Lichens generally grow on old walls, roof of house,, trunk of trees or exposed rocks., Lichen like Usnea hangs from the smaller branches, of trees., Lichen can withstand extreme of cold, heat and, drought., They are dominant form of vegetation in alpine, and arctic tundras., , Reproduction, l, l, , l, , l, , Reproduction may be vegetative, asexual or sexual., Vegatative reproduction occurs by –, –, Fragmentation – When thallus break into, small fragments develop into new lichen thalli., –, Soredia – Soredia are small masses of hyphae, enclosing a few algal cells. Soredia are, dispersed by air currents. Each soredium, develops into a new thallus., –, Isidia – They are superficial outgrowths, from the upper surface of the thallus. Isidia, consist of an external cortical layer and an, internal algal layer., Asexual reproduction, –, In some lichens pycnidiospores are produced, at tips of fertile hyphae inside pycnidium, which is a flask shaped structure, opening, through a pore called ostiole., –, These spores germinates to produce a fungi, mycelium., –, The fungal mycelium with corresponding alga, form new lichen thallus., Sexual reproduction, –, It is performed mainly by its fungal, component., –, Most of the lichens belong to the division, ascolichens, in which the fungal partners, belong to ascomycetes., –, The male reproductive organ is flask shaped, spermogonium which produces nonmotile, male gametes or spermatia., –, The female reproductive organ is, carpogonium which is differentiated into, basal coiled ascogonium and upper long tube, like trichogyne., –, The fruiting body ascocarp formed after, fertilization may be a apothecium type or, perithecium type., –, The bottom of ascocarp is lined by hymenium, which consists of asci in spread with paraphysis., , –, –, , 31, , The wall of ascocarp (apothecium or perithecium), is composed of the vegetative part of the thallus, consisting of algal and fungal layers., Each ascus contains eight ascospores which, germinate and form fungal mycelia., The mycelium when comes in contact with a, suitable alga, forms new lichen thallus., , Classification of lichens, l, , l, , l, , l, , On the basis of their fungal partner the lichens, are divided in two groups –, –, Ascolichens – Fungal partners belongs to, ascomycetes. Gymnocarpae, fruiting body is, apothecium type. Pyrenocarpae, fruiting body, is perithecium type., –, Basidiolichens – Fungal partners belongs to, basidiomycetes., On the basis of habitat lichens are –, –, Saxicolous : Rockdwellers and adapted to, xerophytic adaptation, eg. Xanthoria., –, Corticolous : Barkdwellers and grows in, adaptation of plenty of moisture, eg. Parmelia., –, Terricolous : Terrestrial species and thus, grows in soil, eg. Cladonia floerkeana., –, Lignicolous : Lichens which grow on wood, directly, eg. Cyphelleum., On the basis of thallus lichens may be –, –, Leprose lichens – The lichens are in the form, of minute scales, attached superficially over, the substratum, e.g. Lepraria incana., –, Crustose – Lichens are crustlike, closely, attached to substratum due to adhesion at, several points, eg. Graphis, Rhizocarpon., –, Foliose – Lichen body is like a crinkled and, twisted leaf, ie. flat, branched or lobed. It is, attached to substratum by one or a few points,, eg. Parmelia, Peltigera., –, Fruticose – The lichen shows branched, erect, or pendulous with bushy appearance, An, attaching disc is present at the base, eg., Ramalina, Cladonia, Usnea., –, Filamentous – The photosynthetic partner is, well developed and filamentous. It is covered, by a few fungal hyphae, eg., Racodium., On the basis of distribution of algal component, in the thallus lichens are of two types –, –, Homoisomerous thalli – Algal cells and, fungal hyphae are uniformly dispersed, throughout the thallus, eg. Collema.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 32, , –, , ŕďőĽę– ĐĽŐńŐĹť, , Heteromerous thalli – The algal cells are, found in algal zone only. The bulk of lichen, body is formed by fungal partner (mycobiont)., It includes the surface, medulla and rhizinae., The algal constituents hardly 5% of the lichen, body, eg Parmelia., , Economic importance of lichens, l, l, l, , l, l, l, l, l, l, l, l, l, l, , l, , l, l, l, l, , Fresh water species of lichen is Hymenelia lacustris, and marine water species is Caloplaca marina., Cladonia rengiferina, commonly called as reindeer, moss, is an important source of food for reindeer., Cetraria islandica, commonly called iceland moss, is used as source of food of sheep, cattle as well, as human., Everina used for making bread, Lecanora is also, edible., Lichen Evernia prunastri yields an excellent, perfume., Roccella, Parmelia, Evernia etc. are dye yielding, (orchil) lichen species., Litmus is obtained from lichen Roccella montaignei., Medicinal property of lichen is due to a substance, lichein., Usnic acid, an important broad spectrum antibiotic,, is obtained from Usnea and Cladonia., Xanthoria parietina is used against jaundice., Peltigera canina is used against hydrophobia., Cetraria is used as laxative., The protolichesterinic acid, obtained from some, lichen like Cetraria icelandica, has anticarcinogenic, properties., Lichens serve as indicator of air pollution, as, they are very sensitive to air pollution, especially, SO2 pollution., Crustose lichens are pioneers in xerosere, (succession beginning in dry condition)., In Russia and Sweden, some lichens like Cetraria, and Lecanora are used for alcoholic fermentation., Lichens secrete some organic acids which break, down rocks and thus help in soil formation., Some lichens are poisonous also due to various, substance present in them as :, Lichen, Poisonous due to, Letharia Vulpina, Vulpinic acid, Cetraria juniperina, Pinastrinic acid, Parmelia molluscula, Selenium, Xanthoria parietina, Beryllium, Everina fur furcea, Chlorine, , MYCORRHIZA, l, l, l, , l, , l, , l, , l, , Mycorrhiza is symbiotic relationship between fungi, and roots of higher plants., They are thick, irregular with wooly covering devoid, of root hair and root cap., In a mycorrhizal association, the fungus may, colonize the roots of a host plant either, intracellularly or extracellularly., This mutualistic association provides the fungus, with a renewable source of food through access to, fixed carbon (sugars) from the plant photosynthate., These are translocated to the root tissues from their, source location (usually leaves), and then to the, fungal partners. In return, the plant gains the use, of the mycelium’s tremendous surface area to absorb, mineral nutrients from the soil., The mycelia of mycorrhizal networks have better, mineral absorption capabilities compared to plant, roots., Mycorrhizal plants are often more resistant to, diseases, such as those caused by microbial soil, borne pathogens, and are also more resistant to, the effects of drought, perhaps due to the, improved water uptake capability of the fungal, hyphae., , Types of mycorhizza, l, , l, , The two most common types of mycorrhizas are, – the ectomycorrhizas and endomycorrhizas, (more commonly known as arbuscular, mycorrhizas)., The two groups are differentiated by the fact, that the hyphae of ectomycorrhizal fungi do not, penetrate the cell wall of the plant’s root cells,, while the hyphae of arbuscular mycorrhizal fungi, penetrate the cell wall., , Ectomycorrhizae, l, Ectomycorrhizas, typically form between the roots, of woody plants and fungi belonging to the divisions, basidiomycota, ascomycota, or zygomycota., l, These are external mycorrhizae that form a cover, on root surfaces and between the root’s cortical, cells., l, Besides the mantle formed by the mycorrhizae, most, of the biomass of the fungus is found branching, into the soil, with some extending to the apoplast,, stopping short of the endodermis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◘śňĹĽΘ– ▌ĽĘĺĚň– ďňę– ▐ťĘŐŕŕĺĽŮď–, l, , These are found in 10% of plant families, mostly, the woody species, including the Oak, Pine,, Eucalyptus, Dipterocarp, and olive families., , Endomycorrhizae, l, Arbuscular mycorrhizas, or VAM (formerly known, as VesicularArbuscular Mycorrhizas) involves, entry of the hyphae into the plant cell walls to, produce structures that are either balloonlike, (vesicles) or dichotomously – branching, invaginations (arbuscules)., l, In VAM the hyphae develop an arbuscule (penetrate), within the cortex of root. It helps mainly in, phosphate absorption from the soil., l, The fungus is generally a zygomycetes., l, The fungal hyphae do not in fact penetrate the, protoplast (i.e. the interior of the cell), but, invaginate the cell membrane., l, The structure of the arbuscules greatly increases, the contact surface area between the hypha and, , l, , l, , l, , l, , 33, , the cell cytoplasm to facilitate the transfer of, nutrients between them., Arbuscular mycorrhizas are formed only by fungi, in the division glomeromycota, which are typically, associated with the roots of herbaceous plants, but, may also be associated with woody plants., Arbuscular mycorrhizas are likely to be very helpful, in protecting plants from adverse conditions such, as lack of water and nutrients., Arbuscular mycorrhizal fungi are quite, extraordinary organisms. First they have been, asexual for many million years and secondly,, individuals can contain many genetically different, nuclei (a phenomenon called heterokaryosis)., This type of association is found in 85% of all, plant families in the wild, including many crop, species such as the grains., [For more on mycorrhiza refer chapter Pesticides, and Biofertilizers]
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 34, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 6, , Plant Classification, l, l, , l, , l, l, l, , l, , l, , l, , l, , Plant classification is arrangement of plants into, groups and subgroups on the basis of affinities., In the two kingdom classification, plants comprise, all the photoautotrophic organisms and their non, photosynthetic relatives which have absorptive type, of nutrition, a wall around the cells and all groups, of algae, besides the embryophytes., In five kingdom classification, plant kingdom, comprises only embryophytes and some eukaryotic, algae., Bacteria, blue green algae, euglenoids, diatoms,, dinoflagellates and fungi are excluded., Kingdom Plantae includes all multicellular,, eukaryotic, photosynthetic organisms., Main characters of this kingdom are –, –, With definite cellulosic cell wall., –, These are basically nonmotile, excepting, some aquatic forms., –, Reproduction is primarily sexual., –, Presence of definite chloroplasts, –, Photosynthetic mode of nutrition (oxygenic, photosynthesis), eg. different types of algae, (green, brown, red algae), bryophytes,, pteridophytes, gymnosperms and angiosperms., In traditional system of classification (Eichler,, 1883), plant kingdom is divided into two, subkingdoms – cryptogamae and phanerogamae., Plants included under cryptogamae are called, cryptogams while those placed in phanerogamae, are known as phanerogams., Cryptogams (Gk. cryptos – hidden, gamos, marriage) do not bear conspicious reproductive, structures like seeds. Therefore, they are called, lower plants or seedless plants., Cryptogams have three divisions – thallophyta,, bryophyta and pteridophyta., , l, , l, , l, , l, , l, , Thallophyta, –, Plant body not differentiated into root, stem, and leaves., –, They do not have well developed conducting, tissues., –, Sex organs are simple., –, Thallophyta includes – algae, fungi., –, Algae : Green, autotrophic thallophytes, e.g., Spirogyra, Ulothrix. etc., –, Fungi : Nongreen (achlorophyllous), thallophytes having heterotrophic mode of, nutrition, e.g. Albugo, Mucor, yeast etc., [Discussed under Fungi chapter], Bryophyta, –, Plant body gametophytic, thalloid or foliose., –, Rhizoids present instead of roots., –, Conducting tissues absent or represented by, thick walled cell. (eg. Funaria)., –, Sex organs are multicellular and jacketed., Pteridophytes, –, Plant body sporophytic, differentiated into, root, stem and leaves., –, Xylem and phloem are conductive tissues, hence called vascular cryptogams., –, Reproduce by spores., –, Sex organs are like those of bryophytes., –, Embryo is always present., –, Sporophytic and gametophytic phases are, morphologically distinct., –, Show regular alternation of generation., Phanerogams (Gk, phanerosvisible, gamos, marriage) have evident reproductive structure in, the form of seeds. Therefore, they are called as, seed bearing plants., Phanerogams have two divisions – gymnosperms, and angiosperms.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 36, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 7, , Algae, l, l, l, l, l, , The word algae was coined by Linnaeus (1753)., The branch of botany dealing with the study of, algae is called as phycology or algology., Term phycology is derived from the Greek word, phykos which means ‘alga’ or “sea weed”., Algae are defined as chlorophyllous, thalloid,, avascular plants with no cellular differentiation., A plant body that is not differentiated into a root, , l, l, l, , stem and leaf is known as thallus., Algae contains about 18,000 genera and 29,000, species., Structure and reproduction of algae was written by, Fritsch. He is known as Father of algae., Fritsch divided algae into 11 classes on the basis, of type of pigments, nature of reserve food, material and mode of reproduction., , Table : The distinctive features of the major 11 classes of algae, Class, Major photosynthetic pigments Reserve food, Number of flagella & their, material, arrangements, 1. Chlorophyceae, Chl. a & b + carotenoids and True starch and Vegetative or gamete cells, sugar, xanthophyll, with two or four equal flagella, 2., , Xanthophyceae, , Two flagella of unequal, length, Flagella when present one or, three, Flagella absent, , 5., , Xanthophylls & bcarotenes +Chl. Oil or leucosin, a&e, Chrysophyceae, carotene, fucoxanthin, lutein + Leucosin, rarely oil, Chl. a, Bacillariophyceae Diatoxanthin, diadinoxanthin, Oil, volutin, fucoxanthin + Chl. a & c, Cryptophyceae, Chl. a and c, carotenes, Starch, , 6., , Dinophyceae, , Flagella two, lateral in, position, Flagella two, apical or, subapical, Number variable in Euglena, , 3., 4., , 7., 8., , 9., , xanthophylls, Chl. a & c, xanthophylls Oil & starch, (diadinoxanthin, dinoxanthin), Chloromonadineae Chlorophylls, xanthophylls, Fatty substance or, oil, Euglenophyceae Chl. a & b, carotenes, Paramylum a starch, like substance but, negative to iodine test, Phaeophyceae, Fucoxanthin, flavoxanthin, Laminarin, mannitol, bcarotenes + Chl. a and c, , 10. Rhodophyceae, 11. Cyanophyceae, , Two unequal flagella, interior end, , at, , In gametes flagella two,, unequal and lateral in position, , Phycoerythrins + Phycocyanin + Floridean starch, Absent, Chl. a and d, Phycocyanin, Phycoerythrin & C y a n o p h y c e a n Absent, starch, chlorophyll
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 38, , l, l, l, l, , l, , l, , l, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Asexual reproduction occurs through zoospores,, hypnospores, akinetes, endospores or cysts etc., Asexual reproduction occurs in favourable, condition (by mitospores)., Under unfavourable conditions algae reproduce, sexually., Depending upon the size of gametes the sexual, reproduction is of two types isogamous and, heterogamous (anisogamous, oogamous)., Isogamy occurs commonly in unicellular algae,, e.g. Ulothrix. Here the male and female gametes, are morphologically similar but differ in, physiology., Anisogamy is the fusion of gametes where male, gametes are comparatively smaller in size and more, active than female gametes which are larger and, sluggish, e.g. Chlamydomonas brausii., Oogamy is the most advanced type of sexual, reproduction. Here the male gametes are motile, and formed in large numbers whereas female, gametes are nonmotile and bigger in size., Male gametes are produced in antheridium, whereas female gametes are produced in oogonium., Some special complex type of reproductive bodies, found in Rhodophyceae are called spermatium and, carpogonium., Water is the suitable medium for the fusion of, gametes during sexual reproduction., Fusion of male and female gametes occur and, zygote is formed., , Salient features of some selected classes, Chlorophyceae (green algae), l, Plants fresh water or marine, l, The structure is various unicellular motile, (Chlamydomonas) nonmotile (Chlorella), colonial, (Volvox, Hydrodictyon), parenchymatous (Ulva),, coenocytic (Volvox), l, Cell wall is composed of cellulose., l, Chief pigments – chlorophyll a, b, a, b, g – carotenes,, lycopene, lutein, galaxanthin., l, Reserve food – starch and oils., l, Asexual reproduction by zoospores, aplanospores, and hypnospores., l, Male gamete flagellate, l, Flagella identical., l, Sexual reproduction – isogamous, anisogamous or, oogamous., l, E.g. Chlamydomonas, Spirogyra., , Xanthophyceae (yellow green algae), l, Plants generally fresh water, l, Forms unicelled to simple filamentous., l, Chief pigments – chlorophyll a, e; bcarotene,, violaxanthin, neoxanthin., l, Reserve food – chrysolaminarin and oils., l, Zoospore formation occurs., l, Male gametes flagellate, flagella nonidentical, (unequal)., l, Sexual reproduction – isogamy, anisogamy or, oogamous., Phaeophyceae (brown algae), l, Plants marine (exceptfew), l, The body is differentiated into 3 parts – holdfast,, stipe and lamina., l, They have holdfasts for attachment but Sargassum, and Fucus become free floating. North Atlantic, ocean is often called Sargasso Sea because of the, abundant growth of Gulf Weed or Sargassum., l, Some brown algae are very large. They are called, trees of seas or kelps. Depending upon the size,, kelps are differentiated into giant kelps (e.g.,, Macrocystis 40 – 60 m; Nereocystis 20 – 30 m) and, small kelps., l, Cell wall contains cellulose and phycocolloids, (alginic acid)., l, Asexual reproduction by fragmentation and spores., l, Cells showing eukaryotic organization., l, Chief pigments – chlorophyll a, c; bcarotene,, fucoxanthin (for brown colour), lutein,, violaxanthin, diatoxanthin., l, Reserve food – laminarin, mannitol, fats and oils., l, Male gametes flagellate, flagella unequal (tinsel, and whiplash), lateral., l, Sexual reproduction – isogamy, anisogamy or, oogamous., l, Life cycle is diplohaplontic (eg Dictyota) or, diplontic., l, Eg Fucus, Sargassum, Laminaria etc., Rhodophyceae (red algae), l, Plants generally marine., l, The plants are simple filamentous to attaining, complexity of structures., l, Some cells show protoplasmic or pit connections., l, Chief pigments – chlorophyll a, d; a, bcarotene,, lutein, violaxanthin, fucoxanthin, myxoxanthin,, rphycoerythin, rphycocyanin, and allophycocyanin.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 39, , ○ńĹďĚ–, l, l, l, l, l, l, l, , Red colour is due to phycoerythrin., Reserve food – floridean starch, galactan SO4,, polymers., No zoospore formation., Male gametesnon flagellate., Sexual reproduction by special type of oogamy., Life cycle haplobiontic or diplobiontic,, E.g. Batrachospermum, Gelidium., , Myxophyceae or Cyanophyceae (blue green algae), l, Plants generally freshwater, a few forms marine., l, Forms unicelled to filamentous. Cell wall made up, of mucopeptide., l, Possess some specialised cells called heterocysts., l, Cells showing prokaryotic organization., l, Chief pigments – chlorophylla, bcarotenes, luteins,, xanthophyll, oscillaxanthin, callophycocyanin,, allophycocyanin., l, Reserve food – cyanophycean starch (glycogen), and cyanophycin (protein)., l, No zoospore formation., l, No flagellate bodies., l, No sexual reproduction., l, E.g. Nostoc, Oscillatoria, Anabaena., , l, , l, , Life cycle patterns found in algae, l, , l, l, l, , l, , l, l, , It is recurring morphological and cytological phases, in an organism that occur in each individual from, its birth to death., It is of following types – haplobiontic, diplobiontic, and triplobiontic., Haplobiontic : Only one somatic phase is present., It is of two types – haplontic and diplontic., Haplontic is a single somatic phase which is, haploid. Diploid condition is present only in zygote, or zygospore wherein meiosis occurs to produce, haploid condition again, e.g., Spirogyra,, Chlamydomonas, Ulothrix, Chara. Alternation of, generations is absent., Diplontic is a single somatic phase which is diploid., Haploid condition occurs in gametes (formed, through meiosis) which fuse to restore diploid state,, e.g., Cladophora glomerata, Bryopsis, Fucus,, Sargassum. Alternation of generations is absent., Diplobiontic. Two somatic phases are present in the, life history – diplohaplontic and haplohaplontic., Diplohaplontic. Both haploid gametophytic and, diploid sporophytic somatic phases occur in the, life history. It has two subtypes :, , Isomorphic, or, monomorphic, diplohaplontic : Gametophytic and, sporophytic phases are morphologically, similar though cytologically they are, haploid and diploid respectively, e.g.,, Dictyota, Ulva. There is an isomorphic or, homologous alternation of generations., – Heteromorphic, or, dimorphic, diplohaplontic : Haploid and diploid, phases are morphologically dissimilar. One, of them is dominant. A heterologous or, heteromorphic, alternation, of, generations occurs, e.g., bryophytes, (gametophyte dominant), pteridophytes, (sporophyte dominant)., Haplohaplontic. Only haploid cytological stage is, present in two somatic phases, e.g., Porphyra, (dimorphic haplobiontic or diphasic haplohaplontic)., Triplobiontic. Three somatic phases occur., –, Haplohaplohaplontic. Three haploid phases, occur in the life history., –, Diplodiplohaplontic. Triphasic or trimorphic, life history with two diploid and one haploid, stages, e.g., Polysiphonia., –, , SOME IMPORTANT EXAMPLES, Chlamydomonas, l, , l, l, l, , l, , l, , Chlamydomonas is a free living aquatic unicellular, and flagellate green alga (10 – 30 µm) that occurs, in ammonium rich fresh water., Excessive growth of Chlamydomonas may impart, green colour to water., Cell wall does not contain cellulose. Instead, glycoprotein is present., Internally the alga contains a single nucleus, two, contractile vacuoles for osmoregulation and excretion,, a basin or cupshaped chloroplast with a red eye spot, or stigma and a pyrenoid for storage of starch., Asexual reproduction occurs through zoospore, formation, palmella stage, aplanospores and, hypnospores., Palmella stage is produced in response to toxic, chemicals and unfavourable water conditions., Here the cells lose flagella and enclose themselves, in mucilage. They, however, continue to grow and, divide. On being flooded with water or removal of, toxic chemicals, the mucilage dissolves and each, cell forms a flagellate individual.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 40, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Sexual reproduction involves fusion of two, compatible gametes., Life cycle is haplontic., , Ulothrix, l, , l, , l, l, , l, l, , l, l, , Ulothrix is an unbranched filamentous green alga, of fresh aerated waters which is covered by a thin, sheath of mucilage. Lowermost cell is colourless, and functions as holdfast., Cell wall consists of two layers. Inner layer is made, up of cellulose and outer layer is mostly made up, of protopectin which is insoluble in water., Due to presence of protopectin, Ulothrix filaments, appear as wet threads., Asexual reproduction occurs through, fragmentation, zoospores, palmella stage,, aplanospores, hypnospores and akinetes. Only, green cells take part in reproduction., Sexual reproduction occurs through isogamy, (fusion of similar gametes)., Gametes are biflagellate and produced like, zoospores. The fusion product is diploid zygote, which forms a resting diploid zygospore., Under favourable conditions, meiosis occurs in the, zygospore., Life cycle is haplontic as dominant phase in life, cycle is haplophase (n) and diploid phase is, represented only by zygote or zygospore which, undergoes meiosis (reduction division) during its, germination., , Volvox, l, l, l, l, , l, , l, , Volvox is a fresh water green colonial algae first, observed by Leeuwenhoek (1700)., Volvox is a small hollow green ball of 0.5 – 2.5 mm, diameter which is popularly called rolling ball., The algae rotates on its axis during swimming., Reproduction is both asexual and sexual. The, reproductive cells or gonidia usually occur in the, posterior part., Asexual reproduction occurs through the, formation of daughter colonies. Each gonidium, can form a daughter colony., Sexual reproduction is oogamous. Colonies may be, monoecious or dioecious. In monoecious forms, the, male and female sex cells mature at different times., , Chlorella, l, , Chlorella is a nonmotile (nonflagellate), unicellular green alga which occurs in diverse, , l, l, , l, , l, , aquatic habitats, preferably rich in organic matter., Wall contains cellulose. It is three layered. Outer, layer may have sporopolleninlike material., Sexual reproduction is not known. Asexual, reproduction occurs through autospores. Here, divisions of the parent protoplast forms 2 – 32, daughter protoplasts, each of which develops a wall, and gets transformed into an autospore., Chlorella can be used as food because it is rich in, proteins (50%), carbohydrates (20%), vitamins (A, C,, K, B1, B2, B12) and minerals. It contains an antibiotic, chlorellin but can be also cause allergic asthma., Chlorella is used as experimental plant for, physiological records. It is an important, component of sewage oxidation tanks., , Spirogyra, l, , l, l, , l, , l, , l, , l, l, l, l, , l, , Spirogyra is an unbranched filamentous green alga, of stagnant fresh waters which forms floating, masses called pond scum., Spirogyra is also called pondsilk, water silk or, mermaids tresses., Cell wall consists of two distinct layers. The inner, layer is of cellulose and the outer is of pectose, which gets changed into pectin and this pectin, dissolves in water to form a slimy or mucilaginous, sheath. (It is sometimes referred to as third layer.), The protoplast is differentiated into plasma, membrane, cytoplast, nucleus, chloroplast with, pyrenoids and a large central vacuole., Pyrenoids are situated in the chloroplasts. They lie, equidistant from one another and are the centres, of starch formation., All the cells in the free floating species of Spirogyra, are alike, no differentiation into apex and base., Each cell can synthesize its own food, respire, divide, and reproduce. Thus the organism may be looked, upon as a ‘colony of independent cells’., Spirogyra is autotrophic., Growth in Spirogyra is intercalary or diffused., In Spirogyra reproduction takes place by three, methods – vegetative, asexual and sexual., Under exceptionally favourable conditions, Spirogyra multiplies by the method of, fragmentation., Fragmentation may be brought about in the, following ways –, –, Through accidental breaking resulting from, mechanical injury.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 41, , ○ńĹďĚ, , –, , l, , l, , l, , l, , l, , l, , l, , l, l, , Softening and subsequent dissolution of, middle lamella of the septa., –, Due to sudden change in the temperature and, acidity of water., Normally asexual reproduction is absent in, Spirogyra. It takes place only in some species. It, is of 3 types –, –, By aplanospores, –, By azygospores (parthenospores), –, By akinetes, Sexual reproduction takes place towards the end, of growing season usually in the late spring. It, commences when the filaments are well mature, and have stored sufficient food. The external, conditions which favour the process are :, –, Nitrogen deficiency., –, The change in pH of the aquatic medium on, alkaline side., The sexual reproduction in Spirogyra is called, conjugation. It involves the fusion of two, morphologcally identical but physiologically, dissimilar nonciliated gametes., The fusion of these gametes takes place by the, following 2 methods., –, Scalariform conjugation., –, Lateral conjugation., Scalariform conjugation (in both monoecious or, dioecious) takes place during the night and, between the recently divided cells of the conjugating, filaments., The conjugation tube between the two filaments, looks like a ladder, through which gamete from, one of the gametangia passes through to fuse with, the passive gamete of another filament. The gametes, are formed singly and both active and passive, gametes are considered male and female gametes, respectively. The fusion of both kinds of gametes, with each other results into formation of zygospore., Lateral conjugation (monoecious species) takes, place between two nearest cells of the same, filament. Both male and female gametes are found, in same filament., It is of two types – indirect lateral conjugation, and direct lateral conjugation., Life cycle in Spirogyra is haplontic as dominant, phase in life cycle in haploid (n) and diploid phase, is represented by only zygospore and it undergoes, R.D. or meiosis (zygotic meiosis)., , ECONOMIC IMPORTANCE OF ALGAE, Beneficial aspects, Algae as food and fodder, l, Sea weeds, especially brown algae, are used as food, for domestic animals in different parts of the world, and their wide scale usage centres in countries like, Norway, Scotland, France, Great Britain,, Scandinavia, America, New Zealand, etc., l, Pelvetia canaliculata is used as food for young, livestocks. Sargassum, Fucus and Laminaria are, eaten by cattle in Scotland and Island. Macrocystis, spp. and other kelps being rich in vitamins A and E, are served as cattle fodder., l, The marine algae are of considerable importance, in food value. They are often mixed with rice and, fish and served as base for soups, condiments and, eaten alone as salads. The edible forms are called, Limu in Hawaii, Tsao in China and Rimu in Tahiti., l, Chlorella is rich in protein and carbohydrates., l, Spirulina platensis is one of the richest sources of, protein, containing 4050 percent crude protein on, dry weight basis which under favourable condition, may reach upto 70 percent., l, The mucoprotein constituents of cell wall are easy, to digest and thus making Spirulina a good item, for both, human beings and animals., l, Algae serves primary food for fishes and other, small aquatic animals. Such algae may be both a, plankton or an attached form in the sea as well as, in fresh water., l, In fresh water lakes and ponds, Oedogonium,, Spirogyra, Microspora, Ulothrix, Cladophora,, Pithophora, etc, serve directly as fish food., Algae in industries, l, Alginic acid derivatives are extracted from the members, of Phaeophyceae such as Laminaria, Ascophyllum,, Macrocystis, Ecklonia, Lessonia, Durvillea., l, Carrageenin is the most famous carbohydrate, mucilage named after Irish village Carrageenan., The gelatinous carbohydrates are variously used, with puddings, eaten with milk or mixed with fruit, and even in ice cream. It is also used as clearing, agents in beer preparation. It is extracted from, red alga Chondrus crispus – “Irish moss” and to, a lesser extent from Gigartina spp., l, Agar, dried gellike nonnitrogenous extract from
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 42, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , red algae, is used as a medium in the cultures of, bacteria, fungi and algae and also in numerous, industrial processes. Agar was largely prepared, from Gelidium. Algae such as Camplaephora,, Pterocladia, Gracilaria, Ahnfeldtia, Eucheuma,, Chondrus, Gigartina, Phyllophora, Furcellaria are, used for extraction., Brown algae like Laminaria digitata, Ecklonia,, Easenia and Fucus spp. are largely known for the, extraction of iodine., Other micronutrients useful for human consumption, such as iron, copper, manganese and zinc have been, found in sea weeds., Diatoms and their large sedimentary deposits, “diatomaceous earth” are quite useful in industry., Diatomite is used in industrial filtration, processes, sugar refining and brewing industries., , Medicine and antibiotics, l, Because of high iodine content brown algae are, used in various goiter medicines, either mixed or, directly as a powder., l, Laminaria stipes are used as surgical tool in the, opening of wound owing to its property of gentle, swelling subject to moisture exposure., l, Chlorellin is extracted for Chlorella which inhabits, growth of certain bacteria and a few algae., l, Microcystis is popularly known for its inhibitory, action to Staphylococcus and Chlostridium and, zooplanktons such as Daphnia and Cyclops., , research carried on Chlorella (unicellular green, alga)., Algae in space travels, l, A spaceman will need a device to get rid of CO2, and other body wastes and will require sources of, O2 and food. So Chlorella, Synecoccus, etc., are, useful for this purpose and they grow very quickly., , Harmful aspects, l, , l, , l, , l, , Water purification, l, In water reservoirs, the larger growth of algae creates, great nuisance but lesser growth of algae acts as, biological filters by forming a microzone of the sand, surface which together with bacteria and fungi forms, a mucilage layer. By this microzone, harmful bacteria, are trapped and water also gets aerated., Sewage disposal, l, The presence of algae facilitates oxygenation of, sewage to a great extent. The algae known to grow, in sewage are Euglena, Chlorella, Scenedesmus,, Chlamydomonas, Pyrobotrys, Microactinum, etc., Algae in biological research, l, Recent knowledge of photosynthesis is based on, , l, , A compound toxin produced by certain algae proves, fatal to fishes, e.g. the growth of Aphanizomenon, and Microcystis aeruginosa in fish ponds are, poisonous to Crappis perch and Gambusia,, respectively., A few bluegreen algae such as Microcystis,, Anabaena, Nodularia, Gloeotrichia and, Aphanizomenon produce exotoxin and endotoxin, causing death of animals, horses, cattle, sheep, etc., Several cases of human death have been reported, as a result of indirect consumption of dinoflagellates, through fishes which have eaten them., The pollution caused by algae is well known. They, produce effective problems in water supply and, purification and become obnoxious in water, reservoirs, rivers and oceans. Some bluegreen and, green algae grow over the surface of water bodies, in abundance, especially in rainy season, and cause, water bloom. On death and decay, these algae give, bad smell. Some dinoflagellates (members of class, dinophyceae of algae) secrete poisonous or toxic, substances., –, Important algae causing water bloom are, Microcystis, Chroococcus, Oscillatoria, etc., These deplete the water of O2 and hence, animals like fish are killed., –, Marine algae growing in abundance retard the, speed of ships., India suffers enough serious problem of bluegreen, algae causing threat of enormous loss to Indian, Government revenue by effecting the quality of salt in, Sambhar lake in Rajasthan. Algae (such as Arthrospira), produce an offensive smell, impart pink rust red colour, to the salt and turn brine into a gelatinous fluid making, it impossible to develop crystals.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ŕťŐő坌Ěř–, , 43, , Chapter 8, , Bryophyta, l, , l, l, , The division Bryophyta (Greek : Bryon = moss;, phyton = plants) includes the simplest and primitive, land plants., It occupies a position inbetween algae and, pteridophyta., The group consists of about 960 genera and over, 25,0 00 species, occurring worldwid e in, distribution., Ø, Ø, Ø, Ø, Ø, Ø, , The term Bryophyta was used by Brown., The term moss coined by Jussiau., Hedwig is the father of Bryology., S.R. Kashyap is the father of Indian Bryology., The pteridophytic origin of bryophyte was, founded by Scott., The algal origin of bryophyte was founded by, Bower., , Characteristic features, l, , l, l, l, l, , l, , l, , The bryophytes are fundamentally terrestrial, plants but required presence of water to complete, their life cycle, because they require a moist soil, surface for swimming of their sperms and supply, of water to all parts., Thus, due to peculiar type of their habitats, they are, regarded as “the amphibians of the plant kingdom”., Bryophytes are first amongst land plants which, occur in damp and shady habitats., Dominant plant phase in bryophytes is free living, thalloid gametophyte., The gametophyte is thalloid in primitive forms, (Riccia) and differentiated into rhizoids, stem and, leaves in higher bryophytes (mosses)., From the lower surface of the thallus or from the, base of the stem, number of unicellular or, multicellular rhizoids arise. They are the organs, of absorption and fixation., Many bryophytes, eg. Riccia, Marchantia etc have, scale on ventral surface. Scales are multicellular, , l, l, l, l, l, , l, l, l, , and to protect the growing point or apical cell of, the thallus., The plant body has epidermis for protection., The thallus has air pores. Moss capsule has stomata, for gaseous exchange., Nutritionally, the plant body is independent and is, the conspicuous phase of the life cycle., The gametophytes lack vascular tissues namely, xylem and phloem., Stem, leaves and rhizoids of the bryophytes are, analogous to the stems, leaves and roots rather, than root hairs of vascular plants., Scales or amphigastria occur which take part in, capillary conduction and protection., The higher bryophytes (eg. Moss) have primitive, vascular strands (conducting tissues)., They reproduce by vegetative and sexual methods., , Vegetative reproduction, l, Vegetative reproduction occurs by various methods, to give rise to new thallus., l, Death and decay of the thallus – The older thallus, starts dying from lower to upper side. Finally the, growing point gets separated and formed fragments, develops into a new thallus., l, Adventitious branches – Detached from thallus, to form new thallus, e.g. Riccia., l, Tubers – These form during adverse condition, eg., Anthoceros., l, Gemmae – Marchantia thallus has cup like, structure, called gemma cup, which bears large, gemmae (multicellular)., l, Primary protonema – Spores on germination give, rise to primary protonema which breaks up into, segments that give rise to leafy gametophore., l, Secondary protonema – Protonema formed from, structures other than spores and give rise to leafy, gametophore.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 44, , ŕďőĽę– ĐĽŐńŐĹť, , Sexual reproduction, l, The sexual reproduction is of oogamous type. The, sex organs are called antheridia (male) and, archegonia (female). They are multicellular and, surrounded by a sterile jacket layer., l, Antheridium, –, It is stalked (multicellular) pear shaped structure., Its one cell thick jacket surrounds large number, of fertile cells called androcytes. Each androcyte, metamorphoses into a biflagellate antherozoid, or male gamete or sperms., –, Antherozoids are naked, biflagellate and, motile. The flagella are long, anterior and, whiplash type. They need water for, fertilization., l, Archegonium, –, Archegonium appears first time in, Bryophytes in plant kingdom., –, It is a flask shaped structure with swollen base, called venter and upper elongated neck., –, The archegonium is surrounded by one celled, thick sterile jacket layer., –, The venter contain a ventral canal cell and an, egg cell., –, The neck, made of 4–6 vertical rows of cells,, enclosing naked neck canal cells., –, The tip of neck has 4 covercells or lid cells., –, During fertilization the cover cells open and, neck canal cells and venter canal cell, disintegrate to form mucilage which absorb, moisture to create pressure which remove lid, cells and mucilage comes out of neck., –, Thus passage is formed for the entry of, antherozoids to fertilize the egg., Sporophytic generation, l, Sporophytic generation starts with zygote. The, zygote immediately secretes cellulosic wall, to, develop into embryo or sporophyte., l, The embryo is multicellular. The gametophyte, provide protection and nourishment to the, developing embryo., l, The development of embryo is exoscopic, i.e. first, division of zygote is transverse and the capsule, develops from outer or epibasal cell., l, The embryo is not liberated but is retained within, the archegonium where it develops into sporophyte., Sporophyte or Sporogonium, l, The sporangium develops from embryo. It does not, , l, , l, l, , l, , l, l, , l, l, , l, , has rhizoids, stems and leaves. It is permanently, attached to gametophyte and is completely, dependent on it., But in some Bryophytes like Anthoceros, mosses,, the sporophyte wall has photosynthetic tissues., Mostly the sporophyte consists of foot, seta and, capsule. The foot is an anchorage and absorptive, organ and remain embedded in gametophyte., The seta is small (Marchantia) to long (mosses) to, conducts food from gametophyte to capsule., The terminal capsule is either spherical or elongated., Capsule also surrounded by its own jacket, (sporophytic in nature) and 2 layered calyptra. The, calyptra originate from venter wall, hence, gametophytic in nature. The capsule contains large, number of spores or meiospores and elaters (absent, in Riccia). The spores are haploid and wind, disseminated. The meiosis is sporogenic., The elaters are sterile and are diploid. They have, hygroscopic thickening which helps in dispersal, of spores., The haploid spores, germinate to form young, gametophyte., In mosses, the spores first develop into multicellular,, haploid branched filamentous structure called, protonema, which later gives rise to gametophytic plant., The spores are of one kind, hence the bryophytes, are homosporous., All bryophytes exhibit heteromorphic alternation, of generations i.e., the individuals of each, generation are dissimilar., Bryophytes resemble pteridophytes in having, embryo stage, cuticle, multicellular sex organs with, sterile jacket, multicellular sporangia, oogamous, reproduction, flagellated male gametes etc., Similarities between algae and bryophytes, Ø Both are autotrophic, the plant body is, gametophytic., Ø Plant body is thallus like and devoid of, vascular tissues., Ø Root is absent but rhizoids are found for, attachment and absorption purpose., Ø Both algae and bryophytes have motile sperms, and need water for fertilization., , Classification of bryophyta, l, , Bryophytes have been divided into three classes –, hepaticopsida, anthocerotopsida and bryopsida.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 46, , l, l, l, l, l, l, l, l, l, l, l, l, l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The gametophyte is differentiated into prostrate, protonema and an erect gametophore., Gametophore is foliose., Rhizoids are multicellular with oblique septa., The stem is erect, leafy and bears radially, symmetrical sexual branches., The leaves are arranged in 38 rows on the stem., Each leaf shows a central midrib only., Sex organs develop near the tips of sexual, branches., The sporophyte is differentiated into foot, seta and, capsule., Sporogenous tissue may be formed from the, endothecium or amphithecium., Columella is present. It develops from endothecium., Peristome teeth are present in one or two rows and, surrounds the terminal opening of the capsule., Elaters are absent., The sporophyte is semiparasitic (as the sporophyte, is not completely embedded in the gametophyte., The spores on germination produces multicellular,, branched, chlorophyllous structure called, protonema., Leafy gametophores grow from protonema, eg., Funaria, Polytrichum, Sphagnum etc., The sex organs of Funaria are of projecting type, and stalked. They are mixed with sterile hair called, paraphyses., A cluster of vegetative leaves surrounds the sex, organs., The capsule of Funaria is distinguishable into an, upper opercular region, middle fertile or theca, region and lower apophyseal region., The opercular region is distinguishable into, operculum covering peristome which comprises, sixteen outer and sixteen inner teeth. The outer, teeth are thick and hygroscopic., , l, l, , l, l, l, , l, l, , The annulus separates operculum from theca, region., The fertile region mainly comprises archesporium, lined by outer and inner spore sacs. The central, sterile region is columella., The apophyseal region has central conducting, strands and stomata in the epidermis., The archesporium forms spore mother cells which,, by meiosis, form tetrahedral tetrads of spores., When the capsule is mature, the operculum is removed, along the annulus and the spores are dispersed by the, hygroscopic action of peristomal teeth., The spore forms the chloronema which gives rise, to caulonema., Capsule has columella., , Economic importance, l, l, , l, l, , l, l, l, l, l, l, , Sphagnum is most economically important, bryophyte., The bryophytes help in conservation of soil, soil, development and in succession of plant, communities., They are used in manufacture of paper, fabrics,, artificial wood etc., It is used in horticulture and added to soil to, improve its water holding capacity. It is used as, packing material for living plants., Peat is antiseptic and is used in surgical dressing., Sphagnum or peat moss is also known as famine, food in China., The acidic nature of bog (where Sphagnum grows), helps in fossilization., Sphagnum contains sphagnal which is used in skin, diseases., It is a good absorbant hence also used as bandages., As biological material sex determination in, plants was discovered for the first time in, Sphaerocarpus.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŚĚŕĽęŐő坌ď–, , 47, , Chapter 9, , Pteridophyta, l, , l, l, , l, , l, , l, l, , Seedless vascular plants, also known as ferns and, fern allies, are a diverse group of plants consisting, of about 10,000 species., Pteridophyta claims a special position as the first, land plants., Pteridophytes are also called vascular cryptogams, as they possess xylem and phloem (vascular, tissues). Thus they are included as the first group, in tracheophyta., In pteridophytes, xylem lacks true vessels. In, phloem, companion cells and sieve tubes are, absent instead sieve cells are present., Pteridophytes are nicknamed as botanical snakes, as they evolved after bryophytes (botanical, amphibians)., During the carboniferous period, they were the, dominant land plant., Pteridophytes were the precursors to modern seed, bearing plants., , General characters, l, l, l, l, l, l, l, l, l, l, l, , Pteridophytes are mostly terrestrial., Grow well on moist shady localities., Salvinia, Azolla and Ceratopteris are true aquatic, ferns., Some species of Selaginella and Adiantum are, xerophytes., Marsilea occurs as a terrestrial, amphibious as well, as an aquatic plant., The main plant body is sporophytic., They are generally herbaceous, rarely climbers., The plant body is differentiated into true roots,, stem and leaves., The root system is of adventitious type., The roots possess a stele bound by endodermis, and pericycle., The stem may be aerial or rhizomatous., , l, l, l, , l, l, , l, l, l, , Vasculature of stem shows different type of stelar, organisation., The leaves are microphyllous or macrophyllous., Leaves may be scaly (Lycopodium, Equisetum) or, simple (Selaginella, Pleopeltis) or pinnate, (Pteridium, Dryopteris)., The leaves may possess ligule (Selaginella). They, may be sessile or petiolate., The leaves show chlorenchymatous mesophyll, which may be uniform in aquatic forms or may be, differentiated into palisade and spongy, parenchyma., The stomata are generally present on the abaxial, surface of the leaf., In Isoetes the plant body is distinguishable into a, corm like rhizomorph bearing roots and leaves., Secondary growth is absent in pteridophytes except, Isoetes., , Sporophyte, l, Meiospores are formed inside sporangia., l, Borne on leaves called sporophylls., l, On the basis of development the sporangia have, been classified by Goebel, (1881) into two, categories eusporangiate and leptosporangiate., l, Eusporangiate A large sporangium developing, from several initial cells producing many spores., These are sometimes fused to form synangia., l, Leptosporangiate Small, specialized sporangia, developing from a single initial cell producing a, small, definite number (< 128) of spores. These, often occur in a cluster (sorus) that is often covered, by a flap of tissue known as an indusium., l, Sometimes sporangia form compact cone like, structures bearing spores, called strobili, (Selaginella, Equisetum)., l, Sometimes sporangia are produced inside
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 48, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , specialised structures called sporocarps (eg, Marsilea, Salvinia, Azolla)., Most pteridophytes are homosporous (Lycopodium,, Equisetum), which means that they produce one, type of spore that contains both male and female, parts., A few pteridophytes are heterosporous, (Selaginella, Marsilea) which means they produce, distinct male and female spores., , Gametophyte, l, The gametophytes is called prothallus. The, prothalli may be monoecious or dioecious., l, Gametophyte is small or inconspicuous and is, usually independent and bear sex organs., l, The gametophyte are exosporic in homosporous, forms and endosporic in heterosporous form., l, Sex organs are multicellular and jacketed., l, Antheridia are completely embedded in the, prothallus while archegonia are partially, embedded., l, Archegonia consist of neck which usually project, from the surface prothallus., l, Archegonia contain 12 neck (14 in Lycopodium), canal cells. Venter is absent., l, Antheridia are generally sessile., l, The antheridia are having single layered jacket., l, Antherozoids are uninucleate, spirally coiled, biflagellate or multiflagellate structures (ferns)., l, Fertilization is affected by water medium. The, antherozoids are attracted towards the egg by a, chemotactic stimulus provided by the degeneration, of neck canal cells and venter canal cell in the form, of malic acid., l, The zygote (2n) formed after fertilization undergoes, divisions wholly (holoblastic) or partially, (meroblastic) to form embryo., l, The young sporophyte is dependent on the, gametophyte in earlier stages for food which is, drawn with the help of its foot., l, They show heteromorphic alternation of, generation., Stele, l, The conducting system of pteridophytes consists, of xylem and phloem and associated parenchyma, cells, all of which are organised into a stele (L., stela, rod or column) that is generally separated, from the outer cortex by a layer of endodermis., , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , On the basis of the kind of stelar organisation that, occur in different pteridophytes, an evolutionary, sequence can be recognised among different groups, of them., Protostele is the simplest, and considered to be, the most primitive type of stele. It consists of a, solid core of xylem surrounded by a cylinder of, phloem, enclosing no pith., All other types of steles have evolved from it in the, course of evolutionary specialisation. Protosteles, are most common in psilophytes and lycophytes,, but they occur also in the juvenile stems of ferns., Variation of the protostele include, the haplostele,, actinostele, plectostele, and mixedprotostele., Haplostele is protostele with central solid and, smooth core of xylem surrounded by phloem. This, particular type of protostele has been regarded as, the most primitive among the different types. It, occurred in primitive psilophytes like Rhynia, and, is found in a number of living genera, e.g., Selaginella kraussiana., Actinostele – In a number of pteridophytes, the, central xylem core of a protostele is not smooth but, is thrown into radiating ribs with the protoxylems, at the extremities and phloem alternating with its, rays, when seen in a cross section., Mixedprotostele – In Lycopodium cernuum, the, xylem when seen in a cross section, appears in the, form of irregular groups that are embedded in the, ground mass of phloem. This type of protostele is, called the mixedprotostele., A kind of stele in which there is present a pith in, the central region is called a siphonostele or, medullated protostele., This type of stele is thought to have been evolved, from a protostele by a degradation or reduction of, tracheary elements into parenchyma, and represents, a stage in evolutionary advance., In siphonostele, the vascular tissues are arranged, in the form of a hollow cylinder, with a distinct, pith in the centre. The siphonostele and its variations, are found frequently in the ferns., According to the distributional patterns of the xylem, and phloem, the siphonostele has been classified, into two types – ectophloic siphonostele,, amphiphloic siphonostele., In the ectophloic siphonostele, the phloem occurs, only on the outer surfaces of xylem cylinder. It is
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŚĚŕĽęŐő坌ď, , l, , l, , l, l, , l, , found in Equisetum and some ferns, like Osmunda, and Schizaea., In the amphiphloic siphonostele, the phloem, may b e both externa l a nd interna l. A n, amphiphloic siphonostele is also known as a, solenostele. It is found in the ferns, like Adiantum, and Marsilea., In its simples form, the siphonostele has no leaf, gaps, e.g., some species of Selaginella. A, siphonostele, which has no leaf gap is termed as, cladosiphonic siphonostele., A siphonostele with gaps caused by leaf traces is, termed phyllosiphonic siphonostele, e.g., Marsilea., Another modification of the siphonostele is seed in, the internode of Equisetum. Here, the vascular, system consists of collateral or bicollateral vascular, strands, that is, they have xylem on the inside and, phloem on the outside. Such arrangement is called, a eustele., In some ferns, e.g., Pteridium, a complex type of, stelar anatomy is seen in which there are two or, more concentric vascular systems that are, interconnected at intervals and usually all, contributing to the leaftraces. Such stele is said to, be polycyclic., , l, l, l, l, l, l, l, , l, l, , l, l, , Classification of pteridophytes, l, , There are 4 major types of pteridophytes –, psilopsida, lycopsida (club moss), sphenopsida, (horse tail), and filicopsida (ferns)., , Psilopsida, l, These are the most primitive and oldest known, land inhabiting plants, which are rootless., l, Presence of rhizoids borne over the rhizome., l, Aerial stems are often dichotomously branched,, green and photosynthetic., l, Leaf like enations may be present, leaf usually absent., l, Only stem contains vascular tissue – xylem and, phloem., l, Sporangia are terminal or axillary, spores produced, are homospores., l, Most of the plants include fossil genera – Rhynia,, Horneophyton;, l, Living representatives are only 2 – Psilotum and, Tmesipteris, both of them bear compound, sporangia or synangia., Lycopsida, l, Lycophytes are commonly referred to as club moss, , l, , l, l, l, , l, l, l, l, l, l, , l, l, , 49, , or ground pine, although they are neither moss, nor pine, e.g. Selaginella, Lycopodium., The plant body is a sporophyte which is, differentiated into root, stem and leaf., The leaves are microphyllous with spiral, whorled, or opposite phyllotaxy., The stele is a protostele. But sometimes, siphonostele or polystele may be present., Generally the sporophylls aggregate in the form of, cones or strobili., The sporophyll bear a single large sporangium on, the adaxial surface., The plants may be homosporous (lycopodium) or, heterosporous (Selaginella)., The gametophytes may be endosporic (within the, spore wall as in flowering plants) or exosporic, (spore germination with plant development outside, the spore)., Secondary growth absent except in Isoetes., In lycophytes, the gametophyte generation often, depend on fungus for survival, as they cannot, produce their own food., Selaginella show great variation in morphology as, prostrate, suberect, climbers, etc., Leaves may be dimorphic or uniform in shape and, size, presence of ligule and glossopodium (secretory, leaf base)., A leafless, colourless positive geotropic elongated, cylindrical structure growing downward from point, of bifurcation of stem is called rhizophore., Root is protostelic, monarch, with exarch xylem., In stem stele is diarch and exarch., In leaf stomata are present only on lower epidermis,, no differentiation of mesophyll tissues, chloroplasts, with pyrenoids., Vegetative reproduction is by fragmentation,, bulbils, tubers, or apogamy., The strobiles or spike bears both megasporophylls, (female) and microsporophylls (male)., Development of sporanguim is eusporangiate., The microspore consists of 1 prothalial, 8 jacket, cells and 4 primary androgonial cells., Antherozoids are spirally coiled and biflagellate., Archegonium consists of very short neck, single, neck canal cell, a venter having ventral canal cell, and an egg., Heteromorphic alternation of generation., Lycopsida includes both fossils and living forms.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŚĚŕĽęŐő坌ď–, l, l, l, l, l, , In leaves, both bicollateral or concentric and collateral, vascular bundles (in smaller Meres) are seen., In Dryopteris indusium is true, spores are monolete, and bilateral type and homosporous., Prothallus is protandrous (antheridia mature first), Venter lacks a covering or jacket., Psilotum is a primitive fern with no root system., Leaves are small and veinless., , l, , Table : Common names of some pteridophytes, Rootless pteridophyte, Xerophytic fern, Annogramma leptaphylla, Lycopodium, Selaginella, Selaginella rupestris, S. bryopteris, Adiantum, Dryopteris, , Salvinia, Woodsia elongata,, Drynaria, Adiontum, insicum, Smallest fern., Club moss, Spike moss, Bird’s nest moss, Sanjeevini, Walking fern, Male shield fern, , Economic importance, l, l, l, l, , l, , Several pteridophytes, particularly the species of, Lycopodium, Selaginella, Lygodium are ornamental., The plants of Selaginella are marketed as curiosities, in the name of resurrection plants., Lycopodium is used in skin diseases, a few others, species are used as kidney stimulant., Azolla is a water fern used as biofertilizer., , Evolutionary aspects of pteridophytes, l, , The pteridophytes (vascular cryptogams), resemble the bryophytes in the following, features –, –, Terrestrial habit., –, Like the bryophytes, they reproduce asexually, by means of spores. The spores are formed in, the same manner in both the groups., –, The sexorgans, the antheridia and archegonia, are essentially identical as regards to their, structure and ontogeny., –, In both the groups, the sexorgans have sterile, jackets around them., –, The male gametes, i.e., the sperms are ciliated., –, Fertilization takes place in the presence of, water., –, Encapsulation of embryo in the archegonium., –, Dependence of early embryo (sporophyte), upon the gametophyte., , l, , 51, , –, They exhibit regular alternation of generations., The pteridophytes differ from bryophytes in, the following features –, –, In the bryophytes, the gametophyte is the, dominant and conspicuous generation, the, diploid sporophyte being nothing more than, a sporebearing structure and is dependent on, the gametophyte for the nourishment. In the, pteridophytes, it is sporophyte rather than the, gametophyte which constitutes a large,, conspicuous and dominant phase in the life, cycle, while the gametophyte is always small, and inconspicuous., –, Plant body in pteridophytes shows, differentiation into true roots, stem and leaves., In bryophytes, there may be stems with leaves, but there are no roots., –, All the vegetative organs of the sporophyte of, pteridophyte possess vascular supply whereas, bryophytes do not possess vascular tissue., The pteridophytes resemble the seedbearing, plants (spermatophytes) in the following, features –, –, In both the groups, the sporophyte is the large,, conspicuous, freely existing, independent and, dominant phase in the life cycle. The, soprophytic plant body is differentiated into, true roots, stem and leaves., –, All the vegetative parts of the sporophyte have, typical xylem and phloem cells. The xylem, consists of tracheids of xylem parenchyma,, vessels being absent. Phloem consists of sieve, tubes and phloem parenchyma, the companion, cells being absent., Difference between pteridophytes and, spermatophytes –, –, Pteridophytes differ from the spermatophytes, in that they do not produce flowers, fruits or, seeds., –, In pteridophytes, excepting few cases, the, spores or gametophytes developed from them, are invariably liberated from the sporangia,, instead of being permanently retained within, them., –, In spermatophytes, water is not necessary for, fertilization., –, Steles are more advanced in spermatophytes, than those of pteridophytes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 52, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 10, , Gymnosperms, l, l, l, l, , l, , l, l, , Gymnosperms is derived from Greek words, Gymnos naked + sperma seed i.e., naked seed., Term gymnosperms was introduced by, Theophrastus., Goebel defined gymnosperms as “Phanerogams, without ovary”., Gymnosperms are the small group of plants which, constitute the subdivision of phanerogams or, spermatophyta., Age of higher gymnosperms is mesozoic era though, origin of order cycadofilicales of gymnosperms is, in late palaeozoic era., Gymnosperms are connecting link between, pteridophytes and angiosperms., Gymnosperms are placed in –, –, Archegoniate i.e., having archegonium as, female sex organ (bryophytes, pteridophytes,, gymnosperms)., –, Embryophyta Embryo is formed in life cycle, (bryophyta, pteridophyta, gymnosperms and, angiosperms)., –, Tracheophyta i.e. having vascular tissue or, xylem and phloem (pteridophytes,, gymnosperms and angiosperms)., The reason for the extinction of gymnosperms, may be the limited means of dispersal of seeds, (only by wind and man) and their failure to grow, under varied habitats (eg.water). Absence of, bisexuality provides lesser chances of self, fertilization and a good amount of pollen is wasted, during wind pollination., The numerical scarcity of present day, gymnosperms (14 genera and 51 species) in India, is due to the fact that they are the dwellers of, temperate regions and in India such climate exists, only in the Himalayas, and their adjoining hills., , l, l, l, , In the evolutionary point of view gymnosperms, are the most primitive seed plants., There are about 73 genera and 7000 species in, subdivision gymnospermae., Most of the genera are entirely extinct and only, a few are living., , General characters, l, l, l, l, , l, l, l, , l, l, , l, l, l, , Gymnosperms generally constitute dominant flora, of temperate region., Few gymnosperms, e.g.. Welwitschia are xerophyte., The gymnosperms are predominantly woody plants, represented by trees and shrubs. Few are climbers., Tallest gymnosperm is Sequoia sempervirens (about, 366 ft) and oldest gymnosperm is S. gigantea (about, 40005000 yrs). Smallest gymnosperm is Zamia, (25 cm)., Tap root system is present. It shows diarch to, polyarch nature., Stem are erect, branched and woody with leaf scars, and scale scars., Vascular bundles in stem are conjoint, collateral, and open. Secondary growth is present and annual, rings are formed., The xylem consist of xylem parenchyma and, tracheids with bordered pits., Vessels are absent in gymnosperms but present in, order – Gnetales (Gnetum, Welwitschia and Ephedra)., Therefore Gnetales are considered as connecting, link between gymnosperms and angiosperms., Due to the absence of vessels gymnosperm wood, is called soft wood., In phloem sieve cells and phloem parenchyma are, present but companion cells are totally absent., Leaves may be dimorphic or monomorphic and, show xerophytic characters like sunken stomata, and thick cuticle.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ťŇňŐřőĚŕŇř–, l, , l, , l, , l, , l, , l, l, l, , l, , l, l, , l, , l, l, l, , In gymnosperms, the reproductive structures are, mostly in the form of compact cones except female, organs of Cycas., Flowers are absent. There are two types of, s p orophylls – m icrosporophylls a n d, megasporophylls., The two types of sporophylls are usually aggregated, to form distinct cones or strobili : pollen cones, (male cones) and seed cones (female cones)., Seed do not occur inside a fruit due to absence of, ovary. They are naked or lie exposed on the surface, of megasporophylls., The megasporophylls bear ovules. The ovule is, generally orthotropous and unitegmic with three, layers (bigemic ovules are found in Gnetum and, Ephedra)., Endosperm is a prefertilization product and hence, haploid., Archegonium (female gametophyte) is with reduced, neck (with no neck canal cell)., Pollination is anemophilous (by wind) and the, fertilization is of siphonogamous type (occur by, pollen tube)., Polyembryony is the formation of more than one, embryo inside a single seed. It occurs in Pinus., Pinus ovule has 28 archegonia., Wood is manoxylic (soft and loose), eg. Cycas or, pycnoxylic (compact and hard), eg. Pinus., Fruit formation does not occur in the embryo of, gymnosperms, 2 or many cotyledons are present,, eg. 2 in Cycas and 10 11 in Pinus., Seed of gymnosperm represent three generation –, –, Parent sporophyte Represented by nucellus, and integument., –, Gametophyte Represented by endosperm., –, Future sporophyte Represented by embryo., Gametophyte generation is reduced and dependent, upon sporophyte generation., Alternation of generation is distinct., Development of oospore is meroblastic i.e., only, a part of zygote form embryo, eg. Pinus., , Classification of gymnosperms, l, , Gymnosperms are further classified into three, classes. (Sporne, 1965). They are cycadopsida,, coniferopsida and gnetopsida., , Cycadopsida, l, Cycadopsida is represented by small plants and, are comparatively primitive., , 53, , The stems are erect, unbranched and stumpy., The wood is manoxylic., l, Male cones are large and with compactly arranged, microsporophylls., l, The megasporophylls are loosely arranged and does, not form a cone. The megasporophyll bears large, ovule., l, The seeds are radially symmetrical. E.g., Cycas, (described in details), Microcycas, Zamia etc., Coniferopsida, l, Coniferopsida includes widely distributed larger, dominant gymnosperms on the earth at present., l, The plants possess profusely branched shoot system, which appears in the form of a cone., l, The leaves are simple and show many xerophytic, adaptations., l, The wood is pycnoxylic, pith is small., l, Sporophylls form cones. They are dioecious, hard, and woody., l, The seeds show bilateral symmetry, eg., Pinus, (described in details), Ginkgo, Taxus., l, Conifers are evergreen in the sense that they do not, shed their leaves as compared to deciduous plants which, become bare by leaf shedding in winter (autumn)., Gnetopsida, l, Gnetopsida includes advanced gymnosperms, represented by climbers, shrubs or small trees., l, The stems are branched., l, Leaves are broad, simple, ovate, or scaly., l, Secondary xylem shows vessels., l, Sexual structures are unisexual situated in, compound cones., l, Male sex organs are with perianth members and, the female sex organs shows single straight ovule., l, The ovules are of orthotropus type and show long, tubular micropyle., l, The embryo is with two cotyledons., l, The class Gnetopsida includes single order namely, Gnetales, eg. Gnetum., Table : Common name of some gymnosperms, Ginkgo biloba, –, Maiden hair tree, Sequoia, –, Red wood tree, Araucaria, –, Christmas tree/, Monkey’s puzzle, Cycas revoluta, –, Sago palm, Pinus gerardiana –, Chilgoza pine, P. roxburghii, –, Chir pine, P. insularis, –, Khasi pine, l, , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 54, , Ø, Ø, , Ø, , ŕďőĽę– ĐĽŐńŐĹť–, , Largest egg, sperm and ovule is found in, Cycas., The fertilization in Pinus is siphonogamous, i.e., by pollen tube. In ferns it is, zooidogamous i.e., by multiciliated sperm., In Cycas both the events occur at the same, time., Cycas revoluta and Gingko biloba considered, as living fossils. Ginkgo biloba is the single, living genus in a big fossilized order, Ginkgoales. Hence it is called living fossil., Cycas revoluta show the primitive characters, hence it is also considers as living fossil., , Economic importance, l, , l, , l, l, l, l, l, , l, l, , l, l, l, l, , Some of the gymnosperms like C. revoluta,, C. circinalis, Thuja, Taxus etc. are used for, ornamental purpose., Stem portion of C. revoluta, is a good source of, sago, a kind of starch used in making bread by, poor people mainly in Japan., Zamia is rich is starch and is used by many Indian, as food., Seeds and seed kernals of some species are roasted, and taken as food., Young succulent leaves of some species are used, as vegetables., Seeds and stem of C. revolula are used in making, wine in Japan., The leaves C. circinalis are medicinally very, important. The fresh juice extracted from the leaves, is used as medicine in stomach disorders, blood, vomitting and other skin diseases., Pollen grains of some Cycas plants are reported to, have some narcotic effect., Seeds and crushed bark of Cycas and its, megasporophylls when mixed with coconut oil are, used as poultice for sores and wounds in South, India., Thuja, Araucaria, Abies, Cryptomeria, Pinus, Taxus, are grown in parks., Seeds of P. gerardiana (Chilgoza), Ginkgo biloba,, Gnetum gnemon are edible., Manila copal an important varnish resin is obtained, from Agathis sp., Canada Balsam (Turpentine), a well known, turpentine is obtained from Abies balsamea (used, as mounting medium for biological preparation)., , l, l, l, l, , l, l, , l, l, , l, , Pinus marittima is a good source of bordeus, turpentine., Turpentine oil used in paint industries is mainly, obtained from resin of Pinus species., Timber is obtained from of Pinus, Abies, Cedrus,, Sequoia., Fossil resin (Amber) is obtained from extinct pine, Pinus succinifera, used in jewellery and carvel, object., Wood gas, wood tar and wood alcohol are obtained, from various species of Pinus. eg. Pinus sylnestris., Drug ephedrine is obtained from Ephedra which, is used in curing respiratory ailments including, asthma., A medicine of cancer called “taxol” is obtained, from the bark of Taxus., Gnetum ula is a common source of edible oil. It is, also used as massage in rheumatic pain. A volatile, oil extracted from the shoots and leaves of biota, (Thuja) is used as vermifuge. Oil of Juniperus is, medicinally important., Gnetum latifolium yields fibre used in making ropes, and nets., , CYCAS, Systematic position, –, –, –, –, –, –, , Phylum, Class, Subclass, Order, Family, Genus, , :, :, :, :, :, :, , Tracheophyta, Gymnospermae, Cycadophytae, Cycadales, Cycadaceae, Cycas., , External morphology, l, , l, , Cycas is an evergreen palmlike plant. It is the, only genus of family Cycadaceae represented in, India. Hence also called as living fossil., In India, four Cycas species are common in Orissa,, Bengal, Assam, Tamilnadu, Karnataka and, Andaman., Cycas revoluta, , :, , Cycas circinalis :, Cycas rumphii :, Cycas beddomei :, l, l, , Sago palm in India, Tesso, in Japan and China., Jangli madan mastkaphul., Kama, Paiyindu., –, , Dominant stage in Cycas is sporophyte., Plant body is differentiated into roots, stem and, leaves.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ťŇňŐřőĚŕŇř–, l, , l, , l, l, , l, l, l, l, , l, , l, l, , Type of root system in Cycas is tap root system., These roots are not green, positively geotropic, with no root hairs., From the lateral branches of the normal roots are, formed dichotomously branched, apogeotropic,, bluish green roots called coralloid roots., Rough texture of coralloid roots is due to the, presence of lenticels., Coralloid roots show symbiotic association with, bluegreen algae Anabaena cycadacearum, Nostoc, punctiformae., Young stem of Cycas is underground and tuber, like., Stem in Cycas is caudex, an unbranched columnar, stem, with a crown of leaves at the top., Leaves are of two kinds – scale leaves and foliage, leaves., A single scale leaf is a brown, dry, woody,, triangular structure, covered with brown hairs or, ramenta., Foliage leaves are unipinnately compound. Leaves, are leathery and thick, some leaflets at the base of, the rachis are reduced to spines., Leaves of Cycas are megaphylls (each leaflet, contains a single midvein)., Leaflets of young leaf show circinate vernation., , l, l, , l, , l, l, l, , l, , l, l, , l, , l, , l, l, l, l, l, l, , Internal structure of normal root of Cycas resembles, dicot root. Stele of normal root of Cycas is diarch/, tetrarch and exarch., Old coralloid root of Cycas consists of periderm, in the place of epidermis. Periderm is formed, from cork cambium., Cortex of coralloid root is divisible into – outer, cortex, middle cortex (algal zone) and inner, cortex., Tips of coralloid roots are degenerated due to, infection by bacteria., Some of the cells of outer and inner cortex contain, tannins, sphaeraphides and starch materials., Stele of coralloid root is triarch and exarch., Presence of girdle leaf traces is a characteristic, feature of Cycas stem., Mucilage canals (of schizogenous nature) are, present both in the cortex and the pith., Vascular bundles in young stem of Cycas are, conjoint, collateral, open and endarch., , Phloem is devoid of companion cells instead, albuminous cells are present in phloem., Anomalous secondary growth is present in Cycas, stem. Formation of more than one cambial ring, is an anomaly., Large amount of parenchymatous cells are present, with secondary xylem tracheids, so the wood is, called soft wood or manoxylic wood., Secondary xylem in Cycas is polyxylic (formation, of several rings of xylem)., In C. pectinata, 14 rings have been reported., Transfusion tissue (tracheid like and colourless), extends from the vascular bundle to the margin of, the leaflet., Rachis has epidermis with sunken stomata,, chlorenchyma, sclerenchyma, and ground tissue, with mucilage ducts., Vascular bundles in rachis of Cycas show inverted, omegashaped arrangement., Vascular bundle in rachis and leaflet is diploxylic, (presence of centripetal xylem and centrifugal, xylem is in the same vascular bundle) and, pseudomesarch., Xerophytic characters of Cycas leaflet, Leaflets are thick and leathery., Thick cuticle., Epidermis with thickwalled cells., Sclerenchymatous hypodermis., Presence of transfusion tissue., Absence of lateral veins., Hypostomatous condition, sunken stomata., , Anatomy, l, , 55, , Reproduction, l, l, l, l, , l, , l, l, , The Cycas plants reproduce both by vegetative and, sexual methods., Vegetative reproduction in Cycas takes place by, bulbils formed on stem., Cycas plant is dioecious i.e separate male and, female plants., Plant of Cycas is sporophyte (2n) and the sexual, reproduction is of oogamous type, i.e., takes place, by the fusion of distinct male and female gametes., The male and female gametes are formed by the, germination of micro and megaspores which are, borne on microsporophylls and megasporophyll., Microsporophylls unite to form a cone., Type of growth present in male plant of Cycas is
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 56, , l, l, l, l, , l, , l, l, l, l, , l, , l, l, l, , l, , l, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , sympodial. i.e.,the cone is later pushed to lateral, side and the stem continues to grow., The arrangement of microsporophylls on cone axis, of male cone is spiral., Each microsporophyll is 5 – 6 cm long, wedge, shaped woody structure., The terminal sterile part of microsporophyll is, called apophysis., Microsporangial sori are present on the abaxial, surface (under surface) of the microsporophyll, (fern character)., The number of microsporangia on a single, microsporophyll are 900 1000. In C. media there, are about 1160 sporangia., Microsporangia are shortly stalked, oval or oblong, structure and dehisce by longitudinal slits., Reduction division occurs in microspore mother, cells., Pollen grains are boat shaped., Female cone is absent as megasporophylls do not, aggregate instead are loosely arranged round, stem tip., Type of growth in female plant of Cycas is, monopodial. Megasporophylls of Cycas consist of, basal sterile stalk ovule bearing middle part and, upper sterile part or apophysis., Megasporophyll of Cycas is equivalent to the carpel, of angiosperms., Ovule of Cycas is naked, orthotropous and 2 – 12, reddish brown ovule borne laterally in two rows., The ovules of Cycas are largest in nature, can be, seen by naked eyes. In C. circinalis, the ovules are, largest in size i.e., about 6 cm in length and 4 cm, in diameter., The ovule consists of a micropylar beak, three, layered integument, a nucellus and female, gametophyte., Integument of Cycas is divisible into three layers–, outer fleshy layer (sarcotesta), middle stony layer, (sclerotesta) and inner fleshy layer., Number of vascular bundles that enter into the, ovule of Cycas is three., Female gametophyte in Cycas acts as endosperm, with 2 – 8 archegonia., Chromosomal condition of endosperm in Cycas is, haploid as it is formed before fertilization., A pollen chamber is present at the micropylar end, of nucellus., , l, l, l, , l, , Ripe ovule secretes pollination drop through the, micropyle, which trap pollen grain., Pollination in Cycas is anemophilous and direct., Pollen grains which are at 3celled stage (tube cell,, generative cell and prothalial cell) reach the pollen, chamber due to the drying of the pollination drop., A large pollination drop comes out of micropylar, end of ovule by disorganization of nucellar beak, (The apex of the nucellus develop beak like process., This is called nucellar beak)., Development of male gametes, Microspore, Prothallial cell Antheridial cell, Tube cell, , Generative cell, Stalk cell, , l, , l, l, l, l, , l, l, l, l, l, l, , Body cell, , 2 Sperms, The male gametes of Cycas are largest (300 m), in nature, visible to naked eye oval in form and are, multiciliate (multiflagellate)., Water is essential for fertilization in Cycas., Free nuclear divisions occur in the zygote of Cycas., Proembryo is formed first from the zygote., Proembryo is divided into 3 regions –, – Haustorial region for absorption of food, materials from the endosperm., – Suspensor region for pushing the embryo into, the endosperm., – Embryonal region that gives rise to proper, embryo., Embryo consists of suspensor, radicle, two, unequal cotyledons and plumule., Ovule is converted into seed having 3 layered seed, coat (outer, middle and inner)., Seed in Cycas is naked, endospermic and, perispermic., Type of germination in Cycas is hypogeal,, cotyledons remain underground., Alternation of generations is heteromorphic and, life cycle is diplohaplontic., The time gap between pollination and fertilization, is about 5 – 6 months., , PINUS, Systematic position, –, , Phylum, , :, , Tracheophyta
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ťŇňŐřőĚŕŇř, , l, , –, Class, :, –, Subclass :, –, Order, :, –, Family, :, –, Genus, :, Only six species are, Scientific name, , Gymnospermae, Coniferophytae, Coniferales, Pinaceae, Pinus., found in India., Common name, , Pinus gerardiana, Pinus wallichiana, P. roxburghii (P. longifolia), P. merkusii, P. insularis (P. khasya), P. armandi, l, , Chilgoza pine, Blue pine or kail, Chir pine, Teenasserim pine, Khasi pine, Armand’s pine, , In addition to above, some exotic species have, also been introduced in India, e.g., P. sylvestris,, P. laricia, P. montana and P. strobus (white pine)., , l, , l, l, , l, l, , l, , l, , l, , l, l, , l, l, l, , The plant body is sporophyte and the plants are, monoecious., The plant body is differentiated into roots, stem, and leaves., Pinus is an evergreen, perennial plant of, xerophytic nature. Mostly the species are tall and, straight., The whorled branching gives a typical conical or, excurrent appearance to the plant (due to apical, dominance)., Predominantly tap root system is present where, primary roots are less developed and lateral roots, are well developed., The root hairs are poorly developed and hence, ectotrophic mycorrhiza (symbiotic association of, fungal hyphae with the branches of roots) is of, common occurrence in Pinus for absorption of, water., The stem is tall, erect, cylindrical and the branching, is monopodial type., The stems are branched and the branches are, dimorphic (i) Branches of unlimited growth or, long shoots or long laterals and (ii) Branches of, limited growth or dwarf shoots or spur shoots, or short laterals., The dwarf shoots are borne on the axis of scale, leaves of long shoots., The leaves are also dimorphic, scaly and foliage., Scale leaves are green when young but at maturity, they become brown., , Foliage leaves are present only at the apex of dwarf, shoots. They are long, needlelike (acicular) green, structures, present for 3 or more years and thus the, plants are evergreen., The dwarf shoot with needles is called a ‘spur’., The number of needles per dwarf shoot is variable –, monofoliar (with one needle), bifoliar with two, needles), trifoliar (with four needles) and, pentafoliar (with five needles)., , Anatomy, l, l, l, l, l, , External morphology, l, , 57, , l, l, l, l, , l, , l, , l, , l, l, l, l, l, l, , The primary root is distinguishable into epidermis,, cortex, endodermis, stele and pith., Pericycle is multilayered., The cortex is infected with ectotrophic mycorrhiza., Vascular bundles are radial., The xylem is Yshaped in T.S. being forked at the, protoxylem end., There is a resin canal in the fork of xylem., The xylem is made up of tracheids only, vessels, are absents., The phloem is made up of sieve cells but there are, no companion cells., In young roots, cambium is absent but at maturity, below the phloem patches, arches of cambium, are formed. It cuts off secondary xylem on the, inner side and secondary phloem on the outer, side., In a T.S. the young stem of Pinus appears to be a, ribbed structure due to the presence of leaf bases, and dwarf shoots., Epidermis of stem is provided with thick cuticle, and hypodermis is sclerenchymatous, resin canal, is present in cortex, some cells contain tannins., The vasculature of stem comprises a eustele and, vascular bundles are conjoint, collateral and open, bundles resembles dicot stem. It is described as an, eustele., Xylem is endarch devoid of vessels after secondary, growth and form nonporous wood., Protoxylem consists of annular and spiral trachieds,, metaxylem has uniseriate bordered pits on tracheids., Presence of bars of sanio., The wood is pycnoxylic (compact and hard). Phloem, is made up of sieve cells and albuminous cells., The albuminous cells are analogus to companion, cells of angiosperms but not homologous., Intrafascicular cambium is present in between
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 58, , l, , l, l, , l, l, l, , l, l, l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , xylem and phloem, presence of parenchymatous, medullary rays., Secondary growth is observed consisting of distinct, annual ring containing spring wood and autumn, wood., Autumn wood is formed during autumn and cells, are smaller squarish and thick., Spring wood is formed during spring and cells are, thinner, larger and polygonal. This is called, pycnoxylic., Resin canals are present in cortex and xylem and, are schizogenous cavities., Needles have sunken stomata throughout the surface, i.e., amphistomatic., The stomata comprises of two guard cells, surrounded by 68 subsidiary cells. The subsidiary, cells enclose a supra stomatal space called as, vestibule., Mesophyll is undifferentiated into palisade and, spongy parenchyma., Vascular bundles are obliquely placed, collateral,, open, endarch., Vascular cylinders were surrounded by single, layered endodermis having barrelshaped cells with, casparian strips., Pericycle is multilayered and composed of four, types of cells parenchymatous cells,, sclerenchymatous cell, albuminous cells,, tracheidal cells., Transfusion tissue is composed of 2 types of cells, tracheidal cells and albuminous cells., Tracheidal cells are tracheidlike cells having, pits, found close to the xylem elements of the, bu nd les. This is g enera lly referred to as, transfusion tissue., Albuminous cells are living cells without pits and, help conduction., Xerophytic characters shown by Pinus are –, (i) reduced leaf surface (acicular), (ii) presence of, thick cuticle, (iii) thick walled hypodermis, (iv), presence of sunken stomata, (v) special type of, mesophyll (arm palisade), (vi) sclerenchymatous, sheath inbetween the bundles., , l, l, , l, , l, , l, , l, l, , l, , l, , l, l, l, , l, l, l, , Reproduction, l, l, , Vegetative reproduction is absent in Pinus., Pinus is a heterosporous, monoecious plant, , l, , producing micro and megaspores in micro and, megasporangia respectively., The microsporangia are borne on microsporophyll, which constitutes the male cone., A male cone consists of a central axis bearing 60, 135 microsporophylls in spiral manner. It is,, therefore, comparable to male flower of, angiosperms., Each microsporophyll is small, brown, scaly and, triangular having a short stalk and leaflike sterile, expansion called apophysis., Microspores are produced in such a large number, that at the time of their dispersal, yellow clouds of, pollen grains are produced, which is called “shower, of sulphur” or “shower of golden dust”., The megasporangia are produced on ovuliferous, scales formed along with a bract. The ovuliferous, scales and bracts constitute the female cone., Each female cone matures in three years. In the, third year it matures with ovules., Each female cone is an oval or somewhat elongated, structures with an elongated central axis around, which a large number of megasporophylls are, arranged in an acropetal and spiral manner., The female cone represents an inflorescence, because the ovule bearing ovuliferous scales are, borne on the bract scales which are directly formed, on the central axis., A megasporangium or ovule of Pinus is, orthotropous. Ovule has an oblique micropyle,, nucellus and female gametophyte having 1 – 8, archegonia., Archegonia has 2 – 4 celled neck, ventral canal cell, and egg., The ventral canal cell disorganizes before, fertilization. Neck canal cells are absent., Integument is differentiated into 3 layers : outer, fleshy layer, middle fleshy layer, inner fleshy, layer., The pollination in Pinus is anemophilous (brought, out by wind)., There is a long interval of about a year between, pollination and fertilization., Endosperm of Pinus differs from angiosperms as, it is a prefertilization structure, while in, angiosperms it is a postfertilization structure., The micropyle of each ovule contains mucilage or, pollen drop to catch pollen grains.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ťŇňŐřőĚŕŇř, Pollen grain, 2 prothalial cell, , generative cell, stalk cell, , l, , tube cell, , body cell pollen tube, male gametes, (non flagellate), , l, , l, l, l, , l, , l, , The zygotic nuclei divide to form four nuclei., These four cells divide simultaneouly thrice to form, four tiers of four cells each., Embryonal tier (4 cells) is the lowermost tier,, which forms the embryo., Suspensor tier (4 cells) : Above the lower tier, which elongates and gives rise to long suspensors., Rossette tier (4 cells) : Above the suspensor tier, and mediates between the suspensor tier and, nutritive tier., Nutritive tier (4 cells) : The cells remain open, above and provide nutrition to the remaining, proembryo., Since only a part of the oospore is involved in, the formation of the embryo, the development is, said to be meroblastic., , l, , l, l, , l, l, l, , l, , 59, , All the four cells of the embryonal tier separate, from each other and develop independently into, four embryos. The formation of more than one, embryos from one oospore is called cleavage, polyembryony., Simple polyembryony is also found in Pinus, (where more than one embryos are formed as a, result of fertilization of different archegonia)., Inspite of having polyembryony only one embryo, is found at maturity., The mature embryo consist of 9 – 14 cotyledons,, plumule (embryonic shoot) and radicle (embryonic, root)., The mature ovule with embryo constitutes seed., As the seed of Pinus is winged it is anemochorous, (dispersed by wind)., These seeds show three generation , –, Old sporophytic generation by testa, tegmen, and nucellus., –, Gametophytic generation by endosperm., –, Future sporophytic generation by embryo., The germination of seed is of epigeal type, e.g.,, the cotyledons come above the ground by the, elongation of hypocotyl.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 60, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 11, , Angiosperms, l, , l, l, , l, l, l, , l, , l, l, , l, , l, , Angiosperms or flowering plants form the largest, group of plant kingdom, including about 300, families, 8000 genera and 300,000 species., They are considered to be highest evolved plants, on the surface of earth., Angiosperms better known as flowering plants,, are vascular seed plants that produce flowers and, fruits., They are by far the most diverse and, geographically widespread of all plants., There are about 250,000 known species of, angiosperms., As late as the 1990s, most plant taxonomists divided, the angiosperms into two main classes – the, monocots and dicots., A typical angiospermic plant is sporophytic (2n), and have both vegetative parts and reproductive, parts., Vegetative parts or organs of an angiospermic, plant are root, stem and leaves., Roots collectively constitute root system, which, generally constitute the under ground portion of, the plant., The stem with its branches and leaves constitute, shoot system, which is generally above ground or, aerial part of the plant., Flower formation is the transitional phase (change, from vegetative phase to reproductive phase) in the, life cycle of an angiospermic plant., , l, l, , l, , l, l, , l, , l, , l, , Forms of angiosperms, l, , l, , l, , On the basis of habit an angiosperm plant can be, a herb, shrub, tree creepers, twiners, climber and, lianas., Herbs are small plants with soft and pliable stems., Herbs can be annual (e.g., Buttercup), biennial, (e.g., Henbane) and perennial (e.g., Canna)., Shrubs are woody plants and are branched near, , l, , l, , the ground, stem is not much developed into clear, trunk., Trees are woody plants, which are branched at some, height and thus have much developed trunk., Trees further may be excurrent or conical (having, basal thicker portion and thinner or tapering, portion above), caudex (unbranched stem with, crown of leaves at apex) or deliquescent/, decurrent (sub branches grow after death of apical, bud of stem)., Trailers are plants which spread on the ground, without rooting at intervals, e.g., Tribulus terrestris,, Euphorbia prostrata., Creepers are plants spread on the ground, rooting, at intervals, e.g., strawberry., Twiners are weakstemmed plants where the stem, coils or twines around an upright support, e.g.,, Ipomoea cairica (Railway creeper), Quisqualis, (Rangoon creeper)., Climbers are plants that climb up an upright support, by special clinging or clasping structures like, tendrils, roots and hooks., Woody twiners and climbers are called lianas. They, are found in tropical evergreen forests, e.g., Phanera, (= Bauhinia) vahlii, Hiptage., Epiphytes are plants which live on other plants for, space only. Angiospermic epiphytes commonly live, on trees, e.g., Vanda, Dendrobium. They often, possess hanging roots with hygroscopic outer, spongy tissue called velamen., Culms are the plants where stem is having very, clear nodes and internodes (joined stem). Here, nodes are solid and internodes are generally hollow,, e.g., grasses (members of gramineae) and sedges, (members of cypreceae)., On the basis of life span angiosperm plants can be, annual, biennials or perennials.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĹĽŐřőĚŕŇř–, l, l, , l, , l, l, , l, l, l, l, , l, , l, , l, , l, , Annual plants complete their life cycle within, one year, eg. rice, wheat., Such annuals which complete their life within a, brief or short (generally 46 weeks) period of time,, are called ephemeral annuals or ephemerals, e.g.,, Argemone (pili katili), Artemisia, Astragalus, etc., Biennials complete their life cycle in two growing, seasons (i.e., complete their vegetative phase in, first season and reproductive phase in second, season). Eg Henbane, raddish., Perennial grow for a number of seasons or for, many years., Perennial plants may be polycarpic i.e., produce, flower and fruit every year, eg. mango or, monocarpic i.e., produce flower and fruit once in, life, e.g., Bambusa bamboos., The century plants flowers after about 100 years, and after flowering dies., Banana (Musa) is one of the largest perennial herbs., On the basis of mode of nutrition angiosperms, may be autotrophic or heterotrophic., Plants which can manufacture their own organic, food from inorganic substances, are called, autotrophic or autophytes., Photoautotrophs or photoautotrophic plants, manufacture their food in presence of chlorophyll, and light from CO2 and H2O by the process of, photosynthesis, e.g., most of the green plants., Chemautotrophs or chemosynthetic plants, manufacture their food using chemical energy (not, light energy) without presence of chlorophyll, e.g.,, chemosynthetic bacteria., The plants which are unable to manufacture their, own food and depend upon other green plants for, food are called heterotrophic or heterotrophs., Hetrotrophic plants are of three types –, –, Saprophytes – obtain nourishment from dead, decaying organic matter, –, Parasites – obtain nourishment from other, living organisms, –, Carnivorous – predator plants that grow in, nitrogen deficient soil., , l, l, l, l, l, l, l, l, , l, , l, l, l, l, l, l, l, l, l, l, , l, l, , Vegetative and floral characters of angiosperms, l, l, , Roots are adventitious in monocots and tap root, in dicots., Stems may be erect, branched or unbranched,, trailers or climbers or twiners., , l, l, l, , 61, , Leaves varies like seed leaves, scale leaves, bract, leaves, floral leaves, prophylls, foliage leaves., Leaves may be simple or compound, lamina may, be dorsiventral or isobilateral., Foliage leaves are green, expanded, dorsiventrally, flattened with or without stipule., Leaf base in monocots are generally sheathing, without stipules., Flowers may be single or in groups forming, inflorescence., Inflorescence may be racemose or cymose or, special type., Flowers may be complete, incomplete, unisexual,, bisexual, sterile or naked., Complete flower have all the four whorls – calyx,, corolla, androecium and gynoecium while, incomplete flower have one or more of the four, whorl missing., Bisexual flower have both androecium and, gynoecium while unisexual plant have either, female part (pistillate) or male part (staminate)., Essential whorls of flowers are stamens and, carpels., Stamens consist of filament, connective and, anther., Carpels consist of ovary, style and stigma., Pollen grains are formed within anther., Ovules are present within ovary., The development of male gametophyte is completed, within the pollen tube before fertilization., Double fertilization occurs and endosperm is, triploid., Seeds always remain within fruit., Angiosperm seeds may have one, two or many, cotyledons., A fruit is a mature ovary as seed develop from, ovules after fertilization, the wall of the ovary, thickens to form the fruit., Fruits protect dormant seeds and aid in their, dispersal., Fruits are classified into several types depending, on their developmental origin as – simple fruits, (derived from a single ovary), an aggregate fruit, (results from a single flower with several carpels),, a multiple fruit (develops from an inflorescence)., Seeds may be endospermic or nonendospermic., Germination of seeds may be epigeal or hypogeal., Vascular bundles of root are radial and exarch in, angiosperm.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 62, , ŕďőĽę– ĐĽŐńŐĹť–, , Number of vascular bundles in root anatomy are, more than six in monocots and 26 in dicots., In stem vascular bundles are conjoint, collateral, or bicollateral open (in dicot) or closed (in, monocots) and endarch., Ground tissues are not differentiated into cortex,, endodermis, pericycle and pith in monocots stem, while separated in dicots., Pith is large in roots of monocots while absent or, very small in dicot., Secondary growth occur in dicot stem but not in, monocot stem., Refinements in vascular tissue, especially xylem,, probably played a role in the enormous success of, angiosperms in diverse terrestrial habitats., Like gymnosperms, angiosperms have long, tapered, tracheids that function for support and water, transport., Angiosperms also have fibres cells, specialized for, support, and vessel elements (in most angiosperms), that develop into xylem vessels for efficient uptake, of water. While evolutionary refinements of the, vascular system contributed to the success of, angiosperms, the reproductive adaptations, associated with flowers and fruits contributed, the most., One hypothesis for the function of double fertilization, is that it synchronizes the development of food, storage in the seed with development of the embryo., Double fertilization may prevent flowers from, squandering nutrients on infertile ovules., , l, l, , l, , l, l, l, , l, , l, , l, , Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, , Economic importance of angiosperms, l, , l, , l, l, , l, , l, , l, , Agriculture is almost entirely dependent on, angiosperms, either directly or indirectly through, livestock feed., Of all the families of flowering plants, the Poaceae,, or grass family, is by far the most important, providing, the bulk of all feedstocks (rice, corn maize, wheat,, barley, rye, oats, millet, sugar cane, sorghum)., The fabaceae, of legume family, is in second place., Also of high importance are the Solanaceae, or, nightshade family (potatoes, tomatoes, and pepper,, among others), the Cucurbitaceae, or gourd family, (also including pumpkins and melons), the, Brassicaceae, or mustard plant family (including, rapeseed and cabbage), and the Apiaceae, or parsley, family., Many of our fruits come from the Rutaceae, or rue, family, and the Rosaceae (rose family, including, apples, pears, cherries, appricots, plums, etc)., In some parts of the world, certain single species, assume great importance because of their variety, of uses. An example is the coconut (Cocos nucifera), on Pacific atolls. Another example is the olive (Olea, europaea) in the Mediterranean., Flowering plants also provide economic resources, in the form of wood, paper, fibre (cotton, flax and, hemp, among others), medicines (Digitalis,, camphor), decorative and landscaping plants, and, many other uses., [For more details on economic importance, refer, chapter Economic Botany.], , The oldest angiosperm fossils are found in rocks in the early cretaceous, about 130 million years ago., By the end of the cretaceous period, 65 million years ago, angiosperms had become the dominant plants, on Earth., Scindapsus officinale (family, araceae) is exceptional angiosperm which begins terrestrial life but at, maturity becomes epiphytic., Angiosperms with haustoria are parasitic form as Viscum, Loranthus and Cuscuta etc., Smallest angiosperm is duckweed (Lemna)., Smallest flower belongs to Wolffia microscopia., Largest flower belongs to Rafflesia arnoldi (1 m in diameter weigh, 15 kg) a fatal root parasite., Smallest parasitic angiosperm is Arceuthobium minutissimum., Leafless inflorescence is depicted by Balanophora dioica., Largest inflorescence of the world belongs to Puya raimondii (32 ft.) and the second largest is, Amorphophallus (8 ft)., Monotrapa and Sarcodes (family pyrolaceae) are total saprophytic angiosperms having mycorrhizae., Dicot without cotyledons is Cuscuta reflexa.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŢŐńśŚĽŐňďŕť– ŚŕĚňęř– ·– ►ńďřřĽěĽĘŐň– Őě– ○ňĽŇďńř–, , 63, , Chapter 12, , Evolutionary Trends &, Classification of Animals, l, l, , l, , l, , l, , l, l, , l, , l, l, , l, , All the present day animals species have originated, more than one billion years of evolution., Aristotle (father of biology) divided animal, kingdom into enaimia (vertebrates having red, blood) and anaimia (vertebrates with no red blood)., Animal kingdom is the kingdom of multicellular, eukaryotic animals and is one of the five kingdom, scheme of classification (by Whittaker)., Since biospheres contains enormous diversity of, animals so their classification is based on, different important characteristic features like , habitat, germ layers, coelom, grade of organization,, symmetry etc., Animals have their own habitat such as land,, (terrestrial animals), water (aquatic animals) and, air., Types of aquatic animals are – zooplankton,, nekton and benthon., Zooplankton are passively floating or drifting, animals in a body of water. Eg. many protozoans,, protists, small crustaceans and various invertebrates, larva., Nekton are actively swimming aquatic organisms, in a body of water, able to move independently of, water currents, eg. shark, bony fishes., Benthon living at bottom. It may be sedentary, or motile, eg. starfish, sea cucumber, sponges etc., Both zooplankton and nekton are called pelagic, animals because they live in open water of a sea, or lake., Types of terrestrial animals are, –, Cursorial–Run fast (Kangaroo, dog, horse), –, Fossorial–Live in burrows/underground, (Earthworm, rabbit), , Arboreal–Live on trees (Bats, monkeys), Scansorial–Climb walls, rocks etc. (Wall, lizard, flying squirrel), –, Aerial/flying–Can fly (Winged insects, birds,, bats etc.), According to habit animals may be–, –, Solitary (live alone)–Tapeworm, grasshopper., –, Colonial (live in groups and help one another,, shows social life)–Honey bees, termites,, wasps, ants., –, Gregarious (live in groups, but can’t help)–, Horse, dog., –, Parasites (depend on other animals for food,, protection etc)–Tapeworm, Ascaris etc., –, Motile–Earthworm, cockroach etc., –, Mimicry (Resemblance of another animal for, the purpose of concealment, protection or, some other advantage)., Three basic types of body plan in animals are–, cell aggregate, blindsac and tube – with in a, tube plan., In cell aggregate body plan an animal can exhibit, cell aggregates with no tissue or organs and exhibit, loosely arranged cells, eg. porifers., Blind sac plan or hollows sac plan have a single, opening for digestion and egestion in their digestive, tube (bind sac), eg. cnidarians and platyhelminthes., Tube – with in a tube plan have a complete, digestive tract (with mouth and anus) forming a, internal tube. e.g., annelids, arthropoda, molluscs,, echinodermata and higher chordates., In protostomatic forms mouth is formed from, blastopore region and appears first in the embryo,, eg. annelids, aschelminthes, arthropods and, molluscs., –, –, , l, , l, , l, , l, , l, , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 64, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Some terms of animal bodies., Term, , Description, , Oral, , The end towards mouth, , Aboral, , The end opposite to mouth, , Anterior, , The head end, , Posterior, , The tail end, , Cephalic, , Toward the head, , Caudal, , Toward the tail, , Proximal, , Toward the point of attachment of a, structure on the body, , Distal, , Away from the point of attachment of a, structure on the body, , Dorsal, , The back of an animal, usually the upper, surface, , Ventral, , The belly of an animal, usually the lower, surface, , Superior, , Above a point of reference, , Inferior, , Below a point of reference, , Pectoral, , The chest region– the area supported, by fore limbs, , Pelvic, , The hip region– the area supported by, hind limbs, , l, , l, , l, , l, , l, , l, l, l, , In deuterostomatic forms anus develops from, blastopore region and appears first in the embryo,, eg. echinoderms and chordates., Protostomes and deuterostomes also differ in the, mode of coelom formation, early development, like cleavage and type of embryo., Metamerism is body structure having repeated, segments. It help develops specialization of, organs. eg., annelids., False segmentation or pseudometamerism occur, through budding in tapeworm. In them body is, divided into many segments known as proglottids., Metamerism results in the separation of, mesoderm into segmented blocks of muscles. In, annelids, there are both external and internal, segmentation., Arthropods shows only external segmentation., In chordates only internal segmentation is, present., Symmetry refers to the similarity to the, arrangement of parts on the opposite sides of the, , l, l, , l, , l, l, , l, l, l, , l, , l, , l, , l, , l, l, , body which make possibility to cut the body into, two similar halves by one or more planes., Types of symmetry are – spherical, radial and, bilateral., Spherical symmetry divides the body into, similar halves by any plane passing through the, centre. In this the sides of the body are, indistinguishable., Spherical symmetry is found chiefly among some, of the protozoa (e.g., Volvox, heliozoa, radiolaria), and is rare in animals., Spherical forms are best suited for floating and, rolling., In radial symmetry, body can be divided into equal, halves by any plane passing through the centre, from top to bottom. This symmetry permits an, animal to detect food or danger approaching from, any side, eg., Hydra and jellyfish., Radial animals are usually sessile, freely floating, or weakly swimming., The animals, with no front or back end, can interact, with their environment in all directions., The echinoderms (sea stars and their kin) are, primarily bilateral animals (their larvae are bilateral), that have become secondarily radial as adults., In biradial symmetry the body can be cut into, two similar halves by one or two vertical planes, only, eg., Sea anemones and sea walnuts., The main distinguishing feature between radial, and biradial symmetry is oral (which bears, mouth) and aboral side (which is opposite to the, mouth)., In all vertebrates & most invertebrates the chief, organs of the body are paired and are arranged on, the sides of a central axis connecting the head, with the tail. With the result, the body can be divided, into two similar halves by a single plane. Such a, symmetry is called bilateral symmetry., Bilateral symmetry allows an animals to have, more streamlined shape and to concentrate the, power of its muscles and appendages for producing, motion in one direction. In this the sides, surfaces, & ends of body are clearly distinguishable., Bilateral symmetry developed due to, cephalization., Cephalization means definite head at anterior end., It involves the concentration of nervous tissues, (brain) & sense organs in the head.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŢŐńśŚĽŐňďŕť– ŚŕĚňęř– ·– ►ńďřřĽěĽĘŐň– Őě– ○ňĽŇďńř–, l, , l, l, , l, l, , l, l, , l, , l, , l, , l, , l, , This arrangement is an assest in an adjustment, with the environment as the anterior end of a moving, animal is the first to encounter changes in the area, it is entering. It evolved in the remote past due to, creeping habit., Cephalization begins in platyhelminthes., Coelom is the name given to the internal body, cavity that separates the digestive tract from the, outer body wall., It is filled with a fluid and lined by peritoneum, derived from mesoderm., Function of body cavity are–, –, Cushion the organs thus preventing injury., –, Allow internal organs to grow and move, independently of the outer body wall., –, Serve as a hydrostatic skeleton in soft bodies, coelomates such as earthworms., Types of coelom are – acoelom, pseudocoelom, and eucoelom., Acoelom means without body cavity which is due, to failure of mesoderm to cavitate during, embryogeny, so no coelom, no peritoneum. The, area between the digestive tract & outer wall is, filled with cells, producing a solid body, eg. porifera,, coelenterata, platyhelminthes (flatworms)., Pseudocoelom or false body cavity means presence, of coelom (that develops from the blastocoel) but, not lined by mesoderm, eg. roundworms, (nematodes), rotifers., Eucoelom or true coelom i.e., lined by mesoderm,, resulting in tubewithintube design, eg. higher, invertebrates (annelids, echinoderms) and chordate., True coelom is of two types :, –, Schizocoelom (develop as a split in the, mesoderm sheet), eg. – annelida, arthropod &, molluscs., –, Enterocoelom (mesoderm arises from the wall, of embryonic gut or enteron as hollow, outgrowths or enterocoelomic pouches),, eg.– echinoderms & chordates., In arthropoda and molluscs the actual or true, coelom is reduced but spaces between viscera grow, and form a large cavity filled with blood called, haemocoel (= haemocoelom)., Appendages are projecting parts of body used for, specific functions like feeding, locomotion and, sensation, eg. tentacles, setae, parapodia, antennae,, , l, l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, , l, , l, , 65, , legs, wings, fins etc., Skeleton of animals provide shape, support,, protection and help in locomotion., Exoskeleton is secreted by skin or ectoderm and, made of non living materials, eg. calcarious shell, of molluscs, chitinous cuticle of arthropods, hair,, nail, scale, hoofs, horns, feathers., Endoskeleton is internal skeleton which is, produced by mesoderm or occasionally endoderm,, eg. notochord, cranium, skeleton and cartilaginous, tissue from most of the vertebrates., Endoskeleton consists of cartilages, bones and, connective tissues of various types., Level of organisation are of five types – acellular,, cellular, tissue, organ and organ system., All activities at protoplasmic grade (or acellular), level are confined within the limits of a single, plasma membrane (plasmalemma), eg. protozoa., In cellular grade body consists of many cells., They exhibit division of labour for performing, specialized functions., Cellular level of organization are of two types–, cellular colony level of organisation where all, the cells are similar and found in protists and some, algae (Volvox), and cellular aggregate level of, organisation, found in sponges where the cells, are of different types but are not organised into, tissues., In celltissue grade cells are not only specialized, for different function but also certain similar cells, gather together to form tissues as well. A noteworthy, example is the nerve net formed by nerve cells &, their processes, eg. coelenterate., Tissue organ grade (or organ level) appears in, flatworms with the arrangement of tissues to form, organs., In organ system grade body is multicellular with, tissues, organs & system. In this, organs join, together in a system to perform some functions. It, is typical to all higher invertebrates forms., A multicellular body shows organisation into:, tissues ® organs ® organs system, eg. round worms, to chordates., A digestive tract is present in all those animals, which show tissue and higher level organisation is, called enterozoa., Digestive tract may be incomplete with single, opening both for ingestion as well as elimination,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 66, , ŕďőĽę– ĐĽŐńŐĹť, , eg. coelenterate and earthworm; and complete with, two openings one for ingestion and another for, elimination, eg. from roundworm to mammals., In many animals the body temperature varies, according to surrounding environment for normal, vital activities. They are poikilothermic &, homoiothermic., Cold blooded animals (or poikilothermic animals),, often known as ectotherms, do not keep their body, temperature constant so when their body temperature, is high (on a hot summer day), they can be very, active & when it is low (on a cold winter night) they, can produce energy only slowly & so are torpid, (means very inactive & can move slowly). Eg., invertebrates, fish, amphibians & reptiles., , l, , l, , l, , l, l, , l, , Warmblooded animals (or Homoiothermic, animals) often known as endotherms, have, relatively constant body temperature., Their body temperature is independent of that, of their external environment., Body temperature of endotherms is derived from, heat produced by their own oxidative metabolism, & the presence of insulating hair, feathers &, blubbers prevents this internally generated heat, from freely diffusing to the external environment., Eg. mammals & birds., When both male & female sex organs are found in, one individual. Then the individual is called, hermaphrodite (bisexual or monoecious),, eg. earthworm, liver fluke, leech etc., , Table : Modes of respiration., Mode of respiration, , Respiratory organ, , Examples, , 1., , Bodysurface respiration, , Bodysurface, , Sponges (Leucosolenia) and coelen, terates (Hydra), , 2., , Branchial respiration, , Gills, , Crustaceans (Prawn), cartilage and, bony fishes., , 3., , Cutaneous respiration, , Skin, , Annelids (earthworm) and, amphibians (frog), , 4., , Tracheal respiration, , Tracheae (ectodermal tubes), , Insects (cockroach), centipedes,, millipedes., , 5., , Pulmonary respiration, , Lungs, , Most of tetrapods., , 6., , Booklung respiration, , Booklungs, , Arachnids (spiders and scorpions)., , 7., , Bookgill respiration, , Bookgills, , Limulus (Kingcrab), , Table : Types of excretory organ., Animal groups, , Excretory organs, , 1., , Porifera and Coelenterata, , By diffusion through body surface, , 2., , Platyhelminthes (Flatworms), , Protonephridia (flame cells), , 3., , Aschelminthes (Round worms), , Excretory canals (Renette cell), , 4., , Annelids (Segmented worms), , Nephridia, , 5., , Crustaceans (e.g. Prawn), , Antennary or green glands, , 6., , Arachnids (e.g., Scorpion), , Coxal glands and Malpighian tubules (in some spiders), , 7., , Insects, centipedes and millipedes, , Malpighian tubules and urate cells, , 8., , Molluscs, , Renal organ or renal sac, , 9., , Vertebrates, , Kidneys
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŢŐńśŚĽŐňďŕť– ŚŕĚňęř– ·– ►ńďřřĽěĽĘŐň– Őě– ○ňĽŇďńř–, , 67, , Table : Types of nervous system in different animal groups., Animal group, , l, , l, , l, l, l, l, l, l, , l, , Type of nervous system, , 1., , Coelenterates, , Diffuse type (nerve fibres not differentiated into dendrons and, axon)., , 2., , Flatworms and roundworms, , Ladder type (formed of a nerve ring and many nerve cords which, are interconnected by connectives)., , 3., , Annelids, , Central nervous system (CNS) formed of a circumpharyngeal, nerve ring and ventral solid and ganglionated nerve cord., , 4., , Arthropods, , CNS formed of a circumoesophageal nerve ring and a double,, ventral, solid and ganglionated nerve cord., , 5., , Molluscs, , Formed of a few ganglia interconnected by some commissures and, connectives., , 6., , Echinoderms, , Two nerve rings (oral and aboral) and radial nerves., , 7., , Vertebrates, , CNS formed of anterior broader brain and posterior longer and, narrow spinal cord. CNS is dorsal, hollow and nonganglionated., , Unisexual (dioecious) have only one type of sex, organ (either male or female), eg frog, lizard, bird,, rabbit., In sexual dimorphism male and female can be, distinguished externally, eg. peacock, peahen, lion, & lioness & human beings., In protandry testes mature earlier than ovary,, eg. earthworm., In protogyny ovaries mature earlier than testes,, eg. Amphioxus., Internal fertilization takes place in the genital, tract of the female, eg. reptiles, birds and mammals., External fertilization occurs outside the body of, female, eg. starfish, frog., Self fertilization involves fusion of the gametes, of same parent, eg. tapeworm., Cross fertilization occurs when the gametes are, from different parents, eg. earthworm, all fishes,, amphibians, reptiles, birds & mammals., On the basis of site of development of zygote,, animals may be –, –, Oviparous–Egg laying animals, eg. frog,, reptiles, birds & mammals (prototheria), –, Viviparous–Fertilization & development, internal & nourishment obtained through, mother (through placenta), eg. mammals., –, Ovoviviparous–Fertilization & development, internal but no placenta formation, eg. shark,, , l, , l, , l, , l, l, , l, , l, l, , rattle snake., Germinal layers are ectoderm, endoderm and, mesoderm which differentiate at the time of, gastrulation in a developing embryo, through, which the development of all the tissue and organ, system takes place., Diploblastic animals are with two germ, layers– ectoderm and endoderm, eg. porifera and, cnidaria., Triploblastic animals are with three germ layers–, ectoderm, endoderm and mesoderm, eg., platyhelminthes to chordates., Development is of two types– direct and indirect., In direct development without any intermediate, stage the young ones resembles the adult in all, respects. Eg. Silver fish., In indirect development young ones do not, resemble the adults. The young ones pass through, many intermediate stages before obtaining the shape, of the adults. The phenomenon of passing through, different juvenile stages during transition from, larval to adult stage is called metamorphosis., Metamorphosis is found in many invertebrates,, protochordates, some fishes & amphibians., Animal kingdom can be divided into two major, groups – non chordates which does not possess, notochord and chordate which possess notochord, at least in some stage of their life.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŢŐńśŚĽŐňďŕť– ŚŕĚňęř– ·– ►ńďřřĽěĽĘŐň– Őě– ○ňĽŇďńř–, l, , l, , l, , l, , l, , l, , About 95 percent of animals are without backbone, and are called invertebrates while the animals, having a backbone are called vertebrates, contributing five percent., Animal kingdom is divided into two, subkingdoms–protozoa and metazoa (Refer, flowchart on page 68)., Protozoa are the most abundant animals in the, world in terms of numbers and biomass. Their, principal importance is as consumers of bacteria, (prokaryotes)., Protozoa are defined as singlecelled eukaryotic, organisms, that feed heterotrophically and exhibit, diverse motility mechanisms., Metazoa are multicellular eukaryotes which are, divided into 3 branches—mesozoa, parazoa and, eumetazoa., Mesozoa are minute ciliated worm like animals, with out any tissue differentiation., , l, , l, , l, , l, , l, , 69, , Parazoa are those animals that for the most part, lack a definite symmetry and posses neither tissues, nor organs. They are mostly comprised of the, sponges, phylum porifera., Eumetazoas are those animals that have a definite, shape and symmetry and in most cases tissues, organized into organs and organ systems., Eumetazoans are further subdivided into two, subgroups—radiata (having radial symmetry) and, bilateria (having bilateral symmetry)., Radiata are radially symmetrical, denticulate, diploblastic animals with few organs. These are, classified under two phyla – coelenterata and, ctenophora., Bilaterally symmetrical triploblastic animals, w ith orga n sys tem, s ub divid ed into tw o, divisions– protostomia and deuterostomia., These divisions are based on the differences in, embryonic cleavage patterns, fate of blastopore, and coelom formation., , Table : Few important infective stages in animal kingdom., 1., , Sporozoites, , :, , 2., , Microfilariae, , :, , 3., , Quadrinucleated, cyst (cystic stage), , :, , Infective stage of Entamoeba histolytica from old host to new host through, contaminated food and water., , 4., , Trophozoites, , :, , Infective stage of Entamoeba gingivalis which is directly transmitted by, kissing or contaminated tooth brush., , 5., , Embryonated egg (egg :, with IInd stage juvenile), , It is infective stage of Ascaris lumbricoides from soil to new host (man), , 6., , Metacyclic stage, , :, , Infective stage of Trypanosoma gambiense from salivary gland of tse, tse fly to man., , 7., , Bladder worm/, cysticercus, , :, , Infective stage of Taenia solium (Tape worm) from pig muscle to man i.e.,, from secondary host to primary host., , 8., , Onchosphere/, Hexacanth, , :, , Infective stage of Taenia solium (Tapeworm) from primary host (man), to secondary host (pig), , 9., , Miracidium Larva, , :, , Infective stage of Fasciola hepatica (liver fluke) from sheep egg to the, secondary host (snail), , 10., , Metacercaria, , :, , Infective stage of Liver fluke to primary host (sheep), , Infective stage of Plasmodium which infect man and transmitted from, salivary gland of mosquito ( O, + Anopheles), , Infective stage of filaria worm (Wuchereria bancrofti). It is transmitting, stage from blood of man to Culex mosquito and again into the blood of, new host (man)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 71, , ▓ŕŐŚŐŮŐď–, , Chapter 13, , Protozoa, l, , l, , l, l, , l, l, l, l, , l, , l, l, l, , l, l, , l, , Protozoa are singlecelled microscopic eukaryotic, organisms that are noted for their ability to move, independently., Protozoa are members of the kingdom protista,, along with algae (plantlike), and slime molds,, and water molds (Fungilike)., Protozoa are sometimes referred to as animallike, protists., Biologist have identified about 65,000 species of, protozoa, almost half which are extinct species, from fossils., Protozoology is the scientific study of protozoa., Goldfuss (1817) coined the phylum name protozoa., Protozoa exhibit protoplasmic level of, organization., The complexity of protozoa sets them apart from, the relatively simple structures of bacteria and, viruses., Protozoa live in many different environments;, they can drift in the ocean, creep across vegetation, in fresh water rivers and ponds, crawl in deep, soil, and even reproduce in the bodies of other, organisms., Majority of protozoa are solitary but some like, Volvox & Proterospongia are colonial., Most protozoa are heterotrophic i.e., obtain their, nutrients by ingesting small molecules or cells., These particles are usually broken down in food, vacuoles which is a membranebound chambers, that contain digestive enzymes., Many species are freeliving, while others are, parasites., Freeliving species live in any habitat where water, or moisture is available at some time during the, year., Parasitic or commensal protozoa usually have, complex life cycles that take place in the cells,, , l, , l, , l, l, , l, , l, , l, l, , l, l, l, l, , tissues and bloodstream of their host. Several, species cause serious human diseases, including, malaria, amoebic dysentery and giardiasis., Common parasitic protozoa are Entamoeba,, Trypanosoma, Giardia, Trichomonas, Leishmania,, Plasmodium etc., Many freeliving species have a localized region, of pigment called an eyespot. Eyespots detect, changes in the quantity and quality of light., Common free living protozoans are Amoeba,, Euglena, Volvox and Paramecium., Many species make up zooplankton, a population, of organisms that constitutes one of the primary, sources of energy in aquatic ecosystems. They are, the beginning of the food chain., All protozoa can reproduce asexually, usually by, binary fission. During binary fission, a protozoan, divides into two identical individuals., Some species reproduce by multiple fission, a form, of cell division that results in a number of identical, individuals., While all species can reproduce asexually, a few, also reproduce sexually, through conjugation., During conjugation, individuals from opposite, mating strains pair and exchange genetic, material (DNA). Conjugation in protozoa is more, complex than in bacteria., Many species have physiological mechanisms for, monitoring conditions in their environment., Certain protozoan species also sense physical and, chemical changes or obstacles in their environment., Most protozoa are separated from their environment, only by their cell membrane., They can survive in extreme (harsh) conditions, due to their ability to form cysts. A cyst is a, dormant form characterized by a hard external, covering in which metabolic activity has ceased.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 72, , l, , l, , l, , l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Many species form cysts in response to changes, in the environment, such as nutrient deficiency,, drought, decreased oxygen concentration, or pH, or temperature changes., When favourable environmental condition return,, a protozoan emerges from the cysts and resumes, metabolic activity., Osmoregulation takes place in protozoa with the, help of contractile vaccole (present in the free, living forms but absent in parasites)., Locomotor organelles in protozoa are– finger like, pseudopodia or whip like flagella or hair like, cilia or absent., Gaseous exchange and excretion occurs by, diffusion through body surface., The first prokaryote evolved more than 3.5 billion, years ago and about 1.5 billion years ago the, first eukaryotic organisms evolved. Protozoa are, the descendants of these early eukaryotes., The first eukaryotes probably evolved through, endosymbiosis, a process in which one prokaryote, lives inside another and gradually both host and, guest become dependent on one another., A convenient way to classify protozoans is based, on the way they move i.e., locomotion : the four, phyla of protozoans are :, – Phylum sarcomastigophora, move by flagella, and pseudopodia., – Phylum ciliophora (ciliophorans) or ciliates,, move by hairlike cilia., – Phylum cnidospora, a spore producing, protozoa., – Phylum sporozoa (sporozoans) do not move, by themselves at all., Sarcomastigophora is divided into 3 classes , mastigophora, sarcodina and opalinata., , l, , l, , l, l, l, , l, , l, l, , l, l, , l, , l, , MASTIGOPHORA, l, l, , l, l, , Mastigophora is divided into phytoflagellata and, zooflagellata., The 2,500 species that make up the phylum, zoomastigina are characterized by the presence of, one or more flagella, long, hairlike structures that, are made up of microtubules., Zooflagellates are protozoans that move by means, of flagella., Some zooflagellates are freeliving, freshwater, or marine organisms., , l, , l, , l, , Many can live inside other organisms in symbiotic, relationship (a relationship in which two different, organisms live closely together; it can be either, beneficial or harmful to the organism)., The symbiotic relationship may be : mutualistic, relationship both organisms benefit, parasitic, relationship causes harm to the host., Euglena is called phytoflagellate as it possesses, both chloroplasts as well as flagella., Euglena is a connecting link between animals &, plants., Nutrition in Euglena is myxotrophic, when light, is available it is photosynthetic, in darkness it is, saprophytic absorbing food from surrounding water., Euglena (commonly called plant animalcule), contains chlorophyll, yet it resembles animals,, because it possesses a contractile vacuole near, cytopharynx., Reaserve food is stored in the form of paramylum, or paramylon in Euglena., Asexual reproduction in Euglena occurs by, longitudinal binary fission, no sexual, reproduction observed., Some zooflagellates are parasitic organisms that, cause disease in humans., The zooflagellate Trypanosoma causes african, trypanosomiasis, “african sleeping sickness”, in, humans. It produces toxins that destroy red blood, cells, causing the host to become weak. This disease, if left untreated eventually attacks the host’s, nervous system, causing death., This disease effects all large mammals, including, humans in some parts of Africa. The disease is, spread by the bite of the tsetse fly., Another species called Trypanosoma cruzi, causes, Chagas’ disease. It is transmitted by an insect called, the “kissing bug”, patients suffer from fever, and, heart damage., The Trichonympha lives in the guts of termites,, and help the termite digest cellulose in wood. This, is a mutualistic relationship, they both benefit from, the relationship., Euspundia, characterized by lesions upon skin, and mucous membrane of nose, mouth, pharynx,, (hence called nasooral leishmaniasis) is caused, by Leishmania brasiliensis., Leishmania donovani causes kalaazar (also called, dumdum fever). Infection chiefly occurs in spleen
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 74, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , and liver, secondarily in bone marrow & intestinal, villi., Leishmania is a digenetic blood flagellate whose, intermediate host (vector) is sandfly belonging, to genus Phlebotomus., Giardia, commonly nicknamed as the Grand old, man of the intestine is a diplomonadid parasitic, flagellate occurring in the intestine of man and, other animals., Giardia was discovered by Leewenhoek in his, own stool in 1681., Giardia causes diarrhoea or giardiasis (very loose, and frequent stool containing large quantity of fat),, which is accompanied by flatulence, abdominal, pain, loss of appetite, weight loss etc., , SARCODINES, l, l, , l, l, , l, , l, , l, l, , l, , Biologists have classified 40,000 species of, protozoa in the phylum sarcodina., Sarcodines are grouped into four types– amoebids, (eg. Amoeba, Entamoeba etc), radiolarians (eg., Acanthometra etc), foraminiferans (eg. Elphidium,, Globigerina etc) and heliozoans (eg. Actinophrys)., Sarcodinians are protozoans that move by, extending lobes of cytoplasm., The lobes of cytoplasm that sarcodinians extend, are called pseudopods (pseudopodia), which, means “false foot”., A pseudopodia forms when endoplasm, the inner, portion of cytoplasm, pushes the ectoplasm, the outer, layer, forward to create a blunt, armlike extention., Sarcodines include hundreds of species of, Amoebas, which inhabit fresh water, salt water,, and soil. Some can even live on mud, rocks, and, other surfaces in shallow, slow moving streams, and ponds., Sarcodines live on other protists, which they engulf, (eat) by phagocytosis., When a sarcodine feeds, it surrounds the food with, its pseudopodia. A portion of the cell membrane, then pinches together and surrounds the food in a, food vacuole, in a process called endocytosis., Enzymes from the cytoplasm then enter the vacuole, and digest the food. Undigested food leaves the, cell in a reverse process called exocytosis., Most fresh water sarcodines have contractile, vacuoles, an organelle that removes excess water, from the cell., , l, , l, , l, , l, , l, , l, l, , l, l, l, , l, l, , l, l, l, , When conditions are unfavorable, amoebas survive, by becoming hard cysts. The cysts can withstand, drought, heat, or being eaten by other organisms., Not all sarcodinians are soft “naked”; many, have hard shells or test of calcium carbonate, or silica and are called foraminiferans and, radiolarians., Most petroleum bearing regions shows the, presence of foraminiferans and radiolarians in, the fossil state., Most hard shell sarcodinians live in the ocean,, and are important food sources for many marine, animals., When hard shelled sarcodinians die, their shells, sink to the bottom of the ocean making huge, deposits of limestone called chalk., The most famous chalk deposits are the Cliffs of, Dover on the coast of England., The great Pyramids of Egypt were built with, stones quarried from limestone beds that are made, from a large foraminiferan., Amoeba was discovered by Russel von Rosenhoff, in 1755., Body of Amoeba is covered by plasmalemma, a, trilaminar and selectively permeable membrane., Plasmalemma is excretory as ammonia diffuses, out through it and respiratory as diffusion of, oxygen and carbon dioxide takes place through it., The type of pseudopodium found in Amoeba, proteus is lobopodium., Pseudopodium at its forward end gets its firm, consistency by hyaline cap which is made of, ectoplasm., Pseudopodia in Amoeba are meant for feeding, and locomotion., Pseudopodia are found in Amoeba and leucocyte, of higher animals., Locomotion of Amoeba is known as ‘amoeboid, movement’., Table : Theories of amoeboid movement, Theory, Scientists, Surface tension, Rolling movement, Walking movement, Solgel, Folding and unfolding, Contractionhydraulic, , Berthold (1886), Jennings (1904), Dellinger (1906), Hyman (1917), Goldacre and Lorch (1959), Rinaldi and Jahn (1963)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŕŐŚŐŮŐď–, l, , l, , l, l, l, l, l, l, l, , l, , l, l, l, l, , l, l, , l, , l, l, , Amoeboid movement is a form of cytoplasmic, streaming, the internal flowing of a cell’s, cytoplasm., Amoebas move by extending part of their cell, membrane into a lobe, or pseudopodia, that can, attach to a surface. Then, cytoplasm streams into, the pseudopodia and pulls the organism forward., This movement is called amoeboid movement., Solgel theory of amoeboid movement was first, given by Hyman supported by Pantin and Mast., Amoeba has no skeleton., Contractile vacuole in Amoeba is concerned with, osmoregulation, i.e., removal of excess of water., If an Amoeba is placed in distilled water, its, contractile vacuole works faster., If an Amoeba is placed in salt water, its contractile, vacuole will disappear., If marine Amoeba is shifted to fresh water, it, swells and may burst., Contractile vacuole of Amoeba is analogous, (similar in function) to uriniferous tubules of, frog., An Amoeba transferred from a container X to, another container Y developed a new contractile, vacuole, but the vacuole disappeared again when, the Amoeba was transferred back to the container, X. The containers X and Y respectively contain, marine and freshwater., Mode of nutrition in Amoeba is holozoic i.e.,, Amoeba is heterotrophic., Amoeba ingest food by import, circumfluence,, circumvallation or invagination., Digestion in Amoeba is intracellular., Food vacuole of Amoeba is analogous to the, alimentary canal of an animal or gastrovascular, cavity of Hydra., The contents of food vacuole in Amoeba first, becomes acidic then alkaline., The behaviour of Amoeba involves the manner in, which responds to the environmental conditions, (called taxes)., Different taxes with respect to kind of stimuli, are – thermotaxis (temperature), phototaxis (light),, thigmotaxis (touch), chemotaxis (chemicals),, galvanotaxis (electric current), geotaxis (gravity), and rheotaxis (water current)., Amoeba proteus does not reproduce sexually., Binary fission in Amoeba takes place when food, , l, , l, , l, l, , l, , l, , l, , l, l, , l, l, l, , l, l, l, , l, , l, , l, , 75, , is abundant and temperature is suitable. It is, completed in 30 minutes., Multiple fission or sporulation takes place during, unfavourable condition after encystment. There are, three layers of cysts., Lack of oxygen and food induces encystment,, products of multiple fission are called, ‘amoebulae’., Amoeba regenerates from nucleated bits., Lamble (1859) discovered E. histolytica. Friedrick, Losch, a Russion zoologist, discovered its, pathogenic nature in 1875., E. histolytica is a pathogenic intestinal parasite, occurring in the colon of man and causes, ‘amoebic dysentery or amoebiasis., It lives in the large intestines, where it secretes, enzymes that attack the intestinal lining and causing, deep ulcers., Affected individuals feel intense pain, and, complications arise when the amoebas are carried, by the blood to the liver and other organs., E. histolytica has only one host and so, monogenetic and completes its life cycle in humans., E. histolytica occurs in two forms: magna, (trophozoite) which is pathogenic and found in, the mucosa and submucosa of intestine forming, ulcers, and minuta which is nonpathogenic form, and found in the lumen of intestine., Its adult is called trophozoite and is monopodial., Trophozoite of Entamoeba reproduces by binary, fission., Minuta form encysts. A mature cyst is called, quadrinucleate cyst. It has four nuclei and two, chromatoid bodies., The reserve food material in cyst of E. histolytica, is glycogen., Quadrinucleate cyst is the infective stage., Contractile vacuoles are not present in E., histolytica since it inhabits an isotonic, environment of intestine., The tetranucleate cysts of E. histolyitca constitute, the transmittive or infective stage. It damages, the intestinal wall by enzyme histolysin., Entamoeba coli inhabits human colon. It is a, commensal parasite and does not produce any, disease., Entamoeba histolytica causes amoebic dysentery, or amoebiasis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 76, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Entamoeba gingivalis is a parasite of human teeth,, found in the abscesses of gum and in pus pockets, of pyorrhoea bleeding gums., Cyst is not formed in E. gingivalis and infection, occurs by direct contact like kissing., , CILIATES, l, , l, , l, l, l, l, l, , l, , l, , l, l, l, l, , l, l, l, l, , The 8,000 species that make up the phylum, ciliophora swim by means of cilia, which are short,, hairlike cytoplasmic projections that line the cell, membrane., The cilia is used for movement by beating like, oars ( = a long shaft of wood for propelling a boat, by rowing) to propel the protists., Some kinds of ciliates have specialized cilia shaped, like teeth, paddles, or feet., Ciliates have the most elaborate organelles of, any protozoa., Most ciliates live in freshwater. A common, freshwater ciliate is the Paramecium., Protozoan both eats and swims through water, with it’s cilia., When eating, the cilia sweeps food particles, such, as microscopic algae and bacteria, into the oral, groove. In the oral groove, the mouth pore opens, into a gullet, which pinches off around them to, form a food vacuoles., The food vacuoles move inside the cytoplasm where, nutrients are extracted, it ejects the waste through, an opening called the anal pore., All protozoans have contractile vacuoles. These, are an important adaptation for living in water., Contractile vacuoles collect excess water (osmosis), and pump it outside the cell body., Paramecium is a holotrichous ciliate protozoan., Hill (1752) discovered Paramecium., Paramecium is commonly called as ‘Slipper, animalcule’., Paramecium have a protective covering over their, cell membrane, it is a clear, elastic layer of protein,, called a pellicle., Trichocysts are peculiar bottleshaped organelles, present in the ectoplasm of Paramecium., Trichocysts are the organelles of offence and defence., Paramecium is heterokaryotic (dimorphic nuclei)., Micronuclei, one (P. caudatum), two (P. aurelia), and several (P. multimicronucleatum) are only, concerned with reproduction., , l, , l, l, l, l, , l, l, l, l, l, , l, , l, l, l, , l, , l, l, , l, l, l, , Oral apparatus or food apparatus consists of, cytopharynx and cytostome (mouth), cytopyge, or cytoproct (anus)., Nutrition or food intake in Paramecium is holozoic., Paramecium is a filter feeder., Paramecium has two contractile vacuoles which, control osmoregulation., Most favourite food of Paramecium is, Tetrahymena, another ciliate protozoa used in, biological research., Digestion is intracellular in Paramecium., Respiration and excretion of Paramecium are, through general body surface., Paramecium shows negative response and moves, against water current., Paramecium also have two distinct kinds of nuclei, (multinucleate) – macronucleus and micronucleus., The large macronucleus (containing multiple, copies of DNA) controls ongoing metabolic, functions of the cell (the brain) and asexual, reproduction., The smaller micronucleus is involved in genetic, exchange during sexual reproduction by, conjugation the joining of two opposite mating, strains and exchanging genetic material., Paramecium reproduces asexually by transverse, binary fission and nuclear reorganisation., In binary fission, macronucleus divides amitotically, and micronucleus mitotically., Binary fission occurs during favourable condition., It is faster multiplication, completes about in half, an hour (upto three divisions per day)., Paramecium undergoes several kinds of nuclear, reorganization such as conjugation, autogamy,, cytogamy, endomixis and hemixis. In all these, processes the macronucleus breaks into many parts, and disintegrates., In Paramecium nuclear reorganization takes place, for rejuvenation., Conjugation occurs between two mating types of, same species of Paramecium. It is a modified form, of cross fertilization., Conjugation of Paramecium involves exchange, of micronuclei., Each Paramecium (exconjugant) at the end of the, conjugation produces four daughter paramecia., Autogamy is a process of selffertilization. It, occurs in a single animal of P. aurelia.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŕŐŚŐŮŐď, l, l, l, , l, , l, l, l, , l, l, , Autogamy results in the production of two, daughter paramecia from each., Cytogamy occurs in P. caudatum. The two, cytogamonts do not exchange their male pronuclei., Endomixis occurs in P. aurelia. It is asexual, reproduction and one individual produces four, daughter paramecia., Paramecium has Kappa, Lambda, Mu and Pi, particles in cytoplasm. They differentiate, paramecia between sensitive and killer forms., Although genetic material is exchanged during, conjugation, no new cells are produced., Following conjugation, each Paramecium divides,, producing four genetically identical paramecia., Exchange of genes can enable organisms to adapt, better to changing environments, the four offspring, are genetically different from either original, paramecium., Balantidium coli is a ciliate protozoan parasite in, colon and caecum of man., Balantidium cause ‘Balantidial dysentery or, Balantidiasis’., , SPOROZOA, l, , l, l, l, , l, , l, l, , l, , The name sporozoan comes from the fact that when, they are immature, they are surrounded by thick,, sporelike walls., All species in the phylum sporozoa have adult forms, with no means of movement., Most sporozoans are sporeforming parasitic, (harmful) protozoans., Adult sporozoans have no structures for movement., Immature sporozoans, called sporozoites, can be, transmitted through fluids from one host to, another., Sporozoans cause many human diseases, including, malaria. The protozoan that causes malaria is, named Plasmodium, and is transmitted by female, mosquitoes (Anopheles)., Malaria means ‘bad air’. It is a communicable, disease., There are about 60 species of Plasmodium. Only, four species causes malaria in man. They are :, Plasmodium vivax (the most common species), P., ovale, P. malaria and P. falciparum., Malaria is a very serious disease characterized, by severe chills, fever, sweating, fatigue, and, great thirst., , 77, , Table : Types of malaria, Disease, Causative agent, Tertian malaria, Plasmodium vivax, Benign tertian malaria, Plasmodium vivax, Vivax malaria, Plasmodium vivax, Mild tertian malaria, Plasmodium ovale, Ovale malaria, Plasmodium ovale, Subtertian malaria, Plasmodium falciparum, Estivoautumnal malaria, Plasmodium falciparum, Malignant tertian malaria Plasmodium falciparum, Cerebral malaria, Plasmodium falciparum, Black water fever, Plasmodium falciparum, Quartan malaria, Plasmodium malariae, Quotidian malaria, Mixed infections, l, , l, l, l, l, , l, l, l, , l, l, l, l, l, l, , One way to reduce human deaths (2.7 million, annually) from malaria is to control mosquito, populations. Without the mosquito host, the, Plasmodium protozoan cannot complete their life, cycle., Plasmodium was discovered by Charles Laveran, in 1880., Lancisi first suspected a relationship between, mosquito and malaria., Ronald Ross (1897) discovered (confirmed), relationship between malaria and mosquito., In 1897 Ross discovered oocytes of Plasmodium, in the stomach of mosquito at Secunderabad in, India. He got Nobel Prize in 1902., Grassi (1898) described the life history of the, parasite in female Anopheles mosquito., Shortt and Garnham (1948) are associated with, the discovery of life cycle of malarial parasite., Plasmodium is an endoparasite, blood parasite,, intracellular parasite, pathogenic parasite and, digenetic parasite. (Principle host : man; and, secondary/intermediate/primary host : mosquito), Asexual cycle is passed in man by a process termed, schizogony (schizogony in liver and RBCs)., Schizogony is a type of multiple fission., Preerythrocytic and exoerythrocytic cycles occur, in liver cells and involve schizogony., Cryptozoites and metacryptozoites are produced, in respective cycles., Exoerythrocytic cycle is absent in Plasmodium, falciparum., Sexual cycle is completed in mosquito involving, gametogony and sporogony.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 78, , l, , l, l, , l, l, l, l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Stage of Plasmodium infective to man is, or the, stage of Plasmodium injected by mosquito into, human blood is sporozoite., Sporozoite directly goes to parenchyma cells of, liver., Incubation period is the duration between the, initial sporozoite infection and the first appearence, of malarial symptoms. It is about 14 days in P., vivax, 30 days in P.malariae, 14 days in P. ovale, and 12 days in P. falciparum., Erythrocytic cycle occurs in RBCs., Signet ring stage, amoeboid stage (adult, trophozoite) and schizogony occurs in RBCs., Haemozoin is the unused hematin, it forms toxic, malarial pigment., The cytoplasm of RBCs with trophozoite contain, various pigment granules: Schuffner’s dots in P., vivax, Ziemann’s dots in P. malariae and Maurer’s, dots in P. falciparum., Haemozoin causes chill and body pain. Malarial, parasites can be obtained in large numbers in blood, from a person when temperature rise with rigor., Gametocytes of malarial parasite are developed, from merozoites in RBCs of man., There are two types of gametocytes :, megagametocyte (female) and microgametocyte, (male)., , l, l, l, l, l, , l, l, l, l, l, , l, , l, , l, , Sexual phase in the life cycle of Plasmodium occurs, in the gut of mosquito., Gametocytes reach the stomach of female, Anopheles mosquito by sucking human blood., Megagametocyte produces only one gamete from, each., Microgametocytes undergo exflagellation, produce, 6–8 motile microgametes having haploid nuclei., The motile zygote formed by fertilization, (anisogamy) of macrogamete by a microgamete is, called ookinete., Ookinete penetrates the stomach wall and forms, encysted zygote called oocyst or sporont., Oocyst undergoes sporogony which is meiosis, followed by mitosis., Sporogony produces about 10,000 sporozoites from, each oocyst and they migrate to the salivary gland., Cerebral malaria is drug resistant and fatal., Gambusia (mosquito fish) feeds on larvae and, pupae of mosquito. This fish is used in biological, control of mosquito., 20th August is malaria day. Ministry of Health,, Government of India started National Malaria, Eradication Programme (NMEP) in the year 1953., Malaria is usually cured with a drug derived from, the Cinchona tree, (native to the America), called, quinine., A biolumniscent protozoa is Noctiluca.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 79, , ░ŐňΦ►ĺŐŕęďŚĚř–, , Chapter 14, , Non-Chordates, l, , l, , l, , l, , l, , l, , l, , Nonchordates are animals without notochord., Notochord is an elastic skeletal rod lying, lengthwise beneath the nerve cord and above the, alimentary canal in the embryos or adults of all, chordate animals., Notochord is found in both adult and larval, lancelets but in adult vertebrates it is largely, replaced by the vertebral column., Hence all the nonchordates are invertebrates, whereas all the invertebrates are not non, chordates. This means ®, Invertebrates – Protochordates = Nonchordates., Invertebrates are essential for maintaining the, functions of ecosystem for many reasons. For, example :, –, They form an integral part of the food web., –, They recycle organic matter, feeding on faeces, or dead plants and animals., –, They make up the bulk of parasite species, (along with microorganisms such as bacteria, that regulate animal and plant numbers)., Invertebrates is a term coined by Jean Baptiste, Lamarck to describe any animal without a spinal, (vertebral) column or backbone., Lamarck divided invertebrate into two groups–, the insecta and the vermes, but they are now, classified into over 30 phyla, from simple organisms, such as sponges and flatworms to complex animals, such as arthropods and molluscs., All the phyla which are nonchordates (like, porifera, cnidar ians, platyhelminthes,, nematodes, annelida, arthropoda, mollusca &, echinodermata) are invertebrates along with, two of the three subphyla in phylum chordata:, urochordata and cephalochordata. These two,, plus all the other known invertebrates, have only, one cluster of Hox genes, while the vertebrates, , have duplicated their original cluster more than, once., , PORIFERA, l, l, , l, l, , l, , l, l, , The phylum name porifera was coined by Robert, Grant., The sponges or poriferans (from the Greek poros, “pore” and Latin ferre “to bear”) are primitive,, sessile (attached), aquatic (mostly marine and few, fresh water), water dwelling filter feeders that, pump water through their bodies to filter out, particles of food matter., The study of sponges is parazoology., Sponges are asymmetrical or with radial symmetry, and diploblastic [ectoderm (pinacoderm) and, endoderm (choanoderm)]., Between pinacoderm and choanoderm lies the, interconnecting gelatinous matrix, the mesenchyme, or mesohyl., Mesenchyme consists of skeletal elements and free, amoeboid cells., Sponges have several cell types –, –, Choanocytes (also known as “collar cells”) :, Flagellated cells which function as the, sponge’s digestive system, are remarkably, similar to the protistan choanoflagellates. The, collars are composed of microvilli and are, used to filter particles out of the water. The, beating of the choanocytes’ flagella creates, the sponge’s water current., –, Porocytes : Tubular cells that make up the, pores into the sponge body through the, mesohyl. Special cells for passage of water., –, Pinacocytes : Form the pinacoderm, the outer, epidermal layer of cells. This is the closest, approach to true tissue in sponges., –, Myocytes : Modified pinacocytes which
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 80, , l, , l, l, , l, , l, l, l, , l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , control the size of the osculum and pore, openings and thus the water flow., –, Archaeocytes (or amoebocytes) : Are, totipotent cells which can transform into, sclerocytes, spongocytes, or collencytes. They, also have a role in nutrient transport and, sexual reproduction., –, Sclerocytes : Secrete calcareous or siliceous, spicules which reside in the mesohyl., –, Spongocytes : Secrete spongin, collagenlike, fibres which make up the mesohyl., –, Collencytes : Secrete collagen., –, Spicules : Stiffened rods or spikes made of, calcium carbonate or silica which are used, for structure and defence., With no true tissues (parazoa), sponges lack, muscles, nerves, and internal organs. Their, similarity to colonial choanoflagellates shows the, probable evolutionary jump from unicellular to, multicellular organisms., Sponges are multicellular grade organisms and, exhibit cellular level of organization., Sponges usually have a skeleton consisting of, spicules (may be either calcareous or silicious) or, spongin fibres., The cavity common to all sponges is spongocoel, or paragastric cavity lined with flagellated, choanocytes., Choanocytes (or collar cells) are present only in, sponges., Sponges have numerous mouthlets (ostia) and one, exit (osculum)., Sponges have no real circulatory system, however, the water current is used for circulation. Dissolved, gases are brought to cells and enter the cells via, simple diffusion. Metabolic wastes are also, transferred to the water through diffusion., Sponges have no respiratory or excretory organs;, both functions occur by diffusion in individual cells., Digestion is intracellular like protozoan. Digestion, of food takes place partially in choanocytes and, partially in wandering amoebocytes., The food is constituted by protozoans, diatoms,, bacteria, etc., coming in with water current., The chief nitrogenous waste of the sponge is, ammonia., Contractile vacuoles are found in archaeocytes and, choanocytes of freshwater sponges. The only visible, , l, l, , l, , l, , l, l, , l, l, , l, , l, l, , l, l, , l, , activities and responses in sponges, other than, propulsion of water, are slight alterations in shape, and closing and opening of incurrent and excurrent, pores, and these movements are very slow., Sponges have great regenerating power due to, archaeocytes which are totipotent cells., All sponges are hermaphrodites. Most sponges, are monoecious i.e. male and female reproductive, cells or gametes are formed in the same individual., Sponges are able to reproduce sexually (involving, gamete formation and their fusion) or asexually, (involving fragmentation, reduction bodies,, external budding and gemmules)., Gemmules (mostly found in fresh water sponge), are made up of amoebocytes surrounded by a layer, of spicules and can survive conditions that would, kill adult sponges. When the environment becomes, less hostile, the gemmule resumes growing., Sex cells (sperm and ova) arise from, undifferentiated archaeocytes., Sperm are formed from choanocytes; and oocytes, derive from choanocytes in some sponges, and, archaeocytes in others., Sperm are released into open water., Some sponges have oviparous fertilization where, sperm and eggs meet in open water. In other species, sperm are taken into the bodies of other sponges, and fertilized inside; this is known as viviparous, fertilization., The freeswimming larvae, known as, parenchymula (Leucosolenia & Clathrina) and, amphiblastula (sycon) serve as one of the main, form of dispersal for this largely sessile phylum., Vidabarine, found in sponges, is a compound, which may attack the AIDS virus directly., Sponges have a canal system and they need a, continuous current of water flowing through their, bodies for respiration, excretion, nutrition and, reproduction., Sponges have three types or canal systems:, asconoid (simplest type), syconoid and leuconoid., Asconoid sponges are tubular with a central shaft, called the spongocoel (or paragastric cavity, cavity, common to all sponges). The beating of choanocyte, flagella force water into the spongocoel through, pores in the body wall. Choanocytes line the, spongocoel and filter nutrients out of the water., Syconoid sponges, similar to asconoids, have a
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 82, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Some important examples, , Example, l, , Important notes, , Scypha, [Urn or Crown sponge (sycon)], , l, l, , l, , 2. Leucosolenia, , l, l, l, , 3. Euplectella, [Venus flower basket], 4. Hyalonema, [Glass rope sponge], , Class – Calcarea, Vase shaped, radially symmetrical., Resembles the ‘olynthus stage’ (solitary hypothetical ancestral, sponge) in the ontogeny. Shows protogyny, Have stomoblastula and amphiblastula., Vase like colonical, marine and sessile sponge., Has radial symmetry and ascon type of canal system., Further development results in the formation of stereogastrula or, parenchymula larva., , Class – Hexactinellida, Exhibit commensalism with shrimps. Given as a wedding gift in Ja, pan, symbolizing the idea “till death us do part”., Looks like a ball of glass wool with projecting tufts of glassy spicules., Class – Demospongiae, , 5. Cliona, [Boring sponge], , Its larvae bores into the shells of oyster. Hence harmful to oyster industry., , 6. Spongilla, , Fresh water sponge. Canal system is essentially of rhagon type. Shows, various shades of green colour due to presence of symbiotic algae, (Zoochlorella)., , 7. Euspongia, [Bath sponge], , l, , l, , l, , l, , Its skeleton is used for bathing found in warm shallow water of, mediterrian sea., Also called horny sponge due to consistence of their skeleton made, of spongin fibres, forming a closemeshed reticulum, Skeleton is used for removing dirt from the body surface while bathing., , The three classes of sponges are bony (calcarea, or caliispongiae), eg, Scypha; glass, (hexactinellida), eg, Euplectella; and spongin, (demospongiae), eg, Euspongia., , COELENTERATE, l, , l, l, l, , l, , Cnidaria or coelenterate is a phylum containing, some 11000 species of relatively simple animals, found exclusively in aquatic, mostly marine, environments., Leuckart (1847) coined the term coelenterate., They are the simplest metazoans., Cnidarians get their name from cnidocytes (the, nettle cell), which are specialized cells that carry, stinging organelles (nematocysts)., The nematocysts are the cnidarian’s main form of, , l, , l, , offence or defence and function by a chemical or, physical trigger that causes the specialized cell to, eject a barbed and poisoned hook that can stick, into, or entangle prey or predators, killing or at least, paralysing its victim. It also plays an important, role in locomotion, food capture etc., Out of 17, 4 common types of nematocysts are , penetrant or stenotele (largest cnidoblast,, containing poisonous proteinaceous fluid called, hypnotoxin), volvent or desmoneme, streptoline, glutinant (large glutinant = holotrichous isorhizas), and steroline glutinant (small glutinant = atrichous, isorhizas)., Another important cell type is the interstitial cell,, pluripotent cells that can transform into other cell, types such as spermatozoa, adenocytes or nerve
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , l, , l, l, l, l, l, l, l, l, , l, , l, , l, , l, , l, l, , cells, though not into epithelial or feeding muscle, cells; the latter two can only be produced by cells, of the same type. These give many cnidaria an, extraordinary capacity for regeneration. In, particular the genus Hydra serves as a model for, the research of pattern formation processes., Nematocysts or cnidoblasts (derived from, interstitial cells of epidermis) are mainly present, on tentacles, a group of nematocyst is known as, cnidom. They are absent on basal disc., Nematocyst is the characteristic feature of, coelenterate., It contains a poisonous substance called, hypnotoxin., Sensory structure of cnidoblast is cnidocil., Cnidocil is a hair like structure at the opening, of nematocyst., Contractile structure of a nematoblast is lasso., Lasso is contractile bundle of myonemes which, prevents the nematocysts from collapse., Cnidarians are highly evident in the fossil records,, having first appeared in the precambrian era., The basic body shape of a cnidarian consists of a, sac (i.e blind sac body plan) with a gastrovascular, cavity or coelenteron, with a single opening., It is composed of two layers of tissue, known as, the ectoderm and endoderm (or gastroderm), with, a gelatinous noncellular mesoglea in between them, containing only scattered cells. Thus the organisms, are considered to be diploblastic, though the, mesoglea may be homologous with the mesoderm, in other animals., The ectoderm surrounds the cnidarian’s ‘stomach’,, or gastrovascular cavity which functions as both, mouth and anus., Ectoderm also serves along with the mesogloea, as a hydrostatic supporting skeleton. Firm, skeletons are only found among polyps, which, produce lime for that purpose., Gastrodermis lines the coelenteron has five types of, cells nutritive (endotheliomuscular/gastrodermal), cells, nerve cells, interstitial cells, secretory, endothelioglandular cells and sensory cells., Nerve cells are apolar., Epidermis is made of epitheliomuscular cells,, glandulomuscular cells (adhesive material in pedal, disc), interstitial cells, cnidoblasts, sensory cells,, nerve cells and germ cells., , l, l, , l, l, l, l, l, l, , l, , l, l, , l, l, l, l, , l, l, , l, , 83, , Coelenterates radially symmetrical animals with, celltissue grade of body organisation., Radial symmetry, means that whichever way it is, cut along its central axis, the resulting halves would, always be mirror images of each other., The animals have blind sac body plan i.e., consists, a single opening which serves both as mouth and anus., The distal end of body is produced into a conical, elevation called hypostome., Mouth, surrounded by tentacles, is situated at the, apex of the hypostome., The cnidarian does not possess a true circulatory, system., Respiratory and excretory organs are absent as, all the cells are in direct contact with water., Respiration takes place through diffusion of, oxygen directly through their tissues without, specialised organs such as tracheae, gills or lungs., The gastrovascular system plays a role in the, digestion and dispersion of food and the removal, of metabolic waste: it surrounds the gastrovascular, cavity as well as its extensions in the tentacles of, polyps. Thus the gastrovascular system serves two, separate functions, digestion and transport., Digestion is both intracellular and intercellular, or extracellular., Extracellular digestion occurs with the help of, digestive enzymes poured into the gastrovascular, cavity by secretory cells., Most cnidarians are carnivores and mainly feed, upon small crustaceans or zooplanktons., Animals are ammonotelic., The movement of cnidaria is controlled by a, decentralised net of true nerve cells., Nervous system is primitive and diffuse type, without brain and is found in the form of an intra, epidermal nerve net., Sense organs are statocyst, tentaculocyst which, occur in free swimming forms (medusa)., Concentrations of nerve cells are found in the, mouth area of polyps (the hypostome), on the, tentacles and stem (pedunculus), and with jellies, a ring of nerves is often found around the screen., Members of cnidaria have lifecycles that alternate, between asexualpolyps and sexual, free, swimming forms called medusae. This, phenomenon is called metagenesis or alternation, of generation (e.g., Obelia).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 84, , l, , l, l, , l, l, , l, , l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Polyps are anchored to the substrate by their basal, discs, although a few species can move in curious, slowmotion somersaults. By nature they display, their tentacles upwards, away from the substrate., Polyps often live in large colonies., Polyp is concerned with feeding and protection also., Medusae have a hat or bellshaped appearance and, mostly swim passively with the current. Their, tentacles hang freely below their bodies. However,, they can actively swim by means of coordinated, muscle contractions against the water contained in, their gastrovascular cavity., Medusa stage is advanced to polyp because it has, great power of contractility., In metagenesis, the adult polyp forms male or, female medusae (diploid) asexually. There are, three principal asexual events:, –, budding, –, strobilation occurs when a medusa forms on, the higher (oral) end of the polyp, and is, common among scyphozoa., –, finally complete metamorphosis, from polyp, to medusa form can also occur., Asexual reproduction via budding is common, among cnidaria, particularly among the hydrozoa, class., During their life cycle flagellated planula larva, (Ob elia) is formed w hich s w ims u ntil it, encounters a firm substrate on which it anchors, itself and then passes through metamorphosis to, the polyp stage., The life cycle also possesses a number of immature, stages like hydrula, hydratuba, scyphistoma, ( = scyphula) and ephyra etc., Some groups such as coral live symbiotically with, algae, mostly dinoflagellata but sometimes, chlorophyta. By absorbing the carbon dioxide, produced by the cnidarian, utilising sunlight via, photosynthesis and releasing the oxygen, the algae, produce energyrich carbohydrates which the, cnidarian uses as its main source of food., Planula is the larval form of coelenterates., Classification of cnidarians is mainly based on, dominance of polyp and medusoid stage., There are three main classes of cnidaria: hydrozoa, (Portuguese Man o’ War, Obelia, Hydra etc.), scyphozoa (jellyfish) and anthozoa (anemones,, corals, etc.), , Hydrozoa, l, , l, l, l, l, , l, l, , l, l, l, , l, l, l, , l, , l, l, l, l, , l, l, , l, , In hydrozoa, polyps is the dominant or, only stage of the life cycle, though it usually have, both polyp and medusa stage. Eg. Hydra, Obelia,, Physalia etc., Food of Hydra is water fleas (Daphnia and cyclops)., Hydra does not have any free larval stage in the, development., Real discoverer of Hydra is Abraham Trembley., Hydra has four type of nematocysts serving, different functions. These are penetrants, volvents,, stereoline glutinants & streptoline glutinants., The nematocysts which are mainly used for offence, and defence are known as penetrants or stenoteles., These are the largest and most complex type of, nematocysts in Hydra. They are open and inject, hypnotoxin., The movement of the prey is impeded by volvents, or desmonemes., Penetrants and volvents are useful in capturing, the prey., Volvents or desmonemes are spineless and closed., They helps in capturing prey by coiling round, them., Stereoline glutinants are thread like tubes, without spines., Streptoline glutinants are used both in food, capture and locomotion., The action of nematocyst depends on enzymes,, which bring about increased osmotic pressure inside, the capsule of cnidoblast., Some Hydras have green or brown colour due to, presence of green algae Zoochlorellae and brown, algae Zooxanthellae in their nutritoepithelial cells., Gonads in Hydra are formed temporarily from, interstitial cells of epidermis., Hydra is a solitary polyp found in freshwater, (stagnant)., Hydra is diploblastic and radially symmetrical., The tentacles of Hydra help in locomotion and, food capture, so analogous (correspond, functionally) to pseudopodia of Amoeba., Myofibrils of Hydra are all smooth., Mesogloea of Hydra, secreted by both ectodermal, and endodermal cells, is a thin, acellular consisting, of a proteinaceous matrix and it can be crossed, by interstitial cells., Body cavity of Hydra, called coelenteron, serves
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , l, , l, l, l, l, , l, l, , l, l, l, , l, l, l, , l, l, l, , l, l, l, , l, l, l, , the double purpose of digestion and circulation., Various types of locomotion in Hydra are gliding,, floating, walking (erect movement with all, tentacles directed downwards using them as legs),, looping and somersaulting. etc, Locomotion in Hydra is not connected with mating., Hydra is carnivorous feeding on small crustaceans., Hydra engulfs only those animals which have, glutathione in their body tissue fluid of the prey., Digestion in Hydra is first extracellular (in, gastrovascular cavity) and then intracellular (in, endoderm cells)., Hydra has no enzymes to digest starch., Nitrogenous excretory product in Hydra is, ammonia and it is removed through general body, surface., Hydra has a nervous system, but no brain., Hydra has nerve cells but no nerves., Hydra possesses a very primitive nervous system, consisting of synaptic network of bipolar and, multipolar nerve cells., Hydra is negatively chemotropic, it avoids, chlorinated water., In Hydra reproduction is both asexual and sexual., Hydra reproduces asexually by exogenous, budding, a type of vegetative propagation, and, sexually by formation of gametes., Hydra is monoecious or dioecious. Most species (e.g.,, Pelmatohydra oligactis) are dioecious or unisexual., Fertilization occurs externally on the body by, the entry of sperm into ovum., Hydra has great regenerating capacities. A piece, of Hydra will regenerate into a full Hydra if it, contains a part of epidermis and gastrodermis and, size is not less than 1/6 mm in diameter., Hydra have single ovary in lower half and few, testes in distal/upper half., Hydra does not have any free larval stage in the, development., Obelia (sea fur) colony exhibits trimorphism, containing three types of individuals namely, hydranth, blastostyle and medusae., Hydranth is also known as gastrozooid and are, nutritive in function., Blastostyle is asexual reproductive zooids with, reduced gastrovascular cavity., Medusae is free swimming zooid with a mouth,, large number of marginal tentacles, sense organs, , l, l, , l, l, , 85, , (statocyst), marginal nerve ring and four gonads, for sexual reproduction., Physalia is also known as Portuguese Man of War., Physalia has a bladder like pneumatophore which, contains a gas gland. The gas secreted by the gas, gland helps the animal to float over the water, surface., Secretion of nematoblasts in Physalia is neurotoxin., Cormidia is a group of zooids in Physalia., , Scyphozoa, l, l, , l, l, l, l, , Scyphozoa are mostly marine, some are freshwater, forms., Medusa is dominant in scyphozoa with polyp, either absent or ill developed, eg. Aurelia (jelly, fish), Cyanea (sun jelly)., Nematoblast are present in both epidermis and, gastrodermis in class scyphozoa., Ephyra is the larval form of Aurelia., The sensory organs in Aurelia are the rophalia., Aurelia aurita is commonly known as moonjelly., , Anthozoa, l, l, l, l, l, l, , l, l, , l, , l, l, l, l, l, , Anthozoa have only polyp phase. eg. sea anemone, (Admasia), corals animals., All anthozoa are marine., No alternation of generation occur in anthozoa., Sea anemone (Metridium) shows commensalism, with Euspagurus (hermit crab)., Sea anemone is also known as sea flowers., The gastrovascular cavity of sea anaemone is, divided into chambers by endodermally formed, mesenteries., Cnidoblasts and germ cells are endodermal., Importal corals are Tubipora (organ pipe coral),, Fungia (mushroom coral), Madrepora (stag horn, coral), Astraea (star coral), Favea (stony coral),, Heliopora (blue coral), Corallium (red coral) etc., Coral reefs may be defined as the extensive mass, of coral colonies which grow continuously in size, by budding of polyps. Eg. fringing reef, atoll and, barrier reef., Coral animals secrete external skeletons of, calcium carbonate., Coral is the rocklike external skeletons., Corals may be solitary or colonial., Solitary coral is Fungia (also called mushroom coral)., Colonial corals are Astraea (star coral), madrepora, (stag horn coral), Pennatula, Gorgonia.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 86, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Pennatula is also known as sea pen., Largest tentacle is present in Cyanea arctica (about, 1 m in length)., Important reef forming corals are millepora,, tubipora, heliopora etc., Sea pancy is the common name of Ranilla., , l, , CTENOPHORA, l, l, , l, l, l, l, l, l, l, , l, , Ctenophora was established by Hatscheck, (1839)., Ctenophora is a small phylum of marine, coelenterates like free swimming and biradially, symmetrical animals having 8 meridional row of, ciliary comb ribs., They are popularly called as comb jellies,, seacombs and seagoose berries., Cnidoblast are absent with the exception of, Euchlora rubra., They possess photocytes or light producing, structures, therefore are luminescent., Tentacles, when present, are solid and possess, adhesive cells called colloblasts (= lasso cells)., Ctenophores are acoelomates., Body plan is intermediate between blind sac and, tube within tube., Animals are usually monoecious. An immature, ciliated stage larva called cydippid larva is found, in some forms., Ctenophora has two classes – tenticulate (with, tentacles), eg. Hormiphora and nuda (without, tentacles), e.g., Beroe., , l, l, l, , l, , l, , l, , l, l, l, , PLATYHELMINTHES, l, l, , l, , l, l, , l, , The term platyhelminthes (also called flatworms), was first proposed by Gegenbaur., The platyhelminthes (Greek “platy”’: flat;, “helminth”: worm) are a phylum of relatively simple, softbodied invertebrate animals., Flatworms are found in marine, freshwater, and, even damp terrestrial environments. Most are, freeliving forms, but many are parasitic on other, animals., Cephalization (differentiation of head) begins in, the flatworms., The flatworm’s cephalized soft body is ribbon, shaped, flattened dorsoventrally (from top to, bottom), and bilaterally symmetric., Flatworms are the simplest triploblastic animals, , l, l, , l, l, l, l, , with organs. This means their organ systems are, formed out of three germ layers: an outer, ectoderm and an inner endoderm with a, mesoderm between them., There is also no true body cavity (coelom) except, the gut and hence they are acoelomates which is, filled with somewhat loosely spaced mesodermal, tissue called parenchyma tissue., With about 25,000 known species they are the, largest phylum of acoelomates., Animal possesses tissue organ level of, organization and blind sac body plan., Extracellular body fluids (interstitial fluids), percolate between cells to help distribute nutrients,, gses, and waste products., There is no true circulatory, skeleton or, respiratory system, but like all other animals,, flatworms do take in oxygen., Flatworms respire at their integument; gasses diffuse, directly across their moist outer surface. This type, of system is called integumentary exchange., Digestive system is incomplete due to possessing, only one opening, reduced or absent in parasitic, form (e.g., Taenia)., Excretion and osmoregulation are brought about, by flame cells or solenocyte and protonephridia., Flatworms possesses high power of regeneration., Flatworms do have a bilateral nervous system; they, are the simplest animals to have one. Two cordlike, nerves branch repeatedly in an array resembling a, ladder (i.e ladder like nervous sytem). The head, end of some species even has a collection of ganglia, acting as a rudimentary brain to integrate signals from, sensory organs such as eyespots., Sense organ are better developed in free living, forms like Planaria., Flatworm reproduction is hermaphroditic or, monoecious, meaning each individual produces, eggs and sperm., Fertilization is internal and cross fertilization is, predominant., They usually do not fertilize their own eggs., Life cycle is indirect or complicated with one or, many larvae., Classifications of flatworms, primarily based on, differing degrees of parasitism, is divided into, three monophyletic classes – turbellaria,, trematoda and cestoda.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 87, , ░ŐňΦ►ĺŐŕęďŚĚř–, , Platyhelminthes, Divided into 3 classes, , Trematoda, , Turbellaria (Eddy worm), l, , l, l, , l, l, , l, l, , l, , l, l, l, , l, , l, , l, l, l, l, , l, , Freeliving in both fresh and marine, water, but some are commensals &, ectoparasites, Cilia on body surface, Epidermis is cellular, syncytial,, characterised by presence of special, hyaline rod shaped bodies called, rhabditis producing chemical, secretions, Body is unsegmented & leaf like, Suckers absent. Adhesive organs, ar e glanduloepidermal &, glandulomuscular, Alimentary canal with 2 branches, Simple life cycle. Development is, usually direct without any larval, stages., Eg. Planaria, Bipalium,, Thysanozoon etc., , l, l, l, l, l, l, l, , l, , Cestoda, , Endoparasites or ectoparasites, Cuticle present, no cilia, Unsegmented & leaf like body, Sucker and some times hooks, present, Alimentary canal with 2, branches, Complicated life cycle with, larval stages., Development is direct in, ect opa rasit es & u s u a l l y, indirect in endoparasites with, alternation of host., E.g. Liver fluke (Fasciola),, Schistostomata , Opisthorchis, etc., , Bipalium is the largest terrestrial turbellarian., Trematodes with only oral suckers are called, monostomes., The liver fluke has a dorsoventrally flat,, unsegmented body with two suckers, oral sucker, (anterior sucker) and acetabulum (ventral sucker)., Fasciolopsis (= Fasciola) buski, is a fluke that lives, in human stomach and duodenum in, SouthEast Asia., Opisthorchis sinensis (Chinese/Oriental Liver, Fluke) causes jaundice and liver damage in human, beings in China, Japan and Vietnam. It has two, intermediate hosts snail and fish. Cats, dogs and, pigs can also be infected., Fasciola gigantica (F. indica) is liver fluke of cattle., Paragonimus westermani is lung fluke., Body of Taenia is divided into three parts namely, scolex, neck and strobila., Scolex has a rostellum bearing two circlets of, chitinous hooks and four suckers or acetabula for, holding onto the host., Neck is the unsegmented part, new segments are, formed in this region., , l, l, l, l, l, l, l, l, , l, l, l, l, , l, l, l, l, l, l, l, l, l, , Advanced class, Endoparasites in alimentary, canal of vertebrates, Cuticle presented, no cilia &, epidermis, Body is segmented & ribbon, like, Every segment is, hermaphrodite, Suckers, hooks (on scolex), present, No alimentary canal, Complicated life cycle with, larval stages., E.g. Tapeworm ( Taenia),, Echinococcus etc., , Strobila is the main body made of proglottids., Proglottids are of three types : young, mature and, gravid., Young or immature proglottids are behind neck, and are without reproductive organs., Mature proglottids are in the middle having, reproductive organs, both male and female gonads., Gravid proglottids (rectangular in shape) are with, branched uterus containing fertilized eggs., Apolysis is the process of separation of gravid, proglottids., Body cavity is absent in tape worm, hence they are, acoelomate., Taenia has no digestive system. It completely, depends upon predigested nutrients absorbed from, the host’s gut through the cuticle., Complete absence of an alimentary canal is a, unique parasitic adaptation in tapeworm., The cuticle protects the tape worm from the host’s, digestive enzymes., Main excretory products are ammonia and fatty acids., All tapeworms are hermaphrodites, and a complete, reproductive system occurs in each mature proglottid.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 88, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Some important examples, Example, , Important notes, Class Turbellaria, , 1. Dugesia, (Planaria), , l, l, l, , Has great power of regeneration, Carnivorous, omnivorous and hermaphrodite, Gregarious (live in groups), Eggs are ectolecithal i.e., yolk is deposited on the outside, direct development, , If Planaria is cut across into two, three or more parts, each part regenerates into a complete and normal individual., Regeneration, thus, involves two complementary processes, viz., epimorphosis, in which the missing parts are, formed, and morphollaxis, in which the original parts are fit to function with regenerated parts in the new individual., A noteworthy observation is that a piece from the middle always regenerates a head towards its anterior side and tail, towards its posterior side. In other words, each piece maintains its original linear polarity. This can be explained by, the theory of metabolic or axial gradient by C.M Child .The theory holds that metabolic activity is highest in head, and gradually decreases towards the tail end., Class Trematoda, 2. Fasciola hepatica, (Sheep liver fluke), , l, , l, , l, l, , l, , l, , 3. Schistosoma, (Blood fluke), , l, l, l, l, l, l, , l, , Digenetic endoparasite. Primary and secondary host are sheep and snail (Limnaea, or Planorbis) respectively., Laurer’s canal is present and acts as sperm duct. During breeding season it, serves as vagina during copulation (which take place in bile ducts of hosts) and, receive the sperms., Hermaphrodite, hence cross fertilization is preferred, Correct sequence of various larva : miracidium (ciliated, free swimming stage), ® sporocyst (elongated sac like) ® redia (elongated, cylindrical) ® paedogenesis, ® cercaria (shows close resemblance with the adult fluke) ® metacercaria, (juvenile fluke, also called marita), Miracidium is the stage when it infects the intermediate host and primary host, is metacercaria., Causes liver rot or cirrhosis (fascioliasis), It is dioecious with well defined sexual dimorphism, Lives in hepatic portal vein of human body vessels of urinary bladder, Female permanently lodged in Gynaecophoric canal of male, Life cycle involves single intermediate snail host, Digenetic, primary host is man and secondary host is snail, Different larval stages miracidium ® sporocyst ® cercaria (no redia and, metacercaria stage), Infection causes schistosomiasis or bilharziasis, symptoms include skin rash, bronchial cough, anaemia, abdominal pain, diarrhoea., , 4. Elonorchis sinensis Life cycle involves two intermediate hosts a fresh water snail and a fresh water fish., (Chinese liver fluke), Class Cestoda, 5. Taenia solium, (Pork tape worm), , l, l, l, , l, l, l, , Endoparasite in small intestine of human beings., Digenetic. Primary host is man and secondary or intermediate host is pig or cattle., Larval stages oncosphere, hexacanth (with six hooks) and cysticercus (bladder, worm)., Secondary host acquires infection by ingesting oncospheres., Cysticercus is the infective stage to man., Causes taeniasis disease., contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , l, , l, , 6. Taenia saginata, (Beef tapeworm), , l, l, l, , l, , 7. Echinococcus, (Hyadit worm or, dog tapeworm), 8. Hymenolepis nana, (dwarf tapeworm), , l, , l, , Human bladder worm infection is called cysticercosis, symptoms include necrosis, of brain and epilepsy. Larvae settle in brain. It is caused because of auto infection, by antiperistalsis & man is the accidental intermediate host. It is more dangerous, than taeniasis., Self fertilization occur in mature proglottids, Inhabits the beaf eating population, Longer than T. solium (12m), Scolex lack rostellum and chitinous hook and uterine branches are absent,, hence called unarmed tape worm., Digenetic, man is primary host and intermediate host is cattle (sheep) and, buffaloes, Endoparasite, primary host (dog, wolf, cat) and secondary host (cattle, sometimes, man), Causes hydatid cyst in liver, lungs and other parts, , Smallest human tapeworm. 3 testes in each proglottids. No intermediate host., , NEMATODES, l, , l, , l, l, , l, l, l, l, , l, l, l, l, , 89, , Nematodes are commonly referred to as non, segmented roundworms, threadworms or, pinworms., They constitute the largest phylum of, pseudocoelomates group combined under the, superphylum aschelminthes., The name aschelminthes was proposed by Grobben, (1910) in place of the older name nemathelminthes., Phylum aschelminthes is divided into 5 classes :, rotifera,, gastrotricha,, kinorhyncha,, nematomorpha and nematoda., Rotifera are commonly called wheel (corona), animalcules., These are microscopic animals of ponds, lakes &, streams, rarely in oceans., Body wall thickened into plates or lorica into which, head may retreat., In class rotifera males are smaller than females,, so, female reproduce parthenogenetically, eg., Philodina, Rotaria., Gastrotricha are microscopic & marine animals., Body wall have cuticle bearing short spines, eg., Chaetonotus, Lepidodermella & Macrodasys., Body wall of kinorhyncha have spiny cuticle, without cilia., These are monoecious and gonads are present as, paired tubular sacs, eg. Echinoderes &, Pycnophyes., , l, l, l, l, l, l, l, , l, , l, , l, , l, , Nematomorpha are commonly called hair worms,, found in springs, eg Paragordius & Nectonema., Thick cuticle bearing small papillae is present in, the body wall., Digestive system is complete in larva but, degenerate in non feeding adults., Nematodes are commonly called as round worms, which are aquatic, terrestrial or parasitic., Body wall have cuticle, epidermis & longitudinal, muscles., Examples of nematodes are – Ascaris, Wuchereria,, Enterobius, Trichuris etc., The nematodes were originally named nematoidea, by Rudolphi (1808). They were renamed nematodes, by Burmeister (1837)., The science dealing with the study of worms, especially parasitic flatworms and roundworms is, called helminthology., Nematodes are bilaterally symmetric,, triploblastic protostomes with a tubewithintube, plan, organ system level of organization and a, complete digestive system., Roundworms have no circulatory or respiratory, systems so they use diffusion to breath and for, circulation of substances around their body., The body cavity is a pseudocoel or false coelom, (persistent blastula), which lacks the muscles of, coelomate animals used to force food down the, digestive tract. Nematodes thus depend on
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 90, , l, l, , l, , l, l, l, l, , l, l, , l, l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , internal/external pressures and body movement, to move food through their digestive tracts., Pseudocoelom contains hydrolymph and some, cells called pseudocoelomocytes., The epidermis (may be cellular and syncytial), secretes a layered cuticle made of keratin that, protects the body from drying out, from digestive, juices, or from other harsh environments, as well, as in some forms sporting projections such as cilia, that aid in locomotion., There are no circular muscles, so the body can only, undulate from side to side. Muscles usually are, present longitudinal., Digestive system is complete with mouth and anus., Digestion is mainly extracellular, generally feeds, on predigested food present in host’s intestine., Reserve food is in the form of glycogen stored in, syncytial epidermis., Excretion is brought about by gland cells or H, shaped intracellular excretory tubes/canals or, both. Some forms have protonephridia., The animals possess fixed number of cells &, nuclei throughout life (called eutely)., Nematodes have a simple nervous system, with, circumpharyngeal nerve ring and six, longitudinal nerve cords. Sensory structures, (which are poorly developed) at the anterior end, are called amphids, while sensory structures at the, posterior end are called phasmids., Sexual dimorphism is common., Reproduction is usually sexual. There is no asexual, reproduction., Males are usually smaller than females (often very, much smaller) and often have a characteristically, bent tail for holding the female for copulation., During copulation, one or more chitinized spicules, move out of the cloaca and are inserted into genital, pore of the female. Amoeboid sperm crawl along, the spicule into the female worm., Eggs may be embryonated (infective second stage, juvenile in Ascaris) or unembryonated when, passed by the female, meaning that their fertilized, eggs may not yet be developed., In freeliving roundworms, the eggs hatch into, larva, which eventually grow into adults; in, parasitic roundworms, the life cycle is often much, more complicated., The early larval stage of nematodes is called, , l, l, , l, , l, , rhabditiform or rhabdioid larva. It is generally, noninfective., In freeliving species, development usually consists, of four moults of the cuticle during growth., Nematodes commonly parasitic on humans, include whipworms, hookworms, pinworms,, ascarids, and filarids., One form of nematode is entirely dependent upon, the wasps which are the sole source of fig, fertilization. They prey upon the wasps, riding them, from the ripe fig of the wasp’s birth to the fig flower, of its death, where they kill the wasp, and their, offspring await the birth of the next generation of, wasps as the fig ripens., Nematodes are classified into two classes phasmida, (eg. Ascaris, Dracunculus) and aphasmida (eg.,, Enoplus, Mermis etc.) on the basis of presence or, absence of phasmids (Chitwood 1933)., Nematodes, , 2 class, l, l, , l, l, l, , Phasmids (caudal sensory, organ) absent, Amiphids (anterior sense, organs) of various types,, rarely pore like, No excretory system, Mesenterial tissue well, developed, Eg. Enophus, Paramermis, etc., , l, l, l, l, l, , Phasmids present, Amphids pore like, Excretory system, developed, Mesenterial tissue, weekly developed, Eg. Trichuris,, Oxyuris, Ascaris etc., , Plant parasitic nematodes, Plant parasitic nematodes include several groups, causing severe crop losses. The most common genera, are: Aphelenchoides (foliar nematodes), Meloidogyne, (rootknot nematodes), Heterodera, Globodera (cyst, nematodes) such as the potato root nematode,, Nacobbus, Pratylenchus (lesion nematodes),, Ditylenchus, Xiphinema, Longidorus, Trichodorus., Several phytoparasitic nematode species cause, histological damages to roots, including the, formation of visible galls (Meloidogyne) which are, useful characters for their diagnosis in the field., Some nematode species transmit plant viruses, through their feeding activity on roots. One of them, is Xiphinema index, vector of GFLV (Grapevine, Fanleaf Virus), an important disease of grapes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř–, , 91, , Table : Some important examples, Examples, 1. Enterobius vermicularis, [Oxyuris (Pin worm or seat worm)], , l, l, , l, , 2. Ascaris lumbricoides, [Roundworm], There are three types of migration, by Ascaris larvae–primary,, secondary and aberrant migration., Primary migration (from wall ®, hepatic ® portal ® liver ® hepatic, vein ® heart ® pulmonary artery, ® lungs), Secondary migration (from lungs, back to intestine of the host i.e.,, lungs ® bronchi ® trachea ®, pharynx ® gullet ® oesophagus ®, stomach ® intestine), Aberrant migration (from lungs, to brain, spinal cord, eyes etc.), , l, l, , l, , l, l, , l, , l, , l, , l, , l, l, , 3. Ancylostoma duodenale, [Hookworm], , l, l, , l, l, , 4. Dracunculus medinenis, [Guinea worm or madina worm of, fiery serpent], , l, , l, l, , l, , 5. Wuchereria bancrofti, [Filarial worm], , l, l, , l, , l, l, l, , Important notes, Found in large intestine and appendix. Monogenetic parasite., Causes enterobiasis or oxyurasis characterised by anal itching,, appendicitis, nervous problem., No intermediate host, Most common, monogenetic intestinal parasite of humans., Have telogonic gonads which means only the anterior part of testis, is functional. Female Ascaris is didelphic (has two ovaries), Causes ascariasis, characterised by anaemia, diarrhoea, pneumonia, and bronchitis, they are found world wide., Common in children., Male is smaller than female with curved tail, two pineal setae &, cloaca., Mouth is terminal in both & triradiate (surrounded by three, denticulate lips, one median dorsal & two ventrolaterals), Embryonic development takes place in soil (due to low, temperature, more oxygen and suitable moisture), Larva of first stage is not infective, second stage larva (rhabditiform), is infective., Transmission of infective stage through embryonated egg takes, place by contaminated food and water., Life span in host is of 9 12 month., Most pathogenic larva is the fourth stage in lungs., Found in the human intestine. Monogenetic., Causes itching and inflammation of skin, anaemia, retarded physical, and mental growth. Migratory larva causes pneumonia because, of foreign body larva reaction while it is in alveoli of lungs., Their larvae enter the human body by boring the skin through feet., Infective juvenile stage is filariform larvae (non feeding)., Largest nematode parasite. Gravid female are found in the, subcutaneous tissues of body and form blisters., Female is long and male is short., Intermediate host is Cyclops or water flea like Mesocyclops and, Themocyclops and primary host is man., Parasite causes itching, eosinophilia, nausea and vomiting., Found in the lymph vessels., Parasite is digenetic having secondary host Culex fatigens, Culex–, pipens and Culex unique fasiatus., Causes lymphatic filariasis or elephantiasis by blocking lymphatic, vessel and glands. Oedema typically begins in the ankle and, progresses to foot and leg., Third stage juvenile is infectious stage., Larva is called microfilariae which show day and night periodicity., By day they live in large deep seated blood vessels, but at night, or during sleep they come into superficial or peripheral vessels in, skin to be sucked by nocturnal mosquitoes., contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 92, , ŕďőĽę– ĐĽŐńŐĹť–, , 6. Loa loa, [The eye worm], , l, , l, , 7. Trichinella spirialis, [Trichina worm], , l, l, , l, , 8. Trichuris trichura, [Whip worm], , l, l, , Found in the subcutaneous tissues of eyes. Its intermediate host, is Chrysops., Causes lymphatic conjunctivitis., Intestinal endoparasite of human., Causes trichnosis, characterised by muscular pains and pneumonia, or trichiniasis., Transmitted by eating infected pork. Intermediate host is pig, or cattle., Found in the caecum and appendix. Monogenetic., Causes trichiurisis, characterized by anaemia, bloody stools and, pains., , ANNELIDA, l, l, , l, , l, , l, , l, , l, , l, , l, , Lamarck, coined the term annelida for ringed, animals., The annelida comprising the metamerically, segmented worms including the wellknown, earthworms and leeches., Metamerism is the division of body into similar, parts which is evident in the external feature of, worms., Metamerism increases the efficiency of body, movement by allowing the effect of muscle, contraction to be extremely localized, and it makes, possible the development of greater complexity in, general body organization., Each segment is marked externally by one or more, rings, called annuli. Each segment also has an outer, layer of circular muscle underneath a thin cuticle, and epidermis, and a system of longitudinal, muscles., In earthworms, the longitudinal muscles are, strengthened by collagenous lamellae; the leeches, have a double layer of muscles between the outer, circulars and inner longitudinals., Anterior to the true segments lies the prostomium, and peristomium, which carries the mouth, and, posterior to them lies the pygidium, where the anus, is located., They are found in most wet environments, and, include many terrestrial, freshwater, and, especially marine species (such as the, polychaetes), as well as some which are parasitic, or mutualistic., Annelids are triploblastic protostomes with a, coelom (or coelomate), closed circulatory system, and true segmentation., , l, l, l, , l, , l, , l, , l, , l, l, , Annelids are the first animals to have a closed, circulatory system., Annelids have organ system level of organisation., During evolution, true coelom appeared for the, first time in annelids, which is formed by the, splitting of mesoderm. Therefore it is schizocoel., Oligochaetes and polychaetes typically have, spacious coeloms; in leeches, the coelom is largely, filled in with tissue and reduced to a system of, narrow canals; archiannelids may lack the, coelom entirely., The coelom is divided into a sequence of, compartments by walls called septa. In the most, general forms each compartment corresponds to a, single segment of the body, which also includes a, portion of the nervous and circulatory systems,, allowing it to function relatively independently., Respiration is cutaneous, therefore annelids must, live in moist and aquatic environments. Some, times gases are exchanged through specialized gills, or modified parapodia., There is a tube within a tube plan of the body, because animals of this phylum have a wide, fluid, filled body cavity containing other viscera that deals, with internal functions between body wall &, alimentary canal. Body wall (outer tube) and, alimentary canal (inner tube) are specialised to their, respective functions. Alimentary canal starts with, mouth & ends with anus to ingest and egest food, respectively. Whereas outer tube forms protective, structures., The digestive system is a complete tube with, mouth & anus at both ends., The vascular system includes a dorsal vessel, conveying the blood toward the front of the worm,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , l, , l, l, , l, , l, , l, l, , l, l, , l, , and a ventral longitudinal vessel which conveys, the blood in the opposite direction. The two systems, are connected by a vascular sinus and by lateral, vessels of various kinds, including in the true, earthworms, capillaries on the body wall., Blood is red due to presence of respiratory pigment, haemoglobin or erythrocruorin dissolved in, plasma. RBC’s are absent., Circulation (open type) is caused by peristalsis, or activity of heart., Excretory system consists of metamerically, disposed coiled tubes called nephridia (ectodermal, in origin)., All annelids except leeches also have chitinous, hairlike structures, called setae (used to grip the, ground during locomotion), projecting from their, cuticle. Sometimes the setae are located on paddle, like appendages called parapodia (among, polychaetes)., Hydrostatic pressure is maintained across, segments and helps maintain body rigidity,, allowing muscle contractions to bend the body, without collapsing it., The nervous system has a solid, ventral nerve cord, from which lateral nerves arise in each segment., Annelids may be monoecious or dioecious. Larva, may or may not be present, if present they are of, the trochophore type., Annelids can reproduce both sexually and, asexually by fission., Sexes separate, trocophore larva when present, during development, undergoes, metamorphosis to, reach the adult stage., Mostly cross fertilization takes place. They are, oviparous and the eggs are laid in ootheca/cocoons/, egg case., , l, l, l, , l, , l, , l, l, l, , l, l, l, l, , l, , 93, , Clitellum present in bisexual annelids is useful in, the formation of cocoon., Fertilization is external except in Hirudinaria., Classification of annelida is based on position &, arrangement of setae when present, absence and, presence of sense organs., Annelida is divided into four classes –, archiannelida, polycha eta, olig oc ha eta and, hir udinea ., Archiannelida are all marine, small with internal, segmentation & no parapodia & setae, eg., Dinophilus, Polygordius., In the development of archiannelida, lovens larva, is seen., Polychaeta is the biggest class of phylum, annelida, eg Nereis, Aphrodite etc, Nectochaeta is free swimming larva of some, polychaetes which bears rings of cilia and 3 pairs, of parapodia. Late trochophore larva of Nereis, resembles nectochaeta., Oligochaeta are commonly called earthworms,, mostly terrestrial, some in fresh water., Pheretima is the biggest genus in the class, oligochaeta., Hirudinae are commonly called as leeches, eg, Hirudu and Hirudinaria., These are terrestrial, fresh water and marine, ectoparasitic, blood sucking or carnivorous, animals., Other examples of annelida are Drawida grandis, (longest earthworth of India); Eunice [pacific palolo, worm (exhibit lunar periodicity)]; Glycera (smooth, blood worm); Sabella (peacock worm); Serpula (fan, worm); Eutyphoeus (earthworm of gangetic plains);, Ozobranchus (leech with gills); Haemadipsa (land, leech)., , Table : Some important examples, , Example, , Important notes, , Class Polychaeta (Almost all marine, occur in greatest abundance near the seashore; locomotary, structures and parapodia), During movement body colour changes from gold to peacock blue., 1. Aphrodite, (Sea mouse), l Close ally of Aphrodite., 2. Polynoe, l Several species are bioluminescent, luminescent material is secreted, (Scaleworm), by the gland cells located on surface of elytra., contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 94, , 3., 4., 5., , ŕďőĽę– ĐĽŐńŐĹť, , Chaetopterus, (Paddle worm), Arenicola, (Lungworm or lobeworm), Neries, (Sandworm/ragworm/clamworm), , l, l, l, l, l, l, l, , Lives in Ushaped parchement tubes., Smallest oligochaetes., Lives in mud or sand in U or Jshaped burrows, lined by mucus., Used as fish bait., Lives in Ushaped burrows in tidal areas of seashores., Has chitinous jaw for capturing prey., Sexual stage of animal is called heteronereis which develops in, response to hormones and possesses enlarged eyes, swimming, foliaceous parapodia and swollen gonad containing posterior half, of body called epitoke (normal anterior part is called atoke)., Trochophore larva., , Class Oligochaeta (Commonly called earthworms, mostly terrestrial, hermaphrodites, no larval stages and, therefore no metamorphosis), l Common earthworm of India, hermaphrodite., 6. Pheretima posthuma, l Ureotelic under normal soil condition but urine contains small, (Earthworm), quantities of ammonia and creatine. They are ammonotelic in water, [For more detail refer chapter, saturated soil., Morphology and Anatomy of, l Lives in burrow in moist human rich soil., Animals], l Called Nature’s of ploughman, cross fertilization., 7. Tubifex, l Reproduces only sexually., [Blood worm (because of its bright l Helps in purification of polluted fresh water., red colour)], l It can carry on anaerobic respiration., Class Hirudinea (Commonly called leeches; sanguivorous, botryoidal tissue present), 8., , Hirudinaria granulosa, (Cattle leech), The process of letting out blood by, using leech is called phlebotomy., , l, l, l, , l, , 11. Pontobdella, (Skate sucker or marine leech), , Sanguivorous (feeds on blood). Ectoparasite on cattle and humans., Hermaphrodite., Possess an anticoagulent hirudin or anticoagulin. Hirudin is, secreted by the salivary glands & prevents coagulation of blood of, host thus ensuring a continous supply of blood., Coelom is filled with botryoidal tissue. Botryoidal tissue is a, pigmented and richly vascular masses of connective tissue & excretory, in function., , P. muricata lays velvetty eggs in empty shells of molluscs and mount, to guard over them for more than 100 days till they hatch., , ARTHROPODA, l, , l, , l, , Phylum arthropoda (means jointed legs) is a group, of bilaterally symmetrical, triploblastic, tube, withintube plan, organ system level of, organisation, metamerically segmented (with, appendages on each segment) animals., Arthropods are the largest phylum of animals and, include the insects, arachnids, crustaceans, and, others., Arthropods are common throughout marine,, , l, l, l, l, , freshwater, terrestrial, and even aerial, environments, as well as including various, symbiotic and parasitic forms., Body is often divided into head, thorax and, abdomen., Head and thorax may be united to form, cephalothroax., Possess jointed appendages which were used for, locomotion, feeding, defence and sensory purposes., Appendages may be uniramous (have one single, branch or ramus) or biramous (has two primary
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 95, , ░ŐňΦ►ĺŐŕęďŚĚř, , l, l, , l, l, l, , Worm like, Primitive arthropoda, Excretory organ nephridia., Eg. Peripatus (connecting link between annelida and arthropoda), , Trilobitomorpha, , l, , 4 subphyla, , l, l, , Comprises a wholly extinct group of primitive marine arthropods, Represent fossil arthropod, Eg. Triathrus ., , Chelicercata, Body is divided into cephalothorax and abdomen., Merostomata, , divided into 2 classes, , l, , Onychophora, l, , Arthropoda, , l, , rami) and may be secondarily lost or highly, modified., Most distinctive characteristic of arthropod is their, exoskeleton containing chitin, mucopolysaccharides, and proteins, often strengthened by CaCO3 (eg. many, crustacea and millipedes)., Exoskeleton is made up of a nonliving cuticle, (secreted by epidermis) which does not grow and, must be shed at intervals (called molting or ecdysis), periodically and grows larger., Molting occurs 47 times before becoming an adult., Exoskeleton serves the purpose of forming an, armour against enemies; a protection against, dessication and a framework for support of the, softer parts and for muscular attachment., Cuticle, , l, l, , Arachnida, l, l, , l, l, l, , Formed of three layers, , Rigid and, high in, protein., , Procuticle, l, , l, l, , l, , l, l, , l, , l, , Crustacea, , External layer, Epicuticle, , l, l, , Thin, contains a, waxy material and, serves to prevent, transmission of water, and other substance;, antibacterial., , Muscles are striated or striped which are attached, to special anchorages on the cuticle and are capable, of rapid action (i.e. allows for faster contraction, times). Muscles insert into the procuticle and are, generally paired antagonistically as flexors and, extensors., The success of arthropods is related to their hard, exoskeleton, segmentation, and jointed appendages., Respiratory system is well developed and, respiration occurs through body surface, gills,, trachea or book lungs., Aquatic arthropods use gills to exchange gases., These gills have an extensive surface area in contact, with the surrounding water., Terrestrial arthropods have internal surfaces, that are specialised for gas exchange., Insects and most other terrestrial species have, tracheal systems: air sacs leading into the body from, pores called spiracles in the epidermis cuticle., Arthropods have complete digestive system with, mouth parts modified and adapted for different, methods of feeding., Arthropods have an open or lacunar circulatory, system., , l, , l, , l, , l, l, , l, , divided into 3 classes, , Flexible and, composed of, chitin., , l, , No antennae, lacking compound eye, Most with a cephalothorax and abdomen. Some with a single, body region., Most are terrestrial or aquatic., Most are predacious, Air breather, Eg. Spiders, ticks, mites, scorpions, horseshoe crabs., , Mandibulata, , Dominant arthropoda of sea, Two pairs of antennae, Two body regions (head and thorax combined into the, cephalothorax), One pair of appendages per body segment. Appendages, terminate in pinchers., Primarily an aquatic group, respiration is by gills even in terrestrial, species., Excretion through green glands, Some very unusual groups, for example, barnacles (Sacculina ), and water fleas (Daphnia), Egs. Shrimp, lobsters, crabs and cyclops etc., , Myriapoda, Diplopoda, divided into 2 classes, , Innermost layer Intermediate layer, Endocuticle, Exocuticle, , Aquatic, extinct, Eg. Eurypterus and Limulus (living fossil), , l, l, l, l, , l, , l, l, , Does not have poisonous claw., Single pair of antennae., Two body regions, head and body., Body segments fused in pairs, each apparent segment, composed of two embryonic segments., Two pairs of appendages per apparent body segment,, extending out from sides of body, Usually herbivores or detritivore and slow moving., Eg. Millipedes (Julus ), , Chilopoda, l, l, l, l, , l, l, , Single pair of antennae, Two body regions, head and body, One pair of legs per body segment, Appendages of first body segment modified into poisonous, claws., Almost all predaceous and fast moving., Eg. Centipedes (Scolopendra), , Insecta (Largest class), l, l, l, , l, l, l, l, , l, , Single pair of antenna, Three body regions (head, thorax, and abdomen), Three pairs of legs (adult insect), one on each segment of thorax, (hence called hexapoda), Most adult insects with wings., Respiration by trachae., Excretion by malpighian tubules., D e v el o p m e n t e i th er h e m i me t a bo l o u s ( i nc o m pl e t e, metamorphosis, no pupal stage) or holometabolous (complete, metamorphosis, pupal stage), Egs. Cockroach, Apis, Bombyx etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 96, , ŕďőĽę– ĐĽŐńŐĹť–, , The perivisceral body cavity is called haemocoel, and cicadas, anal circi in cockroach), simple and, as it is full of haemolymph (blood). The true, compound eyes, statocysts (for balancing), etc., coelom is restricted to the gonads., l, Antennae are absent in arachnids., l, Haemolymph containing haemocyanin, a copper l, The animals are unisexual/dioecious and exhibit, based oxygencarrying protein, is propelled by a, the phenomenon of sexual dimorphism., series of hearts into the body cavity where it comes l, Fertilization is internal in terrestrial forms and, in contact with the tissues., external in aquatic forms. The animals are oviparous., l, The heart is dorsal in position and bears, laterally paired l, Ovovivipary is occasional, e.g., scorpion., openings called ostia. Blood capillaries are absent, l, Eggs are macrolecithal, cleidoic and centrolecithal., blood flows through ill defined spaces (sinuses)., l, Most of the arthropods possess an endocrine, l, The blood is colourless in insects., system which consists of neurosecretory cells in, l, In crustacea the blood is coloured blue due to the, the brain, at the base of compound eyes and, presence of a respiratory pigment haemocyanin., glands in the thorax., l, Unlike vertebrates and some annelids, the blood of l, Hormones control reproduction, moulting and, an arthropod does not usually carry oxygen., metamorphosis., l, Excretion is brought about usually by green glands l, Development can be direct (without larval stages), in aquatic forms and malpighian tubules in, or indirect (with larval stages)., terrestrial animals. (Nephridia occur in l, In direct development, the young resembles the, onychophores)., adults and occur in the same habitat. In indirect, l, Excretory product is ammonia/urea in aquatic, development, independent larval stages occur, forms and uric acid in terrestrial species., which often show different feeding habits, live in, l, Nervous system has paired preoral ganglia, different habitats and do not resemble the adults., (cerebral and suboesophageal), connectives,, Metamorphosis occurs in such cases., commissures and a double nerve cord having l, Metamorphosis in insects is promoted by a hormone, segmented ganglia and nerves., called ecdysone hormone., l, Various sense organs found in arthropods include l, Parthenogenesis is also met in some insects like, antennae (jointed feelers, perception of odour),, honey bees., sensory hair for touch, chemoreceptors (taste l, Arthropoda is divided into 4 subphyla , receptors located in feet in insects, labium and, onychophora, trilobitomorpha, chelicercata and, maxillary palps), sound receptors (chirping crickets, mandibulata., Table : Some important examples, Examples, Important notes, Class Onychophora (Most primitive arthropods), 1. Peripatus, Connecting link between annelida and arthropoda., (Walking worm), Class Arachnida, 2. Palamnaeus, l, Body is divided into prosoma, mesosoma and metasoma., l, Venomous arthropod and feeds on insects, worm, spider etc. Male, (Indian scorpion), is smaller than female., l, Viviparous, respiration through book lungs. Shows courtship., l, Chelicerae are provided with poison gland and pedipalps in male, 3. Aranea, functions, as copulatory organ., (Spider), l, Spinnerets (spinning organs) produce silken threads for construc, tion of spider web to trap insects etc., l, Male spider are commonly smaller., l, Common spiders are : trapdoor spider (Pachlomerus); funnel web spiders, (Agelena); wolf spider (Lycosa); oral web spiders (Argiope); black window, spider (Latrodectus); venomous spider (Lactodectus meactans)., l, , contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , 4. Limulus, (King crab or Horse shoe crab), 5. Ticks, , 97, , It is a living fossil and large sized marine arthropod., , Minute creature, but larger than mites., Ectoparasites of vertebrates and provided with blood sucking mouth parts., l, Common ectoparasite tick is cattle tick (Boophilus micropus)., l, Spread diseases like Rocky mountain fever besides causing irritation., Sarcoptes scabie, l, Minute sac like animal without body division., (Human itch mite), l, Free living as well as parasites on both vertebrates and invertebrates., l, Causes scabies in human beings., l, Dust mites (Dermatofagodes farinea and D. pteronysiunus) causes, 45% of allergies. It feeds on dandruff, skin epidermis, hair etc., Class Crustacea (Dominant arthropods of sea), Cyclops, l, Possess single median eye (hence one eyed animals), l, Intermediate host of guinea worm and blood tape worm., (Water flea or cyclops), l, Fresh water, laterally compressed., Daphnia, l, Single compound eye and two nuchal (probably olfactory) organs, (Water flea), are present., l, Formed from fertilized eggs give to 4 6 generations of females, parthenogenetically., l, Cyclomorphosis (seasonal changes) occur., l, Lives inside molluscan shells., Euspagurus, l, Hermit crab and sea anemone often forms a close association,, (Hermit crab), termed commensalism. Sea anemone protects the hermit crab by, keeping its enemies away by its offensive odour and unpalable, taste. In return hermit carb carries the sea anemone from place to, place, providing varieties of food., Nocturnal, omnivorous, fresh water but bottom feeder. Abdomen ends, Palaemon, in pointed telson. Indian marine or tiger prawn is Penaeus., (Prawn), l Resembles prawn. Secretive, noctural and carnivorous., Astacus, l Greatly priced for their meat., (Cray fish), Parasite on crab causing parasitic castration. Shows retrogressive, Sacculina, metamorphosis., (Root headed barnacle), Class Myriapoda, l Fast moving, carnivorous and nocturnal., Scolopendra, l First pair of legs are poison claws., [Centipede (or hundred leggers)], l, , l, , 6., , 7., 8., , 9., , 10., 11., 12., , 13., , 14. Julus, [Millipede (or thousand leggers], , 15. Periplaneta americana, (Cockroach), (For more detail refer chapter, Morphology of animals), 16. Lepisma saccharina, (Silver fish), , Sluggish, timid and secretive., When touched or lifted they curl up in flat spiral like a watch spring., l Mostly herbivorous or saprophytic., l Stink or odoriferous gland is present., Class Insecta, Terrestrial arthropod, nocturnal (in activity), omnivorous, and shows, cannabalism. Unisexual and shows sexual dimorphism. Undergoes, paurometaboly (gradual metamorphosis) by 67 months. Indian cock, roach Blatta orientalis is small sized and female Blatta has vestigial, wings., l Glistening silvery white, fish like body (wingless). Feeds on starchy, substances. Chewing type mouth parts., l Nocturnal, commonly occurs amongst book, clothes, photoframes etc., l, , l, , contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 98, , 17. Mantis religiosa, (Praying mantis), 18. Carausius, (Stick insect of tropical forest), , ŕďőĽę– ĐĽŐńŐĹť–, , l, l, l, l, l, , 19. Phyllium scythe, (Leaf insect), 20. Schistocerca gregaria, (Locust), , l, l, l, l, l, , 21. Microtermes obesi, (Termites), , l, l, , l, l, , 22. Poecilocerus pictus, (Grass hopper), , l, l, l, , 23. Tachardia tacca, (Lac insect), , l, l, , l, , 24. Bombyx mori, (Silk moth or silk worm moth), Diseases of silkworm, • Pebrine or pepper disease Nosema, bombycis (protozoan parasite)., • Muscardine Fungal disease caused, by Isari farinosa, Spicaria pracina, etc., • Flacherie Bacillus bombycis and, Streptococcus bombycis., • Grasserie Referred to silkworm, jaundice, caused by Borrelina virus, bombycis., , 25. Musca domestica, (House fly), , l, , l, l, l, l, , l, , l, , l, l, l, , l, l, l, l, , 26. Sympetrum hypomelas, (Dragon fly), , l, l, , Carnivorous insects. Camouflaged in its green surroundings., Female eats up the male after copulation., Shows mimicry, mimics a twig to escape detection by enemies., Also called walking stick, herbivorous., Shows regeneration and parthenogenesis., Resembles a leaf., Shows mimicry with dicot leaf., Migratory allies of grass hopper., Nymph are called hoppers., Swarming occurs in them due to poor vegetation in their natural habitats., Popularly called white ants but they are neither ants nor white in colour., Cellulose is common food for which Trichonympha (a zooflagellate), helps in their digestion., Built nest called termitarium., Known to secrete special odour substances which serve as guide, lines for their back journey into the nest., Short horned diurnal insect common on Calotropis plant., Male grasshopper produces sound by rubbing edges of wings etc., Largest grass hopper is Silicofern grandis (wings span 2.5)., Scale insect with separate sexes. Produces lac., Lac, resin like substances, is secreted by larvae and female lac, insect on a number of forest trees (called stick lac)., India is biggest producer of lac., Also called mulberry silk moth. Adult moth do not feed. Females, are larger than male. Salivary gland (= labial gland) is modified, to form silk gland of larva., Male moth dies soon after copulation., Larva is called caterpiller or silkworm., Life history include egg, larva, pupa and imago., Produce silk (a natural fibrous substance containing fibroin and, sericin proteins) from coccons (pupa, chrysalis)., Silk is extracted by killing cocoon (called sericulture). Silk thread, is formed of two proteins fibroin and sericin., Different species producing silk are –, Mulberry silkworm, –, Bombyx mori, Tasar silkworm, –, Antheraea paphia, Muga silkworm, –, Antheraea assama, Eli silkworm, –, Attacus ricinii, Active in warm months and inactive during winter., Metathorax has halteres for balancing. Larva is called maggot., Transmit number of diseases like conjunctivitis, trachoma, plague,, leprosy, TB etc., Show complete metamorphosis, Stage in life history : Egg Larva (maggot) Pupa Imago (adult)., Maggot moults twice thus housefly has three larval instars., Myasis is a disease caused by maggots., Often known as mosquito hawks as mosquito form their main diet., They are prehensile., contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , l, l, , 27. Apis dorsata, (Honey bee), , l, , l, , l, , l, , l, , l, , l, , l, , 99, , Copulation occurs in flight., Both the aquatic nymph (called naiads) and adult are predaceous., Social insect lived in colony which contains workers (sterile, diploids females), queen (fertile diploid females) and drones, (fertiles haploid males)., Queen develops from fertilized egg and a larva fed on royal jelly,, drone develops parthenogenetically and worker bees develops, from fertilized eggs and make and repair hive., Queens live for five years, drone have short life span and worker, bees live for a few weeks only., Honey bee exhibit round and waggle dance to communicate for, location of food., Queen mates only once in a life time and store sperm in her, spermatheca. Drone and virgin queen takes part in nuptial flight., Royal jelly, given to queen, is produced from pharyngeal gland, of workers., Workers have pollen collecting apparatus, honey storing, mechanism and wax secreting glands (in abdomen)., Collects honey, secrete beewax. Culturing honey bee is called, apiculture., , Small nocturnal two winged insects., Mandibles are absent in males, therefore, male mosquitoes, usually, Table : Diseases caused by, feed on flower sap on nectar while female feeds on blood of, mosquitoes, animals and human., Disease, Mosquito, l Because of their blood sucking adaptation females are medically, important as carrier of viral, bacterial and protozoan infections., Malaria, Anopheles female, l Pedicel of antennae has Johnston’s organ for percieving vibrations, (Plasmodium), including those of sounds., Filariasis, Culex female, l Larva of mosquito is known as wriggler (34 days life span) &, (Wuchereria), pupa is called tumbler (27 days life span)., Encephalitis Culex and Aedes female, l Sex of mosquitoes can be determined by the form of the antennae, (Virus), and maxillary palps., Denuge fever, Aedes female, l Common mosquitoes are Anopheles, Culex and Aedes. Anopheles, (Virus), and Culex can be easily identified by their sitting position. (Culex, Yellow fever, Aedes female., body held parallel to surface while sitting, Aedes body held, (Virus), parallel to surface while sitting with black and white striped body,, Anopheles body held at an angle to the surface, dark spotted wing.), l Nocturnal ectoparasite., 29. Cimex lectularius, l Hind wings are absent. Piercing and sucking mouth part., (Bed bug), l Wingless flat insect. Ectoparasites. Eggs are called nits., 30. Pediculus humanus, l Carry germs of typhus fever. Piercing and sucking mouth parts., (Human louse), l Ectoparasite of rats and humans., 31. Xenopsylla cheopis, l Transmit Pasteurella or Yersinia pestis or germs of bubonic plague, (Rat flea), from rats to humans., Plant pests. Secrete honey dew. Called ‘ant cows’., 32. Aphis brassicae, (Cabbage aphid), Occurs in almost all types of habitat. Hard bodies insects with heavy, 33. Beetles, cuticle. Complete metamorphosis. Larva is called grubs. Eg. Lady, bird beetle (Cocinella septupunctate) etc., 28. Mosquito, , l, , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 100, , ŕďőĽę– ĐĽŐńŐĹť–, , MOLLUSCA, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , Mollusca is the second largest phylum after the, arthropods & includes predominantly marine, species., The molluscs includes a variety of familiar animals, wellknown for their decorative shells or as seafood., These range from tiny snails, clams, and abalone to, squid, cuttlefish and the octopus (which is, considered the most intelligent invertebrate)., The giant squid, which until recently had not been, observed alive in its adult form, is the largest, invertebrate; although it is possible that the, colossal squid is even larger., The scientific study of molluscs is called, malacology and the study of shell of mollusca is, called conchology., Molluscs are triploblastic, bilaterally, symmetrical, schizocoelic & unsegmented, protostomes., Mollusca refers to the bivalve shell and the soft, bodied animals within the shell., The body is often divided into a head with eyes or, tentacles, a muscular foot and a visceral mass, housing the organs and mantle., Most molluscs have a welldeveloped head,, containing high concentration of sensory and, nervous functions., Some molluscs, like the cephalopods, have, complex, sensitive eyes. Also located in the head is, the mouth region, with the radula (a rasplike, feeding organ present in many molluscs)., Radulae are diverse within the mollusca, ranging, from structures used to scrape algae off rocks, to, the harpoonlike structures of cone snails., The radula is usually toothed, and is adapted to, a wide variety of feeding styles, including, scraping, stabbing, tearing and cutting, depending, upon the species., Adjacent to the head is the large muscular foot,, which is formed from the ventral body wall and is, used primarily for locomotion, and is often, ciliated and covered with mucous glands. Mucous, reduces the friction and creates a surface for gliding, and cilia aids in movement. This is one of the, reasons why some believe that molluscs evolved, from flatworms since arthropods completely lack, external cilia and so do many annelids., , l, , l, , l, , l, , l, l, , l, , l, , l, , l, l, , l, , l, , l, , l, , The visceral mass is housed in the shell in most of, the molluscs. It holds most of the internal organs, and houses the circulatory and digestive systems., The mantle or pallium is a sheath of tissue formed, from the dorsal body wall. It surrounds the mantle, cavity, where the gills or lungs are often housed,, and its surface can assist in gas exchange., The mantle also secretes the calcium carbonate, shell in the molluscs that do have a shell. It may be, bivalve or univalve, spiral or cone like, internal, or reduced or even absent., Mantle serves a protective function and often has, retractor muscles associated with it that allows the, shell to be pulled down over the body., The principal body cavity is a bloodfilled, haemocoel., They have a true coelom (eucoelom); any coelomic, cavities have been reduced to vestiges around the, hearts, gonads, and metanephridia (kidneylike, organs)., All species of the phylum mollusca have a complete, digestive tract that starts from the mouth to the, anus., Circulatory system is mainly of open type, but some, reduced sinuses are present. Cephalopods have, closed circulatory system, e.g., squid & octopus., Blood is colourless & has amoebocytes & often a, respiratory pigment is copper containing, haemocyanin dissolved in plasma., Respiration by gills (called the ctenidia), lungs, or both, sometimes direct., Excretory organ is paired metanephridia (kidney,, organ of bojanus). The excretory matter is ammonia, or uric acid., Nervous system consists of paired cerebral,, pleural, pedal and visceral ganglia, joined by, longitudinal and cross connectives and nerves., Ganglia usually form a circumcentric ring., Sense organs include eyes and tentacles on head,, statocysts and osphradia (a chemoreceptor to test, chemical nature of water) near the base of gills., Osphradium (bipectinate means feather like) serves, as olfactory organ, arises from the mantle, adjacent, to the left nuchal lobe and situated on the left side, of the pulmonary chamber., Osphradium helps in testing the physical and, chemical qualities of entering water and also, helps in the selection of food material.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř–, , If water is foul, then its (osphradium) entry into the, mantle cavity is stopped by the closure of the left, nuchal lobe. This sensory structure is absent in, terrestrial pulmonates the land snails and slugs, and nudibranches. The gills have strong cilia that, create the water current into the mantle cavity., l, l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Reproduction sexual, dioecious or monoecious., The sex organs of molluscs are housed in the, visceral mass., The fertilized young develops into a ciliated larva, called a trochophore, which, in the more advanced, molluscs, develops into a veliger stage, which then, develops into the adult organism., Fertilization is generally external, development, is direct or through free larval forms like, trochophore, veliger, glochidium, etc., Radula, muscular foot, mantle & highly, developed eye are unique features of molluscs, which are not found elsewhere., Mollusca is divided into 6 classes monoplacophora,, amphineura (polyplacophora), scaphopoda,, gastropoda, pelecypoda (bivalve) and cephalopods., Species of monoplacophora are small, marine, with, internal segmentation, possessing conical or cap, shaped shell, e.g. Neopilina. Larva is trochophore., Amphineura or polyplacophora have broad foot, and a linear chain of eight serially overlapping, dorsal shell plates, e.g. Chiton (coat of mail shells,, sea mouse), Chaetopleura., Scaphopoda are elongated, cylindrical molluscs, almost completely enclosed by the mantle, which, secretes a single tubular, calcareous shell open at, each end, resembling the tusk of some mammals, (like elephant), e.g. Dentalium (tusk shell)., Gastropods (stomachfooted mollusc) are very, large and diverse group sharing the common, feature that during the development the visceral, hump is rotated through some 180° in an, anticlockwise direction called torsion (i.e. bilateral, symmetry in larval stage and asymmetry in adult, form). E.g. Pila (apple snail), Limax (slug), Helix, (land snail), Aplysia (sea hare) and Cypraea (cowrie)., Pelecypoda (= lamellibranchia) are bivalved, molluscs, most of which are sedentary filter, feeders that depends on ciliary current produced, by the gills to bring in food materials., Examples of bivalves are Unio, Pinctada, Teredo,, Solen (rajor clam), Pectan, Ostraea., , l, l, , l, l, , l, , l, l, , l, l, l, l, , l, l, , l, l, l, l, l, l, , 101, , All bivalves are aquatic, with the majority living in, shallow marine waters., The bivalve body consists mostly of a muscular, foot in the anterior and a series of gills (ctenidia), and a pair of siphons (if present) in the centre and, posterior part., Bivalves secrete pearls., Shell has three layers , –, Periostracum Outermost horny formed of, chiton like organic substance, conchiolin. This, layer is responsible for exterior colouration, of the shell and protects the underlying, prismatic layer., –, Ostracum (prismatic layer) Formed of, prisms of CaCO3., –, Nacreous or pearly layer Innermost layer,, secreted by whole outer surface of mantle and, formed of alternate transverse of CaCO3 and, conchiolin. Also known as mother of pearl., Umbo represents the oldest part of shell while lines, of growth represent intervals between growth stages, means indicate the age of individual., Unlike the gastropods, they have no head, no, radula and very little cephalization., A pearl is formed of a number of nacreous layers, secreted by nacresecreting cells of mantle around a, foreign body. Nacre is pearly irridescent material., The pearl of Unio is not of commercial important., Most valuable pearl is of Pinctada margritifera,, commonly called pearl oyster., Kokichi mikimota is commonly called “father of, pearl industry”., Cephalopoda (head foot molluscs) are the most, complex of the mollusca, e.g. Sepia (cuttle fish),, Nautilus, Octopus, Loligo., All cephalopoda or siphonopoda are marine and, all are predators., Cephalopods have a concentrated nervous system, and are among the most intelligent of the, invertebrates., Locomotion is either by jet propulsion or by, swimming movements., Smallest molluscs is Ammonicera rota., Slowest molluscs is Helix aspera/garden slug., Largest shell is Tridaena derasa/giant marine, clam., Largest snail is Tethys., Largest octopus is Octopus apollyon.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 102, , ŕďőĽę– ĐĽŐńŐĹť, , In some gastropods and cephalopods, the symmetry is distributed during development and they become, asymmetrical. Asymmetry is there because these molluscs undergo two processes–, (i) Coiling Coiling in shells occurs in various ways and a portion of the body coils to accommodate within the, shell. Often this results in a loss of one or more paired organs such as gills and kidneys. Coiling can be dextral, (clockwise, towards right) or sinistral (anticlockwise toward left). e.g. Pila., (ii) Torsion Torsion or twisting involves a rearrangement of the internal organs from their traditional position by, rotation of the digestive system and associated organs up to 180 degrees. Actual site of torsion is neck tissues, and structures within it. It starts much before coiling., Table : Some important examples, Examples, , Important notes, , Class Monoplacophora [Only mollusca having segmentation (internal) or metamerism], 1. Neopilina, Living fossil. Only representative of palaeozoic group of molluscs., Also connecting link between annelida and molluscs., Class Amphineura, 2. Chiton, Nocturnal and herbivorous. Have multiple sense organs osphradia,, (Coat of mail shell/sea mouse), tactile receptors, taste receptors, otocysts, pit organs etc. A trochophore, larva is present., Class Scaphopoda, 3. Dentalium, (Elephant tusk shell), , 4. Pila, (Apple snail/pond snail), , 5. Aplysia, (Seahare), 6. Patella, (true limpet), 7. Doris, (Sea lemon), 8. Limex, (Grey slug), 9. Helix, (Sand snail), , l, l, , A marine mollusc, living at moderate depth in the sublittoral., Filamentous captacula are found instead of true tentacles for as, sisting feeding function., Class Gastropoda, , Lead amphibious life, have pulmonary sac for aerial respira, tion and gill (ctenidium) for aquatic respiration., l, Osphradium of Pila is chemoreceptor, l, Eyes occur over ommatophores., l, Ammonotelic in water and ureotelic on land, l, Has conispiral shell (coiled along an erect cone) which are either, dextral or sinistral, l, Have two type of sperm eupyrene (small & functional) and, oligopyrene (large, nonfunctional), Secretes purple fluid when disturbed, which makes the animal invisible, to its enemy., Marine gastropod. Has an aspidobranch gill (feather like 2 rows of, gill lamellae.), Nudibranch and marine gastropod., l, , Terrestrial gastropod. It is a plant pest and damages seedlings, tender, shoots and leaves., Herbivorous, nocturnal terrestrial snail which is commonly found, creeping over moist and shady place., Class Pelecypoda or Lamellibranchia or Bivalvia, Edible bivalve. A ‘glochidium larva’ (parasitic on fish) and keber’s, 10. Unio, organ are present. Omnivorous and filter feeder. Marsupium is enlarged, (Fresh water mussel), water tube and act as brood pouch., contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř, , 103, , 11. Teredo, (Ship worm), , Destructive to wood in seawater., , 12. Pinctada vulgaris, (Pearl oyster), , Secretes precious pearls. The pearl is formed as a result of nacreous, secretion from the mantle around a sand particle. Pearl is formed, in about 7 years., Marine, free swimming and swims by clapping movements of shell, valves., Marine bivalve. Fixed to rocks etc by a group of adhesive byssus, threads. Development includes glochidium., , 13. Pectan, (Scallop), 14. Mytilus, (Sea mussel), , Class Cephalopoda, , 15. Sepia, (Cuttle fish), 16. Loligo, (Squid/sea arrow), , l, l, l, , l, , l, , 17. Octopus, (Devil fish), , l, l, l, , 18. Nautilus, , l, l, , Shell internal, edible cephalopod of shallow warm sea, carnivorous., Ink gland is present for escaping from enemy. Larval stage is absent., Resembles Sepia in broad structures. Edible and fast swimmer in, open waters of the sea., Abundant in pelagic marine environment where they are vora, cious predators of many organism, especially fish., Giant squid (Architeuthis) is the largest invertebrate., Bottom dweller, nocturnal and large sized cephalopod., Its poisonous saliva paralyse its prey., One of the arms generally the right arms of male is spoon shaped, and is called hectocotylized arm which is used to transfer sperms, into the female mantle cavity., A tetrabranch cephalopod, has an external coiled and chambered shell., It floats by secreting gas in the chamber. Animals lives only in, last chamber. Active at night and rest on bottom during day., , ECHINODERMATA, l, l, l, , l, , l, , l, , l, , The name echinodermata was coined by Jacob, Klein in 1938., It constitutes the only major group of deuterostome, (blastopore becomes anus) invertebrates., Echinoderms (literally means spiny or prickly, skinned) are a phylum of marine animals found at, all depths., This phylum appeared in the early cambrian, period and contains about 7,000 living species and, 13,000 extinct ones., Echinodermata is the largest animal phylum to, lack any freshwater or terrestrial, representatives., Echinoderm is closely related to the chordates, because the coelom of the animal is made from the, digestive tube, not from cell masses like the phyla, mollusca, annelida etc., Echinoderms are exclusively marine and largely, bottom dwellers, enterocoelous, triploblastic, animals., , l, , l, l, , l, , l, l, , They are pentameral, i.e, they have fivefold, symmetry, with rays or arms in fives or multiples, of five., Echinoderms possess an endoskeleton of calcareous, plates or spicules embedded in the skin., Endoskeleton of echinoderms is unique in being a, mesodermal structure instead of ectodermal, as in, other invertebrates., Each skeletal element of an echinoderm is actually, a single crystal of calcium carbonate, very finely, branched and structured., Echinoderms have been compared to living,, moving castles. Castles are made of interlocking, blocks, with a single main entrance and numerous, slit windows for air and for defence. Echinoderm, skeletons are made up of interlocking calcium, carbonate plates and spines with opening., In echinoderms, fine networks of calcium carbonate, form a structure, known as stereom., Between the skeleton plates of echinoderm, a
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 104, , l, , l, l, , l, l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , number of special structure protrude, with which, the echinoderm breaths, moves and defends itself., Typically these are tube feet, pedicellaria and gills., All echinoderms have a peculiar hydraulic water, vascular system, a modified coelom, which help, in locomotion, adhesion, respiration and food, capturing., A set of water filled canals branches from a ring, canal (a canal encircling the gut)., The canals lead to podia, or tube feet, which are, sucker like appendages that the echinoderm can use, to move, grip the substrate, or manipulate objects., It also acts in capturing of food, respiration etc., These tube feet are external and retracted by, hydraulic pressure in the water vascular system., Pedicellaria are small, snapperlike skeletal, elements., Pedicellaria help in the capture and removal of, debris and minute organisms such as larvae. In, some starfishes they also helps in capturing of, small prey for feeding purpose., Echinoderms have a spacious coelom (an open,, fluid filled body cavity lined with tissues)., Many starfish have the peculiar ability to feed by, turning the stomach inside out through the, mouth., Sea urchins scrape algae from rocks with five large, teeth arranged in a structure known as Aristotle’s, lantern., Aristotle’s lantern It is a characteristic of some, members of class Echinoidea (e.g., Echinus). In, these members, five teeth surrounding the mouth, are attached to a masticatory apparatus, called, Aristotle’s lantern, after its discoverer and because, of its resemblance to an ancient Greek ship lantern., It is situated within the test and projects slightly, through the mouth. Sea urchin uses Aristotle’s, lantern for the purpose of feeding., , l, l, , l, , l, , Echinoderms (except holothurions) generally lack, respiratory systems., The circulatory system, if present consists of a, haemal system that is derived from coelomic, sinuses., They also possess an open and reduced, circulatory system, and have a complete digestive, tube (tubular gut)., Nervous and sensory system are generally poorly, developed., , l, , l, , l, l, , l, l, , l, l, , l, l, , l, , l, , l, l, l, l, , Poorly developed sense organs include tactile, organs, chemoreceptors, terminal tentacles,, photoreceptors and statocysts., They have a simple radial nervous system that, consists of a modified nerve net (interconnected, neurons with no central organs); nerve rings with, radiating nerves around the mouth extending, into each arm; the branches of these nerves, coordinate the movements of the animal., No echinoderms has a brain, some however do have, ganglia., The sexes are usually separate. Sexual, reproduction typically consists of releasing eggs and, sperm into the water, with fertilization taking place, externally., Echinoderms are mostly dioecious, gonads large, and single or multiple., Holothurians possess a single gonad, crinoids lack, distinct gonads while asteroids and echinoids have, multiple gonads., Development is indirect through free swimming, larval forms., Echinoderms possess remarkable power of, autotomy or amputation (breaking off the injured, or unduly stimulated body parts) and regeneration., In class, asteroidea metamorphosis is extremely, rapid, taking place in about one hour., Echinoderms can be divided into five main classes , –, Asteroidea (e.g., Asteropecten, Asterias etc.), –, Ophiuroidea (e.g., Ophiura, Ophioderma), –, Echinoidea (e.g., Echinus, Diadema), –, Holothuroidea (e.g., Holothuria, Thyone etc.), –, Crinoidea (e.g., Antedon, Neometra)., Some species of asteroidea (as for example sea, stars) are unique in their ability to regenerate an, entire body from a single arm., All seastar are voracious carnivores, feeding, mainly on crustaceans, polychaetes and molluscs, and even other small fishes, and injured and dead, animal., Platasterias latiradiata is the only living species, of somasteroidea belonging to class asteroidea., Bipinnaria larva is the characteristic of class, asteroidea., Bipinnaria larva transforms into brachiolaria, larva before going to the adult stage., The members of class ophiuroidea are mostly, detritivores consuming small bit of organic debris, from the ocean floor.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , ░ŐňΦ►ĺŐŕęďŚĚř–, l, l, l, l, , Brittle stars and basket stars make up the bulk of, the members in the class ophiuroidea., Ophiopluteus larva is the free, swimming larva of, brittle stars belonging to the class ophiuroidea., The members of the class echinodea lack appendages, and includes sea urchins & sand dollars., Echinopluteus larva is the characteristic of class, , l, l, l, , 105, , echinoidea., Auricularia larva is the characteristic of class, holothuroidea., Doliolaria larva is the characteristic of class, crinoidea as well as holothuroidea., Sea lilies (belong to class crinoidea) are the most, primitive of echinoderms., , Table : Some important examples, Examples, 1. Asterias (Pentaceros), (Star fish or sea pentagon), , Important Notes, l, l, , l, l, l, l, l, , 2. Ophiothrix, (Brittle star or spiny brittle star), , l, l, , Has high power of regeneration, unisexual, Digestive glands or pyloric caeca contains four types of cells , secretory or granular cells (secrete proteolytic, amylolytic and, lipolytic enzymes); mucous cells (secretes mucous); storage cells, (store and reserve food as lipids, glycogen etc) and current, producing cells (maintains a steady flow of enzymes)., Digestion is extracellular as well as intracellular., Fertilization is external., Feeds on molluscs and destroys pearl oysters., Their dried skeletons are crushed and used as fertilizers., Largest starfish is Pyenopodia hellianthoides (30 cm in diameter)., Mouth is used for both ingestion and egestion., Jointed parts of arms or ossicles are popularly called vertebrae., , 4. Echinoarachinus, (Sand dollar or sea dollar), , Live on ocean bottom., Scrape algae to feed., l, Long barbed spines make venom for protection., l, Aristotle’s lantern is present., Flattened body. Live in sand along coastlines. Shallow burrowers., Aristotle’s lantern is present., , 5. Cucumaria, (Sea cucumber), , Bottom dweller. Has cloacal respiration and pair of respiratory trees, in the coelom., , 6. Antedon, (Sea lily/feather star), , Superficially resembles a herbaceous plant., Feeds on detritus and plankton., , 3. Echinus, (Sea urchin), , l, , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 106, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 15, , Chordates, l, , l, l, l, , Phylum chordata was created by Balfour in 1880., This refers to the presence of a stiff supporting rod, like structures along the back (called notochord)., Chordata is the most heterogenous group of animals., Chordata includes humans and other vertebrates., However, not all chordates are vertebrates., All chordates have the following features at some, point in their life (in case of humans and many, other vertebrates, these features may only be present, in the embryo). These are the most distinct features, of chordates :, , –, , –, –, , Pharyngeal slits A series of openings that, connect the inside of the throat to the outside, of the “neck”. These are often, but not always,, used as gills., Dorsal nerve cord A bundle of nerve fibres, which runs down the “back”. It connects the, brain with the lateral muscles and other organs., Notochord The first skeleton laid during the, embryonic stage. Notochord is a cartilaginous, rod running underneath, and supporting the, nerve cord., , Chordata, Divided into two major groups, , Acraniata, Lower chordates, without brain box/cranium,, jaws and brain, , Craniata (Euchordata), Higher chordates, with brain box/cranium,, jaws and brain, , Includes, , Include single subphylum vertebrata, Notochord replaced by vertebral column, , Protochordates, Nonvertebrates or invertebrate chordate, , Divided into two division, , Divided into three subphyla, , Hemichordata Urochordata Cephalochordata, , Ostracodermi, , Cyclostomata, , Placodermi, , Agnatha, Divided into two classes, , Pisces*, Divided into three classes, , Tetrapoda, Divided into four classes, , Chondrichthyes Osteichthyes Amphibia* Reptiles, , *Anamniotes (absence of extra–embryonic membrane), , Gnathostomata, Divided into two, super classes, , Aves Mammalia, , Amniotes (presence of extra–, embryonic membranes)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 107, , ►ĺŐŕęďŚĚř, , Postanal tail An extension of the body part,, the anal opening., All chordates are deuterostomes, i.e, the anus, develops before the mouth in early embryonic, stages., In adult vertebrates notochord is replaced by, cranium and vertebral column and gives viability, of movement. In mammals the notochord is, represented as vestigial swellings called nuclei, pulposi in the vertebral column., Pharyngeal gill slits is functional throughout life, in protochordates and lower aquatic vertebrates, (fishes) but in higher vertebrates it is modified in, the adult with the acquisition of pulmonary, respiration., Other characteristics shared by chordates, include the following :, –, Bilateral symmetry, –, Segmented body, including segmented, muscles, –, Three germ layers and a welldeveloped, coelom., –, Single, dorsal, hollow nerve cord, usually with, an enlarged anterior end (brain), –, Tail projecting beyond (posterior to) the anus, at some stage of development, , –, l, , l, , l, , l, , –, , l, , Pharyngeal pouches present at some stage of, development, –, Ventral heart, with dorsal and ventral blood, vessels and a closed blood system, –, Complete digestive system, –, Bony or cartilaginous endoskeleton usually, present., Chordata is divided into two major groups –, acraniata and craniata. Acraniata is without brain, box and craniata is with brain box. (See Flow chart, on page no. 106)., , PROTOCHORDATES, l, , l, l, l, , Protochordates are chordates lacking head,, vertebral column, brainbox (cranium), jaws and, brain. About 2000 species are known to exit., Due to absence of cranium, protochordates are also, called acraniates., Another term of protochordates is prevertebrates., Protochordata can be divided into three subphyla –, hemichordata,urochordata and cephalochordata., , Hemichordata, l, , Hemichordates are small groups of marine, solitary, or colonial, wormlike enterocoelous animals,, most of which live in tubes (thus, they are also, known as tube dwellers)., , Protochordates, , Divided into three subphyla on the basis of location of notochord, Hemichordata, – Exclusively marine, worm like animals, – Notochord (called stomochord), found in the roof of buccal cavity, – Due to the absence of true, notochord, it is treated as, independent invertebrate, phylum by Hyman (1959) and, Van den Horst (1939), – Considered to be connecting link, between echinoderms and chordates, because of the resemblance between the, tornaria larva (of Balanoglossus) and bipinnaria, and dipleurula larva of echinoderms., – Classes, Enteropneusta. Eg. Balanoglossus, , Pterobranchia. Eg. Rhabdopleura, , Urochordata, – Commonly called tunicates, – Notochord (restricted to tail), & nerve cord only in larval stage, – Adult sac like, often sessile, contained in secreted tunic, – Hermaphrodites, retrogressive, metamorphosis, – Classes, Ascidaceae., Eg. Herdmania, Ciona, , Thaliaceae., Eg. Salpa, Pyrosoma, Larvaceae., Eg. Oikopleura, , Cephalochordata, – Notochord & nerve cord, present throughout life, along the entire length, – Only protochordate, with all basic, chordate structures, – Class : Leptocardii., Eg.Branchiostoma, (=Amphioxus)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 108, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , The body and enterocoelous coelom are divisible, into three unequal regions – proboscis, collar and, trunk.Tail is absent., In most forms, one to several pairs of gill clefts, lead from the pharynx to the exterior., They have no bony tissue (true notochord is, absent), but a buccal diverticulum is present in, preoral region, which is often regarded as, stomochord., Development is direct in some (eg Saccoglossus, Kowalevskii), while in others, it is indirect (eg B., clavigerus) via tornaria larva., The full grown tornaria larva is usually ovoid, in shape and is excessively transparent. The size, of tornaria larva varies from below 1 mm to 9, mm. It is provided with two ciliated bands. At, its anterior side, it has apical plate which bears, a pair of eye spots., , l, , l, l, l, , l, l, , l, l, , l, l, l, l, l, , Balanoglossus, a unique representative of the, subphylum hemichordata, is a burrowing and, exclusively marine animal ranging in size from, about 2 cm to 50 cm., Balanoglossus is tubicolous living in U shaped, burrows excavated in the sandy bottom., The wall of the tube is lined with mucous, secreted, by the mucous gland of the animal., In Balanoglossus, there is no definite exoskeleton, but there are four stiff structures of a supporting, nature – buccal diverticulum, proboscis skeleton,, branchial skeleton and a pygochord., The proboscis forms the anterior part of the body, and is continued posteriorly into a proboscis stalk., The proboscis sits in the collar somewhat like an, acorn in its cup, a character that has given the name, “acorn worms” to the group., The collar lies posterior to the proboscis and anterior, to the trunk., The functional significance of the cavities and, water pores in the probosics and collar is related, with their burrowing habits., The trunk is the elongated posterior part of the body., Operculum, a posterior prolongation of collar is, present in some species of hemichordates., A pair of genital ridges or genital wings are present, in the region of branchial apertures., The coelom is enterocoelous having been formed, as outgrowths of the enteron., The respiratory organs are in the form of a large, , l, l, l, l, l, , l, l, , number (upto 700 pairs) of gill pouches which, open internally in the pharynx by gill pores., The respiratory organs collectively form branchial, apparatus., The Balanoglossus has a straight digestive tube, with mouth and anus at opposite sides., The blood vascular system of Balanoglossus is of, closed type., Nervous system is composed of network of nerve, fibrils which is very primitive in nature., In Balanoglossus,the sexes are separate and are, indistinguishable externally except in case of the, colour of the ripe gonads shown through the body, wall in the living animal., Sense organs are poorly developed having, numerous epidermal neurosensory cells., Balanoglossus has great power of regeneration., One broken piece of the animal can regenerate into, new individual., , Urochordata, l, , l, , l, l, , l, , l, l, , l, l, , l, l, , Urochordata includes a peculiar group of widely, distributed marine animals called a sea squirts or, ascidians and their allies., Urochordates are also known as tunicates as their, bodies are covered externally by a leathery, translucent test or tunic composed of tunicin., The main representative of this subphyla is, Herdmania., Except in Herdmania, urochordates possess cells, called vanadocytes. They can extract vanadium, from sea water., The body of Herdmania pallida is roughly oblong, in outline, narrower at its attached end (with the, substratum) than at its free end., At its free end, it is provided with two openings–, the branchial and atrial apertures., Herdmania is called sea squirt because it can, suddenly contract its body to squirt water, simultaneously or independently through its, branchial and atrial apertures., The average size of the adult is about 9.5 cm long,, 7 cm broad and 4 cm thick., There are two types of spicules found in the body, of Herdmania. They are microscleres and, megascleres., The body is divided into two parts – body proper, and foot., The foot is made entirely of test.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 109, , ►ĺŐŕęďŚĚř–, l, l, l, , l, , l, l, l, , l, l, l, l, , l, l, , l, , The intestine forms a wide loop within the body., Ciliary feeding takes place because of its, sedentary habit., Lying in the midventral floor of the pharynx, is an, endostyle. It is a groove with four longitudinal, rows of gland cells with ciliated cells between them., The blood of Herdmania contains a green pigment, vanadium which is considered to be a respiratory, pigment., In the adult, there is a brain or nerve ganglion which, is about 4 mm long., Peristaltic contraction occurs in the heart of, Herdmania., Different types of receptors are present in its body, such as photoreceptors (sensitive to light),, tangoreceptors (sensory to contact), rheoreceptors, (sensory to water current) and thermoreceptors, (sensitive to temperature)., Nephrocyte cells in the body of Herdmania have, excretory function., The animal is hermaphrodite – there are two large, gonads., Herdmania is protogynous i.e., the ovaries mature, much before the maturation of testes., Development is indirect through ascidian tadpole, larva., The ascidian tadpole is tailed larva hatches from, the egg and becomes free swimming. It has an, oval body and a long laterally compressed tail. It, is called a tadpole larva because it somewhat, resembles a tadpole of a frog., The ascidian tadpole undergoes retrogressive, metamorphosis., The developmental process that transforms an, advanced larva of ascidians into primitive adult is, called retrogressive metamorphosis., Pyrosoma is a pelagic, free swimming colony which, probably emits the strongest light among marine, organisms. Possibly some symbiotic luminiscent, bacteria, found in photogenic mesodermal cell masses, present on the pharyngeal bands, produce light when, the zooids are disturbed even by rough sea waves., Kowalevsky (1866) discovered that the larvae of, the ascidians possess a welldeveloped dorsal, brain and spinal cord, a definite notochord and, lateral bands of muscles in the tail (i.e., organs, that are typical for the vertebrates). The ascidians,, therefore, considered as belonging to the same, phylum as the vertebrates, the phylum chordata., , l, , Botryllus is a colonial ascidian, widely distributed, in the Atlantic and the mediterranean. There is a, pair of hermaphrodite gonads., , Cephalochordata, l, l, l, l, , l, , l, , l, l, l, l, l, l, l, l, , Cephalochordata includes only two genera , Asymmetron and Branchiostoma (Amphioxus)., Amphioxus is now used as a common name of all, cephalochordates., Cephalochordates are small fishlike animals, showing the main chordate characters., Cephalochordata is the first group to have well, developed myotomes (muscle blocks) as body, musculature., The notochord extends the entire length of the, body projecting beyond the nervous system to the, tip of the snout., They have a dorsal, tubular neural tube or nerve, cord without a defined brain lying above the, notochord., Pharynx is large with numerous gillclefts opening, into an ectodermlined atrium., Wheel organ or Muller’s organ is present in the, oral head of Amphioxus., Wheel organ present in the vestibule is used for, producing a current of water., Metamerism is well marked, even the gonads are, segmental., There is a definite coelom., Excretory organs are segmental nephridia., Sexes are separate but males and females are alike, except for the gonads (testes or ovaries)., Development is indirect with a ciliated larva., , VERTEBRATA, l, l, l, l, l, l, , Vertebrata are advanced chordates and also known, as euchordates or higher vertebrates., Vertebrates have well developed cranium and, vertebral column., Notochord is embryonic, in adult it is replaced by, vertebral column., Vertebrates differs from tunicates and lancelets in, two important aspects vertebral column & head., Vertebrates originated during the ordovician, period., Vertebrates are divided into two superclass , agnatha and gnathostomata.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 110, , ŕďőĽę– ĐĽŐńŐĹť, , Agnatha, l, l, , l, l, l, l, , l, l, , l, , l, , l, , l, , l, l, l, l, , Agnatha (greek, “no jaws”) is a paraphyletic, superclass of jawless fish., In addition to the absence of jaws, agnatha are, characterised by absence of paired fins or limbs;, the presence of a notochord both in larvae and, adults; and seven or more paired gill, pouches. The branchial arches supporting the gill, pouches lies close to the body surface., The internal skeleton of agnathans is not bony, but cartilaginous., There is a light sensitive pineal eye (homologous, to the pineal gland in mammals)., There is no identifiable stomach., Fertilization is external and both ovaries and testes, are present in individual but gonads of only one, sex is functional in hagfishes, no larval stage;, separate sexes and a long larval stage in lampreys., The agnatha are ectothermic, and the heart contains, 2 chambers., The agnathans are the most primitive and ancient, of the vertebrates. Its fossils have been found, from the late Cambrian (about 500 million, years ago)., Agnatha is divided into extinct type , ostracoderms with exoskeleton and living type , cyclostomata without exoskeleton., Ostracoderms are oldest known vertebrate fossils, in the late cambrian and ordovician rocks dating, back to nearly 500 million years. They are the remote, ancestors of all the vertebrates including man., Their body form was fishlike, usually flattened, dorsoventrally, with a huge head and gill region,, a tapering but muscular trunk and some sort of tail, fin, eg. Cephalapsis., The cyclostomes (Gr. cyklos = circulation, stone =, mouth) are marine or freshwater vertebrates. Marine, forms ascend rivers for breeding. They may be, parasites or scavengers. There are only about 45, species in the class., Body is eel like but tail is compressed., Examples of cyclostomata are Petromyzon (or, lamprey) and Myxine (or hagfish)., Lampreys are parasitic species that use their, suckerlike mouths to attach to a fish host., Adult lampreys inhabit a saltwater marine, environment but swim up rivers to reach freshwater, breeding grounds (anadromous)., , l, , l, , l, , l, , l, , l, , Lampreys breed only once in their lifetime, in a, single tremendous reproductive bout, and die soon, after., Lampreys pass through an immature larval stage, before metamorphosing into adults. The larval, lamprey is always in freshwater., The larva is of particular interest to biologists who, study vertebrate evolution because it shares many, features with the cephalochordate Branchiostoma, (formerly called Amphioxus), which is the group, believed to be most closely related to the vertebrates., The resemblance between Branchiostoma and the, larval form of a very primitive vertebrate is striking,, and supports the closeness of the relationship, between the two groups., Petromyzon is rather unpleasent animals. Its life, cycle includes two quite different phases. The larval, phase (called ammonocoete) is a fresh water, sedentary, filter feeding and microphagus creature, reminiscent of the lancelet. The fish like adult, lives in the sea & is parasitic on fishes., Hagfish (also called slime eel because large mucous, gland opens along the sides of body and secretes, enormous quantity of slime) are scavenger species, that feed off dead and wounded organisms in the, ocean. They are also wellknown for their defence, mechanism; when threatened, hagfish ooze out, great amounts of foul slime., Evidence from the fossil record suggests that, agnathans reached their peak of diversity between, about 500 million and 340 million years ago. During, this period, they were plentiful both in the seas, and in freshwater habitats., , Gnathostomata, l, , l, , l, , l, , The gnathostomata (or gnathostomes) are the, majority of the middle devonian (–380 million years, ago) to recent vertebrates., They differ from all other craniates or vertebrates, in having a vertically biting device, the jaws,, which consists of an endoskeletal mandibular arch, and a variety of exoskeletal grasping, crushing or, shearing organs i.e., the teeth and jaw bones., The gnathostomata is divided into one extinct class, – placodermi and six living classes –, chondrichthyes, osteichthyes, amphibia, reptilia,, aves and mammalia., The first three classes include the fishes, and are
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 111, , ►ĺŐŕęďŚĚř, , often combined together as the superclass pisces., They have paired appendages in the form of fins., The remaining four classes are grouped together, as the superclass tetrapoda. They have paired, appendages in the form of limbs., The fishes and amphibians lack embryonic, membranes and are collectively called anamniota, or anamnia., The reptiles, birds and mammals develop special, embryonic membranes (amnion, chorion, allantois,, yolk sac) in their embryo for protection, nutrition, and gas exchange as an adaptation to terrestrial life., They are combined together as amnia or amniota., , l, , l, , l, , l, , l, , Placodermi were freshwater bony fishes having, a protective armour of bony scales and plates around, the body., The chondrichthyes are characterized by a, special type of hard tissue lining the cartilages, of the endoskeleton, the prismatic calcified, cartilage., The osteichthyes are characterized by endochondral, (spongy) bone in the endoskeleton, dermal fin rays, made up by lepidotrichiae (modified, tileshaped, scales) and three pairs of toothbearing dermal, bones lining the jaws (dentary, premaxillary and, maxillary)., , Table : Differences between pisces and tetrapoda, Pisces, , Tetrapoda, , 1., , Have an exoskeleton of dermal scales., , 2., , 4., 5., 6., , Have paired appendages in the form of pectoral, and pelvic fins., Have 2chambered heart (1 auricle, 1 ventricle), except in lung fishes., Lack internal nares in most cases., Breath with gills., Have internal ear only., , 7., , They are exclusively aquatic., , 8., , Lateral line sense organs are well developed., , 9., 10., 11., , All are poikilothermic., Have 10 pairs of cranial nerves., Tongue is nonmuscular and nonprotrusible., , Have an exoskeleton of epidermal scales, feathers, or hair., Have paired appendages in the form of pentadactyl, (5digited) limbs., Have 3 or 4chambered heart (2 auricles, 1 or 2, ventricles)., Have internal nares to help in air breathing., Breath with lungs, except some amphibians., Have external and middle ear, besides internal ear,, in most cases., They are typically terrestrial, some have secondarily, become aquatic., Lateral line sense organs are absents, except a few, larval amphibians., Some poikilothermic, others homoeothermic., Have 10 or 12 pairs of cranial nerves., Tongue is usually muscular and protrusible., , 3., , PISCES, l, l, l, l, , l, l, , Pisces is the first true jawed vertebrate group., The science that deals with fishes is called, ichthyology., Devonian is the golden age of fishes., There are about 30,000 to 40,000 species of fishes, differing widely from each other in shape, size,, habit and habitat., Members of the superclass pisces are primarily, aquatic in habitat., Skin is usually provided with scales. Common, , l, l, l, , types of scales are plac oid (present in, elasmobranchii fishes), cycloid (present in lung, fishes, holosteans and teleosteans), ctenoid, (present in modern higher teleosteans), cosmoid, (present in extinct lung fish and in living fish, Latimeria) and ganoid scale (characteristics of, chondrosteans)., Endoskeleton is cartilaginous or bony., Muscles are arranged in myotomes., Pisces are poikilothermal or cold blooded i.e. their, body temperature fluctuates considerably with that, of their environment.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 112, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Locomotion occurs with the help of fins., , l, , Types of Fins, , Unpaired, Median fins, , l, , Paired, Lateral fins, , Anal Caudal Pectoral, 1 or 2, dorsal fin fin, fin, fin, , l, , Pelvic, fin, , l, l, , Diphycercal, e.g., Cyclostomes, l, , l, , l, l, , l, l, l, l, , Heterocercal, e.g., Acipenser, , Homocercal, e.g., Polypterus, , Respiration is branchial (by gills), borne by the, gill arches. They open outside by gills slits. Gill, slits are 57 pairs, naked or covered with an, operculum (in teleostomi or bony fishes)., Accessory respiratory organ, called swim, bladder (or air bladder) is usually present. It arises, as a diverticulum from the pharynx or, oesophagus in bony fishes., Swim bladder is absent in cartilaginous fishes., The primary function of swim bladder is, respiration (in ganoid and lung fishes) and other, functions are buoyancy & sound protection (to, startle the enemies or to attract mates)., Heart is two chambered (one auricle + one ventricle)., The heart pumps only venous blood, therefore, called venous heart., Kidneys are mesonephric, sometimes, opisthonephric (in cartilaginous)., Both renal and hepatic portal systems are, present., , l, , l, , l, l, l, l, l, , l, l, , RBCs are nucleated., Vertebrae are amphicoelous i.e. biconcave on both, the sides., They possess lateral line sense organ which detect, vibrations (rheoreceptors) and electric fields, generated by other organisms., Lateral line system is innervated by VIII, IX &, X cranial nerves., Pit organs (in all fishes) and ampullae of lorenzini, (in elasmobranchs, probably thermoreceptors) are, other sense organs of lateral line system., The ampulla of lorenzini are found in the clusters, on the dorsal & ventral surfaces of the head, embedded below the skin., These are small vesicles and pores that form a, complex and extensive sensory system & detect, weak electrical fields at short ranges. It may also, detect temperature, salinity, changes in water, pressure, mechanical stimuli & magnetic field., Tail is muscular and helps in propulsion., Eyes are without lids., Internal ears are present and it is used for, balancing., Sexes are always separate., Development does not involve the formation of, extra embryonic membrane, thus, they are, included in anamniota., Young ones of fishes are called hatchlings,, fingerlings and fries., Pisces is divided into three classes placodermi,, chondrichthyes (cartilaginous fishes) and, osteichthyes (bony fishes)., , Pisces, Divided into 3 classes, , l, l, l, l, , l, , Placodermi, Earliest gnathostome, Extinct fishes, Notochord persist throughout, life, These placoderm fishes first, evolved into bony fishes and, later elasmobranchs, Only class of jawed, vertebrates to become, completely extinct (e.g.,, Climatius), , l, l, l, , l, l, , Chondrichthyes, (Cartilaginous fishes), Mostly marine, Notochord persists in adult, Include all members of sharks, (scoliodon, Rhincodon,, Carcharodon), skates, rays, (Torpedo, Trygon etc.), Truely chondrichthyes fishes, are called elasmobranch, With operculum called, holocephali (e.g., Chimareae ), , l, , l, l, , Osteichthyes (Bony fish), Includes all members of, lung fishes, ray finned &, lobe finned fishes, Bony fishes are also, called teleosts, Swim bladder present to, regulate buoyancy
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ĺŐŕęďŚĚř–, l, , l, , l, , l, , l, l, , l, l, l, , l, l, l, l, l, l, l, l, , l, l, , The name placoderm refers to the heavy armoured, bony plates that completely covered the head and, the thorax of these curious prehistoric fish., Along with acanthodi, placoderm is the only class, of jawed vertebrates to become completely extinct, that flourish during the devonian period., Chondrichthyes (also called cartilaginous fishes), includes all members of the shark (scoliodon,, Rhincodon etc.), skates, rays and chimareae., Chimareae (rabbit fish) is a connecting link, between cartilaginous and bony fishes., Anatomically it appears as an odd mixture of shark, like and bony fish like features. Instead of a toothed, mouth, their jaw bear large flat plates. The upper, jaw is completely fused to cranium which is very, unusual in fish. They eat seawood, molluscs,, echinoderms, crustaceans and other small fish. It, includes rat fishes, ghost fishes, lungs of herrings etc., Chondrichthyes are ureotelic (main nitrogenous, product is urea)., Osteichthyes (also called bony fishes) includes, all members of lung fishes, the ray finned & lobe, finned fish., The exoskeleton of osteichthyes or bony fishes is, formed of cycloid or ganoid or ctenoid scales., Tail fin is homocercal or diphycercal in bony fish., A swim bladder is usually present and acts as, hydrostatic organ, so these can stay at a particular, depth without expending energy in swimming., Two accessory heart chambers – sinus venosus, and conus arteriosus are present., There are 10 pairs of cranial nerves., Cerebellum and olfactory lobes are relatively, smaller in size than the cartilage fishes., These are ammonotelic (main nitrogenous waste, is ammonia)., Claspers are never present in osteichthyes., Bony fishes are also called teleosts., Dipnoi (also called lung fishes) belongs to subclass, sarcopterygii of class osteichthyes., There are three living genera of lung fishes , Neoceratodus in Australia, Lepidosiren in South, America and Protopterus in Africa., Lobefinned lung fishes are believed to be fore, runners of tetrapods., During unfavourable condition Protopterus, undergoes summer sleep (aestivation) and burrows, into the soil to a depth of about 2 feet., , l, , l, l, , l, , l, l, l, , l, , l, l, l, , l, l, , 113, , Lung fishes are double breathers. They respire, through gills as well as lungs (modified structure, formed by vascularization of swim bladder)., Lung fish shows cannibalism i.e. it eats the flesh, of its own kind., Lung fishes have well developed lateral line sense, organ specially on head. Development in lung, fish includes metamorphosis., Fish as a group pay little parental care to their, eggs and gonads. This lack of parental behaviour, is correlated with production of great numbers of, eggs and sperms., Fishes which live within a narrow range of, salinity are called stenohaline., Fishes that can tolerate wide variation in salinity, are termed as euryhaline., Movement of fish from fresh water to salt water, (sea) for spawning is called catadromous, migration (e.g. Anguilla)., The reverse movement, i.e from salt water to, fresh water is termed as anadromous migration, (e.g. salmon, shark etc.), Stone fish (Synanceja verrucora) is a highly, poisonous fish., Pygmy goby (Pandaka pygmaea) is the smallest, fish, size – 7.5 to 9.9 mm., Dwarf sea horse (Hippocampus zosterae) is, the slowest fish having a speed of 0.016 km or, 15 mt/hr., Sail fish (Istiphorus platypterus) is the fastest fish,, having a speed of 109 km/hr., Economics importance of fishes are –, –, As food, r, Fresh water species : Labeo rohita, (rohu), Labeo calbasu (calbasu), Catla, (catla), Cirrhina mrigala (mrigal),, Wallagonia attu (malhi), Cyprinus carpio, (common carp), Mystus seenghala, (singhala), Ophiocephalus (snake head)., r, Marine species : Harpodon (bombay duck),, Anguilla (eel), Stromateus (pomphret),, Sardinella (salmon), Hilsa (hilsa),, Exocoetus (flying fish), Solea (flat fish)., r, Catfishes : Mystus seenghala (singhala),, Clarius batrachus (magur), Heteropneustus, (singhi) and Wallagonia attu (malhi)., –, Products of commercial value : Fish oil, fish, meal, liquid glue. Cod liver oil is rich source
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 114, , ŕďőĽę– ĐĽŐńŐĹť, , Scientific name, l, , 1., , Table : Important examples of pisces, Important notes, , Cartilaginous fishes, Sharks : Body is laterally compressed and spindle like. Inhabits open water and swim actively by lateral, undulation of body., Fast swimming carnivorous fish. It is edible, its skin is used as an, Scoliodon (Dog fish), abrasive (shagreen) and its liver yields oil., Exoskeleton is formed of dermal placoid scales., Tail fin is mostly heterocercal (2 unequal lobes)., Teeth are acrodont (directly attached to jaw bone)., There is a scroll valve in the intestine., Males have claspers (copulatory organs) between the pelvic fins., Rhincodon (Whale shark), , Second largest vertebrate (1517 mt and weight 39.5 tonnes). Largest fish., , 5., , Trygon, (Sting ray), , Whiplike tail, modified into stinging organ, armed with saw edged, spines or stinger with venom glands. There wounds are very painful, and heal very slowly., , 6., , Latimeria, , Living fish, resemble lung fishes in having internal nares, lobed fins, and lung or air sac., Living fossil. Connecting link between fishes and amphibians., Bony fishes, , 7., , Salmo (Salmon), , Anadromous, , 8., , Anguilla (Eel), , 9., , Muraena (Spotted eel), , Larva is “Glass Fish” or leptocephali, catadromous. The young eel, back to fresh water. It is known as elver., Largest eel. At times it attacks even human beings also., , 2., , Man eater shark., Carcharodon (White shark), l, Rays : Includes skates, electric rays etc. All are bottom dwellers and sluggish, swim by flapping pectoral fins., Carnivorous fish, have a pair of electric organ (formed from, 4. Torpedo, metamorphosed (branchial) muscles for defence and predation., (Electric ray), 3., , 10. Exocoetus (Flying fish), 11. Anabas (Climbing perch), , So called because it glides for few metres in air by large pectoral fins., Can live outside water for several days. Unable to climb trees, birds, may pick it up from land and drop on trees., , 12. Echeneis, (Remora/sucker fish), , Sucker represents modified anterior dorsal fins. Feeds on the left over, of shark’s prey. The relationship is that of commensalism or, ectocommensalism., , 13. Hippocampus, (Sea horse), , On the belly of male is a brood pouch for incubating eggs. Sometimes, referred as pregnant males. Shows parental care. Dried skin used for, the preparation of ornaments., , 14. Labeo rohita [Rohu (carp)], , Carnivorous when young, but become herbivorous when adult, oviparous., Carnivorous, used as larvicidal (feeds on larvae),, Effectively used against malaria as Anopheles is the vector of malaria., 1. Other examples of cartilaginous fishes are Stegostoma (Zebra shark), Rhinobatus (guitar fish), Pristis (Saw fishes)., 2. Other examples of bony fishes are Tetradon (globe fish); Diodon (porcupine fish); Syngnathus (pipe fish);, Carassius (gold fish); Oncorhynchus (pacific salmon); Solea (flat fish); Clarius (cat fish or mangri in hindi)., 15. Gambusia, (Mosquito fish, Top minnow)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ĺŐŕęďŚĚř, , –, –, –, –, –, , –, , of vitamin A and D (extracted from cod and, shark). Fish meal used as fertilizer and poultry, feed., Malaria control : Gambusia feeds on mosquito, larvae., Leather : Shark skin provides leather., Pituitary extract of shark is used for medical, purpose., Shagreen is a rough skin of sharks used for, polishing., Isinglass is a white, transparent, almost pure, gelatin obtained from swim bladders of some, fresh water fishes for making jellies, glue, etc., Fish guano : After extraction of oil the meat, of fishes is dried. It is fish guano and used as, poultry feed., , l, l, , l, l, l, , Table : False fishes, Jelly Fish, Shell Fish, , – Aurelia (coelenterate), – (a) Oyster and other molluscs, (b) Lobster, and, other, crustaceans., Razor Fish – Used both for a true fish, Xyrichythyes species as well as, Solen, a bivalve., Silver Fish – Lepisma (an insect)., Cuttle Fish – Sepia, a mollusc., Devil Fish – Octopus (a mollusc)., Hag Fish, – Myxine (cyclostomata)., Star Fish, – Asterias (echinoderm)., Whale Fish – Whale (aquatic mammal)., , AMPHIBIA, l, l, l, l, , l, l, l, , The vertebrates to come out of water for the first, time are amphibians., Amphibians are the first animals to attempt, transition from aquatic to terrestrial life., Amphibians are the animals who can live on land, as well as in water., Amphibians evolved during devonian period from, osteolepid fishes and dominated during, carboniferous period., The splitting of one phyletic lineage into two or, more lines is termed cladogenesis., Primitive amphibians like Ichthyostega, Eryops, closely resemble the lung fishes., All amphibians are fresh water except Rana, concrinora (frog)., , l, l, l, l, l, l, l, l, l, l, l, l, l, l, l, l, , 115, , They are poikilothermic (cold blooded) i.e., ectothermal animals., These are earliest and the most primitive tetrapods, with two pairs of limbs. Each limb is pentadactyl, in nature., Limbs are totally absent in caecilians., Fore limbs and hind limbs are unequal in size in, anura but similar in size in urodeles., Skin is slimy, moist, glandular as exoskeleton is, absent., Glands in amphibia, Mucous gland, Poison gland, Larger in size,, Smaller, flask shaped, distributed less, glands found over the, evenly., entire surface of the, body., Secrete colourless, Secrete mild poison, watery fluid, mucous., It keeps the skin moist, Protect the animal in, some degrees from, glistening and sticky., enemies. E.g toad, E.g. frog., Scales are present in some cases of apoda, e.g., Ureotyphlus., Endoskeleton is bony. Skull is dicondylic., Vertebrae are procoelous and amphicoelous., Ribs are usually absent. Even, if the ribs are, present, they do not reach the sternum., Sternum makes its appearance for the first time, in amphibians., Tympanum is found in frogs and toads. It is, absent in urodeles and caecilians., Respiration is effected by skin, buccal cavity, lungs, and gills (Gills are found in some adult urodeles)., Only respiratory organs during larval stage are, gills., Both hepatic and renal portal sytems are present., R.B.Cs are oval, biconvex and nucleated., Teeth are present in both the jaws., Vomerine teeth are present., Hinds limbs are vestigal in Siren (mud eel)., Vocal cords are present. Anurans are the earliest, vocal vertebrates., Radius and ulna are fused into radioulna. Tibia, and fibula are fused into tibiofibula in anura., Bidder’s organ is attached to the interior part, of kidney in toads. The removal of testis from, males leads to the development of ovaries from, Bidder’s organs.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 116, , l, l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Ductus Botalli connect systemic and pulmonary, arch on each side., Heart is 3 chambered. Accessory chambers are, sinus venosus and truncus arterious., Amphibians are carnivorous., In adult functional kidney is mesonephric type., Nitrogenous end product is urea., In front of each testis are several finger like, processes called fat bodies or corpora adiposa., Nervous system includes central nervous system,, peripheral nervous system and autonomic, nervous system., External receptors, (Receive impulses from the environment), , l, l, l, , l, l, l, l, l, l, l, , Tangoreceptor Gustatoreceptor, Statoacoustic, (Organ, (Organ, receptors, of touch), of taste), (Organ of hearing, and balance), Olfactoreceptor Photoreceptor, (Organ of smell) (Organ of sight), l, , l, , Eggs are mesolecithal and telolecithal., Cleavage is holoblastic and unequal., Development is indirect which includes a larval, stage and metamorphosis., Metamorphosis in amphibians is controlled by, thyroxine., , l, , l, l, , Extraembryonic membranes are absent, (amniotes)., Fertilization is usually external, but it is internal, in caecilians and urodela., Some amphibians exhibit neoteny or paedogenesis, e.g. Axolotl larva of Ambystoma., Tadpole larva is connecting link between fishes, and amphibians., Largest frog is Rana goliath., Largest amphibian is Cryptobranches, alleganiensis., Amphibia having largest gestation period is, Salamandra atra (36 months)., In winter, Salamander goes to winter sleep or, hibernation and in summer, summer sleep or, aestivation., Amphibia are divided into extinct and living types., Extinct amphibians were crocodile and, Salamander like with pentadactyly limbs. Eg., Eryops, Branchiosaurs etc. While living amphians, are divided into apoda/gymnophiona, urodela/, caudata, anura/salientia., All the living amphibians belongs to subclass,, lissamphibia., Extinct amphibians belongs to stegocephalia., , Amphibia (Living), 3 subclasses, , Apoda/Gymnophiona/Caecilians, (Limbless amphibians), l Limbs and tail absent., l Long wormlike (body is eel like),, burrowing (snake like because, they are burrowers, the eyes are, replaced by specialised sensory, tentacles on the snout. Very rarely, seen due to their burrowing, nature)., l Copulatory organs present., E.g. Ichthyophis (Blind worm),, Ureotyphlus., , l, , l, , l, l, , Urodela/Caudata, (Tailed amphibians), Body with head, trunk and tail., Limbs of equal size., Commonly called newts and, Salamanders., Possess largest RBC., Males are without copulatory, organ, Two orders, , l, , l, l, l, , l, , l, , Anura/Salientia, (Tailless amphibians), Body with head and trunk. Tail, absent, Forelimbs shorter than hindlimbs., Respiration by lungs, Commonly includes frogs and, toads, Vocal cords develops for the first, time, Order Phaneroglossa, Eg. Rana, Bufo, Hyla (tree frog)., Rhacophorus (flying frog) etc., , Caducibranchiata, Eg. Salamandra, Ambystoma, Triton
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ĺŐŕęďŚĚř, , 117, , 5., , Table : Important examples of amphibians, Important Notes, Apoda (Limbless amphibians), Male copulates female by protrusible cloaca and fertilization is, Ichthyophis, internal. They hatch into tadpoles., (Blind worm), Urodela (Tailed amphibians), Completely aquatic, represent a permanent neotenic larval stage., Necturus (Mud puppy or water dog), (i.e. larva is capable to reproduce again). This happens due to lack, of iodine in water which causes deficiency of thyroxine hormone., Shows both neoteny and paedogenesis. Larva is called axolotl in which, Ambystoma (Tiger salamander), metamorphosis is induced by injecting thyroxine (thyroid extract), Terrestrial, viviparous, Salamandra maculosa, (Spotted or firesalamander), Carnivorous, permanent neotenic form showing almost no adult character., Siren lacertina (Mud eel), , 6., , Amphiuma (Congo eel), , Scientific Name, , 1., 2., 3., 4., , 7., , 8., 9., 10., 11., 12., 13., 14., 15., , 16., , Anura (Tailless amphibians), · Semilarval form of Salamandra derivation., · Has largest erythrocyte of any animals., Triton (European salamandra), · Exhibit sexual dimorphism., · Male possesses a dorsal median crest., · Fore and hindlimbs are well developed., · Scales are entirely absent., Proteus (Olm or European blind cave It is a neotenic and a permanent larva with three pairs of branching, Salamandra), red coloured external gills and two part of open gill clefts., Alytes obstetricans (Midwife toad), Males shows parental care by entangling eggs around their hindlegs., The toxins in its skin induce vomiting so that predators avoids it in, Bombinator or Discoglossus Igneus, future, (Fire Bellied toad), The male presses fertilized eggs on female’s back so that each sinks, Pipa pipa (Surinam toad), into a little pocket. Here they develop directly into young toads. Feet, possess large webs., · Green in colour, adapted for life on trees., Hyla, · Has adhesive pads on the digits for climbing tree., [Arboreal frog (Green tree frog)], · Shows mimicry., Webs and flattened body serve as a parachute in gliding from a higher, Rhacophorus (Polypedates), elevation to a lower one., (Flying frog), Male has extensive vascular filamentous or hair like cutaneous, Astylosternus (African hairy frog), papillae on flanks and thigh (respiratory)., Rana tigrina, · Undergoes aestivation (summer sleep) and hibernation (winter sleep)., (Common Indian frog or Indian bull frog) · Moulting and colour changes (called metachromasis) are well, marked., [For more details refer chapter, · Larva of frog called tadpole, undergoes metamorphosis to, Morphology & Anatomy of Animals], become adult., · Males have vocal sacs and nuptial pad (used during amplexus, which occur in water = false copulation)., Bufo melanostictus (Indian toad), · Visits water only for breeding., · Mouth does not contain teeth, · Secretions of its skin gland [bufotenin (C12H16N2O), bufotoxin, (C34H46O10) and bufonin (C34H54O2)] probably have the healing, property.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 118, , ŕďőĽę– ĐĽŐńŐĹť, , REPTILES, l, l, , l, , l, l, l, l, l, , l, l, l, l, l, l, l, l, l, l, l, , l, , l, , Reptiles are the first true land vertebrates., The study of reptiles, lizards and snakes is called, herpatology, saurology and ophiology (or, serpentology) respectively., Reason behind the adaptation of reptiles on land, life are horny scales which check loss of water,, internal fertilization as gametes cannot survive, on land, shell around the egg to check dessication,, fluid filled amnion around the embryo to provide, aquatic environment for development on land., Reptiles evolved from labyrinthodont, amphibians., Reptiles were dominant in mesozoic era but not, appeared in palaeozoic era., Mesozoic era is known as the golden age of, reptiles or golden age of dinosaurs., Reptiles are cold blooded vertebrates i.e.,, poikilothermous., Reptiles are lung breathing animals. Respiration, by lungs, no gills, cloaca used for respiration in, some spp (e.g., turtle), respiration through skin, during embryo development., Integument covering the body is dry, horny and, scaly. Skin is epidermal in origin., In some reptiles the skin is covered with hard plates, called scutes., Reptiles are tetrapods. Hind limbs and fore limbs, are pentadactylous and provided with claws., The body is bilateral symmetrical & divided into, head, neck, trunk and tail., Skull bears temporal fossae., Skull is monocondylic, articulated with the, vertebral column by a single occipital condyle., Vertebral column is divided into cervical, thoracic,, lumbar, sacral and caudal regions., Tongue is protrusible. It is bifid in snakes., Alimentary canal opens in cloaca., Vertebrae in reptiles are procoelous and, amphicoelous., Heart is three chambered with two auricles and, one ventricle (except, crocodile, alligator and, gavialis where heart is four chambered)., Kidney metanephric, excretion uricotelic, cranial, nerves 12 pairs (except snake as they have 10, pairs of cranial nerves)., Sexes are separate usually with a muscular, , l, l, l, l, l, , l, l, l, l, l, l, l, l, l, l, , l, , l, l, l, l, l, l, , copulatory organ., Fertilization is internal. There is no, metamorphosis., Development is direct and cleavage is meroblastic., Parental care usually absent., Femoral glands are secretory glands in the femoral, region of reptiles, giving them characteristic smell., Foramen of Panizzae is an aperture in the heart, of lizards and crocodiles. It is located at the point, where right and left aorta cross each other and, are in contact., Snake has both an exoskeleton and endoskeleton., Limbs are absent in snakes., Paddle like limbs are found in turtles., Tibia and fibula in the hind limbs and radius and, ulna in the forelimbs are separate., R.B.Cs are oval, biconvex and nucleated., Sternum is well developed, but absent in, chelonians and snakes., Most of the reptiles are oviparous. Few of them, like sea snakes and vipers are viviparous., Eggs are macrolecithal covered with calcarious, shell (cleidoic)., Reptiles are classified into two subclasses , anapsida and diapsida., Extinct reptiles are dominant from the triassic, to the cretaceous periods of mesozoic era. These, reptiles were mostly terrestrial with tetrapod, locomotion., Seymouria, lizard like, is the most primitive and, intermediate connecting link between amphibia, and reptile., Ichthyosauria is fish like reptile found in triassic, and jurassic period., Dimnetrodon is mammal like reptile found in, carboniferous and permian period., Dinosaurs (means terrible lizard) are large and, extinct reptiles., Dinosaur originated along with primitive mammals, during triassic period of mesozoic era., It becomes extinct during cretaceous period of, mesozoic era., Dinosaur belongs to archosauria branch., Archosauria divided into two orders saurischia, (means reptiles hips i.e., possess triradiate pelvis), and ornithischia (means birds hips, possess, tetraradiate pelvis).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 119, , ►ĺŐŕęďŚĚř–, , Reptiles, Subclasses, , Diapsida, (Extinct as well as living), Order, , Anapsida, (Primitive reptiles), Order, , Cotylosauria, e.g. Seymouria, (extinct), , Chelonia, e.g., Chelone, Testudo, , Extinct subclass, Parapsida (eg. Ichthyosaurus,, Protosaurus, Plegiosaurus, l Synapsida (eg. Dimnetrodon,, Cynognathrus), l, , Rhyncocephalia, Contain extinct, reptile except, Sphenodon, , l, l, l, , Squamata, Living reptiles, Procoelous vertebrae, Male possess paired, copulatory organs, (hemipenis), , Ophidia (snakes) e.g. Viper, l, , l, , l, , l, l, l, l, l, l, , Some important dinosaurs are –, –, Brontosaurs (thunder lizard) of jurassic period., –, Tyrannosaurs (tyrent lizard), largest dinosaurs, and largest flesh eater., –, Diploducus., –, Gigantosaurs (largest dinosaurs), –, Iguanodon (ornithischian dinosaurs), –, Stegosaurs (plated lizard), found in jurassic, period., –, Triceratopus (ornithischian dinosaur), Eyelids, lacrimal gland, urinary bladder,, sternum, episternum and vocal cord are the parts, which are absent in snakes., Each half of snake’s lower jaw is made of six bones,, articular, angular, subangular, coronoid,, dentary and splenial., Both the jaws bear teeth. These are acrodont,, pleurodont, homodont., Jacobson’s organs are the sense organs present on, the palate or upper jaws in ophidia., Males possess double penis., Eyes of snake are covered by transparent cuticle., Fangs are modified maxillary teeth., Poison glands are modified parotid salivary glands., , l, l, , l, , l, , l, l, l, l, , l, , Crocodilia, e.g. Crocodilus,, Gavialis, Alligator, etc., , Lacertilia (lizards) e.g. Varanus, , The poison of snakes is called venom., The poison contains proteolysins (poison of vipers), cardiotoxins (poison of cobra & few vipers),, haemotoxins in which venom react with blood, (found in vipers), neurotoxin in which poison, directly react with nervous system (cobra) and, antibactericidum., Vipers are poisonous, possess a characteristic, triangular head covered with small soles and, having a narrow neck., Loreal pit, a heat sensitive organ, is present, between the eye and nostril on either side., Loreal pit is the characteristic difference point, with true viper., Vipers are of two types pit viper (Rattle snake), and pitless viper (Russel’s viper)., Antivenom is used for the treatment of snake, bite., Antivenin’s are prepared by immunising horses, and mules against the various types of snake, poison., Haffkin Institute, Bombay and Central Research, Institute, Kasauli are known for Antivenom in, India.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 120, , ŕďőĽę– ĐĽŐńŐĹť, , Scientific Name, , Table : Important examples of reptiles, Important Notes, Rhyncocephalia, Also called Hatteria. ‘Living Fossil’, abundant during mesozoic, times. Resembles with lizard and crocodiles, have functional third, eye on the forehead, pentadactylus., Squamata, , 1., , Sphenodon punctatum, [Tuatara], , 2., , Hemidactylus, [House, Lizard/Wall, lizard/, Gecko], Draco, [Flying dragon/Flying lizard], , 3., 4., , Phrynosoma, [Horned toad], , Lizards, l Unlike most lizards, making clicking and peeping sounds., l Only one of gecko which lay round, hard shelled egg., l Can regenerate the lost tail, l Patagium used for gliding from tree to tree., l Gular pouch (below the thorax) is larger in male., l, , l, , 5., , Chameleon [Chamaeleon], , l, , l, , l, , 6., 7., , Heloderma (gila monster), [Beaded Lizard], Varanus (V. Komodoensis), [Monitor Lizard], , 8., , Ophiosaurs [Glass snakes], , 9., , Calotes versicolor, [Garden Lizard or Girgit], , 10. Uromastix hardwickii, [Spiny tailed lizard], Poisonous, 11. Naja naja, [Common Indian Cobra], 12. Ophiophagus hannah [King Cobra], 13. Bungarus caeruleus [Krait], Ø, , Have two enlarged horns on head give them formidable, appearance. Has remarkable protective adaptation., When irritated it shoots a gel of blood out of its eye which, frightens the enemy and provide it the chance of escape., Famous to change their body colours rapidly to blend with their, surroundings (camouflage)., Tongue are extremely protrusible spoon shaped sticky and capable, for capturing prey even at a distance of 20 cm., Oviparous lizard., , Only poisonous lizard in the world. Poison is neurotoxic., Eyes are fixed., l Largest living Lizard (L 2.5 m, W 100 kg), l Found in Malaya Archipelago., l Savage and carnivorous lizard., l It is capable of killing adult water buffallo, but it normally preys, upon wild pigs, goats, deer etc., l Limbless Lizard., l The limbless lizards can be differentiated from snakes by their, non expansible mouth, movable eyelids and ear openings., l Anguis Fragilis (slow/blind worm) is another limbless lizard., l Also known as blood sucker., l Have ability to change colour which is due to temperature and, environment., l Nonaggressive lizard., l Herbivorous, oviparous, diurnal., l Tail muscle is eaten by some tribal people., Snakes, l 2 mt. long, rake can dilate into hood bear spectacle mark dorsally., l Highly poisonous and have neurotoxic venom, oviparous., , l, , l, , l, l, , 5 mt. long, one of the largest deadliest venomous snakes., Highly poisonous land snake. Its poison is three times as, virulent as that of Cobra. Commonly found in hilly areas., contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ĺŐŕęďŚĚř–, , 14. Crotalus, [Pit viper (Rattle snake)], , l, , l, , l, , 15. Vipera russelli, [Russel’s viper (Pitless viper)], , l, l, l, l, l, , 16. Echis carinata [Saw sealed viper], , l, l, l, , 17. Hydrophis [Seasnake], , l, , l, l, , 121, , Rattle snake is recognized by a loose, horny rattle at the end of the, tail which is shaken vigrously to warn off intruders., Rattle is formed when the snakes skin is shed, the end section of, the rattle and attached ring of the old skin are retained on moulting., Feeds on small mammals and reptiles., Usually occurs in pairs., Terrestrial, nocturnal and carnivorous., Produces loud hissing sound., Poison is fatal to man., Upper surface of the body shows three rows of large black rings, appearing like chain so also known as chain viper or Dobia., A small desert viper (4025 cm), It is not fatal to man but can kill small domestic animals., Found in sandy place throughout the world., Pass their whole life in sea water and are highly poisonous and, about 20 times more than cobra., Have laterally compressed tail (suited for swimming)., All are ovoviparous., , Sea snakes have no gills and must rise to the surface for air, but they can remain underwater for several hours, obtaining, dissolved oxygen from water that they swallow and eject. They feed on elongate fishes, such as eels, which they paralyze with, their venom, but do not attack humans unless threatened., , NonPoisonous, 18. Dendrophis [Tree snake], , Ø, , l, l, , 19. Eryx johnii, [Double headed snake or Sand boa], 20. Python, , l, , l, l, l, l, , It is diurnal., Feeds on lizard and frogs., Tail (small, prehensile) bears a false resemblance to head, hence, the common name., Largest non poisonous snake., Commonly called ajgar and grow upto 6 meter., Indian python Python molurus, Python reticulatus of South Asia grow to over 10 meters., , Anaconda, common name for a large South American snake of the boa family. The anaconda or water boa is one of the largest, and most powerful snake in the world, and the largest in the western hemisphere. Average length is 20 ft. Average diameter, is 12m. Average weight is 330 lb. (148.5 kg.). It kills its prey by constriction, or squeezing. The reptile is found in the rivers, of the Guianas and Brazil., , 21. Typhlops braminus [Blind worm], , l, , Turtle and Tortoise, , l, l, l, , l, l, , l, , Insectivorous, look like earthworm, hence called worm snake., , Chelonia, l Ancient reptiles. Former is aquatic and latter is landforms, e.g., Chelone mydas (green turtle), Trionyx (tortoise or soft river, terrapin), Testudo (land tortoise)., , Other non poisonous snakes are, Uropeltus : Similar to blind snakes. Also called rough tailed snake., Ptyas (= Zamenis) : Most common Indian rat snake called ‘dhaman’., Tropidonotus : Common pond or grass snake (most common snake). Grass snake differ from most, water snakes in that they lay eggs instead of giving birth to living young., Lycodon: Wolf snake, mimics the poisonous Krait, but it is nonpoisonous., Dryophis : Whip snake.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 122, , l, l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Snakes can receive sound waves passing through, solid terrain only., Moulting or shedding of skin in snakes is done, by cornified cells., Of all the snakes only 33% of snakes are poisonous., The chief poisonous snakes of India are cobra,, king cobra, krait, vipers, sea snakes and coral, snakes., Sea snakes secrete mytotoxic venom and cause, muscular pain., , AVES, l, l, l, l, l, l, l, l, , l, , l, l, , l, l, l, , l, l, l, , l, l, , Study of birds is called ornithology., Birds are feathered bipeds, air breathing, truely, flying vertebrates., Oology is the study of birds nest., Phenology is the study of birds migration., Salim Ali, a famous ornithologist, was known as, bird man of India., Birds evolved in jurrasic period from, ornithischian dinosaurs., Modern birds appeared in cretaceous period., Huxley has called birds to be glorified reptiles, because Archaeopteryx represents a connecting link, between the organization of birds & reptiles., Archaeopteryx lithographica was discovered in, 1861 by Andreas Wanger from the lithographic, state of solenhofen in Bavaria of Germany., Birds are the only amniotes whose bodies are highly, specialized for aerial mode of life., Skin is dry and devoid of glands except the oil, or preen gland or uropygeal gland at the root of, the tail., Oil gland is absent in ostrich and parrot., They are warm blooded, oviparous, bipedal,, flying vertebrates with an exoskeleton of feathers., Forelimbs are modified as wings for flying and, variously adapted for walking, running,, scratching, perching etc., Hindlimbs are adapted for walking, perching or, swimming (bipedal locomotion)., They have well developed pectoral muscles for, flight., Pectoralis major, pectoralis minor,, coracobrachialis longus, tensor patagialis are the, flight muscles present in birds., Skull is smooth and monocondylic., Bones are light and pneumatic and have no marrow., , l, l, , l, l, l, , Both clavicles and single interclavicle fused to a V, shaped bone called furcula or wishbone., Furcula (also called merrythought bone) helps in, flying & keep both the wings well apart. It is, absent in flightless bird., Fused tail vertebrae form a structure called, pygostyle., Ribs are double headed with uncinate processes., Eyes are large and possess nictitating membranes,, sclerotic plates and a vascular pecten. Pecten is, present in flying birds., Reptilian characters of Archaeopteryx, –, The bones were solid and not pneumatic., –, Strong jaws with thecodont dentition., –, Presence of long tail with 18 20 free caudal, vertebrae., –, Presence of sclerotic ring., –, Centra of vertebra were probably, amphicoelous or biconcave (as in, Sphenodon)., –, Presence of abdominal ribs., –, Ribs are without uncinate process., –, There is no definite trace of sternum., –, Presence of elongated ilium and backwardly, directed pubis., –, Separate metacarpals. Carpometacarpus is, absent., –, Digits are clawed., –, Separate tibia and fibula., –, Hand bears a typical reptilian plan, phalanges, being 2,3 and 4 respectively in first, second, and third digits., Birds like characters of Archaeopteryx., –, Presence of feathers as body covering., –, Fore limbs modified into wings with only 3, digits., –, Presence of single occipital condyle., –, Fusion of skull bones., –, Both the jaws protrude to form beak., –, Presence of V shaped furcula., –, The scapulae are slender curved bones., –, The bones of limbs and girdle are eminently, bird like., –, The hind limb possesses a tarsometatarsus,, phalanges being 2,3,4, and 5 respectively in, each digit which terminates into a claw and, hallux is present directed backwards.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 123, , ►ĺŐŕęďŚĚř–, Aves, Subclasses, Archaeornithes, Ÿ Extinct jurassic birds, Ÿ Eg. Archaeopteryx lithographica, Neornithes, (Extinct as well as jurassic birds), Ÿ Wings usually well developed & adapted, Ÿ Teeth absent except in some fossil birds, , Divided into super orders, Odontognathae, Ÿ Extinct toothed cretaceous birds, eg. Hesperornis (flightless marine bird), and Ichthyornis (flying marine birds), Palaeognathe (Ratitae), Ÿ Flightless birds (i.e., walking or running birds), Ÿ Includes the largest of living birds, Ÿ Have vestigial or rudimentary wings & poorly developed pectoral muscles, Ÿ Oil gland is absent except in Tinamous [Tinamous have a keeled sternum and fly, (weakly)] and Kiwi, Ÿ Male has large penis, Ÿ Eg. Ostrich, Emu, Kiwi. Extinct ratites (probably as a result of human hunting) are, elephant bird of Madagascar and the moas of NewZealand, Impennae, Ÿ Flightless birds specialized for aquatic life (forelimbs are modified into flippers), eg. Penguins, Neognathae, Ÿ Modern flying birds, feathers with interlocking mechanism, Ÿ Beak and pygostyle is present, wing keeled sternum, Ÿ Grouped into atleast 6 homogenous ecological groups, – Arboreal birds (Eg. Sparrow, pigeon, kingcrow, bulbul etc.), – Terrestrial birds (Eg. Quail, cuckoo etc.), – Swimming and diving birds (Eg. Swans, kingfishers, duck etc.), – Short birds and Wading birds (Eg. Sandpiper, gull, curles etc.), – Aerial birds (Eg. Humming birds, goat sucker etc.), – Birds of prey (Eg. King vulture, kite, Tylopus etc.), l, l, , l, l, , l, , Pecten, a comb like structure, is well developed in, diurnal birds than nocturnal and absent in kiwi., Pecten helps in accomodation and nutrition of, eye ball, aids in perception of movements by, falling shadow of its own on retina forming small, blind spot & also regulates the pressure in fluid, in the eye., Heart is 4 chambered. Only right (systemic) aortic, arch persists in adult., Kidney is metanephric, excretory system is without, urinary bladder (exception Ostrich, Rhea). Renal, portal system is vestigial., Bursa fabricus is a lymphoid tissue attached to, , l, l, , l, , l, , cloaca of some young birds which takes part in, formation of lymphocytes. It is also called cloacal, thymus., Syrinx is the characteristic feature of birds which, is responsible for the sound production., Alimentary canal contains crop (modified, oesophagus) for storing and softening of food, and gizzard as grinding part of stomach., Respiration occurs by compact spongy, non, distensible lungs which is continuous with thin, walled sacs., Sexes separate and sexual dimorphism is well, marked.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 124, , l, l, , l, l, l, l, l, l, l, , l, l, , l, l, , l, l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Fertilization is internal., Only left ovary and oviduct are present which, provide an adaptation to avian mode of life. Loss, of an ovary and oviduct in pigeon reduce weight, which is an advantage in flight. Further, the, retention of a single ovary also helps in the safe, manipulation of large eggs with breakable shells., Eggs are macro and megalecithal with meroblastic, & discoidal cleavage., For feeding the young ones, both sexes secrete, pigeon milk from the crop., Olfactory sense is poorly developed in birds, (except kiwi, where it is highly developed)., Pseudopenis is present in flying bird duck., Parental care is highly developed in birds. Nest, building is seen., Aves is classified into two subclasses , archaeornithes and neornithes. (See flow chart), Perching mechanism is the characteristic, phenomenon of birds due to which the birds are, able to sleep on a twig without falling down., When the birds settle on the branch of a tree, the, legs are bent and puts the flexor tendons on the, stretch. With the exertion of the pull, the toes are, bent spontaneously around the perch., Marine birds have salt glands., During migration, birds determine compass, direction using celestial bodies, sun during day, and stars at night., The migration in birds is initated by photoperiod, i.e., the day light affecting the endocrine glands., Poor will / Night Jar/Goat sucker, a short billed, wide mouthed nocturnal insectivorous birds, undergo hibernation., Arrangement and distribution of feather is called, pterylosis., Quills (flight feathers) are large feathers. Feathers, of wings are remiges and tail are retrices., Other types of feathers are coverts (cover the base, of wing quills), contours (quill feather on general, covering of body having poorly developed, barbules), filoplumes (distributed among contour, feather), down feathers (cover body of newly, hatched bird or also occur beneath contours) and, bristles, powdery down feathers etc., Filoplume and down feather help in the insulation, of the body., Distinct types of flight seen in birds are flapping, , l, , l, l, l, l, l, l, l, l, l, , l, l, l, , l, l, , flight (main type), gliding (skimming), soaring, (sarling) and hovering (peculiar variant of, flapping)., Humming birds (Cuba), Mellisuga helenae, is, the smallest bird (length 5.5 cm) which can fly, forward and backward in both direction., Ostrich is the largest living bird., Dodo is a flightless bird (eg., Raphus solitarius), of Mauritius which became extinct in 17th century., Tallest Indian bird is crane/saras (Crus antigone)., Bird with longest tail (11m) is Onagadoris., Highest bird flier is Cygnus cygnus/Whooper Swan, (27000 ft)., Deepest diver bird is Emperor Penguin/, Aptenodytes foresteri., Fastest swimming bird is Gentoo Penguin/, Pygoscelis papua., Largest bird nest is of Bald Eagle/Heliacetus, leucocephalus., Poisonous bird is Pitohui dichrous (hooded, pitohui) of Papau New Guinea. It possesses toxins, in its skin and feathers., Hornbill is emblem of BNHS (Bombay Natural, History Society)., Most abundant bird is house sparrow/Passer, domesticus., Slowest flying bird is American Woocock/Scolopax, minor (8 km/hr). Largest flying bird is Albatross, (Diomedea) which is a marine bird., Fastest bird is the swift., Different types of feet are present in birds. These, are perching (sparrow), raptorial (owl),, scratching (fowl), swimming (duck), running or, cursorial (ostrich), climbing and clinging (wood, pecker), wading (jacana and heron)., Table : Types of beaks in birds, Type, Example, 1., 2., 3., 4., 5., 6., 7., 8., 9., , Seed eating, Cutting, Fruit, Insect eating, Fish eating, Flower probing, Spatulate, Water and mud straining, Tearing and piercing, , Sparrow, Crow, Parrot, Hoopoe, Kingfisher, Humming bird, Spoonbill, Duck, Eagle and owl
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 125, , ►ĺŐŕęďŚĚř, , Table : Important examples of birds, Important notes, , Scientific name, , Flying birds, 1., , Passer domesticus, [House sparrow], , Small bird, sexual dimorphism is distinct, breeding occurs almost throughout the, year. Omnivorous but chiefly granivorous., , 2., , Corvus splendens, [Crow], , Omnivorous, adapt in stealing, intelligent, cunning and audacious. House crow acts, as efficient municipal scavanger., , 3., , Psittacula krameri, [Parrot], , Commonly called rose ringed parakeet. Can imitate human speech., Spread fatal chlamydial respiratory disease called psittacosis., , 4., , Columba livia, [Pigeon], , Gregarious, omnivorous, monogamous., , 5., , Pavo cristatus, [Peacock], , National bird of India. Polygamous, feed on reptiles, birds, insects etc., , 6., , Eudynamys scolopaceous Nest parasite and lays its eggs in a crow’s nest, [Koel of Indian nightingale] Sexual dimorphism is well marked., , 7., , Piocetus species, [Weaver bird], , Constructs retort shaped nests, , 8., , Struthio camelus, [African ostrich], , l, , Flightless birds, , l, l, l, l, , 9., , Rhea, [South American ostrich], , l, l, l, l, , 10. Casuarius, [Cassowary], , l, l, l, , 11. Dromaeus, [Emu], 12. Apteryx, [Kiwi], , l, l, l, , l, , 13. Aptenodytes foresteri, [Penguin], , l, l, l, , Shows discontinuous distribution. Have well developed powerful legs, small, head, rudimentary eyes & wings., Polygamous, largest living birds (height 2.5 m and weight 150 kg)., Fast runner 60 km/hr, Eggs are the largest, Easily domesticated, Smaller than true ostrich (1.5m), Rudimentary wings are better developed, Fond of bathing and able to swim, Used in the manufacture of feather clusters, Occurs in Australia and New guinea, 3rd largest flightless bird, Nocturnal and frugivorous, Australia, 2nd largest living bird, Smallest living (50 70cm) flightless terrestrial bird, possesses a keen sense of, smell. Nocturnal and burrowing in habit., National bird of NewZealand, Occur in flocks in Antarctica region and some islands of South Africa, Good swimmers and divers, Eggs are incubated by males with the help of loose fold of skin present in be, tween the two legs.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 126, , ŕďőĽę– ĐĽŐńŐĹť, , Name, , Table : Bird sanctuaries, Bird found, , Sultanpur (Lake) Bird Green pigeon, Saras, Sanctuary, Gurgaon, crane, Spoonbill, Duck, Haryana, Govind Sagar Bird Teal, Duck, Goose,, Sanctuary, Bilaspur, Crane, Himachal Pradesh, Keoladeo Ghana Bird Siberian crane, Storks,, Sanctuary, Bharatpur, Herons, Cormorant,, Egret, Rajasthan, Chilka Lake Bird Flamingo, Pelican,, Sanctuary, Balagaon, Egret, Ibis, Sandpiper,, Cormorant, Orissa, , MAMMALIA, l, , l, l, , l, l, , l, , l, l, l, l, l, l, l, l, l, l, , Mammals are homoiothermal hairy quadrupleds, with mammary glands (modified sweat glands), in the female for suckling of young ones., Body distinctly divisible into head, neck, trunk, and tail., Skin possess sweat and sebaceous glands (peculiar, to mammal only) and sometimes scent glands in, both the sexes., Skull is dicondylic. Vertebrae are acoelous or, amphiplatyon., Cervical vertebrae are seven in number with, variation of 69 in sloth (order edentata), sea cow, and manatee (order sirenia)., Teeth are thecodont (embedded in sockets),, heterodont (four different types – incisors, canines,, premolars and molars) and diphyodont (two sets, milk teeth and permanent teeth)., Respiratory and digestive tracts are separate due, to development of secondary palate., An epiglottis is present over the opening of trachea, or larynx., Pleuric cavity is coelomic., Respiration is always by lungs., Diaphragm is present which separates the anterior, thoracic cavity from the posterior abdominal cavity., Kidney is metanephric and excretion is ureotelic., Sinus venosus is absent., Urinary bladder is present., Heart is 4 chambered with double circulation., Renal portal system is absent., Erythrocyte are biconcave and enucleate., , l, , l, , l, l, l, l, l, l, l, l, l, , l, l, l, l, l, , l, l, , l, l, l, , l, l, l, l, , Brain (with 4 optic lobe) is highly evolved with, 12 pairs of cranial nerves. Senses are well, developed., Optic lobes are converted into corpora, quadrigemina. Corpus callosum connects the two, cerebral hemispheres., External ear or pinna is present., Sexes are separate, with well marked sexual, dimorphism., True placenta is allantochorionic., In males the testes descend outside the body in, scrotal sacs., Fertilization is internal., Mammals are viviparous where the foetus is, nourished by the mother through placenta., The eggs are small and alecithal., Mammals have evolved from reptiles like, Dimetrodon in triassic., Class mammalia is divisible into three subclasses, prototheria, metatheria and eutheria. (see flow, chart)., Metatheria and eutheria are collectively called, theria., Prototheria are primitive mammals which lay, eggs., Platypus/Echidna is called the living fossil of, chordata or mammals., Duck Billed Platypus is the connecting link, between classes reptilia and mammalia., In Spiny Ant Eater, second claw of each hind limb, is longer and curved which is used for cleaning, spines and fur. Hence called toilet claw., Milk glands are functional in both sexes. In male, the phenomenon is called gynaecomastism., In metatheria (marsupials), marsupial pouch is, present where the youngs are developed. They are, often called as pouched mammal, e.g. Kangaroo., Marsupials are viviparous., Corpus callosum is absent in marsupials., In eutheria, placenta is large and intrauterine, development is prolonged. They are known as, placental mammals., Eutherians are also viviparous., Corpus callosum is present in eutherians., The period between fertilization and delivery is, called gestation period., Gestation period is shortest in opossums (1213, days) and the longest in elephant (609 days).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ĺŐŕęďŚĚř–, l, l, l, , l, l, , l, , l, , l, l, l, l, l, , l, l, , l, , l, l, l, l, l, l, , Kangaroo is the national animal of Australia., Flying Lemur has a hairy fold of skin, called, patagium which helps in gliding., Bats belonging to the order chiroptera avoid, collision (during flying) by the help of eco, apparatus or radar mechanism present in them., Tree shrew is believed to be the remote ancestor, of apes/humans., Female of Armadillo (Dasypus novemeinctus), produces four to eight young ones of one sex due, to breaking of embryo. These are the only living, mammals that have bony plates in their skin., Indian Pangolin or scaly ant eater has small stones, in its stomach (like gizzard of birds). It is therefore,, also called ‘bajrakit’., Rabbit is crepuscular (move out in twilight),, cursorial (runner with leaps), fossorial (in, burrows), coprophagus (eating its own faecal, matter) and polygamous., Young ones of rabbit are born naked, deaf and, blind., Mouse is smaller than rat., Blue whale has a thick insulating layer of fat or, blubber occur below the skin., Upper jaw of whale bears a whale bone consisting, of two rows of 600 800 plates., In the order carnivora (seal, bear, panda) large, canines and carnassial teeth (first molars of lower, jaw and last premolars of upper jaw) are present, for torning flesh., Dolphin is a highly intelligent aquatic mammal, which can imitate human laughter., Hippopotamus is the second bulkiest land, animal, living most of the time in water, hence, called riverine horse., The cells of camel can tolerate dehydration upto, 40%. This helps the camel to function as ship of, desert and remain without water for 10 15 days., Giraffe is the tallest mammal (5.48 to 6.1 mts)., Fastest mammal is cheetah (speed upto, 100 km/hr)., Slowest terrestrial mammal is 3toed sloth/, Bradypus tridactylous (speed 100150 mt/hr)., Slowest aquatic mammal is Enhydra lutris (speed, upto 10 km/hr)., Rhino is hunted for its horn, the matted hair., Antlers (found in deer) are solid bony horns which, shed and regrown every year., , l, l, , l, l, l, , l, , l, l, , l, l, , l, , l, , l, l, l, , l, l, , 127, , Tiger or Panthera tigris is National animal of, India., Primates, evolved from tree shrew, are intelligent, mammals with convoluted cerebral hemispheres,, grasping hands, binocular vision etc., Two types of primates are prosomians (before, monkey) and simians (monkeys)., Prosomians included lemur, loris and tarsiers and, simians include monkey, apes and humans., Cebus capucinus, Ateles or spider monkey are the, examples of New World Monkey and they are, found in Asia and Africa., Old World Monkeys are found in Central and, South America. Examples – Rhesus monkey, langur, or leaf monkey., Human with a language is the most advanced of, all animals., Locomotion in mammal is– climbing scansorial,, flying volant, running cursorial, jumping , saltatorial., Stripes of no two zebra are alike., Smallest mammal is Hog Nose Bat (previously, Pigmy water shrew was considered as, smallest)., Blue whale is the largest living animal with a, length of upto 30 50 mts and a weight of 135 209, metric tonnes., 2 1, 2, 3, Dental formula of man is i , c , pm , m ., 2 1, 2, 3, 2, 0, 3, 3, Dental formula of rabbit is i , c , pm , m ., 1, 0, 2, 3, Sea lion is a large eared seal., Elephants belonging to the order proboscidea are, the largest land animals reaching a height of 3.0, to 3.45 mts and weight of 5 7 tonnes., Apes are manlike primates without tails. The only, ape found in India is Gibbon., Feet of mammals are , –, Plantigrade : Walking or running with whole, sole of the foot touching the ground, e.g., bear,, human being are plantigrade while walking, but become digitigrade while running., –, Digitigrade : Walking or running with only, the digits touching the ground, e.g., rabbit,, elephant., –, Unguligrade : Running or walking on the, tips of the digits. Heels raised above the ground, level, e.g., cow, deer, horse etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 130, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 16, , Tools and Techniques in, Cytology, l, , l, l, l, , l, , For the advancement of researches in science and, to increase our knowledge about minute things,, various tools and techniques have been used by the, workers., Tools for cell study are devices and instruments, called microscopes., Techniques are skills required to aid study of cells, and their components., They are histological preparations, cytochemistry,, autoradiography, cell fractionation, biochemical, techniques and tissue culture., Modern techniques and analytical instruments are, used to understand the various structural and, functional organization of living beings., , MICROSCOPE, l, l, l, l, l, l, , l, l, , l, , First of all Leeuwenhoek (1683) used hand lenses, to study a thin slice of bottle cork., Leeuwenhoek is often called the father of, microscopy., Robert Hooke in the 18th century used a compound, microscope., Later on various improvements have been done in, microscopy., The microscope is the first powerful tool used in, the biological studies for magnifying minute objects., The most common microscope, a basic tool of, cell biologists, is the bright field light microscope, or compound microscope., A microscope has both magnification and, resolution power., Magnifying power is the ratio of magnified image, of a microscope to that formed in the retina of an, unaided eye., Magnifying power is represented by the following, equation:, , l, , l, , l, , l, , l, , Magnification =, Size of retinal image with the instrument, Size of retinal image with unaided normal eye, Since most cells are between 1 and 10 mm in, diameter, they can be observed by light, microscopy and it allows the observation of some, of the larger subcellular organelles, such as nuclei,, chloroplasts and mitochondria., The resolution or resolving power is the ability, of an optical system to separate details of two, closely placed objects., The resolution power of the unaided human eye, is 0.1 mm (100 mm or l micron = 1 mm ) and, 1000, that of the light microscope is 200 nm., The resolving power of microscope depends upon, the wavelength of illuminating agent (l) and, light gathering capacity of objective lens, called, numerical aperture (NA). It represents width of, cone of illumination. The greater the numerical, aperture the greater the resolution power., The limit of resolution (l) of any optical instrument, (i.e. eye or microscope) is given approximately, by the Abbe’s relationship., wavelength ( l ), , l, , Resolution (l) = numerical aperture (n sin a ), where,, –, l (lambda) is the wavelength (“colour”) of the, illumination or radiation used to form the image,, –, n is refractive index (a function of density) of, the material (i.e., mostly air or water) between, the specimen and the first lens (or objective, lens), and, –, sin a is sine of the semiangle of aperture of, the first lens as viewed from the specimen., The quantity “n sin a” is often called the numerical, aperture (NA).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♀ŐŐńř– ďňę– ♀ĚĘĺňĽŔśĚř– Ľň– ►ťŚŐńŐĹť, , Compound or Light microscope, l, l, , l, , l, , Compound or light microscope was invented by, Z. Janseen., It is the simplest, widely used microscope having, three parts – condenser, objective lens and occular, (eye) lens., In this microscope an object can be magnified, upto 1000 times and the magnification is, independent of intensity of light, size of microscope, and numerical aperture., In this microscope sharp images are produced only, if the material is properly fixed and stained., , l, l, , l, , l, l, , l, l, l, , l, , l, , It was invented by Zermicke in 1935 and was, awarded Nobel Prize in 1953 for this work., The microscope has a phase plate and an annular, diaphragm., They bring about changes in the light rays passing, through the specimen producing differences in light, intensity., Denser parts alters path of light more than the, thinner parts., This produces varying contrast for different regions., Phase contrast microscopy enhances the contrast, between cells and their environments and between, internal organelles and their surroundings., Phase contrast microscope is commonly used –, –, For observing living or unstained cells., –, In the observation of cells cultured in vitro, –, To study the effect of different chemical and, physical agents on the living cells and to, examine the artifacts introduced by different, methods of fixation and staining., Phase contrast microscope enables one to see, mitochondria, mitotic chromosomes, nucleoli, and other organelles quite clearly in living cells., , l, l, l, l, , l, , l, l, l, l, , l, , l, , l, , It is also used for study of living structures., Here light is split into beams by prisms, one passing, through the object and the other along the object., The first beam of light undergoes phase change, or diffraction. The second does not undergo any, change. The two beams come together over the, object. This gives bright contrast., Colour contrast is also produced by light passing, through prisms., , It is a modification of ultraviolet microscope which, was made by Coons (1945)., This instrument used long wave ultraviolet rays, for illumination., It has complementary filters which allow the viewers, to observe directly with the eyes., The microscope is useful in detecting those, components which show autofluorescence (e.g.,, chlorophylls, collagen fibrils, vitamin A)., Others can be made fluorescent by coating with, fluorochrome dyes (like acridine orange and, coriphosphine) and minerals, e.g., proteins, lipids,, starch, glycogen, etc., The light emitted by them is red, orange, yellow, or green against dark field., It is called secondary fluorescence., The technique is used in diagnosis of viruses,, bacteria and protozoa., Immunofluorescent antibody labelling technique, is used in diagnosis of specific molecules like, antigens and antibodies., It involves conjugating specific fluorochromes with, specific antibodies., , Darkfield microscope, l, l, , Differential interference contrast microscope, l, , Interference microscope gives better images of, living structures., The interference microscope, like phase contrast, microscope, depends for its functioning on changes in, the speed of light as it passes through different materials., It also allows deciphering of thickness and, determination of several light absorbing chemicals, like nucleic acids, proteins, lipids, etc., , Fluorescent microscope, , Phase contrast microscope, l, , 131, , Ultramicroscopy (or dark field microscopy) is, discovered by Zsigmondy, 1905., Ultramicroscopy is a simple modification of, ordinary microscope, where the condenser, illuminates the object obliquely so that the object, appears bright and background dark. It helps in, detecting objects smaller than those seen with, the light microscope., , Electron microscope, l, l, , M.Knoll and E.Ruska, two german scientists,, invented the electron microscope in 1932., It is a large sized instrument which has an internal, vacuum, high voltage (50, 000 1, 00, 000 volts),
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 132, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , a cooling system, a fast beam of electrons (0.54Å, wavelength), a cathode filament of tungsten,, electromagnetic lenses (each having a coil of wire, enclosed in soft iron casing) for focussing, magnification and projection and a fluorescent, screen or photographic plate for observation., Wavelength of electron beam is 10,000 times shorter, than wavelength of visible light. As a result, resolving power of electron microscope is very, high., A high vacuum is required because electrons are, very small particles as compared to even the smallest, atoms (1.06Å for hydrogenation)., For the same reason the specimen to be studied, must be ultra thin, completely dehydrated and, treated with chemicals and dyes to enhance contrast., Images obtained in electron microscope have, usually black grey and white shades. Computer is, used to enhance contrast and develop colour., Electron microscope has a very high resolution, power and magnification. It has helped discover, a number of small cell organelles (e.g., E.R.,, ribosomes,, centrioles,, microtubules,, microfilaments, intermediate filaments,, plasmodesmata, microbodies)., Detailed structure of larger cell organelles could, be known only with the help of electron, microscope, e.g., chloroplast (thylakoids, grana,, DNA, ribosomes), mitochondrion (membranes,, elementary particles, DNA, ribosomes), Golgi, apparatus (vesicles, cisternae)., Electron microscope is of two types – transmission, and scanning electron microscopes., , Transmission electron microscope, l, An ultra thin section is first dehydrated and then, impregnated with electron opaque chemicals like, lead acetate, phosphotungstate, uranium, palladium, or gold., l, The coating is essential for providing contrast and, helping the material to withstand electron, bombardment., l, The section is now placed over a copper grid in, specimen chamber. A beam of electrons is passed, through it by means of electromagnetic condenser., l, The electron beam coming out of the section is, then spread and projected over a fluorescent screen, or photographic plate by electromagnetic lenses., , l, l, l, , l, , l, l, , Magnification is 13 lakh., Resolving power is 2 10Å., TEM is the most commonly used electron, microscope which provide two dimensional, image. This is built by Ruska and his colleagues., Study of viruses, mycoplasma and other small, entities could also be made possible with the advent, of electron microscope., Advantage – High resolution (0.5 nm in practice)., Disadvantages are –, –, The specimen must be dead because it is, viewed in a vaccum., –, It is difficult to be sure that the specimen, resembles a living cell in all its details because, preservation and staining may change or, damage the structure., –, Expensive to buy and run., –, Preparation of material is time consuming and, requires expert training., –, The specimens gradually deteriorates in the, electron beam. Photographs must therefore be, taken if further study is required., , Scanning electron microscope, l, It is used for obtaining 3dimensional and surface, images. The microscope was invented by Knoll, (1935)., l, The specimen to be studied is first super cooled, (in liquid propane at –180°C) and then dehydrated, in alcohol (at –70°C)., l, It is then coated with gold, platinum or some other, metal for creating a reflecting surface for electrons., l, The surface is scanned by a narrow beam of, electrons (upto 200Å in diameter)., l, The secondary electrons emitted by the surface, of specimen are collected by a positively charged, grid and then passed over to a fluorescent screen, or photographic plate through a television tube., l, Magnification of SEM varies from 15 2,00,000., Resolution power is 5 20 nm., l, Advantages are –, –, Surfaces of structure are shown., –, Great depth of field, meaning that a large part, of the specimen is in focus at the same time., This gives a very striking three dimensional, effect., l, Disadvantage – Resolution (520nm) is not as, great as with a TEM (0.5 nm).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 133, , ♀ŐŐńř– ďňę– ♀ĚĘĺňĽŔśĚř– Ľň– ►ťŚŐńŐĹť, , Other high powered microscopes, l, , l, , l, , Scanning probe microscope : The microscope is, capable of resolving the outer texture of the material, to the minutest detail since it has the potential to, image even a single atom. Magnification is upto, 100 million., Scanning tunnelling microscope : It has a tiny, tungsten probe for moving over the surface of, specimen. The microscope is used to detect defect, in electrical conductors and computer chips., Atomic force microscope : It has an extremely, fine diamond probe for moving over the surface, of biochemicals. Oscillations produced in the probe, are changed into images by a computer. The, microscope is useful in viewing detailed structure, of biological molecules, e.g., DNA, proteins., , l, l, , l, , l, , l, , XRAY CRYSTALLOGRAPHY, l, , l, , l, l, , l, , l, l, , Xray crystallography (Xray diffraction; Bragg,, 1913) is an important technique in molecular, biology to analyze the structure and orientation of, molecules, distance between molecules and their, atomic organization. It is based on the diffraction, of radiations when they counter small obstacles., The molecular structure of DNA was based on, Xray diffraction study by Wilkins, Astbury and, Franklin (1953) for which Wilkins shared Nobel, Prize of 1962 with Watson and Crick., Myoglobin was the first protein whose structure, was determined by Xray diffraction., Polarization microscopy is useful mainly for, viewing highly ordered objects such as crystals, or bundles of parallel filaments., The mitotic spindle, made up of microtubules, cannot be resolved by light microscope, but can, be studied with polarizing microscope., Ultraviolet microscope uses the UVrays of shorter, wavelengths (1500–3500 Å)., The ultraviolet microscope is useful in the, qualitative and in some cases quantitative, determination of nucleoproteins., , CELL FRACTIONATION, l, , Cell fractionation is a technique by which a tissue/, cell is disrupted by mechanical/chemical/ enzymatic, methods to release the cell components (organelles, and macromolecules) followed by their separation, , l, , by differential centrifugation according to physical, properties like mass, specific gravity, surface tension, etc., Cell fractionation is a two stage process–, homogenization and differential centrifugation., In homogenization cells are disrupted/, disintegrated/ broken mechanically by applying, pressure in potter homogenizer or by grinding or, by insonation (ultrasonic vibrations by sonifier)., Usually 0.25 M to 0.8 M sucrose solution is used, in which the released cell components do not change, their properties as well as preserve the cell, organelles and prevent their clumping., Differential centrifugation is the mechanical, separation of individual subcellular components from, the homogenate by centrifugation at different speeds., Density gradient centrifugation is used for the, separation of macromolecules like virus particles,, nucleic acids., Classical cell fractionation technique may be, summarized as follows –, Homogenate in 0.25 sucrose solution, or cesium chloride solution, 1st centrifugation 700 × g for 10 min, SupernatantI + SedimentI, 2nd centrifugation, , 5000 × g for 10 min, , SupernatantII + SedimentII, Redispensed, 3rd centrifugation 24, 000 × g for 10 min, SupernatantIIa + SedimentIIa, 4th centrifugation, , 54,000 × g for 10 min, , SupernatantIII + SedimentIII, , 5th centrifugation 1,00,000 × g for 10 hrs, SupernatantIV + SedimentIV
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 134, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The cellular extract is mixed with cesium chloride, on concentrated solution of sucrose and centrifuged, at 100000 rpm for 20 hours. The chemicals come, to settle in the density gradient according to the, density of their molecules., Meselson and Stahl (1958) proved the semi, conservative nature of DNA replication in, prokaryotes by using density gradient centrifugation., Svedberg unit is a unit of measurement of, sedimentation rate or sedimentation coefficient of, a particle in an analytical ultracentrifuge., , l, , ELECTROPHORESIS, l, , l, l, , l, , l, , l, , l, , l, , l, , Electrophoresis is a technique in which particles, of different sizes and charges are separated due to, their movement to different distances under the, influence of an electric field, e.g., nucleic acids,, proteins, amino acids, nucleotides, etc., This technique was developed by Reuss and, modified by Tiselius (1937)., A base material is used for the passage of molecules, of the mobile phase. For smaller amount of substances,, a supporting media such as polyacrylamide gel,, agarose gel or starch gel is used., In PAGE (polyacrylamide gel electrophoresis) the, base material is polyacrylamide or polymer of, acrylamide and methylene bisacrylamide., In agarose gel electrophoresis, the base material, is agarose. The base material dip in solution having, cathode at one end and anode at the other end., As the electric current is switched on, the chemicals, of the mixture separate and pass to different, distances. The gel functions as a sieve., In two dimensional electrophoresis, molecules are, separated in two directions at right angle to each, other with denaturing conditions in one direction, and nondenaturing conditions in other direction., In immunoelectrophoresis antibodies coupled with, radioisotopes, specific enzymes or fluorescent dyes, are used in detection of particular proteins., This technique is highly sensitive. It can separate, molecules in picogram and nanogram quantities, and distinguish proteins which differ from each, other in only one amino acid., , AUTORADIOGRAPHY, l, , Autoradiography is a photographic technique using, radioactive isotopes (tracer precursor intermediates), , l, , l, , l, , emitting radiations for studying the functions of, –, The cell synthesis of biomolecules,, –, Locating a particular chemical constituent,, –, Tracing the metabolic pathways or events, inside the living cells., –, Tritiated ( 3H) and carbon labelled ( 14C), compounds of thymidine, uridine and, aminoacids (leucins) are used to study, synthesis of DNA, RNA and proteins, respectively., The radiation reduces the silver salt of the, photographic emulsion to produce metallic silver, grains that form the image. The patterns of, distribution of silver grains represent the sites where, radioisotopes is present in the sample. This, technique was used by Calvin and his coworkers, for studying the path of labelled carbon in, photosynthesis and led to the establishment of, Calvin cycle., Radioactive isotopes are unstable isotopes which, emit positively or negatively charged particles. eg, 14C (C14), 3H (H3), 131I (I131), 32p (p32)., Reasons for their importance in biological, studies are –, –, It can be incorporated into any biological, molecule., –, It has very long half life., The radioactivity of these isotopes can be recorded, by beiger counter or scintillation counter or, autoradiography., , CHROMATOGRAPHY, l, , l, , Chromatography is a technique of separating, molecular components of a mixture of a mobile, phase by using the principle of partition, coefficient due to which different molecules move, at different rates through a stationary phase and, get separated., Chromatography is of several types –, –, Adsorption or column chromatography : The, stationary phase consists of a column of charcoal,, silica, alumina, calcium carbonate or magnesium, oxide. The solution is made to percolate through, this column when different chemicals get, absorbed at various levels. The technique is, useful for separation of tissue lipids., –, It is the first type of chromatography that, was developed by Mikhail T. Swett (1906).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 135, , ♀ŐŐńř– ďňę– ♀ĚĘĺňĽŔśĚř– Ľň– ►ťŚŐńŐĹť, , –, , –, , –, , –, , –, , Thin layer chromatography : The stationary, phase consists of a thin plate of cellulose, powder or alumina. As a few drops of mixture, are poured over it, the different chemicals, spread to different distances. The method is, useful in separation of amino acids,, nucleotides and other low molecular weight, products., Paper chromatography : A paste of mixture, is applied near one end of a chromatographic, paper (or Whatman 1). The lower end below, the paste is dipped in a solvent. As the solvent, rises in chromatographic paper, the different, chemicals of the mixture spread to different, distances. The paper can be rotated to obtain, two dimensional chromatogram., Ion exchange chromatography : Beads of, cellulose and other materials having negative, and positive charges are placed in a column., The mixture (of mobile phase) is poured over, the column. As the mixture passes through, the column, its constituents separate according, to their charges. The technique is used in, purification of insulin, plasma fractionation, and separation of proteins., Gel fractionation chromatogr aphy, (molecular sieve chromatography) :, Dextran gel sephadex is available with, various pore size. A mixture is poured over, a column of sephadex. The various chemicals, pass through the pores and come out of the, column with heavier larger molecules do so, first followed by progressively smaller sized, molecules provided the pores are larger than, the size of largest molecules. The technique, is used in determining the molecular, weight of proteins by calibrating the, colum n with proteins of diffe rent, molecular weights., Affinity chromatography : Stationary phase, consists of column of ligands (molecules that, bind to other specific molecules at particular, sites). Mixture is allowed to pass through the, column. Chemical linkages are establised, between ligands and their specific chemicals., Others pass out of the column. The technique, is use d in separ ation of enzym es,, immunoglobulins, mRNA etc., , SPECTROPHOTOMETRY, l, l, l, , l, , l, l, , l, l, l, , Spectrophotometry is the quantitative study of, electromagnetic spectra., Spectrophotometry involves the use of a, spectophotometer., A spectrophotometer is a photometer (a device, for measuring light intensity) that can measure, intensity as a function of the colour, or more, specifically, the wavelength of light., There are many kinds of spectrophotometers., Among the most important distinctions used to, classify them are the wavelengths they work with,, the measurement techniques they use, how they, acquire a spectrum, and the sources of intensity, variation they are designed to measure., Other important features of spectrophotometers, include the spectral bandwidth and linear range., Perhaps the most common application of, spectrophotometers is the measurement of light, absorption, but they can be designed to measure, diffuse or specular reflectance., Strictly, even the emission half of a luminescence, instrument is a kind of spectrophotometer., There are two major classes of spectrophotometers–, single beam and double beam., A double beam spectrophotometer measures the, ratio of the light intensity on two different light, paths, and a single beam spectrophotometer, measures the absolute light intensity., , SECTIONING, l, l, l, , l, , l, l, , For the microscopic studies of biological materials, it is essential to cut thin sections of these materials., It can be done either by hand sectioning with the help, of razor or by section cutting machines called microtomes., Microtome is an instrument used to cut thin sections, (5 to 10 µm i.e., 5,000 to 10,000 nm) of fixed, material for microscopic studies., Ultramicrotome has glass or diamond knife to, cut ultra thin sections of 0.01 to 0.05 µm thickness, (= 10nm to 50 nm) required in electron microscopy, and Xray microscopy., Freezing microtome uses both living and fixed, materials., Microtome was invented by W. His. In electron, microscope thin sections of 20 – 100 nm are, required. For this ultramicrotome and glass knife, of diamond are used.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 136, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Dyes used to stain various cell components, Stain, , Used for staining, , Final colour, , 1., 2., , Acetocarmine, Acid fuschsine, , Pink, Magenta, , 3., 4., 5., 6., 7., 8., 9., , Aniline blue (Cotton blue), Basic fuschsine, Crystal violet, Eosin, Feulgen’s stain, Hematoxyline, Iodine solution, , Chromosomes, Cortex, cellulose walls, pith parenchym,, mitochondria, Fungal hyphae and cellulose cell walls, Nucleus, mucin and bacteria, Nuclei and chromosomes, Cytoplasm, DNA, Nuclei, cell wall and cellulose, Starch, Cellulose proteins, insulin deposits, Pectin, cutin, callose, , 10., 11., 12., 13., 14., 15., 16., 17., 18., , Janus green B, Methylene blue, Phloroglucinol + HCl, Ruthenium red, Safranin, SudanIII or IV, Sudan black, Toludine blue, PAS (Periodic acid schiff), , 19. Malachite green, , Fungi and mitochondria, Yeast and Golgi complex, Lignin, Pectin, Nuclei, lignified tissues, Suberin, cutin, oil, Fatty sustance, RNA, Plants cells for starch cellulose, hemicelluloses, and pectins and on animal cells for mucin,, mucoproteins etc, Cell walls, endodermis, cytoplasm, chloroplast,, nuclei, , CYTOCHEMISTRY, l, , l, , l, l, , Cytochemistry is a technique used for the, localization and identification of different chemicals, in the cells., Most of the cell components are transparent, so to, make these components visible, different dyes are, used to stain them., The cellular components take up these dyes, according to their chemical nature., Out of these stains, some stains can be used for, staining living materials as they are nontoxic,, such stains are called vital stains. e.g., methylene, blue, neutral red, janus green, malachite green,, etc., , Blue, Magenta red, Violet, Pink, Purple or red, Violet, Blue, Brown, Yellow (in, section of fresh, material), Green, Blue, Bright red, Red, Red, Scallet red, Black, Blue, Red / Purple Blue, , Emerald green, , TISSUE CULTURE, l, , l, , l, l, , Tissue culture (in vitro culture) is a technique of, culturing mature living somatic nucleated cells in, natural or synthetic medium under aseptic conditions., Tissue culture was developed by Harrison(1970) who, successfully cultured small pieces of frog’s embryonic, spinal cord, but the concept of tissue culture was, conceived by Haberlandt (1902), when he thought, of growing isolated mesophyll cells of a leaf in aseptic, culture for propagation of the whole plant., White (1932) was the first to raise a tissue culture., White (USA) and Gantheret and Nobecourt of, France in 1939 raised callus (an undifferentiated, unorganized actively dividing mass of cells.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńń– ďř– ď– ♂ňĽŚ– Őě– ▌ĽěĚ–, , 137, , Chapter 17, , Cell as a Unit of Life, l, , l, , l, , l, l, , l, , l, l, , l, , Cell is the fundamental structural unit of all, living organisms and is sometimes called the, ‘building block of life’., The cell consists primarily of an outer plasma, membrane, which separates it from the, environment; the genetic material (DNA) which, encodes heritable information for the maintenance, of life; and the cytoplasm, a heterogeneous, assemblage of ions, molecules, and fluid., Cells are the smallest structures capable of basic, life processes, such as taking in nutrients, expelling, waste, and reproduce new cells that perpetuate, life., All living things are composed of cells., Some microscopic organisms, such as bacteria and, protozoa, are unicellular, meaning they consist, of a single cell. Plants, animals, and fungi are, multicellular; that is, they are composed of a, great many cells working in concert., Cells require energy for a variety of functions,, including moving, building up and breaking down, molecules, and transporting substances across the, plasma membrane. Nutrients contains energy, but, cells must convert the energy locked in nutrients, to another form specifically, the ATP molecule,, the cell’s energy battery before it is useful., Word cell is derived from the Latin word ‘cellula’, which means small component., The first observations of cells were made in 1665, by English scientist Robert Hooke in a thin piece, of bottle cork. He actually observed only cell walls., Noting the rows of tiny boxes that made up the, dead wood’s tissue, Hooke coined the term cell, because the boxes reminded him of the small cells, occupied by monks in a monastery. While Hooke, was the first to observe and describe cells, he did, not comprehend their significance., , l, l, , l, , l, , l, l, l, , l, , l, , l, , l, l, , Robert Hooke wrote his findings in a book titled, “Micrographia”., At about the same time, the Dutch maker of, microscopes Anton van Leeuwenhoek pioneered, the invention of one of the best microscopes of, the time., Cells may have come from stable bubbles called, protobionts which can maintain internal chemical, environments that differ from their surroundings., In the 1920s, the Russian scientist Alexander, Oparin formed unique bubbles by mixing a large, protein and a polysaccharide in solution and, agitating the mixture whose interiors had, concentrations of the macromolecules that were, higher than those of their surroundings., These experiments suggest a bubble theory for, the origin of cells., The term cytology was coined by Hertwig (1893)., Cell biology or cytology is the study of all aspects, of cells and their components including their, structure, biochemistry, development and, physiology. The study of cell biology is the basis, for studying all life, whether singlecelled or, multicellular., The invention of the microscope and its, improvement leading to the electron microscope, revealed all the structural details of the cells., The most common microscope, a basic tool of, cell biologists, is the bright field light microscope, or compound microscope., The simple microscope was invented by Galileo, (1618) and first microscope was made by Robert, Hooke., The microscope has both magnification &, resolution power., Magnification is the power of enlargement, which, can be calculated by multiplying the power of eye, piece lens by the power of objective lens.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 138, , l, , l, , l, , l, , l, , l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Resolution power is the ability to distinguish, neighbouring point/object as distinct and separate, entities., Resolving power of microscope depends upon, the wavelength of illuminating agent and light, gathering capacity of objective lens, called, numerical aperture., Resolution power of unaided human eye,, compound microscope, light microscope and, electron microscope is 0.1 mm (100 µm or 1 micron, 1, mm ), 0.25 0.30 mm, 200 nm and 10Å, =, 1000, respectively., Cell were also observed prior to Hooke, by –, 1. Jan Swammerdam (1658) saw red blood cell, of frog., 2. Malpighi (1661) Examined thin slices of, plants and animals tissues and called them, ‘utricle’ and ‘saccule’., Leeuwenhoek (1672) was first to see free cells as, bacteria (in tartar of teeth), protozoa, red blood, cells and sperm swimming in semen etc., Dutrochet (1824) concluded that plants and animals, were made up of globular cells of extreme, smallness and these cells are held together by, cohesion., Working together, German botanist Matthias, Jakob Schleiden and German zoologist Theodor, Schwann recognized the fundamental similarities, between plant and animal cell., In 1939, Schleiden and Schwann formulated the, cell theory., Schleiden worked on plant cell and Schwann, worked on animal cells., Cell theory states that –, –, Living beings are made up of cells and their, products. Depending upon the number of cells,, a living being is unicellular, colonial or, multicellular., –, A cell is a mass of protoplasm having a, nucleus (some organisms are multinucleated., Multinucleated condition in plants in called, coenocyte, eg., Volvox and in animals is called, syncytium, eg. epidermis of Ascaris., –, Cells have similar structure and, metabolism., –, The functions of an organism are due to, activities and interaction of its cells., , l, , l, , l, l, , l, l, , l, , l, l, l, , l, , l, , Objections to cell theory are , –, Viruses don’t have cellular structure., –, Monerans and protistans are acellular., –, Certain organisms are multinucleate., –, A typical nucleus is absent in prokaryotic, cell., –, Connective tissue have a lot of nonliving, material as compared to living matter., –, Certain cells lose their nuclei in the mature, state. (RBC and sieve tube cells), Cell theory was further modified by Virchow (1855,, 1858) that cells develop from preexisting cells , Omnis cellula e cellula. It is known as law of, cell lineage., Modern cell theory is known as cell principle or, cell doctrine., Cell doctrine states that –, –, Cells are the morphological and physiological, units of all living organisms., –, The properties of a given organism depend on, those of its individual cells., –, Cells originate only from other cells and, continuity is maintained through the genetic, material., –, The smallest unit of life is the cell., Protoplasmic theory was proposed by Max, Schultze (1861)., Protoplasmic theory states that living matter of, an organism is protoplasm and the cell is simply an, accumulation of protoplasm limited by an outer, membrane and containing a nucleus., Corti (1772) was the first who observed, protoplasm in cell which is named as sarcode by, Dujardin (1836)., Hugo Von Mohl (1844) gave the significance of, protoplasm., The term protoplasm was coined by Purkinje, (1939)., Protoplasm is known as physical basis of life, (Huxley) and divided into nucleoplasm (protoplasm, of the nucleus) and cytoplasm (extranuclear, protoplasm)., Theories about the physical structure of, protoplasm are granular theory, fibrillar theory,, reticular theory, alveolar theory, crystallocolloidal, theory., Granular theory was propounded by Altman. It, states that granules are embedded in a fluid.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńń– ďř– ď– ♂ňĽŚ– Őě– ▌ĽěĚ–, l, , l, , l, , l, , l, , l, , l, , l, , Reticular theory was proposed by Fromann, (1885). It states that reticulum of fibres are, embedded in a fluid., Fibrillar theory was proposed by Velton, (1873 75), Flemming (1882). It states that fibrils, are dispersed in a liquid., Alveolar theory was proposed by Butchili (1878)., It states that droplets or alveoli are embedded in, liquid., Crystallocolloidal theory was proposed by Fischer, (1894). It states that substances dissolved and, dispersed in water forming both true solution as, well as colloidal solution. It is the most accepted, theory., Physical properties of protoplasm are –, –, Protoplasm is a complex, granular, elastic,, viscous and colourless substance., –, Protoplasm is selectively or differentially, permeable., –, Cyclosis or streaming movements are shown, by protoplasm., –, Protoplasm is considered to be a ‘polyphasic, colloidal system’., –, Fischer (1894) and Hardy (1899) showed its, colloidal nature., –, The chief component of protoplasm is water., Water, the main inorganic substances, varies, from 5% to 90% in different tissues, with an, average of 65% to 75%., –, Various soluble substances such as glucose,, minerals etc, remain dissolved in water and, form a true solution or crystalloid., –, In this solution various larger insoluble organic, compounds such as fatty acids, proteins and, some carbohydrates are suspended in the form, of colloidal particles such as protein and lipids, etc., constitute dispersed phase., –, Some emulsions or suspensoids are also, present and hence protoplasm is a complex, colloidal system of many places., The exact chemical composition of protoplasm, cannot be determined as it undergoes continuous, changes and its composition is not, therefore,, constant., Maximum water content in protoplasm is found in, hydrophytes, ie., 95%, whereas minimum in seeds,, spores (dormant organs), ie., 1015%., In animals, water is less (about 65%) and proteins, are more (about 15%)., , l, l, , l, , l, l, l, , l, , l, , l, , l, , l, , 139, , In plants, pH of protoplasm varies not only in, different cells but from time to time in the same cell., Although plant protoplasm is less known and, generally pH is on acidic side, but different vital, activities occur at neutral pH which is considered, as 7., In animals, nucleus is slightly alkaline (7.5 – 7.6, pH) whereas cytoplasm is slightly acidic (6.7 – 6.9, pH)., Injury decreases the pH of the cell (i.e., 5.2 – 5.5), and if it remains for a long time, the cell dies., Sachs (1874) proposed organismal theory., Organismal theory states that whole organism, functions as a single entity which is made of a, continuous mass of protoplasm incompletely, divided into cells., Cell are autonomous or selfcontained unit, because , –, they obtain or manufacture food., –, they require energy for overcoming, entropy, performing body activities and, biosynthesis, for this they oxidise food, materials in respiration, –, cells convert nonliving material into, components of living protoplasm, –, worn out parts are replaced by new ones., –, there is exchange of gases, –, cells discard waste materials, –, they are able to regulate their activities, through flow of energy and information, –, cells maintain their own internal physio, chemical environment, –, they may divide and form daughter cells, with same heredity as that of parent cell, –, there is a definite life span., Cells of unicellular organisms lead independent, existence with no dependence on others for any, function, material or information., Cells of multicellular organisms possess, autonomy but shows various interactions and, specialities for performing different functions., Multicellular organisms have 3 types of cells, regarding their capacity to divide and differentiate, undifferentiated, differentiated &, dedifferentiated., Undifferentiated cells are the meristematic cells, which possess the power of division, e.g. apical, meristem.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 140, , l, , l, , l, , l, l, , l, l, , l, , l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Differentiated cells are postmitotic specialised, cells with a distinct structure and function,, e.g. RBC., Dedifferentiated cells are specialised cells that, revert to function of division for wound healing,, regeneration, secondary growth etc., Multicellularity is more advantageous than, unicellularity because, –, it increases survival and it induces, specialization,, –, it ensures uninterrupted activity,, –, it provides division of labour,, –, outer cells become specialised to protect the, internal cells,, –, internal cells develop their own environment,, –, keeps the cells small except where they take, part in conduction and support,, –, death of a few cells or reproduction does not, kill the organism. Rather some dead cells are, functionally important, e.g. tracheids of xylem., –, differentiated cells may take over the function, of division through the process of, dedifferentiation, e.g. plant cells., Cellular totipotency is the ability of a living cell, to develop into a complete organism., Cellular totipotency was first suggested by, Haberlandt (1902), and also regarded as the, Father of tissue culture., Steward (1957) first provided the evidence of, cellular totipotency., Steward and his coworkers demonstrated that in, carrots the callus (unorganised group of cells) raised, from immature embryos is able to differentiated, embryoids identical to the zygotic embryo of this, plant., Anita Guha and S.C. Maheshwari (1966) reported, that in the anther cultures of Datura numerous, embryoids developed that had come from haploid, pollen grains., Somatic nucleated cells are totipotent or able to, produce a complete organism., Flow of information in cell is required for, performing specific functions at particular times., Information is of two types intrinsic (internal), (or genetic) and extrinsic (external) through nerves, and hormones., DNA is the master molecule which contains genetic, information for synthesis of proteins., , l, , l, , l, l, , l, , l, , l, l, , The process of RNA formation from DNA template, is known as transcription and synthesis coded in, mRNA is called translation., All physical and chemical changes tend to proceed, in such a direction that useful energy undergoes, irreversible degradation into random form called, entropy., The energy which can work at constant temperature, and pressure is called free energy., Energy flows through the plant and animal kingdom., Green plants utilize the solar energy and animal, feed upon plants to use that energy., Living cells capture, store and transport energy in, a chemical form which is called adenosine, triphosphate (ATP)., Every living cell of an organism keeps its chemical, composition steady, such balancing condition is, called homoeostasis., Bioluminescence is the production of light by living, organisms., Bioenergetics is the field of biochemistry, concerned with the transformation and use of energy, by living cells., , COMPARTMENTALIZATION AND TYPES, OF CELLS, l, , l, l, , l, l, , l, , l, , l, , Living organisms can be classified into one of, two major categories based on the location within, the cell where the most genetic material is stored., Cells are of two types prokaryotic and, eukaryotic., The term prokaryote comes from Greek words, that mean “before nucleus” or “prenucleus,” while, eukaryote means “true nucleus.”, Eukaryotic cells may have evolved from primitive, prokaryotes about 2 billion years ago., Prokaryotic cells are among the tiniest of all cells,, ranging in size from 0.0001 to 0.003 mm (0.000004, to 0.0001 in) in diameter., A prokaryotic cell has one envelope system with, no membrane lined internal organelles except, thylakoids if present., A eukaryotic cell has internal compartments. It, has double membrane system, besides cell, membrane the cell organelles are also covered by, membranes. Eg. plant cell and animal cell., Prokaryotes have no nucleus or other membrane, bounded compartments. They lack distinct
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 141, , ►Ěńń– ďř– ď– ♂ňĽŚ– Őě– ▌ĽěĚ, Table : Comparison of features of prokaryotic and eukaryotic cells, Characters, , Prokaryotes, , Eukaryotes, , Typical organisms, , bacteria, archaea, , protists, fungi, plants, animals, , Typical size, , ~ 110 µm, , ~ 10100 µm (sperm cells, apart from the tail, are smaller), , Type of nucleus, , nucleoid region; no real, real nucleus with double membrane, nucleus, , DNA, , circular (usually), , linear molecules (chromosomes) with histone proteins, , RNA/protein, synthesis, , coupled in cytoplasm, , RNAsynthesis, inside, protein synthesis in cytoplasm, , Ribosomes, , 50S+30S, , 60S+40S, , Cytoplasmatic, structure, , very few structures, , highly structured by endomembranes and a cytoskeleton, , Cell movement, , flagella made of flagellin, , flagella and cilia made of tubulin, , Mitochondria, , none, , one to several dozen (though some lack mitochondria), , Chloroplasts, , none, , in algae and plants, , Organization, , usually single cells, , single cells, colonies, higher multicellular organisms with, specialized cells, , Cell division, , binary fission, division), , l, , l, , l, , l, , (simple, , the, , nucleus, , mitosis (fission or budding), meiosis, , organelles, although some do have invaginated, membrane structures., In a prokaryotic cell, found only in bacteria and, archaebacteria, all the components, including the, DNA, mingle freely in the cell’s interior, a single, compartment., Prokaryotes inhabit the widest range of, environmental extremes. They can be found at, thermal vents deep in the ocean, living at, temperatures above boiling. They also occur in, extremely salty environments., The cytoplasm (the plasma membraneenclosed, region) of prokaryotes consists of the nucleoid, (where the DNA is concentrated), ribosomes (the, molecular protein synthesis machines), and a liquid, portion called the cytosol., Most prokaryotic cells have a cell wall just outside, the plasma membrane. [The cell wall functions to, prevent plasma membrane lysis (bursting) when, cells are exposed to solutions with lower solute, , l, , l, , l, , l, l, l, , concentrations than the cell interior. It also protects, the membrane.], In most bacteria (but not in archaea) the cell wall, is made of a polymer of amino sugars called, peptidoglycan, which is covalently crosslinked, to form one giant molecule around the entire cell., Eukaryotic cells, which make up plants, animals,, fungi, and all other life forms, contain numerous, membranebounded nucleus and usually have, other membranebounded compartments or, organelles as well., The DNA in eukaryotic cells is enclosed in a special, organelle called the nucleus, which serves as the, cell’s command centre and information library., Compartmentalization is the key to eukaryotic, cell function., The subunits, or compartments, within eukaryotic, cells are called organelles., Eukaryotic cells are typically about ten times, larger than prokaryotic cells. In animal cells, the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 142, , ŕďőĽę– ĐĽŐńŐĹť, Compartmentalization of cell, , Outside by, Plasma membrane or, cell membrane, , Internally (within cell), Comprises, Membrane, bound organelles, , Without membrane, bound organelles, (Except, thylakoids, if present), , Eukaryotic cell (double envelop system), , Prokaryotic cells, (one envelop, system), , Contain, , Protoplasm, Cytoplasm, Serves for reaction medium,, storage, exchange etc., , Basically differentiated on the basis of, – organization of biomembranes, – variety of cytoplasmic organelles, – complexity of nuclear membrane, , Nucleus, (Nucleoplasm, a clear non staining, fluid material) control centre, Contain, Nucleolus, Chromosomes, , Contain, , Semi, Cytoplasmic, autonomous organelles, organelles, Organelles, Mitochondria &, chloroplast, , With, , Single membrane : ER, golgi, apparatus, vacuoles, lysosomes,, sphaerosome, peroxisomes,, glyoxysomes, protoplast thylakoid, (lamella inside chloroplast), , Cell inclusions, * Non living granules often called, deutoplasmic substances, * Used for food and material, storage, , Double membrane : Plastids,, mitochondria, nucleus, Without, Ribosomes, centrosomes, centriole nucleolus,, membrane cytoskeletal structures, cell wall, Centrosome (2 centrioles), microtubules and, Concerned, cilia and flagella, with moving, and movements, , Present only in, , Plant cells, , Cell wall, Chloroplast (chemical factores), Vacuoles [central vacuole (large) &, tonoplast membrane], Plasmodesmata, , Animal cells, , Centrioles (self replicating organ), Cell coat, , Common to both cells, Plasma membrane, Endoplasmic reticulum, ER (transport system), Golgi apparatus (protein packing plant), Mitochondria (power house), Lysosome (suicide bag), Cytoskeletal structures, Microbodies, Sphaerosomes, Flagella and cilia, Ribosomes (protein factories)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 143, , ►Ěńń– ďř– ď– ♂ňĽŚ– Őě– ▌ĽěĚ, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , plasma membrane, rather than a cell wall, forms, the cell’s outer boundary. With a design similar, to the plasma membrane of prokaryotic cells, it, separates the cell from its surroundings and, regulates the traffic across the membrane., The eukaryotic cell cytoplasm is similar to that, of the prokaryote cell except for one major, difference: eukaryotic cells house a nucleus and, numerous other membraneenclosed organelles., Eukaryotes have a protein scaffolding called the, cytoskeleton, which provides shape and structure, to cells, among other functions., Membranes surrounding these organelles keep away, inappropriate molecules that might disturb organelle, function. They also act as traffic regulators for, raw materials into and out of the organelle., Compartmentalization in each cell is a distinct, compartment due to presence of plasmalemma., All cells at their essence have at least three things, in common cell membrane, cytoplasm and DNA, (Eukaryotes such as plants and fungi will have cell, walls in addition to the always present cell, membrane)., All eukaryotic cells are surrounded by a thin, elastic,, living covering called cell membrane, or plasma, membrane or plasmalemma., Certain protists, most of the fungi and all plant cells, have a thick, rigid, nonliving additional covering, outside the cell membrane. It is known as cell wall., The cytoplasm consists of a semifluid,, homogenous, translucent, colloidal ground, substance, formerly called the cytoplasmic matrix, or hyaloplasm, now termed cystosol., In free cells, e.g. protozoans, the cystosol has an, outer narrow, relatively firm zone, the ectoplasm, and around the centre relatively fluid mass, the, endoplasm., The cytoplasmic matrix, along with the structures, it contains, is often in constant motion, called, streaming movement or cyclosis., The cytoplasm contains mainly two types of, structures organelles (or organoids) and, inclusions., Organelles are living, protoplasmic structures, having specific functions necessary for the, metabolism of the cell, e.g. mitochondria,, chloroplast, ribosome etc., , l, , l, l, , l, , l, , Inclusions are nonliving or deutoplasmic, cytoplasmic structure, e.g. reserve food material,, pigment granules, crystals etc., The eukaryote cell are of two types plant and, animals cells., Most of the organelles and other structures of cells, are common to animals and plants. For example,, both animal and plant cells have a plasma membrane,, a nucleus, mitochondria, endoplasmic reticulum, a, Golgi apparatus, ribosomes and lysosomes., Only plant cells have a cell wall containing, cellulose. Plant cells usually contain a large, permanent vacuole contained within a special, membrane, the tonoplast. Green plant cells contain, chloroplast., Only animal cells contain two centrioles (making, up the centrosome), and often also temporary, vacuoles or vesicles., , CELL SIZE, l, l, l, , l, l, , l, , l, , l, , PPLO (pleuro pneumonia like organism) is the, smallest cell., In human beings cells of kidney are smallest and, of nerve fibre are largest., Cell coat (glycocalyx or extraneous coat) is made, up of oligosaccharides which acts as recognition, centre during organ transplantation., Longest plant cell is the fibre of Ramie Boehameria, nivea (55 cm in size)., Photosynthetic cells are called energy transducers, because they possess chloroplasts for absorbing, light energy, convert the same into chemical energy, and store as food energy., Cells vary considerably in size. The smallest cell,, a type of bacterium known as a mycoplasma,, measures 0.0001 mm (0.000004 in) in diameter;, 10,000 mycoplasmas in a row are only as wide as, the diameter of a human hair. Among the largest, cells are the nerve cells that run down a giraffe’s, neck; these cells can exceed 3 m (9.7 ft) in length., Human cells also display a variety of sizes, from, small red blood cells that measure 0.00076 mm, (0.00003 in) to liver cells that may be ten times, larger. About 10,000 averagesized human cells, can fit on the head of a pin., Nucleocytoplasmic (NP) or karyoplasmic ratio, is the ratio between volume of nucleus and volume, of cytoplasm of a cell.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 144, , l, l, , l, l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , A reduced karyoplasmic ratio either induces the, cell to divide or undergo maturation and senescence., Metabolically active cells are small as small cells, have higher NP ratio for better control and higher, surfacevolume ratio for quicker exchange of, materials., Cell size is limited by the surface areatovolume, ratio., Surface areatovolume ratio is defined as the, surface area divided by the volume. For any given, shape surface to volume ratio decreases with the, increase in cell size or volume., Shape also influences surface areatovolume, ratios., –, A sphere has the least surface areatovolume, ratio of any shape., –, Imagine you have a lump of clay. Fashioning, it into a sphere minimizes the surface area., –, If you flatten the ball of clay to make a, pancake shape, the surface area increases,, while the volume remains the same. Cells, such as red blood cells flatten into a pancake, shape to increase surface area., –, Fashioning the clay into a thin string also, increases the surface area without increasing, the volume., –, Nerve cells have this shape, which allows, some of them to be a meter long or more., –, If the clay is spherical but the surface is, irregular with many fine projections coming, off the surface, surface area is greatly, increased. In epithelial cells, such projections, are called microvilli., Most cells are tiny, with diameters in the range of, 1 to 100 µm., The surface of a cell is the area that interfaces, with the cell’s environment. The larger the surface, area of a cell, the faster a cell can take in, substances and remove waste products., , l, , l, l, , l, , The volume of a cell is a measure of the space, inside a cell. The larger the volume of a cell, the, more chemical activity it can have., The small size of cells makes the use of microscopes, necessary to view them., If two objects are too close together, they start to, look like one object. With normal human vision, the smallest objects that can be resolved (i.e.,, distinguished from one another) are about 200, µm (0.2 mm) in size., Light microscopes use glass lenses and visible, light and typically have a resolving power of 0.2, µm (0.2 . 10 – 6m). Resolution depends on the, wavelength of the illuminating light, but in general,, resolution is about 1000 times better than that of, an unaided human eye. Living or killed and fixed, cells may be viewed with light microscopes., Fossil studies indicate that cyanobacteria, bacteria, capable of photosynthesis, were among the earliest, bacteria to evolve, an estimated 3.4 billion to, 3.5 billion years ago. In the environment of the, early Earth, there was no oxygen, and, cyanobacteria probably used fermentation to, produce ATP. Over the eons, cyanobacteria, performed photosynthesis, which produces oxygen, as a byproduct; the result was the gradual, accumulation of oxygen in the atmosphere. The, presence of oxygen set the stage for the evolution, of bacteria that used oxygen in aerobic respiration,, a more efficient ATPproducing process than, fermentation. Some molecular studies of the, evolution of genes in archaebacteria suggest that, these organisms may have evolved in the hot, waters of hydrothermal vents or hot springs, slightly earlier than cyanobacteria, around 3.5, billion years ago. Like cyanobacteria,, archaebacteria probably relied on fermentation, to synthesize ATP.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚŇĐŕďňĚ, , 145, , Chapter 18, , Biomembrane, l, l, , l, , l, , l, , l, , l, , l, l, , l, , l, , All cells are enclosed by a thin, filmlike plasma, membrane or plasmalemma., The term “plasmalemma” was introduced by, Seifriz in 1928 later followed by J.Q. Plower, (1931)., This is also known as cell membrane (Nageli and, Cramer 1855) which is a component of the cell, surface and form the cell boundary., The other cell membranes includes the, –, nuclear envelope (encloses the nucleus), –, tonoplast (encloses the vacuole of plant cells),, and, –, the membranes of the various cell organelles, such as ER, Golgi apparatus, mitochondria,, chloroplasts and lysosomes., In prokaryotic cells, the membranes forms the, boundary of the cytoplasm being guarded from, outside by extracellular matrix and the cell walls., The plasma membrane and other intracellular, membranes surrounding the organelles and vacuoles, are collectively known as biological membranes., Historically, E. Overton (1895) was first to study, the structure or composition of plasma, membrane., Overton postulated that cell membrane is composed, of a continuous layer of lipid material., E. Gorter and F. Gredel (1925) studied RBCs of, a variety of mammals and proposed that the cell, membrane is formed of a bimolecular layer of, lipid sheet., Cells communicate with their environment by cell, membrane., Permeability is fundamental to the functioning, of the living cell and to the maintenance of, satisfactory intracellular physiological, conditions. This function determines which, substances can enter the cell, many of which may, , l, , l, , l, , l, , l, l, , l, , l, , be necessary to maintain its vital processes and the, synthesis of living substances. It also regulates the, outflow of excretory material and water from the, cell., The presence of a membrane establishes a net, difference between the intracellular fluid and the, extracellular fluid in which the cell is bathed. This, may be fresh or salt water in unicellular organisms, grown in ponds or the sea, but in multicellular, organisms the internal fluid, i.e., the blood, the, lymph, and especially the interstitial fluid, is in, contact with the outer surface of the cell membrane., One of the functions of the cell membrane is to, maintain a balance between the osmotic pressure, of the intracellular fluid and that of the, interstitial fluid., The plasma membrane is a semipermeable (not, every thing can pass through) boundary between, the cell and its external environment., Plasma membrane act as semipermeable because it, has the character of selective permeability means, that the cell membrane has some control over what, can cross it, so that only certain molecules either, enter or leave the cell while keeping other, constituents from escaping from the cell; and detects, and responds to the changes in the surrounding., The cell membrane is a fluid mosaic of lipids,, proteins and carbohydrates., Chemically a biomembrane consists of lipids, (2040%), proteins (5075%) and carbohydrates, (15%)., The main lipid components of the plasma, membrane are phospholipids, cholesterol and, galactolipids., The major proportion of membrane, phospholipids, is, represented, by, phosphatidylcholine, phosphatidylethanolamine,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 146, , l, , l, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , and sphingolipids (eg. sphingomyelin and, cerebrosides), all of which have no net charge at, neutral pH (i.e., neutral phospholipids) and tend to, pack tightly in the bilayer (This property is also, shared by cholesterol)., The lipid molecules are amphiatic or amphipathic,, i.e, they possess both polar hydrophilic (water, loving) and nonpolar hydrophobic (water, repelling) ends. The hydrophilic region is in the, form of a head while the hydrophobic part contains, two tails of fatty acids., Membrane proteins have been classified as, integral (intrinsic) or peripheral (extrinsic), according to the degree of their association with, the membrane and the methods by which they can, be solubilized., Integral proteins are generally transmembrane, proteins, with hydrophobic regions that completely, span the hydrophobic interior of the membrane., Proteins are much larger than lipids and move more, slowly, but some do drift., Peripheral proteins are not embedded in the lipid, bilayer at all; they are loosely bound to the surface, of the membrane, often to the exposed parts of, integral proteins., Proteins can be fibrous or globular, structural,, carrier, receptor or enzymatic. About 30 kinds of, enzymes have been recorded in different, biomembranes, e.g., phosphatases, ATPase,, esterases, nucleases, etc., Carbohydrates present in the membrane are, branched or unbranched oligosaccharides, e.g.,, hexose, fructose, hexoamine, sialic acid, etc., Some of these oligosaccharides are covalently, bonded to lipids, forming molecules called, glycolipids. Most are covalently bonded to proteins,, which are thereby glycoproteins., The biomembranes are asymmetric i.e the two, surfaces of biomembrane are not similar because –, –, Lipids present in both the layer are different,, eg, lecithin on outer side and cephalin on inner, side of erythrocyte membrane., –, Extrinsic proteins are more abundant on inner, side than on the outer surface., –, Oligosaccharides, attached to external surface, of lipids and proteins, are absent on the inner, side., , ULTRASTRUCTURE OF, PLASMAMEMBRANE, l, , l, , Under electron microscope the plasma membrane, appears three layered, ie., trilaminar. One optically, light layer is of lipids and on both sides of it two, optically dense layers of proteins are present., Three important models explaining the, ultrastructure of plasma or cell membrane are–, –, Danielli Davson model : Bilayer model., –, Robertsonian : Unit membrane concept, –, Singer and Nicolson : Fluid mosaic model., , Bilayer model by Davson & Danielli, l, , l, l, , l, , Danielli and Davson proposed that the plasma, membrane is made up of three layers : a, biomolecular layer of lipid sandwiched between, two layers of proteins., Danielli and Davson model is the oldest model on, the structure of plasma membrane., The inner ends and lipid molecules are hydrophobic, and nonpolar while the outer ends are hydrophilic, and polar., Proteins are attached at the outer ends of lipid layer, (hydrophillic ends) by ionic exchanges and, hydrostatic forces., , Unit membrane model by Robertson, l, , l, , l, , l, , l, , Based upon electron microscopy on myelin,, Robertson in 1959 proposed his famous ‘unit, membrane concept’., Robertson called it as a ‘unit membrane’ because, the pattern of molecular organization was same for, all membranes., According to Robertson the thickness of lipid, biomolecular layer is 3.5 nm, each protein layer, 2.0 nm, making up a total thickness of 7.5 nm (75Å)., One of the major weaknesses of Robertson’s, model was its failure to explain permeability and, transport properties of the membrane., It has been well established that in plasma, membrane proteins are of two types –, –, Extrinsic proteins are peripheral proteins,, associated with the surface., –, These can be easily removed, eg., spectrin in, red blood cells and ATPase in mitochondria., –, Intrinsic proteins or Integral proteins – enter, the lipid bilayer and extend all the way through, it, eg., rhodopsin in retinal rod cells.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚŇĐŕďňĚ, , –, , The portions of the polypeptide chains that, extend through the lipid bilayer typically occur, as ahelices composed of hydrophobic amino, acids., , Fluid mosaic model by Singer & Nicolson, l, , l, l, , l, , l, l, , l, l, l, , l, , l, l, l, , l, l, , The most universally accepted “fluid mosaic, model” of structure of plasma membrane was, proposed in 1972 by S. Jonathan Singer of, University of California and Garth Nicolson of, the Salk Institute., Singer and Nicolson took the help of freeze, fracture techniques in electron microscopy., According to fluid mosaic model, the membrane, contains a biomolecular lipid (2 dimensional, liquid), layer, the surface of which is interrupted by proteins., Some proteins are attached at polar surface of lipids, called the peripheral or extrinsic proteins and the, other proteins, which penetrate the bilayer or span, membrane entirely are called the integral, transmembrane or intrinsic proteins., The integral proteins form about 70% of the total, membrane protein., The extrinsic proteins may be covalently attached, to fatty acids chains or noncovalently attached, to other transmembrane proteins., The transmembrane proteins extends through the, bilipid layer as a single helix (eg, glycophorins)., The proteins on the outer side may bear chains of, sugar forming glycoproteins., The three major types of membrane lipids are, phospholipids, cholesterol and glycolipids. These, lipids are amphiphatic., Cholesterol becomes intercataled between, phospholipids in membranes and increases the, stability of the bilayers and prevents the loss of, membrane liquidity at low temperature., The proteins may float freely like icebergs., The lipids act as a barrier to the entry or exit, of charged polar substances., Some proteins in the plasma membrane act as, “gatekeepers” that regulate the traffic of molecules, and ions into and out of the cell., Selective permeability of plasma membrane can, be explained with the help of fluid mosaic model., Plasma membrane is composed mainly of protein,, lipid and a small percentage (1–5) of, carbohydrates., , l, l, l, l, l, , 147, , The carbohydrates of plasma membrane are hexose,, hexosamine, fructose and sialic acid., Carbohydrates present in plasma membrane are in, the form of glycoproteins and glycolipids., Lipids and intrinsic proteins form a mosaic pattern., The membrane is semifluid in nature and hence the, lipid molecules and intrinsic proteins move freely., Such membranes are also present around different, cell organelles, eg. mitochondria, Golgi bodies,, endoplasmic reticulum, etc., , SPECIALISATION OF PLASMA, MEMBRANE, l, , l, , l, , l, , l, , l, , l, , l, , The term ‘coenocyte’ is used to describe the, multinucleate condition in which cell membrane is, lacking between cells., The concept of membrane fluidity refers to the, fact that both lipids and proteins may have, considerable freedom of lateral movement within, the bilayer., The fluidity of the membrane can be studied with, a series of techniques that can be classified as, physical or biological., The physical techniques are of two main types :, (1) those that involve a minimal perturbation of the, membrane, such as Xray diffraction and nuclear, magnetic resonance (NMR) spectroscopy; and (2), those that use certain added molecules to monitor, specific sites of the membrane. Into this second, class fall fluorescence microscopy, which uses, fluorescent probes, and electron spin resonance, (ESR) spectroscopy, which uses paramagnetic, probes (e.g., nitroxidecontaining amphipathic, molecules) that are introduced into the lipid bilayer., The biological techniques involves light and, fluorescence microscopy and electron microscopy,, including freeze fracturing and radioisotope, labelling methods., Several factors that influence membrane fluidity, are: temperature; percentage of unsaturated tails;, and the presence of cholesterol., Fluidity increases with rise in temperature and, decreases with lowering of temperature., Membrane fluidity is essentially a property of the, lipids., Normally these are fluid at body temperature and, the main consideration is the degree of saturation, of the hydrocarbon chains.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 148, , l, , l, , l, , l, , l, , l, l, l, , l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , As temperature decreases, a critical temperature is, reached at which the membrane solidifies. At this, temperature, the tails of the phospholipids are, packed tightly together and movement is inhibited., One factor that tends to increase rigidity is the, concentration of cholesterol. The steroid, cholesterol, which is wedged between phospholipid, molecules in the plasma membranes of animals, helps, stabilize the membrane. At relatively warm, temperatures, for example, 37°C, the body, temperature of humans, cholesterol makes the, membrane less fluid by restraining the movement of, phospholipids. However, because cholesterol hinders, the close packing of phospholipids, it also lowers, the temperature required for the membrane to solidify., Rapid changes in fluidity can be produced by, methylation of phosphatidylethenalomine by, methyltransferases present in the membrane., These inturn are regulated by receptors. This has, been confirmed by a simple but ingenious, experiment devised by Frye and Edidin (1970)., L.D. Frye and M. Edidin (1970) provided, evidence for the mobility of membrane proteins, obtained by fusing mouse and human cells to form, heterokaryons., Before fusion, they labelled mouse cells with green, fluorescent antibody dye fluoroscein and human, cells with red fluoroscent antibody dye rhodamine., The frequency of cell fusion could be greatly, increased by adding Sendai virus., Cell membrane modified into foldings,, intercellular junctions and extracellular coats., Infolds (invagination) facilitate pinocytosis (cell, drinking) and phagocytosis (cell eating) which, together constitute endocytosis., Invagination results in the formation of pores,, mesosomes, lomasomes and transfer cells., Cellcell junctions play an important role in cell, cell adhesion and in intercellular transport., The most common types of junctions are –, –, Tight junctions (zonula occludens), –, Intermediate junctions (belt desmosomes), –, Spot desomosomes (macula adherens), –, Gap junctions (connexons or nexuses), –, Plasmodesmata, Extracellular coats formed in animal cells are of, following types – chitin, glycocalyx, basement, membrane, cell wall etc., , TRANSPORT ACROSS BIOMEMBRANE, l, , Membranes are selectively permeable. The, different methods of transport across the cell, membrane consists of: passive transport, active, transport, bulk transport., , Passive transport, l, , l, l, , l, l, , l, , l, , l, , l, , l, , l, , l, , Passive transport is a mode of membrane transport, where the cell does not spend any metabolic, energy., This transport is according to the concentration, gradient., Passive transport is of following types – diffusion, (simple diffusion), facilitated diffusion and, osmosis., Simple diffusion can occur either through lipid, matrix of the membrane or with the help of channels., In faciliated diffusion some specific solutes diffuse, down electrochemical gradients across membrane, more rapidly than might be expected from size or, charge., Facilitated diffusion occurs through the agency of, special membrane proteins (called carrier proteins, which is also known as permeases), but like simple, diffusion, it requires no metabolic energy., Osmosis (discovered by Albe Nollet, 1748) is the, net movement of a solvent through a selectively, permeable membrane., In living systems, the solvent is water, which moves, by osmosis across plasma membranes from an area, of higher water concentration to an area of lower, water concentration., In osmosis, water moves through a selectively, permeable membrane from an area of lower solute, concentration to an area of higher solute, concentration., The water potential of a solution is the term given, to the tendency for water molecules to enter or, leave that solution by osmosis., Water potential is a term derived from, thermodynamics, and is a measure of the free, kinetic energy of the water molecules in the, solutions., Two important factors which determine the, water potential of solutions in and around living, cells are– the presence of dissolved solutes (giving, rise to a solute potential) and the mechanical, pressure acting on water (pressure potential).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚŇĐŕďňĚ–, l, , l, , l, , l, , l, l, l, , l, l, , l, , l, , l, , l, l, , l, , Osmotic pressure is the maximum pressure which, can develop in an osmotically active solution when, it is separated from its pure solvent by a, semipermeable membrane under ideal conditions., The solute potential of a concentrated solution can, be demonstrated dramatically in an apparatus known, as an osmometer., Tonicity is the amount of tension developed in a, system on account of the occurrence of solute, particles in it. It is usually determined in comparison, to other systems or solutions., When two solutions are compared for their osmotic, pressure or concentration, one may have higher, concentration than the other or the two may have, the same concentration., On the basis of tonicity, solution are of three, types – hypertonic, hypotonic and isotonic., Tonicity determines exosmosis and endosmosis., Hyperosmotic (hypertonic) solutions will cause, water to leave cells by osmosis, and cells may, shrink (in animal cells, membrane collapses or, becomes crenated and in plant cell, shows, plasmolysis)., Hypertonic solution has higher proportion, (concentration) of solutes., Hypoosmotic (hypotonic) solutions will cause, water to enter cells by osmosis, causing the cells, to swell and burst in animal cell and becomes, turgid in plant cells., In hypotonic, the external solutions has a lower, solute concentration (more water) than the internal, solution of the cells., Isotonic solutions will have equal proportions, of solutes to water on both sides of the, membrane., Isoosmotic solutions are osmotically balanced and, there is no net movement of water. Water will, move through the membrane, but equal amounts of, water will be moving in both directions., Types of osmosis are– endosmosis and exosmosis., Endosmosis is the process of osmotic entry of, solvent or water into a cell or system when it is in, contact with hypotonic solution or pure solvent., Endosmosis is best seen by placing raisins in water., Exosmosis is the outflow or exit of solvent or water, from a cell or system when the same is kept in, contact with hypertonic solution. Exosmosis is best, seen when sliced cucumber is sprinkled with salt., , l, , 149, , Exosmosis causes plasmolysis in plant cells., , Active transport, l, , l, , l, l, l, , l, l, l, , l, , The active transport is the transport of ions or, molecules against their concentration gradient or, electrochemical gradient., Active transport differs from diffusion in that, molecules are transported away from thermodynamic, equilibrium, hence energy is required., This energy can come from the hydrolysis of ATP,, from electron movement or from light., Two main types of active transport are : primary, active transport and secondary active transport., In primary active transport, energy is provided, by another coupled reaction such as the hydrolysis, of ATP., Sodiumpotassium exchange pump is an example, of primary active transport., For each molecule of ATP used, three Na+ ions are, pumped out and two K+ ions are pumped in., The Na+ gradient established by the Na+ – K+ pump, provides a source of energy that is frequently used, to power the active transport of sugars, amino acids, and ions in mammalian cells., A secondary active transport takes place with the, help of ion gradient from the coupled transport of, a second molecule., , Bulk transport, l, , l, l, l, , l, l, , l, l, , Bulk transport is the transport of large quantities, of macromolecules, micromolecules and food, particles through the membrane., Bulk transport occurs by two main methods,, endocytosis and exocytosis., Bulk transport involves the enclosure of the material, under transport in carrier vesicles of the membrane., The inward transport of carrier vesicles is called, endocytosis and outward transport of carrier, vesicles is called exocytosis., The bulk transport is common in excretory and, secretory cells., When cells engulf extracellular substances and bring, them to the cytoplasm in membrane bound vesicles, it is called endocytosis., Endocytosis occur by pinocytosis, phagocytosis, and receptor mediated endocytosis., Phagocytosis (Gr. phagein, to eat, kytos, cell) is a, process whereby certain cells and unicellular, organisms are capable of ingesting and digesting, solid material.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 150, , ŕďőĽę– ĐĽŐńŐĹť, , Covers, , Allows certain inorganic salts, nutrients, water and other metabolites, to pass into the cell and permit the, Cell organelles – called subcellular release of cellular waste products, membranes, and other specific molecules., Invagination, – Facilitates cell drinking and cell eating, Foldings, – Occurs by forming pores, endocytotic vesicles,, mesosome, lomasomes etc, Cell – called plasma membrane, , Modification, , Biomembranes, , Evagination, – Occurs by microvilli, stereocilia, interdigitations, , Intracellular, junctions, – interdigitation, – tight junctions, – gap junctions, – plasmodesmata, – desmosomes etc, , Extracellular coats, Chitin, glycocalyx, basement membrane, cell wall., , Models, – Lipid model by Overton (1900) and Gorter and Grendal (1926), – Bilayer model by Danielli and Davson (1930’s), – Unit membrane concept by Robertson (1959), – Fluid mosaic model by Singer and Nicolson (1972), Transport across, cell membrane, Diffusion, • Fat soluble substances pass through biomembranes, Active transport, • Operates in any medium, (see on next page), Facilitative Diffusion, Passive transport, Passage of substances along the concentration gradient without, (Do not need energy), expenditure of energy with the help of membrane transport protein, Bulk transport, (see on next page), , Osmosis, • Diffusion across a semipermeable membrane, • Operates only in liquid medium, , Types, Exosmosis, , Endosmosis, , Causes, Plasmolysis, shrinkage of protoplast of cell from its cell, wall under the influence of hypertonic solution, , When shrinkage stops at, particular stage then there is, no further decrease in size, , Occur in three stages, Ist Incipient (just starting to happen) plasmolysis, IInd Evident plasmolysis, IIIrd Limiting (the ultimate extent) plasmolysis, , Called, Limiting, plasmolysis, , Flowchart : Biomembrane at a glance, , Causes, Deplasmolysis, Swelling of plasmolysed protoplast, under the influence of hypotonic, (low salt concentration) solution or, water
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 151, , ▲ĽŐŇĚŇĐŕďňĚ, , Transport across cell membrane, , Active transport, Required energy and takes place, against concentration gradient, , Bulk transport, Transport of large quantities of micromolecules,, macromolecules and food particles through the, membrane, , Takes place through, , Carrier proteins, Integral protein particles, which have affinity for, specific solutes, Form, , Carrier solute complex, Undergoes, Conformational changes, To transport the solute, , Occur by, , Gated channels, Opens by either change in, electrical potential or, specific substance, +, +, Eg. (1) K –H exchange, pump (in guard cells), +, +, (2) Na –K exchange, pump (in animal, membranes), , Exocytosis, Transport of material out of cells, , Operate with, the help of, ATP, , Reverse pinocytosis, , Used to throw solids, undigested, waste and other materials, Eg, excretion in Amoeba,, secretion of hormones by cells., , Endocytosis, Transport of material, into the cell, , Occur by, , Phagocytosis (cell eating), • Eg, lysosomes, phagocytes,, Amoeba for engulfing food., Leucocytes to remove dead, bacteria and germs, • Material taken up in the solid, form, • Generally a large vacuole, • Used to engulf germs, bacteria, or other large particles., , Pinocytosis (cell drinking), • Eg, Amoeba, liver cells, amoeboid, cells., • Materials taken up in liquid form, • Generally small vesicles., • Used to take secretions like lipo, proteins or food like, macromolecules in liquid form., (generally the macromolecules that, cannot enter through the plasma, membrane are taken in this way)., , Receptor mediated endocytosis, , • Process by which cell, , internalize m olecules or, viruses. It depends on the, interaction of that molecule, with a specific binding, protein in the cell membrane, called a receptor.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 152, , l, l, , l, , l, l, l, l, , l, , l, l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , The term phagocytosis has been coined by a Russian, scientist Ilie Metchnikoff in 1893., For the description of phagocytosis Metchnikoff, got Nobel prize of Physiology and Medicine in, 1908., Phagocytosis is done by the cell extending, pseudopodia which encircle and engulf it into, membrane delimited vesicles called phagosomes., The term pinocytosis (Gr. pinein, to drink) was, coined by Lewis in 1931., Lewis was the first to observe pinocytosis in living, cells in culture., Pinocytosis (also called cell drinking) is quite, common in the cell lining the blood capillaries., Lewis described the uptake of fluid matter and, substances dissolved in it (eg ions, sugars, amino, acids) by an active movement of undulating, membrane formed at the periphery of the cell., Mast and Doyle using fluorescence microscopy, indicated that pinocytosis may be important for the, cellular uptake of proteins., A receptor mediated selective process is known as, absorptive pinocytosis., The vesicles formed during absorptive pinocytosis, are derived from invaginations (pits) that are coated, on the cytoplasmic side with filamentous material, like clathrin., The signal for exocytosis is often a hormone which,, when it binds to a cell surface receptor, induces a, local and transient change in Ca2+ concentration., Ca2+ triggers exocytosis., Exocytosis (the reverse of endocytosis) causes, expulsion of materials from the cells., In plant cells, exocytosis is an important means of, , l, , exporting the materials needed to construct the cell, wall through the plasma membrane., Among protists, contractile vacuole discharge is a, form of exocytosis. In animal cells, exocytosis, provides a mechanism for secreting many hormones,, neurotransmitters, digestive enzymes, and other, substances., , FUNCTIONS OF BIOMEMBRANES, l, , l, , l, l, , l, l, l, , The most important function of plasma membrane, is to provide passage for various substance, into, and out of the cell., Plasma membrane is selectively permeable, ie.,, allows some solute particles (1–15 Å) to pass, through it readily along with all solvents., It not only provides mechanical strength but also, acts as a protective layer., Plasma membrane is responsible for the, transportation of materials, molecules or ions, etc.,, through it., Anchoring of the cytoskeleton to provide shape to, the cell., Attaching to the extracellular matrix to help group, cells together in the formation of tissues., The plasma membrane takes part in cellular, locomotion in two ways : pseudopodia and, undulation., –, In pseudopodia Amoeba, macrophages and, WBCs move with the help of temporary, locomotary organelles like pseudopodia., –, In undulation some mammalian cells such as, fibroblasts can move over a solid surface by, wave like undulations of the plasma, membrane.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń, , 153, , Chapter 19, , Structural Organization of Cell, l, , l, l, , l, l, , Cell are the smallest structural and functional, units of life (and of diseases processes) in all tissues,, organs and organ system., A cell has a variety of molecules, often called, biomolecules, in it., A biomolecules may occur in solution, or in, colloidal state in the cell, or may be assembled into, subcellular components of the cell., The subcellular components are often called as cell, organelles, that is small organs., Organelles are membrane bound, enzyme, containing subcellular compartments (eg, , l, , l, l, , mitochondria). Each type of organelles has a, distincting structure and performs unique functions., Cell include plasma membrane, endoplasmic, reticulum, ribosomes, Golgi apparatus, lysosomes,, microbodies, mitochondria, plastids, microtubules,, microfilaments, intermediate fibres, centrioles,, basal bodies, cilia, flagella, vacuoles and nucleus., The entire protoplasm of a cell is known as, protoplast., Protoplast has four components – plasmalemma, (or plasma membrane), cytoplasm, nucleus &, vacuole., , Cell, Cell wall &, Vacuole (in plant cell only), Plasma membrane (in plant), , Protoplasm, Nucleus, , Cytoplasm, , Metabolically inactive substances, Metabolically active organelles, (or Cytoplasmic inclusions or Ergastic substances, (or cytoplasmic organelles), or Deutoplasmic substances or Deutoplasm), 1) Mitochondria, 2) Plastids, 3) Endoplasmic reticulum, 4) Golgi bodies, 5) Ribosomes, Storage substances Secretory substances Excretory substances, 6) Centrosomes, eg., carbohydrates, eg., colouring matter,, eg., glucosides,, 7) Microbodies, fats, proteins, enzymes, nectar, tannins, gums,, (i e. Lysosomes,, etc, etc, resins, etc., Perioxisomes, etc.), , Flow chart – Organization of cell, , PLASMA MEMBRANE, l, , The cell membranes separate a cell from its, environment and form distinct functional, compartments (nucleus, organelles) in the cell. The, outer cell membrane is called the plasma, membrane or plasmalemma., , l, , l, , (For more details on plasma membrane refer, chapter Biomembrane), In the cells of bacteria, cyanobacteria, protists, fungi, and plants, a thick, rigid, protective but porous coat,, the cell wall, outside the plasma membrane is found., The composition of cell wall varies in different groups.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 154, , l, , l, , l, l, , l, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Composition of cell wall, –, In plants, cell wall is made up of cellulose, (bDglucose units), hemicellulose (arabinose,, mannose, xylose, galactose, etc.) and pectin, (galactose, galacturonic acid and arabinose), –, In bacteria, cell wall is composed of protein, lipidpolysaccharides having two important, chemical components: Nacetyl glucosamine, (NAG) and Nacetyl muramic acid (NAM)., –, In fungi, cell wall is made up of chitin, (polymer of Nacetyl glucosamine)., –, Algal cell wall contains cellulose and a variety, of glycoproteins., One of the most important differences between, plant and animal cells is the presence of a cell, wall (nonliving protective layer) in plant cells., Cell wall was first discovered in the cell by Robert, Hooke in 1665., Cell wall is absent in animal because cell wall is, incompatible with the way in which an animal, moves and grows., In an animal cell and many protists, cell membrane, are covered by filamentous layer (also called cell, coat) of an oligosaccharide sialic acid (called, glycocalyx), which protects the underlying, membrane and helps in recognition of the cells, (by Wilson, 1907)., Recognition ability is mainly due to Ca2+ and Mg2+, absorbed over glycocalyx., The cell coat of glycocalyx may be supported and, strengthened by deposition of calcium salts, silicon, or other substance., A typical cell wall is made up of 4 layers – middle, lamella, primary, secondary and tertiary wall., Middle lamella is the cementing layer between, the cells. It is made up of Ca & Mg pectates., The ripened fruits becomes softened due to, dissolution of middle lamella. It can be done, artificially by spraying strong acids., , l, , Primary cell wall, –, It is formed in a growing cell., –, It is laid down on both sides of middle lamella., –, It is present in all plant cells., –, It is elastic and capable of expansion in a, growing cell., –, It grows in thickness by intussusception., –, It consists of a single layer of wall material., –, It is 1–3 mm thick., , –, , l, , l, , l, , l, , l, , l, l, , Its cellulose macrofibrils are short, wavy and, loosely arranged., –, It lacks pits and additional materials., –, Its water content is about 60%., –, It has relatively low cellulose content., –, It has high hemicellulose, protein and lipid, contents., Secondary cell wall, –, It is formed in a mature cell., –, It is laid down on the inner side of primary, wall after the growth of cell stops (at maturity)., –, It is present in certain plant cells only, for, eg. gymnosperms., –, It is rigid and nonelastic and incapable of, expansion., –, It grows in thickness by accretion., –, It consists of 3 or more layers of wall material., –, It is 5–10 mm thick., –, Its cellulose macrofibrils are long, straight,, compactly arranged., –, Its water content is about 30–40%., –, It has relatively high cellulose content., –, It has relatively low hemicellulose, protein,, and lipid contents., Sometimes tertiary wall is laid down on secondary, wall, e.g., tracheids of gymnosperms. It is purely, cellulosic in nature., The cell wall is not uniform in thickness throughout;, at certain places secondary wall or both primary, and secondary walls are not laid down. Such places, are called pits., Pits are of two types – simple pit in which pit, chamber is uniform in diameter, and bordered pit, in which pit chamber is flaskshaped in tracheids, of gymnosperms and vessels of angiosperms., A number of plasmodesmata or cytoplasmic, strands are present in pit through which the, cytoplasm of one cell is in contact with another., Endoplasmic reticulum plays a role in origin of, plasmodesmata., Origin of cell wall takes place from cell plate during, cytokinesis. Many cell wall vesicles provided by, Golgi bodies and endoplasmic reticulum combine, to form a cell plate. After some chemical and, physical changes, the cell plate grows on both sides, to form a middle lamella. Primary and secondary, walls are laid down on middle lamella to form cell, wall. Beside these, different materials are deposited, as – lignin, suberin, cutin, silica and mucilage.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 155, , ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń–, l, , l, , l, , l, , l, , l, l, l, l, , Lignin is special type of polysaccharide which, deposits mainly in xylem cells and makes them hard, and lignified. Due to its deposition xylem tracheids, take up different forms, e.g., annular thickening,, spiral thickening, scalariform thickening., Suberin is a complicated mixture of fatty acids, deposited on cork cells. Suberin is impermeable to, water., Cutin is a waxlike fatty substance. It is deposited, on the epidermal cells in the form of cuticle which, reduces loss of water. Cuticle is very thick in, xerophytes, thin in mesophytes and absent in, hydrophytes., Silica In some cases sand or silica particles are, deposited which give a rough touch, e.g., Equisetum, and Saccharum munja., In family Moraceae, Urticaceae, Cucurbitaceae and, Acanthaceae, Ca oxalate and Ca carbonate crystals, are deposited., Mucilage: Some cells are slippery to touch due to, secretion of mucilage, e.g., bluegreen algae. The, cells can withstand extremes of temperature, i.e.,, very low or very high., After maceration it has been found that cell wall, consists of fibrils and gel like matrix., The macrofibrils consists of bundle of microfibrils, which in turn consists of bundle of micelles., The matrix consists largely of polysaccharides. It, also contains polygalacturonic acid and xylans., Functions of cell wall are –, –, It maintains shape of the cells., –, It protects the cell from mechanical injury., –, It wards off the attack of pathogens (viruses,, bacteria, fungi, protozoans)., –, It provides mechanical support against gravity., –, The cell wall prevents undue expansion of the, cell when water enters by osmosis to, compensate for the lack of contractile vacuole., This prevents bursting of cells., –, It allows the materials to pass in and out of the cell., –, Though permeable, the cell wall plays some, regulatory role on the passage of materials, into and out of the cell., –, Growth of the cell wall enables the cells to, enlarge in size., –, The wall in some cases has a role in defence, and offense by means of spines., , CYTOPLASM, l, l, , l, , l, , l, l, l, , l, l, , The cytoplasm surrounds the nucleus and is, enclosed by the plasma membrane., Cytoplasm, a jelly like substance (called cytosol or, hyaloplasm or cytoplasmic matrix) and composed, of mainly water is found between the cell, membrane and nucleus., Cytoplasm contains the structures and substances, needed to decode the instruction of DNA and carry, on the activities of the cell., Autonomic movement of matrix in the cytoplasm, in a cell is called cytoplasmic streaming or, cyclosis., Cytoplasm exists in two states – sol (plasmasol), and gel (plasmagel)., Sol or hydrol is a liquid colloidal solution where, the colloidal particles are well dispersed in water., Gel is a thick semi – solid colloidal system in which, the colloidal particles come in contact and form a, sort of network with water dispersed in the meshes., Only the sol part of the cytoplasm shows, cyclosis., Cytoplasmic structures comprises 3 groups –, cellorganelles, cytoplasmic inclusions, and, cytoskeleton., , Cell organelles, l, l, l, l, l, , l, l, , These are regarded as living structure of a cell., They are capable of growth, some may divide also, and form metabolic machinery of a cell., These are formed in the cell itself., Eukaryotic cells are far more complex than, prokaryotic cells., Both animal and plant cells share the same features, but plant cells usually have the following feature, in addition – cell wall (described earlier), vacuole, and chloroplast., While centrioles, basal bodies and flagella are present, in animal cells and are lacking in plant cells., The type of organelles are – ER, golgi complex,, lysosome, mitochondria, ribosomes, microbodies,, cytoskeletal structures, flagella and cilia etc., , Endoplasmic reticulum (ER), l, The ER was first noted by Porter, Claude and, Fullman in 1945 as a network. It was named ER, by Porter in 1953., l, It is absent in prokaryotes but present in all the, eukaryotes except germinal cells and mature, mammalian erythrocytes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 156, , Ø, , Ø, Ø, , Ø, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Structures formed by ER, Sphaerosomes. Sphaerosomes (= spherosomes) are small cell organelles bounded by single membrane, which take part in storage and synthesis of fats. They were discovered by Perner in 1953. Sphaerosomes, are small spherical and refractile vesicles which are 0.51.0 mm in diameter. 98% of a sphaerosome is fat., Proteins constitute the remaining 2%. Some proteins are probably enzymatic and take part in the synthesis, of fats. Because of the presence of fat, sphaerosomes can be seen under light microscope after staining the, cells with Sudan dyes and osmium tetraoxide. Sphaerosomes occur abundantly in the endosperm cells, of oil seeds. Sphaerosomes of some tissues (e.g., tobacco endosperm, maize root tip) contain hydrolytic, enzymes. Therefore, they are considered to have lysosomic activity., Ergastoplasm. The term ergastoplasm used for the specialised ER with ribosomes. Furthermore they show, special staining and cytochemical properties and may be connected with the ER., Myeloid bodies. Another kind of specialized endoplasmic reticulum (SER) which are found in the pigmented, epithelial cells of retina. Ribosomes are not found attached to them. It consists of vesicles and tubules near the, basement membrane of the cell so they acts as photoreceptors of the cells., Microsomes. Microsomes are the fragments of RER. It may also derived from the plasma membrane., They are formed as a result of fragmentation of cells. Microsomes derived from RER have ribosomes, attached to outside. It should be noted that they are not found in the intact cell, i.e. they are not the natural, cell structures., Development of ER depends upon the metabolic, state and stage of differentiation of the cells, e.g.,, absent from embryonic cells, less developed in, spermatocytes (only a few vesicles) and well, developed in fully differentiated and metabolically, active cells (e.g., pancreas, liver, etc.) and simple in, storage cells (in the form of tubules in adipose cells)., The striated muscle fibres have a special type of, ER called sarcoplasmic reticulum (SR)., ER is a welldeveloped electron microscopic, network of interconnected cisternae, tubules and, vesicles present throughout the cytoplasm,, especially in the endoplasm., Cisternae are flattened, unbranched, saclike, elements. The sacs in the stack are interconnected, with one another. They bear ribosomes on the, surface that makes the cisternae appears rough., The cisternae contain glycoproteins named, ribophorinI and ribophorinII that bind the, ribosomes., Tubules are tubelike extensions which may be, connected with cisternae or vesicles to form a, reticular system. The tubules can be irregular or, regular, branched or unbranched with a diameter of, 50100 nm often free of ribosomes., Vesicles are oval or rounded, vacuolelike elements, 25500 nm in diameter. They often occur isolated in, the cytoplasmic matrix. They are also free of, ribosomes. They are often called microsomes., , l, , l, , l, l, , l, , l, , l, l, , The endoplasmic reticulum (ER) is a complex, organelle, involved in the synthesis, packaging, and processing of various cell substances., The ER membranes actually attach to the cell, membrane and the nuclear membrane as well as, golgi bodies in the cytoplasm., In mature cells, ER occurs in 2 forms – rough, (RER) and smooth (SER)., The fine structure of RER (membranes and, individual ribosomes) is visible only with the, electron microscope., RER (consists mainly of cisternae) is mainly, concerned with the synthesis of proteins for, sequestration from the rest of the cytoplasm, i.e.,, secretory proteins such as collagen, proteins for, incorporation into cell membrane, and lysosomal, enzymes (separated from the rest of the cytoplasm, to prevent autolysis)., The smooth endoplasmic reticulum (SER) lacks, ribosomes and thus appears smooth in electron, micrographs., SER cisternae are more tubular or vesicular than, those of the RER., SER has many enzymes, important in lipid, metabolism, steroid hormone synthesis, glycogen, breakdown (glucose6phosphatase) and, detoxification. The last occurs via enzymatic, conjugation, oxidation and methylation of, potentially toxic substances.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń–, , SER is also abundant in liver cells (hepatocytes),, where it is involved in glycogen metabolism and, drug detoxification., l, Functions of ER are –, –, Facilitates transport of materials from one part, of the cell to another, thus forming the cell’s, circulatory system., –, Detoxification of drugs, –, associated with muscle contraction by release, and uptake of Ca2+ ions, –, Help in formation of primary lysosome with, hydrolytic enzymes., –, Helps in the synthesis of nuclear envelope, during telophase of cell division., –, Provides space for temporary storage of, synthetic products such as glycogen., Golgi complex, l, Golgi complex (Golgi apparatus or dictyosome), participates in many activities, particularly those, associated with secretion., l, In animal cells Golgi complex or apparatus is either, single or consists of a single connected complex., The two conditions are respectively called localized, (most vertebrate cells) and diffused (most, invertebrate cells, liver and nerve cells of vertebrates)., The localized organelle is compact. It generally, occurs at one end between the nucleus and the, periphery. The diffused organelle is found to form, a network, e.g., around the nucleus in nerve cells., l, In plant cells Golgi apparatus is formed of a number, of unconnected units called dictyosomes. Their, number is highly variable—from one in certain, simple algae to 25000 in rhizoidal cell of Chara., l, A liver cell may possess upto 50 units of Golgi, apparatus called Golgisomes., l, , l, , l, , l, , l, , l, l, , 157, , This membranous organelle comprises 3 major, compartments : (1) a stack of 310 discrete, slightly, curved, flattened cisternae; (2) numerous small, vesicles peripheral to the stack; and (3) a few large, condensing vacuoles at the concave surface of the, stack., Products synthesized by the ER are packaged in, vesicles by the Golgi complex. These secretory, vesicles, or secretory granules, are transported to, the plasma membrane for exocytosis., Golgi complexes are best developed in neurons, and glandular cells, which are specialized for, secretion., Golgi apparatus is named from Camillo Golgi who, discovered it in 1898 in the nerve cells of barn owl, and cat by means of metallic impregnation method, (i.e osmium chloride + silver salts)., The golgi apparatus is the processing, packaging, and secreting organelle of the cell., Functions of Golgi apparatus are –, –, A variety of enzymes are localized in the Golgi, complex to help in the cell’s biochemical, reaction., –, Absorbs materials from the environment., –, Lipids and proteins coming from the ER are, complexed into lipoproteins in the Golgi, apparatus. This process is liposylation., –, Golgi apparatus links carbohydrates with, protein coming from ER to form glycoproteins., This process is glycosylation., –, Formation of nematocytes (in Hydra) and, trichocysts (in Paramecium)., –, Formation of acrosome, an important, constituents of the tip of animal sperms., , Table : Functions of golgi complex in different types of cells, 1., 2., 3., 4., 5., 6., 7., 8., 9., , Cell type, Exocrine cells of pancreas, Goblet cells of intestinal mucosa, Paneth cells of intestine, Brunner’s gland cell or duodenum and, ileum, Hepatic cells of liver, Follicle cells of thyroid gland, Plasma cells of blood, Cells of alveolar epithelium of mammary glands, Plant cells, , Golgi functions, Secretion of zymogen (digestive enzymes – protease,, lipase carbohydrates and nucleases)., Secretion of mucus and zymogens., Secretion of proteins., Secretion of mucopolysaccharides., Transformation and secretion of lipids., Prothyroglobulins (hormone)., Immunoglobulins (hormone)., Secretion of milk proteins., Secretion of protein and cellulose.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 158, , –, , ŕďőĽę– ĐĽŐńŐĹť, , In plant cells, synthesizes pectin and some, other carbohydrates, necessary for the, formation of cell walls etc., Lysosomes, l, The lysosomes are noticeable with electron, microscope only., l, The lysosomes were first reported by a Belgian, cytologist and biochemist Christian de Duve in, 1955., l, In 1956, Novikoff observed lysosomes in the cell, with electron microscope and coined the term, lysosome., l, Lysosomes are common in the cell of animals, fungi, and protista, but rare in plant cells., l, In animals, lysosomes are abundant in leucocytes,, macrophages, Kupffer’s cells and similar cells, with phagocytic activity, prokaryotes lack, lysosomes., l, Lysosomes are spheric, single membranelimited, vesicles (produced by golgi apparatus) that may, contain more than 50 enzymes each and function, as the cellular digestive system., l, Lysosome is also known as suicidal sac/bag as, they contain hydrolytic enzymes., l, At pH 4.8 the interior of the lysosomes is more, acidic than the cytosol pH 7., l, The important enzymes are – acid phosphatases,, sulphatases, proteases, nucleases, lipases and, glycosidases. They are also called acid hydrolases, because these digestive enzymes (usually occur as, glycoproteins) usually function in acidic medium, or pH less than 7., l, The covering membrane of lysosomes keeps the, hydrolytic enzymes out of contact from the cellular, contents. The covering membrane becomes fragile, in the absence of the oxygen, or the presence of, excess of vitamins A and E, male and female, hormones, bile salts, Xrays and ultraviolet rays., These are called membrane labilizers., l, These labilizer cause instability of the lysosomal, membrane, leading to release of enzymes from, the lysosomes., l, The membrane is protected from these agencies, by cortisone, cortisol, chloroquine and a type of, cholesterol. These substances are called membrane, stabilizers., l, Lysosomes are of two types – primary and secondary., l, Primary lysosomes are small (58 nm in diameter),, with electrondense contents., , Primary lysosomes are the storage form, of lysosomes and their enzymes are mostly inactive., l, The primary lysosomes disperse through the, cytoplasm. They are found in most cells but are, most abundant in phagocytic cells, eg., macrophages, neutrophils., l, Secondary lysosomes are larger and less electron, dense., l, They are formed by the fusion of one or more, primary lysosomes with a phagosome., l, Their primary function is digesting products of, heterophagy and autophagy., l, Secondary lysosomes occur throughout the, cytoplasm in many cells, in numbers that reflect, the cell’s lysosomal and phagocytic activity., l, Residual bodies (or tertiary lysosomes) are, membrane limited inclusions of various sizes and, electron densities associated with the terminal, phases of lysosome function., l, They contain undigestible materials such as, pigments, crystals and certain lipids. Some cells, (eg, macrophages) expel residual bodies as waste,, but longlived cells (eg, nerve, muscle) tend to, accumulate them., l, Autodigestion occurs when lysosome digests parts, of the cells., l, Missing or inactive lysosomal enzymes causes, serious childhood diseases (like Tay sach’s disease, or Pompe’s disease)., l, Functions of lysosomes are – digestion of useful, unwanted and harmful materials; renewal of cells, and organelles; by releasing nucleases, it may cause, mutations and breakage of chromosomes which may, lead to blood cancer., Ribosomes, l, Ribosome are small dense cytoplasmic particles, which are found individually in the cytoplasm and, also line the membranes of the rough endoplasmic, reticulum., l, Ribosomes were discovered by Robinson and, Brown (1953) in plant cell and Palade (1955) in, animal cell., l, Palade also coined the term ribosome., l, The ribosomes are especially numerous in actively, synthesizing cells, such as liver cells, pancreatic, cells, endocrine cells, lymphocytes, yeast cells, and, meristematic cells., l, They are fewer in less active and starved cells. As, expected the cancer cells have numerous ribosomes., l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń, , l, l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , They are absent in mammalian RBC., Ribosome is an organelle composed of RNA and, ribosomal proteins., Ribosomes are the site of protein synthesis, (production or construction) in a cell hence called, protein factory., There are 2 basic types of ribosome –, mitochondrial (like prokaryotic, eg PPLO, bacteria,, blue green algae) ribosomes which are smaller (20, nm) than the cytoplasmic ribosomes of eukaryotes, (25 nm)., Mitochondrial ribosomes (70S overall) have a, 50S and a 30S subunit; cytoplasmic ribosomes, (80S overall) have 60S and a 40S subunit Or the, ribosomes are also of two types: 80S and 70S., 80S ribosomes or cytoplasmic ribosome are, synthesized inside the nucleolus., The two subunits of 80S ribosome are – 60S (large, subunit) and 40S (small subunit). 5S RNA is, synthesised separately while others are formed by, the nucleolus. 80S ribosomes do not become, functional inside the nucleolus. Their subunits, come out of the nucleus and become operational in, cytoplasm., Cytoplasmic ribosomes occur in 2 forms– free, (found in cytosol) or bounded (membrane bound,, found exterior of the ER constituting rough ER)., 70S ribosome have 50S and 30S subunits., Magnesium ions play an important role in, holding the two subunits together and also in, maintaining the structure of the two subunits., Svedberg unit (S) is a measure of rate of, sedimentation of a particle in a centrifuge, where, the sedimentation rate is associated with the size, of the particle., Polyribosomes or polysomes are groups of, ribosomes distributed along a single strand of, messenger RNA (mRNA) in an arrangement that, permits synthesis of multiple copies of a protein, from the same message., Polysomes occur free in the cytoplasm (free, polysomes) and are attached to membranes of the, rough endoplasmic reticulum., Ribosomes read (translate) the mRNA code and, thus play a critical role in assembling amino acids, into specific proteins., Functions of ribosomes are –, –, Furnish enzymes and factors needed for the, formation of polypeptides., , –, , 159, , Provide sites for the attachment of tRNAs and, mRNA which participate in protein synthesis., –, Newly formed polypeptide is protected from, degradation by cytoplasmic enzymes in a, tunnel of the large ribosomal subunit before, releasing it into RER lumen., –, Groove between the two subunits furnishes, the site for the synthesis of polypeptide., Microbodies, l, The microbodies were first seen by Rhodin in, 1954 in the electron micrographs of mouse kidney, tubule cells., l, The microbodies occur in nearly all eukaryotic cells., They usually lie near the endoplasmic reticulum,, sometimes near the mitochondria or plastids or both., l, The microbodies are minute, simple, roughly, spherical sacs bounded by a single unit membrane., l, They contain a densely granular matrix which has, a regular core or nucleoid of crystalline material., The latter represents a variety of enzymes. These, enzymes catalyse oxidation reactions not, involved in respiration., l, The microbodies bud off from the rough, endoplasmic reticulum after receiving the enzymes, synthesized on the latter., l, The microbodies are of three main types:, peroxisomes (animal and plant peroxisomes) and, glyoxysomes., l, The peroxisomes were so called because of their, potential peroxidase activity. Peroxisomes in, contrast to lysosome are produced only on the, smooth ER. The rare total genetic disease, Zellweger’s syndrome is the result of malformed, peroxisomes. All types share peroxisomes catalase, activity., l, Animal peroxisomes are abundant in the liver, and kidney cells of vertebrates. They are also, found in other organs, such as brain, small intestine,, testis, and adrenal cortex. They also occur in the, invertebrates and protozoans, such as Paramecium., l, The peroxisomes contain one or more peroxide, producing enzymes like urate oxidase, Damino, acid oxidase, ahydroxy acid oxidase and bhydroxy, acid oxidase. Molecular oxygen is required for, producing hydrogen peroxide (H2O2)., l, Peroxisomes also contain another enzyme, catalase,, for metabolising hydrogen peroxide., l, Peroxisomes help in detoxifying the alcohol in, the liver cells. In animal cells, peroxisomes take
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 160, , ŕďőĽę– ĐĽŐńŐĹť, , part in oxidation of a number of biochemicals, including extra amino acids, alcohol and toxins., For example, about 50% of the alcohol consumed, by a person is detoxified by peroxisomes inside, liver cells. The microbodies may also take part in, lipid metabolism., l, Plant peroxisomes are found in the leaf cells, capable of photosynthesis., l, They contain enzymes present in both animal, peroxisomes and glyoxysomes. In addition, they, have enzyme glycolic acid oxidase that oxidises, glycolic acid (glycolate), a product of, photosynthesis, to glyoxylic acid, a process called, photorespiration., l, Photorespiration is so called because light induces, the synthesis of glycolic acid in chloroplast. The, entire process involves intervention of two basic, organelles – chloroplast and peroxisomes., l, The plant peroxisomes have enzymes for all these, reactions also. Thus, they are the most complex, microbodies., l, Glyoxysomes are microbodies which contain, enzymes for boxidation of fatty acids and, glyoxylate pathway., l, These microbodies have been recorded only in plant, cells. They are quite common in germinating oil, seeds such as castor, watermelon, cucumber, peanut, and others., l, Like other microbodies, glyoxysomes have a single, covering membrane and an enzyme rich matrix with, a crystalloid core. boxidation of fatty acids, produces acetyl CoA. The latter is metabolised in, glyoxylate cycle to produce carbohydrates., Glyoxylate cycle converts two acetyl CoA units, into C4 acids for gluconeogenesis., Plastids, l, Plastids are organelles enclosed by a double, membrane found in all plants and some unicellular, organisms (Euglena) of uncertain affinity., l, Plastids are of different types varying in shapes,, size, colour and function., l, E. Haeckel (1865) gave the term plastid., l, Plastid are the largest cell organelle, and involved, in the formation and storage of soluble and, insoluble carbohydrates., l, Plastids are broadly classified into two groups –, leucoplast i.e colourless plastids incapable of, performing photosynthesis and chromoplast ie, coloured plastids which are photosynthetically active., , l, , l, , l, , l, l, , l, l, , l, l, l, , l, , l, , l, l, l, l, , l, , These organelles are bound by two membranes. As, these organelles contain their own genetic material,, and protein synthesizing machinery i.e DNA, RNA, and ribosomes, they are capable of multiplication, by a fission like process., Leucoplasts are colourless plastids. Oval, spherical, rod like or filamentous leucoplasts occur in large, number in cells of fruits, seeds, tubes and rhizomes., Leucoplasts act as storage orgenelles., Leucoplasts are classified into three types on the, basis of the material stored , –, Amyloplast (of potato) stores starch., –, Elaioplast stores droplets of oil or fats., –, Proteinoplast store protein grains, (aleuroplast), Chromoplasts are coloured plastids with yellow,, orange and red carotenoids and other pigments., Chromoplasts are responsible for colours in, flowers, ripening fruits, autumn leaves and some, root like carrot., Chromoplast arises from proplastid or chloroplast., Proplastids are found in embryonic tissue, composed, only of an inner membrane, outer membrane, a small, amount of stromal space with DNA., The term chloroplast was coined by A.J.W., Schimper in 1883., Besides leucoplast (aleuroplast), starch grains can, develop in chloroplast., Chloroplast are the photosynthetic organelles (able, to capture light energy using H2O and CO2) of green, plants and contain the pigment chlorophyll., Chloroplast is the organelle which acts as factory, for the synthesis of sugars in autotrophic, eukaryotes., Each chloroplast is covered with a double, membrane containing a proteinaceous matrix, (or ground substance) called stroma., Stroma contains a small circular doublehelical, DNA, ribosomes and several enzymes., Ribosomes of chloroplasts are 70S type, containing 23S and 16S RNA., Many sheetlike lamellae (called thylakoids) occur, in stroma., The term thylakoid was given by Menke (1961)., About 2050 thylakoids are placed one above the, other like a stack of coins to form a granum., Many membranous tubules called stroma lamellae, interconnect thylakoids of different grana.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 161, , ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń–, , Table : Plastids, their occurrence and functions., , Kind of plastids, , Occurrence, , Functions, , Pigment, , Higher plants and, green algae, , Photosynthesis, , Chlorophylla and, chlorophyllb, , 2. Pheoplasts, , Brown algae, diatoms, dinoflagellates, , Light absorption, , Fucoxanthin along, with chl a and chl c, , 3. Rhodoplasts, , Red algae (rhodophyceae), , Light absorption, , Chl a along with, phycoerythnin and, phycocyanin, , 4. Bluegreen, chromoplasts, , Bluegreen algae, , Photosynthesis, , phycocyanin,, phycoerythrin,, chlorophylla, and, carotenoids, , 5. Chromoplasts of, photosynthetic bacteria, , Purple and nonpurple, sulphur bacteria, , Absorption of infrared, portion of light, , Bacteriochlorophyll, , Tomato, redpepper, flower, parts, fungi, bacteria and, fruits, , ––, , Lycopene and, capsanthin, , Starch storage, , None, , Oil storage, , None, , Protein storage, , None, , Chromoplasts, A. Photosynthetically, active chromoplasts, 1. Chloroplast, , B. Chromoplasts devoid, of photosynthetic, activity, 6. Carotenoids, , Leucoplasts, 7. Amyloplasts, 8. Elaioplasts, , 9. Aleuroplasts, , l, l, l, l, l, , l, , Storage tubers, cotyled, ons and endosperm, Epidermal cells of, Orchidaceae and, Liliaceae, Epidermal cells of, Helleborus and seeds, of Ricinus and Brazil nut, , Quantasomes are photosynthetic units present on, the surface of grana., Each quantasome contains 230 chlorophyll, molecules., Chlorophyll molecule has a complex porphyrin, ring with a long phytol chain., The metal magnesium is located at the centre of, chlorophyll molecule., The blood pigment haem is almost identical to, chlorophyll but it contains iron instead of, magnesium., Chlorophyll has four pyrrole rings, so called a, tetrapyrrole., , Pigments of chlorophyll are – chl a, b, c, d, e, and, carotenoids., l, Anthocyanin does not occur in chloroplast., l, Absence of chlorophyll in plants is known as, albinism., Mitochondria, l, Mitochondria is the third largest organelle in plant, cell and second largest organelle in animal cells., l, Mitochondria are the site of chemical reactions, that transfer energy from organic compounds to, ATP., l, ATP is called the energy currency of the cell., l, ATP production is called cellular respiration., l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 162, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The mitochondria were first seen in 1880 by, Kolliker, who isolated them from insect muscle, cells. They were named mitochondria by Benda, in 1898., Mitochondria can be stained differentially with, Janus Green and are easily distinguishable under, light microscope though ultrastructure can be, studied only under electron microscope., The mitochondria are often concentrated in the, more active regions of cells, like – in the muscle, cells, in the sperm, in the gland cells, in the intestinal, epithelial cells near the absorptive surface, in, dividing cells, and in cilia bearing cells, because, these location of mitochondria quickly deliver ATP, for cell activities., Each mitochondrion is bounded by 2 unit, membranes., The outer mitochondrial membrane has a smooth, contour and forms a continuous but relatively, porous covering. It is freely permeable to various, small molecules., The inner mitochondrial membrane is less porous, and thus is semipermeable. It has many, infoldings or cristae that project into the, mitochondrion’s interior., The cristae greatly increases the surface area of, the inner membrane by providing more space for, the chemical reaction to occur., The intermembrane space is located between the, inner and outer membranes and is continuous with, the intracristal space which extends into the cristae., The wide space between the cristae is called the, inner chamber. It is filled with a dense fluid, termed the mitochondrial matrix., The matrix contains proteins and enzymes, lipids,, some ribosomes, RNA, one or two DNA, molecules and certain ions, fibres, crystals and, granules. The ribosomes are 70S in size like those, of the prokaryotic cells. They are called, mitoribosomes in contrast to the 80S, cytoribosomes that occur in the cytoplasm. The, DNA molecules are circular, short and without, proteins as in the prokaryotic cells. All the three, types of RNAs (rRNA, tRNA and mRNA) are, present in the mitochondrial matrix. The ions, include Ca++ and Mg++. These are necessary for the, functioning of mitochondrial enzymes., The numerous soluble enzymes, present in matrix,, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , involved in specialized mitochondrial functions, such as the Krebs cycle (tricarboxylic acid cycle),, boxidation of lipids and mitochondrial DNA, synthesis., The inner surface is covered by inner membrane, subunits, also called F1 subunits/mitochondrial, particles/oxysomes etc., These particles were first seen by fernandez, Moran in 1961., In recent works only the stalked particles of the, inner membrane are involved in various, oxidation reaction and are supposed to supply, electrons to the interior of the organ. Therefore, they are termed as electron transport particle or, functional unit of mitochondria. These particles, are spaced about 100 Å interval., An oxysome consists of 3 parts – a rounded head, piece, or F1 subunit, joined by a short stalk to a, base piece, or F 0 subunit, located in the inner, membrane. There may be 100,000 to 1,000,000, oxysomes in a single mitochondrion., The oxysome, also called F0F1 complex, represents, adenosine triphosphatase, or ATPase, or ATP, synthetase, enzyme and is thus concerned with, ATP formation., The rest of the inner mitochondrial membrane, contains the electron carrier molecules (coenzymes), of the electron transport chain (flavoprotein, FeS,, CoQ, cyt. b, cyt c1, cyt. c, cyt. a, cyt. a3), succinate, dehydrogenase and enzymes of fatty acid synthesis., Mitochondria provide energy for chemical and, mechanical work by storing energy, generated from, cellular metabolites, in the high energy bonds of, ATP., Mitochondria grow and reproduce by fission or, budding and can undergo rapid movement and, shape changes., Mitochondria are also called semiautonomous, organelle as they synthesize their own DNA and, some proteins., Cardiac muscle cells are notable for their abundant, mitochondria. Epithelial cells lining the kidney, tubules have abundant mitochondria interdigitated, between basal plasma membrane infoldings where, active transport of ions and water occurs., Mitochondria are also called the powerhouse of, the cells because their primary purpose is to, manufacture adenosine triphosphate (ATP), which, is used as a source of energy.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń, , Enzymes of Mitochondria, Outer membrane, s Monoamine oxidase, s Rotenoneinsensitive NADHcytochrome c, reductase, s Kynurenine hydroxylase, s Fatty acid CoA ligase, Space between outer and inner membranes, s Adenylate kinase, s Nucleoside diphosphokinase, Inner membrane, s Respiratory chain enzymes, s ATP synthetase, s Succinate dehydrogenase, s bhydroxybutyrate, dehydrogenase, s Carnitine fatty acid, Constitute, acyl transferase, respiratory, Matrix (contain enzymes of Krebs cycle), unit, s Malate and isocitrate, dehydrogenases, s Fumarase and aconitase, s Citrate synthetase, s aketo acid dehydrogenases, s boxidation enzymes, Cilia & Flagella, l, Cilia are short, more numerous hair like structures, made of bundle of microtubules to help cells move., l, Cilia occur in group ciliata of protista, flame, cells of worms, larval bodies of many, invertebrates, epithelium of respiratory tract,, renal tubules, oviducal funnel, etc., l, A flagellum is like a cilium, but it is longer and, there is usually only one or 2 flagella on a cell., l, There are three main varieties of flagellum – the, bacterial flagellum (a helical filament that rotates, like a screw), archaeal flagellum (similar but, nonhomologous to the bacterial flagellum), and the, eukaryotic flagellum (a whiplike structure that, lashes back and forth)., l, Flagella of bacteria do not show 9 + 2 arrangement., l, The principal protein of cilia and flagella is, tubulin., l, Both cilia and flagella have following parts – basal, body, rootlets, basal plate and shaft., l, Basal body or kinetosome is also called basal, granule or blepharoplast., , l, , l, , l, , l, , l, l, , l, l, , l, , l, , l, , 163, , The basal bodies of cilia are found embedded in, the refractile, gelatinous ectoplasm immediately, beneath the cell surface and are uniformly spaced, in straight parallel rows. The basal bodies are said, to be homologous to the centriole., Rootlets are striated fibrillar outgrowths which, develop from the outer lower part of the basal body, and are meant for providing support to the basal, body., The rootlets are made of bundles of, microfilaments. They are commonly present in, the ciliated epithelium of lower animals but are, absent in the ciliated epithelium of mammals and, in the ciliated protozoa., Basal plate is an area of high density which lies, above the basal body at the level of plasma, membrane. In the region of basal plate, one sub, fibre of each peripheral fibril disappears. The central, fibrils develop in this area., Shaft is the hairlike projecting part of flagellum, or cilium., The shaft is covered on the outside by a sheath, which is the extension of plasma membrane., Internally, it contains a semifluid matrix having an, axoneme (an essential motile element) of 9, peripheral doublet fibrils and 2 central singlet, fibrils. This arrangement is called 9 + 2 or 11, stranded in comparison to 9 + 0 arrangement of, the centriole or basal body., Each axoneme is organized by and anchored in a, basal body., The function of cilia and flagella includes, locomotion for one celled organism and to move, substances over cell surface in multicelled, organism., The movements of cilia and flagella are brought, about by sliding of doublets past each other rather, than by their contraction., The cilia may beat in metachronous or, synchronous (isochronous) rhythm. In, metachronous rhythm, the cilia of a row beat one, after the other, whereas in synchronous rhythm all, the cilia of a row beat simultaneously., Movements of cilia and flagella are of four types –, pendulus movement, undulant, movement,, unciform movement, and infundibuliform, movement.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 164, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Major protein structures of the axoneme of the cilia and flagella., Axoneme component, 1. Tubulin (8 nm), 2. Dynein (24 nm), 3. Nexin link (86 nm), 4. Radial spokes (29 nm), 5. Sheath projection (14 nm), , Functions, Principal component of microtubule., Project from microtubule doublets and interacts with adjacent doublets, to produce bending., Hold adjacent microtubule doublets together., Extend from each of the nine outer doublets inward to the central pair., Projects as a series of side arms from the central pair of microtubules;, together with radial spokes these regulates the form of ciliary beat., , Functions of cilia and flagella are –, –, They help in locomotion in flagellate and, ciliated organisms., –, They create current for obtaining food from, aquatic medium. It is also called food current., –, In some protists and animals, the organelles, take part in capturing food., –, The canal system of porifers operates with the, help of flagella present in their collar cells or, choanocytes., –, In coelenterates, they circulate food in the, gastrovascular cavity. In tunicates and, lancelets, the cilia help in movement of food, and its egestion., –, In land animals the cilia of the respiratory, tract help in eliminating dust particles in the, incoming air., –, Internal transport of several organs is, performed by cilia, e.g., passage of eggs in, oviduct, passage of excretory substances in, the kidneys, etc., –, Ciliated larvae take part in dispersal of the, species., Centriole (Centrosomes), l, Centrioles are submicroscopic, microtubular,, subcylindrical structures which usually occur in, the form of two granules oriented at right angles, to each other. These are also called diplosomes (=, pair of centrioles)., l, Two centrioles are always found inside a specialized, distinctly staining cytoplasm that lacks other cell, organelles and is called centrosphere or, cytocentrum., l, The complex formed of centriole and, centrosphere was termed centrosome., l, The term ‘centrosome’ was given by Theodar, Boveri 1888., , l, , l, , l, l, l, , l, , l, , l, l, l, , l, , l, , l, , A centriole is 150 nm in overall diameter and 350, 500 nm long, containing 9 microtubule triplets, in a pinwheel array. Fibrils are absent in the, centre. The arrangement is therefore called 9 + 0., Each microtubule in a triplet, shares a portion of, the wall of the neighbouring microtubule., Centrioles are the structural organizers of the, cell., Centriole duplication is a prerequisite for cell, division and during mitosis the centrioles organize, the microtubules of the mitotic spindle., The centriole and associated golgi complexes, constitute the cell cytocentre, which appears as a, clear zone near the nucleus., During the S phase of interphase, each centriole, duplicates by giving rise to a procentriole that, grows at right angles to the original. During mitosis,, the new centriole pairs migrate to opposite cell, poles to organize the spindle., Centriole and basal bodies have common, structure and power of duplication., Basal bodies are structurally similar to centrioles, with 9 microtubule triplets., Basal bodies occur in the cytoplasm, one at the, base of each cilium or flagellum, and serve as the, anchoring points and microtubule organizers for, these structures., Some spindle microtubules (continuous fibres), extend from centriole to centriole. Others, (chromosomal fibres) extend from one centriole, to the centromere of a chromosome., The centrioles occur in nearly all animal cells, and in motile plant cells such as zoospores of, algae, sperm cells of ferns and motile algae. They, are absent in amoebae, prokaryotic cells, higher, gymnosperms and all angiosperms., Functions of centriole are –
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń, , –, –, –, , Serves as basal bodies for cilia and flagella., Concerned with spindle formation during cell, division, therefore called microtubule, organising centre (MTOCs)., Though centriole does not contain DNA yet, they are capable of forming new centrioles, with the helps of massules or pericentriolar, satellites which function as nucleating centres., , oils, alkaloids (eg atropine, colchicine, nicotine etc),, resins, gums, tannins, latex, nectar, gum, resins in, plant cells, etc., , Cytoskeleton, l, l, , Cell inclusions, l, l, l, l, , l, , l, , l, , l, , l, , l, , The cell inclusions are nonliving materials present, in the cytoplasm., They are often called deutoplasmic substances., They may be organic or inorganic compounds,, or both., The common cells inclusions are– stored organic, food materials, secretions and excretions and, inorganic crystals (See table given below)., Reserve food materials are of four major types:, starch grains, glycogen granules, aleurone grains,, fat droplets., Starch grains are found in plant cells only,, particularly in storage organs such as seeds, fruits,, rhizomes, and tubers. They are spherical, oval,, elliptical or polyhedral bodies. Each starch grain, contains a shining body called hilum made of protein., Fat droplets are found in adipocytes (fatstoring, cells) of animals, the endosperm of castor and, coconut and cotyledons of groundnut and, mustard seeds., Glycogen granules are small, spherical or large, rosetteshaped particles occurring near SER in liver, and muscle cells. Glycogen granules are also found, in bluegreen algae, slime moulds, fungi and, bacteria., Aleurone grains contain stored proteins. They are, present in all cereal grains such as wheat, maize, and barley below seed coat., Excretory and secretory products are of several, types like mucus in several animal cells; essential, , 165, , l, , l, l, , l, , l, , l, l, , l, , l, , The cytoskeleton is a cellular scaffolding or skeleton, contained within the cytoplasm., Cytoskeleton consists of a network of long protein, tubes and strands in the cytoplasm to give cells, shape and helps move organelles., The cytoskeleton is a mesh of filamentous elements, called microtubules, microfilaments and, intermediate filaments and provide structural, stability for the maintainence of cell shape., It is important in cell movement and in the, rearrangement of cytoplasmic components., Microtubules are larger, hollow tubules of the, protein called tubulin that maintain cell shape,, serve a tracks for organelle movement & help, cells divide by forming spindle fibres that, separate chromosome pairs., Microtubules are thickest cytoskeleton components, with diameters of 24 nm. They are fine tubular, structures of variable length, with dense wall (5, nm thick) and a clear internal space (14 nm across)., The walls are composed of subunits called tubulin, heterodimers, each of which consists of one a, tubulin and one btubulin protein molecule., The tubulin heterodimers are arranged in thread, like polymers called protofilaments., Microtubules increase in length by adding new, heterodimers to one end, called the nucleation site., This polymerization can be controlled, experimentally by regulating calcium ion, concentration or by treating cells with antimitotic, alkaloids., Colchicine blocks the process by binding to the, nucleation site. Vinblastine disrupts microtubules, by binding to free tubulin., Microtubules have roles in the maintenance of cell, , Table : Types of inorganic crystals, (a) Cystolith, (b) Crystal sand, (c) Raphides, (d) Sphaeraphides, (e) Prismatic crystals, , It consists of calcium carbonate crystals deposited around a cellulose framework,, as in epidermal cells of Momordica, hypodermal leaf cells of Ficus benghalensis., It is a powdery mass of calcium oxalate as in Atropa., These are needlelike crystals of calcium oxalate in Lemna, Eichhornia., These are starshaped groups of calcium oxalate crystals in Colocasia,, Chenopodium and Begonia., Crystals of calcium oxalate occur in the dry scales of Allium cepa.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 166, , l, l, , l, , l, , l, l, l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , shape, axoplasmic transport in neurons, melanin, dispersion in pigment cells, chromosome, movements during mitosis, organization of the, Golgi complex, and the shuttling of vesicles within, the cell., Unlike microfilaments, microtubules are unable to, contract. Shortening occurs via depolymerization., Microtubules are found throughout the cytoplasm, of most cells and in highly groupings in centrioles,, cilia, flagella, basal bodies and the mitotic spindle, apparatus., Microfilaments are rope like structures made of, 2 twisted strands of the protein actin capable of, contracting to cause cellular movement (muscle, cells have many microfilaments)., Microfilaments, the thinnest cytoskeletal, components (57 nm wide) are usually composed, of one of several types of actin protein., Microfilaments are contractile, but to contract they, usually must interact with myosin., Microfilaments occur in eukaryotic plant and, animal cells., Microfilaments often associate to form hexagonal, bundles. They may also occur in parallel bundles or, loose network. Microfilaments generally lie at sol, gel interphase as well as below plasma membrane., Microfilaments are also connected with spindle, fibres, endoplasmic reticulum, chloroplast, etc., During mitosis of animal cells, they have been found, associated with cleavage furrows., Microfilaments form the contractile machinery, of the cell, like formation and retraction of, pseudopodia, plasma membrane undulations,, microvilli, endocytosis, cytoplasmic streaming and, movement of other cell organelles., The microfilaments serve a number of functions –, support, intracellular movement, streaming, movement, cleavage, locomotion, change in form,, contraction, movement of villi, movement of plasma, membrane, membrane undulations, and formation, of spindle., Intermediate filaments are intermediate in, thickness (1012 nm) between microtubules and, microfilaments. They are supportive elements in, the cytoplasm of the eukaryotic cells except the, plant cells., They occur in the cell junctions and in the form of, basket around nucleus of animal cells., , l, , l, , Examples of intermediate filaments are –, cytokeratins in epithelial cells, vimentin in, mesenchymally derived cells (eg, fibroblasts., chondrocytes), desmin in muscle cells, glial fibrillary, acidic protein in glial cells, neurofilaments, (intermediate filament bundles) in neurons., The IFs serve a variety of functions –, –, They form a part of cytoskeleton that supports, the fluid cytosol and maintains the shape of, the cell., –, They stabilize the epithelia by binding to the, spot desmosomes., –, They form major structural proteins of skin, and hair., –, They integrate the muscle cell components, into a functional unit., –, They provide strength to the axons., –, They keep nucleus and other organelles in, place., –, Cardiac muscle cells are interconnected by, spot desmosomes. Desmin filaments, interconnect these desmosomes, allowing the, stress and strain of the contractile force of, one muscle to be transmitted to the other., , NUCLEUS, l, , l, l, , l, , l, l, l, l, , The nucleus is often the most prominent structure, within an eukaryotic cells and it controls all, functional activities of the cell., The nucleus is the control centre of the cell for, cell metabolism and reproduction., The nucleus is a specialised double membrane, bound organelle which contains genetic, information (DNA) on special strands called, chromosomes., A nucleus in the nondividing or metabolic phase, is called interphase nucleus as it controls metabolic, activites of the cell., The nucleus is also known as karyon and its study, is known as karyology., The cell nucleus was discovered by an English, botanist Robert Brown in 1831., The nucleus is the primary carrier of hereditary, material in the cell., The nucleus contains a linear code (DNA) for the, synthesis of cell components and products, conferring upon the cell a range of adaptability to, changing environmental conditions and to extrinsic, signals such as hormones.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń–, l, , l, , l, l, , l, , l, , l, , l, l, l, l, , l, , l, , The nucleus serves many functions –, –, Cell maintenance and growth, –, Cell metabolism, –, Genetic information, –, Cell replication, –, Ribosome formation, –, Variation, –, Cell differentiation., The nucleus can be divided into five parts: nuclear, membrane, nucleoplasm, nuclear matrix,, chromatin and nucleolus (or nucleoli)., Nuclear envelope is double membrane that, separate nucleoplasm from cytoplasm., The nuclear contents are set apart from the cytoplasm, by a double membrane called the nuclear envelope, (karyotheca) and a narrow (4070 nm), intermembrane space called the perinuclear, cisternae, or perinuclear space., The outer membrane is connected with, endoplasmic reticulum and its outer surface may, contain ribosomes while inner surface is smooth., In most cells, the barr body is attached to the, inner surface of the nuclear envelope. In a, neutrophilic leucocyte, it may appear as a drumstick, shaped appendage of the lobulated nucleus., The nuclear envelope is perforated by many, nuclear pores, each of which has a diameter of, about 70 nm and is bounded by 8 globular subunits, called annular proteins which presents an, octagonal appearance in some preparations., The pores and annuli together are called pore, complex., Nucleus communicates with cytoplasm through, nuclear pores., Structure of nuclear envelope facilitates, nucleocytoplasmic exchange of materials., The pores provide a channel for the movement, of important molecules between the nucleus, a nd c ytoplas m including nucleic acids, synthesized in the nucleus and used in cytoplasm, (mRNA, rRNA, tRNA) and proteins synthesized, in the cytoplasm and used in the nucleus, (histones, polymerases)., The nuclear envelope is formed during telophase, by coming together and fusion of small vesicles, into which the nuclear envelope breaks up during, prophase., Nuclear envelope serves four functions–, –, It maintains the shape of the nucleus., , 167, , –, , l, , l, , l, , l, , It keeps the nuclear contents in place and, distinct from cytoplasm., –, It regulates the flow of materials into and out, of the nucleus., –, Its pores allow the exit of ribosomal subunits, and tRNAs and mRNAs., The nucleus contains a viscous fluid, the, nucleoplasm (nuclear sap or karyolymph) which, keeps nucleus turgid and has a different pH from, cytosol., The nucleoplasm contains raw materials, (nucleotides), enzymes (DNA and RNA, polymerases) and metal ions (Mn++, Mg++) for the, synthesis of DNA and RNAs. It also contains, histone and nonhistone proteins for combination, with DNA, and other proteins for combination with, DNA, and the formation of ribosomal subunits., The nucleoplasm has the following functions –, –, It is the seat of synthesis of DNA, RNAs and, ribosomal subunits., –, It supports the chromatin material and nucleoli., –, It provides turgidity to the nucleus., –, Some of the proteins present in nucleoplasm, are essential for spindle formation., The nuclear matrix is a network of fine, crisscrossing,, acid proteincontaining fibrils which are joined to, the nuclear envelope by their ends. It forms a sort, of nuclear skeleton. It remains intact after the, chromatin and DNA have been removed. Terminal, ends of chromatin fibres or telomeres are embedded, in nuclear or fibrous lamina., Ø, , Ø, , Ø, , Enzymes of the nucleus, Many enzymes associated with DNA and, RNA synthesis are present in the nucleus., These enzymes include nucleoside, phosphorylase and ribonuclease. The, synthesis of DNA takes place inside the, nucleus. Bulk of the RNA is synthesized in, the nucleus and nucleolus and later these, RNAs move into cytoplasm. Enzymes, involved in protein synthesis are also present, in the nucleus., Glycolytic enzymes like aldolase, enolase,, 3phosphoglyceraldehyde dehydrogenase are, present in the nucleus., Inorganic materials like salts of calcium,, magnesium, zinc, iron are present in the nucleus., These are very essential for enzyme activities.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 168, , l, , l, , l, l, , l, , l, l, , l, , l, , l, , l, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , The nuclear matrix has the following functions –, –, It maintains the shape of the nucleus., –, Chromatin fibres are anchored to nuclear, matrix., –, The machinery for various nuclear activities,, such as replication and transcription, is, associated with the matrix., Nuclear chromatin is intensely basophilic and, consists of DNA and associated basic histone and, acidic or neutral nonhistone proteins., Histones are structural protein and nonhistones, are functional proteins., Chromatin is the interphase chromosomal, material, a complex between eukaryotic DNA and, protein., The major proteins of chromatin are the histones,, small proteins containing high proportion of basic, amino acids (arginine and lysine) that facilitate, binding with negatively charged DNA molecule., Chromosomes, the most highly condensed form of, chromatin, are visible during mitosis,., The chromatin forms chromosomes during cell, division by condensing and tight coiling of, chromatin fibres., The whole chromatin is not functional, only a, portion of euchromatin which is associated with, acid proteins, takes part in transcription or, formation of RNA’s., After cell division, the chromosomes change back, into chromatin fibres. Most of the fibres become, uncoiled, extended and scattered. They form the, euchromatin (true chromatin) of the interphase, nucleus. It stains lightly. Some chromatin fibres, remain coiled and compacted in the interphase also., They constitute the heterochromatin (the other, chromatin). It stains deeply. It lies close to the, nuclear lamina., Nucleolus (or nucleoli) was discovered by Fontana, in 1781, described by Wagner in 1840 and the, term ‘nucleolus’ was coined by Bowman in 1840., Nucleolus is characterized by the absence of, limiting membrane, presence of chromatin and, granules and fibrils of RNA and protein., There is one nucleolus for each haploid set of, chromosomes., Nucleolus is largely composed of RNA and it, stains more darkly than the nucleus., Nucleolus consists of DNA + RNA + protein., The nucleolus disappears during prophase of, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , mitosis and reappears after mitosis is completed., Distinct nucleolar components can be seen with, the electron microscope., Nucleolus disorganises itself during late prophase, and reappears during telophase., Nucleoli are the synthesis sites for most ribosomal, RNA (rRNA). They are largest and most, numerous in embryonic cells, in cells actively, synthesizing proteins and in rapidly growing, malignant tumor cells., Nuclei display wide variation in –, –, Size both absolute and relative to the amount, of cytoplasm (nucleocytoplasmic ratio);, –, Number per cell, allowing classification of, cells as enucleate, mononucleate, binucleate, or multinucleate;, –, Chromatin pattern i.e., the amount and, distribution of heterochromatin; and, –, Location, e.g., basal, central, ecentric., Nucleoli were divided into 2 main groups–, plasmasomes (or true nuclei), which stain with, acidic dyes and disappear during mitosis, and, karyosomes (or false nuclei), which stains with, basic dyes and are of flakes of chromatin., Nucleolus has four components – amorphous, matrix, granular part, fibrillar portion and, chromatin., Amorphous matrix is the homogeneous ground, substance of the nucleolus. Matrix is formed of, protein., Granular part consists of granules of the size of, 150—200 Å which lie scattered in the amorphous, matrix. The granules are formed of protein and, RNA in the ratio of 2 : 1. They are believed to be, precursors of ribosomes., Fibrillar portion (nucleolonema) is formed of a, large number of small fibrils that are 50 – 80 Å, long. The fibrils are made up of both protein and, RNA and are believed to be precursors of granules., Chromatin portion is that part of chromatin which, is associated with nucleolus. Depending upon its, position nucleolar chromatin is of two types–, perinucleolar and intranucleolar., The perinucleolar chromatin lies around the, periphery of the nucleolus. It gives rise to in growths, or trabeculae which produce the intranucleolar, chromatin., Functions of nucleolus are –, –, Principal or active site for the development of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ŚŕśĘŚśŕďń– ▒ŕĹďňĽŮŐň– Őě– ►Ěńń, , l, l, , ribosomal RNAs. It produces 70–90% of, cellular RNA in many cells. The chromatin in, the nucleolus contains genes or ribosomal, DNA (rDNA) for coding ribosomal RNA., –, Centre for the formation of ribosomes., –, Stores nucleoproteins. The same is synthesized, in the cytoplasm (over the ribosomes) and, transferred to nucleolus., –, Essential for spindle formation during nuclear, division., The configuration of nucleolus is maintained by, calcium., The messenger RNA is formed inside the nucleus, but outside nucleolus., , l, l, , l, , l, , VACUOLE, l, , l, l, , l, , Vacuole may be defined as a nonliving reservoir,, bounded by a differentially or selectively permeable, membrane, the tonoplast., The structure of tonoplast is similar to that of single, unit membrane, i.e., tripartite structure., In a young cell, vacuoles are extremely small in, size or may be absent. As the cell enlarges, these, smaller vacuoles fuse and form a large central, vacuole at maturity. So in a mature cell the, protoplasm is present as thin layer, pushed towards, the wall of the cell. This thin layer of protoplasm, is called as primordial utricle., Vacuole is not an airfilled cavity, rather it is filled, with a highly concentrated solution called vacuolar, sap or cell sap., , l, , 169, , This cell sap is generally neutral but at maturity, it becomes acidic., Cell sap contains many dissolved solutes such as, organic acids, soluble carbohydrates, soluble, nitrogenous compounds as nitrates, enzymes,, tannins, chlorides, phosphates, amino acids,, alkaloids and anthocyanin pigments., Vacuoles and their contents are considered to be, distinct from the cytoplasm and are classified as, ergastic., In general, vacuole functions include, –, Removing unwanted structural debris, –, Isolating materials that might be harmful or a, threat to the cell, –, Containing waste products, –, Maintaining internal hydrostatic pressure or, turgor within the cell, –, Maintaining an acidic internal pH, –, Containing small molecules, –, Exporting unwanted substances from the cell., –, Enabling the cell to change shape., –, Proteins found in the tonoplast control the, flow of water into and out of the vacuole, through active transport, pumping potassium, (K+) ions into and out of the vacuolar interior., Vacuoles also play a major role in autophagy,, maintaining a balance between biogenesis, (production) and degradation (or turnover), of, many substances and cell structures. They also aid, in destruction of invading bacteria or of misfolded, proteins that have begun to buildup within the cell., , Vacuoles, , Depending upon contents vacuoles are of 4 types, , Sap vacuoles, l Bubble like sac, l Contain cell sap, l Store and concentrate, mineral salts, l Contain water soluble, vacuoles pigments, —anthocyanin and, anthoxanthine, l Present in plant cell, , Contractile vacuoles, Helps in osmoregulation, and present in freshwater, protozoans, , Food vacuole, l Occur in protozoan, protists, lower, animals etc., l Contain digestive, enzymes, , Flow chart : Types of vacuoles., , Air vacuole or Pseudovacuole, l Occur in prokaryotes, l Store gases, regulate buoyancy, of cell, provide mechanical, support etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 170, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 20, , Biomolecules, l, l, , l, l, l, , l, l, l, , l, , l, , All molecules or chemicals functional in living, organisms are known as biomolecules., Biomolecules show optical activity i.e. they rotate, the place of polarisation of independent light. Organic, molecules produced abiologically lack this, phenomenon because products of biological origin, prefer the odd number of carbon atom per molecule., The organic molecules are found both in aqueous, and nonaqueous phase., The collection of different types of chemicals, present in cell is called cellular pool., Cellular pool is mainly constituted by, –, Inorganic compounds like salt, minerals etc., –, Organic compounds like carbohydrates, lipids,, amino acid etc., Organic and inorganic compounds in a cell occur, in 9 : 1 ratio., The constituents of cellular pool is also divided as, micro– and macro–molecules., Micromolecules include water, minerals,, carbohydrates, amino acid, lipids, nucleotides, enzymes, vitamins and hormones., Small molecules of cellular pool are characterised, by low molecular weight, simple molecular, conformation and higher solubility., Polymerisation of a large number of small, molecules gives rise to macromolecules such as, proteins, nucleic acid and certain carbohydrates, (polysaccharides)., , l, l, l, , l, , l, l, , l, , l, , l, , WATER, l, l, l, , Water is the most abundant substance of living, beings., In adult human body 20 22 litres (50% of the, total) is present inside the cells as intracellular water., The remaining water occurs in the extracellular, fluids like blood, lymph and tissue fluid., , l, , l, , The water content of actively living cells varies, between 60 95%., In human beings maximum water content is found, in the embryo 90 95%., Water is a double hydride of oxygen, i.e., a molecule, of water is made of one atom of oxygen and two, atoms of hydrogen. The hydrogen atoms are, connected with oxygen atom by covalent bonds., Water has a maximum solvent power as compared, to other liquids. This is because of its ability to, develop hydrogen bonds in association with most, of the polar substances, both electrolytes and, nonelectrolytes., Water is habitat for a large number of organisms, called aquatic organisms., Water allows the light to pass through it because, of its transparent nature. This helps the chloroplasts, to receive light while lying inside the living cells, deep inside the leaves., Presence of low hydration is essential for, dormancy of seeds. Availability of water helps a, seed to germinate through imbibition, swelling,, bursting of seed coat, activation and growth of, embryo., Many movements (e.g., opening and closing of, stomata, seismonasty in Mimosa, locomotion in, starfish) occur due to loss or gain of water (i.e., turgidity)., A small amount of water is in the ionic state., H 2 O ƒ H + + OH – .Water can, therefore, act both, as an acid and a base., Water is reagent is many chemical reactions., Because of its solvent action, water is an ideal, medium for chemical reactions., Water remains fluid due to rapid formation and, dissociation of hydrogen bonds amongst its, molecules.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 171, , ▲ĽŐŇŐńĚĘśńĚř–, l, , l, l, , l, , l, l, , Lipid bilayer which is basic component of cell, membrane is formed from phospholipids only in, contact with water., Water molecules form shells around dissolved, particles with the help of their H or O regions., Water has a high specific heat as well as hight, hermal conductivity. It, therfore, acts as a, temperature buffer as well as distribute heat, uniformly., Water has high latent heat of vaporisation., Evaporation of sweat causes elimination of excess, heat from the body., A number of waste products are eliminated in, solution form as urine., High cohesion force accounts for high tensile, strength of water while high adhesive force allows, it to be held inside transport channels., , l, , l, , l, , MINERALS, l, l, , l, l, l, , l, , l, , l, , l, , l, l, , Minerals occur in living organisms as components, of organic and inorganic molecules and ions., Minerals are formed as part of the cellular structure,, biologically active substances, enzymes activators, and several other functions., An organism may have upto 40 elements., They are divisible into two categories essential and, nonessential., An essential element is the one which takes part, in nutrition, growth, development and functioning, of the organisms., The organisms are unable to complete vegetative, or reproductive growth in the absence of the, essential element., A nonessential element is the one that is not, involved in metabolism, structure or functioning, of the organism., Deficiency of the element produces disorders which, can be rectified only by the supply of the element,, e.g., carbon, hydrogen, oxygen, nitrogen, calcium,, magnesium, manganese, etc., Depending upon their concentration required,, essential minerals are differentiated into two, categories – major and minor (in case of animals), or macronutrients and micronutrients (in case of, plants)., Major minerals are xalcium, phosphorus, sodium,, chlorine, magnesium and sulphur., Minor minerals are iron, copper, cobalt,, , manganese, molybdenum, zinc, fluorine, iodine and, selenium., Minerals required in extremely low concentration, are known as ultratrace minerals, e.g., silicon,, banadium, aluminium, boron, chromium, tin., Macronutrients are phosphorus, potassium,, calcium, magnesium, sulphur and iron. Framework, elements C, H and O are also macronutrients but, are not generally derived from minerals. Modern, day workers place iron in the category of, micronutrients on the basis of its concentration in, plants., Micronutrients are manganese, cobalt, zinc, boron,, copper, molybdenum and chlorine. Nickel, required, for enzyme urease, has recently been added to this, list., [For more on minerals refer Chapters “Mineral, and Nutrition in Plants” and “Nutrition and, Digestive System”], , CARBOHYDRATES, l, , l, , l, , l, l, , l, , l, l, , Carbohydrates are nature’s most abundant, organic substance and principal source of energy, for body., Carbohydrates contain carbon combined with, hydrogen and oxygen often in the same ratio as, in water (1C : 2 H : 1O)., Carbohydrates are usually divided into the, following three classes –, –, Monosaccharides or simplest sugars, –, Oligosaccharides (contain upto 10, monosaccharides unit), –, Polysaccharides (a polymer of more than 10, monosaccharide units)., Most sugars (monosaccharides) have the general, formula CH2O., Sugars containing three carbons are known as, trioses, those with four carbons as tetroses, those, with five carbons as pentoses and those with six, carbons as hexoses., Two trioses namely glyceraldehyde and, dihydroxyacetone are crucial intermediates in the, metabolism of glucose in glycolytic cycle., Erythrose is a tetrose which forms the raw, material for synthesis of anthocyanin and lignin., Pentose sugar, ribose is found in every animal and, plant cell. It occurs in a number of compounds, which play crucial roles in metabolism, e.g., ATP,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 172, , l, , l, l, l, l, l, l, , l, l, l, l, , l, l, l, , l, l, l, , l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , ADP, riboflavin and RNA. Its reduced form, deoxyribose is found in DNA., The hexoses are divided into aldoses or ketoses, according to whether they contain an aldehyde or, keto group., All hexoses are aldoses (glucose, galactose and, mannose), except fructose which is a ketose., The most important carbohydrate occurring in, animals is glucose and in plants is starch., Simple sugar of the blood is glucose. Blood sugar, level is a measure of glucose., Glucose is stored as glycogen in liver and muscles., Fructose (levulose) is the fruit sugar; it is the, sweetest among naturally occurring sugars., Sugars having a free aldehyde or ketone group can, reduce Cu2+ to Cu+. These are called reducing, sugars., Galactose occurs in milk as a component of the, milk sugar, lactose., Certain compounds of galactose, the galactosides,, occur in the brain and nervous tissue., Galactose is a constituent of agaragar and, galactolipids found in plant leaves., Mannose is an aldohexose, found in the, polysaccharides of plants. Mannose is also found, in blood serum, globulins and certain egg proteins., Mannitol is an alcohol of mannose commonly, found in brown algae., Oligosaccharides are formed by condensation of, 2–10 monosaccharides., Disaccharides are oligosaccharides with a, combination, of, two, molecules, of, monosaccharides., The common disaccharides are sucrose, maltose,, lactose and cellobiose., Sucrose is made up of glucose + fructose., Sucrose occurs in sugar cane and sugar beets,, which are the two most important sources of, commercial sugar., Sucrose has no free aldehyde or ketone groups;, sucrose is not a reducing sugar., Maltose or malt sugar is found during germination, of starchy seeds., Maltose is produced commercially from starch by, a starch hydrolyzing enzyme diastase., Lactose (glucose + galactose) is present in milk., Compared to the milk of cow, buffalo and goat,, lactose is highest in human milk., , l, l, l, l, l, l, l, l, l, l, l, l, l, , l, , l, , Human milk has a very high lactose content,, 7 grams per decilitre or about 200 mM and lactose, provides about 40% of the calories available to, the infant. The adaptive significance of this high, lactose content (the highest of any species, currently known) is probably twofold – (i) The, infant brain is large and requires glucose as a, metabolic substrate; lactose is broken down into, glucose and galactose prior to intestinal, absorption. (ii) From an osmotic standpoint, the, secretion of lactose obligates the concomitant, secretion of large amount of water. This water is, sufficient to meet the infant’s needs for sweating, and transpirational water loss, high in a warm, climate, as well as for urine formation. Because, lactose can be synthesized only from glucose,, maternal glucose utilization is increased by about, 30% in the fully lactating woman., Lactose does not occur in nature except as a product, of the mammary gland., Cellobiose consists of two molecules of bD, glucose; it cannot be split by mammalian enzymes., Raffinose is a trisaccharide (Galactose + Glucose, + Fructose)., Saccharine has a sweet taste,but it is not a sugar., Polysaccharides, are, polymers, of, monosaccharides., Glycogen and starch are both polymers of, aglucose., Starch in plants and glycogen in animals are two, food storage polysaccharides., Glycogen is known as ‘animal starch’., Glycogen is related to starch as both are, polysaccharides., A starving man first consumes reserve glycogen., Glycogen found in liver and muscles store energy, in mammals., Glycogen is broken down by the hormone glucagon, secreted by islets of Langerhans., Unlike starch, glycogen is watersoluble and gives, a red colour with iodine. Starch gives blue black, colour with iodine., Most plants store their chemical energy in the form, of starch. Starch grains are found in all parts of the, plants although in storage organs, eg. seeds, fruits,, rhizome etc, it is found in larger amount., Starch is of two types – temporary starch (formed, in the process of photosynthesis during day and is
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 173, , ▲ĽŐŇŐńĚĘśńĚř, , l, , l, , l, , l, l, l, l, l, l, , l, l, l, , l, l, , l, , converted to sugar during night) and permanent, starch (sugar above a certain level is converted to, permanent starch and found mostly in rhizome,, seeds and fruits)., Starch can be separated into two fractions amylose, and amylopectin. Natural starches are mixtures of, amylose (1020%) and amylopectin (8090%)., Amylose is an unbranched, helical molecule whose, sugars are joined by a(14) linkages., Amylose forms a colloidal dispersion in hot water, whereas amylopectin is completely insoluble., Amylose in starch is responsible for the formation, of a deep blue colour in the presence of iodine., Iodine is not very soluble in water, therefore the, iodine reagent is made by dissolving iodine in, water in the presence of potassium iodide. This, makes a linear triiodide ion complex which is, soluble. The triiodide ion slips into the coil of, the starch causing an intense blueblack colour., Amylopectin differs from glycogen in being much, less branched and having much smaller molecular, weight., The basic unit of starch is glucose., Cellulose and chitin are two structural, polysaccharides., Cellulose is an unbranched chain of glucose units, joined by b (1–4) linkages., Cellulose is a homoglycan hexosan., Cellulose is a constituent of cell wall of higher, plants, some algae and some fungi., Cellulose is digested by termites and sheep by, harbouring bacteria and protozoa that synthesize, the necessary enzyme, cellulase., Cellulose eaten by grazing animals is digested by, intestinal bacteria., Maximum amount of cellulose occurs in cotton., Chitin is a polysaccharide and is the principal, component of the exoskeleton of insects and, crustaceans; it is a polymer of Nacetyl, glucosamine. It is also present in cell wall of fungi., Inulin (Dahlia starch) is a carbohydrate, polymer, of fructose., Trioses, glyceraldehyde and dihydroxy acetone, are, important intermediates of both respiratory and, photosynthetic pathways., Pentose sugars, arabinose and xylose form polymers, (arabans and xylans) which are constituents of, hemicellulose., , l, , l, l, l, , l, , Ribose is an important sugar which is found in a, variety of chemicals like CoA, FAD, NAD, NADP, and ATP, RNA, DNA etc., Fats and aminoacids are formed from glucose and, other sugars., Heparin prevents blood clotting inside blood, vessels., Mucilage present as a protective coating around, aquatic plants, bacteria, bluegreen algae and some, animals is derived from polysaccharides., Pectins are commercial jellying agents., , LIPIDS, l, l, l, l, l, , l, , l, , Fats and their derivatives are together known as, lipids., They are heterogenous group containing mainly, carbon, hydrogen and oxygen., Term lipid was coined by Bloor (1943)., Lipids form about 35 percent of cell content., Lipids are biological molecules insoluble in water,, but readily soluble in nonpolar organic solvents, like chloroform and benzene., Lipids include seven major groups of substances:, fatty acids, triglycerides (neutral fats), waxes,, phospholipids, glycolipids, steroids and terpenoids., Broadly lipid can be classified into following types., Lipids, Simple lipids, (esters of fatty, acids with certain, alcohols), , Compound or, conjugate, lipids, , Derived lipids, e.g. hydrocarbons,, vitamins A, D,, E & K etc., , Phospho Glyco Sulpho Lipo, Waxes, Neutral or, lipids, lipids lipids proteins, (esters of, True fats, fatty acids, (fats & oils, with long, esters of, fatty acids chain aliphatic, Cere Ganglio Cyto, alcohols), and glycerol), brosides sides, lipids, Phosphatidic, acids, l, , l, l, l, , Lecithins Cephalins, , Plasma, logens, , Sphingo, myelins, , Fatty acids are organic molecules made up of long, hydrocarbon chain which contain a terminal, (–COOH) carboxyl group., Acetic acid CH3COOH is a simple fatty acid and, stearic acid CH3(CH2)16COOH is more complex., Most of the fatty acids found in nature have an, even number of carbon atoms (usually 14 to 24)., Fatty acids are either saturated (all carboncarbon
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 174, , l, l, , l, l, , l, , l, l, l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , bonds are single bonds) or unsaturated (with one, or more double bonds in the hydrocarbon chain)., The general formula of a saturated fatty acid is, CH3(CH2)nCOOH., If a fatty acid has only one double bond (palmitic, acid and oleic acid) it is said to be, monounsaturated fatty acid (MUFA)., The most common monounsaturated fatty acid, is oleic acid., If a fatty acid has more than one double bond (2, in linolenic acid, 3 in linoleic acid and 4 in, arachidonic acid), it is said to be polyunsaturated, fatty acid (PUFA)., Unsaturated fatty acids are slightly more abundant, in nature than saturated fatty acids, especially in, higher plants., Fatty acids become less and less water soluble as, the length of their hydrocarbon increases., Unsaturated fatty acids have lower melting point, than saturated fatty acids., Fats and oils are esters derived from glycerol (an, alcohol) and fatty acids., Depending upon the number of fatty acids, they are, called mono, di or triglycerides., Normally, three fatty acids can join to form a, glycerol molecule. So the glycerol serves as a binder, or carrier for fatty acids., Neutral animal fats formed from 16 carbon palmitic, acid and 18 carbon stearic acid are called as, tripalmitin and tristearin respectively. These are, pure fats., Palmitooleiostearin is a mixed fat as it bears, a molecule each of palmitic, oleic and stearic, acid., Table : Common biological fatty acids, , Common, Name, Saturated fatty acids, Capric acid, Lauric acid, Myristic acid, Palmitic acid, Stearic acid, Arachidic acid, , Unsaturated fatty acids, Palmitoleic acid, Oleic acid, Linoleic acid, Linolenic acid, Arachidonic acid, , Empirical Symbol, formula, , Number, of bonds, , C10H20O2, C12H24O2, C14H28O2, C16H32O2, C18H36O2, C20H40O2, , 10, 12, 14, 16, 18, 20, , :, :, :, :, :, :, , 0, 0, 0, 0, 0, 0, , 0, 0, 0, 0, 0, 0, , C16H30O2, C18H34O2, C18H32O2, C18H30O2, C20H32O2, , 16, 18, 18, 18, 20, , :, :, :, :, :, , 1, 1, 2, 3, 4, , 1, 1, 2, 3, 4, , l, , l, l, l, l, l, l, , l, , l, l, , l, , l, l, , l, l, , l, , l, , Essential fatty acids are some polyunsaturated fatty, acids which cannot be synthesized in the animal, body and must be supplied with food to avoid their, deficiency., Maximum number of double bonds present in, essential fatty acids is four., Rich source of polyunsaturated fatty acids in, the diet is vegetable oils., Sunflower oil is rich in linoleic acids and, minimum fatty acid content is in coconut oil., Mustard oil is one of the most unsaturated fatty, acid., Essential fatty acids serve as a precursor for, synthesis of prostaglandins., Waxes are complicated mixtures of long chain, alkanes with an odd number of carbon atoms, ranging from C 25 to C 35 and oxygenated, derivatives such as secondary alcohols and ketones., Waxes are chemically inert. They bear no double, bond in their hydrocarbon chain and insoluble in, water. Wax present in blood is cholesterol, palmitate., A common example is beeswax, a combination of, palmitic acid and myricyl alcohol (C30H61OH)., Wool fat or lanolin is secreted by cutaneous, glands and closely resembles sebum. It mainly, consists of palmitic, oleic or stearic acid and, cholesterol., Phospholipid is amphipathic molecule with both, hydrophilic (water soluble) and hydrophobic (water, insoluble) regions., The major phospholipids are esters of glycerol and, a mixture of fatty acids and phosphoric acid., Phospholipids are important cell membrane, constituents because they contain both polar and, nonpolar portion., Cephalin is found in the brain and acts as, insulation material for nerves., Glycolipids are primarily amp hipathic, carbohydrate glyceride derivatives and do not, contain phosphate. These include galactolipids, and sulfolipids (containing sulphur) found in, plastid membranes., Glycolipids are important constituents of certain, types of membranes, especially those found in plant, cells and cells of the nervous system., Steroids are derivatives of a fourmembered ring, compound called phenanthrene, e.g. cholesterol,, diosgenin, ergosterol.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇŐńĚĘśńĚř–, l, , l, , l, , l, l, , l, , l, , l, l, , l, l, l, l, l, , l, l, l, l, l, l, , Cholesterol is one of the most important animal, steroids. It is insoluble in water &, chemically unrelative., Cholesterol is useful since it is a structural, component of cells. Cholesterol forms bile salts, and hence essential for absorption of fatty acid. It, is synthesized from acetyl CoA or acetate (C2) in, the liver and thus not a dietary essential., Cholesterol is not found in plants, but the latter, contain other steroids collectively known as, phytosteroids., Cholesterol content is minimum in vegetable oils., Diosgenin, a steroid compound produced by the, yam plant (Dioscorea) is used in the manufacture, of antifertility pills., Ergosterol is the principal plant sterol present in, high concentration in yeast and upon irradiation is, converted to vitamin D., Bile acids are derivatives of cholesterol,, synthesized in liver; they are major components, of bile and aid in the emulsification of fat, (breakdown of larger fat molecules in smaller one), in small intestine., Lipids constructed from the fivecarbon compound, isoprene are called terpenes., Isoprene and its derivatives are joined in, various combinations to produce substances such, as vitamin A, coenzyme Q and carotenoids., Stigmasterol and sitosterols are phytosterols found, in soyabean oils and wheat gram oil respectively., Carotenoids are isoprenoid hydrocarbon of plant, origin containing 40 carbon atoms., Steroids act as chemical coordinators. Sterols are, required for growth and flowering in plants., Terpenes form a major component of essential oils., They impart characteristic flavour and odour to, essential oils like camphor, eucalyptus oil, limonene, and menthol., Vitamin A and chlorophyll bear terpenoid alcohol, called phytol., Lycopene pigment present in tomato (Lycopersicon, esculentum) is a terpenoid compound., Natural rubber is a polyterpene., Spermacetic, a wax obtained from whale is the, hardest wax., Cutin and suberin are lipids associated with plant, cell walls., Cutin is cross esterified and polymerised hydroxy, , l, l, l, l, , l, , l, , l, l, , l, , 175, , fatty acids and suberin is formed from phellonic, acid and glycerol., Suberin provides strength & impermeability to, cork cells., Cutin and cutile reduce epidermal transpiration., Fats serve as food reserve in both plants & animals., They function as concentrated food because as, compared to carbohydrates they yield more than, twice as much energy per unit weight (9.3 kcal/ :, 4.5 kcal/gm)., Fats can be converted to carbohydrates. Therefore,, fats stored in oil seeds (eg., groundnut, mustard,, castor, sunflower, cotton, coconut) not only provide, energy but also raw materials for growth of embryo., In seeds and spores lipids help in thermal insulation,, protection from ultra violet radiations and loss of, water., Vitamins A, D, E & K are soluble in fats., Edible oils extracted from many seeds are used in, cooking. Animals fats present in milk yield butter, and ghee., Drying oils having unsaturated fatty acids are used, in paint industry., , AMINO ACIDS AND PROTEINS, l, l, , l, , l, l, l, , l, , Amino acids are the building blocks of proteins., Each amino acid contain a centrally located carbon, atom called acarbon to which four groups are, attached : a basic amino group (–NH+3), an acidic, carboxyl group (–COO–), a hydrogen atom and a, group of varying chemical structures called a side, chain (R–) group), H, R(side chain group), Ca, +, –, COO, H3N, (Amino group), (Carboxyl group), Amino acid are organic acids having amino group, generally attached to a carbon or carbon next to, carboxylic group., Amino acid gives it a basic reaction while, carboxylic group provides an acidic property., With four different groups attached to it, the, acarbon is said to be asymmetric., Side chain R may be straight or branched, hydrocarbon chain or a cyclic group. The, hydrocarbon may be polar or nonpolar., The variously folded linear polymers of amino acids, are called polypeptides.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 176, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The amino acids are linked serially by peptide, bonds (–CONH–) formed between amino group, (–NH2) of one amino acid and carboxylic group, (–COOH) of the adjacent one., The sequence of amino acids present in a, polypeptide is specific for a particular protein. The, distinctive sequence of amino acid units is governed, by the codon sequence of the gene or cistron that, controls its formation., , Amino Acid, , Glycine, Alanine, Valine, Leucine, Isoleucine, , Abbreviation, three letter, , Gly, Ala, Val, Leu, Ile, , l, l, , l, l, , Only some 20 amino acids are used in the, synthesis of the all types of proteins., Amino acids not found in proteins are gamma, amino butyric acid (histone), serotonin (ornithine), and citrulline (balanine)., The great variety of proteins is due to the very large, possible sequence of amino acids., Essential amino acids are those which are taken, from food, not synthesized in the body., , Table : 20 different aminoacids, One, Polar/ Non polar/, Letter, Symbol, acidic / basic, Monoamino monocarboxylic acid, G, A, V, L, I, , Polar*, Non polar, Non polar, Non polar, Non polar, , Essential /, Non essential, , neutral, , Non essential, Non essential, Essential, Essential, Essential, , Monoamino dicarboxylic acid, Glutamic acid, Aspartic acid, , Glu, Asp, , Arginine, Lysine, , Arg, Lys, , E, D, , Acidic, Acidic, , Non essential, Non essential, , Diamino Monocarboxylic acid, R, Basic, K, Basic, , Essential, Essential, , Hydroxyl containing, Threonine, Serine, Tyrosine, , Thr, Ser, Tyr, , T, S, Y, , Polar*, alcoholic, Polar*, Polar*, aromatic, , Essential, Non essential, Non essential, , Polar*, sulphur, Non polar, Non polar, aromatic, , Non essential, Essential, Essential, , Non polar, aromatic, Non polar, heterocyclic, Basic, , Essential, Non Essential, Essential, , Sulphur containing, Cysteine, Methionine, Phenylalanine, , Cys, Met, Phe, , C, M, F, Heterocyclic, , Tryptophan, Proline, Histidine, , Trp, Pro, His, , W, P, H, , Amide containing, Glutamine, Aspargine, , Glu, Asp, , Q, N, , Polar*, Polar*, , acidic, , * These amino acid have an uneven charge distribution and are hydrophilic., , Non essential, Non essential
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇŐńĚĘśńĚř–, l, , l, , l, l, , l, , l, , l, l, , l, l, , l, l, , l, l, , l, l, l, l, , Other amino acids may be synthesized in the body,, particularly from carbohydrate metabolism. They, need not be supplied in the diet and are called as, non essential or dispensable amino acids., Glycine is the simplest amino acid, with lowest, molecular weight and no asymmetrical carbon, atom., When amino group is free it is said to be basic and, when carboxylic group is free it is said to be acidic., Lysine and arginine are examples of basic amino, acid as they contain two amino group and one, carboxylic group., Glutamic acid and aspartic acid bear one amino, group and two carboxylic group hence they are, acidic., Neutral amino acid contain equal number of amino, and carboxylic groups, e.g., glycine, valine,, phenylalanine etc., Alcoholic amino acids are serine and threonine., Aromatic amino acids are tyrosine, tryptophan and, phenylalanine. They possess cyclic structure with, a straight side chain bearing carboxylic and, amino group., Heterocyclic amino acids are tryptophan and, histidine. They have nitrogen in the ring structure., Non polar amino acid have no difference in, charge between one part of the molecule and, another, e.g., alanine, valine, leucine etc., Polar amino acid have both positive and negative, charge., Polar but uncharged amino acid have two charges, but they balance out each other so that amino acid, as a whole is uncharged, eg. glycine, threonine,, aspargine., Non polar amino acids are insoluble and polar, amino acids are soluble in water., Amino acids shows optical activity due to which, they can rotate the plane of polarised light. Amino, acid have two opposite electric charges in the region, of –NH2 and –COOH group. They can behave as, dipolar ion or Zwitter ion., Proteins derived from plants sources generally lack, in one or more amino acid., Rice, wheat and corn are all deficient in lysine., Corn also lacks tryptophan and rice lacks, threonine., Beans, peas and other legumes are the most complete, proteins in plants, but they lack methionine., , l, l, , l, , l, l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , 177, , The most complex amino acid having double, rings structure is tryptophan., The intestinal bacteria are able to synthesize both, esse ntial a mino acids and vitamins in, ruminants., Proteins which contain most of the essential amino, acids are termed first class, (eg animal proteins), while those do not, are called second class (eg, proteins of pulses)., The term protein was coined by Berzelius (1837), and Mulder (1838)., Protein is the principal organic constituents of, living cell in order of relative abundance., Proteins are large sized molecules or, macromolecules having one or more, polypeptides (chains of amino acids)., Proteins are the most abundant and most varied, on the macromolecules of the cells which constitute, about 50% of their dry weight., The minimum molecular weight of a protein is, that of adrenocorticotropin hormone (4500), insulin, (brovine insulin5733) and bacterial ferredoxin, (about 6000)., Other common proteins are human haemoglobin, (66500), enzyme urease (483000), isocitrate, dehydrogenase (1,000,000) and pyruvate, dehydrogenase complex (4,600,000)., Being macromolecules proteins are not freely, soluble in water but form colloidal complex with, the same., RNA takes part in the synthesis of protein at, ribosomes., Protein are made of carbon (51%), oxygen (25%),, nitrogen (16%), hydrogen (7%), sulphur (0.4%), and sometimes phosphorus is also present in, traces., On hydrolysis by protease enzyme, protein yield, amino acids. Proteins and amino acids are, amphoteric in nature (i.e., can react with both, acids and bases to form salts)., Proteins are oxidized by putrefaction process and, the products are amino nitrogen compounds, CO2, and H2O., Proteins are present as a colloidal solution in, protoplasm and in solid form as protein granules, in seeds., Proteins also occur as storage substances in, amorphous, crystallike or in solid form, e.g.,, aleurone grains (in cereals below seed coat).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 178, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The most abundant protein is rubisco (RuBP, carboxylase oxygenase enzyme system), which, constitutes 16% of total chloroplast protein., The smallest protein is adrenocorticotropic, hormone (ACTH) having 39 amino acids and mol., wt. 4500., The largest protein is pyruvate dehydrogenase, having 72 polypeptide chains and mol. wt., 46,00,000., A protein can have upto four levels of, organization – primary, secondary, tertiary and, quartenary., Primary structure is the description of basic structure, of a protein i.e., number of polypeptides, number and, sequence of amino acids in each polypeptide., The sequence of amino acids in each polypeptide, is determined genetically (by DNA) through, transcription and translation., The first protein to have its complete amino acids, sequence determined was insulin, a hormone that, , l, , l, l, l, l, , l, , l, , contain 51 amino acids., Secondary structure is the development of new, stearic relationships of amino acids present in the, linear sequence inside the polypeptides., There are three types of secondary structures a, helix, bpleated and collagen helix., Linus Pauling was awarded Nobel Prize in 1954, for study of a and bstructure of proteins., Secondary structures depends on hydrogen bonds, between C O and –NH groups., In a helix, a single amino acids chain is coiled, spirally by establishing hydrogen bonds between, first and fourth amino acids [e.g. keratin (hair),, myosin, epidermis (skin), fibrin (blood clot) etc.], In bpleated arrangement a sheet is produced by, holding of two or more polypeptide chains in, parallel or antiparallel manner., In collagen or tropocollagen helix, there are, generally three strands or polypeptides coiled, around one another., , Table : Functions of protein, Kind of Protein, , Example, , Function or Location, , 1. Structural, , Keratin, Collagen, Elastin, Sclerotic, Lipoprotein, , Found in skin, hair, nails, horns, feathers and wool, Component of connective tissue, bone, cartilage, tendons, Elastic connective tissue, Exoskeleton of insects, Structural component of cell membranes, organelles., , 2. Enzymes, , Pepsin, Amylase, Hexokinase, , Catalyse various biochemical pathways, , 3. Hormones, , Insulin and, Glucagon, ACTH, , Help to regulate the glucose metabolism, , 4. Carriers, , Pproteins, Haemoglobin, Myoglobin, Serum albumin, , Transport of organic molecules in plants, Transport of O2 in blood, Transport of O2 in muscles, Transport of fatty acids and lipids in blood, , 5. Protective, , Antibodies, Fibrinogen, Thrombin, , Form complexes with antigens, Form fibrin during blood clotting, Required in blood clotting, , 6. Contractile, , Actin, Myosin, , Protein filaments in muscles for contraction and locomotion, , 7. Storage, , Casein, Albumin, Glutelin, , Form milk protein, Egg white, Seeds of wheat, , Stimulates growth and activity of adrenal cortex.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 179, , ▲ĽŐŇŐńĚĘśńĚř–, l, , l, , l, l, l, , l, l, , l, , l, l, , l, l, , l, , l, , l, , l, , In tertiary structure, there is bending and, folding of various types to form spheres, rods or, fibres., Tertiary structure is stabilized by several types, of bonds hydrogen bonds, ionic bonds, vander, Wall’s interactions, covalent bonds, hydrophobic, bonds., Tertiary structure gives the protein a three, dimensional conformation., In protein structure, covalent bonds are the, strongest., Quarternary structure, is found only in, multimeric proteins. Each polypeptide develops, its own tertiary structure and functions as subunit, of the protein, e.g. haemoglobin., On the basis of their constitution, proteins are of, three types derived, simple and conjugate., Derived proteins are got from proteins through, denaturation, coagulation and breakdown, e.g.,, metaprotein, proteoses, fibrin etc., Simple proteins are made up of amino acids only., Additional nonamino groups are absent, e.g.,, histone, keratin, albumin etc., Conjugated proteins have nonamino prosthetic, groups., Depending upon the type of prosthetic group,, conjugate proteins are of several types i.e.,, nucleoproteins, chromoprotein, glycoproteins,, lipoproteins, metalloproteins, mucoproteins, and, phosphoproteins., Functional three dimensional form of a protein is, called native state., The state is maintained by specific bonds that form, its quaternary (4°), tertiary (3°), and secondary (2°), structure., On the basis of their structure protein are divided, into – fibrous (thread like proteins) and globular, proteins (rounded), eg. egg albumin, serum, globulins etc., The breaking of forces to bring about a change in, tertiary and secondary structure of protein is called, denaturation, primary structure remains intact., Denaturation is brought about by either heating, the protein or treating it with mineral acids when, the water soluble proteins undergo coagulation with, loss of biological activity., At a specific pH, a protein may be electrically, neutral because the number of positive charges are, , l, l, l, l, l, l, , exactly balanced by the number of negative charges., This pH is known as isoelectric point., Pprotein is a special type of protein present in, sieve tube elements., Human memory is believed to be stored in specific, protein called memory proteins., Best source of animal proteins are lean meat, (22%), fish (16.5%) egg, milk etc., Soyabean is the best source of plant protein, (43.2%)., Animal protein are rich in lysine. Plants proteins, are rich in methionine., Collagen is the most abundant animal protein., , NUCLEIC ACIDS, l, l, l, , l, l, , l, , Nucleic acids are the polymer of nucleotides which, are major components of all cells., Nucleic acids are found in both nucleus and, cytoplasm., The term ‘nucleic acid’ was introduced by Altmann, in 1889. Nucleic acid (DNA) was first isolated in, 1868 by Swiss physician Friedrich Miescher from, the nuclei of pus cells and called it nuclein., The link between generations is provided by nucleic, acids., Nucleotide is a compound of nitrogenous base,, a pentose sugar and phosphate, all linked together, by covalent bonds., Nucleotides also take part in energy transfer, system of cells and form about 2% of the cell, contents., The combination of a pentose sugar with a base, form nucleosides. The combination of nucleoside, and phosphate group form nucleotides. A number, of nucleotides combine to form nucleic acid., Base + Sugar ® Nucleoside + H3PO4 ® Nucleotide, , l, l, l, l, l, l, , Nitrogen base and pentose sugar form nucleoside., Nitrogen bases are of two types purines and, pyrimidines., Purines are 9 membered double ring nitrogen, bases which possess nitrogen at 1,3,7,9 position., Adenine (A) and guanine (G) are purine bases., Pyrimidines are 6 membered single ring nitrogen, bases that contain nitrogen at 1 and 3 position., The three dimensional structure of various, pyrimidines and purines has been deduced by X, ray diffraction analysis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 180, , l, l, l, l, l, , l, , l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Cytosine (C), thymine (T) and uracil (U) are, pyrimidine bases., 5 methyl cytosine occurs in wheat gram and thymus, gland., 5 hydroxy methyl cytosine occurs in, bacteriophage., 4 thiouracil, dihydroxyuracil and pseudouracil etc, are modified nitrogen bases present in tRNA., Uracil form nucleoside with only ribose sugar, while thymine forms the same with only, deoxyribose sugar., Both sugars (ribose and deoxyribose) are in, furanose or pentagon state with four carbon and, one oxygen atom., Free purine and pyrimidine bases are easily, separated by chromatographic or electrophoretic, methods., Other nitrogen bases (A,C,G) form nucleosides with, both sugars viz. adenosine, deoxyadenosine,, guanosine, cytidine, uridine, deoxyguanosine,, deoxycytidine, deoxyuridine., In nucleotides phosphate combine with sugar at its, 5 carbon, sugar with nitrogen base at 1¢ while, nitrogen base is usually attached to sugar at its 9, (purine) or 1 (pyrimidine) atom., Common nucleotides are – AMP, deAMP, (adenosine monophosphate, deoxyadenosine, monophosphate), GMP, deGMP, CMP, deCMP,, UMP, deUMP, TMP, deTMP., Nucleotides can have more than one phosphate,, e.g. two in ADP and three in ATP., ATP (adenosine triphosphate) has three high, energy phosphate bond while ADP (adenosine, diphosphate) has two high energy phosphate, bond., Abbreviations of ribonucleoside 5¢phosphates, Base, Mono, Di, Tri, Adenine, AMP, ADP, ATP, Guanine, GMP, GDP, GTP, Cytosine, CMP, CDP, CTP, Uracil, UMP, UDP, UTP, Abbreviations of deoxyribonucleoside 5¢phosphates, Base, Mono, Di, Tri, Adenine, dAMP, dADP, dATP, Guanine, dGMP, dGDP, dGTP, Cytosine, dCMP, dCDP, dCTP, Thymine, dTMP, dTDP, dTTP, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, l, , l, l, , For their polymerisation to nucleic acid state,, nucleotides are functional only in their, triphosphate state., UDP and ATP take part in polymerisation of, glucose while CDP and CTP take part in synthesis, of phospholipids., Nucleotides of nicotinamide and flavin are NADP+, (nicotinamide adenine dinucleotide phosphate),, NAD+, FAD, FMN., All the common ribonucleosides and deoxyribo, nucleosides occur in cells not only as the 5¢, monophosphates, but also as the 5¢diphosphates, and the 5¢triphosphates., The nucleotides serve four major functions, formation of nucleic acid (DNA, RNA),, formation of energy carriers (ATP and ADP),, formation of coenzymes (NAD, NADP) and, regulatory chemicals., There are two kinds of nucleic acids namely, deoxyribonucleic acid (DNA) and ribonucleic, acid (RNA)., DNA (deoxyribonucleic acid) is the genetic, material of most living organisms, which is a major, constituent of the chromosomes within the cell, nucleus and plays a central role in the, determination of hereditary characteristics by, controlling protein synthesis in cells. It is also, found in chloroplasts and mitochondria., DNA is a nucleic acid composed of two chains of, nucleotides in which the sugar is deoxyribose and, the bases are adenine, cytosine, and thymine. The, two chains are wound round each other and linked, together by hydrogen bonds between specific, complementary base to form a spiral laddershaped, molecule., RNA (ribonucleic acid) is a complex organic, compound in living cells that is concerned with, protein synthesis., In some viruses, RNA is also the hereditary material., Most RNA is synthesized in the nucleus and then, distributed to various parts of the cytoplasm., An RNA molecule consists of a long chain of, nucleotides in which the sugar is ribose and the, bases are adenine, cytosine, guanine, and uracil., Three types of RNA are – mRNA, rRNA and, tRNA., Messenger RNA (mRNA) is responsible for, carrying the genetic code transcribed from DNA to
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇŐńĚĘśńĚř, , l, , l, , l, , specialized sites within the cell (known as, ribosomes), where the information is translated into, protein composition., Ribosomal RNA (rRNA) is present in ribosomes., It is singlestranded but helical regions are formed, by base pairing within the strand., Transfer RNA (tRNA, soluble RNA, sRNA) is, involved in the assembly of amino acids in a protein, chain being synthesized at a ribosome. Each tRNA, is specific for an amino acid and bears a triplet of, base complementary with a triplet on mRNA., RNA can associate with proteins to form complexes, called ribonucleoproteins., [For more on DNA and RNA refer chapter Genetic, Material and Protein Synthesis]., , l, l, , l, , l, , ENZYMES, HORMONES AND VITAMINS, Enzymes, l, , l, l, l, , l, , l, , Enzymes are proteinaceous substances which are, capable of catalysing chemical reactions of, biological origin without themselves undergoing, any change., They are called as biocatalysts., Enzymes are mainly functional inside the living, cells., Enzymes functional outside the living cells are, called exoenzymes, eg., enzymes present in, digestive juices., Enzymes function inside living cells are known as, endoenzymes, e.g., enzymes of krebs cycle (inside, mitochondria)., Thousands of chemical reactions are taking place, in the body of a living organism, all of them are, mediated by enzymes., [For more on Enzymes refer chapter ‘Enzymes’], , Hormones, l, , Hormones are chemical substances which are, , 181, , produced in minute quantity by certain tissues or, organs called effectors and bring about, morphological or physiological changes in certain, tissues or organs called targets., Hormones are needed in very small quantity., Most of the body functions are regulated by, hormones, like growth, vegetative and sexual, development, thermal regulation, cellular oxidation,, metabolism of carbohydrates, proteins, fats etc., Number of plants hormones are five as auxin,, cytokinins, gibberellins, abscisic acid and, ethylene., Number of animal hormones are numerous, e.g.,, insulin, glucagon, calcitonin, glycocorticoids, sex, corticoids, adrenaline, thyroxine, growth, hormones, testosterone, progesterone, gastrin,, secretin etc., [For more on Hormones refer chapters “Endocrine, System and Phytohormones”], , Vitamins, l, , l, , l, , l, , Vitamins are essential but accessory food factors, which are required in minute quantities for normal, metabolism by forming coenzymes, helping in, intestinal absorption, working as antioxidants,, maintenance of body parts and utilisation of various, food components., Deficiency of vitamins produces disorders and, disease symptoms which can be corrected by, administration of that vitamin., Vitamins were discovered by Lumin (1881) while, first vitamin was isolated by Funk (1911). It was, B1 (thiamine)., Vitamins are synthesized by plants and bacteria., Animals and humans depends upon them for supply, of vitamins., [For more on Vitamins refer chapter ‘Nutrition and, Digestive System’]
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 182, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 21, , Enzymes, l, , l, l, , l, l, , l, l, l, , l, , l, l, l, , l, , Enzymes (the term coined by Kuhne, 1878) are, biocatalysts that increases the speed of a chemical, reaction without themselves undergoing any permanent, chemical change. They are neither used up in the, reaction nor do they appear as reaction products., Enzymology is the branch of science dealing with, enzymes., Edward Buchnar coined the name zymase for, the complex of biocatalysts extracted from yeast, and taking part in alcoholic fermentation., Buchnar is credited with the actual discovery of enzyme, and was awarded Nobel Prize for this in 1903., Sumner (1926) found enzymes to be, proteinaceous and crystallized the first enzyme, urease from Jack Bean (Canavalia ensiformis)., Duclaux proposed a system for naming the enzymes, by using the suffixase in 1883., Being by nature proteins means that enzymes are, fully biodegradable after use., Within biological cells many chemical reactions, occur but in the absence of enzyme they would, happen too slowly to sustain life., The basic enzymatic reaction can be represented, as follows., S+E®P+E, (where, E– represents the enzyme catalyzing the, reaction; S– the substrate, the substance being, changed; and P– the product of the reaction)., All enzymes are protein but not all proteins are, enzyme., No enzyme has been synthesized in vitro., Some enzymes are found inside cells (intracellular, enzymes), and some – especially digestive enzymes, are released so they have their effects outside the, cells (extracellular enzymes)., Enzyme can increase reaction rate by favouring, or enabling a different reaction pathway with, , l, , l, , l, l, , l, , l, , l, , l, , l, l, l, , a lower activation energy making it easier for, the reaction to occur., It is the magnitude of the activation energy, which determines just how fast the reaction will, proceed., Energy must be added to the reactants to overcome, the energy barrier, which is recovered when, products are formed., Energy required to overcome energy barrier is called, activation energy., The energy (called binding energy), obtained from, noncovalent interaction between enzyme &, substrate, is used to lower the activation energy, of enzyme controlled reactions., Simple enzyme is an enzyme which is wholly, made up of protein, no additional group is attached,, eg.: pepsin, trypsin, urease., Conjugate enzyme (also called holoenzyme) is, an enzyme, formed of two parts one protein, and other nonprotein., Many enzymes require the presence of other, compounds like cofactors before their catalytic, activity can be exerted. This entire active complex, is referred to as the holoenzyme; i.e., apoenzyme, (protein portion) plus the nonprotein part, cofactor, is called the holoenzyme., Cofactor is a general term for any nonprotein, (usually) component required at the active site, for enzyme activity., Cofactors include metal ion activator, coenzymes, and prosthetic groups., Coenzymes acts as carriers of acyl groups, hydrogen, atom, phosphate etc., A coenzyme is an small organic nonprotein, substance which is dialyzable, thermostable and, loosely attached to the protein part (means must, be dissociated from the enzyme in order to function).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ňŮťŇĚř–, l, , l, l, , A prosthetic group is an organic substance which, is dialyzable, thermostable and which is firmly, attached to the protein or apoenzyme portion, during the complete catalytic cycle., The part of the enzyme without the prosthetic, group is the apoenzyme., Coenzymes and prosthetic group are generally, derived from vitamins. When there is vitamin, deficiency, the coenzyme concentration decreases,, consequently enzyme function is depressed., Table : Watersoluble vitamins and coenzymes, Vitamin, , Coenzyme, , B1 Thiamine, , Thiamine pyrophosphate, (TPP), B2 Riboflavin, Flavin Adenine Dinucleotide, (FAD), Flavin MonoNucleotide, (FMN), B3 Nicotinic acid Nicotinamide Adenine, Dinucleotide (NAD), NADP, Pantothenic acid, Coenzyme A, Biotin, Biocytin, B6 Pyridoxine, Pyridoxal phosphate, B12 Cyanocobalamin Coenzyme B12, l, , l, , l, , l, , One of the properties of enzymes that makes them, so important as diagnostic and research tools is, the specificity they exhibit relative to the reactions, they catalyze., In general, there are four distinct types of, specificity:, –, Absolute specificity – the enzyme will, catalyze only one reaction., –, Group specificity – the enzyme will act only on, molecules that have specific functional groups,, such as amino, phosphate and methyl groups., –, Linkage specificity – the enzyme will act on, a particular type of chemical bond regardless, of the rest of the molecular structure., –, Stereochemical specificity – the enzyme will, act on a particular steric or optical isomer., The structure and specificity of an enzyme, depends on the linear sequence of amino acids, in polypeptide chain, while cofactor determines, the activity of enzyme., Though enzymes exhibit great degrees of specificity,, cofactors may serve many apoenzymes. For, example, nicotinamide adenine dinucleotide (NAD), , l, l, l, l, , l, l, l, l, , l, , l, , l, , l, l, , 183, , is a coenzyme for a great number of reactions in, which it acts as a hydrogen acceptor. Among them, are the alcohol dehydrogenase, malate, dehydrogenase and lactate dehydrogenase reactions., Enzyme exist in the cells as colloid., The whole surface of enzyme is not reactive., An enzyme contains an active site; a binding site, that binds the substrate during catalyzed reaction., Active site of an enzyme is formed of Rgroups, of selected amino acids during folding and, refolding of polypeptide chain., Part of the active site of enzyme where substrate, is held is known as buttressing group., Tertiary structure of enzyme is responsible for, active site production., More the number of active sites, more is the turn, over number and more is the activity of enzyme., The number of molecules of substrate converted, to product per enzyme molecule per second is, called the turnover number., Turnover number of enzyme is dependent on active, site, rapidity of reaction and separation of end, products., Turnover number of the fastest enzyme (carbonic, anhydrase, found in red blood cell) is 36 × 106 ., Carbonic anhydrase is an enzyme that catalyzes, the decomposition of carbonic acid into carbon, dioxide and water, facilitating the transfer of, carbon dioxide from tissues to blood and from, blood to alveolar air., carbonic, CO 2 + H 2 O ¾¾¾¾, ® H 2 CO3 ƒ HCO3- + H +, anhydrase, Enzyme activity is affected by enzyme, concentration, substrate concentration, product, concentration, temperature, pH, activators and, inhibitors., Temperature range for maximum functioning of, enzymes is 25° – 40°C., High temperature denatures (permanent) enzymes, and lower temperature inactivates enzymes., Above normal temperatures (say 60°C), heat alters, irreversibly the enzyme molecule. This, denaturation is due to molecular vibrations (caused, by heat) which change the shape of the protein,, altering the folding and internal crosslinkages, in its polypeptide chains. These changes , especially in the region of the active site mean, that the enzyme is inactivated, even when, returned to normal temperature.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 184, , l, l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , On heating only apoenzyme (protein) part gets, denatured and cofactor part remains unaffected., Below normal temperatures, enzymes become less, and less active, due to reductions in speed of, molecular movement, but this is reversible, so enzymes, work effectively when returned to normal temperature., The percentage of denaturation depends on degree, of hydration., Temperature is increased from 3°C to 40°C. The, rate of enzyme controlled biochemical reaction, will increase initially and then decrease., High fever is dangerous to human body because, it denatures enzymes. Hence urgent treatment, (giving antipyretics and applying cold cloth on, body or forehead) is required., Papain is used as meat tenderizer because it, continues its action even at high temperature of, cooking., The Q10 (temperature coefficient) for enzyme, activity is 23 within optimum range (i.e., rate of, reaction increases from 2 to 3 times for 10°C, increase)., The relationship of enzyme activity to pH is, represented by a bell shaped curve which has its, peak at the optimum pH., To determine the maximum speed of an enzymatic, reaction, the substrate concentration is increased, until a constant rate of product formation is, achieved. This is the maximum velocity (Vmax) of, the enzyme., In this state, all enzymes active sites are saturated, with substrate. This was proposed in 1913 by, Leonor Michaelis and Maud Menten. Since the, substrate concentration at Vmax cannot be measured, exactly, enzymes are characterized by the substrate, concentration at which the rate of reaction is, half its maximum., æ, Vmax [ S ] ö, Michaelis Menten equation çVo = K S ÷, m [ ] ø, è, describes how reaction velocity varies with substrate, concentration., Substrate concentration at which an enzyme attains, half its maximum velocity is called Michaelis, Menten constant (Km)., Km value of enzyme is substrate concentration, at 1/2 Vmax., Km does not depend on the concentration of, enzyme, but can vary with pH., , l, l, , l, , l, , l, , l, l, , l, , l, , l, l, l, , The lower the Km, the higher is the substrate, affinity of enzymes., Lineweaver Burke plot can be used to calculate, Km & Vmax as well as to determine the mechanism, of action of enzyme inhibitors., Conformational changes during formation of, enzyme–substrate complex have been observed, through Xray diffraction and optical rotation, analysis., Mechanism of enzyme action are explained on, the basis of lock and key model and induced fit, model., Induced fit theory of enzyme action was given, by Koshland (1959) and Lock and Key model, by Emil Fischer (1894)., Lock and key hypothesis explain specificity., Template/lock and key theory of enzyme action is, supported by the fact that compounds similar to, substrate inhibit enzyme activity., According to induced fit theory, the active site of, the enzyme is flexible, the substrates induces a, conformational change in the enzyme which is, alignment of amino acids or other groups at the, active site for correct orientation for substrate, binding., Transition state is an intermediate state which, occurs in induced fit model. During this, the old, chemical bonds breaks, atoms assume new position, and new bonds are formed., The transition state is highly unstable and persists, for a very short period.’, Many enzymes are secreted in inactive form to, protect cell proteins., An RNA enzyme or ribozyme is made of RNA, instead of protein generally ribozymes only catalyze, RNA splicing., Already, a synthetic ribozyme that destroys the, mRNA encoding a receptor of Vascular, Endothelial Growth Factor (VEGF) is being, readied for clinical trials. VEGF is a major, stimulant of angiogenesis, and blocking its action, may help starve cancers of their blood supply., , l, , l, , The ability of ribozymes to recognize and cut, specific RNA molecules makes them exciting, candidates for human therapy., Virus carry out no metabolism on their own, and must replicate using the host cell’s metabolic
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ňŮťŇĚř, , l, , l, , l, , l, , l, , l, , l, , l, l, l, l, , l, , machinery because they lack their own cellular, machinery and enzyme., Any substance that can reduce the rate of a reaction, is called an inhibitor. This inhibitor can either, have irreversible action or reversible action., Irreversible inhibition is one in which inhibitor, acts by forming covalent bonds with specific, groups of enzyme. It is of permanent nature, as, the enzyme conformation is harmed, dilution, of enzymeinhibitor complex does not regain, activity of enzyme because of denaturation of, enzyme., Reversible inhibition is one in which inhibitor, bind to enzymes through noncovalent bonds and, dilution of enzymeinhibitor complex results in, dissociation of the reversibly bound inhibitor and, recovery of enzyme activity., Reversible inhibitors can be divided into three, categories : noncompetitive inhibitors,, competitive inhibitors and uncompetitive, inhibitors., Noncompetitive inhibition occurs when the, inhibitory chemical, which does not have to, resemble the substrate, binds to the enzyme other, than at the active site., Noncompetitive inhibition occurs when the, inhibitor & substrate bind at different sites on, the enzyme., In noncompetitive inhibition Vmax of the reaction, decreases as this inhibition cannot be overcome, by increasing the concentration of substrate., Noncompetitive inhibition can result in change, in enzyme structure., Noncompetitive inhibition is reversible or, irreversible., Reversible non competitive inhibitors bind to, enzymes through noncovalent bonds., Reversible non competitive inhibition occurs when, the substrate has equal affinity for enzyme &, enzyme inhibitor complex., Some irreversible poisons destroy enzyme activity, by chemically modifying critical amino acid side, groups, and are generally unsuitable for therapeutic, purposes e.g., TPCK (tosyl phenylalauyl, chloromethyl ketone : 1 chloro 3 tosyl amido, 4 phenyl butanone), a irreversible inhibitor of, chymotrypsin, cyanides, DFP (diisopropyl, fluorophosphate, nerve gas) which reacts with, , l, , l, , l, l, l, l, , l, , l, l, , l, l, , l, , l, , l, , l, , 185, , hydroxyl group of serine of acetylcholinestrase,, penicillin etc., Cyanide kills an animal by inhibiting cytochrome, oxidase. This is an example of noncompetitive, inhibition., Enzyme inhibition caused by a substance, resembling substrate molecule through blocking, its active site is competitive inhibition., Competitive inhibition is reversible., Competitive inhibition supports the lock and key, hypothesis of enzyme action., Competitive inhibition is due to a substrate, analogue., The activity of succinate dehydrogenase is, inhibited by malonate and is the most common, example of competitive inhibition., Sulpha drugs are competitive inhibitors of folic, acid synthetase in bacteria (substitute for pamino, benzoic acid)., During competitive inhibition Vmax is same & K m, is increased., Km value is same in the presence or absence of, noncompetitive inhibitor, the noncompetitive, inhibitor do not interfere with the binding of the, substrate., In presence of a competitive inhibitor more, substrate is needed to achieve 1/2 Vmax., Irreversible inhibition occurs when the chemical, either permanently binds to or massively denatures, the enzyme so that the tertiary structure cannot, be restored. Nerve gas permanently blocks, pathways involved in nerve message transmission,, resulting in death. Penicillin, the first of the, “wonder drug” antibiotics, permanently blocks the, pathways certain bacteria use to assemble their, cell wall components., Alcohol and temperature above 45°C coagulate, enzymes by denaturing proteins. Due to this reason,, alcohol is used as disinfectant., Leninger et al (1933) considered prosthetic group, to be inorganic (metal ions) or organic (coenzyme), cofactor attached covalently to apoenzyme., Reactions mediated by enzymes and catalyst, are essentially reversible but forward and, backward reaction usually require different, optima., Lysozyme is an antibacterial enzyme, discovered, by Alexander Flemming (1922). Lysozyme is rich, in tear.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 186, , l, , l, l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , K i is the dissociation constant of enzyme –, inhibitor complex. It is applicable to competitive, inhibitor., Low Ki is essential for enzyme activity while, high K i decreases it., Decline in the activity of the enzyme hexokinase, by glucose6 phosphate is caused by allosteric, modulation (feed back inhibition)., Feedback inhibition is caused by blocking of, enzymes by accumulated end products., Allosteric or feedback is a type of noncompetitive, inhibition wherein the product of the reaction, sequence may act as a specific inhibitor of the, enzyme at or near the beginning of the sequence, with the result, the rate of entire sequence of, reactions is determined by the steady state, concentration of the end product., The end product is the inhibitor and the enzyme, inactivated is called allosteric enzyme., Allosteric enzymes are regulated by molecules, called effectors or modulators that bind non, covalently at site other than the active site., The enzyme remains unchanged at the end of, reaction and is free to interact again with more, substrate., E, , +, , S, , ES, , (Enzyme) (Substrate) (Enzyme, substrate, complex), , l, , l, , EP, , (Enzyme, product, complex), , E + P (products), , (Enzyme), , 1., 2., 3., 4., 5., 6., , l, , l, l, , Allosteric enzyme do not obey MichaelisMenten, or Km constant, instead it gives sigmoid kinetics., , l, , Based on type of reaction, IUBMB classified, , Table : Some other examples of, modulation., Allosteric, Allosteric, enzyme, activation, Hexokinase, ADP, (= glucokinase), Phosphofructokinase ADP, Diphosphofructose, ATP, phosphatase, Pyruvate, Acetyl CoA, carboxylase, Isocitrate, ADP, dehydrogenase, Glutamate, ADP, dehydrogenase, , allosteric, Allosteric, inhibitor, ATP, glucose, 6phosphate, ATP, AMP, ADP, ATP, ATP, NADH, , enzymes into – oxidoreductase (catalyze a redox, reaction), transferase (transfer a functional group),, hydrolase (cause hydrolysis reactions), lyase (break, CO, CC or CN bonds), isomerases (rearrange, functional groups), and ligase (join two molecules, i.e., CS, CN, CC)., The presence of elevated enzyme activity in the, plasma may indicate tissue damage accompanied, by increased release of intracellular enzyme., Allozymes are similar enzymes produced by, different genes., House keeping or constitutive enzymes are those, enzymes which are always present because of their, requirement., Enzymes, vitamins and hormones are common in, regulating metabolism., , Table : Classification of enzymes according to IUB (International union of biochemistry), S.N. Group, 1. Oxidoreductases—oxidases, dehydrogenases, reductases, 2. Transferases, 3., 4., 5., 6., , Function, , Take part in oxidation & reduction, reaction (transfer of electron), Transfer a group of molecule to, another, Break large molecule to smaller one, Hydrolases, Cleavage, removal of group without, Lysases, hydrolysis, addition of group to, double bond or reverse, Isomerases mutase epimerase Cause rearrangement of molecular, structure., Catalyse bonding of two chemical, Ligases, with the help of energy obtained from, ATP., , Example, Cyt. oxidases, succinate dehydro, genase, nitrate reductases., Glutamate pyruvate transaminase., Amylase, sucrase, lactase., DNA lysase, Histidine decarboxylase, aldolase., Phosphoenol pyruvate carboxylase, (Pepco).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 187, , ◄ňŮťŇĚř–, l, l, l, , l, , l, , l, , l, , l, l, l, , l, l, l, l, , l, , l, l, , l, , l, l, , In plants, enzymes occur in all living cells., Of the total enzymes present in a cell, mitochondria, account for 70% (maximum enzymes)., Enzymes having slightly different molecular, structure but performing identical activity on similar, substrate are isoenzymes. Example: lactate, dehydrogenase., Enzyme taking part in converting dihydroxyacetone, phosphate to glyceraldehyde phosphate belongs, to the type of isomerases., Enzyme catalyzing rearrangement of atomic, groupings without altering molecular weight or, number of atoms is isomerase., The enzymes are also an important tool in the, research studies, genetic engineering and other, DNA recombinant technologies., Restriction endonuclease is employed for cutting, double stranded DNA. Arber, Nathans and Smith, were awarded Nobel Prize (1978) for this discovery., Genetic engineering requires enzyme restriction, endonuclease., In a cell, digestive enzymes mostly occur in, lysosomes., Enzymes are also used for therapeutic means to, treat some disease like streptokinase is used in, cleaning blood clots inside blood vessels., Peroxidase is the smallest enzyme., Rubisco is most abundant enzyme., Diastases is the earliest known enzyme., Enzymes play an essential role in unzipping the, DNA double helix, and so enabling it to reproduce, and to send out the instructions for building proteins., The enzymes which are most important in, brewing are amylase enzymes (which convert, starches into sugars), and proteolytic enzymes, (which breaks down complex proteins into simpler, proteins and amino acids)., Antiageing enzyme is catalase (nonporphyrin, enzyme) that metabolises H2 O2 ., ELISA is an enzyme linked immunosorbent assay, when a protein antibody or antigen is detected by, means of a specific enzyme, eg. AIDS., Immobilisation of enzyme is attaching or trapping, enzymes in inert supporting materials for better, efficiency and recovering them after the reaction., A protein having both structural and enzymatic, traits is myosin., Antibodies that behave as enzymes are called, , l, , l, , abzymes., Flavoproteins involved in cellular oxidation are, called yellow enzymes., Biosensor is the ability of enzyme to recognize, specific molecules means they can be used as, molecular probes or biosensor. One of the, biosensors developed used the enzyme glucose, oxidase. Such a biosensor is invaluable to people, with diabetes who need to quickly monitor their, blood glucose level., Table : Enzymes as markers, 1., 2., 3., 4., 5., , Succinic dehydrogenase, and glutamate, dehydrogenase, DNA polymerase, Glucose6PO4, Acid phosphatase, LDH, , 6., 7., , RNA, Cytochrome oxidase, , Mitochondrial, marker, Nucleus, ER, Lysosomal marker, Cytoplasmic, fraction of cell, Ribosomes, Mitochondria, (inner membrane), , Table : Enzymes related hereditary disease, Enzyme, 1. Deficiency of tyrosine, 2. Defective galactose 1, Puridyl transferase, 3. Deficient phenylalanine, hydroxylase or mono, oxygenase, 4. Defective methaemoglobin, reductase, 5. Defective fructokinase, 6. Deficiency, of, hexosaminidase A by, which there is excessive, deposition of myelin on, nerves., 7. Defective phosphoribosyl, pyrophosphate, 8. Adenosine deaminase, , Disease, Albinism, Galactosemia, Phenylketonuria, , Methaemoglobinemia, Fructosuria, Tay Sachs, , Lesch, Nyhan, Syndrome, Immunodeficiency, diseases (SCID), 9. Phosphoribosyl pyro Gout, phosphate synthetase, 10. Calciferol hydroxylase Rickets
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 188, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 22, , Cellular Metabolism, l, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , Metabolism is the biochemical modification of, chemical compounds in living organisms and, cells., It is through the process of metabolism that, organisms process nutrients into the biochemical, tools and structures they need to maintain a living, state., Cell metabolism involves extremely complex, sequences of controlled chemical reactions called, metabolic pathways, usually a sequence of, enzymatic steps., Enzymes are crucial to metabolism because they, allow organisms to greatly accelerate slow, favourable reactions as well as couple unfavourable, reactions to available energy sources., By providing energy (usually in the form of ATP), to metabolic processes cells can successfully power, reactions that would otherwise never occur., Metabolism has two distinct divisions –, catabolism (destructive process) and anabolism, (constructive process)., Catabolism is a type of metabolic process occurring, in living cells by which complex molecules are, broken down to produce energy and reducing power., Catabolic reactions are primarily oxidation, reactions., The primary purpose of catabolism is to, regenerate ATP, the primary energy currency of, all cells. On balance, catabolic reactions are, normally exothermic., Anabolism is a constructive metabolic process, whereby energy is consumed to synthesize or, combine simpler substances, such as amino acids,, into more complex organic compounds, such as, enzymes and nucleic acids., Anabolic reactions are build up reactions which, are generally endergonic or energy absorbing., , CARBOHYDRATE METABOLISM, l, , l, l, , l, , The major function of carbohydrate in, metabolism is as a fuel to be oxidized and to, provide energy for other metabolic processes., The three principal monosaccharides absorbed from, the food are – glucose, fructose and galactose., Carbohydrate metabolism denotes the various, biochemical processes responsible for the, formation, breakdown and interconversion of, carbohydrates in living organisms., Carbohydrate metabolism includes –, –, Carbon fixation, whereby CO2 is reduced to, carbohydrate., –, Glycolysis, the breakdown of the glucose, molecule in order to obtain ATP., –, The pentose phosphate pathway, which acts, in the conversion of hexoses into pentoses, and in NADPH regeneration., –, Glycogenesis, the conversion of excess, glucose into glycogen in order to prevent, excessive osmotic pressure buildup inside the, cell., –, Glycogenolysis, the breakdown of glycogen, into glucose, in order to provide a steady level, of glucose supply for glucosedependent, tissues., –, Gluconeogenesis, de novo synthesis of, glucose molecules from simple organic, compounds. (i.e. formation of glucose or, glycogen from noncarbohydrates sources like, fats and proteins)., –, The oxidation of pyruvic acid to acetyl CoA,, a necessary step before the products of, glycolysis could enter into the citric acid cycle., –, Citric acid cycle, final common pathway, for the oxidation of carbohydrate, fat and, protein.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńńśńďŕ– ▐ĚŚďĐŐńĽřŇ, , Dicarboxylic acid shuttle, additional pathway, for regeneration of dicarboxylic acids., The reactions of carbohydrate metabolism cannot, take place without the presence of the B vitamins,, which function as coenzymes., Phosphorous, magnesium, iron, copper, manganese,, zinc and chromium are also necessary as cofactors., , –, l, , l, , Carbon fixation, l, , l, , Carbon fixation is a process found in autotrophs,, usually driven by photosynthesis, whereby carbon, dioxide is converted into organic compounds., In plants, there are three types of carbon fixation –, –, C3 plant that uses the Calvin Cycle for the, initial steps that incorporate CO2 into organic, matter, forming a 3carbon compound as the, 1st stable intermediate. Most broadleaf plants, and plants in the temperate zones are C3., –, C4 plant that prefaces the Calvin Cycle with, reactions that incorporate CO2 into 4carbon, compound. C4 plants have a distinctive leaf, anatomy. This pathway is found mostly in hot, regions with intense sunlight. Tropical grasses,, such as sugar cane and maize are C4 plants, but, there are many broadleaf plants that are C4., –, CAM plant that uses Crassulacean acid, metabolism as an adaptation for arid, conditions. CO2 entering the stomata during, the night is converted into organic acids, which, release CO2 for the Calvin Cycle during the, day, when the stomata is closed. The jade plant, (Crassula ovata) and cactus species are typical, of CAM plants., , Glycolysis, l, , l, , l, l, , l, l, , The sequence of reactions or pathway by which, glucose is degraded anaerobically to form, pyruvic acid is called glycolysis., Glycolysis occurs in all living organisms and in all, types of respiration. Hence James called it as core, respiration. This is also known as fundamental, respiration., Site of glycolysis is cytoplasm (cytoplasmic matrix, of a living cell)., The reduction of the glucose during glycolysis, produce compounds for the synthesis of protein,, fats and nucleic acid., Most of the steps of the glycolysis are reversible., Glycolysis may be divided into two phases – a, preparatory phase and an oxidative phase., , l, , l, l, l, l, , l, l, l, l, l, , 189, , In the preparatory phase breakdown of glucose, and low energy phosphorylation occurs, and, energy is used. In the oxidative phase high energy, phosphate bonds are formed and energy is stored., All reserve substances first undergo hydrolysis and, are finally converted into glucose., In majority of the organisms glucose acts as the, respiratory substrate., In glycolysis one molecule of glucose is converted, into two molecules of pyruvic acid., The sequence of reactions in glycolysis was traced, out by Embden Meyerhof Parnas (EMP). Hence, glycolysis is also called EMP pathway., No. of ATP used for phosphorylation of glucose in, glycolysis is 2 (1st and 3rd reactions)., No. of ATP formed during glycolysis is 4 (2 ATP, for each GAP)., Net gain of ATP during glycolysis is 2(4 – 2 = 2), If fructose6phosphate is oxidised through, glycolysis net gain of ATP is 3 (4 – 1 = 3)., No. of Pi utilised during glycolysis is 2., [For more detail refer chapter Respiration in, Plants], , Pentose phosphate pathway, l, , l, , l, l, , Pentose phosphate pathway is an alternate method, of aerobic respiration which occurs in the, cytoplasm of mature plant cells and accounting for, 60% of total respiration in liver cells and also occurs, in adipose tissue and lactating mammary glands., In this pathway, for every six molecules of glucose,, one molecule is completely oxidized into CO2 and, reduced coenzymes while five are regenerated., The pentose pathway is also known as, phosphogluconate pathway., Since, this pathway metabolizes glucose 6, phosphate by reactions that bypass the reactions of, glycolysis, it is also known as hexose, monophosphate shunt (HMP Shunt)., [For more detail refer Chapter Respiration in, Plants], , Glycogenesis, l, l, l, , Glycogenesis is the synthesis of glycogen (in, animals) and starch (in plants) from glucose., The chief sites of the formation of glycogen are, liver and muscle., Liver glycogen is mainly concerned with, maintenance of the blood glucose, but muscle, glycogen acts as a readily available source of hexose, units for glycolysis within the muscle itself.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 190, , ŕďőĽę– ĐĽŐńŐĹť, , The presence of glucose in blood is called blood, sugar. 100 ml of blood contains 80 – 100 mg of, glucose during fasting and 100 – 120 mg per 100 ml, of blood two hours after meal (post prandial)., l, l, , l, , Glycogenesis responds to both hormonal and, electrical control., Glycogenesis is stimulated by pancreatic, hormone insulin, growth hormone of pituitary, and cortisol of adrenal cortex., Glycogenesis takes place by a series of chemical, reaction. These are –, –, Glucose is phosphorylated to glucose6, phosphate by ATP in the presence of Mg2+ and, under the influence of an enzyme hexokinase, in the liver., –, Glucose6phosphate is then converted to, glucose1phosphate in an isomerization, reaction catalysed by the enzyme, phosphoglucomutase., –, Glucose1phosphate reacts with uridine, triphosphate (UTP) to form the active uridine, diphosphate glucose (UDPG) complex, and, inorganic phosphate (pyrophosphates, PPi) are, released. This reaction is catalyzed by the, enzyme UDPG pyrophosphorylase., –, The first carbon of the activated glucose of, UDPG form glycosidic bond with the carbon, ‘4’ of a terminal glucose residue of glycogen., This reaction is catalyzed by the enzyme, glycogen synthetase and uridine diphosphate, (UDP) is liberated. Hence a preexisting, glycogen chain becomes elongated as, successive14linkages occur., –, When the newly formed straight chain of, glycogen molecule has been lengthened to, between 6 and 11 glucose residues, a second, enzyme, branching enzyme, amylo1, 41,, transglucosidase acts on the glycogen. This, enzyme transfers a part of the14chain to a, nearly chain forming 1, 6, linkage, thus,, establishing a branch point in the molecule., –, Hence under the combined action of glycogen, synthetase and branching enzyme, the, molecule of glycogen is assembled., , l, , l, , l, l, , Gluconeogenesis, l, , Glycogenolysis, l, , Glycogenolysis is the conversion of glycogen to, glucose (which could occur several hours after a, meal or overnight) in the liver or, in the absence, , of glucose6phosphate in the muscle, to lactate., Or Glycogenolysis is the catabolism of glycogen, by removal of a glucose monomer and addition of, phosphate to produce glucose1phosphate. This, derivative of glucose is then converted to glucose, 6phosphate, an intermediate in glycolysis., Glycogenolysis transpires in the muscle and liver, tissue, where glycogen is stored, as a hormonal, response to epinephrine (e.g., adrenergic, stimulation) and/or glucagon, a pancreatic peptide, triggered by low blood glucose concentrations., Liver (hepatic) cells can consume the glucose6, phosphate in glycolysis, or remove the phosphate, group using the enzyme glucose6phosphatase and, release the free glucose into the bloodstream for, uptake by other cells., Muscle cells will not release glucose, but instead, use the glucose6phosphate in glycolysis., Glycogenolysis occurs in the following way:, –, The breakdown of glycogen is initiated by the, action of the enzyme phosphorylase. In the, presence of inorganic phosphate, the enzyme, catalyzes the removal of—1, 4 glycosyl, residues from the outermost chains of glycogen, molecule until about 4 glucose residues remain, on either side of 1, 6 branch., –, The hydrolytic splitting of 1, 6 linkages, requires the action of a specific debranching, enzyme (amylo—1, 6—glucosidase). The, combined action of phosphorylase and, debranching enzyme converts glycogen to, glucose 1phosphate., –, Glucose 1phosphate is then converted into, glucose 6phosphate by the action of enzyme, glucose 6phosphatase in the liver. This is the, final step in hepatic glycogenolysis and this is, manifested by a rise in level of blood glucose., –, When glycogenolysis occurs in muscles, the, reactions terminate at the glucose 6phosphate, stage because the liver phosphatase enzyme, is absent in muscle., , l, , Gluconeogenesis is the formation of glucose from, noncarbohydrate sources, such as certain amino, acids (primarily alanine and glutamine) and the, glycerol fraction of fats when carbohydrate intake, is limited., Liver is the main site for gluconeogenesis, except
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńńśńďŕ– ▐ĚŚďĐŐńĽřŇ, , l, , l, , l, , l, , l, , dehydrogenase. Malic acid then diffuses, across the mitochondrial membrane into the, cytosol where it is reoxidized to oxaloacetic, acid by an NAD+ linked cytoplasmic malic, dehydrogenase., Oxaloacetic acid + NADH + H +, Mitochondrial malic ¾, ¾¾¾¾¾¾¾¾¾¾, ® Malic acid + NAD+, dehydrogenase, Mitochondrial, malic, acid, Diffusion through, ¾¾¾¾¾¾¾¾¾¾¾¾, ® Malic acid, Mitochondrial membrane, in the cytoplasm, Malic acid + NAD+, , during starvation, period of fasting, or intense, exercise and when the kidney becomes important, in the process., The majority of the enzymes responsible for, gluconeogenesis are found in the cytoplasm; the, exceptions are is mitochondrial pyruvate, carboxylase and mitochondrial pyruvate, carboxykinase which is located in the mitochondria., The rate of gluconeogenesis is ultimately controlled, by the action of a key enzyme fructose1,6, bisphosphatase, which is also regulated through, signal transduction by cAMP and its phosphorylation., Gluconeogenesis cannot be considered to be a, reverse process of glycolysis, as the three, irreversible steps in glycolysis are bypassed in, gluconeogenesis. This is done to ensure that, glycolysis and gluconeogenesis do not operate at, the same time in the cell, making it a futile cycle., Therefore, it is reciprocal regulated between, glycolysis and gluconeogenesis. Many regulations,, which inhibit glycolysis, will activate, gluconeogenesis in reverse., The three irreversible steps in glycolysis are –, –, Phosphoenol pyruvic acid + ADP, Pyruvic Kinase, ¾¾¾¾¾¾¾¾, ® Pyruvic acid + ATP, –, Fructose, 6phosphate, +, ATP, Phosphofructokinase, ¾¾¾¾¾¾¾¾¾¾, ® Fructose 1, 6, bisphosphate + ADP, Hexokinase, ® Glucose 6, –, Glucose + ATP ¾¾¾¾¾¾, phosphate + ADP., In gluconeogenesis the three irreversible reactions, of glycolysis are bypassed by the following –, –, Phosphoenol pyruvate—formed from, pyruvate via oxaloacetate : First, pyruvic acid, is carboxylated to oxaloacetic acid at the, expense of an ATP. The enzyme pyruvic, carboxylase present in the mitochondria, contains a covalently attached prosthetic, group, biotin, which serves as a carrier of, activated CO2., Pyruvic acid + CO2 + ATP + H2O, , Cytoplasmic malic, ¾¾¾¾¾¾¾¾¾, ¾, ® Oxaloacetic acid, dehydrogenase, + NADH + H+, In the cytosol, oxaloacetic acid is, simultaneously decarboxylated and, phosphorylated by a second enzyme, phosphoenol pyruvic carboxylase, at the, expense of a second high energy phosphate, bond provided by GTP., Mg 2+, ˆˆˆˆˆ, †, Oxaloacetate, +, GTP, ‡ˆˆˆˆ, ˆ, Phosphoenol pyruvic acid + CO2 + GDP., , Acetyl CoA, ˆˆˆˆˆˆ, †, ‡ˆˆˆˆˆ, ˆ Oxaloacetate + ADP + Pi + 2H+, Mg2+, , Oxaloacetic acid, the product of pyruvic, carboxylase reaction does not diffuse readily, from the mitochondria. To achieve this end,, oxaloacetic acid is reduced to malic acid inside, the mitochondrion by an NADHlinked malic, , 191, , l, , The CO2 that was added to pyruvic acid by, pyruvic carboxylase comes off in this step., –, Fructose 6phosphate is formed from, Fructose 1, 6bisphosphate : The hydrolysis, of fructose 1, 6bisphosphate is catalyzed by a, specific enzyme fructose 1, 6bisphosphatase., This is a key enzyme for the conversion of, pyruvic acid and triosephosphate to glucose, during gluconeogenesis. It is present in liver,, kidney and striated muscle., –, Glucose is formed by hydrolysis of Glucose, 6phosphate : The conversion of glucose 6, phsophate to glucose is catalyzed by another, specific phosphatase, glucose 6phosphatase., It is present in intestine, liver and kidney,, where it allows these tissues to add glucose, to the blood. The enzyme is absent from the, muscle and adipose tissue., Six high energy phosphate bonds are used to, synthesize one molecule of glucose from 2 moles, of pyruvic acid in gluconeogenesis but only 2, ATP were generated in glycolysis in the conversion, of glucose to pyruvate.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 192, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , 2 pyruvic acid + 4ATP + 2GTP + 2NADH + 2H2O ®, Glucose + 4ADP + 2GDP + 6Pi + 2NAD+, During gluconeogenesis one mole of ATP is utilized, in the conversion of each pyruvic acid to, oxaloacetic acid in the mitochondria and another, one during the phosphorylation of 3, phosphoglyceric acid to 1, 3diphosphoglyceric acid, in the cytoplasm. In addition to 2 GTP, 4 moles of, ATP are required in the synthesis of one mole of, glucose from 2 moles of pyruvic acid., Gluconeogenesis occurring in the liver and kidney, maintains the glucose level in the blood so that, brain and muscle which have a high demand for, the glucose can extract sufficient amount of this, vital substance to meet their metabolic demands., , Oxidation of pyruvic acid, l, l, l, , l, , Pyruvic acid does not directly enter the Kreb cycle., It enters the Kreb cycle in the form of acetyl Co.A., The conversion of pyruvic acid into acetyl Co.A, takes place by pyruvic oxidase., Both decarboxylation and dehydrogenation occur, in this complex reaction and this together is called, oxidative decarboxylation., This is the first oxidative decarboxylation in, respiration., , l, l, , l, l, , One carbon of CH3COCOOH (pyruvic acid) is, liberated in the form of CO2., The essential cofactors for pyruvic oxidase are –, TPP (thiamine pyrophosphate), Mg++ ions, lipoic, acid (LA) Co.A. and NAD+., The residue of pyruvic acid is acetyl CoA., The connecting link between glycolysis and Krebs, cycle is Acetyl Co.A., [For more detail refer Chapter Respiration in Plants], , Citric acid cycle, l, , l, l, , l, l, , l, , Krebs cycle is the major pathway for the synthesis, of reduced coenzymes and controlled release of, energy during respiration., It is a common pathway of oxidative breakdown, of carbohydrates, fatty acids, and amino acids., Kreb cycle is the second step (basically the third, step after glycolysis and intermediate step) in plant, respiration., Krebs cycle occurs in the mitochondrial matrix., First organic acid formed during Krebs cycle is, citric acid. Hence Krebs cycle is also called citric, acid cycle., Tricarboxylic acids formed during Krebs cycle are, citric acid, cis–aconitic acid, isocitric acid and, oxalosuccinic acid. Hence Krebs cycle is also, , CARBOHYDRATE IN FOOD, Digestion and Absorption, LIVER, , via bloodstream, glucose, glycogen, , MUSCLE, glucose, , fatty acids, triglycerides, , via bloodstream, ADIPOSE TISSUE, [Used in triglyceride synthesis, (supply glycerol)], , glycogen, (storage), , pyruvate, lactate, , Via bloodstream, other tissues, (inc. liver), , Flow chart : Summary of carbohydrate metabolism, , TCA cycle
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńńśńďŕ– ▐ĚŚďĐŐńĽřŇ, , l, l, , l, , l, , known as tricarboxylic acid cycle (TCA cycle)., High energy compound directly formed during, Krebs cycle is GTP., One glucose molecule gives two molecules of, pyruvic acid. We get 6CO2, 8NADH, 2FADH2 and, 2ATP molecule in Krebs cycle., Krebs cycle is useful for the conversion of fats, into carbohydrates through Glyoxyllate cycle., Main enzymes useful in this cycle are isocitritase, and malic synthetase., The intermediate substances of Krebs cycle are, useful in intermediary metabolism and also act as, precursors and structural units of life., [For more detail refer chapter Respiration in Plants], , Dicarboxylic acid shuttle, l, , Dicarboxylic acid shuttle is a way of forming, phosphoenol pyruvate from pyruvic acid by, overcoming the pyruvic kinase block. In this, process, oxaloacetic acid is first generated by the, introduction of a CO2 molecule into a three carbon, molecule, pyruvic acid in the mitochondria., Oxaloacetic acid is then shuttled into the cytosol, and converted to phosphoenolpyruvate., , Disorders due to carbohydrate metabolism, Lactose intolerance (or hypolactasia), l, Lactose intolerance (or hypolactasia) is the, condition in which lactase enzyme needed for, proper metabolization of lactose (a sugar that is a, constituent of milk and other dairy products), is, not produced in adulthood., l, Lactose intolerance can sometimes be confused with, milk allergy, the former is a lack of the enzyme, lactase, while the latter is an aberrant immune, response (usually) to milk proteins., Hereditary fructose intolerance, l, Hereditary fructose intolerance (HFI) is a hereditary, condition caused by a deficiency of liver enzymes, that metabolise fructose., l, The deficient enzyme is fructose1phosphate, aldolaseB, this means that the fructose cannot be, further metabolised beyond fructose1phosphate., This traps phosphates; which are needed to, phosphorolyse glycogen phosphorolase to carry on, to make glucose. Therefore glucose cannot be made, through the breakdown of glycogen nor from, gluconeogenesis,, resulting, in, severe, hypoglycaemia., , l, , 193, , If fructose is ingested, vomiting, hypoglycaemia, and eventually kidney failure will follow., , Galactosemia, l, Galactosemia is a rare genetic metabolic disorder, which affects an individual’s ability to properly, digest the sugar galactose., l, Goppert first described the disease in 1917., l, Lactose in food (such as dairy products) is broken, down by the body into glucose and galactose.In, individuals with galactosemia, the needed enzymes, are severely diminished, leading to toxic levels of, galactose to build up in the blood, resulting in, hepatomegaly (an enlarged liver), renal failure,, cataracts, and brain damage., l, Type 1 galactosemia is caused due to GALT, deficiency., l, Galactose is converted into glucose by the enzyme, GALT (galactose1phosphate uridyl transferase)., This enzyme is the most common cause of, galactosemia., l, There are two variants of the GALT gene responsible, for galactosemia., l, One variant causes socalled classic galactosemia,, in which there is an extreme deficiency in galactose1, phosphate uridyltransferase. It is an autosomal, recessive condition. The gene for GALT was, mapped at 9p13. Most serious conditions are, prominent., l, The variant gene, responsible for Duarte, galactosemia, leads to about half the normal levels, of GALT. Individuals with Duarte galactosemia may, experience few or none of the serious symptoms of, classic galactosemia., l, The severity of the symptoms is dependent on a, number of factors, most importantly the amount, of lactose in the individual’s diet. It is also possible, to have one each of the classic and Duarte genes,, in which case GALT activity is intermediate., l, Types 2 and 3 galactosemia are caused by, deficiencies of galactokinase and UDP galactose, epimerase, respectively., Glycogen storage disease, l, Glycogen storage disease (synonyms: glycogenosis,, dextrinosis) is any one of several inborn errors of, metabolism that result from enzyme defects that, affect the processing of glycogen synthesis or, breakdown within muscles, liver, and other cell, types.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 194, , ŕďőĽę– ĐĽŐńŐĹť, , Diabetes mellitus, l, Diabetes mellitus is a metabolic disorder, characterized by hyperglycemia (high blood sugar), and other signs., l, The World Health Organization recognizes three, main forms of diabetes: type 1, type 2, and, gestational diabetes (occurring during pregnancy),, which have similar signs, symptoms, and, consequences, but different causes and population, distributions., l, Type 1 is usually due to autoimmune destruction, of the pancreatic beta cells which produce insulin., l, Type 2 is characterized by tissuewide insulin, resistance and varies widely; it sometimes, progresses to loss of beta cell function., l, Gestational diabetes is similar to type 2 diabetes,, in that it involves insulin resistance; the hormones, of pregnancy cause insulin resistance in those, women genetically predisposed to developing this, condition., , FAT (LIPID) METABOLISM, l, , l, , l, l, , l, , l, l, l, , l, l, , Fat catabolism, also known as lipid catabolism, is, the process of lipids or phospholipids being broken, down by lipases., The opposite of fat catabolism is fat anabolism,, involving the storage of energy, and the building, of membranes., Fats contain mostly carbon and hydrogen, some, oxygen, and sometimes other atoms., The three main forms of fat found in food are –, glyceride [principally triacylglycerol (triglyceride),, the form in which fat is stored for fuel], the, phospholipids, and the sterols (principally, cholesterol)., Fats provide 9 kilocalories per gram (kcal/g),, compared with 4 kcal/g for carbohydrate and, protein., The main pathways of lipid metabolism are, lipolysis, betaoxidation, ketosis, and lipogenesis., Lipolysis (fat breakdown) and betaoxidation, occurs in the mitochondria., Lipogenesis occurs in the cytosol. The main sites, of triglyceride synthesis are the liver, adipose, tissue, and intestinal mucosa., Fats (lipids) are stored in adipose tissue., These stored fat molecules are synthesized in the, body from the breakdown products of fat digestion, , l, , l, , l, , l, , (glycerol and fatty acids), in a process known as, lipogenesis., When needed as an energy source, the fat reserves, are mobilized, moved out of adipose tissue, and, broken down into glycerol and fatty acids in the, liver by the process of lipolysis., Fatty acids are changed in a series of reactions, called betaoxidation into acetyl CoA molecules,, which enter cell metabolism at the Kreb’s Cycle., When fats are being used as the primary energy, source such as in starvation, fasting or untreated, diabetes, an excess amount of acetyl CoA is, produced, and is converted into acetone and, ketone bodies., Ketosis occurs when the rate of formation of, ketones by the liver is greater than the ability of, tissues to oxidize them., , Oxidation of triacylglycerol, l, l, , l, l, , l, , Triacylglycerols are hydrolyzed to their constituent, fatty acids and glycerol in the adipose tissue., Free fatty acids (FFA) are released into the blood, plasma, where they are found combined with serum, albumin. This is followed by free fatty acid uptake, into tissues like liver, kidney, muscle, lung, testis, and adipose tissue itself., In these tissues, fatty acids undergo boxidation., Several hormones – epinephrine, norepinephrine,, glucagon, ACTH, growth hormone and thyrotropic, hormone – stimulate the release of fatty acids from, adipose tissue., Triglyceride synthesis and lipolysis do not follow, the same pathway in the adipose tissue., , b-oxidation of fatty acid, l, , l, , l, , The process of fatty acid oxidation is termed, boxidation since it occurs through the sequential, removal of 2carbon units by oxidation at the, bcarbon position of the fatty acylCoA molecule., These reactions occur in the mitochondria and, thus are closely associated with the electron, transport chain to produce energy in the form, of ATP., Each round of boxidation produces one mole of, NADH, one mole of FADH2 and one mole of, acetylCoA. The acetylCoA – the end product of, each round of boxidation – then enters the TCA, cycle, where it is further oxidized to CO2 with the, concomitant generation of three moles of NADH,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńńśńďŕ– ▐ĚŚďĐŐńĽřŇ, , l, , l, , l, , l, , l, l, l, l, , l, , l, , one mole of FADH2 and one mole of ATP. The, NADH and FADH2 generated during the fat, oxidation and acetylCoA oxidation in the TCA, cycle then can enter the respiratory pathway for the, production of ATP., The oxidation of fatty acids yields significantly, more energy per carbon atom than does the, oxidation of carbohydrates., Knoop (1905) proposed boxidation theory which, has since been confirmed by isotopic and other, techniques., According to this theory oxidation of fatty acid, occurs at the bcarbon, resulting in the formation, of a molecule of acetate from the terminal two, carbons and leaving a residue of a fatty acid, containing two carbons less than the original., The enzymes which activate fatty acids by, converting them to fatty acylCoA are called, ‘thiokinases’ or ‘acylCoA synthetases’., These enzymes are present in the outer, mitochondrial membrane., All the enzymes required for boxidation are, present in the mitochondria., Fatty acylCoA is formed in the cytoplasm. This, is impermeable to mitochondrial membrane., The acetate (acetylcoenzyme A) produced as a, result of boxidation can enter the citric acid cycle, and be oxidized in that cycle to carbon dioxide and, water and yield energy., Acetylcoenzyme A or active acetate can thus be, formed from carbohydrate, lipid as well as protein, and can be oxidized in citric acid cycle to provide, energy or it may be used for synthesis of fatty acids,, cholesterol or ketone bodies., aoxidation of fatty acids is found to occur in the, microsomal fraction of brain and other tissues and, plants., , Metabolism of glycerol, l, , l, , l, , Metabolism of glycerol takes place in the liver,, kidney, lactating mammary gland and intestinal, mucosa., The enzyme glycerokinase, catalyzes the activation,, by phosphorylation of glycerol to glycerol 3, phosphate or phosphoglyceraldehyde, (PGAL)., Glycerol + ATP + NAD+ ® Glycerol 3 phosphate, + ADP + NADH + H+.......... to oxygen : 3 ATP, This reaction requires 1 ATP for the phosphorylation, but yields 3 ATP in the transfer of H2 from NAD to, , l, , 195, , oxygen. PGAL, a normal intermediate in carbohydrate, decomposition, can then be respired via glycolysis (5, ATP) and the citric acid cycle (12 ATP); processes, that yield 17 ATP per molecule of PGAL., Complete aerobic respiration of one molecule of, glycerol, therefore, produces a total net gain of, 2 + 17 = 19 ATP moles., , Ketone bodies, l, , l, , l, l, , l, l, , l, , l, , l, , l, , l, , Ketone bodies are synthesized from acetyl CoA in, the liver mitochondria from where they diffuse into, the blood and are transported to peripheral tissues., Acetoacetic acid, bhydroxybutyric acid and acetone, are called the ketone bodies. They are readily, interconvertible., Ketone bodies are normally produced by liver and, utilized by extrahepatic tissues., These three acids are formed by the consequent, reactions when acetyl CoA formed in fatty acid, oxidation, enters the citric acid cycle. The entry of, acetyl CoA basically depends on the availability of, oxaloacetic acid for the formation of citric acid cycle., Ketone bodies production is regulated primarily, by availability of acetyl CoA., If mobilization of fatty acids from adipose tissue, is high hepatic boxidation will occur at a high, rate, & so will synthesis of ketone bodies from the, resulting acetyl CoA., Hydroxy butyrylCoA and acetoacetylCoA are, normally produced in the penultimate steps of b, oxidation., During starvation and in diabetes mellitus,, oxaloacetate is diverted to form glucose. On, account of its nonavailability in adequate, amounts, much of acetylCoA is converted to, acetoacetylCoA by con densation of two, molecules of acetylCoA., The blood levels of ketone bodies do not exceed, 1 mg/100 ml and less than 1 mg are excreted in, urine in 24 hours., Ketone bodies are utilized exclusively by, extrahepatic tissues, heart and skeletal muscle, use them particularly effectively., Both acetoacetic acid and bhydroxybutyric acid, are moderately strong acids and are buffered when, present in blood or the tissues. Their continual, excretion causes some loss of buffer cation Na+, which progressively depletes the alkali reserve,, causing ketoacidosis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 196, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The ketoacidosis is associated with nausea,, additional fluid loss and depression of the central, nervous system leading ultimately to profound coma., The concentration of total ketone bodies in the blood, of wellfed mammals does not normally exceed 1, mg/100 ml. Loss via the urine is usually less than, 1 mg/24 hrs in man. Higher than normal quantities, present in the blood or urine constitute ketonemia, or ketonuria respectively. The overall condition is, called ketosis., Causes of ketosis are –, –, The simplest form of ketosis occurs in, starvation. In the absence of food, glycogen, stores are rapidly depleted and survival, depends largely on energy derived from fat, deposits in the body., –, Clinically, the most important cause of, ketosis is diabetes mellitus. In the diabetic, individual, glucose is present in excessive, amounts in the fluids of the body but the, metabolic defect viz., insulin deficiency,, prevents glucose utilization from operating, at a normal rate. From the point of view of, the effect upon lipid metabolism, diabetes, and starvation resemble one another. Since, glucose is not being catabolized at a normal, rate in mus cle or in liver, exces sive, mobilization of depot fat leads to lipaemia, and fatty liver., , –, –, , Abrupt replacement of a normal diet by one, low in carbohydrate and very rich in fats often, leads to ketosis., Renal glycosuria and severe exercise in the, post absorptive state may also result in, ketosis., , Synthesis of fatty acid, l, , l, , l, , The biosynthesis of long fatty acids chain in animal, tissues, plants & microorganisms is not a direct, reversal of fatty acids oxidation, although acetyl, CoA is the starting material., Fatty acid synthesis occurs in the cytoplasm of, cells (compared to boxidation which occurs inside, the mitochondria)., The process of fatty acid synthesis involves two, regulatory steps:, –, The first step is the carboxylation of acetyl, CoA in the cytosol to form malonyl CoA., The acetyl CoA and malonyl CoA are, transferred to ACP (acyl carrier protein) by, the action of acetyl CoA transacylase and, malonyl CoA transacylase respectively., Catalyzed by the biotindependent acetyl, CoA in the cytosol CoA carboxylase (known, to be key enzyme of fatty acid synthesis), an, enzyme that transfers CO2 to substrates, this, step is the ratelimiting step and therefore a, very important site in the regulation of fat, accumulation. If sufficient biotin is not, , Table : Differences between fatty acid synthesis and beta oxidation., The two processes are superficially the reverse of one another. There are however several important, differences allowing for differential control, with one process inhibited while the other is stimulated., Fatty acid Synthesis, , Beta Oxidation, , Place, , Cytoplasm, , Mitochondrial matrix, , Bounding, of intermediates, , ACP (acyl carrier protein), , CoA (coenzyme A), , Enzymatic activities, , Combined in a Multienzyme, complex FAS (fatty acid synthetase), , The enzyme needed are, structurally not linked, , Reducing agents are NADPH, , Oxidation agents are NAD+ & FAD, , Synthesis occur by the, addition of two carbon units, (derived from acetyl CoA) but, the actual donor is malonyl CoA, , Results in the removal of, two carbon acetyl CoA units, , Regulated by acetyl CoA carboxylase, , Regulated by acetyl CoA availability
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 197, , ►Ěńńśńďŕ– ▐ĚŚďĐŐńĽřŇ, , l, , l, , l, , l, , l, , available for carboxylation of acetylCoA,, fatty acid synthesis will not occur., –, The second major point of regulation in, fatty acid synthesis is the decarboxylation, of the malonyl group, catalyzed by fatty acid, synthase. The multienzymatic activity of fatty, acid synthase (FAS) regulates fatty acid, synthesis in higher organisms like yeast, birds, and mammals. FAS is present in the cytosol, of many tissue like kidney, brain, lung,, mammary gland and adipose tissue. Synthesis, of fatty acids by the FAS complex stops after, sixteen carbons have been added (Palmitate), and further elongation and the addition of, double bonds are carried out by other systems., The rate of fatty acid synthesis is controlled by the, equilibrium between the monomeric and polymeric, acetyl CoA carboxylase., Hormones plays an important role in lipid, metabolism. Fatty acid synthesis is regulated by, phosphorylation dephosphorylation reactions., Insulin stimulates the dephosphorylation of acetyl, CoA carboxylase, activating fatty acid synthesis., Phosphorylation of acetyl CoA carboxylase by, the hormones epinephrine, norepinephrine and, glucagon result in the inactivation of this enzyme,, inhibiting synthesis of fatty acids from acetyl, CoA., The role of fatty acid synthesis is to –, –, Supply the body’s needs for particular fatty, acids not supplied in the diet., –, To convert excess dietary glucose to fatty acids, for storage., Glucose is the major source of acetyl CoA for, fatty acid synthesis., , Abnormalities in lipid metabolism, l, , l, , l, , Obesity: Excessive deposition of fat in the depots, with decreased mobilization causes obesity. Obesity, of nonendocrinal causes is always due to ingestion, of more food than necessary to meet the metabolic, needs of the adult., Gaucher’s disease: Cerebrosides are increased in, brain, liver and spleen. There is an imbalance, between the synthesis and the breakdown of this, lipid., NiemannPick’s disease: Sphingomyelins, accumulate in liver, spleen, bone marrow, lung, and lymph nodes, Gangliosides or brain show, , l, , l, , degeneration. Several variants of the disease, occur. The abnormality here also is an imbalance, betw een synthesis an d brea kd ow n of the, sphingomyelins., TaySachs Disease: Abnormal glycosides, accumulate in brain. There is retarded development,, paralysis, dementia and blindness. The child does, not usually survive beyond 2 to 4 years., Fabry’s Disease: An abnormal galactosyl, sphingolipid accumulates in many tissues. Death, occurs due to cardiac or renal failure., , PROTEIN METABOLISM, l, l, , l, , l, , l, l, , l, , l, l, l, l, , Proteins contain carbon, hydrogen, oxygen,, nitrogen, and sometimes other atoms., They form the cellular structural elements, are, biochemical catalysts, and important regulators, of gene expression., Nitrogen is essential for the formation of twenty, different amino acids, the building blocks of all, body cells., The amount of intake of nitrogen in food (mainly, as protein) will be balanced by excretion of an, equal amount of nitrogen in urine (in the form of, urea mainly; uric acid, creatinine, creatine and, amino acids contribute to a minor extent) and faeces, (mainly unabsorbed nitrogen). The animal is said, to be in nitrogen balance., Amino acids can also be converted into glucose, and used for energy, through gluconeogenesis., Amino acids are characterized by the presence of, a terminal carboxyl group and an amino group in, the alpha position, and they are connected by, peptide bonds., Protein catabolism is the breakdown of proteins, into amino acids and simple derivative, compounds, for transport into the cell through the, plasma membrane and ultimately for the, polymerisation into new proteins via the use of, ribonucleic acids (RNA) and ribosomes., The final products of protein catabolism include, carbon dioxide, water, ATP, urea, and ammonia., There is no special storage form for protein like, glycogen for carbohydrate or adipose tissue for fat., Protein storage is always accompained by tissue, growth., Amino acid metabolism includes biosynthesis of, amino acids and degradation, conversion of the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 198, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , carbon skeletons of the amino acids to amphibolic, intermediate urea synthesis, and the formation of, a wide variety of physiologically active compounds, such as serotonin., Liver, kidney and several other tissues contain D, and Lamino acid oxidases, active in deamination, of the D or Lamino acids as the case be., Most of the deamination occurs in liver normally., , l, , Biosynthesis of amino acids, l, , l, , l, , Biosynthesis of amino acids takes place in, association with those organic compounds which, occur in the environment in oxidised states such as, SO42–, N2 and NO3., The environmental forms of nitrogen and sulphur, are reduced to metabolically available forms and, are combined with intermediates of carbohydrates, metabolism to synthesize the 20 amino acids,, characteristics of all living form., The collection of free amino acids in the body, (blood) is called amino acid pool. They represent, the relation between the removal and addition of, amino acids., , Glutamic, Dehydrogenase, , ˆˆˆˆˆˆ†, ˆ a Ketoglutaric, Glutamic acid + H2O ‡ˆˆˆˆˆ, in Liver ˆ, acid + H + NH3, l, , Protein catabolism, l, l, , The amino acid enters respiratory routes in two, ways—deamination and transmination., Liver plays an important role in protein, catabolism., , Deamination, l, The first stage in the breakdown of amino acids is, the removal of their nitrogenous groups as ammonia., It is a catabolic process in which the amino group, is removed and convert the amino acid into a keto, acids. This is known as deamination., l, Such deamination results from the action of a variety, of enzymes—which are either oxidative or, hydrolytic., l, Oxidative deamination –, –, Catalyzed by a group of flavin enzymes as, amino acid oxidases which are autooxidizable, flavoproteins i.e. the reduced FMN or FAD is, reoxidised directly by molecular oxygen, forming hydrogen peroxide (H2O2) without, participation of cytochromes or other electron, carriers., –, H2O2 is then split to O2 & N2O by catalase,, which occurs widely in tissues, especially liver., , In the amino acid oxidase reactions, the amino, acid is first dehydrogenated by the flavoprotein, of the oxidase, forming an aamino acid. This, spontaneously adds water, then decomposes, to the corresponding aketo acid with loss of, the aamino nitrogen as NH3., Hydrolytic deamination – In addition to the amino, acid oxidases, there are a number of hydrolytic, enzymes that deaminate specific amino acids,, particularly the sulphurcontaining amino acids,, aspartic and glutamic acids. For example, in the, nonoxidative deamination of glutamic acid, the, enzyme glutamic dehydrogenase removes two, hydrogen atoms from a combination of glutamic, acid and water, with NAD as coenzyme, and a keto, acid is again formed. The reaction is readily, reversible., , l, , l, , l, , l, l, l, , l, , The ammonia liberated by deamination reactions, is n ot allowed to accumulate b ut rap idly, metabolized with the result that very little escapes, into the blood., Blood ammonia is normally 1012mg/100 ml., Incease in blood ammonia is highly toxic to the, central nervous system and may be fatal., Ammonia is toxic to the nervous system and its, accumulation rapidly causes death. Therefore it must, be detoxified to a form which can be readily, removed from the body., Ammonia is converted to urea (in liver), which is, water soluble and is readily excreted via the kidneys, in urine., Liver is the main site of ammonia metabolism., The steps in the synthesis of urea in the liver were, elucidated by Krebs and Henseleit., After deamination, carbon atoms of degraded amino, acids emerge in major metabolic intermediates that, can be converted into glucose or be oxidised by the, citric acid cycle. To economize the metabolic, conversions, the carbon skeletons of twenty diverse, amino acids are funnelled into only 7 molecules:, Pyruvate, Acetyl CoA, Acetoacetyl CoA, a, Ketoglutarate, Succinyl CoA, Fumarate and, Oxaloacetate., On the basis of the amphibolic fates of their carbon
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 199, , ►Ěńńśńďŕ– ▐ĚŚďĐŐńĽřŇ, , skeletons, amino acids are classified into three types:, purely glucogenic, purely ketogenic and glucogenic., , l, , Transamination (Transfer of amino groups), l, The process involves the transfer of the amino group, (–NH2) from a donor amino acid to the recipient, keto acid to form the analogous amino acid and to, produce the keto acid from the original amino donor., The donor amino acid thus becomes a keto acid, and the recipient keto acid becomes an amino acid., The keto acids so formed are normal participants, of glycolysis or Krebs cycle., l, An example of transamination is the formation of, the amino acid alanine by the transfer of the amino, group from glutamic acid to pyruvic acid, in the, course of which aketoglutaric acid is produced., The enzyme involved are transaminases or, aminotransferases., l, Enzymes called ‘transaminases’ or ‘amino, transferases’ catalyze the transfer of the amino group, of an amino acid to an alfa keto acid to form a new, amino acid and a new keto acid., l, Aminotransferases are present in the liver, kidney, and the brain., l, Each enzyme is named in terms of the two amino, acids involved, e.g. glutamicalanine transaminase., l, Pyridoxal phosphate (PLP), the coenzyme form of, vitamin B6, forms the essential part of the active, site of transaminases., Glutamic acid + Pyruvic acid, , Fixation, N 2 , NO 3- ¾¾¾¾, ¾, ® NH 3, Assimilation into, a ketoglutaric acid, , ¾¾¾¾¾¾¾¾® Glutamic acid, , Another example of transamination is, , l, l, , Glutamicaspartic, , l, , l, , In almost all instances of transaminations, glutamic, acid is one of the reacting partners. A specific, aminotransferase promotes each specific, transamination. The alanine and aspartic amino, transferases are the most abundant., Transaminations are reversible, and the equilibrium, constant for all these reactions is close to 1. Hence, the direction in which the reaction proceeds will be, , Assimilation of NH3 into arginine via carbamyl, phosphate: After the initial fixation of NH3, into glutamic acid as given above, three, reactions take place for the synthesis of amino, acid arginine. These reactions are – synthesis, of glutamine, synthesis of carbamyl phosphate,, and arginine synthesis., In adult man (70 kg), about 400 grams of proteins, is synthesized daily and that much is also degraded., Vitamin B6 is involved in the metabolism (especially, catabolism) of amino acids, as a cofactor in, transamination reactions that transfer the nitrogen, from one keto acid (an acid containing a keto group, [CO] in addition to the acid group) to another., The liver is the main site of catabolism for all, essential amino acids, except the branchedchain, amino acids, which are catabolized mainly by, muscle and the kidneys., Disorders of amino acid metabolism include, phenylketonuria, albinism, alkaptonuria, type, 1 tyrosinaemia, nonketotic hyperglycinaemia,, histidinaemia, homocystinuria, and maple syrup, urine disease., , –, , Glutamic acid + Oxaloacetic acid, transaminase, ¾¾¾¾¾¾¾¾¾, ® a Ketoglutaric acid +, pyridoxal phosphate, Aspartic acid, , Transamin ation, with a keto acids, , ¾¾¾¾¾¾¾® other a amino acids, , Glutamicalanine, , ¾¾ ¾ ¾ ¾ ¾ ¾ ¾¾, ® a Ketoglutaric acid +, transaminase,, pyridoxal phosphate, Alanine acid, , governed by the needs of the cell., Significance of transamination are –, –, Transamination provides a means for, redistributing amino nitrogen., –, Transaminations occur in all cells and they, permit any amino acid to be respired via the, citric acid cycle. Actually, certain, transaminations produce keto acids that are, normal components of the citric acid cycle., The common examples are:, Amino acid, Keto acid, (i) Alanine, ®, Pyruvic acid, (ii) Aspartic acid ®, Oxaloacetic acid, (iii)Glutamic acid ®, aKetoglutaric, acid, –, Transaminations, also, carry, out, interconversions of protein with fat., , l, , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 200, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 23, , Cell Reproduction, l, l, , l, , l, l, l, , l, l, , l, , l, l, l, , All cells arise from preexisting cells by process of, cell division., There is a definite balance (ratio) between nucleus, and cytoplasmic mass of cell called karyoplasmic, ratio or nucleocytoplasmic ratio or kernplasma, ratio., Due to continuous cell growth, this balance or, correlation (ratio) is disturbed, which leads to cell, division., Further cell division is also necessary for continuity, of organism or species., The phenomenon of production of daughter cell, from parent cell is known as cell division., A cell born after a division proceeds to grow by, synthesizing new macromolecules and then reaches, a stage where it is ready to divide again., Cell reproduction is more complex in eukaryotes, than in other organisms., The process of cell reproduction has three major, parts. The first part of cell reproduction involves, the replication of the parental cell’s DNA. The, second major issue is the separation of the, duplicated DNA into two equally sized groups of, chromosomes. The third major aspect of cell, reproduction is the physical division of entire cells,, usually called cytokinesis., The division and replication of cells are the basis, for both sexual and asexual reproduction in most, organisms., All those changes which occurs during cell growth, and cell division are collectively called cell cycle., The interval between two division phases is called, interphase., The mechanism of cell reproduction or cell division, is fundamentally similar in all organisms showing, kinship and unity of life., , l, , The different factors controlling cell division are–, cell size, karyoplasmic ratio and mitogens (agents,, factors or substances that trigger cell division)., , CELL CYCLE AND PHASES, l, , l, , l, l, l, l, , l, , l, l, l, l, l, l, , The sequence of events involving growth and, division, a cell undergoes from the time of its, formation by division of the parent cell to its own, division into daughter cells is called cell cycle., Cell cycle is divided broadly into 2 phases – the, Iphase (or interphase) and Mphase (or cell, division phase)., Interphase (also called intermitosis) is the longest, phase in the mitotic cycle., Interphase is the metabolically active stage and, period of intense biosynthetic activity., Repair of damaged DNA sequences also takes place, in the interphase., Interphase is the most suitable period to carry, out FISH (Fluorescence in situ hybridization). FISH, is used for detecting and locating gene mutations, and chromosome abnormalities., The Iphase is further divided into G1 (first growth, phase), S (DNA synthesis phase), and G2 (second, growth phase)., In G1 phase synthesis of protein, RNA, amino, acids, ATP, and nucleotides occur., G1 phase is also called antephase as during this, phase the cell stores ATP for cell division., The decision for cell division occurs in G1 phase., In Sphase synthesis of DNA and histone protein, occurs., S phase is also called invisible stage of Mphase., In G 2 phase synthesis of RNA and protein,, continues and formation of macromolecules for, spindle and organelle formation occurs.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńń– ☻ĚőŕŐęśĘŚĽŐň–, , 201, , Table : History of cell division, 1., , Name of the Scientist, Prevost and Dumas (1824), , 2., , Remak (1841), , 3., , Rudolf Virchow (1855, 1859), , 4., 5., 6., 7., , Strasburger (1873), Boveri and Flemming (18791880), Flemming (1882), Braur, Sutton, VanBenden,, Strasbarger and Winiwater, (18871900), Farmer and Moore (1905), Gregoire, Howard and Pele 1953, Montegomery, Montose J. Moses (1955), , 8., 9., 10., 11., 12., l, l, , l, , l, , l, , l, l, , Contributions, First studied cell division. They described cleavage in the, fertilized egg of frog., Found new cells to develop from preexisting cells while, studying cleavage in eggs. Discovered amitosis (1855), Postulated cell lineage theory that cells arise by division of, preexisting onesomnicellulaecellula., Found that new nuclei develop from preexisting ones., Studied details of somatic cell division., Coined the term ‘Mitosis’., Studied the process of cell division before the formation, of gametes (meiosis), Coined the term “Meiosis”, Differentiated Meiosis I and II, Described cell cycle., Introduced the term synapsis., Synaptonemal complex, , In G2 phase, the quantity of DNA within the cell has, increased to 4C but the cell is still considered diploid., Metabolic activities in regard to growth of, cytoplasm and its constitutents occur during G2, phase., During cell division, oxidative processes are, minimum in Mphase and therefore deficiency of, oxygen has no visible effect on the speed of mitosis., The G0 phase is a period in the cell cycle where, cells exists in a quiscent state. The cells, which are, not to divide further, do not proceed beyond the G1, phase and start undergoing differentiation into, specific types of cells. Such cells are said to be in, G0 Phase to distinguish them from G1 cells which, will soon enter S phase. Some of them, such as, fibroblasts, which help in healing of wounds, grow, and divide again on demand of the body. Some, types of cells do not divide after attaining full, differentiation and finally die. These include nerve, cells, skeletal muscle cells and red blood cells., Cells that are permanent in the G0 phase are, called postmitotic cells. An example of such cells, are neurons., G0 state is the condition of a cell whose division, has been arrested at G1 state., Cells that have permanently stopped dividing due, to age or accumulated DNA damage are said to be, senescent., , l, l, l, , l, , l, , l, l, l, , l, , Cell cycle is regulated by cyclin–dependent, protein kinases., Cyclins are proteins which activate protein kinases, regulating eukaryotic cell cycle., These kinases are synthesized in G2 phase and cause, phosphorylation of proteins of nuclear lamina leading, to breakdown of nuclear membrane in late prophase., p53 is a protein that functions to block the cell, cycle if the DNA is damaged. If the damage is, severe this protein can cause apoptosis (cell death)., p53 levels are increased in damaged cells. This, allows time to repair DNA by blocking the cell, cycle. A p53 mutation is the most frequent mutation, leading to cancer. An extreme case of this is Li, Fraumeni syndrome, where a genetic defect in p53, leads to a high frequency of cancer in affected, individuals., p27 is a protein that binds to cyclin and CdK, blocking entry into S phase., There are a number of cell cycle checkpoints,, beyond which the cell cycle does not proceed., A check on completion of S phase : The cell seems, to monitor the presence of Okazaki fragments on, the lagging strand during DNA replication. The, cell is not permitted to proceed in the cell cycle, until these have disappeared., DNA damage checkpoints sense DNA damage, before the cell enters S phase (a G1 checkpoint);
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńń– ☻ĚőŕŐęśĘŚĽŐň, , l, , l, , l, l, , l, , l, , l, l, , l, , during S phase, and after DNA replication (a G2, checkpoint)., Spindle checkpoints : Some of these that have, been discovered are –, –, Detect any failure of spindle fibres to attach, to kinetochores and arrest the cell in metaphase, (M checkpoint)., –, Detect improper alignment of the spindle itself, and block cytokinesis., –, Trigger apoptosis if the damage is irreparable., The spindle checkpoint blocks entry into anaphase, until all chromosomes are properly attached to the, mitotic spindle., The spindle checkpoint is an active signal produced, by improperly attached kinetochores., The spindle checkpoint blocks anaphase entry by, inhibiting the anaphasepromoting complex., Cell division is absent in RBC and brain cells and, highly specialized cells like muscle and nerve cells., In gymnosperm in development of gametophytes, and embryos, free nuclear division occurs and after, completion of nuclear division wall formation, occurs from periphery towards centre., Actual cell division occurs in Mphase which may, be mitotic or meiotic., Mphase is itself composed of two tightly coupled, process mitosis (in which the cell’s chromosomes, are divided between the two daughter cells) and, cytokinesis (in which the cell’s cytoplasm, physically divides)., Karyokinesis (division of nucleus) is usually, followed by cytokinesis (division of cytoplasm)., , l, l, , l, , Cell division, cell reproduction or cell multiplication, is the process of formation of new or daughter cells, from the preexisting or parent cells., Cell division occurs in three ways – amitosis,, mitosis and meiosis., , Mitosis, l, l, , l, , l, , l, , Amitosis, l, l, l, , In amitosis, division of nucleus occurs without, visible chromosome., Amitosis was discovered by Robert Remak., Amitosis is called direct nuclear division because, of the absence of the formation of spindle and, absence of changes in chromosomes., , Amitosis is an asexual means of reproduction in, bacteria (binary fission) and in yeast cells (budding)., Amitosis is seen in the cartilage cells, in some, degenerating cells of diseased tissues and in the, old tissue, foetal membrane cells etc., , Drawbacks of amitosis, l, Elongated chromatin fibres do not condense to form, chromosomes., l, Elongated chromatin fibres break during, constriction of the nucleus., l, There is no mechanisms for separation and equitable, distribution of daughter chromosomes., l, Amitosis causes unequal distribution of chromatin, material amongst the daughter nuclei., l, It results in structural and functional abnormalities, in the cells., , TYPES OF CELL DIVISION, l, , 203, , l, , l, l, , The cell division that takes place in somatic cells, is mitosis., The site of mitotic cell division in plants are –, meristematic regions like stem tip, root tip,, intercalary meristem, lateral meristem, growth of, embryo leaves, flowers, fruits, seeds etc. In animals, mitosis is found in embryo development and some, restricted regions in the mature form like skin and, bone marrow., Mitosis is the process by which a cell separates its, duplicated genome into two identical halves. It is, generally followed immediately by cytokinesis, which divides the cytoplasm and cell membrane., This results in two identical daughter cells with, a roughly equal distribution of organelles and, other cellular components., Mitosis and cytokinesis together is defined as the, mitotic (M) phase of the cell cycle, the division, of the mother cell into two daughter cells, each the, genetic equivalent of the parent cell., Because cytokinesis usually occurs in conjunction, with mitosis, “mitosis” is often used, interchangeably with “mitotic phase”., Mitosis is called equational division because it, results in the formation of two identical daughter, nuclei., In mitotic division the chromosomes replicates, and are equally distributed into 2 daughter cell., Mitosis is also called indirect nuclear division
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 204, , l, , ŕďőĽę– ĐĽŐńŐĹť, , because of the formation of spindle and visible, changes in chromosomes., Mitosis is divided mainly into two phases :, interphase and division phase., , Phases of mitosis, l, For convenience of study, cell division is divided, into 4 phases prophase, metaphase, anaphase, and telophase., 1. Prophase, l, Early prophase is also called spireme stage. In, this stage chromosomes are overlapping with one, another., l, In mid prophase, the chromosomes appear coiled, and shortened., l, The chromosomes appear to consist of 2, longitudinal fibres called chromatids attached at, the centromere., l, The nuclear membrane dissolves and the, nucleolus degenerates at the end of prophase., l, In animal cell two centrioles are formed from the, centrosome., l, Spindle formation begins at late prophase., 2. Metaphase, l, Metaphase is short and simple., l, Centromeres are arranged in a row in the middle, of the cell during prometaphase of mitosis. But, the arms of chromosomes show deviations., l, During metaphase fibres of spindle apparatus,, made of microtubules, are of three types –, kinetochore microtubules, polar microtubules, and aster microtubules., l, The structure formed by the arrangement of, chromosome at the centre of a cell during meta, phase is called metaphase plate or equatorial, plate., l, Spindle apparatus is formed from the microtubules, of cytoplasm., l, In animal cell, spindle fibres are formed due to, division of centriole where asters are present, so, spindle of animal cell is called amphiaster., l, Spindle of plant centromere cell is called anastral., l, Spindle fibres extending from one pole to the other, are called continuous spindle fibres., l, Fibres extending from a pole to the centromere of, a chromosome are called chromosomal spindle, fibres or discontinuous spindle fibres., l, Fibres which develop between the separating, , l, , l, , l, l, , l, , 3., l, , l, , l, l, l, l, , 4., l, l, l, , l, , centromeres are called interzonal fibres (during, anaphase). Interzonal fibres are also called, interchromosomal fibres., The daughter chromosomes move towards the, opposite poles due to repulsion between, centromere, contraction of spindle fibres and, relaxation of interzonal fibres., Metaphase is the best stage in mitosis for, analysing the chromosomes and to study their, morphology., Graphic representation of a chromosomal, complement of a species is called karyogram., Karyotypic analysis helps in prenatal diagnosis of, chromosomal numerical abnormalities, gene, location and relationship between chromosomal, change and developmental defects., Karyotype is prepared at metaphase of diploid, somatic cells., Anaphase, Anaphase begins with the separation of the, centromeres and the pulling of chromosomes to, opposite poles of the spindle., In anaphase movement, the chromosomes appear, as V, L, J and Ishaped depending upon the, position of centromere and named as metacentric, (centromere is in middle), submetacentric, (centromere is partly middle), acrocentric, (centromere is present at one end of the, chromosome) and telocentric (centromere is at the, apex of the chromosomes)., Division of centromere indicates the separation, of chromatids., At the end of anaphase, two groups of, chromosomes are formed, one at each pole., Chromosomes are shortest at metaphase, while, thickest at anaphase., The number of chromosomes at each pole is equal, to the number of chromosome in the parent nucleus., Telophase, Telophase is a reversal of prophase and, prometaphase events., At telophase chromosome became decondensed, and uncoiled and form chromatin., Nucleolus, nuclear envelope and nucleoplasm is, reformed and hence two daughter nuclei are, formed at two poles during telophase., Sachs reported that temperature influences the, process of karyokinesis (mitosis).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńń– ☻ĚőŕŐęśĘŚĽŐň–, l, l, , l, , l, , l, , Cytokinesis is the division of cytoplasm., Cleavage or furrowing cytokinesis occur in animal, cells where an invagination occur at the equator, which deepens and finally cleaves into 2 daughter, cells and are separated., Plant cytokinesis takes place by two methods, cleavage (usually in lower plants) and cell, plate., In plant cell, cell plate is formed from golgi, apparatus between the two groups of chromosomes., The cell plate grows from the middle towards the, periphery and finally joins the cell wall. The early, cell plate is the middle lamella of the many layered, cell wall., In Saccharomyces small protuberances arise from, cell and part of nucleus after mitosis or amitosis, migrate into the outgrowth to form new cell., Mitotic poisons are inhibitor of cell divisions,, eg: azides and cyanides (inhibit prophase);, colchicine. vinblastin and granosan (inhibit, spindle formation at early metaphase by, inhibiting assembly and polymerization of, microtubular spindle fibres); chalones check, cell division in vivo and in vitro both;, ribonuclease suppresses prophase; and heat, shocks prevents cell division., , Significance of mitosis, l, Essential for growth and development of a, multicellular organism., l, Helps to maintain the stability of chromosome, number, and hence provides genetic stability., l, Method of multiplications of unicellular, organisms., l, Mechanism for repair of old and worn out cells., l, Restores the surface volume ratio of cell., l, Restore the nucleoplasmic index., l, Produces multicellular condition and provides, opportunity for differentiation., l, Repair of body takes place because of addition of, cells by mitosis., Types of mitosis, l, When karyokinesis is not followed by cytokinesis, the division is called free nuclear division., l, Repeated free nuclear divisions result in the, formation of a multinucleate cell or a coenocytic, cell., l, In unicellular organisms, such as Amoeba and yeast,, , l, , l, l, , 205, , mitotic events usually occur within the nuclear, envelope, which remains intact and the nucleus, divides by furrowing along with the cytoplasm., Such a mitosis is called intranuclear., In multicellular organisms, the nuclear envelope, breaks down and the mitosis is termed, extranuclear., Replication of chromosomes without karyokinesis, is called endomitosis (or) endoploidy., Endomitosis results in polyploidy when, chromatids separate from chromosome., , Meiosis, l, , l, , l, l, l, , l, l, l, , l, , l, , Meiosis forms the basis of sexual reproduction, and can only occur in eukaryotes. In meiosis, the, diploid cell’s genome, which is composed of, ordered structures of coiled DNA called, chromosomes, is replicated once and separated, twice, producing four sets of haploid cells each, containing half of the original cell’s, chromosomes. These resultant haploid cells will, fertilize with other haploid cells of the opposite, gender to form a diploid cell again., In meiotic cell division, reduction in chromosome, number occurs, which gives rise to 4 haploid cells,, each having half the number of parental, chromosomes., Meiosis was discovered by Strasburger., Term meiosis was used by Farmer & Moore., If meiosis does not take place in an organism the, chromosome number will be doubled in each, generation., Meiosis must take place in an organism to maintain, the chromosome number constant., The cell which undergoes meiosis is called a, meiocyte., The meiocyte is comparatively large and possesses, a large nucleus. It contains diploid number of, chromosomes which form a network., In animals, the meiocytes are the primary, spermatocytes and primary oocytes present in, the gonads while in plants these are represented by, sporocytes found in the sporogonia., There are three types of meiosis –, –, Zygotic or initial meiosis which occurs, immediately after fertilization in certain, protozoan groups, fungi and some algae;
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 206, , ŕďőĽę– ĐĽŐńŐĹť, , Sporogenetic or intermediate meiosis which, occurs at the time of spore formation in higher, plants; and, –, Gametic or terminal meiosis which occurs, at the time of gametogenesis in a few lower, plants, most animals and many protozoans., Meiosis occurs only in reproductive or germinal, cells., Meiosis consists of 2 divisions meiosis I and, meiosis II., First nuclear division of meiosis is called, meiosis I or reductional division or heterotypic, division., Second nuclear division of meiosis is called, meiosis II or equational division or homotypic, division., Meiosis II is of shorter duration than the typical, mitotic division., –, , l, l, l, , l, , l, , Meiosis I, l, Meiosis I consists of 4 stages – prophase I,, metaphase I, anaphase I and telophase I., 1. Prophase I, l, Prophase I is a lengthy phase when compared to, mitotic prophase., l, Prophase I is divided into 5 subphases. They are, leptotene or leptonema; zygotene or zygonema;, pachytene or pachynema; diplotene or diplonema, and diakinesis., l, A large nucleus is seen in the meiocyte during, leptotene., l, In leptotene the nuclear membrane enlarges, and, chromosomes became distinct., l, Chromosomes appear as long and slender threads, (single threads) bearing bead like structures called, chromomeres during leptotene., l, In many animal cells during leptotene stage all, chromosomes in a cell converge to a common point, near centrosomes (centrioles) through a structure, called attachment plate. It gives a basket like, appearance. This is called bouquet stage, (synizesis)., l, The cells undergoing meiosis have diploid number, of chromosomes and are called homologous, chromosomes., l, During zygotene the chromosomes become shorter, and thicker. Lengthwise pairing of homologous, chromosomes begins., , l, l, l, , l, , l, , l, , l, l, l, l, l, l, l, , l, , l, l, , l, , l, , Each chromosome of the homologous pair is, contributed by either parent., Pairing is exact and takes place chromomere for, chromomere., Paring of homologous chromosomes (maternal, and paternal) is called synapsis or syndesis and, occur in zygotene., The process of attachment of homologous, chromosomes (called synapsis) leads to formation, of bivalents., Synaptonemal complex is formed at the region of, synapsis. This complex has one central and two, lateral longitudinal element which are connected, by lateral element., Each lateral element occurs in between two, chromatids of a chromosome and central element, lies between two homologous chromosomes., Each chromosome of homologous pair have 2, chromatid, known as sister chromatids., Each bivalent pair consists of 4 chromatids which, is called tetrad stage., Pachytene is also known as tetrad stage of meiosis., Pachytene is the longest stage in mammalian, spermatogenesis., It is said to begin when synapsis is completed., The number of bivalents is half the diploid number, of chromosomes., In most species condensation of the chromosomes, increases after zygotene, so that the bivalents appear, as thick threads. Shortening and thickening of the, chromosomes takes place due to longitudinal,, contraction., The two chromatids belonging to the same, chromosome are called sister chromatids and those, belonging to two different homologous pair are, termed as nonsister chromatid., The chromatid is the unit of crossing over., Crossing over is exchange of chromosomal, segments between nonsister chromatids of, homologous pair., Crossing over brings about gene recombinations, or new combination of genes. It also produces, genetic variations., The homologous chromosomes remain attached at, the region of crossing over and these points are, called chiasma. This formation occur in pachytene, stage.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 208, , l, , l, , l, , l, l, l, l, , l, l, , 2., l, , l, , 3., l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Chiasmata are found in the meiosis of almost all, eukaryotic organisms. However, achiasmatic meiosis, (meiosis without chiasma) has been reported in some, organisms, e.g., males of higher Diptera (including, Drosophila), Panorpa (scorpion fly), many mantids, and roaches, some grasshoppers and scorpions., A chiasma formed at the ends of chromosomes is, called terminal chiasma. Chiasmata formed along, the lengths of chromosomes are called interstitial, chiasmata., The homologous chromosomes start separating, (called disjunction) as the nucleoprotein complex, of synapsed chromosomes dissolves. This occurs, in diplotene., Diplotene is the longest and most active subphase, of prophaseI of meiosis., Dictyotene is an arrested diplotene noticed during, oogenesis (oocyte stage) in the foetal development., In diakinesis terminalization of chiasmata occurs., Terminalization is the disappearance of chiasmata, of sliding towards the tips of the chromosomes due, to tight condensation., The degree of terminalization is expressed by the, terminalization coefficient (T)., The nucleolus degenerates and nuclear envelope, disintegrates in diakinesis., Metaphase I, In metaphaseI spindle apparatus appear and the, chromosomes are arranged on equatorial plate, with, the centromeres towards the pole., The spindle is formed. Spindle fibres becomes, attached to the centromeres of the two homologous, chromosomes., Anaphase I, In anaphaseI, the homologous chromosomes break, apart, and this process is termed disjunction., The separated chromosomes are termed as dyads., At the end of anaphaseI, two groups of, chromosomes are produced at two poles, having, half the number of parental chromosome., Because the chromosomes undergo crossing over, during prophase the composition of the separating, homologous chromosomes is different from that of, the chromosomes undergoing synapsis., In each homologous chromosome one chromatid is, unchanged, while the other has undergone mixing, of maternal and paternal sections., , l, , l, , 4., l, , l, , l, , The division of centromeres, which is characteristic, of the anaphase of mitosis, does not take place in, meiosis., Nondisjunction and breakage of chromosomes may, occur during anaphase I due to nondissolution of, chiasmata. It produces chromosomal aberrations,, aneuploidy and polyploidy., Telophase I, In telophaseI polar groups of chromosomes arrange, themselves into haploid nuclei, nucleolus, nuclear, membrane appear at each poles, thus 2 daughter, nuclei are produced., Interkinesis is the stage between telophase I and, prophaseII where chromosomes are elongated,, centrosome undergoes replication but DNA, synthesis does not occurs, protein and RNA, synthesis occurs., It is important for bringing true haploidy., , Meiosis II, l, Meiosis II is essential to separate the chromatids, of univalent chromosomes which differ from each, other in their linkage groups due to crossing over., l, It differs from mitosis in that DNA does not, duplicate but centromere do so., l, Meiosis II is subdivided into 4 phases – prophase II,, metaphase II, anaphase II and telophase II., l, In prophase II nucleolus (nucleoli) and nuclear, envelope degenerates and the chromosomes, shorten a little., l, Centrioles move to the polar regions and are, arranged by spindle fibres., l, In metaphaseII the chromosomes arrange themselves, in the centre with the help of spindle fibres., l, The centromere of each chromosome divides and, chromatids separate, to form daughter, chromosomes in anaphase II., l, At the end of anaphase II, 4 groups of haploid, chromosomes are produced., l, The process ends with telophase II, which is similar, to telophase I, marked by uncoiling, lengthening,, and disappearance of the chromosomes occur as, the disappearance of the microtubules. Nuclear, envelopes reform; cleavage or cell wall formation, eventually produces a total of four daughter cells,, each with a haploid set of chromosomes. Meiosis, is now complete.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►Ěńń– ☻ĚőŕŐęśĘŚĽŐň–, , Ø, , Ø, , l, , l, , l, , l, , Nondisjunction (Bridges), The normal separation of chromosomes in, meiosis 1 or sister chromatids in meiosis II is, termed disjunction. When the separation is not, normal, it is called nondisjunction. This results, in the production of gametes which have either, more or less of the usual amount of genetic, material, and is a common mechanism for trisomy, or monosomy. Nondisjunction can occur in the, meiosis I or meiosis II phases of cellular, reproduction, or during mitosis., This is a cause of several medical conditions in, humans, including –, – Down syndrome trisomy of chromosome 21., – Patau’s syndrome trisomy of chromosome, 13., – Edward syndrome trisomy of chromosome 18., – Klinefelters syndrome an extra X, chromosome in males., – Turner syndrome only one X chromosome, present in females., – XYY syndrome an extra Y chromosome in, males., – Triple X syndrome an extra X chromosome, in females., In successive type, cytokinesis occur after every, nuclear division, meiosis I, and meiosis II, giving, rise to isobilateral tetrads., Simultaneous type occurs only after meiosis II, giving rise to tetrahedral tetrads., Chiasmata and crossing over are the two, exclusive features of meiosis., Chiasmata may be terminal or interstitial. The, chiasmata mark the site of crossing over between, the nonsister chromatids of homologous, chromosomes., , Significance of meiosis, l, Formation of gametes – Meiosis forms gametes, that are essential for sexual reproduction., l, Genetic information – It switches on the genetic, information for the development of gametes or, gametophytes and switches off the sporophytic, information., l, Meiosis facilitates stable sexual reproduction –, Without the halving of ploidy, or chromosome, count, fertilization would result in zygotes that, , l, , l, , l, , 209, , have twice the number of chromosomes than the, zygotes from the previous generation. Successive, generations would have an exponential increase, in chromosome count, resulting in an unwieldy, genome that would cripple the reproductive fitness, of the species., Most importantly, however, meiosis produces, genetic variety in gametes that propagate to, offspring. Recombination and independent, assortment allow for a greater diversity of genotypes, in the population. As a system of creating diversity,, meiosis allows a species to maintain stability under, environmental changes., Crossing over – It introduces new combination of, traits or variations., Mutations – Chromosomal and genomatic, mutations can take place by irregularities of meiotic, divisions. Some of these mutations are useful to, the organism and are perpetuated by natural, selection., Evidence of basic relationship of organisms –, Details of meiosis are essentially similar in the, majority of organisms showing their basic similarity, and relationship., , ABNORMAL CELL GROWTH, l, , l, , l, , l, , Cell division is a gene controlled process. The, telomere of chromosome contains repetitive, sequence of six nucleotide. These regions code for, an enzyme telomerase which control cell division., As cells go on dividing with each division the, number of nucleotides decreases and ultimately cells, stop dividing., Uncontrolled cell division may lead to the formation, of undifferentiated aggregate of cells termed tumor, or neoplasm., Uncontrolled cell division is of the following, types – hyperplasia, hypertrophy, metaplasia,, neoplasia, and Hela cell., Hyperplasia : The increased production and growth, of normal cells in a tissue or organ is termed, hyperplasia. It is an accelerated rate of cell division, resulting from an increased level of cell metabolism., This generally results in an enlargement of tissue, mass and organ size. It occurs only in tissues, capable of mitosis such as the epithelium of skin,, intestine, and glands. Some cells do not divide
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 210, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , and thus can not undergo hyperplasia, for example,, nerve and muscle cells., Hypertrophy : An increase in the size of a tissue, or organ brought about by the enlargement of its, cells is termed hypertrophy. When cells, hypertrophy, components of the cell increase in, number with increased functional capacity to, meeting increased cell needs. Hypertrophy, generally occurs in situations where the organ, or tissue can not adapt to an increased demand, by formation of more cells. This is commonly, seen in cardiac and skeletal muscle cells, which, do not divide to form more cells., Metaplasia : The process of conversion of normal, tissue cells into an abnormal form in response to, stress or injury or infection is termed metaplasia., It is a cellular replacement process., Neoplasia : The new and abnormal development, of cells that may be benign or malignant is termed, , l, , neoplasia. There are two types of neoplasm –, benign and malignant., –, Benign growth: The benign growth is, restricted to a particular site of the body and, the cells never spread out to different parts of, the body, e.g. simple tumor., –, Malignant growth: In malignant growth after, the cells are being formed at a particular site,, the cells move out to different parts of the, body and initiate similar type of growth. The, stage of malignant growth in which the cells, spread out through the body fluid to different, parts of the body is termed metastasis., Malignant growth is also termed cancerous, growth., He La cell : He La cells (an aneuploid epithelial, cells) are cell line culture of first human cancerous, cells donated by Henrietta Lacks from their uterine, carcinoma cells since 1952. These cells are, maintaned for use in studying cellular processes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▒ŕĽĹĽň– Őě– ▌ĽěĚ–, , 211, , Chapter 24, , Origin of Life, l, , l, l, , l, l, , l, , l, , l, , l, , l, , l, , Origin of life is the process by which living, organisms developed from inanimate matter, which, is generally thought to have occurred on Earth, between 3500 and 4000 millions years ago., Methane which has helped develop life on Earth, occurs on Jupiter, Saturn and interstellar space., Origin of life is known as biopoiesis means, biopoiesis is the development of living matter from, complex organic molecules that are themselves, nonliving but self replicating., First life evolved 38004200 million years back., There are several theories about the origin of life., These are – theory of special creations, theory of, eternity, theory of catastrophism, cosmozoic theory, or theory of panspermia, theory of spontaneous, generation and Oparin Haldane theory., Theory of special creation was proposed by, Hebrew et.al. and supported by Father suarez, (Spanish Priest)., According to this theory life was created by, supernatural power either once or at successive, intervals., The theory of eternity of life, also called the steady, state theory, states that the life has ever been in, existence as at present and will continue to be so, for ever, changing only in form. It neither had a, beginning nor will have an end., Steady state theory does not accept the, palaeontological evidence that, presence or, absence of a fossil indicates the origin or extinction, of the species represented and quotes, as an example, the case of coelocanth, Latimeria., According to this theory, scientist like Richter,, Preyer, Helmholtz, Arrhenius, Hoyle, Bondi,, believed that life is immortal., Sudden creation of life from inorganic material was, , l, , l, l, l, , l, , l, , l, , l, , supported by George Cuvier. This theory is called, theory of catastrophism or Catacylsm., According to this theory, the abrupt faunal changes, geologists saw in rock strata were the result of, periodic devastations that wiped out all or most, extant species, each successive period being, repopulated with new kinds of animals and plants., Cosmozoic theory was proposed by Richter, (1865) and supported by Arrhenius (1908)., Cosmozoic theory is also called theory of, panspermia and spore theory., This theory states that life had reached the Earth, from some other heavenly body in the form of, resistant spores of simple organisms (called, cosmozoa) in meteorites or in spaceships., Theory of spontaneous generation or abiogenesis, or autogenesis states that life originated from non, living things in a spontaneous manner. For eg., insects, were believed to originate from dew, frog and toads, from moist soil under the influence of Sun, butterflies, from cheese and fly and maggots from flesh., The theory of abiogenesis was believed and, supported by Thales, Anaximander, Newton,, Descrates & Van Helmont., Theory of spontaneous generation was disproved, by Francesco Redi (1668), Abbe Lazzaro, Spallanzani (1767) and Louis Pasteur (1867)., Francesco Redi (16261698) performed a series, of experiments to disproof the theory. He placed, meat or fish (eel) under clean muslin coverings and, demonstrated that while flies laid eggs on muslin,, maggots or larvae appeared only when those eggs, were transferred to the meat and allowed to hatch., He concluded that maggots develops only from, preexisting flies and were not spontaneously, generated by any other form of material.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 212, , ŕďőĽę– ĐĽŐńŐĹť–, , In 1765, Abbe Spallanzani, an Italian scholar, prepared flasks of meat broth which were boiled, for several hours and then sealed. The broth, remained clear for months, and when the seals were, broken and the broth tested, it was shown to be free, of microbes., Louis Pasteur (in 1864) used a swanneck flask, and prepared a meat broth in this flask, and boiled, it for several hours. He then left the flask unsealed, on a laboratory bench. The flask was not sealed,, and there was a free exchange of air with the, environment, so the system did not lack oxygen., Still, the swanneck remained free of microbial, contamination for months, because, their swan, necks were shaped so to trap viable microbial, particles and to allow only air to enter the flask., After several months when he broke the neck of, one of these flasks, contamination by air and, proliferation of microorganisms in the fluid ensued., This experiment thus disproved the concept of, spontaneous generation completely., Pasteur is famous for germ theory of disease., The process of destroying all living organisms is, called sterilization., Sterilization is done to surgical instruments to kill, all the pathogens present on the instrument., All three scientists (Redi, Spallanzani and Pasteur), developed theory of biogenesis., According to theory of biogenesis life originated, from preexisting life., The modern hypothesis of origin of life was, formulated by Haeckel. This idea was elaborated, in the chemical theory by two workers, , l, , l, , l, l, l, l, l, l, , l, , l, , l, , l, , l, l, , independently : a Russian biochemist A. I. Oparin, (in 1923) and an English biologist J.B.S. Haldane, (in 1928). It was summarized by Oparin in his book :, The ‘Origin of Life’, published as an English edition, (in 1938)., Oparin and Haldane state that –, –, Spontaneous generation of life under the, present environmental conditions is not, possible., –, Earth’s surface and atmosphere during the first, billion years of its existence were radically, different from today’s conditions., –, Initial atmosphere of Earth was reduced, –, First life arose from a collection of chemicals, through a progressive series of chemical, reactions., –, Solar radiation, heat radiated by earth &, lightning provided energy for evolution of, molecules., Modern theory of origin of life was propounded, by Oparin which is based upon chemical, evolution., The Oparin Haldane theory (also called, protobiogenesis) was experimentally supported, by Stanley Miller in 1953., Modern views regarding the origin of life include, origin of Earth & its primitive atmosphere;, chemical evolution (chemogeny) and biological, evolution., It is considered that the Earth was formed about, 4600 million years ago., Four basic requirements for the life to arise are, primitive atmosphere [with little or no oxygen, (O2)],, , Table : Some notable milestones in origin of life showing approximate origins in million years., S. No., 1., , Origin of, Universe, , 2., 3., 4., 5., 6., 7., 8., 9., 10., 11., 12., , Solar system, Earth, A biotic origin of anaerobic life, Anaerobic photosynthetic bacteria, Beginning of traces of oxygen, Oxygen producing photosynthetic cyanobacteria, Eukaryotes with a nucleus, First land plants, First mammals, Man (Homo sapiens), Traces of O2, , Time in million years, 10,00020,000 [through big bang, hemaitre (1931) of cosmic material], 4,600, 4,600, 4,200, 3,5003,800, 3,800, 3,3003,500, 1,6001,200, 459, 220, 3.5, 3.8
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▒ŕĽĹĽň– Őě– ▌ĽěĚ, , l, , l, , l, l, l, , l, l, , l, , l, , l, , l, l, , l, , l, l, , l, , right chemicals (including water, various inorganic, ions & organic molecules); an energy source, and, infinite time., The energy needed for the chemical evolution on, the primitive Earth mainly came from solar, radiation & cosmic rays; electric discharges;, volcanic eruptions, heat etc., Early earth had innumerable free atoms of all those, elements which are essential for formation of, protoplasm., The lightest atoms of nitrogen, hydrogen, oxygen, etc. formed the primitive atmosphere., Free atoms combined to form molecules and simple, inorganic compounds., Primitive atmosphere was reducing atmosphere, because hydrogen atoms (most numerous and most, reactive) combined with all available oxygen atoms, to form water and leaving no free oxygen., Water and ammonia were probably the first, compound molecules of primitive earth., Chemical evolution (also called chemogeny), involves the synthesis of simple organic, molecules., With slight lowering of the surface temperature of, the earth, the lighter elements interacted to form, water, methane (first organic compound),, ammonia, CO2, HCN etc., The early compounds interacted and produced, simple organic compounds such as simple sugars,, nitrogenous bases, amino acids, glycerol etc., Simple organic compounds were formed with the, help of external sources (UV rays, cosmic rays,, lightning etc) acting on the mixtures., Experimental evidence for formation of simple, organic compounds was given by Stanley Miller., The OparinHaldane theory suggests that complex, organic molecules would have been formed through, a series of chemical reactions in the earth’s, ‘primordial soup’., Synthesis of complex organic compounds from their, simple constituent molecules were experimentally, proved by Stanley Miller with the help of, ‘simulation experiments’., The apparatus used by Miller is called ‘Spark, discharge apparatus’., Miller passed an electric discharge in a mixture of, methane, ammonia, hydrogen (ratio 2 : 1 : 2) and, water (steam)., By simulation experiments, Miller synthesized, , l, l, l, , l, , l, , l, , l, l, l, , l, , l, l, l, l, l, , 213, , about 15 amino acids and identified as glycine,, alanine, glutamic acid and aspartic acid., The energy used in the Miller Urey experiment was, electric spark., The first simplest organic compounds to arise were, methane, ethylene, acetylene, etc. (hydrocarbons)., Carried to the earth’s surface by rainwater, the, simple organic compounds then would have, accumulated in the ocean as a warm, dilute “soup”., The oceanic water rich in mixture of organic, compounds was termed by J.B.S. Haldane (1920), as ‘hot dilute soup of organic substances, or, ‘Prebiotic soup’., The large organic molecules which were synthesized, abiotically on primitive earth later came together, and formed large colloidal aggregates., Protenoids are protein like substance formed by, polymerization of aminoacids under inorganic, conditions such as heating to over 140ºC., The formation of protein molecules can be, considered a land mark in the origin of life., Colloidal aggregates were named microspheres by, Sydney Fox and coacervates by Oparin., The model proposed by S.Fox of protenoid, microsphere for protocells is widely accepted because, of its following significances : (1) Such protenoid, microspheres arise from monomers, rather than from, polymers obtained from organisms already in the, biota, as is true for the usual experiments with, coacervate droplets. (2) This model suggests that, protenoids are informational and it shows the origin, of communication which may be intercellular or, intergenerational communication., Nucleic acid, formed by the polymerization of, nucleotides, are the basis of life as these represents, the genetic material of an organism and is the, molecular basis of heredity., Nucleoproteins gave most probably the first sign, of life., Biological evolution (or biogeny) involves, formation of prokaryotes to eukaryotes., More complex coacervates and microspheres, function as precells or prebionts., The first living form named protocell or eobiont, or protobiont, originated in the primitive ocean., Amino acids, sugars, glycerol and fatty acids gave, rise to polymers, which may have assembled into, spherical structures called protobionts.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 214, , ŕďőĽę– ĐĽŐńŐĹť–, , 1. Free Atoms ...................................... H (Hydrogen), C (Carbon), N (Nitrogen), 2. Inorganic Molecules ......................, , H2 (Hydrogen), H2O (Water), CH4 (Methane), NH3 (Ammonia),, é CO2 (Carbon dioxide), êë, 3. Simple Organic Molecules ............. CH4, H2O, Sugars, Fatty Acids, Glycerol, é CH4, H2O, NH3, Amino Acids, (Precursors), ê CH4, H2O, NH3, HCN, Nitrogenous Bases (Purines, Pyri, ê, midines), ê, 4. Complex Organic Molecules ......... ë Sugar + Sugar, Polysaccharides, Fats, of biological origin, é Fatty Acids + Glycerol, ê Amino Acid + Amino Acid, Proteins, ê Nitrogen Bases + Sugars + Phosphates, Nucleotides, Ade, ê, nosine Phosphates, ê, Nucleic, Acids, Nucleotides, +, Nucleotides, ê, 5. Coacervates (Oparin) ..................... êë Aggregates of large complex organic molecules capable of growth, and division, 6. Eobionts ............................................ Nucleic acid—controlled coacervates, 7. Free gene .......................................... Self replicating nucleoprotein complex., 8. First Primitive cells ........................ Lipidprotein membranebound units with enzymecontrolled, metabolism and nucleic acid regulation without organised nucleus, Prokaryotes ........ Chemoheterotrophs and anaerobic (due to, absence of free oxygen from the environment), Eukaryotic Cells (With well organised nucleus), Multicellular organisms, Flow chart : Main steps in the origin of life according to the Oparin–Haldane theory and Modern views., l, , l, , l, l, l, , l, , Protocells were prokaryotic unicells which had, naked DNA, protein manufacturing machinery,, mode of energy liberation and its utilization., Protobionts made of polypeptides are called, microspheres, those of lipids are called liposomes, and those of combinations of polypeptides, nucleic, acids and polysaccharides are called coacervates., The origin of prokaryotes were probably from, protocell., The first prokaryotes were anaerobes and, chemoheterotrophs., Chemoautotrophs were formed when environment, over the earth became cooler., The organisms performing chemosynthesis are, called chemoautotrophs., , l, , l, l, , l, l, , l, , Simple one celled organisms somewhat similar to, today’s cyanobacteria were present on earth about, 3600 million years ago., Atmosphere become richer in oxygen due to, photoautotrophs., Free living eukaryotic cell like organisms originated, in the ancient ocean presumably about 1.5 billion, years ago., Primitive eukaryotes led to the evolution of, protists, plants and animals., The oxygen present in the modern atmosphere must, have been liberated as a result of photosynthesis of, green plants., The most important condition for the origin of, life is the presence of water because life can, originate from abiogenetic materials in water.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▒ŕĽĹĽň– Őě– ▌ĽěĚ–, l, l, l, , l, , l, l, l, , There is no life on the moon because there is no, water., Life originated in the ocean (water) presumably, about 3.7 billion years ago in precambrian era., The prokaryotes evolved before the eukaryotes. The, oldest known fossil cells are about the same size, as modern prokaryotes., Some of the oldest known fossil cells appear as, parts of stromatolites, which are formed today from, sediments and photosynthetic prokaryotes., The earliest autotrophs must have been anaerobic, chemoautotrophs., The first organisms to give off oxygen were, probably cyanobacteria., When a primitive bacterium is exposed to oxygen, gas, it dies., , l, l, l, l, l, , l, l, , 215, , Organisms that can grow with or without oxygen, gas are called facultative anaerobes., Organisms that are poisoned by oxygen gas are, obligate anaerobes., Organisms that cannot grow without oxygen gas, are obligate aerobes., Prokaryotes were limited in genetic variability, because they reproduced by binary fission., Haeckel (1894) proposed to create a separate, subkingdom protista to include all unicellular, eukaryotic plants and animals., Prokaryotes are more diverse than eukaryotes in, terms of metabolism., Of the planets of our solar system, only Mars is, supposed to have life, but no evidence of life has, yet been found by the scientists.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 216, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 25, , Relationship Among, Organisms & Evidences of, Evolution, l, l, , l, , l, l, , All living organism have arisen through the, evolutionary process and shows diversity., Although microbes, plants and animals show a great, diversity, these shows a number of life processes, which are common to all organisms like all are, formed of living protoplasm, derive energy and, matter from their environment, maintain, homeostasis through a number of metabolic process,, etc., Evolution is the formation of newer types of, organisms from the preexisting ones through, modification. Evolution is, therefore, often called, descent with modification (Darwin, 1859)., Evolution has occurred through mutation,, natural, selection and isolation., Term evolution was coined by Herbert Spencer, and has been derived from latin word ‘evolvere’, Ø, Ø, Ø, Ø, , Ø, , Ø, Ø, , l, , l, l, , which means unfold and literally means the process, of continuous change., Evolution is an orderly change from one condition, to another, eg when planets and stars change in, between their birth and death, then it is called as, stellar evolution., When matters, elements change from time then it, is called as inorganic evolution., Evolution is of several kinds, like –, –, Progressive evolution : formation of more, complex, elaborate and specialized structures, from simpler ones., –, Retrogressive evolution : development of, simpler and less elaborate forms from complex, ones., –, Microevolution : development of minute, changes due to gene mutations and, , Historical Aspect of Evolution—Ancient Thoughts, According to Indian mythology, Brahma created various forms of life in one stroke., According to Anaximander, a Greek philosopher of 6th century B.C., water was the material source, for evolution., Heraclitus (510 B.C.) proposed the idea of struggle among living organisms., Plato (428348 B.C.) proposed that each species has an unchanging ideal form (eidos) in his idealistic, concept. According to him, all earthly representatives are imperfect imitations of such true essence of, an ideal unseen world. God is perfect and everything that existed on Earth was His ideas., Aristotle (384322 B.C.) constructed a “Scala Naturae”, also called Ladder of Nature or Great, chain of Being, in which he grouped the living organisms from simpler ones to the most complex ones., So he proposed a gradual transition from imperfect to perfect., The ancient Indian texts of philosophy and Ayurveda deal with the origin of life., Manu’s texts in Sanskrit, ManuSamhita or ManuSmriti (200 A.D.) also made a mention about, evolution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚńŐňřĺĽő– ○ŇŐňĹ– ▒ŕĹďňĽřŇř– ·– ◄ŢĽęĚňĘĚř– Őě– ◄ŢŐńśŚĽŐň, , l, , l, , recombinations. The changes occur below the, level of species., –, Macroevolution : development of large, changes like formation of new species and, genera due to mutation causing large scale, changes in chromosomes., –, Megaevolution : large change giving rise to, new families, orders, classes etc., –, Parallel evolution : independent formation, of similar traits by related groups of organisms., –, Convergent evolution (adaptive convergence) :, formation of similar traits by unrelated groups, of organisms as wings in insects, bird and bats., –, Divergent evolution (adaptive radiation) :, formation of different structures from a, common ancestral form, e.g., forelimbs in, horse, bat and human beings., –, Coevolution : evolutionary changes in one, or more species in response to changes in other, species of the same community., There are many types of evidences which, supports the process of organic evolution. These, evidences are – anatomical or morphological;, embryological; palaeontological; physiological, or biochemical; cytological; molecular;, biogeographical; taxonomic and from genetics;, animal breeding, behaviour, hosts and parasites,, formation of new species and experimental, production of new species., Study of functional anatomy is known as tectology., , l, , l, , l, , l, , l, , ANATOMICAL OR MORPHOLOGICAL, EVIDENCES, l, , l, , l, , l, , l, , Comparative study of the morphology & anatomy, of groups of animals or plants shows that certain, structural features are basically similar. These, features includes – body organization & gradual, modification., Morphological and anatomical evidences include, homologous & analogous organs, connecting, links, vestigial organs and atavisms., Organs having similar embryonic origin &, construction but differing in external form and, functions are called as homologous organs., Homologous organs are found in forms showing, adaptive radiation from a common ancestor, so, these give evidence of divergent evolution., The vertebrate forelimbs, insect legs, insect mouth, , l, , l, l, , l, , l, , 217, , parts, vertebrate epidermal derivatives, tail and, vertebral column and thorns of Bougainvillea and, tendrils of Passiflora are some common examples, of homologous organs., The forelimbs of these animals (seal, bird, bat,, horse and man) have the same general function of, locomotion but have different shapes and bring, about different types of locomotion. They are used, for – swimming in seal, flying in bird and bat,, running in horse and grasping in man., Legs of all insects consists of 5 parts, named as, coxa, trochanter, femur, tibia and 15jointed tarsus,, and are used for locomotion. They all have different, form and perform different specific functions in, different insects. The same basic structure of the, legs shows that all the insects have a common, ancestor. The variation is due to adaptive, modification during the evolution of the group., Vertebrate tail is composed of vertebral column,, blood vessels, nerves, muscles and skin. It lacks, coelom and viscera. Tail is used for swimming in, fish, mud puppy (amphibian), crocodile, and whale;, for holding onto objects in seahorse, chamaeleon,, scaly ant eater and new world monkeys; as a, balancing organ in kangaroo; to keep off flies in, cattle; and for defence in spiny tailed lizard and, wall lizard., Homologies are of two types – phylogenetic (eg, hand of man and leg of horse) and serial homology, (invertebrates)., Analogous organ are those organ which have the, similar function and are superficially appear similar, and are different in fundamental structure and, embryonic origin., Examples of analogous organs are – wings of, insects, birds and bats (meant for flying) ;, phylloclades, cladodes and phyllodes (perform the, function of leaf as photosynthesis)., The analogous organs are the result of convergent, or parallel evolution in separate lineage., There are different modified roots, stems and leaves., Sweet potato is an underground tuberous root and, potato is an underground stem but the modifications, are meant for storage of food. These are therefore, examples of analogous organs., The organisms which possess the characters of two, different groups are called connecting links and, shows the possible path of evolution., Connecting links are the living intermediate forms.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 218, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Important connecting links., Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, Ø, , l, , l, , l, , l, , l, l, , Chimaera (Rabbit or rat fish), Virus, Euglena, Proterospongia, Neopilina, Peripatus, Balanoglossus, Lungfish Protopterus, Latimeria, Seymouria, Archaeopteryx, Spiny ant eater (Echidna), Duck Billed Platypus, Lycaehaps, , –, –, –, –, –, –, –, –, –, –, –, –, –, –, , Missing link are the transitional forms between, two groups of organisms occurring only in the fossil, state, eg Archaeopteryx., Vestigial organs are the useless and functionless, degenerate structures which were large and, functional in some other animals. They are, rudimentary, relatively smaller in size and do not, function., Some of the vestigial organs in animals are given, as follows : vermiform appendix, coccyx, plica, semilunaris, pinna muscles and wisdom teeth in, man; rudiments of hindlimbs in python and boa;, pelvic girdle in whales; splint bones (vestigial 2nd, & 4th digit of fore and hindlimb) of horse; wings, of kiwi and eyes in cave animals., Atavism is the sudden reappearance of those, ancestral characteristic in an organism or in the, organisms of a group, which do not occur normally, or which represent the reminiscent of normal, structures possessed by the individuals of other, groups., Atavism is also known as reversion., Examples of atavisms are –, –, Cervical fistula : In man only one pharyngeal, pouch perforates to form an opening from the, pharynx to the exterior in the form of the, external ear canal and Eustachian tube. But,, rarely neck may possess an additional opening, representing the cervical fistula., –, Tail : Tail is absent in man but occassionally, a human baby is born with a short fleshy tail., –, Hairs on the body and face, –, Homodont dentition in cetaceans : Cetaceans, , Between, Between, Between, Between, Between, Between, Between, Between, Between, Between, Between, Between, Between, Between, , l, , l, l, , l, , l, , cartilaginous and bony fishes, nonliving and living, plants and animals, protozoa and porifera, mollusca and annelida, annelida and arthropoda, echinoderms and chordates, fishes and amphibia, fishes and amphibia, amphibia and reptiles, reptilia and birds, reptilia and mammalia, reptilia and mammalia, reptilia and mammalia, , are mammals with heterodont dentition. But, piscivorous cetaceous possess simple conical, homodont teeth. Their ancestors are known to, possess heterodont teeth of mammals. This is, true reversal of evolution., The principle of atavism was proposed by L., Dollo and is called Dollo’s law. It states that living, organisms do exhibit evolutionary irreversibility., Types of atavism are – family atavism, race, atavism & atavism of teratology., Family atavism includes the transmission of, individual characteristic or characteristics within, the members of a family in latent condition for, several generation and their sudden reappearance, in the offsprings after a number of generation. This, phenomenon is controlled at gene level and can be, explained by simple Mendelian laws of inheritance., Race atavism includes those cases of reversal where, one or more characters of one race appear in the, individual of another race, e.g. profuse growth of, hair on the body & face of Irish dogman etc., Atavism of teratology includes the appearance in, a race of such abnormal characters, which were, normal in other supposedly ancestral races. Eg., appearance of cervical fistula in man which actually, corresponds to gill slits etc., , EVIDENCES FROM EMBRYOLOGY, l, , Embryological development reveals a unity of, plan. Embryos of the vertebrate series exhibit many, features that are absent in the adults. For example,, all the embryo’s a vertebrates including human develops, a row of vestigial gill slits just behind the head.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , l, , l, , l, , l, , l, , l, , l, , 1. Similarity in early development., 2. Resemblance among vertebrate, embryo’s in shape and structure., 3. Recapitulation theory or biogenetic law, by ErnstHaeckel stating that an animal, in its development from egg to adult, repeats or recapitulates in a condensed, form the stages through which its, ancestors have passed in the course of, evolution i.e . ontogeny repeats, phylogeny., 4. Temporary nonfunctional embryonic, structures., 5. Retrogressive metamorphosis, 6. Neoteny., , Evidences for embryology are based on the, comparative study of the embryos of various, animals (See the above flow chart)., In 1828, Von Baer put forward Baer law. E., Haeckel later called it the biogenetic law (in 1868)., The view was summarised as ontogeny recapitulates, phylogeny. Ontogeny is the life history of an, organism while phylogeny is the evolutionary, history of the race of that organisms., The recapitulation theory not only supports the, concept of organic evolution, but also discloses, the stages in the evolution of an animal., Recapitulation is seen in invertebrates also, eg., adult insects have three pairs of walking legs but, in embryo, each body segment has one pair of, primordia of legs. This shows that insects have, evolved from an ancestor having segmentally, arranged appendages., Certain animals show complicated larval forms and, simple adults, e.g. ascidians, parasitic copepods,, parasite like Sacculina. In retrogressive, metamorphosis, due to parasitic habit, adult organs, are highly reduced., In some animals (eg. axolotl larva of Ambystoma), the larva fails to undergo metamorphosis. It, develops gonads, attains sexual maturity and starts, reproduction. This is called neoteny or, paedogenesis., Retention of primitive or larval features provides, evidences in favour of evolution that under, specifically favourable circumstances natural, selection favours retention of primitive or larval, characteristics., , Egs., , Evidences from, embryology, , ☻ĚńŐňřĺĽő– ○ŇŐňĹ– ▒ŕĹďňĽřŇř– ·– ◄ŢĽęĚňĘĚř– Őě– ◄ŢŐńśŚĽŐň–, , 219, , 1. Larva of Herdamania shows characters of, chordates (presence of notochord), 2. Change of a fish like embryo of human to a, seventh month human foetus resembling a, baby ape to a human baby., 3. Origin of gymnosperms from pteridophyte, like ancestor., 4. Fish like tadpole of frog shows it has evolved, from fish like ancestor., 5. The protonema of moss and fern shows an, algal ancestory., 6. The presence of primordia of leg in each, segment of the embryo of insect shows that, they arose from an ancestor having, segmentally arranged appendages., , Ecogeographical Rules–Size, Shape and Colour, Ø, Cope’s Law : In the course of evolution,, there is tendency in animals to increase in, size, eg dinosaurs., Ø, Bergman’s Law : Warm blooded animals, are larger in size in the colder regions as, compared to hotter parts., Ø, Allen’s Law : Extremities like tails and ears, become smaller in colder areas., Ø, Gloger’s Rule : Warm blooded animal have, more melanin in hot wet areas but develop, yellowred pigment in hot dry areas., Ø, Rapoport’s Rule : Species adapted to cooler, climates have a wide range of latitudinal, distribution than the species adapted to, warmer climates., Ø, Jordan’s Rule : Fishes of colder waters have, larger size with more vertebrae than the fishes, of warmer waters., Ø, Dollo’s Law : States that evolution is, irreversible. Proposed by L.Dollo in 1893., Ø, Gause’s Law (Gause 1934) or the competitive, exclusion principle (Hardin 1960) : It states, that the two species having the same ecological, requirements cannot continue to occupy, indefinitely the same habitat., , PALAEONTOLOGICAL EVIDENCES, l, , Palaeontology is the study of the past life based, on fossil records. Their study reveals the existence, of life in past and illustrate the course of evolution., The organic remains like bones, hairs, nails, claws,, shells or impressions of the organisms found in, rocks are called fossils.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 220, , l, , l, l, , l, , l, , l, , l, , l, l, l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Father of palaeontology is Italian Leonard de, Vinci (15421519) while founder of modern, palaeontology is Cuvier (1769 1832)., Fossils are remains of extinct organisms buried, and preserved by natural process., The science of palaeontology links biology with, geology and is concerned with finding cataloguing, and interpreting evidences., The study of fossil plants is called palaeobotany, while the study of fossil animals is called, palaeozoology., Charles Darwin was the first to show that fossils, provides direct evidence for organic evolution, because it deals with the actual organisms which, lived in the past., The different methods of fossilization (a continuous, process) are– intact preservation, petrifaction,, moulds & casts, impression, mummies, tracks &, trails etc., The media in which the fossil occur include, sedimentary rocks, amber, asphalt, volcanic ash,, ice, peat bogs, sand and mud., Age of fossils is determined by dating the rocks, in which fossils occurs., The dating of rocks are called geochronology and, dating system is called clocks of rocks., Rocks are of three types :, –, Sedimentary rocks formed by gradual settling, down of fragments in regions such as lakes or, sea, eg. conglomerate, sandstone, shale,, limestone, gypsum etc., –, Igneous rocks formed by the cooling down, and solidification of molten material of the, earth ., –, Metamorphic rocks are actually sedimentary, rocks which are changed by heat and pressure,, eg. schist, gneiss, slate & marble., The method for determining the age of rocks or of, the fossils are– carbon dating method (discovered, by W.F Libby); radioactive clock method (uranium, lead method) which is based upon the disintegrating, property of radioactive elements [proposed by, Boltwood (1907)], and potassium argon method., Half life period of C14 is about 5600 years., The common radioactive elements which lose their, radioactivity and change into their nonradioactive, isotopes at a fixed rate are:, Potassium40 ® Argon40, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Carbon14 ® Nitrogen14, Uranium238 ® Lead207, Rubidium87 ® Strontium87, Thorium232 ® Lead206, Halflife of K40 is 1.3×109 years., PotassiumArgon method is useful because, potassium is a common element found in all sorts, of rocks. Potassium decays into argon extremely, slowly., PotassiumArgon method has recently been used, to determine the age of hominid fossils in East, Africa., Living fossils are those plants and animals which, have become extinct excepting one or two, representatives, eg Sphenodon, Ginkgo, Equisetum, etc., Death and disappearance (extinction) of large, groups of plants and animals over a short span of, time is called mass extinction., Mass extinction may be due to the crash of a meteor, or comet with earth (impact theory) or to the, drifting, coalescing and breaking apart of continents, (continent movement theory). Mass extinctions, shape the overall pattern of macroevolution., The largest mass extinction came at the end of, the Permian, about 250 million years ago. This, coincides with the formation of Pangaea II, when, all the World’s continents were brought together, by plate tectonics., The most wellknown extinction occurred at the, boundary between the cretaceous and tertiary, periods. This called the K/T Boundary and is dated, at around 65 million years ago. This extinction, eradicated the dinosaurs., Fossil/Forests/Parks are largesized exposures of, fossil bearing rocks, dug out and conserved by, experts so as to give glimpses of what sorts of, plants and animals existed in that period., Birbal Sahni Institute of Palaeobotany at, Lucknow is exclusively engaged in study of fossil, plants., Some national fossil parks are – (i) 50 million, years old fossil forest in intertrappean lava, sediments at Mandla in M.P. (ii) 100 million years, old fossil forest in Rajmahal Hills, Bihar, (iii) 260, million years old coal forming forest of Orissa. (iv), National fossil park. Tiruvakkarai is found in South, ArcotDistrict of Tamil Nadu. Fossilized trunks of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚńŐňřĺĽő– ○ŇŐňĹ– ▒ŕĹďňĽřŇř– ·– ◄ŢĽęĚňĘĚř– Őě– ◄ŢŐńśŚĽŐň, , 221, , Table : Types of fossils, their formation and examples., Fossil, , Fossilization process, , Example, , Entire organism, , Frozen into ice during glaciation, , Entire organism, , Encased in the hardened resin (amber) of coniferous Insect exoskeletons found in oligocene, trees, rocks in Baltic coast, , Entire organism, , Encased in tar, , Entire organism, , Trapped in acidic bogs; lack of bacterial and fungal ‘Mummies’ found in bogs and peat in, activity prevents total decomposition, Scandinavia, , Hard skeletal, materials, , Trapped by sedimentary sand and clay which form Bones, shells and teeth (very common, sedimentary rocks, e.g. limestone, sandstone and slit in British Isles), , Moulds and casts, , Hard materials trapped as above. Sediments harden, to rock. The skeleton dissolves leaving its, impression as a mould of the organism. This can be, infilled with fine materials which harden to form, a cast. Great detail is thus preserved, , Petrifaction, , Gradual replacement by watercarried mineral Silica replacements of the echinoderm, deposits, such as silica, pyrites. calcium carbonate Micraster, or carbon. Slow infilling as organism decomposes, producing fine detail, , Impressions, , Impressions of remains of organisms in finegrained Feathers of Archaeopteryx in Upper, sediments on which they died, Jurassic. Jellyfish in Cambrian found in, British Columbia. Carboniferous leaf, impressions, , Imprints, , Footprints, trails, tracks and tunnels of various Dinosaur footprints and tail scrapings, organisms made in mud are rapidly baked and filled indicate size and posture of organisms, in with sand and covered by further sediments, , Coprolites, , Faecal pellets prevented from decomposing, later Coenozoic mammalian remains, compressed in sedimentary rock. Often contain, evidence of food eaten, e.g. teeth and scales, , tree, twenty million years old are kept in the, Children Park, Guindy, Chennai., Geological time scale, l, Geological time scale is a chronological order or, history of evolution based upon the study of fossils., l, Geologists have divided the history of the earth, into eras, the periods and epochs., l, The precambrian is very long period of time. It, comprises about 87% of the geological time scale., , Woolly mammoths found in siberian, permaforst (25000 years ago), , ‘Mummies’ of mammals and birds found, in asphalt lakes of California, , l, , l, l, , l, , Gastropods from Portland Stone, Jurassic., Casts of giant horsetails (Calamites) of, carboniferous forest. Internal casts of, molluscs shells showing muscle, attachment points, Fossils of Pompeii city,, which was buried by volcanic ash from, mount vasuvius in AD 79, presents, moulds & cast of men and their domestic, animals., , Palaeozoic and mesozoic eras are subdivided into, periods but coenozoic is divided into periods and, epochs., During ordovician the vertebrates originated, the, first fish was ostracoderm., First reptiles appeared during carboniferous, period of palaeozoic era from stem reptiles called, ‘cotylosaurs’, the ancestral genus being Seymouria., North America was the main centre of dinosaur, evolution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 222, , l, l, l, , l, l, l, l, l, l, l, l, l, , l, l, l, l, l, l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , First indication of fishes appeared in cambrian, period., In devonian, diversification of fishes and, evolution of amphibia occurred., The large devonian is characterised by the, appearance of the first land vertebrates. These, animals were called stegocephalians., In pensylvanian, amphibians became dominant, on land, and appearance of first reptiles occurred., In triassic, transition of reptiles to mammals, occurred., In jurassic period, there were dominance of, dinosaur on earth., First toothed bird appeared in jurassic period., Toothed bird as well as dinosaur became extinct, in cretaceous period., Evolutionary explosion of mammals occurred in, palaeocene period., First man like apes appeared in miocene., In pleistocene, extinction of many large mammals, occurred and also referred to as age of man., Recent epoch (the period of last 10000 years of, earths history) is the age of man and where the, development of human cultures occurred., Elephants of pleistocene period are commonly, known as woolly mammoths., Elephants have originated from some common, proboscidean sirenean ancestor., True elephants belonging to the genus Loxodonta, and Elephas appeared in pliocene., True camels belonging to the genera Camelus,, appeared in latter portion of coenozoic era., Mesozoic era is known as era of intermediate life, and “age of reptiles or dinosaurs”., The phylogeny of horse has been traced from the, fossils discovered from the tertiary rocks of, North America., The first known horse like animal which forms the, starting point in the equine evolution is, Hyracotherium (also called eohippus). It is, commonly known as “dawn horse”., Merychippus (ruminant horse) in upper miocene,, marked the completion of transition from, browsing to grazing., Modern horse, Equus is the direct descendent of, Pliohippus., The first representative of Equus appeared in, late pliocene and during pleistocene achieved world, wide distribution., , Evolutioury sequence of horse, Eohippus, Eocene period, Merychippus, (Miocene period), , Mesohippus, (Oligocene period), Pliohippus, (Pliocene period), Equus, (Pliocene period), , l, , l, , l, , l, l, l, l, , Recent epoch – Age of man and limbs., (Holocene), Pliocene, – Age of mammals, birds and, angiosperms., Cretaceous, – Age of reptiles, and, gymnosperms., Jurassic, – Period of dinosaurs., Permian, – Age of amphibians and ferns., Devonion, – Age of fish., Silurian, – Age of higher invertebrates., , BIOGEOGRAPHICAL EVIDENCES, l, l, , l, l, l, , l, , l, l, , l, , Biogeography is the study of distribution of, animals and plants in different parts of the earth., A.R. Wallace (an English Naturalist) divided earth, into six biogeographic realms – palaeoarctic,, oriental, ethiopian, australian, nearctic, and, neotropical., Wallace line is an imaginary line between oriental, and australian realms., Two zoogeographical regions separated by high, mountain ranges are palaearctic and oriental., Prototherians, the most primitive mammals which, provide an evidence of organic evolution from, geographical distribution, are found in Australia., Charles Darwin during his voyage around the, world studied the fauna and flora of Galapagos, islands (off the west coast of south America)., Galapagos islands are called ‘a living laboratory, of evolution’., Darwin studied 20 related varieties of the bird, belonging to family Geospizidae which are different, in shape and size of beak. These birds are now, called ‘Darwin’s finches’., Some years after Wallace’s line, Weber drew an, imaginary line on the map between the oriental, and Australian region, because it was considered, to divide the fauna of two regions better than, Wallace’s line. The Weber’s line is further east than, Wallace’s line.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚńŐňřĺĽő– ○ŇŐňĹ– ▒ŕĹďňĽřŇř– ·– ◄ŢĽęĚňĘĚř– Őě– ◄ŢŐńśŚĽŐň–, l, , l, , Wallacea is a transitional area between Wallace’s, line and Weber’s line in which some of the animals, of both the regions are found. Thus the islands i.e.,, Celebes, Flores and Lombok lying between the two, lines, are neither the geologically part of oriental, region nor part of Australian region., Biogeographical evidences are based on –, –, Discontinuous distribution : descendants of, a common ancestor inhabit different continents, so mutated and slightly different but closely, related species of the same genus, eg alligator,, mangolicas, Tulip sassafras etc., –, Restricted distribution : the continent has, peculiar flora and fauna, eg. pouched animals, in Australia., –, Life on oceanic island : the animals and plants, of oceanic islands resemble those of mainland, yet include distinct species, eg. Darwin finches, of Galapagos islands and the large sized, Inguana & tortoises., –, Convergent or parallel evolution : in this, natural selection can induce animals of two, different groups to adapt similar habitats for, survival, eg., marsupials., , PHYSIOLOGICAL OR BIOCHEMICAL, EVIDENCES, l, l, , l, , l, , l, l, , Comparative biochemistry also shows relationship, among the animals., The aspects of biochemistry that indicate, biochemical affinity are – metabolic processes,, enzymes, hormones, blood and lymph, blood, proteins, blood groups, and molecular homology., The metabolic processes, such as digestion,, biosynthesis, respiration, muscle contraction and, transmission of nerve impulses, occur almost in a, similar manner in all animals., The enzymes are essentially alike in their nature and, action in most animals, for example, trypsin is found, in many animals from sponges to man. This shows, that all animals are related to one another., The hormones resemble in their chemical nature, and function in all the vertebrates., Thyroxine plays a role in the metamorphosis of, tadpole into a frog. If the thyroid glands are, removed, the tadpole fails to turn into a frog. Such, a larva starts metamorphosis if fed on thyroid gland, of another animal., , l, , l, , l, , l, , l, l, , l, , 223, , The blood and lymph fluids are similar in their, composition and physiological role in all vertebrates., This indicates relationship among the vertebrates., The blood proteins of various mammals are similar, to a large extent, but are sharply distinguishable, from those of other vertebrates. The blood protein, tests have shown that the man is nearest the great, apes (gorilla and chimpanzee), and next nearest, in, order, are the old world monkeys, the new world, monkeys and the tarsiers. The same is indicated by, the anatomical facts. Thus, the blood protein tests, reveal man’s genetic relationship., Four blood groups: A, B, AB and O, occur in, humans. The blood groups A and B are found in, apes but not in monkeys. This suggests that human, beings are more closely related to apes than to, monkeys, though all the three have a common, ancestory. The same is shown by blood protein tests, mentioned earlier., The occurrence of similar biochemicals in animals, is called biochemical homology just as anatomical, homology shown by similarity in organs and tissues., Similarity among animals at the molecular level is, called molecular homology., Human DNA differs in only 1.8% of its base pairs, from chimpanzee DNA, and there is no difference, between the two in the amino acid sequence for the, protein cytochrome C. Close relationship indicated, by these sequences conforms to that shown by other, means such as anatomical or fossil evidence., Physiology of excretion in vertebrates clearly, indicates that they have been evolved gradually, from simple forms to complex ones. The, nitrogenous waste in many fishes (e.g., bony fishes), is in the form of ammonia, in case of amphibia it, is urea as amphibia are more evolved and adapted, for life both in water and on land., , TAXONOMICAL EVIDENCES, l, , l, , Taxonomy is the study of the theory, practice and, rules of classification of living and extinct, organisms., The naming, description, and classification of a given, organism draws an evidence from a number of fields, like classical taxonomy (based on morphology and, anatomy), cytotaxonomy (compares the size, shape, and number of chromosomes of different organism),
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 224, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , and numerical taxonomy (uses mathematical, procedures to assess similarities and differences and, establish taxonomic groups)., In the present system of classification different, systemic levels or taxons are employed, like species,, genus, family, order, class, phylum etc., Different species possessing similar features are, included in a genus. Several genera with certain, common characters are grouped into a family., Similarly families form orders, classes and phyla., The classification further shows the grading of, different phyla in the order of increasing complexity, of organisation., Thus classification reveals a positive relationship, between different animals which is due to their, descent from a common stock., , EVIDENCES FROM GENETICS, l, , Genetics is the study of heredity, the transmission, of parental characters to the offspring., , l, l, , l, , l, , l, , A number of sudden inheritable variations are called, mutations., In mutation new genetic material is created which, never existed before. Mutations provide raw material, for evolution and can give rise to new species., Hereditary variations also occur due to genetic, recombination. The latter causes hybridization., Examples of hybridization and mutations are, available which show that evolution has taken place., Pattern of transmission of characters is also similar, in various organisms. It shows interrelationship, among different living beings., Man has developed many varieties of useful animals, (e.g., cows, ancon sheep, horses, hornless cattles, etc.) and crops (e.g., wheat, rice, cotton, etc.). Some, varieties of fruits like mango, citrus, etc. have also, been improved. Hybridization and induction of, polyploidy has given rise to new plants like, Triticale, Raphanobrassica. Such studies have, provided useful evidence concerning the evolution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♀ĺĚŐŕĽĚř– Őě– ◄ŢŐńśŚĽŐň–, , 225, , Chapter 26, , Theories of Evolution, l, , l, l, , l, , Evolution is the process of gradual development, from a simple unorganized condition into a complex, organized form., The process of evolution is continuous, taking place, even now., The concept of organic evolution postulates that:, –, Organisms that appeared earlier were simpler., –, Earlier organisms have gradually changed into, existing complex organisms., –, All organisms are interrelated because of, common origin., Four main theories to explain the theories of, evolution are–Lamarck’s theory of inheritence, of acquired character; Darwin’s theory of, natural selection; mutation theories by Hugo de, Vries and modern concept of evolution., , LAMARCKISM OR LAMARCK’S, THEORY, l, , l, , l, , In 1809 French biologist, Jean Baptist de Lamarck, (17441829) explained this theory, in his famous, book Philosphie Zoologique. He was originally a, botanist but in later life became a zoologist., Lamarckism is popularly known as theory of, inheritance of acquired characters or theory of, use and disuse organs., Propositions of Lamarckism are , –, Internal vital force It tends to change the, size and form of different organisms, generally, making them larger and more complex., –, Effects of environment Variations in the, environmental factors such as temperature,, light, pressure, humidity, wind etc affect the, living things and produce changes in their, bodies., , New needs New needs produce a new, movement in the body that brings about, modification of existing organs and formation, of new organs., It is also known as doctrines of desires or, appetency., –, Use and disuse of organs Constant use of, an organ makes it more efficient and, specialized. Disuse of an organ brings about, degeneration., –, Inheritance of acquired character The, traits acquired due to the above reasons passed, on to the next generation. After several, generation, it gives rise to a new species., Long neck and high forelimbs of giraffe, developed due to their stretching for obtaining, foliage from trees when ground vegetation become, sparse is the prime example of Lamarckism., Lamarckism cannot be accepted fully. Weismann, (1883 1885) and Payne (1911) criticised his, theory of inheritance of acquired characters., Neo Lamarckism is an attempted revival of, Lamarckism by modifying it and finding evidences, for direct effect of environment on germ cells and, the effect of somatic cells on germ cells., Features of Neo Lamarckism are–, –, It refers to the modified version of Lamarck’s, theory (Lamarck’s views + new facts)., –, It does not include factors like inner will and, use and disuse of organs etc., –, It differentiates between somatic cells and, germ cells., –, It holds that only the variations affecting, germ cells are inheritable., The theory of germplasm (Weismann, 1892) states, that inheritance of characters from parents to, –, , l, , l, , l, , l, , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 226, , l, , l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , offspring is mediated through germplasm which, continues generation after generation hence it is, known as theory of continuity of germplasm., Lamarckian postulate of use and disuse of organs, is supported by:, –, Fairly developed and strong biceps of, blacksmith,, –, Elongated limbless body of snake,, –, Bottom dwelling flatfish whose larvae have, normal eyes while in adults eyes migrate to, one side of the head., Some other examples of use and disuse of organs, are:, –, Lengthening of neck of giraffe,, –, Rudimentary eyes of cave dwellers,, –, Vestigial organs of living animals,, –, Webbed feet of swimming birds., Sumner’s experiments on white mice, Kammerer’s, experiment on Proteus anguinus and Tower’s, experiments on potato beetle proved the effect of, environment and temperature bringing about, inheritance of acquired characters., The greatest blow to lamarckism came from the, work of the German scientist August Weismann., NeoLamarckians believe that only those, characters, whatever be their origin and nature,, that could affect germplasm are heritable and others, are not., Objections to Lamarckism–, –, August Weismann conducted experiments of, cutting the tails of rats for 80 generations but, tailless rats were never born., –, Nose boring and ear boring Indian women to, wear ornaments has been in a practice for, several generations but this acquired character, is not inherited. Similarly circumcision, practiced by some communities for last several, centuries is not inherited., –, The small feet of Chinese women confined by, using wooden shoes are never inherited,, similarly the strong muscles of an athlete,, wrestler are not inherited., , l, l, , l, l, , l, , l, , l, , l, , DARWINISM OR DARWIN’S THEORY, l, , Darwinisms is the term coined for the explanation, offered by Darwin for the origin of species by, natural selection., , l, , Darwin gave the biological world a master key that, unlocked the previous intricacies about evolution., The theory of natural selection was announced, on June 30, 1858 by the English naturalist Charles, Darwin (18091882) and Alfred Russel Wallace, (18231913)., This theory is also known as Darwin Wallace theory., Darwinism was published in 1859, in the book, “The Origin of Species by Means of Natural, selection”., The theory of natural selection is based on the, following factors :, –, Rapid multiplication and limited food and, space which leads to struggle for existence., –, Struggle for existence and variations which, leads to natural selection or survival of the, fittest., –, Natural selection and inheritance of useful, variation over many generation which leads, to formation of new species., The struggle for existence is threefold for every, individual :, –, Intraspecific struggle : This is between the, individuals of the same species. This is the, keenest form of struggle as the needs of the, individuals of the same species are identical., –, Interspecific struggle : This is the struggle, between the individuals of different species., This struggle is illustrated by the efforts of a, snake for catching a rat, and of the rat for, escape., –, Environmental struggle : This is the struggle, of the animals with the changes in, environmental factors, such as heat, cold,, drought, flood, storm, famine, light etc., Evidence of Darwinism can be shown by, entomophily. Many pollinating insects have, proboscis length exactly matching the position of, nectary in the flower. This can develop gradually, through natural selection., Industrial melanism (appearance of dark or, melanic forms in some organisms like moths in the, industrial regions) is the appropriate example of, natural selection., Inheritance of small variations, perpetuation of, vestigial organs, overspecialization of organs, go against Darwinism.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♀ĺĚŐŕĽĚř– Őě– ◄ŢŐńśŚĽŐň, , Darwinism passed these 2 phases –, Romantic period For about 40 years from, the enunciation of theory of Natural Selection, by Darwin., l, Agnostic period Period of criticism of, ‘Natural Selection’ for about 30 years due to, continuous variations, pangenesis and arrival, of the fittest., Darwin’s theory fails to explain inheritance of, small variations, perpetuation of vestigial organs,, overspecialization of organs., Darwin was British naturalist; in 1831 at the age, of 22 he was appointed upon a world survey ship, of British government, H.M.S Beagle., Alfred Russel Wallace (1823–1913) also travelled, widely. Evolutionary ideas similar to those of, Darwin developed independently in Wallace’s mind., Both Darwin and Wallace jointly propounded, the ‘Theory of Natural selection’., The thinking of both Darwin and Wallace was, greatly influenced by essays on ‘Principles of, population’ written by T.R.Malthus in 1798., Malthus in his essays on population has said that food, increases in arithmetic progression while number of, animals increases in geometric progression., Darwin’s thinking was also influenced by Charles, Lyell’s (1832) essays on ‘Principles of Geology’., Darwin’s theory is based on the following five, principles:, –, Overproduction, –, Struggle for existence, –, Variations and their inheritance, –, Survival of fittest, –, Natural selection and species formation, Continuity of existence of the fittest was called, ‘survival of fittest’ by Herbert Spencer while, Darwin called it natural selection., Darwin and Wallace published a joint paper titled, ‘Origin of Species’ in 1858’., Some drawbacks of Darwin’s theory are:, –, He considered minute fluctuating variations, as principal factors., –, He did not distinguish between somatic and, germinal variations., One major criticism against Darwin’s theory, was his failure to give a satisfactory explanation, for variations., Neo Darwinism is refinement of original theory, of natural selection to remove objections., , l, , l, , l, , l, , l, , l, l, , l, , l, l, , l, , l, l, , l, , l, , l, l, l, , l, l, , l, , l, , l, , l, , l, , 227, , Important features of Neo Darwinism are –, –, It is a modification of Darwinism in the light, of genetic research., –, It incorporates causes of variation., –, It considers only genetic variations (mutations), inheritable and raw material for evolution., –, Unit of evolution is a population in this, concept., –, Natural selection is referred to as differential, reproduction, leading to changes in gene, frequency., –, It considers reproductive isolation as an, essential factor in speciation., According to NeoDarwinism both mutations and, natural selection are responsible for evolution., The chief NeoDarwinians are Weismann, Mendel, and de Vries., NeoDarwinians believe that the main causes of, difference in members of a species are – difference, in genetic pattern; and influence of different, environment., Resistance of mosquitoes to DDT and sickle cell, anaemia are also examples of natural selection., The Lederberg replica plating technique, demonstrated the adaptation to be a result of the pre, existing mutant forms of bacteria. It supported, Darwinism and illustrated that the introduction of, penicillin (a change in the environment) gave a, selective advantage to the already present penicillin, resistant bacteria over the penicillin sensitive bacteria., Supplementary theories of Darwinism are–, artificial selection, sexual selection and theory, of pangenesis., To explain the various nonadaptive variations, found in domesticated plants and animals he, proposed the concept of artificial selection., Artificial selection is practised for better crop, varieties and in domestic animals by selective, breeding., Sexual selection : Secondary sexual characters, do not play any significant role in the struggle for, existence. Darwin concluded that modes of origin, of secondary sexual characters are beyond the, purview of natural selection., His theory (of sexual selection) is based on these, assumptions :, –, In general males are more abundant than the, females, so there is competition among males, for females.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 228, , ŕďőĽę– ĐĽŐńŐĹť, , l, , l, , l, , Females often choose the males with brilliant, colours or ornamentation., So, in this struggle animals with superior qualities, will be favoured and others get eliminated., To explain the transmission of characters from, generation to generation, Darwin proposed, ‘pangenesis theory’ in 1868., According to theory of pangenesis every somatic, cells produces gemmules and the actual germ, cells are the sites of collections of gemmules, coming from different somatic cells. This theory, has been completely discarded., Objections to Darwinism–, –, It does not explain the adaptability of certain, organs, in their initial stages which are of use, to the organism only in perfectly developed, condition, e.g. protective colouration, mimicry,, electric organs of fishes etc., –, It does not account for the occurrence of, vestigial organs, over specialisation (antlers in, Irish deers, tusks in Mammoth), degeneration, and regeneration of certain organs., –, It does not make any distinction between, heritable and nonheritable variations. He, referred mutations in the process of evolution, as sports of nature., –, If species have evolved by natural selection, of small and useful variations, a number of, transitional forms must be met with, but such, forms are not found in several cases., –, Sterility of hybrids (e.g. mule) and the, occurrence of neutral flowers in plants are not, explained by the theory of natural selection., , –, , –, , l, l, l, l, l, l, l, , SYNTHETIC THEORY, l, , l, l, , l, , MUTATION THEORY, l, , l, , The mutation theory was put forward in 1901 by, Hugo de Vries, a Dutch botanist, to explain the, mechanism of evolution., Features of mutation theory are–, –, Mutations form the raw material for evolution., –, Mutations appear suddenly and produce, their effect immediately., –, Mutants are markedly different from the, parents and there are no intermediate stages, between the two., –, Same mutations can appear in several, individuals of a species., –, Mutations can appear in all directions., , All mutations have a genetic basis and are,, therefore, inheritable., –, A single mutation may produce a new species., –, Nature selects beneficial mutations and, eliminates lethal mutations., –, Evolution is a discontinuous or jerky process., The plant on which de Vries had experimented was, Oenothera lamarckiana (Evening primrose)., The mutation observed by de Vries in Oenothera, essentially was chromosomal number variant., Mutations are discontinuous variations, called ‘sports’, by Darwin and ‘saltatory variations’ by Bateson., Role of mutations in evolution is genetic variations., Mutations are due to changes in chromosomes,, genes or DNA., To be a successful event for evolution, a mutation, must occur in germplasm DNA., Mutations are the changes which may or may not, be inherited., , l, , l, l, , Dobzhansky (1937) in his book ‘Genetics and, Origin of Species’ provided the initial basis of, synthetic theory., ‘Modern Synthetic Theory of Evolution’ was, designated by Huxley in 1942., Some of the important workers who have, contributed to the modern synthetic theory are: Th., Dobzhansky, R.A. Fischer, J.B.S. Haldane,, Sewall Wright, Ernst Mayr and G.L. Stebbins., According to synthetic theory there are five basic, factors involved in the process of organic evolution, These are: gene mutations; changes in, chromosome structure and number; genetic, recombinations; natural selection; and, reproductive isolation., The first three factors are responsible for providing, genetic variability, the last two are responsible, for giving direction to the evolutionary processes., The most accepted and recent theory of organic, evolution is the synthetic theory., Modern concept of evolution is a modification of, Darwin’s theory of natural selection by replacing, favourable variation with genetic variation or, mutation. It is often called neo darwinism or, synthetic theory also., , Genetic variation, l, , Genetic variation form the raw material of, evolution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♀ĺĚŐŕĽĚř– Őě– ◄ŢŐńśŚĽŐň–, l, , l, , l, l, , l, , l, l, , l, , Causes of genetic variation are – environmental, factors (including light, temperature, food,, humidity etc) and genetic factors (migration, non–, random mating, genetic drift, mutation, gene, recombination & hybridization)., The removal of alleles from one population or, addition of alleles into another population is called, gene flow or gene migration., Nonrandom mating results in a deviation from, the Hardy Weinberg distribution., The HardyWeinberg Equilibrium Principle,, which was proposed by G. H. Hardy and W., Weinberg, independently, in 1908, describes that, under certain conditions of stability allelic, frequencies remain constant from generation to, generation in sexually reproducing organisms., This means that, if all other factors remain constant,, the frequency of particular genes and alleles will, remain constant in a population through, generations. This kind of stability at the genetic, level is called genetic equilibrium., HardyWeinberg Principle gives the geneticists a, tool to determine when evolution is occurring., Population geneticists use this principle to calculate, a starting point allele frequency and then compare, it to frequencies measured at some future time., In other words, evolution is a departure from Hardy, Weinberg Equilibrium., , l, , l, , l, l, l, , l, , l, l, , 229, , Genetic drift is the change in number and frequency, of genes in small isolated population due to, intensive inbreeding causing permanent fixation of, some alleles, disappearance of a number of alleles, and change in frequency of others., Genetic drift in a new colony is called founder, effect because only a few founders carrying a small, fraction of genetic variability of the parent, poputation begin the colony., The theory of genetic drift was developed by, geneticist Sewell Wright in 1930., It is also called Sewell Wright effect or scattering, of variability., Genetic drift always influences frequencies of, alleles and is inversily proportional to the size of, population., Drastic shortterm reduction of population size, caused by natural disasters, disease, or predators, may result in (by chance) the survivors representing, only a small portion of the original gene pool. Even, when the population increases to its original size,, a portion of its original genetic diversity remains, lost. This feature, termed a genetic bottleneck, is, a problem with many endangered species., The bottleneck effect prevents most genotypes from, participating in production of next generation., Mutation is the major source of genetic variation., It alters the base sequence of a gene., , Three types of mutations, Gene mutations, Chromosomal aberrations, Chromosomal numerical, (Changes in sequence, (Changes in structure of, mutations, (Changes in number of chromosomes), of nucleotides in DNA), chromosomes), 4 types, 2 types, 3 types, 1. Deletion or Deficiency, 1. Deletion, (a) Terminal, 2. Addition or Insertion, Aneuploidy, Euploidy, (b) Intercalary, 3. Substitution or Replacements, (Gain or loss of one or, (Gain or loss of one or, 2. Duplication, (a) Transitions, two chromosomes), more genomes), (a) Tandem, (b) Transversions, 1. Hypoploidy, 1. Hypoploidy, (c) Tautomerism, (b) Reverse, (a) Monosomy, 2. Polyploidy, 3. Translocation, (b) Nullisomy, (a) Autopolyploidy, (a) Simple, 2. Hyperploidy, (b) Allopolyploidy, (b) Reciprocal, (a) Trisomy, 4. Inversion, (b) Tetrasomy, (a) Paracentric, (b) Pericentric, , Flow chart : Types of mutations.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 230, , l, l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Recombination is the process of bringing together, new combinations of existing genes and alleles., Hybridization is a method of mixing the genes of, two populations. It can occur by migration of a, section of a population of a new place or by cross, breeding by man. It changes the gene frequencies, and alters the phenotypes of the offspring., Natural selection is the process of differential, survival and reproduction that inevitably leads to, changes in allele frequencies over time as those, individuals who are the most fit survive and leave, more offsprings., Biologist recognize three major categories of natural, selection based on its effect on the population over, time – stabilizing selection, directional selection, and disruptive selection., Stabilizing or balancing selection leads to the, elimination of organisms having overspecialized, characters and maintains homogenous population, which is genetically constant. It favours the average, or normal phenotypes, while eliminates the, individuals with extreme expressions., –, For example, house sparrows killed in a, severe snowstorm in New York were found to, have wings markedly longer or shorter than, the mean., In directional or progressive selection, the, population changes towards one particular direction, alongwith change in environment. As environment, is undergoing a continuous change, the organisms, having acquired new characters survive and others, are eliminated gradually., –, For examples,, (a) Industrial melanism In this, number of the, light coloured moth (Biston betularia), decreased gradually while that of the melanic, moths (B. carbonaria) increase showing, directional selection. It provides a well studied, example of directional selection from nature., (b) DDTresistant mosquitoes., (c) Resistance of bacteria to drugs., Disruptive selection is a type of natural selection, which favours extreme expressions of certain traits, to increase variance in a population. It breaks a, homogenous population into many adaptive forms., It results in balanced polymorphism., This kind of selection is rare and eliminates most, , of the members with mean expression so, producing two peaks in the distribution of a trait., Example. A clear example is the different beak, sizes of the African firebellied seedcracker finch, Pyronestes ostrinus., , Speciation & Reproductive isolation, l, l, l, l, , l, , l, l, , l, , l, , l, , l, , l, , l, , Speciation is the phenomenon of formation of, new species from the preexisting ones., Speciation is allopatric if new species develops, from a spatially isolated population., Speciation is sympatric if new species develops, from a segment of population., Breeding species is a group of organisms, capable of interbreeding and producing fertile, offspring., Ecological species is a group of organisms sharing, the same ecological niche; no two species can, share the same ecological niche., Genetic species is a group of organisms showing, close similarity in genetic karyotype., Evolutionary species is a group of organisms shar, ing a unique collection of structural and functional, characteristics., Phyletic speciation is the transformation of a, species with the passage of time due to piling up, of variations., Gradual speciation is slow transformation of an, isolated population or populations into new species, due to gradual accumulation of variations., Reproductive isolation is the segregation of the, population of a species into smaller units or sections, by certain mechanism, so as to prevent interbreeding, among them and help in maintaining their hereditary, integrity., Reproductive isolation between species may be, maintained by one or more of several mechanism, collectively called premating isolating mechanism, & post mating isolating mechanisms., Premating isolating mechanism include –, geographicial, ecological, temporal, behavioural,, mechanical and post mating isolating mechanisms, include gametic incompatibility, hybrid inviability, and hybrid infertility., In geographic isolation two population of the same, species are separated by some physical or, geographic barriers or they occupy different, geographic areas.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 231, , ♀ĺĚŐŕĽĚř– Őě– ◄ŢŐńśŚĽŐň–, l, , l, , l, , l, , Climatic isolation In the absence of any geographic, barrier, the abrupt climatic differences within the, range of distribution of a species are found to produce, isolation of its members into units., Seasonal or temporal isolation Differences in, the breeding season prevent mating and, interbreeding among the individuals of different, populations or of different species., Habitat isolation or ecological or environmental, isolation is caused due to differences in the, habits and habitats of organisms such as food, and physiological requirements and place of, living., Ethological isolation refers to the barriers to, mating among the individuals of different species, , l, , l, , l, l, , l, , due to differences in their courtship behaviour., In mechanical isolation the complex structure of, genitalia in many animals does not permit, copulation among different species., In physiological isolation certain species are, established only on the basis of some physiological, differences developed between them., Gametic incompatibility is the inability of sperm, from one species to fertilise eggs of another species., Hybrid inviability is the failure of a hybrid, offspring of two different species to survive to, maturity., Hybrid infertility is reduced fertility (often, complete sterility) in hybrid offspring of two, different species., , Table : Types of isolation with their cause and examples., Cause, , Types of Isolation, , Examples, , Mechanical isolation, , Differences in morphology of and, genital organs. Mechanism include, the inability of the sperm to bind to, egg in animals or the female, reproductive organ of a plant, preventing the wrong pollinator from, landing., , Insect pollinated species., , Behavioural isolation, (Ethological isolation), , Behavioural differences in courtship,, nest building, dancing., , Stickle backs (fishes). Closely related, grey tree frog and pine woods tree frog., , Seasonal isolation, , Differences in time of sexual maturity,, breeding season prevent mating and, interbreeding., , Plants and invertebrates and insects., , Gametic isolation, , Due to external and internal, fertilization, , Sea urchin, , Mating inability, Interspecific interbreeding., , ––, , Hybrid sterility, , Interspecific sterility due to, gene mutation, , Hybrid breakdown, , ––, , Mule fail to reproduce (they are, reproductively sterile but otherwise, healthy and vigorous)., Tetraploid species of Gossypium, hirsutum etc produces fertile and, vigorous F1 hybrids but in F2 generation, the hybrids are inviable., , Genetic isolation include, Incompatibility, Hybrid inviability, , Warwick and Berry (1949) showed that, the cross between goat and sheep, produce normal embryos but they die, much before birth
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 232, , ŕďőĽę– ĐĽŐńŐĹť, , POLYMORPHISM, l, , l, , l, l, , l, , l, , Ford (1984) defined polymorphism ‘as the occur, rence together in the same locality of two or more, distinct forms of individuals in the same popula, tion or species., Salient features of polymorphism are –, –, It is due to the existence of more than two, types of genotypes., –, Different forms are adapted to different types, of environments, –, All Mendelian populations are polymorphic, –, Increases the efficiency in exploitation of, resources of the environment., –, Helps the species to survive efficiently in a, variety of environments., Type of polymorphism are– balanced polymor, phism and transient polymorphism., In balanced polymorphism, individuals with two, or more forms (morphs) coexist in the same popu, lation of a species in stable environment and show, almost constant ratio. It means that in a popula, tion showing balanced polymorphism, the geno, typic frequencies of various forms occur at equi, librium. There can be following reasons for this, genetic equilibrium –, –, There is balance of selective forces so that no, forms tend to be eliminated or both the alleles, are maintained at appreciable frequencies in, the population., –, Each form (morph) has a selective advantage, of equal intensity., –, None of the forms has selective advantage, over others., –, Heterozygotes are at a selective advantage (i.e., heterozyote superiority)., –, The rare or the rarest allelomorph is, advantageous. As it becomes common its, advantage decreases and it is converted into, a disadvantage., Examples of balanced polymorphism are – sickle, cell anaemia, ABO blood group, Taysach’s disease,, polymorphisms in land snail and Drosophila, polymorpha., Sickle cell anaemia, –, In human beings, the persons exhibiting sickle, cell anaemia have R.B.Cs which become, distorted and sickleshaped in oxygen deficiency., The sickleshaped RBCs are fragile and clog the, , –, , –, , –, , –, , blood vessels which leads to necrosis of various, tissues and damage to organs. This causes severe, anaemia and heart failure., This disease was discovered by the American, physician James B. Herrick (1904) who, examined an anaemic West Indian black, student in Chicago., James V. Neel (1940) established that sickle, cell anaemia is inherited as a simple Mendelian, character –, (a) Normal haemoglobin is produced by, two dominant genes HbA/HbA., (b) Sickle cell anaemic patients have both, the genes recessive Hbs/Hbs., (c) Persons heterozygous for these alleles, (HbA/Hbs) exhibit sickle cell trait. These, have low capacity of carrying oxygen, and posses both kinds of haemoglobin, in nearly equal quantities., In normal human population natural selection, tends to eliminate gene Hb s from the, population. But A. C. Allison (1959) found, that the frequency of gene Hbs is unusually, high in areas prone to malaria in East Africa,, where Hbs gene frequency reaches as high as, 20% or more. In some African tribes, its, frequency is as high as 40%. Allison (1959), explained that high frequency of Hbs gene is, due to selective advantage of heterozygotes, (HbA/Hbs)., In malaria infested areas, sickle cell, heterozygotes (HbA/Hbs) or the carriers are, resistant to malarial infection and are less, infected with the parasite than the homozygous, dominant nonsicklers. Thus the heterozygotes, have better chances of survival than the normal, homozygotes. This advantage of heterozygotes, results in stable polymorphism for gene Hbs., In West Africa, there is a third allelomorph, Hb c which produces another abnormal, haemoglobin – C. The homozygote Hbc/Hbc, suffers from severe anaemia similar to Hbs/, Hbs. The heterozygotes Hbs/Hbc also suffer, from anaemia, but heterozygotes HbA/Hbc are, at an advantage over homozygotes Hbc/Hbc., The above two cases strongly support the view, that the polymorophism for Hb gene is, maintained by natural selection in malaria, infested areas.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♀ĺĚŐŕĽĚř– Őě– ◄ŢŐńśŚĽŐň–, l, , l, , l, , l, , ABO blood groups – In human population, the, existence of A, B, AB and O blood groups are, also examples of balanced polymorphism. Persons, of blood group O have a greater life expectancy, than those of other blood groups, but are prone, to duodenal ulcer., TaySach’s Disease – This disease is common in, children of Jewish heritage, because 1 out of 40, Jewish persons is a heterozygote whereas 1 out, of 380 nonJewish persons is a heterozygous, carrier. This is because the grandchildren of, persons suffering from TaySach’s disease were, resistant to pulmonary tuberculosis in Bethesda,, Maryland. The incidence of Jewish tuberculosis, patients from eastern Europe is relatively high., This finding indicates that the heterozygous carrier, of TaySach’s disease is resistant to pulmonary, tuberculosis., Polymorphism in land sail – Cain, Currey and, Shephered (1954) studied balanced polymorphism, in common land snail, Cepaea nemoralis. Their, shells exhibit polymorphism in colour and band, patterns. The colour polymorphism in these snails, is maintained by selection and the selection force, is predation. These snails are predated upon by, thrushes and the visually conspicuous forms were, at a disadvantage –, –, In areas with uniform background like, grasslands or woodlands with decaying leaves,, the unbanded pink, yellow and brown shells, or single banded shells were particularly, common because of selective advantage., –, In areas with tangled and mottled ground cover, as in rough pasture or hedgerows, the dark, banded shells had a selective advantage., –, Yellow shells with 5bands were common, among rough green herbage. Less green was, the background, the less were the number of, yellow shells., Drosophila polymorpha – The population of D., polymorpha presents three types of colouration of, their abdomen. These arelight colour, dark colour, and intermediate colour. The light colour is due, to recessive genes (aa) in homozygous state and, , l, , l, , l, l, , l, , l, , 233, , dark colour due to homozygous dominant genes, (AA). The heterozygotes with intermediate colour, are most abundant. It means heterozygous flies, have some adaptive advantage., Balanced polymorphism is important in evolution, because it permits variability in the population., This variability helps the population to react rapidly, to an environmental change and to avoid extinction, or to pave way to origin of new species. Thus, balanced polymorphism represents stablizing, selection., Transient polymorphism is found in populations, undergoing a strong selection pressure and one, form or morph is being strongly favoured and the, other is getting eliminated. Thus transient poly, morphism lasts for a short period, because poly, morphism exists till the disadvantageous form is, either completely eliminated or is reduced to such, a low frequency that it is only retained due to, recurrent mutation., Industrial melanism in peppered moth, Biston, betularia, is an example of transient polymorphism., Upto 1848 peppered moths found in and around, Manchester were creamy white with black dots, and darkly shaded areas. These were called, nonmelanic forms. In 1848, a single black coloured, moth appeared among nonmelanic forms., The black or melanic form arose by a recurring, random mutation. The nonmelanic forms were, able to successfully camouflage with the lichens, while resting and were able to survive, while the, melanic forms were easily spotted out and preyed, upon and were eliminated. As a result of rapid, industrialization in Great Britain, large amount of, soot and other gases were poured into the, atmosphere. These were deposited in the, environment making it sooty and dark and, destroying the lichens., Thus polymorphism in peppered moth was only, for a short period and favoured strong selection., The transient polymorphism is seen during, directional selection, where one form or character, is gradually being replaced by another.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 234, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 27, , Human Evolution, l, l, , l, , l, l, l, , l, , l, , l, , l, l, , Human evolution states that humans developed, from primates or ape like ancestors., Charles Darwin published his idea about man’s, ancestory in the book ‘Descent of man and, selection in Relation to sex’. He suggested that, man, apes and monkeys have a common ancestor., Anthropology is the study of human evolution and, culture. It deals with fossils of prehistoric and living, man., Genelogy is the sequential arrangement of stages, in evolution., The field of science which studies the human fossil, record is known as palaeoanthropology., It is the intersection of the disciplines of, palaeontology (the study of ancient life forms), and anthropology (the study of humans)., All human beings are classified as Homo sapiens, (Homo is the genus name meaning man, sapiens is, the species name meaning wise)., The fossils of prehuman and ancestral human, forms are obtained from widely diverse regions, of Africa, Asia and Europe which indicate that, man’s centre of origin was probably in Asia and, Africa., More precisely man has originated in central Asia,, because –, –, The oldest known fossils have been obtained, from Asia, China, Java and India (Shivalik, hills)., –, The number of domesticated animals and, plants is maximum in Asia., –, Climatic conditions in Asia and nearby places, were most conducive for human evolution., Prehuman evolution includes origin of mammals, and origin of primates., Mammals evolved in the jurassic period, about, , 195 million years ago from the cynodont reptiles, which branched off from the stem reptiles called, cotylosaurs., Cotylosaurs are the earliest and most primitive, of reptiles. They evolved from the amphibians, during the early carboniferous period some 340, million years ago, but were all extinct by the end, of the Triassic, about 90 million years later. From, among their members came 2 major evolutionary, lines – one led to the mammals & the other to the, archosaurs, ruling reptiles., l, l, , l, l, , l, , l, , l, , l, , The first mammals were shrew like terrestrial, insectivores or rat like creatures., The primates originated in the beginning of the, tertiary period (palaeocene epoch) about 65, million years ago from the small, terrestrial shrew, like insectibores, a stock from which other types of, existing mammals also arose., The primate (order of placental mammals) contains, two suborders : prosimians and anthropoids., The insectivore mammals namely, tree shrews, gave, rise to the primitive primates called prosimians in, the beginning of the tertiary period., Among living primates, the prosimians (suborder, Prosimii) (Gr.pro, before and simos, monkey, ape), include tarsiers, lemurs and lorises., Tarsiers are found in forests of Philippines and, East Indies. They are insectivorous mousesized, animals with enormous eyes suitable for, nocturnal life., Lemurs, squirrellike animals, are confined largely, to the island of Madagascar. They feed on plant, material, including fruits., Lorises occur in Africa and Asia including South, India.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 235, , ŘśŇďň– ◄ŢŐńśŚĽŐň–, Primates, Lemuroidea, Eg. Lemuroidea (Tree, shrews, Lemurs, AyeAye), Lorisiformes (Lorises), , ancestral to, , Tarsiodea, Eg. Tarsiers, , Earliest ancestor of man, (Prosimii), , Super families, , Hominoidea, , Ceboidea or, Platyrrhini, (New World monkeys), Eg. Spider monkey, , Apes, , Man, , Belong to single, family Pongidae, , Belong to single family, hominidae (Ramapithecus,, Kenyapithecus, Paranthropus,, Zinjanthropus,, Australopithecus, Homo), , Have four living genera, (i) Hyalobates—The Gibbon. It is the, smallest and most primitive of the apes., (ii) Simia (Pongo )— The Orangutan. It, builds nests on the trees., (iii) Pan—The Chimpanzee. It is the most, intelligent among the apes. Th e, chimpanzee can make and use tools., (iv) Gorilla—The Gorilla. It is the largest ape, and is very dangerous., , Anthropoidea, , (Monkey, apes, man), , Cercopithecoidea, or Catarrhini, (Old World monkeys), Eg. Rhesus monkey, , Includes a single genus, Homo,, which has a single living species,, sapiens and a single living sub, species, sapiens., , called simian evolution, Flow chart : Division of Primates., l, , l, , l, , l, , l, , l, , The anthropoids (suborder anthropoidea) (Gr., anthrop, man, and oid, like) are classified into three, superfamilies: new world monkeys (ceboidea), old, world monkeys (cercopithecoidea) and the, hominoids (hominoidea)., The tarsiers seem to have produced higher primates, termed simians (monkeys, apes, humans) in the, oligocene epoch through parapithecus., New world monkeys (platyrrhini) possess a flat, nose, long, sensitive and prehensile tail, non, opposable thumbs and clawed digits., New world monkeys are found in South America,, e.g., Alouatta (howler monkey) and Ateles (spider, monkey)., Old world monkeys (catarrhini) possess a narrow, nose, short and nonprehensile tail, opposable, thumbs and nailed digits., Old world monkeys are found in Africa and Asia,, , l, l, , l, , l, , l, l, l, , e.g., Papio (baboon), Macaca mulatta (rhesus, monkey), Presbytis (langur), etc., Hominoids includes apes and the hominids, (humans and direct ancestors)., Four types of apes have survived until today; the, gibbon and the orangutan are found in Asia, the, gorilla and the chimpanzee inhabit Africa., The Gibbon (prmitive ape) is the smallest of the, apes (5.5–11 kg) and the Gorilla (developed ape),, the largest of the apes (180 kg)., Brachiation is a way of travelling through trees by, means of swinging and hanging from links and, branches. Gibbon implements this technique., The closest relative of modern man is considered, to be chimpanzee., Simian shelf is a character of apes, it connects the, anterior part of the mandibles., Mammals, the class to which humans belong,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 236, , l, , l, l, l, l, , l, l, , l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , evolved 210 240 million years back from, cynodont/ synapsid reptiles., The term anthropoid apes is used for ancestral, anthropoids from which monkeys ® apes ®, human evolved., Apes are characterised by absence of tail., Human are placed in the family hominidae., The evolutionary line of old world monkeys, diverged from parapithecus in the oligocene., Evolution of man from ape like ancestors is, supported by molecular and anatomical, evidences besides the fossil evidence., In modern classification, humans have been, placed in class mammalia and order primates., Some anthropologists divide human beings into, six races, viz. caucasoids, negroids, mongoloids,, Australian natives, American Indians, and, Polynesians., All human races have the same chromosome, number and gross morphology., The diploid number of chromosomes in gorilla,, chimpanzee and orangutan is 48., Homo is the genus which is divided into the, following species : habilis, and sapiens. It is the, genus to which humans belong., Common origin of man and chimpanzee is best, shown by chromosome number and banding, pattern. Chimpanzees are the most human like of the, apes and frequently used in psychological experiments., Evidences for common ancestory of great apes &, man are :–, –, Chromosomal evidence – Somatic cells of, man have 46 (23 pairs) chromosomes. In apes, their number is 48. Man has evolved from an, ancestor having 48 chromosomes by the, centromeric fusion of two chromosomes., Chromosomes of man and apes have been, studied with special staining techniques and, it has been established that –, (a) chromosomes of man and apes have, similar banding pattern., (b) some chromosome of man and apes have, identical bands., (c) the banding pattern of human, chromosome number 3 and 6 are, compared with those of particular, autosomes in the chimpanzee. It shows a, common origin for man and chimpanzee., , Evidence from blood proteins – It has been, proved by the blood protein tests that man is, most closely related to great apes (Chimpanzee, and Gorilla) and next closest, in order, are the, old world monkeys, the new world monkeys, and tarsiers., –, Evidence from blood groups – In humans, four blood groups A, B, AB and O occur. The, blood groups A and B are found in apes but, not in monkeys. This indicates that human, beings are more closely related to apes than, to monkeys., –, Evidence from haemoglobin – There is 99%, homology in haemoglobin of man and gorilla., This suggests that the two are closely related., Characteristics of primates are –, –, Arboreal (tree dwelling) habit., –, Opposable great toe and thumb for grasping., –, Eyes in front of head for stereoscopic vision, (depth perception), –, Expanded forebrain., –, Lengthy gestation, one birth at a time., , –, , l, , EVOLUTION OF MAN, l, l, l, , l, , l, , l, , Evolution of man probably took place in central, Africa., Carolus linnaeus gave the scientific name Homo, sapiens to man., Erect posture, perfect bipedal locomotion,, orthognathus (flat) face, grasping hands, upright, neck are the characteristic of modern man., In modern man, cranial capacity is high,, 1300 1600 cc with brain to body weight ratio, being highest 1:46., Dryopithecus is common ancestor of human and, apes that lived in arboreal life in Asia as well as, Africa., Origin and evolution of man were explained under, the following headings – prior to ape man; ape, man including prehistoric man; and true man, including the living modern man., , Prior to Ape men, l, Parapithecus – It was discovered from the, oligocene epoch in Egypt. This fossil is believed, to represent the ancestors of today’s old world, monkeys, apes and humans., l, Propliopithecus – This fossil was discovered from, miocene strata of Faiyum depression.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ◄ŢŐńśŚĽŐň–, l, , l, , l, , l, , l, , l, l, , l, , Limnopithecus and Pliopithecus – These fossil apes, represent altogether a different line of evolution, which diverged from the hominid line quite early, and become extinct during pliocene., Dryopithecus – Fossil of Dryopithecus africanus, was discovered from miocene rocks of Africa, and Europe. It lived about 20 25 million years, ago. Dryopithecus africanus is regarded as, common ancestor of man and apes., Proconsul – Proconsul africanus was discovered, by S.B. Leaky (1948) from the rocks around lake, Victoria of Kenya, Africa. It lived in early miocene, epoch., Shivapithecus – This fossil was discovered from, middle and late pliocene rocks of Shivalik hills, of India, hence it is named Shivapithecus., Ramapithecus – It has been established that in late, miocene epoch Dryopithecus gave rise to, Ramapithecus which was on the direct line of, human evolution. Ramapithecus survived from late, miocene to pliocene. Thus he appeared about 14 15, million year ago., Fossil of Ramapithecus was discovered by Edward, Lewis from pliocene rocks of Shivalik hills of India., Similar to Ramapithecus, Kenyapithecus wickeri, was discovered from pliocene rocks of Kenya, (Africa)., There is a gap of about 9 10 million years in, Ramapithecus and Australopithecus., , Ape man including prehistoric men, l, Australopithecus (first ape man) – The early human, stock gave rise to Australopithecus., –, Commonly, called, southern, ape,, Austratopithecus appeared about 4 to 1.5, million years ago (early pleistocene)., –, Tuang baby (A.africanus) was discovered by, Raymond Dart from Africa., –, Lucy (A. afarensis) excaveted by Donald, Johanson., –, He had both human and ape characters with, bipedal locomotion, omnivorous diet and, erect posture (ancestor of man who first stood, erect)., –, His cranial capacity was 350 480 c.c., –, Six species of Australopithecus known as, A.ramidus, A. afarensis (Lucy), A. africanus, (Tuang baby), A.aethiopicus, A. robustus and, A. boisei., , l, , l, , 237, , Homo habilis (first homonid tool maker or, Handy man)., –, Homo habilis [Homo (man) habilis (skillful, or mentally able)] lived in early pleistocene, about 2 1.75 million years ago., –, Nut cracker fossil man, discovered by Leakey., –, His cranial capacity was about 735 c.c., –, He was the first fossil man who used tools, of chipped stones extensively., Homo erectus (erect man), –, H. erectus is considered a direct ancestor of, modern man., –, Homo erectus evolved from Homo habilis, a bout 1 .7 million years a go in th e, pleistocene., –, Homo erectus includes three fossils – java, ape man, peking man, and heidelberg man., –, Java Ape man’s (Homo erectus =, Pithecanthropus erectus) fossils (discovered, by E.Dubois from Java) occurred in the, pleistocene deposits some 1.5 million to, 5,00,000 years ago (middle pleistocene)., –, He had cranial capacity about 940 c.c., –, He was omnivorous, cannibal and had large, protruding jaws., –, He was the first prehistoric man to make, use of fire for hunting, defence and cooking., –, Peking man (Homo erectus pekinensis) =, Pithecanthropus pekinensis sinanthropus, pekinensis) lived most probably about 1.5 to, 5,00,000 years ago (middle pleistocene)., –, He had a cranial capacity about 850 1200 c.c., –, Peking man was slightly shorter, lighter and, weaker than Java man., –, Heidelberg man (Homo, erectus, heidelbergensis) had cranial capacity about, 1300 c.c. [(intermediate between those of erect, man (H.erectus) and neanderthal man (H., sapiens neanderthalensis)]., , True man including the living modern man, l, Neanderthal man (Homo sapiens neanderthalensis), –, Neanderthal man existed in the late, pleistocene period and its fossils were found, in the neanderthal valley in Germany., –, The cranial capacity was about 1450 c.c., roughly equal to that of modern man., –, He had slightly prognathous face and were, the lengendary cave dwellers.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 238, , ŕďőĽę– ĐĽŐńŐĹť, , Neanderthals were adapted to a cold, environment and were predatory and hunters., –, They used clothings, utensils and fine, tools., –, In neanderthal society injured and dead were, cared for, they even performed elaborate, burial rituals. Neanderthals may had a, religion., –, Became extinct 35, 000 years ago., Cromagnon man (Homo sapiens fossil), –, Cromagnon man emerged about 34000, years ago in holocene epoch. Thus it is, regarded as most recent ancestor of today’s, man., –, It’s fossils were first discovered in 1868 from, Cromagnon rocks of France by Mac, Gregor., –, These succeeded neanderthals and became, extinct about 20, 000 years ago., –, They were much more advanced than the, neanderthals and belonged to Homo sapiens., –, Cromagnon has perfectly orthognathous face., –, The cranial capacity was about 1650 c.c. (thus, believed cromagnon man was somewhat more, intelligent and cultured than the man of today)., –, Cromagnon man first started cave painting, as well as hunting with domesticated dogs., –, They were omnivorous and expressed, themselves through painting and sculpture, (cave paintings)., Modern man (Homo sapiens sapiens) – First, appeared about 10,000 years ago in Asia near, Caspian sea. Have cranial capacity of 1300 1600, c.c. They have developed sound into words., Characteristic features of man are –, –, Large brain and cranial cavity., –, Foramen magnum below the brain box., –, Bipedal locomotion and release of forelimbs, for other purposes., –, Erect posture and free hands., –, Opposable thumbs and grasping hands., –, Sensitivity., –, Reduced fertility., –, Social organization., –, Development of speech., –, Ability to learn and transmit experiences., –, Binocular and stereoscopic vision., –, Weak brow ridges and shortening of jaws., –, , l, , l, , l, , Dryopithecus africanus, [earliest fossil ape/proconsul], Ramapithecus, [earliest hominid fossil], Australopithecus afarensis, [the African ape man with cranial capacity 450 cc], Australopithecus africanus, [tuang baby with cranial capacity 350 450 cc], Homo habilis, [the stone tool maker with cranial capacity 735 cc], H. erectus, [the erect man with cranial capacity 800 1100 cc], H. erectus erectus / Pithecanthropus erectus, [Java man with cranial capacity 800 1000 cc], H. erectus pekinensis, [peking man with cranial capacity 850 1200 cc], Homo neanderthalensis, [neanderthal man with cranial capacity, 1450 cc], Homo sapiens fossilis, [cromagnon man with capacity 1650 cc], Homo sapiens sapiens, [the living modern man with cranial capacity, 1300 1600 cc], , Table : Cranial capacities of apes and man., Primates, , Cranial capacities, (in cubic centimetres), Chimpanzee and Gorilla, 325510 c.c., Australopithecus, 350450 c.c., Homo habilis, 735 c.c., Java ape man, 940 c.c., Peking man, 8501200 c.c., Heidelberg man, 1300 c.c., Neanderthal man, 1450 c.c., Cromagnon man, 1650 c.c., Living modern man, 13001600 c.c., l, l, l, , The continent where maximum fossils of, prehistoric man have been found is Africa., Cradle of human evolution is South Africa., Piltdown man is hypothetical, developed on the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 239, , ŘśŇďň– ◄ŢŐńśŚĽŐň, , l, , l, , l, l, , l, , l, l, l, l, , basis of artefact / hoax consisting of fragments of, skull at Piltdown, England., Heidelberg man, Sola man, Rhodesian man and, Altarutic man are believed to be variants of Homo, erectus., The entire period through which man has improved, the techniques of constructing instruments has been, divided into palaeolithic, mesolithic and neolithic, ages., Paleolithic age represents age of tools of stones, and bones, cave painting in later period., Mesolithic age represents as the age of animal, husbandary, development of language, reading, and writing., Neolithic age represents development of, agriculture, manufacture of pottery and clothes, etc., Neolithic has continued with bronze age and then, iron age., Evolutionary explosion of mammals occurred in, palaeocene period., First man like apes appeared in miocene., In pleistocene, extinction of many large mammals, occurred and also referred to as age of man., , Table : Taxonomic position of modern humans, Kingdom, , – Animalia, , Phylum, , – Chordata, , Sub phylum – Vertebrata, Craniata, Section, Superclass, Class, , – Gnathostomata, – Tetrapoda, – Mammalia, , Infra class, Order, , – Eutheria, – Primates, , Suborder, , – Anthropoidea, , Family, , – Hominidae, , Genus, Species, Subspecies, , – Homo, – sapiens, – sapiens, , Intake of complex, food, defaecation., Notochord, dorsal, hollow C.N.S., Vertebral column, Cranium (brain, box), Jaws, Four limbs, Mammary glands,, hair, pinna, True placenta, Nails over the, digits, Facial muscles for, e m o t i on a l, expression, Erect posture,, b i p e d a l, locomotion, Man, Wise
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 240, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 28, , Plant Taxonomy, l, l, l, , l, , l, , l, , Taxonomy is the branch of botany which deals with, identification, nomenclature and classification of plants., Taxonomy is also called systemic botany., The study of taxonomy has among its main, objectives the learning of the kind of plants on, earth and their names, of their distinctions, of their, affinities, their distribution & characteristics and, habitats, and the correlation of these facts of, knowledge with pertinent scientific data., A secondary objective taxonomy is the assemblage, of knowledge gained. Floras are published to, account for the plant of a given area., They are essential to any study of the natural, resources of an area, to studies of land potentials,, to evaluation of resources of raw materials possible, suited to man’s needs., A third important and scientific objective is the, demonstration of the tremendrous diversity of the plants, & their relation to man’s understanding of evolution., , –, –, –, –, –, –, , l, , TAXONOMIC DESCRIPTION OF, FLOWERING/ANGIOSPERMIC PLANT, l, , l, l, l, l, , l, , Description of a flowering/angiospermic plant in, semitechnical language is done using various, morphological features., Habit – Herb, shrub, tree, twinner, trailer, creeper, or climber., Habitat – Xerophyte, mesophyte, hydrophyte,, halophyte or epiphyte., Life span – Annual, biennial or perennial., Root, –, Tap root or adventitious root., –, Branched/unbranched., –, Modification if any fleshy/fibrous aerial/, nodulated/tuberous etc., Stem, –, Texture of stem Herbaceous/woody., –, Aerial / underground., , l, , Habit of stem Erect / prostrate / creeping /, twinning / climbing., Branching Branched / unbranched, kind of, branching., Shape Cylindrical / angular / flattened /, square / ribbed / jointed., Solid / fistular., Surface Glabrous / hairy / spring / prickly., Modifications if any Rhizome / bulb / tubers /, corm / phylloclade / runner / stolon / offset /, suckers, etc., Colour Green / grey / any other., Any other special feature., , –, –, Leaf, –, Insertion Radicle / cauline / ramel., –, Type Simple / compound (palmately or, pinnately compound)., –, Stipulate / exstipulate, nature of stipule Free, lateral / scaly / adnate / inter petiolar / intra, petiolar / ochreate / foliaceous / spinous /, tendrillar / convolute., –, Petiolate / sessile / sub Sessile., –, Nature of leaf base., –, Phyllotaxy Alternate / opposite (decussate, or superposed) / whorled., –, Shape of leaf, leaf margin, leaf apex., –, Venation Reticulate / parallel, unicostate /, multicostate (Convergent or divergent type)., –, Texture Coriaceaceous / membranous /, scarious / fleshy / succulent)., –, Modifications, if any., –, Colour Green, variegated., Inflorescence, –, Racemose / cymose / mixed / special., –, If racemose Typical raceme / spike /, compound spike / spikelet / catkin / spadix /, corymb/ umbel / capitulum.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, , 245, , Chapter 29, , Morphology of Flowering, Plants, l, , l, l, , l, l, l, , l, , l, , Morphology (Greek morphe from, logos, Science), is the branch of biology which deals with the study, of form, structure and relative position of different, organs., Morphology is of two types external and, internal., External morphology is the study of external form, like shape, size and colour, structure and relative, position of different organs., Internal morphology studies the internal form and, structure of organisms., Internal morphology has two parts: anatomy and, histology., Anatomy (Greek ana again, tommein to cut) is, a branch of biology that deals with the study of, internal structure which is exposed after dissection, and opening of various parts., Histology (Greek histos wole, logos Science), is the study of tissues, their composition and, structure as observed with the help of microscope., Importance of morphology are as follows –, –, Gives a particular contour to the body of an, organism., –, Organisms are recognised by their external, morphology., –, Classification is based on the morphological, traits of the organisms., –, It gives information as to homology and, analogy of organs., –, With the help of external and internal, morphology, structural simplicity and, complexity can be known., –, All breeding experiments are based on, morphological data. It includes plants, productivity., , –, –, , l, , l, , l, , l, l, , l, , l, , l, l, , It indicates the structural adaptations to habitat., Difference between juvenile and mature, phases are indicated by external morphology., Flowering plants or angiosperms are seeds bearing, plants (spermatophytes, phanerogams) in which, their seeds are always enclosed in a definite organ, called the ovary inside the fruits, and the, sporophylls are organised into flowers., The angiosperms are found in most diverse, conditions and dominate the earth’s vegetation, today. They provide us food, clothing, timber,, spices, beverages, rubber, medicines and fuel., There are about 3, 00, 000 species of flowering, plants which have diverse habits, habitats, modes, of nutrition, life span, shape and size., Angiosperms are divided into two groups – dicots, and monocots., The dicotyledons, have leaves with a network of, veins, vascular bundles in the stem in a circle, root, with a definite number of vascular bundles and floral, parts in multiples of five (sometimes four)., The monocotyledons have vascular bundles in the, stem, roots with several strands of vascular tissues, and floral parts in multiples of three., Angiosperms are found in almost all places. The, plants that grow on soil are called terrestrial plants., The plants found in water are hydrophytes and, those growing in extremely dry habitats are, specialised to grow in conditions intermediate, between dry wet and very dry conditions, they are, called as mesophytes., The flowering plants primarily consists of an axis,, root system and shoot system., Shoot system lies above the ground and the root, system lies below.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 246, , ŕďőĽę– ĐĽŐńŐĹť, Plant, , l, , Root system, Tap, root, , Lateral Vegetative, root, shoot, Main, stem, , l, l, l, , Shoot system, , Lateral, stem, , Reproductive, shoot, Inflorescence, Flower, , Shoot system bears branches, leaves, flowers and, fruits., The root, leaves and branches constitute the, vegetative parts of the plants., The flowers, fruits and seeds form the, reproductive parts of the plants., , ROOT, l, l, , l, l, , l, l, l, l, l, l, l, l, , l, , l, , Root is an important vegetative part of the plant, mainly responsible for nutrition and support., Root is the descending, nongreen, underground, part, lacking nodes, internodes, leaves and buds., (Except sdventitious buds in Ipomea batatus which, takes part in vegetative propagation)., Root is positively geotropic, positively, hydrotropic and negatively phototropic., Root consists of 4 major zones root cap,, meristematic zone, zone of cell elongation and, maturation zone., The cap like structure made up of thin walled cells, that covers the root apex is the root cap., The root cap made of dead cells, protects the, young growing cells of the apical region., Mucilage secreted by the cells of the root cap help, in easy penetration of root into soil., Root cap is also known as calyptra as it originates, from the calyptrogen., Root caps are absent in hydrophytes, epiphytes,, parasites (haustoria) and mycorrhizae., Multiple root cap is present in Pandanus (screw, pine)., In hydrophytes root pockets are present instead, of root cap, eg. Pistia, Lemna., Root cap and root pocket are structurally similar but, root pockets once damaged are not regenerated, whereas root caps are regenerated., Meristematic zone is present just above the root, cap., , l, , l, , l, , l, , l, l, , l, l, , Meristematic zone is made up of compactly, arranged small, thin walled isodiametric and, meristematic cells having dense protoplasm and, large nucleus., The meristematic initial cells of this region, produce two types of cells one formed towards, apex develops into calyptrogen & the second, formed towards base develops into histogen., The cells of meristematic region are in active state, of divisions and so this is the main growing region, of the root., The region of cell elongation is present above the, meristematic zone resulting in increase in the length, of the root., The external cells of this region possess the power, of absorption of water and mineral salts from the, soil., Above the cell elongation zone, is present the cell, maturation zone. Secondary growth takes place in, this region., Region of maturation is the area of origin of lateral, root., Unicellular and ephemeral root hairs are formed, from the epidermal cells in this zone (maturation, zone). Root hair region is called piliferous zone., The root hairs help in absorption of water., Root hairs are absent in all the plants where there, are no root caps., , Types of root system, l, l, l, l, , l, l, l, l, , l, , There are two types of root systems tap root and, fibrous roots (or adventitious roots)., The root that develops from radicle is tap root or, primary root., It forms lateral branches called secondary roots, which further divide to form tertiary roots., The tap root, with the secondary and tertiary roots, forms the tap root system. Rootlets are the ultimate, root branches that bear root hair., Tap root system is the characteristic of dicot plants., Tap root system is of two types deep feeder and, surface feeder., Deep feeder tap root system has elongated tap root, which penetrates the deeper layers of soil., In surface feeder tap root system, the root does, not elongate much but the secondary roots spread, to a greater horizontal area., Roots developing from any part of the plant other, than the radicle is called adventitious roots.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, , l, l, , l, , In underground adventitious root system, the primary, root is short lived and is replaced by a number of, fine fibrous adventitious roots, developing from the, base of the stem., Adventitious roots are mainly found in monocots., Adventitious roots can be grouped into 3 types on, the basis of their appearance –, –, Roots arising from the base of the stem, eg., Triticum., –, Roots arising from leaves, eg. Bryophyllum., –, Roots developing from nodes and internodes, of the stem., In addition to the normal function of anchorage,, absorption of water and minerals, roots perform, some special function for which they get modified., , Modification of roots, , Modifications of roots systems, l, Modification is a change from the normal structure, of a plant organ to perform new or additional, function according to the environment., , l, , l, , l, , l, , l, , Modification of tap root, Fleshy Nodulated, Conical, , Fusiform, , Pneumatophores Root buttress, Napiform, , l, , Tuberous, , Modification of adventitious root, Fleshy, Mechanical, Moniliform support, Prop root, Annulated, Stilt root, Tuberous, Climbing, Fasciculated, roots, Palmate, Nodulose, , l, , l, , Vital function, Parasitic roots, Assimilatory roots, Mycorrhizal roots, Epiphytic roots, Contractile roots, Floating roots, Reproductive roots, Root thorns, , Tap root are modified into – fleshy, nodulated,, pneumatophores and root buttress., When the root becomes swollen and fleshy for, storage, they are called fleshy roots. Fleshy root may, be , –, Conical : swollen at the base and narrow at, the apex, eg. Daucus carota (carrot)., –, Fusiform : thicker in the middle and tapers, at both ends for storage of food, eg. Raphanus, sativus (radish)., –, Napiform : very thick upper portion and tapers, in the lower end, eg. Brassica napas., –, Tuberous : the roots get swollen at any portion, , l, , 247, , and do not assume any definite shape, eg., Mirabilis jalapa., Nodulated : In leguminous plant, tubercles or, nodules are formed on the secondary and tertiary, branches of roots, where nitrogen fixing bacteria, are present, Eg. Glycine max., Respiratory roots or pneumatophores are erect, root showing negatively geotropic, usually club, shaped & protrudes some distance above, substratum. They have minute pores called, pneumathodes for intake of oxygen, eg., Rhizophora., Such roots are common in many mangrove species, growing in water logged areas where soil aeration, is extremely poor., Root buttress : Horizontal roots arise jointly from, the bases of the tap root and the trunk. They provide, extra support, eg. rubber tree., Adventitious roots can be modified on the basis, of their function like, fleshy for food storage,, mechanical support and for vital functions., Fleshy adventitious roots are of following types–, –, Moniliform (or beaded) : Roots are swollen, at regular intervals and have bead like, appearance, eg. Momordica., –, Annulated : Roots possess a series of ring, like outgrowths or swellings, eg. Cephalis., –, Tuberous : The swollen root do not assume, any definite shape, eg. Ipomea batatas., –, Fasciculated : The swollen roots occur in, clusters from lower nodes of stems, eg., Asparagus (monocot root), Dahlia., –, Palmate roots : Fleshy roots are thickened, like palm of human hand, eg. Orchis., –, Nodulose : The apex or tip of the roots become, swollen, eg. Curcuma amada., Some adventitious roots modify to provide, mechanical support like prop root, stilt root &, climber root., –, Prop roots : Arise from branches of plants, and enter the soil, to provide support in huge, trees, eg. Ficus benghalensis (banyan)., –, Stilt roots : Aerial, obliquely growing roots, formed from the nodes of lower most portion, of the stem and fix firmly to the soil, eg. Zea, mays (maize)., –, Climbing root or clinging roots : Formed, from nodes of stem, eg. Piper betel (pan).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 248, , l, , l, , l, , l, , Some adventitious roots are modified to perform, several vital functions like parasitic, assimilatory,, mycorrhizal, epiphytic etc., Parasitic roots : Parasitic plants develop sucking, roots or haustoria which enters the host plant for, drawing nutritions, eg. Cuscuta., The plants which depend totally on host for food, and water are called complete parasite. The, haustoria of these plants have connections with both, xylem and phloem of host., Plants which depend on hosts only for mineral, and water are called partial parasite. These are, chlorophyllous. Haustoria of these plants have only, connection with xylem only., Partial stem parasite, Partial root parasite, Total stem parasite, Total root parasite, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , –, –, –, –, , Viscum loranthus, Santatum album, Cuscuta, Orobanche, , Assimilatory roots : Green roots capable of, photosynthesis, due to presence of chlorophyll, eg., Tinospora., Mycorrhizal roots bear fungal hyphae which, function as root hair, eg. Pinus., Epiphytic roots have aerial roots which may be of, 3 types – clinging for fixation, absorbing (for, absorption of mineral salts and moisture) and, hygroscopic aerial., The aerial roots do not have root caps and root, hair. They have a covering of dead spongy tissue, known as velamen, eg. Vanda., Contractile roots : The apical portion of some thick, roots of the underground stem contract and help the, plant in fixation, eg. Corm of Crocus., Floating roots : In Jussiaea a number of, adventitious roots arise from each node. Some of, these roots became inflated, filled with air, come, out of water and helps the plant in floatation., Floating roots also help in gaseous exchange. In, floating plants of Salvinia one leaf of each node is, modified into roots for balancing., Reproductive roots develop adventitious buds, that, grow into new plant under favourable conditions,, eg. sweet potato., The root that becomes stout and pointed and arises, from stem are called thorny roots, eg. Acanthorhiza., Thorny roots give protection to the plant., Leaf root : In some adventitious roots are produced, on margin of leaves, eg. Bryophyllum., , l, , The modified, aerial adventitious roots branched, profusely to form a nest like structure that helps in the, absorption of mineral water from the leaf pitcher are, called nest roots, eg. Dischidia, Neottia (birds nests)., , Functions of roots, l, , l, , l, , The primary function of roots are –, (i) Anchorage (ii) Absorption of water and minerals,, (iii) Prevention of soil erosion, (iv) Transport., There are a numerous secondary or accessory, functions of roots like – storage, mechanical, support, nitrogen fixation, reproduction, floating,, photosynthesis, respiration etc., Many plants growing in aquatic habitat do not, possess roots (eg. Wolffia, Utricularia) and some, have roots only for balancing (eg. Lemna, Pistia)., , STEM, l, , l, l, l, l, l, , l, l, , l, , l, , l, , Stem is the aerial part of the plant that bears leaves, and flowers, have distinct nodes and internodes and, grows by means of terminal buds., Stem develops from the plumule., The stem branches are exogenous in origin., It is positively phototropic and negatively, geotropic., Stem along with its leaves and branches forms, the shoot system., A bud is a condensed immature or embryonic shoot, having a growing point surrounded by closely placed, immature leaves., Cabbage or Brassica oleracea var capitata is the, largest bud., According to their nature, buds are of three types :, vegetative (form only leafy shoot); floral, (reproductive buds that form flowers); and mixed, (forming both vegetative & floral branches)., According to their positions, buds are of two types, – terminal / apical (present at the apical end and, are meant for increasing the plant height) and, lateral (develop on stem or on branches at any side)., Lateral buds are of four different types – axillary, buds (developing in the axil of leaves); accessory, buds (occur on the lateral sides of axillary buds), extraaxillary buds (developing on the node by, outside the leaf base), and adventitious buds which, are of three different types foliar (on leaves),, radical (on roots), cauline (on stem)., Adventitious buds can be modified into thorns, (Citrus), bulbils (Allium cepa) or tendrils (Passiflora).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 249, , ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, l, l, l, , l, , l, , l, , l, l, l, , l, , l, l, , l, , l, , Unbranched stem is called caudex or columnar,, eg. palm, sugarcane, maize., Branched stem may be dichotomous or lateral in, nature., Lateral branching are of two types racemose, and cymose., The terminal bud continues to grow in racemose, type, and lateral branches are borne in acropetal, succession., In cymose branching the terminal bud stops, growing and gets modified into flower, tendril,, thorn etc., Cymose branching may be of three types , –, Monochasial, may be scorpioid (on both, sides) or helicoid (on one side)., –, Dichasial in which two lateral axillary buds, continue to grow, e.g. Carissa., –, Polychasial in which growth takes place by, whorl of axillary buds., Aerial stem may be classified broadly into three, types– upright (erect) stout stem, feeble weak, stem and reduced stem., Erect stems have sufficient mechanical strength to, support themselves, e.g., common stems types., Reduced stems are small flat disc like, without, distinguishable nodes and internodes., Reduced stem helps in floating in Lemna & Wolffia,, forms the base of bulb in onion and bears radical, leaves in carrot, turnip etc., Feeble weak stems are elongated, narrow and soft, stems which cannot support themselves in upright, position., Weak stem can be broadly classified into two major, types twiners and climbers., In twiners stem tip undergoes regular circular, movements for support, the phenomenon known as, circumnutation., Climbers are plants with weak and flexible stems, which possess clinging structures for clasping, support., Tendril climbers, – Passiflora (modified, axillary branches),, Lathyrus (whole leaf), Root climbers, – Tecoma, Piper, Scramblers, – Artabotrys, Lianes, – Tinospora, Adhesive disc climber – Ampelopsis, Trailers are plants with weak stem, which are fixed, , l, , to the soil at one point and branches spread along, the ground., On the nature of spreading of branches they are:, –, Procumbent when branches lie flat on, ground, e.g., Oxalis., –, Decumbent prostrate branches bends to rise, at apices, e.g. Tridax., –, Diffuse prostrate branches grow in all, direction, e.g. Euphorbia prostrata., , Modification of stem, l, , Modification of stem are of three types , underground, subaerial and aerial., Modifications of Stem, , Underground, Tuber, Rhizome, , Aerial, Subaerial, Stem tendril, Runner, Phylloclade, Stolon, , Bulb, , Thorns, , Sucker, , Corm, , Cladodes, Thalamus, , Offset, , Hooks, , Underground stem, Underground stems are nongreen stems that may, l, take part in perennations, store food, or help in, vegetative propagation., Why underground stems are not root ? Because,, Absence of root cap at the tip., Presence of terminal buds., Absence of root hairs near the apices., Presence of distinct nodes and internodes., Presence of scale leaves, axillary buds. ., Modified underground stem are of four types : stem, l, tuber, rhizome, corm and bulb., l, Stem tuber is the branch of main stem which, possesses axillary buds or eyes, and swells due to, food storage, e.g., Solanum tuberosum., Rhizome is fleshy stem with scaly leaves bearing, l, buds in their axil. Adventitious roots arise from, lower nodes, helps in perennation, e.g. Zingiber, officinale (ginger)., Rhizome rising obliquely in the soil, are called root, l, stalk, e.g., Alocasia., Corm is subspherical, swollen, growing vertically, l, in soil, adventitious roots at base of nodes, axillary, buds in axil of scale leaves, e.g. Colocasia,, Gladiolus., l, Bulb is highly reduced disc like stem with numerous
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 250, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , fleshy scaly leaves covering a central terminal bud,, adventitious buds arising from under surface., Tunicated bulbs are covered with dry membranous, sheaths called tunic, e.g. onion., In some the bulb consists of a number of bulblets, arranged in two or more concentric rings, e.g. Allium, sativum., Characteristic smell of onion is due to sulphur allyl, sulphide present in fleshy leaves., , Aerial stem, l, Aerial modification are of following types – stem, tendril, phylloclades, cladodes, thorn, thalamus, and hooks., Stem tendrils are fine, sensitive thread like wiry, l, structures which can coil around a support., On the basis of their origin stem tendril may be, l, of five different types , –, Axillary tendril tendrils at axil of leaves,, e.g. Passiflora., –, Extraaxillary from extraaxillary buds, found over the nodes, e.g., Cucurbita., –, Apical bud tendril develops opposite the, leaves from the apices of lower branches, e.g.,, Vitis vinifera., –, Tendrillar stem tip tip of stem branches get, modified into tendril, e.g., Gouniana., –, Floral bud tendrils terminal part of, inflorescence bears tendrils, e.g., Antigonon., Phylloclades are green, flat fleshy structure bearing, l, nodes and internodes, perform photosynthesis, instead of leaves. In some, the stem may store water,, e.g., Opuntia., l, Cladodes are green stem of limited growth,, generally one or two internodes long, that perform, the function of photosynthesis, e.g. Asparagus (one, internode long), Ruscus (2 internode long)., Stem gets modified to stiff, hard pointed structures, l, called thorns that perform defensive functions and, checks transpiration, e.g., Citrus, Duranta., l, Thorn may sometimes have leaves and flowers, (Aegele marmelos)., Thorns : modified stem with vascular cylinder, Spines : modified leaves with vascular strand, Prickles : superficial hard structures borne over, surface stem and leaves, vascular cylinder is absent., Bristles : modifications of hairs where deposition, of silica or calcium carbonate has occurred., , l, , l, l, l, l, , Thalamus is condensed stem axis which forms the, base of the flower, containing reduced nodes and, internodes, bearing sepals, petals, androecium and, gynoecium., Sometimes some of the internodes may elongate, between sepals and petals known as anthophore., Internodes between petals and stamens is called, androphore., Internode between stamens and carpels is called, gynophore., Pedicel or floral stalks of some plants produces a, curved hook to help the plant in climbing, e.g.,, Artabotrys., , Subaerial stem, Sub aerial stems are feeble and weak and aerial, l, part of them grows horizontally on the ground while, some parts remain underground and help in, vegetative propagation., Subaerial modification are of four types – runner,, l, stolon, sucker and offset., l, Runner is horizontal, green, devoid of leaves at, nodes, aerial branches arising from axil of scaly, leaves. Nodes bear adventitious roots and axillary, buds, e.g. Cynodon dactylon., Stolons are prostrate branches that originate from, l, the base of the crown and grow obliquely and the, tip, after coming in contact with the soil grows to, form a crown at the upper surface and adventitious, roots in the lower surface., l, Nodes bear scaly leaves with adventitious buds., Eg. Jasminum, Fragaria (straw berry)., l, S uc k e r is for m e d from th e nod e o f, underground stem and runs obliquely upward, inside the soil, comes out and forms new leafy, shoot, The lower portion of nodes give rise to, roots, e.g., Mentha., l, Offset is one internode long, short and thickened, special horizontal branches, that develop from below, a tuft or rosette of leaves, grows for some time and, bears a new tuft of leaves. Adventitious roots, develop from below the rosette, e.g. Pistia., , Functions of stem, l, l, , The stem performs both primary and secondary, functions., The stem conducts water and minerals from root, to leaves and other organs through xylem.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, l, l, , l, l, l, l, , l, , l, l, , l, l, , It conducts manufactured food from leaves to, other parts of plants through phloem., The stem bears the aerial structures like leaves,, flowers and fruits., The leaves are borne in such a way to provide, maximum sunlight and flowers are borne to expose, them to pollinating agent., Phylloclades and cladodes perform photosynthetic, functions., Various underground stem modifications are, specialised to store food., In sugarcane the aerial stem stores sugar in itself., Fleshy stems of Opuntia and other cacti store water, so that the plants can grow even when the soil, remains dry for months together., The stem bears thorns and prickles for protection, against browsing animals and loss of water in, transpiration., Curved thorns, hooks and tendrils formed from stem, structures help the plants in climbing., In Neptunia the stem bears a number of air cavities, which make the stem light and allow the plant to, float over the surface of water., All underground stems take part in perennation, during unfavourable season., Underground stems, runners, stolon and offsets can, take part in vegetative propagation of the plant., , l, , l, , l, , l, , l, , LEAF, l, l, , l, l, , l, l, , l, , Leaf (=phyllopodium) is the main photosynthetic, organ of the plant., Leaf is green, thin flattened outgrowth of the plant, arising from the node of the stem and having a, bud in its axil., Leaves always follow an acropetal order of, developmet and are exogenous in origin., A leaf is called dorsiventral if its dorsal surface, differs in structure from its ventral surface, eg. dicot, leaves., A leaf is called isobilateral when the two surfaces, are similar, eg. monocot leaves., A dorsiventral leaf is more strongly illuminated, on upper surface than on lower surface whereas, in isobilateral leaf there is equal illumination on, both sides of the leaf., Some cylindrical leaves have no distinction of the, two surfaces (unifacial) and are called centric, eg., onion., , l, , l, l, , l, , 251, , In peltate leaf, the leaf blade and the petiole usually, stand on one and the same plane, eg. lotus, water, lily., When leaves are directly borne by the aerial parts, of the stem and branches, it is called cauline, leaf., In pineapple, Agave etc. a cluster of leaves arises, from the short underground stem as if arouse from, roots, then it is called radical leaf., In grasses, a membranous tongue like outgrowth is, present at the junction of leaf base sheath and lamina, and it is called ligule., According to the origin and function of leaves they, may be grouped as–, –, Cotyledonary leaves or seed leaves : Are, embryonic seed leaves.They become distinct, in plant showing epigeal germination., –, Hypsophylls or bract leaves : Are leaves that, contain flower or an inflorescence in their axil., They perform the function of protection., –, Cataphylls or scale leaves : Are non green, present on aerial or underground parts, eg., rhizome, corm, phylloclade and cladode, bearing plants and perform the function of, protection., –, Sporophylls or fertile leaves : Are the leaves, which bear sporangia. These are mainly found, in gymnosperms and pteridophytes., –, Foliage leaves : Are the common leaves that, are green in colour and found on the main, stem and branches that perform the, function of photosynthesis., Occurrence of dissimilar foliage leaves on a plant, is called heterophylly. It is commonly seen in, emergent type of water plants, for eg. Limnophila, heterophylla, Trapa etc., Occurrence of dissimilar leaves on a node is called, anisophylly, eg., Boerhavia diffusa etc., In environmental heterophylly heterophyllous, leaves are produced in response to the surroundings, or environment in which a plant is living. This types, of heterophylly is found mostly in hydrophytes, like, Limnophila heterophylla, Ranunculus, aquatiolous., In developmental heterophylly plant produces, different kinds of leaves at different developmental, stages of its life. In Acacia malanoxylon the leaves
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 252, , l, , ŕďőĽę– ĐĽŐńŐĹť, , Parts of leaf, l, , stipules, (eg. cotton, Hibiscus rosa sinensis), (b), adnate stipules (eg. Rosa indica), (c) ochreate, stipules (eg. Rumex, Polygonum), (d) interpetiolar, stipules (eg. Ixora, Anthocephalus etc), (e), foliaceous stipules (eg. Lathyrus), (f) tendrillar, stipules (eg. Smilax), (g) bud scales (eg. banyan,, Artocarpus etc), (h) spiny stipules (eg. Mimosa,, Acacia, Zizyphus)., , of the young plant (seedling) are pinnately, bicompound. But in a mature plant, the leaf, consists of only expanded petiole (phyllode), without lamina., In habitual heterophylly, the plant produces, different types of leaves at every node throughout, its life, eg. Selaginella., A leaf consists of three parts i.e., leaf base, petiole, and lamina., , Leaf base, Leaf base (= hypopodium) is the basal part by, l, which leaf is attached to stem or branch., l, Different type of leaf bases are– pulvinus,, sheathing, decurrent, and amplexicaul., l, In pulvinus leaf base (for eg. in leguminosae plants,, mango, banyan) the leaf base is swollen., In sheathing leaf base (for eg. in monocots like, l, maize, sugarcane, banana) the leaf base expands, forming flat sheath which encloses the stem, portion above the node., l, In banana (Musa paradisiaca) leaf bases forms a, pseudostem or false stem while the actual stem is, below the ground., In decurrent leaf base (for eg. in Crotolaria,, l, Laggera etc.) the leaf base becomes flat broad, and winged covering the upper part of the, node., In amplexicaul leaf base (for eg. in Polygonum), l, the sheathing leaf base encloses the stem, completely., l, In many dicots, leaf base bears two lateral, outgrowths called stipules (which generally, protect the young leaves) and axillary buds., Small stipule like outgrowths called stipels are, l, found at the base of leaflets of a compound leaf., l, The leaves having stipules are termed as stipulate, while the leaves without stipules are called, exstipulate., l, The stipules are of three types according to the, time period of their attachment , –, Caducous, eg. Michelia champaca,, –, Deciduous, eg. Cassia, Dilenia etc;, –, Persistent, eg. rose, Hibiscus rosa sinensis., l, According to the structure and location, stipules, may be of following types– (a) free lateral, , Petiole, Petiole (= Mesopodium) is the stalk of the leaf, that, l, connects the lamina with the stem and is generally, cylindrical, being terete or grooved., l, When petiole is present, the leaf is said to be, petiolate or stalked and when it is absent, the leaf, is said to be sessile., l, Petioles show certain pecularities which are of, different types namely winged petiole, tendrillar, petiole, phyllode and floating petiole., In winged petiole, the petiole is modified into, l, flattened, winged leaf like structure. For eg., in, C itru s (ora nge, pummelo, lemon etc),, Feronia etc., l, In tendrillar petiole, petiole is tendrillar in nature, and helps the plant to climb up, eg. in Clematis,, Nepenthes., In some plants like Australian acacia (Acacia, l, auriculaeformis), Parkinsonia etc. the petiole, performs the function of leaf by modifying into leaf, like structure called phyllode., l, In floating or bulbous petioles, the petiole become, spongy bulb (pseudobulb) which contains many air, cavities and thus help the plant in floating, for eg., Eichhornia, Trapa., Lamina, l, Lamina (= epipodium) or leaf blade is green and, expanded portion of the leaf. (For division of lamina, refer flow chart on page no. 253), In the middle of the lamina, a strong vein called, l, midrib is present which extends from its base to, the apex., l, The midrib produces thinner lateral veins, which, in turn, give rise to still thinner veins or veinlets, and as a result a net like structure is visible in the, lamina., , Venation, Vernation and Ptyxis, l, , Distribution of veins (vascular bundles) and the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 254, , l, , l, , l, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , In unicostate parallel venation only one midrib is, present which gives out lateral veins running parallel, to each other, either towards the apex or margins,, eg. Canna, banana etc., In multicostate parallel venation, many midribs, are formed from the petiole. It is of two types , convergent type and divergent type., In convergent type different midribs running, parallel to each other converge at the apex, eg., wheat, bamboo, grasses etc., In divergent type a number of midribs extend, towards the margins, eg. palms etc., The function of venation is conduction of food, material, distribution of mineral, water and to, provide shape and mechanical strength to the, lamina., The arrangement of leaves in relation to each, other in the bud is called vernation., The way in which young leaves are folded or rolled, in the bud is called ptyxis., , l, l, l, , l, , l, , l, , Phyllotaxy, l, l, , l, l, , l, l, , l, l, , Phyllotaxy means the arrangement of leaves on, both main stem and branches., Arrangement of phyllotaxy is made to facilitate the, leaves to obtain maximum light for, photosynthesis., The three types of phyllotaxy are alternate,, opposite and whorled arrangement., In alternate (or spiral) form of arrangement, one, leaf is borne at a node and leaves are arranged, alternately giving a spiral form, eg., mango, mustard,, tobacco etc., In opposite arrangement each node gives rise to, two leaves, arranged opposite to each other., Opposite phyllotaxy are of two types – opposite, superposed (each pair parallel to the next pair, eg.,, Ixora etc); and opposite decussate (one pair of right, angle to the next pair, eg., Ocimum etc)., In whorled arrangement more than two leaves are, formed from each node, eg. Nerium, Alstonia etc., Both alternate phyllotaxy (in vegetative parts) and, opposite phyllotaxy (at the floral region) are found, in Datura., , Simple and compound leaves, l, , Simple leaf is a leaf having a single blade which may, be entire or incised, eg. mango, guava, papaya etc., , l, , l, , l, , l, , l, , In pinnate simple leaf the incisions are pointed, towards the midrib, eg. radish., In palmate simple leaf the incisions are pointed, towards the petiole, eg. Ricinus., In compound leaf, the incision of the leaf blade, goes down to the midrib (rachis) or to the petiole, so the leaf is broken up into a number of segments, called leaflets. It is of two types pinnately, compound leaf and palmately compound leaf., In pinnate compound leaf the rachis is the original, midrib and the leaflets are arranged along its two, sides as a feather. It is of four types (a) unipinnate,, (b) bipinnate, (c) tripinnate, and (d) decompound., In unipinnate type, leaflets are directly associated, with the rachis. It is of two types paripinnate, (rachis terminated by even number of leaflets) eg., tamarind, asoka etc. and imparipinnate (rachis, terminated by an odd number of leaflets), eg. rose,, Clitoria etc., In bipinnate type, rachis is subdivided i.e., the, secondary leaflets are formed on both sides of the, primary leaflets, eg. Mimosa pudica, Acacia etc., In tripinnate compound leaf the rachis divides to, form primary leaflets which give rise to secondary, leaflets which inturn form tertiary leaflets, i.e.,, divides thrice, eg. Moringa etc., In decompound type, the division of rachis, occurs more than three times, eg. corriander,, carrot etc., In palmately compound leaf the incisions of lamina, are pointed towards the base and are connected to, the petiole tip., Types of palmately compound leaf are –, –, Unifoliate (single leaflet), eg. Citrus., –, Bifoliate (two leaflets) are attached at the tip, of petiole), eg. Balanites, Bignonia., –, Trifoliate (three leaflets), eg. Oxalis., –, Quadrifoliate (four leaflets), eg. Paris, quadrifolia, in pteridophytes Marsilia., –, Multifoliate (more than four leaflets), eg., Cleome, Bombax etc., Leaves perform various functions beside, photosynthesis and thus they are modified into, different forms like, (a) leaf tendrils (help in climbing), eg. sweet pea,, (b) leaf spines (protection of plants, reduce, transpiration), eg., Argemone, Acacia,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , (c) leaf hooks (help in climbing), eg. Bignonia,, (d) scale or protective leaf, eg. Ficus, Artocarpus., etc.,, (e) leaf roots (a leaf transformed into roots for, balancing on water), eg., Salvinia,, (f) leaf bladders (part of leaf segment is modified, into bladder), eg., Utricularia,, (g) leaf pitchers (leaf is modified into pitcher),, eg., Nepenthes (insectivorous), Dischidia, (noninsectivorous),, (h) leaf tentacles, eg., Drosera,, (i) phyllode (petioles modify into leaf like, structure), eg. Parkinsonia, Acacia, auriculiformis., Parts of leaf modified into spines, –, Stipules eg. Zizyphus, –, Leaf margins eg. Argemone, –, Leaf apex eg. Yucca, –, Entire leaf eg. Barberis., Parts of leaf modified into tendril, –, Stipules eg., Smilax, –, Petiole eg., Clematis, –, Leaf apex eg., Gloriosa, –, Leaflets eg., Pisum., –, Whole leaf Lathyrus, , INFLORESCENCE, l, l, l, l, l, l, l, l, , l, , Table : Exceptions is leaf morphology, Character, , 255, , The arrangement of flowers on the floral axis, (peduncle) is known as inflorescence., Cauliflory is the development of flowers on old, stems, eg Artocarpus., The main axis of the inflorescence together with, the lateral axes, if present, is known as peduncle., The floral axis may be simple (i.e. unbranched) or, compound (i.e. branched)., In unbranched condition the flowers are borne on, the simple axis called rachis., In branched axis the flowers are borne only on the, branches which are called rachises., The flowers that arise singly at the axil of vegetative, leaf are solitary flower, eg., china rose, Datura., Inflorescence may be of following types –, –, Terminal Single flower present on floral, axis., –, Axillary infloresence When flower is found, in the axil of a leaf., –, Intercalary Single flower present in between, the floral axis., Axillary inflorescence are of the following types –, –, Racemose or indefinite inflorescence, –, Cymose or definite inflorescence, –, Mixed inflorescence, –, Special type of inflorescence, , Racemose inflorescence, , Examples, , 1. Monocots with reticulate, , Smilax, Alocasia., , Dioscorea,, , l, , 2. Dicots with parallel, venation, , Eryngium, Calophyllum, inophyllum., , l, , 3. Dichotomous venation, , Gingko biloba, , 4. Dicots with xerophytic, leaves show isobilateral, symmetry, , Eucalyptus, , 5. Reproductive leaves, , Bryophyllum, , 6. Epiphyllous buds occur, in the notches of leaf, margins, , Bryophyllum, , 7. Root like structures to, absorb mineral water, , Utricularia and, Limnophila, , 8. Terrestrial plant with, longest leaves, , Rapbia teedigera, , 9. Largest leaves, , Victoria regia, , l, l, , l, , l, , l, , In racemose type main axis of inflorescence with, indefinite (indeterminate) growth gives rise to, (lateral or axillary) flowers in an acropetal order., In racemose type the rachis and peduncle donot, terminate by flowers but their apices are provided, with buds., In acropetal order the youngest flower is at the apex, while the oldest is at the base., In racemose inflorescence opening of flower is, centripetal i.e. the basal or outer flowers open first, and the apical or inner flowers open last., When the flower of the racemose inflorescence are, borne on an unbranched peduncle, the inflorescence, is called simple racemose inflorescence., In compound racemose inflorescence the peduncle, is branched and branches are borne over the mother, peduncle in acropetal order., The various forms of racemose inflorescence can, be described under–
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 256, , –, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , those in which the main axis is elongated, e.g., raceme, spike, spikelets, catkin, spadix., –, those in which the main axis is shortened,, e.g., corymb, umbel., –, those in which the main axis becomes, flattened, concave or convex, e.g. head., In raceme inflorescence, pedicillate flowers are, borne acropetally on an elongated inflorescence, axis, e.g. Brassica, Cassia., When the main axis of the raceme is branched and, the lateral branches bear the flowers then the, inflorescence is compound raceme or panicle,eg., Delonix, litchi, mango., Spike is the type of inflorescence where sessile, flowers are borne acropetally on an elongated, inflorescence., In compound spike the inflorescence axis of a spike, is branched and the branches bear sessile flowers, (flowers are arranged like that in spike). For example, Amaranthus spinosus., Spikelet is the compound inflorescence or, secondary spike which is common in grasses and, hedges, eg wheat., Catkin (amentum) is a special type of spike with, a long, thin and pendulous axis which bears, unisexual deciduous acropetally arranged sessile, flowers. For example oak, willow, mulberry (Morus), etc., The axis of the spikelet (ultimate branch) is called, rachilla., Each spikelet (locusta) bears two glumes (minute, bracts) at its base and inflorescence bears one to, many sessile flowers on a reduced stem. It bears, lemma and palea also. Above palea there are two, scale like lodicules (i.e. perianth), The rice inflorescence is described as panicle of, spikelets and each spikelet is composed of one, flower only., In wheat the spikelets are multiflowered and are, borne on an unbranched axis appearing as a, compounds spike., Strobile is a type of spike in which the sessile, flowers are borne in the axils of persistent, membranous bracts, e.g. hop (Humulus lupulus)., Spadix is a spike with a fleshy axis that is enclosed, by one or more large, often brightly coloured bracts, called spathes. For example in banana, Colocasia, etc., , l, l, , l, , l, , l, l, l, , l, , l, , l, , l, , l, , The spadix is found in monocots only., In coconut, palm, Pandanus, compound spadix is, present where the main axis of the spadix is, branched and the flowers are borne on the branches., Largest spadix inflorescence is present in, Amophophallus., Smallest spadix is present in lemnaciae., Woody spadix is found in Cocos nucifera., Corymb is similar to raceme but axis is short at the, top. As the lower flowers are long stalked and the, upper ones have a short stalked thus all the flowers, appear almost at the same level, eg. Iberis, Cassia, sp. etc., In umbel inflorescence due to condensation of the, axis, the flowers appear to be arising from one point, in a centripetal manner (outer flowers are more, mature)., The inflorescence in umbel is subtended by an, involucre, e.g., Hydrocotyl, Centella asiatica., The flowers in an umbel type of inflorescence, usually have stalks of equal length., When the axis of an umbel inflorescence is branched, and each branch bears equally pedicellate flowers, it is called compound umbel, e.g., fennel,, corriander, carrot. The involucres of the secondary, umbels are called involucels., In capitate inflorescence the axis is suppressed to, form a globose head and large number of sessile, flowers grow on it to give it a globose appearance., eg., babul (Acacia), siris (Albazzia)., Head or capitulum or anthodium inflorescence, consists of mono or dimorphic florets borne on, a condensed axis called receptacle., Although the whole inflorescence looks like a single, flower in head, it really consists of a clustered mass, of small sessile flowers called florets., Florets are usually of two kinds ray florets, (marginal) and disc florets (central tubular ones)., Mixed panicle ® e.g. Ligustrum vulgaree., Panicle of spikelets ® e.g. rice, Cymose Umbel ® e.g. Allium cepa, Calotropis., Cymose Corymb ® e.g. Ixora, Mixed Spadix ® e.g. banana, Thyrsus (a number of cymose clusters are borne, acropetally on an axis with unlimited, growth), e.g., Grapevine., Corymb of capitula ® Agerantum, The ray florets are neutral in sunflower and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , l, , l, l, , l, , l, , l, , pistillate in Tridex. The disc florets are generally, bisexual. Each floret has individual scaly bract., The florets in head are borne in acropetal manner, but they appear centripetal due to condensations, of the axis. The entire inflorescence is subtended, by an involucre of bracts at the base., The head are of two types homogamous head, and heterogamous head., In homogamous head monomorphic florets are, present. Only ray florets occur in Sonchus, Launea, etc. and disc florets in Ageratum, Vernonia etc., In heterogamous head dimorphic florets are, present. The ray florets are peripheral and bisexual, disc florets are central in position, eg. Dahlia,, Helianthus etc., Compound capitulum is formed when the main, inflorescence axis is branched and several capitula, are included within a common involucre., In compound capitulum each head has a single, floret subtended by its own involucre, eg., Echinops echinatus., , Cymose inflorescence, l, , l, , l, , l, , l, l, , l, , In cymose inflorescence the growth of the main axis, is limited and the rachis or peduncle apices, are terminated by flower (no further elongation of, the axis)., In cymose inflorescence the flowers are arranged, on the rachis laterally in basipetal succession i.e., the apical or uppermost flowers are older than the, basal (lower) flowers., On the basis of arrangement of flowers cymose, inflorescence are of different types as uniparous, (or monochasial cyme), biparous (or dichasial, cyme), multiparous (or polychasial cyme)., In uniparous cyme the main axis ends in a flower, and it produces only one lateral branch at its base, which also ends in a flower. The process is repeated., Two types of uniparous cymes are helicoid and, scorpioid., In helicoid uniparous cyme the lateral axis develop, successively on the same side (either on the left or, right side) of the main axis forming a helix, eg., sundew (Drosera), Bigonia, Heliotropium etc., Helicoid uniparous cyme are of two types , drepanium (when the lateral branches are in the, same plane), and bostryx (when the lateral branches, are in different plane)., , l, , l, , l, , l, , l, , 257, , In scorpioid monochasial cyme the successive, lateral branches develop alternately on the, opposite sides (to the right or left) of the main axis,, evidently forming a zigzag, e.g. Ranunculus,, Heliotropium etc., Scorpioid monochasial cyme are of two types –, rhipidium (when the lateral branches are in the same, plane, eg. Solanum nigrum) and cincinus (when the, lateral branches are in the different plane)., In biparous cyme or dichasium type the main axis, ends in a flower and at the same time it produces, two lateral branches which terminates in flowers., The latter branches may again branch similarly, eg., jasmine, Ixora, Dianthus etc., In multiparous cyme or polychasium type the, main axis ends in a flower and at the same time, produces more than two lateral branches which also, end in flowers. This process is repeated again, e.g.,, Calotropis., In cymose head, sessile/subsessile flowers are borne, centrifugally around a receptacle, eg.,, Anthocephalaus cadamba., , Mixed inflorescence, l, , Mixed inflorescence have both the characters of, racemes and cymose type of inflorescence., , Special types of inflorescence, l, , l, , l, , l, , l, , l, , Special type of inflorescence are basically cymose, but ultimately it is modified to form a special, appearance., Different types of special inflorescence are , cyathium, coenanthium, hypanthodium and, verticillaster., In cyathium the whole inflorescence is covered by, a cupshaped green involucre formed by the fusion, of bracts. Here extremely reduced florets are present, on a convex receptacle., In cyathium, the central, largest, single female flower, with a single pistil is surrounded by a number of, young male flowers (each reduced to a solitary, stamen) seated on short stalks., Each male flower in cyathium has a stalk and a scaly, bract at the base. The flower follow centrifugal order, of development i.e. the female flower at the centre, mature first and then the male flowers surrounding it., Cyathium is found in Euphorbia, Pedilanthus, (jew’s slipper) etc. Nectar secreting glands are often, present in cyathium.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 258, , l, l, , l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Coenanthium is a saucer shaped inflorescence with, margins curved upward, e.g. Dorstenia., Hypanthodium has a fleshy receptacle which forms, a hollow cavity more or less pear shaped with an, apical opening or ostiole., The ostiole of hypanthodium is guarded by, scales and flowers are borne on the inner side of, the cavity., The receptacle of hypanthodium is formed by the, condensation of the rachis of three cymes., In hypanthodium the female flowers are present at, the base and male flowers higher up towards the, mouth. Sterile or gall flowers are present in between, the male and female flowers. Example of, hypanthodium is Ficus., Verticillaster is condensed dichasial cyme., On the main axis there are two opposite bract at the, node. A large flower arises in the axil of each bract, and two small flower are borne on the side of such, a flower., All the three flowers are sessile or subsessile. Each, dichasial cyme changes into monochasial cyme of, scorpioid type. Thus there are 7 flowers in a cluster,, e.g., Ocimum., Inflorescence, Axillary, , Terminal e.g.,, Crotolaria, Racemose, (Indefinite), Raceme e.g.,, Cruciferae, Panicle e.g.,, Delonix, Spike e.g.,, Lilly, Catkin e.g.,, Casuarina, Spikelet, eg, wheat, Spadix e.g.,, Alocasia, Corymb, Iberis, Umbel e.g.,, Coriander, Capitate eg., Acacia, Head or, capitulum, , Cymose, (Definite), , l, , l, , Mixed, Thyrus, , Solitary e.g.,, Gossypium, Simple e.g.,, Bougainvillaea, Monochasial, Helicoid e.g.,, Hamolia, Scorpioid e.g.,, Brinjal, Dichasial e.g.,, Clesodendron, Polychasial, e.g., Calotropis, Cymose head, eg, Anthocepholus, , FLOWER, l, , l, l, , l, l, l, l, l, l, l, l, , l, , Intercalary e.g.,, Callistemon, , l, , Special, Cyathium, e.g.,, Euphorbia, Coenanthium, e.g.,, Dorstemia, Hypanthodium, e.g.,, Ficus, Vesticillaster, e.g.,, Ocimum, , l, l, , l, l, , l, l, l, , Flower is a specialised branch of limited growth, which bears floral leaves that carry on sexual, reproduction and give rise to seeds and fruits., The study of flowers is called anthology., Plants which flower only once in their life time, are called monocarpic, eg : Bambusa arundinacea,, Agave americana (century plant), annual crop plants., Plants which flower many times in their life time, are called polycarpic, eg : all perennial trees., Flowers are regarded as modified shoots for, sexual reproduction., Pedicel is the stalk of the flower., Flowers with stalk are pedicillate flowers and, without stalk are sessile flowers., In case of solitary flower, its stalk is termed as, peduncle., The tip of the pedicel is called thalamus or torus, or receptacle., Thalamus is formed by the condensation of, internodes of the floral axis., In case of underground modified stem, flowering, shoot that come out annually above ground is termed, scape, e.g. tuberose., The floral buds usually develop at the axils of small, specialised green leaves called bracts., A flower with bract at its base is called a bracteate, flower, e.g. Adhatoda and one without bract is called, as ebracteate flower, e.g. mustard., A bract may fall off early (deciduous) or may be, present even after fertilisation (persistent)., When additional bract like structures are borne on, the peduncle or the pedicel between the flower and, the bract they are termed as bracteoles, e.g., Leonurus., In scaly bracts, the bracts are scale like appendages,, e.g. cruciferae., In leafy or foliaceous bracts, the bracts resemble, green foliage leaves, e.g. Cleome viscosa, Adhatoda, vasica., In petalloid bract, the bracts are brightly coloured, e.g. Bougainvillea., Spathe is a large, thick, boat shaped bract that covers, a spadix inflorescence, e.g., Colocacia., Involucre (or involucel) is a whorl of bracts, subtending an inflorescence, e.g., umbel and, capitulum inflorescence.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, , l, l, l, , l, , l, , l, , l, l, , l, , l, , l, , l, l, l, l, l, l, , There are two lower whorls of accessory or non, essential organs (calyx and corolla) and two upper, whorls of reproductive or essential organs, (androecium and gynoecium)., Complete flower has all the four floral whorls., In incomplete flower any one of the floral whorl, is absent., When both nonessential whorls are present, the, flower is described as dichlamydeous and when, only one nonessential whorl is present, the flower, is called as monochlamydeous, e.g., Polygonum., When both the nonessential whorls are absent, then the flower is said to be achlamydeous or naked,, e.g., betel., When both the essential whorls are present then, the flower is described as bisexual or, hermaphrodite., When only one essential whorl is present, then, the flower is describe as unisexual or diclinous, either staminate (male flower androecium) or, pistillate (female flower gynoecium)., In heterochlamydeous flower the two nonessential, whorls possess different colours, eg. Hibiscus., In homochlamydeous flower the two nonessential, whorls possess same colour, eg. Artabotrys,, majority of the monocots., When both the essential whorls are absent, the, flower is designated as neutral or aclinous, e.g.,, in inflorescence of Hydrangea., The four whorls develop in an ascending order from, the swollen, supressed end (thalamus) of the floral, axis or stalk (pedicel)., The androecium is the male whorl and each of its, stamen differentiates into a filament, anther and, connective., Gynoecium or pistil is the female whorl that is, differentiated into the ovary, style and stigma., A plant bearing both male and female flowers is, said to be monoecious, e.g., gourd., A plant bearing either male flowers or female, flowers is called dioecious, e.g. mulberry, papaw etc., In trioecious plants male, female and bisexual, flowers are present on separate plants, eg. Silene., In andromonoecious plants male and bisexual, flowers are present on the same plant, eg : Veratrum., In gynomonoecious plants female and bisexual, flowers are present on the same plant, eg. asteraceae, plants with heterogamous head inflorescence., , l, l, , l, , l, , l, l, , l, l, , l, , l, l, , l, , l, , l, , l, , 259, , In gynodioecious plants female and bisexual, flowers are present on different plants, eg. Thymus., A plant bearing bisexual, unisexual and even, neuter flowers is said to be polygamous, e.g.,, Polygonum, mango., In cyclic flowers (whorled) sepals, petals, stamens, and carpels are arranged in circles or whorls round, the thalamus., In acyclic flowers (spiral) sepals, petals, stamens, and carpels are spirally arranged, e.g., Magnolia,, custard apple., The flower may be hemicyclic when some parts are, cyclic and others acyclic as in rose., When the floral parts are different in number in each, whorl it is called anisomerous flower, eg. Achras, sapota., In isomerous flower floral parts are uniform in, number or multiple in number in all whorls., When all the floral organs are similar in their size,, structure and order of disposition, the flower is said, to be regular or actinomorphic, e.g., in carrot, rose,, sunflower., Flower is said to be irregular or zygomorphic if, any series show dissimilarity in its parts regarding, any of their traits., Assymetric flower cannot be cut into two equal, parts in any plane., According to the position of gynoecium, the, flowers are of three kinds as hypogynous,, perigynous and epigynous., When the calyx, corolla and androecium arise below, the ovary, the flower is described as hypogynous., The ovary is superior, e.g., cruciferae, liliaceae., When the calyx, corolla and androecium arise from, the around of ovary, the flower is described as, perigynous. In these flowers the ovary is semi, inferior, e.g., Saxifraga., When the calyx, corolla and androecium arise from, the top of the ovary, the flower is described as, epigynous and the ovary is inferior, eg. myrtaceae,, umbelliferae, compositae etc., Depending upon the number of floral parts,, flowers of different types as –, –, dimerous, e.g. Papaver etc. (floral parts in, the multiple of 2), –, trimerous, e.g. monocots (floral parts in the, multiple of 3)., –, tetramerous, e.g. cruciferae (floral parts in, the multiple of 4).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 260, , –, –, , ŕďőĽę– ĐĽŐńŐĹť, , pentamerous, e.g. malvaceae, solanaceae, (floral parts in the multiple of 5), hexamerous, e.g. Argemone (floral parts in, the multiple of 6)., , Parts of flower, l, l, , l, , l, , A typical flower has four main parts – calyx,, corolla, androecium and gynoecium., The individual units of a calyx are sepals, of a, corolla are petals, of an androecium are stamens, or microsporophylls and of a gynoecium are, carpels or megasporophylls., Calyx and corolla are helping or accessory whorls, because they attract insects during pollination and, protect the essential parts before the flower bud has, opened., Androecium and gynoecium are essential or, reproductive whorls as they are necessary for, sexual reproduction and seed formation., , Calyx, l, Calyx is the outermost, lowermost, non essential but, protective whorl of the flower., l, Calyx or sepal is composed of green leaf like, structure., l, When sepals are coloured other than green, they are, called petaloid., When the sepals are free from one another, the, l, calyx is said to be polysepalous, e.g., mustard, water, lily etc., l, When the sepals are wholly or partially united with, one another by their margins, then the calyx is said, to be gamosepalous, e.g., brinjal, chilli., Calyx may show various shapes like campanulate, l, (bell like, eg., Petunia), cupulate (cup like, eg., Gossypium), urceolate (urn shaped, eg. silene), infundibulum (funnel shaped, eg., Atropa),, globose (inflated, eg., Physalis), tubular (eg.,, Verbena), bilabiate (2lipped, e.g., Salvia),, spurred (beak like, e.g., Larkspur), hooded (one, sepal enlarged to form a hood, e.g., Aconitum),, spinous (modified into spines, e.g., Trapa),, pappus (hairy, e.g., Sonchus), saccate (pouched,, e.g., mustard), reflexed (bent backwardly, Cassia),, gland dotted (e.g., Citrus)., Calyx can be differentiated on the basis of their, l, duration as caducous, deciduous and persistent., l, In caducous type, the calyx fall off just after, opening the bud, e.g. Argemone, Papaver etc., , l, l, l, l, , In deciduous type , sepals fall off along with petals, just after fertilisation, e.g. mustard., In persistent type, sepals remains attached with the, ripe fruit, e.g. Pisum, Ocimum, solanaceae., Persistent calyx growing in size along with fruit, (e.g., Physalis) is called accrescent calyx., Epicalyx is an extra series of green sepal like floral, organ which lies on the outside of calyx, e.g.,, malvaceae., , Corolla, The inner non essential attractive whorl, proceeding, l, towards the centre is called corolla., l, Corolla are brightly coloured and attract insect, for pollination and protect the inner essential, whorls from injury., When a petal looks like a sepal it is called sepaloid, l, petal, e.g., Anona, Polyalthia., l, The petals may be differentiated into a limb, (expanded part) and a claw (narrow part) or, unguis., l, When stalked, the petals are described as clawed, or unguidculate, e.g., cruciferae and when the claw, is absent the petals are sessile, e.g., rosaceae., When the petals within the corolla remain free from, l, one another then corolla is said to be polypetalous,, e.g., mustard etc., l, When the petals are united by their lateral margins, then the corolla is said to be gamopetalous, e.g.,, Datura, gourd etc., l, In a gamopetalous corolla, the petals unite to form, a lower tubular portion known as corolla tube and, the upper free portion is known as corolla lobes., l, Shape of polypetalous corolla are cruciform,, caryophyllaceous, rosaceous and papilionaceous., In cruciform type four free petals are diagonally, l, arranged in relation to floral axis, e.g., Brassica., l, In caryophyllaceous type five or more free petals, with long claws are present, e.g., Dianthus., l, In rosaceous type five or more free petals with short, claws are present, e.g., Rosa., l, Papilionaceous corolla has butterfly shaped corolla., It consists of five free dissimilar petals of which, the outermost one is the biggest and is called the, standard or vexillum, two postero lateral petals, called alae and two antero lateral petals (smallest), fused to form the carina or keel, eg., pea, bean,, gram.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, , l, , l, , l, l, , l, , l, , l, l, , Gamopetalous corolla are of different shapes like, campanulate (eg. Cucurbita), hypocrateriform or, salvar shaped (tubular with spreading lobes, e.g.,, Clerodendron), infundibulum (e.g., Petunia),, urceolate (e.g., Bryophyllum), tubular (e.g.,, sunflower), ligulate (strap shaped, e.g., ray florets, of sunflower), rotate (short tube with spreading, lobes e.g., Solanum nigram), spurred (Delphinium),, bilabiate (Salvinia)., When a pouch like outgrowth arises at the base of, the corolla then such type of corolla is described as, gibbous, e.g., Antirrhinum., In monochlamydeous flower when single accessory, whorl is present (no distinction between sepal and, petal), the whorl is described as perianth., Unit of perianth or individual member of, perianth is known as tepal., When the members of perianth are free the perianth, is termed as polyphyllous, e.g., Polygonum,, Asparagus etc., When the members of perianth are united the, perianth is termed as gamophyllous, e.g.,, Polyanthes., When the perianth is bright like petals it is called, petaloid perianth as in glory lily, water hyacinth, etc., If the perianth is sepal like it is called sepaloid, perianth as in Acalypha indica, Phyllanthus niruri., In grasses the perianth is scale like and is called, lodicule., , Androecium, Androecium is the outer essential whorl consisting, l, of stamens., l, Each stamen is distinguishable into anther and, filament., l, Each anther consists of two anther lobes attached, at the back by a sterile band called connective and, each lobe contains two microsporangia., l, Sterile and undeveloped stamens are called, staminodes., All stamens are with filaments but in some special, l, cases stamens are without filaments (sessile, condition) as in Arum maculatum., l, The number of stamens present within a flower, varies from one to many. Based upon this the, condition is called monandrous (when number is, one), e.g., ginger; diandrous (two), e.g., Adhatoda;, triandrous (three), e.g., wheat; tetrandrous (four), , l, , l, l, , l, , l, , l, , l, l, , l, l, l, l, , l, , l, , l, , 261, , e.g., Ocimum; pentandrous (five), e.g., Datura;, hexandrous (six), e.g., paddy, polyandrous (many),, e.g., rose., When the stamen number is equal to the petals or, sepals, they are described as isostemonous or, haplostemonous, e.g., brinjal., When the stamens differ in size or mode of, dehiscence, they are called heterostemonous., Stamens may be alternipetalous (alternating with, petals, e.g., Petunia), antipetalous (opposite to, petals, e.g., corriander), alterniphyllous (alternate, to sepals) and antiphyllous (opposite to sepals)., When the number of stamen is double the petals, (arranged in two whorls) and outer whorl lies, opposite the sepals, they are described as, diplostemonous, e.g., Geranium., When the number of stamens is double the petals, and the outer whorl lies opposite the petals, the, stamens are described as obdiplostemonous, e.g.,, Oxalis., When the stamens are in more than two whorls, the, condition is described as polystemonous, e.g.,, Delphinium, Aquilegia etc., In Delphinium, stamens are spirally arranged and, they are described as spirocyclic., The union of stamens may take place either among, themselves (cohesion) or with other floral members, (adhesion)., In syngenesious condition fusion of anther occur, only and filaments remain free, e.g., sunflower., In synandrous condition both anthers and filaments, remain fused, e.g., cucurbitaceae., When there is no fusion, the androecium is described, as polyandrous, e.g., cruciferae., In adelphous condition stamens are united only by, their filaments forming one to several bundles but, the anthers remain free., Different terms are used to describe the fusion of, filaments in different plants as monadelphous, (fusion in one bundle e.g., china rose), diadelphous, (fusion in two bundles, e.g., papilionaceae),, polyadelphous (fusion in more than two bundles, e.g., Citrus)., Condition in which filament of stamens are attached, to corolla or petals and anthers are free is called, epipetalous, e.g., brinjal, potato etc., In episepalous condition stamens are attached to, the sepals, e.g., Quisqualis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 262, , l, l, l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , When the stamens are fused with tepals they are, described as epiphyllous, e.g., liliaceae., When the stamens are fused with carpels they are, described as gynandrous, e.g., Calotropis., When the union between stamens and carpels is, complete i.e. throughout then condition is called, gynostegium (Calotropis) or only by apex it is called, gynostemium (orchid)., When two stamens are long and two are short as in, labiatae, acanthaceae, the condition is said to be, didynamous., In tetradynamous condition four stamens are long, and two are short, e.g., cruciferae., When the connective is very narrow, so that the two, anther lobes lie in close proximity as in Adhatoda,, Euphorbia sp, it is called discrete., When the connective is broad and the two anther, lobes are separated as in Tilia sp, it is called, divaricate., When the connective is elongated long stalk like, present at right angle to the filament and subtending, one fertile anther lobe at one end and one sterile, anther lobe on the other end as in Salvia sp, it is, called distractile., In adnate anther, filament is attached to the, complete length of the anther i.e. from base to apex, of anther., When the filaments appear to be attached to the base, of the anthers, then the condition is basifixed, or, innate, e.g., Raphanus., When the filaments appear to be attached to the, anthers abaxially, they are described as dorsifixed, e.g., malvaceae, Sesbania., When the filament is attached at one point and the, anther hangs over it showing seesaw movement, they, are described as versatile, e.g., grass., The anthers are generally linear elongated structure, but in some flowers they have other shapes also like, reniform i.e. kidney shaped (Hibiscus), sagittate i.e., arrow shaped (apocyanaceae), sinuous i.e. lobed in, Slike manner (cucurbitaceae)., A one celled or lobed anther having only two, microsporangia or pollen chambers as in malvaceae, is called monothecous anther., A two celled or lobed anther having four, microsporangia or pollen chambers is called, dithecous anther, e.g., cruciferae., Dehiscence of anthers may be longitudinal, , l, l, l, , (lengthwise slits, e.g., Datura, mustard), transverse, (breadthwise slits, e.g., Malva), valvular (anther, lobe breaks at places by lifting of surface layers,, e.g., barberry), porous (by pores, e.g., Solanum),, irregular (e.g., Najas)., The anther dehiscing towards periphery of flower, as in malvaceae is called extrose anther., The anther dehiscing towards the centre of flower, is called introse anther., Appendages of the stamens are called staminal, corona., , Gynoecium, l, Gynoecium constitutes the inner essential whorl, of flower comprising carpels., Carpel is the unit of gynoecium and it is, l, distinguishable into basal ovule bearing region, (ovary), a terminal pollen receiving region (stigma),, joined by stalk like structure (style)., l, A sterile pistil or gynoecium or ovary is known as, pistillode, e.g., male flowers of hypanthodium., The word pistil is derived from the latin term, l, Pistillum, “pestle”., l, The number of carpels is usually fixed for a plant, species and it is described as monocarpellary, (single carpel), bicarpellary (two carpels),, tricarpellary (three carpels), tetracarpellary (four, carpels), pentacarpellary (five carpels) to, multicarpellary (usually having more than five, carpels)., In compound gynoecium if the carpels remain, l, completely free from one another it is termed, apocarpous, e.g., lotus, rose; but if carpels are fused, with each other then it is called syncarpous, e.g.,, cruciferae., l, The term locule refers to the intraovarian chamber, or compartments of ovary., Depending upon the number of locule, the ovary, l, is termed as unilocular (1 locule), bilocular (2, locules), trilocular (3 locules), tetralocular (4, locules), pentalocular (5 locules), or multilocular, (more than 5 locules)., l, Generally number of ovary corresponds with the, number of carpels but in Datura etc., number of, chambers increases due to false partition or septum, called replum i.e., bicarpellate pistil having two, chambered ovary becomes four chambered., l, The swollen place of the ovary where the ovules, are attached is called placenta.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, l, l, , l, , l, , l, , Arrangement of ovules inside the ovary on placenta, is called placentation., Main types of placentation are axile, marginal,, parietal, free central, basal and superficial., Axile placentation is found in bi to multi, carpellary, bi to multilocular ovary and ovules are, borne on central axile column mound on axis, e.g.,, in malvaceae, solanaceae., Marginal placentation is found in monocarpellary, (unilocular) ovary and ovules are borne on margin, e.g., in family fabaceae., Free central placentation is found in bi to, multicarpellary, unilocular ovary and ovules are, borne on central mound axile column not, connected to the ovary wall by any septum, e.g., in, caryophyllaceae (Stellaria)., Parietal placentation is found in bi to, , Table : Some important definitions, Term, Character, Eg, Turning or twisting Orchids, Resupination, of ovary or flower, through 180º, i.e.,, upside down, Phyllody, chloranthy, Anthesis, Anthophore, , or Transition from, sepals to stamens, through petals, , l, l, l, l, l, , l, , Opening of flower, , The, elongated, internode between, androecium and, gynoecium, , Capparis, , Zynandrophore When androphore, and gynophore, or, androgynophore both are present in, the same flower., , Cleome, gynandra, , Carpophore, , l, , l, , Silene, , Gynophore, , l, , Nymphea, , The, elongated, internode between, calyx and corolla, The, elongated, internode between, corolla, and, androecium, , Androphore, , l, , The prolongation, of thalamus beyond, carpels, , Passiflora, , l, , l, , 263, , multicarpellary, unilocular ovary and ovules are, borne on periphery, e.g., Papaver, Argemone., Basal placentation is found in mono to tricarpellary,, unilocular ovary. Ovules may be few or reduced to, one which are borne at the base of ovary, e.g.,, sunflower (compositae)., Superficial or laminar placentation is found in, multilocular ovary and ovules are borne on inner, surface or partition walls, e.g., in waterlily, (Nymphea)., The stalk of ovule is called funicle., Funicle is useful for the attachment of ovule to, the placenta., Style may be terminal, lateral or gynobasic based, on the position on the ovary., Style is terminal in position when it arises from the, top of the ovary, e.g., chinarose, mustard., Style is lateral in position when it arises from one, side of the ovary as in mango., Gynobasic style is characteristic feature of family, labiatae (Ocimum) were style arises from the, depression or cavity in the centre of ovary or directly, from thalamus., When base of the style is swollen to form a pad like, structure, it is called stylopodium, e.g., in, umbelliferae (corriander)., The styles are generally deciduous i.e., they fall, off after fertilisation but in Clematis they are, persistent and feathery., Depending upon their shapes, the stigmas have, been variously described. They may be bifid, (compositae), dome shaped (Brassica), funnel, shaped (Crocus), striate (Papaver)., Feather like stigma is called plumose stigma as in, grasses (gramineae)., , Aestivation, l, , l, , Coriandrum, , l, l, , The mode of arrangement of the sepals or petals, with respect to one another in the floral bud is termed, as aestivation., Aestivation is of the different types as – valvate,, twisted or contorted, imbricate, quincuncial,, vexillary, convolute, and plicate., In valvate aestivation, sepals or petals or tepals just, touch without any overlapping, e.g., Brassica., In twisted or contorted type, one margin of each, petal overlaps the margin of an adjacent petal and, the other margin being overlapped by margin of, another adjacent petal, e.g., china rose.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 264, , l, l, , l, , l, , Imbricate is aestivation of five parts, where one is, exterior, one is interior and rest three are having one, margin exterior and other interior., Vexillary is characteristic aestivation of corolla, of pea where posterior petal is outermost., Quincuncial is aestivation of 5 parts, where two, are exterior, two interior and the fifth is having one, margin exterior and the other interior., Convolute type is a modified form of contorted, aestivation and applied when the entire petals are, involved in twisting, e.g.Phlox., When each petal is folded like a fan along its midrib, and with margins fused then the condition is called, as plicate, e.g., Datura., , FRUIT, l, , l, l, l, , l, , l, , Fruit is the matured ovary or ovaries, with or, without seeds together with any accessory structures, closely associated with them., Pomology is the study of fruits., After fertilization ovary forms fruits and ovules, form the seeds., Fruits are classified on the basis of the, –, floral parts that participate in the fruit, development,, –, nature of pericarp,, –, union of carpels,, –, type of dehiscence., On the basis of the formation of fruits, they are, classified into – (a) true fruits and (b) false fruits, (or spurious fruits or pseudocarps)., The fruits which are developed only from the ovary, , and in which no other floral parts take part in its, development are called true fruits., The fruits in which addition to ovary other floral, parts also contribute for its development are, called false fruits, e.g, aggregate fruits., A fruit that is formed without fertilization and, thus without seed is called seedless fruit or, parthenocarpic fruit, e.g., banana., Noll defined parthenocarpy as the development of, fruit without any stimulus by other factors., Modified definition of parthenocarpy is formation, of fruit without fertilization., The fruits that develops out of fertilization and, possess seed is termed seeded fruits., The mature wall of the ovary after ripening in the, fruit is called pericarp (peri around, karpos fruit), , l, , l, , l, l, l, l, , Pericarp, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Outermost layer Epicarp (skin of the fruit), Middle region Mesocarp, (may be thin and membranous in orange, hard, and stony in palms, fleshy and juicy in mango etc.), , Innermost layer, , Types of fruits, l, l, l, , l, , There are three main types of true fruits (a) simple, fruits (b) aggregate fruits, (c) composite fruits., Simple fruits develop from monocarpellary or, multicarpellary syncarpous ovary., Aggregate fruits develop from the multicarpellary, apocarpous ovary. A single part of fruit is called, as fruitlet., Composite fruit develops from entire, inflorescence with its flowers and peduncle etc., Fruits, , Simple fruits, Simple dry, Indehiscent, , dehiscent, , Aggregate fruits, , Simple fleshy, , Schizocarpic, , drupe, pome, , Composite fruits, , etaerios of, follicles, etaerios of, achenes, , Achene, , Legume, , Lomentum, , Nut, , Follicle, , Cremocarp, , berry, pepo, , etaerios of, drupe, , Cypsella, , Siliqua, , Double Samara, , hesperidrum, , etaerios of, berry, , Caryopsis, , Siliqula, , Regma, , amphisarca, , Samara, , Capsule, , Carcerulus, , balausta, , Sorosis, , Syconus
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , Simple fruits, Simple fruits is divided into two groups – dry and, l, fleshy fruits., l, The simple dry fruits are with dry membranous,, leathery or woody pericarp., The dry fruits on the basis of dehiscence is again, l, divided into three groups indehiscent, dehiscent, and schizocarpic., l, The fruits that do not burst or split open at maturity, are called indehiscent fruit. These fruits are single, seeded as in achene, caryopsis, cypsella, nut and, samara., l, Achene is developed from a monocarpellary, superior one chambered ovary. The fruit is dry, one seeded where pericarp (fruit wall) and testa (seed, coat) are free from each other as in Mirabilis jalapa,, Clematis etc., Caryopsis is a small, dry, indehiscent one seeded, l, fruit developing from monocarpellary simple, pistil where the pericarp is fused with testa as in, rice, wheat, maize, grass etc., l, Caryopsis is commonly known as grains., l, Cypsella is a dry, indehiscent, one seeded fruit, developing from a bicarpellary syncarpous, inferior ovary with the pericarp and the testa free, as in sunflower, marigold, cosmos etc., Nut is a dry indehiscent, one seeded fruit,, l, developing from a superior bi or multicarpellary, syncarpous pistil, where the pericarp is either hard, woody or leathery at maturity, e.g., hard woody, pericarp as in oak, or soft leathery pericarp as in, litchi., l, Samara is one seeded fruits developing from, superior, bi or tricarpellary ovary. Pericarp, becomes flat like wings, e.g., elm, chilbil., l, In the sal tree, wood oil tree etc., fruit is winged but, here wings are the dry, persistent sepals. This type, of winged fruits are called samaroids., The fruits in which pericarp rupture automatically, l, on ripening and discharge their seeds are called, dehiscent fruits., l, Different types of dehiscent fruits are legume or, pod, follicle, siliqua, silicula and capsule., l, Legume or pod is a dry monocarpellary fruit, developing from a superior, one chambered ovary, and dehiscing by both the sutures as in pea, bean,, pulse., , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , 265, , Follicle is a dry dehiscent fruit developing from, monocarpellary, superior, one chambered ovary, but dehiscence by one suture only., Single follicle is rare, sometimes seen in Calotropis., Follicle usually develop in an aggregate of two, three, or many fruits, e.g., Michelia, Vinca etc., Siliqua is a dry, dehiscent fruit developing from, a bicarpellary falsely two chambered, superior, pistil and dehiscing from below upwards by both, the margins while the seeds remain attached to the, false septum, the replum, as in mustard, radish., Silicula is a short, broad and flat siliqua found, in some members of cruciferae like candytuft, (Iberis), shepherds purse (Capsella) etc., Capsule is a many seeded, uni or multilocular fruit, developing from a superior (or sometimes, inferior), bi or polycarpellary ovary and dehiscing, in many ways, e.g., poppy, cotton etc., Schizocarpic fruits split up at maturity into one, seeded parts in such a manner that a portion of the, pericarp always surrounds seed., Different types of schizocarpic fruits are–, lomentum, cremocarp, double samara, regma,, carcerulus., Lomentum is a type of dry, indehiscent legume, constricted or partitioned between the seeds into, a number of one seeded compartments, (mericarps), e.g., Acacia, Arachis hypogea etc., Cremocarp is a dry, indehiscent, two chambered, fruit developing from an inferior, bicarpellary, ovary. On maturation it divides into one seeded, pieces called mericarps., Number of mericarp is equal to the number of, carpels and the mericarps in cremocarp remain, attached to the prolonged end (carpophore) of the, axis., Cremocarp is the characteristic fruit of, umbelliferae, e.g., corriander, cumin, fennel etc., The double samara fruits develop from, bicarpellary, syncarpous, superior ovary. Pericarp, develop into two wings. On maturation divides into, two seeded samara, e.g., Acer., In regma, fruits develop from multicarpellary, pistil and on maturation split and divide into as, many parts equal to the number of carpels., Each one seeded part in regma is known as coccus, e.g., castor has 3 cocci.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 266, , l, , l, l, l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Carcerule is small, dry indehiscent, four chambered, fruit developing from a superior, bicarpellary, pistil. This is a fruit characteristic of labiatae, e.g.,, Ocimum., Fleshy fruit are indehiscent and usually remain, succulent and juicy at maturity., The main types of fleshy fruits are drupe, pome,, berry, pepo, hesperidium, amphisarca, balausta., Drupe is a fleshy one or more chambered and one, or more seeded fruit developing from a, monocarpellary or multicarpellary, syncarpous,, superior ovary., In drupe pericarp is differentiated into epicarp, which forms skin of the fruit, the mesocarp which, is fleshy and the endocarp which is hard and stony., Hence drupe is also known as stone fruit., Examples of drupe are – mango, coconut, peach,, cherry, almond, etc. In mango, mesocarp is fleshy, and juicy whereas it is dry and fibrous in coconut., Berry or Bacca develops from mono or, multicarpellary superior or inferior syncarpous, ovary with axile and parietal placentation., Epicarp of berry forms the rind of the fruit, mesocarp, is fleshy and endocarp is thin membranous, e.g.,, tomato, banana, brinjal, guava etc., Berry that develops from a superior ovary is called, superior berry and which develops from inferior, ovary it is called inferior berry., The only hard part in berry is seed., Pome is an inferior, two or more celled, fleshy,, syncarpous fruit surrounded by thalamus. Pome, is a false fruit., In pome, fleshy edible part is composed of the, thalamus, while the actual fruit lies within, e.g.,, apple, pear, rose apple etc., Pepo is a fleshy many seeded fruit that develops, from an inferior tricarpellary ovary with parietal, placentation. It is characteristic fruit of family, cucurbitaceae, e.g., cucumber, water melon etc., Hesperidium is a superior many celled fleshy fruit, developing from a syncarpous pistil with axile, placentation, e.g., citrus fruits., In hesperidium, epicarp becomes thick and, leathery with oil gland, mesocarp is white,, fibrous and fused with epicarp whereas endocarp, is membranous from which unicellular, juicy, , l, , l, , l, , l, , hairs arise which form the edible part., In balausta, fruits develop from multilocular, syncarpous inferior ovary. Testa is fleshy and, fruit has persistent calyx, e.g., pomegranate., In pomegranate the pericarp of the fruit is tough, and leathery and the chambers are made of thin walls, of carpels. The edible portion is the succulent testa., Amphisarca develops from multicarpellary,, syncarpous, multichambered superior ovary., Fruit is many seeded with woody pericarp., Mesocarp, endocarp and swollen placenta are eaten, as in wood apple (Aegle marmelos)., All fruits with no hard parts excepting the seeds are, called baccate or berry like fruit and it includes, berry, pepo, hesperidium, amphisarca and balausta., , Aggregate fruits, Aggregate fruits develops from a single flower, l, with many free carpels and ovary (multicarpellary, apocarpous ovary). They make aggregate of fruitlets, Table : Methods of fruit dehiscence, Method, Feature, Eg., Sutural, Fruit dehisce by one, In follicle, suture, (Calotropis ) or by, two sutures, (legumespea and, bean), Porous, Found in capsule fruit. Papaver, Pores are formed on, the upper side of the, fruit, through which, seeds are dispersed., Transverse Pericarp dehisces, Celosia (Cock’s, transversely into two, comb), Ecalyptus,, portions. The cap like Psidium guajava, portion is blown away, by wind., Loculicidal Pericarp splits through, the middle of locules, along with division of, placenta., Septicidal Septa gets ruptured, and locules are, separated. Pericarp, also gets separated in, the forms of valves, , Gossypium,, Hibiscus, , Linseed, Castor,, mustard., , Septrifragal Placenta remains, Datura, Cedrela, attached in the centre, of fruit and pericarp, segments get separated
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 268, , l, l, l, , l, l, l, l, l, , l, l, l, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Seed is a dormant structure containing protective, coverings, reserve food and embryo (2n)., Outer protective covering of the seed is called seed, coat, which develops from integuments of ovule., In seeds developing from bitegmic ovules, there are, two distinct layers in seed coat. The outer layer, is thick, hard and leathery (developing from outer, integument), called testa, whereas inner layer is, thin and papery (developing from inner integument),, called tegmen., Seed coat is membrarous, generally fused with fruit wall., In seeds developing from unitegmic ovules there, is single layered seed coat., The seed is attached to the fruit wall or pericarp by, means of a stalk called funicle or funiculus., The point of attachment of funiculus to the body of, mature seed is called hilum., A small opening or pore called micropyle is present, just below the hilum, which is the way of entry, of water into the seed., Seeds may also show marking of chalaza for the, area where the integuments of ovule originate., The seeds having endosperm are called endospermic, or albuminous seeds, e.g., cereals, castor, etc., Seeds in which endosperm is fully consumed by, embryo and no endosperm is left, are called non, endospermic or exalbuminous seeds, e.g., gram,, pea, sea cucumber, tamarind etc., Monocotyledonous seeds are endospermic but some, as in orchids are nonendospermic., The endosperm is bulky and stores food., Outer covering of endosperm separates the embryo, by a proteinous layer called aleurone layer., The embryo is small and situated in a groove at one, end of the endosperm., –, –, –, –, , Endospermic dicot seeds : e.g., castor,, papaya, cotton., Nonendospermic dicot seeds : e.g., gram,, bean, pea, cucumber, tamarind., Endospermic monocot seeds : e.g., maize,, rice, wheat., Nonendospermic monocot seeds : Pothos, (money plant), Vallisneria, Alisma,, Amorphophallus., , l, l, , l, l, , l, , l, l, l, , l, , Embryo is the future plant and its origin is from, fertilized eggs or zygote., The embryo is having an embryonal axis or main, axis called tigellum., To the tigellum one (in case of monocot) or two (in, case of dicot) cotyledons are attached., The portion of embryonal axis or tigellum below, the point of attachment of cotyledons, is called, hypocotyl, which bears radicle or future root at, its tip., Portion of embryonal axis or tigellum above the, point of attachment of cotyledons, is called, epicotyl, which bears plumule (future shoot) at, its tip., Plumule occurs on the side of the single cotyledon., The epithelial layer is present for absorption of, nourishment from the stored food., Radicle is often covered by root cap and a special, protective sheath called coleorhiza., Plumule is surrounded by a protective sheath of, coleoptile., , DISPERSAL OF SEEDS AND FRUITS, l, , l, , l, , l, l, , l, l, , Dispersal is the process of carrying over of the fruits, and seeds to distant places (away from the mother, plant) by various external agents., Dispersal is essential to avoid struggle for, existence, for colonization of new areas and, production of mixed population., Dispersal is facilitated by various agents like wind, (anemochory), water (hydrochory), animals, (zoochory) and by explosion (autochory)., Anemochory is the mode of dispersal of fruits and, seeds by wind, eg Calotropis., Hydrochory is the mode of dispersal of fruits and, seeds by water of aquatic or near water plants,, eg Nymphaea., Some fruits and seeds are dispersed by animals, the, method termed as zoochory, eg Xanthium., The fruits burst due to compression or release of, pressure to throw or scatter the seeds to a distance, away from the mother plant. This process is termed, autochory, eg Impatiens.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 270, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 30, , Anatomy of Flowering, Plants, l, , l, , l, , l, , l, , l, , l, l, , Study of internal structure exposed after dissection, and opening of various parts is called anatomy., (Greek, ana again, tommein to cut)., In common usage anatomy is studied with naked, eyes. However, naked eye is unable to study much, internal structure in plants., Plants possess cells organised into tissues and tissues, organised into tissue systems which can be studied, only with the help of microscope., Histology (Greek hostos web, logos science) is, the study of tissues, their composition, structure and, organisation as observed with the help of, microscope. For plants, the terms, anatomy and, histology are synonymous interchangeable., Importance of anatomy are –, –, It gives information about internal structure, of different parts of an organism., –, Simplicity or complexity of structure is known, only through the study of internal structure., –, It is important for the study of phylogeny and, evolution., –, It has been used in resolving taxonomic, problems., –, On the basis of anatomical studies, wood is, used variously for cabinet work, musical, instrument, furniture, paper, match box,, pencils, sports articles etc., –, Forensic science studies plant anatomy in order, to identify plant remnants., Anatomical details indicate the structural, modifications in response to environmental, condition., A group of cells having similar origin, same method, of development and same function constitute tissue., The term tissue in plant anatomy was coined by N., Greew (1682)., , l, l, , l, l, , A tissue is formed in response to a basic division, of labour., Based on the capacity to divide, plant tissues are, classified into two main groups : meristematic, and permanent., A tissue is called simple tissue if it consist of only, one type of cells, eg., meristem, parenchyma., A complex tissue has two or more types of cells, which of course have a common origin & common, function, e.g., xylem & phloem., , MERISTEMATIC TISSUE, l, , l, l, , l, , l, l, , l, l, , l, l, , Meristematic tissues (Greek meristosdivisible) is, a simple plant tissue of thin walled embryonic cells, which undergo mitosis forming new cells & tissues., Term meristematic was introduced by Nageli (1858)., Cells of meristematic tissue are isodiametric in, shape (with prominent nuclei and dense, cytoplasm)., Cells are of various shapes like oval, spherical,, rounded or rectangular and lacks intercellular, spaces., Protoplast is present but ergastic substance are, absent, ER small, mitochondria simple., Meristematic cells of vascular cambium are, fusiform in shape, contain ergastic substances like, starch grains and tannins., Meristematic cells form two types of cells :, initiating cells and permanent cells., The meristematic cells which retain their capacity, of division throughout their life are called initiating, cells., Cells which loose their power of cell division and, become mature are called permanent cells., The meristem which forms the new tissue or organ is called, promeristem or embryonic or primordial meristem.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňďŚŐŇť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, l, l, l, l, l, l, l, l, l, l, , l, l, l, , l, , l, , l, , l, , l, , l, , Promeristems are usually found in root apex or, shoot apex., On the basis of the plane of division meristem can, be classified as mass, plate and rib meristem., Mass meristem divides in all planes,, eg., endosperm., The plate meristem divides in two planes; right, angle to each other, eg. epidermis., Rib meristem divides in one plane only, eg. certain, cells of pith and cortex., Based on mode of origin meristem are classified, into two types primary and secondary., Meristem that originate from the embryonic, meristem is called primary meristem., These are located at the tip of stem, roots and, appendages., Meristem that originate from permanent cells are, called secondary meristem., Secondary meristem is formed at lateral position, of the axis and parallel to surface., Example of secondary meristem are cork, cambium, interfascicular cambium & cambium in, roots., On the basis of the position meristem can be classified, as – apical, intercalary and lateral meristem., Apical meristem are usually found at the apical, region of stem, root and lateral appendages., Apical meristem is terminal in position and are, responsible for terminal growth of the plant, apices., Intercalary meristem get detached from the mother, meristem and present in between the permanent, cells., Intercalary meristem is present in grasses at the, basal regions of internodes and in leaf sheath of, monocots., Intercalary meristem are short lived. On loosing, their power of division they merge with permanent, tissue., Lateral meristem are responsible for increase in, thickness of the axis, eg. vascular cambium or cork, cambium., On the basis of function meristem can be classified, into three types – protoderm, procambium and, ground meristem., Protoderm is the outermost layer of apical, meristem from which rises epidermis of stem and, epiblema of root., , l, l, l, l, l, l, , l, , l, l, , l, l, , l, , 271, , Meristem which develops into primary vascular, tissue is called procambium., The derivatives of procambium is differentiated into, phloem and xylem., Meristem which develops into ground or, fundamental tissue is called ground meristem., Shoot apex is portion of shoot above youngest, primordium., Plastochron is the time gap between two successive, primodia., Hanstein gave the histogen concept which shows, 3 groups of initials in the shoot apex as dermatogen, (gives rise to epidermis), periblem (gives rise to, cortex), and plerome (gives rise to vascular tissue)., Schmidt proposed the TunicaCorpus concept, showing two portions in the shoot apex as tunica, (divide anticlinally) and corpus (divides anticlinally, and periclinally)., Similar to shootapex, histogen concept was also, proposed for root apex., Quiscent centre is an inactive centre in the root, apex having low DNA, RNA and proteins and it, acts as reservoirs of active initials., Calyptrogen is a distinct meristem in many, monocots that gives rise to root cap., According to KorperKappe theory the root apex, has two parts – keppe or cap and korpe or body, showing Ttype divisions., Functions of meristem are –, –, Meristem is responsible for growth or addition, of new cells in various regions of the plants., –, Stem apical tissue produces new leaves and, branches., –, Reproductive shoot apex forms flowers., –, Intercalary meristem adjusts internodal length, & protects the plants from lodging., –, Root apices continously add new structures, (root hairs) to the roots., –, Vascular cambium adds new vascular tissues, as the older ones becomes non functional., –, Cork cambium forms protective covering, around stems & roots., , PERMANENT TISSUE, l, l, , Permanent tissue are those tissue which have lost, the power of cell division., Cells of permanent tissue are matured, assume a, definite shape, size and function.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 272, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , The permanent tissues which developed from apical, meristem are called primary permanent tissue., The permanent tissues which developed from lateral, meristem are called secondary permanent tissue., On the basis of constituents cell permanent tissues, are classified into three types : simple tissues,, complex tissues and special tissues., , Simple permanent tissue, l, , l, , Simple tissue consists of a group of uniform cells, which are similar in structure and carry out same, function., Simple tissues are of three types : parenchyma,, collenchyma and sclerenchyma., , Parenchyma, l, Parenchyma is the commonest simple tissue., l, These are the most primitive tissues from which, other tissues are evolved and hence also called as, fundamental tissue., l, Parenchyma consist of oval, round, polygonal,, elongated, star shaped or irregular cells., l, Cells of parenchyma are living and arranged, loosely with intercellular spaces., l, The cells usually have thin cellulose cell walls but, parenchyma cells of secondary xylem are thick, due to the presence of lignified secondary wall., l, The parenchyma cells shows a thin layer of, cytoplasm, a peripherally located nucleus and a, large central vacuole., l, Parenchyma facilitates transfer of materials, especially solutes, by transfer cells and retention of, small quantity of food & water in all plants., l, Parenchyma cells which have large intercellular, spaces filled with air are called aerenchyma., l, Aerenchyma gives aeration and buoyancy to, aquatic plants., l, Fibre like elongated parenchyma are called, prosenchyma which provide strength and, rigidity., l, In fruits, stem tubers, tuberous roots etc.,, parenchyma store food material, so are known as, storage parenchyma., l, In succulent xerophytes like Agave, these cells store, water, so are called water storage tissue., l, Parenchyma cells of epidermis having cutinised cell, walls are protective in function and prevent, evaporation of water., l, The parenchyma cells also store waste products, , l, l, l, , like tannins, gums, resins, calcium oxalate crystal, etc., Chlorenchyma are those parenchyma cells which, contain a large number of chloroplast., Chlorenchyma are present in young stems and, leaves., Chlorenchyma carry out the process of, photosynthesis and synthesis of food materials., , Collenchyma, l, Collenchyma are living, simple, mechanical tissue., l, These are present beneath the epidermis of young, stem, petioles and midrib of leaves etc., l, Collenchyma are absent in underground tissues, and leaves & stem of monocots., l, The shape of collenchyma cell can be variable. It, may be oval or polygonal., l, Intercellular space may be present or absent., l, Cell wall of these cells are made up of cellulose, and pectin., l, Thickening of cells are confined only to the corners, of cells., l, Chloroplast is present in these cells., l, Primary pit fields are present in both parenchyma, and collenchyma., l, On the basis of thickening of the cell wall at the, corners collenchyma can be divided into three types, viz. angular, lacunar and lamellar collenchyma., l, Angular collenchyma are the most common one., Thickening is confined at the corners only, eg. stem, of Cucurbita., l, Intercellular spaces are absent in them., l, The lumen appears circular due to continued, deposition of wall materials., l, In lacunar collenchyma the thickening is confined, to the walls of the regions bordering intercellular, spaces., l, Lacunar collenchyma are present in aerial roots, of Monstera, stems of Malva etc., l, Lamellar collenchyma have thickening confined, to tangential walls, eg. stem of Clerodendron., l, Lamellar collenchyma are also called plate, collenchyma as they appear like plate or bands due, to tangential wall thickening., l, Collenchyma has various functions as, –, It provides elasticity and support to growing, organs., –, The tissue is able to grow along with the, growth of the plant organ.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňďŚŐŇť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , –, –, –, –, , The cells undergo dedifferentiation to form, phellogen., It provides support to delicate leaf margins &, prevents their tearing., The cells contain chloroplasts & perform, photosynthesis., They store small quantity of food., , Sclerenchyma, l, Sclerenchyma are simple dead mechanical tissues, occurring in mature organs of plant body., l, These are chiefly distributed in cortex, pericycle,, xylem and phloem region., l, Cells of sclerenchyma have lignified secondary cell, walls., l, Due to presence of highly thickened cell walls, the, lumen of these cells are highly reduced., l, Based on size and shape sclerenchyma cells are of, two types viz. fibres and sclereids., l, Fibres are elongated sclerenchyma cells with, pointed needle like cells., l, Fibres are longest cell in higher plants reaching a, length of 13 mm in angiosperm and 28 mm in, gymnosperms., l, Walls of fibres are lignified, hard and uniformly, thickened., l, Small round or slit like pits are present and, intercellular spaces are absent., l, The secondary walls of fibres of flax are made, up of cellulose., l, Fibres are further classified as intraxylary and, extraxylary fibres., l, Intraxylary fibres are fibres occurring in xylem., l, Libriform fibres (true fibres having simple pits), and fibre tracheids (reduced tracheids having, bordered pits) are two types of intraxylary fibres., l, Fibres occurring outside the xylem are called, extraxylary fibres., l, These are known as cortical fibres, pericyclic, fibres and phloem or bast fibre when present in, cortex, pericycle and phloem respectively., l, Sclereids are short sclerenchyma cells which are, isodiametric or irregular in shape., l, Their walls are hard, highly thickened with lignin, with simple pits., l, Sclereids are most abundant in soft tissues like, cortex, phloem, medulla, fleshy fruits, seed coats, and fruit walls., l, Sclereids are classified into the following six, , l, , l, l, l, l, l, l, l, l, l, , 273, , categories – brachysclereids, macrosclereids,, osteosclereids, astrosclereids, trichosclereids and, idioblast., Brachysclereids or stone cells are short and, isodiametric sclereids resembling parenchyma cell, in their shapes., Stone cells are found in cortex, medulla, (Nicotiana) and pulp of fleshy fruits (Annona)., Macrosclereids (also called malpighian cells) are, elongated rod like sclereids., Malpighian cells form palisade like layer in the outer, seed coat of legumes., Osteosclereids are bone like sclereids with rounded, ends found in leaves and seed coats., Astrosclereids are star shaped sclereids found in, leaves and petioles, eg. Nymphaea., Trichosclereids are elongated and hair like sclereids, found in aerial roots of Monstera and leaves of Olea., Filiform sclereids are fibre like, sparingly branched., Idioblasts are the sclereids which occur singly., The important functions of sclerenchyma are –, –, Sclerenchyma fibres provide mechanical, strength to various plant organs., –, The fibres are specialised to tolerate stress of, bending, sheering, compression and pull., –, Sclerenchyma provides for elastic stretching, and compression., –, It prevents collapsing of soft plant organs, under conditions of temporary wilting., –, Sclereids form protective covering of testa in, many legume seeds., , Complex permanent tissue, l, l, l, , A tissue made up of more than one type of cells, functioning as a unit is called complex tissue., Xylem and phloem are the complex tissues found, in all vascular plants., Xylem and phloem are together called conducting, tissues and are organised into vascular bundles., , Xylem, l, Xylem, known as water conducting tissues, is also, called hadrome (except xylem parenchyma)., l, The term xylem was coined by Nageli., l, Xylem besides conduction also provide mechanical, strength., l, Xylem increases with secondary growth., l, Xylem is of two types depending upon the time and, origin of it.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 274, , l, l, l, , l, , l, , l, l, l, l, l, l, l, l, , l, l, l, l, , l, l, l, l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Protoxylem is first formed xylem and metaxylem, is later formed xylem., Protoxylem vessels have annular or spiral, thickenings on their secondary walls., Metaxylem vessels have scalariform (like rungs, of ladder), reticulated (like net), pitted (leaving, the thin areas) thickening on their walls., Xylem may be primary (develops from, procambium) and secondary (develops from, cambium)., Xylem consists of four different types of, elements – tracheids, vessels, xylem parenchyma, and xylem fibres., A tracheid is an elongated cell with tapering ends., Their walls are highly thickened by the deposition, of lignin, except at certain points called as pits., Tracheids are dead and lignified cells., Through bordered pits movement of water and, mineral salts takes place from one cell to other., Tracheids are commonly found in pteridophytes,, gymnosperms and xylem of dicotyledons., The term tracheid was coined by Sanio., The occurrence of tracheids in the primary xylem, is considered as a primitive feature., Tracheids possess annular, spiral, scalariform,, reticulate and border pitted thickening on their, walls., Tracheids not only conduct water and dissolved, salts but also give mechanical support., Xylem vessel resembles the trachea of insect hence, it is called trachea., Vessels are present in angiosperms., Certain vesselless angiosperms are Drimys, Dagenaria. Vesselless angiosperms belong to, families winteraceae, trochodendraceae and, tetracentracae., Vessels are absent in pteridophytes &, gymnosperms., The gymnosperms like Gnetum, Ephedra,, Welwitchia contain vessels in their xylem., Lumen of the vessel is wider than that of tracheid., The vessels are made up of vessel elements., Walls of xylem vessels are lignified with annular,, spiral, reticulate, scalariform and pitted, thickening., The end walls of vessel elements are called, perforation plates., The perforation plates are of two types – simple, , l, , l, l, l, l, , l, l, l, , l, , (having one opening only) and multiple (having, several openings at the end walls) and the latter one, are of three types namely scalariform, reticulate, and foraminate., Vessels help in conduction of water and dissolved, salts from roots to the different parts of the shoot, and provides mechanical support., Parenchyma associated with xylem is called xylem, parenchyma or wood parenchyma., Primary xylem contains only axial parenchyma., Xylem parenchyma is a living component of xylem., Xylem parenchyma is made up of small thin or, thick walled parenchymatous cell having simple, pits., It helps in lateral conduction of water or sap and, stores food., Xylem fibres are sclerenchyma (dead cells) fibres, associated with xylem., Xylem fibres occur abundantly in woody, dicotyledons and add to the mechanical strength of, xylem and of the plant body., Xylem fibres are of two types – libriform fibres, (typical fibre with simple pits) and fibre tracheids., (Intermediate between fibres and tracheids having, thin walls and pits with reduced borders)., , Phloem, l, Phloem is called bast or leptome., l, Phloem is food conducting tissue (i.e. transport, food from green and storage organs of the plants, to the other organ of plant) and also provides some, mechanical support., l, First formed phloem is called protophloem and, later formed phloem is called metaphloem., l, Phloem formed from procambium is called, primary phloem and that from cambium is called, secondary phloem., l, The bulk of phloem does not increase because as, soon as new phloem becomes functional, the older, one gets crushed., l, Different kinds of elements of phloem are : sieve, elements (sieve cells and sieve tubes), companion, cells, phloem parenchyma and phloem fibres., l, Sieve cells are elongated with tapering end arranged, in parallel groups., l, These are primitive type of sieve elements., l, The perforated end walls are called sieve plates., l, A sieve plate with many sieve pores is called, compound sieve plate.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 275, , ○ňďŚŐŇť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, l, l, l, , l, , l, l, l, , l, l, l, , l, l, , l, l, , l, l, l, l, l, l, , Gymnosperms have albuminous cells and sieve, cells and pteridophytes have only sieve cells., Sieve tube consists of rows of cells arranged one, above other to form long pipes., Sieve tube occurs in angiosperms., During unfavourable conditions the cytoplasmic, strand is ensheathed by the callose material in the, sieve area and transport of food material is stopped., During favourable conditions (spring season) the, callose material dissolves and translocation of food, material is restored., Mature sieve tubes always remain closed by callose., Callose is a carbohydrate (polysaccharide), it stains, blue with aniline and forms glucose on hydrolysis., The food materials are conducted through sieve, tubes downwards from leaves to storage regions, and upwards to the growing regions, (bidirectional)., Companion cell and sieve tube are the sister cells, i.e. they are formed from the same mother cell., Companion cells are living parenchymatous cells., Companion cell contains both nucleus and, cytoplasm and show abundance of proteins. There, are cytoplasmic connections between sieve tube, and companion cell., Companion cells are present only in angiosperms, and are absent in pteridophytes & gymnosperms., The special parenchymatous cells present in the, phloem of protein rich cells are called albuminous, cells, eg. Pinus., The living parenchyma cells associated with, phloem are called phloem parenchyma., Phloem parenchyma are thin walled cells, present, in pteridophytes, gymnosperms and dicot, angiosperms except Ranunculus (monocots, generally do not have phloem parenchyma)., Only axial parenchyma is present in primary, phloem., Axial & ray parenchyma is present in secondary, phloem ., Ray parenchyma is useful for radial conduction, of food materials., Phloem parenchyma cells in general store up food, materials and help in conduction., Phloem fibres may be living or nonliving., Living phloem fibres are useful for storage of food, materials, while nonliving fibres give mechanical, strength., , Special tissues / Secretory tissues, l, , l, l, l, l, l, , l, l, l, l, , Secretory tissues are responsible for secretion of, resin, tannins, gums, alkaloids, volatile oil, nectar, latex, etc., External glands are present on epidermis., Glandular hair is found in Urtica dioca., Nectar secreting glands are present in flower parts, and leaves., Digestive glands are present in insectivorous plants., Internal glands are of many types as oil glands in, citrus, resin glands in Pinus and hydathodes in, Colocasia., Tissues which contain milky latex are called, lactiferous tissues., These tissues also contain organic substances like, alkaloid enzymes, tannins etc., Latex cells are made up of individual cells, eg., Calotropis vinea., Latex vessel are made up of number of cells joined, together, eg., Papaver., , TISSUE SYSTEM, l, , l, , l, , l, , One to many tissues performing some common, function irrespective of their position in the body, is called tissue system., According to function, tissue system are of five, types protective, mechanical, photosynthetic,, fundamental and vascular., Sachs classified the tissue systems into three types, namely epidermal tissue system, ground tissue, system and vascular tissue system., Epidermal tissue system is derived from, protoderm, ground tissue system from ground, meristem and vascular tissue system from, procambium., , Epidermal tissue system, l, l, l, , l, l, l, , Epidermal tissue system consists of epidermis and, epidermal outgrowths., Epidermis is the superficial layer covering the entire, surface of the primary plant body., Mostly epidermis is uniseriate (single layered) but, multiple epidermis is also seen in the leaves of, Nerium, Ficus sp. etc., All the epidermal cells are living (parenchymatous), and contain vacuolated protoplasms., Epidermal cells except guard cells are colourless., Large water filled epidermal cells present in the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňďŚŐŇť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , l, l, , l, l, l, l, , l, , l, , l, , l, , l, l, l, l, l, l, l, l, l, , a dead tissue called velamen tissue (multilayered, epidermis)., Epidermis consists of two types of structures , stomata and out growths (appendages)., Stomata are mostly present in epidermal layers of, leaves and in other aerial parts like young stems, floral parts etc., The specialised green epidermal cells present around, the stoma are called guard cells., Guard cells in dicots are kidney (bean) shaped and, in monocots (grasses) are dumb bell shaped., Outer wall of guard cell is thin but innerwall is thick, and inelastic., Contents of guard cell are nucleus, chloroplasts,, mitochondria, sphaerosomes, ribosomes,, endoplasmic reticulum, nucleic acids and starch., Leaves with stomata in upper epidermis are, epistomatic (eg. Nympheae), in lower epidermis is, hypostomatic (e.g. apple), on both surface is, amphistomatic (e.g. potato) and without stomata, are astomatic (e.g. potamogeton)., Stomata in which guard cells and subsidiary cells, are formed from the same mother cell are called, syndetochelic stomata., In haplochelic type of stomata guard cells and, subsidiary cells are formed from two different, mother cells., Stomata are classified into various types by various, scientists on the basis of their origin,, development, arrangement and number of the, subsidiary cells., Three dissimilar subsidiary cells are present in, anisocytic type of stomata, e.g. family Brassicaceae., The movement of stomata depends on the, turgidity and the flaccidity of guard cells., In majority of the plants stomata open during day, time and remain closed during night., Epidermal outgrowths are of two kinds , trichomes and emergences., Outgrowths formed from epidermis only are called, trichomes., Outgrowths formed from both epidermis and outer, most cortical cells are called emergences., Prickles in Rosa are emergences., Trichomes are ephemeral or persistent, their cell, wall is made up of cellulose., The trichomes are of two types glandular, (secretory) and nonglandular., , l, l, , 277, , Trichomes minimise the transpiration and give, protection to the inner parts., Root hairs do not come under the category of, trichomes, they are the tubular prolongations of, epidermal cells of root (also termed trichoblast)., , Functions of epidermis, l, Epidermis is a layer of the plant part which gives, protection to the internal tissue from mechanical, injuries, attack of pathogens and fluctuations of, temperature., l, Root epidermis helps in the absorption of water, and mineral salts., l, Having stomata epidermis helps in interchange of, gases and transpiration., l, When necessary the epidermis of the dicot stem, gives rise to cork cambium., , Ground tissue system, l, , l, l, , l, l, l, , l, , l, , l, l, , l, l, , Ground tissue system, also known as fundamental, tissues, contain various types of tissues excluding, epidermis and vascular tissues., Ground tissue system is derived partly from, periblem and partly from plerome., Ground tissue system is of two types extrastelar, ground tissue system and intrastelar ground, tissue system., Extrastelar ground tissue system is also called, cortex., Cortex is the zone which lies between the, epidermis and the pericycle., Cortex is divisible in three parts only in dicot stem, (as in the monocot stem vascular bundle are, scattered in ground tissue) and all roots from outer, to inner., Three subdivisions of cortex from outer to inner are, hypodermis, middle cortex and endodermis, respectively., The hypodermis in stems and leaves in dicot is, collenchymatous while it is sclerenchymatous in, monocots., In stems and leaves hypodermis gives mechanical, support., In dicot stem hypodermis performs photosynthesis, (when it contains chloroplasts) and gives rise to, cork cambium., Exodermis is formed in mature roots when, epidermis disorganises., Middle cortex of dicot stem is parenchymatous. It, is completely or partially chlorenchymatous.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 278, , l, , l, l, l, , l, l, , l, , l, l, l, , l, l, , l, l, l, l, l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Middle cortex in dicot stem helps in temporary, storage of food materials and sometimes, produces cork cambium or secondary meristem., Endodermis is the innermost layer of cortex., Endodermal cells are living and contain abundant, protoplasm and large nuclei., Endodermal cells of root are characterised by, casparian bands (thickening of lignin, suberin and, cutin)., Casparian bands are present on the radial and inner, tangential walls of endodermal cells., The thin walled endodermal cells present opposite, to the protoxylem are called passage cells or, transfusion cells., Endodermis acts as waterdam (water tight jacket), and prevents the movement of water from the, stele to cortex., Endodermis also acts as airdam preventing the, diffusion of air into the vessels., The layer which is useful to maintain pressure in, the root is endodermis., The innermost layer of cortex in dicot stem helps, in storage of starch materials hence called starch, sheath., The poorly developed endodermis present in the, dicot stem is called endodermoid., Pericycle, pith, medullary rays (dicot stem) and, conjunctive tissue of roots are the parts of, intrastelar ground tissue system., The pericycle of root is always parenchymatous., Pericycle is absent in the stems of monocots,, hydrophytes and parasites., Pericycle of root is the seat of origin of lateral roots, in dicots., In dicot stem the adventitious roots are formed, from parenchymatous pericycle., The central portion of the axis (dicot stem and all, roots) is called pith or medulla., Pith is mostly parenchymatous and stores water, & food materials., Parenchymatous or sclerenchymatous tissue present, between the xylem and phloem of all roots is called, conjunctive tissue., Parenchymatous extensions of pith in dicots stem, in between the vascular bundles are called, medullary rays., Medullary rays help in radial conduction of water, and food materials., , l, , Parenchyma of primary medullary ray produces the, interfascicular cambium strip. This strip joins with, intrafascicular cambium to form a vascular cambial, ring., , Vascular tissue system, l, , l, l, l, l, , l, , l, l, , l, , l, , l, , l, , l, , Central column of axis (root and stem) is called stele, which is made up of number of vascular bundles,, which constitute vascular (or fascicular) tissue, system., Each vascular bundle comprises of xylem and, phloem and cambium (if present)., Phloem elements are formed earlier than the, xylem elements., Primary phloem shows centripetal growth., Primary xylem shows 3 types of growth–, –, centripetal differentiation – protoxylem, towards outside is called exarch., –, centrifugal differentiation – protoxylem, facing the centre is called endarch., –, centripetal as well as centrifugal, differentiation – protoxylem surrounded by, metaxylem is called mesarch., Depending upon the number of protoxylem group,, root can be differentiated as monarch (single, protoxylem group), diarch, triarch, tetrarch,, pentarch, hexarch, polyarch (more than 6, protoxylem group)., The dicot root show mono to hexarch condition, whereas monocot root are hexarch to polyarch., Exarch xylem is seen in all roots, mesarch in rachis, and leaflets of Cycas and endarch in stems of, angiosperms and gymnosperms., Usually procambium towards outside, differentiates into phloem and the procambium, present inside differentiates into xylem., Undifferentiated procambium present between, primary phloem and primary xylem is called, intrafascicular cambium or fascicular cambium., A special conducting tissue present in addition to, primary phloem and primary xylem in the leaves of, gymnosperms (Cycas, Pinus) is called transfusion, tissue., Depending on the arrangement of phloem &, xylem, vascular bundles are of four kinds , collateral, bicollateral, concentric and radial, (separate)., When the phloem and xylem are present side by
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňďŚŐŇť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , l, l, l, , l, l, l, l, , l, l, , l, , l, , l, , l, , l, l, , l, l, l, , l, , side on the same radius, the vascular bundles are, called collateral vascular bundles., Collateral vascular bundles are present in stems and, leaves of angiosperms and gymnosperms., If cambium is present in a collateral bundle then, it is called open vascular bundle., If cambium is absent between phloem and xylem, then the vascular bundle is called closed vascular, bundle., Open vascular bundles are present in the stems of, dicots and gymnosperms., Closed vascular bundles are present in stems of, monocots (also in leaves)., A vascular bundle containing phloem on either side, of xylem is called bicollateral vascular bundle., Bicollateral vascular bundle consists of outer, phloem, outer cambium, xylem, inner cambium, and inner phloem, e.g. cucurbitaceae and, solanaceae (stems)., Collateral bundles of stems and bicollateral bundles, show endarch xylem., Collateral and bicollateral vascular bundles are, conjoint vascular bundles (vascular tissues are, arranged on the same radius)., When one type of vascular tissue is surrounded by, another type, the vascular bundle is called, concentric vascular bundle., Concentric vascular bundles are of two types, amphicribal (or hadrocentric) and amphivasal (or, leptocentric)., When xylem is surrounded by phloem, such, concentric vascular bundles are called amphicribal, or hadrocentric, eg ferns., When phloem is surrounded by xylem the vascular, bundle is called amphivasal or leptocentric, eg, Dracaena., Concentric vascular bundles are of closed type., When xylem and phloem are arranged alternately, on different radii the vascular bundles are called, radial and separate vascular bundles., Radial vascular bundles are always closed and, present in all roots., Stele in which pith is absent is called protostele,, e.g Selaginella, Lycopodium., A medullated stele having cylindrically arranged, vascular tissues, is called siphonostele, e.g., Marsilea (stele with pith)., Highly dissected stele is called dictyostele., , l, l, l, l, , 279, , A branch of dictyostele is called meristele, e.g. ferns, (Adiantum)., Stele with circular arrangement of vascular, bundles is called eustele, e.g. dicot stem., Stele containing irregularly scattered vascular, bundles is called atactostele, e.g. monocot stem., First plants possessing stele are pteridophytes., , ANATOMY OF DICOT AND MONOCOT, PLANTS, Anatomy of dicot root, l, , l, l, l, l, , l, l, l, , l, l, l, , Dicot root consists of a single layer of epiblema, or piliferous cells which bears unicellular root, hairs., Cuticle or stomata is absent in root., Endodermis is made up of single layer of barrel, shaped cells without intercellular spaces., Casparian strips are present along the tangential, and radial walls of endodermis., Endodermis is followed by one (sunflower) or more, (mulberry) layers of pericycles. Pericycle is absent, in the roots of some aquatic plants and parasites., A part of vascular cambium is formed from, pericycle., Inner to pericycle lies radially arranged vascular, bundles (2 6)., Radial arrangement of vascular bundles is a, mechanism to keep the xylem bundles in direct, contact with the outer tissues of the root which, conduct water absorbed by root hairs to the inside., Xylem is exarch., Conjuctive tissue is present which later becomes, meristematic to form vascular cambium., Generally pith is absent in root or if present is very, small., , Anatomy of monocot root, l, l, , l, l, , l, , Monocot root is similar to dicot roots in having, epiblema, cortex, endodermis and vascular tissues., The number of radial vascular bundles are more, than in dicot roots. Eg. 2030 in maize and 100 or, more in Pandanus and palms., Xylem is exarch and polyarch., The conjuctive tissue present in between xylem and, phloem, store food and provide mechanical, strength but do not form cambium., The centre of the monocot root is occupied by large, pith.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 280, , ŕďőĽę– ĐĽŐńŐĹť, , Anatomy of dicot stem, l, , l, l, l, l, l, , l, l, l, l, l, l, l, , Epidermis of dicot stem is made up of compactly, arranged elongated parenchymatous cells, having, distinct cuticle, stomata and trichomes (sunflower)., Inner to epidermis is present 34 layers of, collenchymatous hypodermis., Inner to hypodermis is cortex., In sunflower cortex contains oil ducts., Endodermis lies at the innermost boundary of, cortex. Casparian strips are absent in stem., Inner to endodermis is present a few layers of, heterogenous pericycle (parenchyma and, sclerenchyma)., Bundle caps are sclerenchymatous pericycle., Eustelic type of vascular bundle (VBs arranged, in ring, also present in gymnosperms) is seen here., Vascular bundles are conjoint, collateral and open., Cambium helps in secondary growth., Xylem is endarch and fascicular cambium is, present., Medullary rays are present in between vascular, bundles., The central portion is occupied by pith., , l, , l, , l, l, l, l, , Anatomy of monocot leaf (isobilateral), l, l, l, l, , Anatomy of monocot stem, l, , l, l, l, , Monocot stem is characterised by epidermis,, (2 3 layered) hypodermis and undifferentiated, ground tissue stem., Vascular strand is atactostele (numerous and, scattered)., Vascular bundles are conjoint, collateral and, closed. Phloem lies on outer side., Xylem is endarch., , Anatomy of dicot leaf (dorsiventral), l, , l, , l, l, l, l, , Dicot leaf is characterised by upper and lower, epidermis, cuticle, mesophyll cells and vascular, bundles., Epidermis is generally single layered (multilayered, in Ficus) with cuticle and stomata in only lower, epidermis (in upper epidermis only in floating, leaves)., Epidermal cells may have some outgrowth called, papillae, eg. Gladiolus., Mesophyll is present in between upper and lower, epidermis., Mesophyll are of two types palisade parenchyma, and spongy parenchyma., Palisade parenchyma are made up of elongated,, , columnar cells without intercellular spaces, have, chloroplast., Spongy parenchyma made up of oval or spherical, cells with intercellular spaces is present below, palisade parenchyma., Vascular bundles (VBs) are scattered in spongy, parenchyma and the vascular bundle in midrib, region is largest., VBs are conjoint, collateral and closed., Each vascular bundle is surrounded by a bundle, sheath of parenchymatous cells., Xylem is present towards the upper epidermis and, phloem towards the lower epidermis., Above and below the largest vascular bundle are, present parenchymatous or collenchymatous mass, of cells, devoid of chloroplast., , l, , l, , Isobilateral leaf is somewhat similar to dorsiventral, leaf having epidermis, cuticle and mesophyll cells., Stomata are present on both the surfaces of, epidermis., Bulliform cells or motor cells are present., Mesophyll cells are undifferentiated into palisade, and spongy parenchyma., Vascular bundles are conjoint, collateral, closed, with phloem towards lower side and xylem, towards upper side., Above and below larger vascular bundles are present, patches of sclerenchymatous cells., , SECONDARY GROWTH, l, l, , l, l, , l, l, , The formation of secondary tissue which leads to, increase in girth is called secondary growth., Secondary tissues are formed by two types of, lateral meristems vascular cambium (formed, from conjunctive parenchyma and pericycle) and, cork cambium or phellogen (formed from, pericycle)., Vascular cambium produces secondary vascular, tissues., Cork cambium or phellogen produces phellem, (cork cells) on the outer side and phelloderm on, the inner side., Phellem, phellogen and phelloderm together, constitutes the periderm., The fascicular cambium and the interfascicular, cambium together constitutes the vascular, cambium.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňďŚŐŇť– Őě– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, l, , l, l, l, l, l, l, l, l, l, l, , l, , l, , The cambial ring cuts of secondary xylem towards the, centre and secondary phloem towards the periphery., Secondary xylem consists of vessels, xylem, parenchyma and few fibres and secondary phloem, consists of sieve tubes, companion cells, phloem, parenchyma and fibres., Amount of secondary xylem is more than, secondary phloem and so stem increases in girth., Cambial cells are of two types – fusiform initials, and ray initials., Fusiform initials give rise to vessels and tracheids., Ray initials give rise to rays in secondary tissue., The wood formed in a single year is called annual, ring., Spring wood is the secondary xylem formed, during spring when the cambial activity is more., Wood elements are larger in size and have wider, lumen., Autumn wood (or late wood) is the wood element, formed during winter when cambial activity is less., Wood formed is lesser in amount and have narrow, lumen., The age of tree can be determined by counting, annual rings, the process is known as, dendrochronology., In perennial woody trees, the central portion is, dark, hard and tough due to deposition of resins,, tannins, gums and formation of tyloses., This region consists of dead elements and do not, conduct water but provides mechanical support., , l, l, l, l, , l, , l, , l, l, l, , l, l, l, , l, , 281, , This central region is called heartwood (duramen)., The outer or peripheral portion is soft and lighter, in colour consisting of living cells., It is called sap wood (alburnum) and helps in, conduction of water and minerals., Wood of gymnosperm is called nonporous or soft, wood (absence of vessels and fibres) and that of, dicots is called porous or hard wood., Porous wood may be ring porous (large size vessel, in early wood) or diffuse porous (vessels, throughout)., Tyloses are balloon like structures, produced due, to ingrowth of xylem parenchyma into the lumen, of xylem vessels through pits., Bark is all the tissues outside vascular cambium., All the dead cells outside the innermost layer of cork, cambium constitute rhytidome., There are certain loosely arranged areas in the, periderm formed due to rapid activity of phellogen,, called lenticels., Lenticels help in gaseous exchange and, transpiration., In dicot root, vascular cambium is completely, secondary in origin., Secondary growth takes place by extra stellar, cambium which cuts phellem and phelloderm as in, stems., Abnormal type of secondary growth or increase, in thickness are found in some arborescent, monocots like Dracaena, Yucca, Agave, etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 282, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 31, , Animal Tissue, l, l, l, , Tissue means similar cells having common origin, and functions., Cells of a tissue are often held together by cell, junctions., The word tissue was used by Bichat (1972) and, histology by Mayer (1819)., , l, l, l, , The study of microscopic structures of tissues and, organs are called histology., Marcello Malpighii is regarded as father of animal, histology., The formation of tissues from germinal layers is, called histogenesis., , Table : Types of animal tissues according to their origin and functions., Type, , Origin, , Epithelial tissue, Connective tissue, , Ectoderm (skin epidermis); endoderm (gut, epithelium); mesoderm (coelomic epithelium), Mesoderm, , Muscular tissue, , Mesoderm, , Nervous tissue, , Ectoderm, , EPITHELIAL TISSUE, l, , l, l, , l, , l, l, , Function, , Epithelial tissue (the first tissue to be formed) is, arranged in single or multilayered sheets and covers, the internal and external surface of the body of, an organism., The cells in epithelial tissues are very closely packed, together and joined with little space between them., Origin of epithelial tissue is ectoderm (skin, epidermis), endodermis (gut epithelium), and, mesoderm (coelomic epithelium)., Epithelial tissue helps in protection, secretion,, absorption, excretion, transcellular transport,, sensation detection, selective permeablity and, reproduction., The term ‘epithelium’ was coined by “Ruysch”., Epithelium is subjected to wear, tear and injury,, its cells divides and produce new cells to replace, those that are destroyed., , l, , l, , l, , Protection, secretion, absorption,, excretion, reproduction, Attachment, support, storage,, protection & transport, Movement of body parts &, locomotion and support, Control and coordination by, nerve impulse., , Epithelium is polarized i.e., it has a free surface, (the apical surface) exposed to outside and an, attached surface (the basal surface) resting on the, underlying connective tissue., Depending on the nature, epithelial tissue can be, classified as – (i) covering and lining epithelium, or true epithelium, and (ii) glandular epithelium., True epithelium can be classified into simple and, compound epithelium., True epithelium, Simple, (one cell thick), , Compound, (more than one, cell thick), , Squamous, Cuboidal (cubical), Columnar, Ciliated, Pseudostratified, , Stratified, Transitional
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ♀ĽřřśĚ–, l, , l, l, , l, , Common structures present in epithelial membrane, are intercellular junctions (which provide, structural integrity of the epithelium), basement, membrane and structures on the free surfaces of, cells like microvilli, stereocilia, cilia, flagella and, endocytic, exocytic and pinocytic vesicles., The bottom layer cells rest on a basement membrane., Basement membrane is composed of a network, of fibres which include collagen (in a matrix) and, proteoglycans and serves a selective filter, determining which molecule diffuse from the, undergoing connective tissue., Glandular epithelium are invaginated epithelia, into the connective tissue which differentiate into, secretory units. It can be classified on the basis of, their features., , l, , l, , l, , l, l, , Glandular epithelium, Division according to, Presence or, absence, of ducts, , Mode, of secretion, Holocrine, , Exocrine Endocrine, (With, (Without, ducts), ducts), Number of cells, , Unicellular Multicellular, (One celled) (Many celled), , l, , Apocrine, , l, , Merocrine, Nature of secretion, , Serous, , Mixed, , Depending on the shape of secretory units, Alveolar, Tubular, Tubuloalveolar, (saccular), Simple, Simple, Simple branched, Simple branched, Simple compound, Simple compound, l, , l, l, l, , l, , Epithelium lining the lumen of blood vessels is, called endothelium and lining the body cavity, mesothelium., Epithelial cells are not supplied with blood vessels., Nerve ending may occur in epithelium., Cilia are fine fibres having 9+2 internal structure., They are also known as kinocilia. They are motile,, occur in cells of respiratory and reproductive tract., Stereocilia are nonmotile and cylindrical. They, are found in epididymis, vas deferens and organ, of corti., , l, l, l, , l, , l, , l, , l, l, , 283, , Cilia is associated with flow of materials in a, particular direction, stereocilia (long microvilli) is, associated with the movement of sperms and, microvilli increase the absorptive area where they, are present., In simple epithelium, cells are single layered, thin, and flattened and all have direct contact with, basement membrane., Squamous epithelium is also called pavement, epithelium because the cells look like tiles of floor., It occurs in renal capsules of kidney, alveoli of, lungs, wall of blood capillary and heart, lining of, eye etc., The one cell of simple squamous epithelium is a, minimal barrier to diffusion., Cuboidal epithelium is the least specialized of all, epithelia having roughly cubeshaped cells with, centrally placed nucleus. It is often with microvilli, hence, called brush bordered cuboidal, epithelium., Cuboidal epithelium is found in surface of ovary,, kidney tubules etc., Cells of columnar epithelium are tall and quite, narrow, thus providing more cytoplasm per unit, area of epithelium., Nucleus is present at the basal end in columnar, epithelium., Columnar epithelium is ciliated in bronchioles and, fallopian tube., Columnar epithelium is secretary in nature in, gastric glands of stomach, intestinal glands,, pancreatic lobules and gall bladder., Sensory epithelium (modified columnar cells) bear, sensory hairs on their free surface and are connected, with nerve fibres. These are found in retina, nasal, cavity (Schneiderian membrane) and tongue, (gustatory cells), brain etc., In pseudostratified epithelium, a single layer of, cells is present but they are all at different levels, thus appearing multilayered., Pseudostratified epithelium is found lining the, urinary tract and the respiratory passages, (trachea, bronchi, bronchioles)., Compound (stratified) epithelium is made of, more than one layer (multilayered) of cells., Stratified epithelium is thicker than simple epithe, lium and forms a relatively tough impervious, barrier.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 284, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Summary chart of epithelial tissues., Location, , Structure, , Function, , Simple Squamous, Single layer of flat scalelike cells, large Alveoli, Bowman’s capsule, blood vessel, (endothelium) heart, visceral and peritoneal, centrally located nucleus., lining of coelom (mesothelium), , Filtration, absorption, and secretion, , Simple Cuboidal, Single layer of cubeshaped cells, centrally Surface of ovary, inner surface of cornea, and lens of eye, kidney tubules, salivary, located nucleus, and pancreatic ducts and thyroid vesicles, , Secretion and, absorption, , Simple Columnar (Nonciliated), Single layer of nonciliated rectangular Lines stomach, small and large intestine,, cells, contains goblet cells, nuclei at bases digestive glands and gallbladder, of cells, , Secretion and, absorption, , Simple Columnar (Ciliated), Single layer of ciliated rectangular cells, Oviduct, fallopian tube, neurocoel of CNS,, contain goblet cells, nuclei at bases of cells few portions of upper respiratory tract, Stratified Squamous, Nonkeratinizing, Several layers of cells, deep layers are Mouth, oesophagus, part of epiglottis and, cuboidal to columnar, surface layers flat vagina, and scalelike, Keratinizing, Dry surface of skin, , Movement of gametes,, cerebrospinal fluid and, mucus by ciliary action, Protection, , Stratified Cuboidal, Two or more layers of cubeshaped cells Duct of adult sweat gland, , Protection, , Stratified Columnar, Several layers of polyhedral cells, only Male urethra (only part), superficial layer is columnar, , Protection and, secretion, , Transitional, Resembles stratified squamous nonkera Urinary bladder and ureters, tinizing tissue, except superficial cells are, larger and more rounded, Pseudostratified, Basically it is single layered, but few basal Trachea, bronchi, olfactory epithelium,, cells are present, smaller in size and do eustachian tube, not reach upto free surface., l, , l, , The first formed cells are cuboid in shape, but as, they pushed outwards towards the free surface of, the tissue, they become flattened. In this condition, the cells are called squamous., Stratified squamous epithelium may be, keratinized (epithelium of skin, hard palate,, , l, , Permits distention, , Secretion and, movement of mucus, by ciliary action, , gingiva) and nonkeratinized (buccal cavity,, pharynx, oesophagous etc)., Keratinized epithelium contains keratin a highly, insoluble fibrous protein with water proofing, qualities and is also resistance to friction and, bacterial invasion.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 285, , ○ňĽŇďń– ♀ĽřřśĚ–, l, , l, l, l, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , Nonkeratinized epithelium is found on wet, surface that are subjected to considerable wear, and tear and do not perform the function of, absorption., Transitional epithelium is often regarded as a, modified type of stratified epithelium., No basement membrane is present in transitional, epithelium as it would impede stretchabilitiy., Transitional epithelium lines the inner surface of, renal calyces, urinary bladder, ureter. Because, of its distribution, it is also called urothelium., Since the cells in transitional epithelium, can slide, over each other, the appearence of this epithelium, depends on whether the organ is distended or, contracted, if distended it appears as if there are, only a few layers and when contracted, it appears, as if there are several layers., Endocrine glands (ductless) manufactures, hormones and secretes them directly into the, bloodstream to act at distant sites in the body, (known as target organs or cells), e.g., pituitary,, thyroid etc., Exocrine glands pour their secretion through ducts, at the site of action, e.g., salivary gland, gastric, gland etc., Goblet cell, found in the lining of respiratory tract, and alimemtary canal, secrete mucous and is the, example of unicellular gland., Sweat glands, intestinal glands, crypts of Liberkuhn, are simple tubular gland. The gland is elongated, and tube like., Gastric glands, Brunner’s glands, Bartholin’s glands, are simple branched tubular. It has simple duct, with branched tubes., Bulbourethral gland and liver are compound, tubular. Duct is branched aggregation of tubules., Mucous and poison gland in amphibian skin are, simple (acinar) alveolar. This gland has single, flask shaped duct with sac., Sebaceous, meibomian glands are simple branched, alveolar. Duct branched but with many sac (flasked, shaped)., Salivary glands like submandibular and, sublingual glands are compound alveolar glands, whose secretory portion is flask shaped., Mammary glands, pancreas, lacrimal gland are, compound tubuloalveolar.In them tube ends in, a sac like dilation., , l, , l, , l, , In apocrine glands apical portion (where secretory, products accumulates) of cell goes with secretion,, example mammary glands., In holocrine glands secretory cell comes out with, the secretion, example sebaceous glands., Sometimes holocrine glands are described as, those endocrine glands which secrete, only hormones. Example Thyroid, PTH, adrenals, etc., In merocrine glands only secretion is secreted, without any loss of cells or their parts. Example , most of the glands such as salivary glands, sweat, glands etc., , CONNECTIVE TISSUE, l, l, l, , l, , l, , l, , l, l, , Connective tissue is the major supporting tissue, of the body., About 30% of body mass is formed of connective, tissue., Connective tissue fulfils many functions other than, packing and binding other structures together, such as, –, providing protection against wounding or, bacterial invasion (areolar tissue),, –, insulation of the body against heat loss, (adipose tissue),, –, providing a supportive frame work for the, body (cartilage and bone) which plays an, important role in locomotion, and keeps all, the organs avoiding ptosis (prolapse of an, organ or part); and, –, producing blood cells., Connective tissue is divided into three categories, connective tissue proper (including matrix, cells, and protein fibres), skeletal tissue (containing, cartilage and bone) which plays an important role, in locomotion and vascular tissue (including blood, and lymph)., Connective tissue proper is a composite material, made up of a variety of cells. It contains several, types of fibre which are nonliving products of, the cells and a fluid or semifluid background, material or matrix in between the cells., The cells of connective tissue are living and, responsible for secreting the large amounts of, intercellular ground substance (matrix)., Ground substance or matrix occupies the space, between the cells and fibres of connective tissues., Matrix consists of mainly water and sulfated, mucopolysaccharide.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 286, , ŕďőĽę– ĐĽŐńŐĹť, CONNECTIVE TISSUE, Connective tissue, proper, , Ground substance Tissue, (matrix), cells, , Vascular, tissue, , Blood, , Protein, fibres, , Plasma, , Collagen Elastic Reticular, fibres, fibres, fibres, Fibroblast, Mast cells, Plasma cells, Macrophages, Lymphocytes, , Skeletal, tissue, Bone, , Cartilage, , Cellular, elements, , Lymph, Includes, Leucocyte, Plasma, , Red blood White blood, cells, cell, (carries, (functions, oxygen with in defence, the help of mechanisms), haemoglobin), , Platelets, (help in, blood, clotting), , Cells, Hyaline Elastic Fibrous Types, cartilage cartilage cartilage, Osteoblast Osteocytes Osteoclast, Spongy, (contain red, bone marrow), , l, , l, , l, , l, l, , The matrix is a non living material which may be, liquid (e.g. blood), semisolid (e.g. connective, tissue) or solid (e.g. bone)., Types of connective tissue cells are , –, fibroblasts secreting fibres and some matrix., –, macrophages (histiocyte) which are modified, monocytes cells and having the capacity to, phagocytose., –, mast cells storing histamine (vasodilator),, serotonin (vasoconstrictor) and heparin, (anticoagulant)., –, lymphocytes which are migrating cells and, transport antibodies., –, plasma cell producing antibodies., Connective tissue is composed of several protein, fibres such as collagen fibres (having protein, collagen), elastic fibres (having protein elastin), and reticular fibres (having protein reticulin)., Collagen is the most abundant protein in the, human body., Disease caused by abnormal collagen structure, are –, –, Marfan’s syndrome (causing abnormal, fibrillin and results in abnormally long and, distensible extremities etc.);, , Compact, (contain, yellow bone marrow), , –, , l, , l, , l, l, , l, , l, l, , Scurvy (due to vitamin C deficiency as vitamin, C is required for collagen cross linking), and, –, Ehlers Danlos syndrome (causing, progressive deterioration of collagen)., Elastic fibres are prominent in parts of the body, that expand and contract regularly like blood vessel, walls., On the basis of cells and fibres present connective, tissue proper is further divided into – areolar tissue,, adipose tissue, dense connective tissue (fibrous, and elastic), reticular connective tissue, mucous, and pigmented connective tissue., Loose or areolar connective tissue has abundant, matrix, thin and sparse fibres and almost all cell types., Found beneath the epithelia, hollow visceral organs, and on the walls of arteries and veins, areolar tissue, helps in packing, protecting, nourishing etc. It is, also important in inflammation., Adipose tissue contain adipocytes, used for, cushioning, insulation, lubrication (primarily in, the pericardium) and energy storage., Adipose tissue are found beneath the skin in, mesentries, bone marrow, kidney, liver etc., White fat and brown fat are two types of adipose, tissue.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ♀ĽřřśĚ–, l, , l, , l, l, , l, , l, , l, l, , l, , l, , l, , l, , l, l, , l, l, , White fat contains primarily unilocular, adipocytes (one large fat vacuole) and brown fat, contains multilocular adipocytes (many small fat, vacuoles)., Brown fat (whose brown colour is due to iron, containing cytochrome pigments in fats) is found, in hibernating animals such as rats and also in, new born babies., Adipose tissue is a poor conductor of heat, it, reduces heat loss through skin., Prominent adipose tissue sites are – subcutaneous, fat (panniculus adiposes), blubber of whales,, humps of camel., In white fibrous tissue, collagen is dominant and, cells are mainly fibroblasts. It makes the joints, immovable., Fibroblast facilitate wound healing by filling the, gaps in the tissue by proliferating and migrating, towards the wound. Fibroblasts form the scar that, closes the wound., White fibrous tissue is found in skull bones and, dermis of higher mammals., A tendon, which connects skeletal muscle to a bone, is a modification of white fibrous tissue. It is, being tough and inelastic., Yellow elastic tissue is mainly composed of elastic, fibres. They are mostly present in ligaments, wall, of blood vessels, bronchioles and lung., Ligaments attach one bone to another. They contain, both collagen and the protein elastin (which permits, ligaments to be stretched)., Reticular connective tissue is a network of reticular, fibres (fine collagen with a rich coat of, glycoproteins) that form a soft skeleton to support, the lymphoid organs (lymph nodes, bone marrow, and spleen)., Mucous connective tissue is composed of a, gelatinous substance (called Wharton’s jelly), few, fibroblasts and collagen., It is found in vitreous humor and umbilical cord., Cartilage and bone are specialized connective, skeletal tissues that provide the body with, mechanical support and protection., Cartilage is usually found in close association with, bone in the body., Cartilage is composed of cells called chondrocytes, which are dispersed in a firm gel like ground, substance called matrix., , l, l, , l, , l, , l, , l, , l, l, , l, l, , l, , l, , l, l, , l, , l, l, l, , 287, , Chondrocytes lie in a cavity called a lacuna., Cartilage is avascular (contains no blood, vessels) and nutrients are diffused through the, matrix., The matrix of cartilage consists mainly of, glycoprotein material, chondroitin sulfate and, keratan sulfate., Cartilage is found in the joints, ribcage, the ear,, the nose, in the throat and between intervertebral, discs., The cartilage in the ear and nose do begin to grow, with age as the production of sex hormones, lowers., The margin of a piece of cartilage is enclosed by, a dense layer of cells and fibrils known as, perichondrium., There are three main types of cartilage – hyaline,, elastic and fibrocartilage., Hyaline (means glassy or shiny) cartilage is an, elastic, compressible tissue located at the ends of, bones, on nose, bronchi, larynx etc., Inside the bone, hyaline cartilage serving as a, centre of ossification or bone growth., C shaped rings of hyaline cartilage keep open the, air passages of the respiratory system (trachea,, bronchi and larger bronchioles)., Hyaline cartilage also forms the skeleton of, cartilaginous fish (e.g. shark) and forms the, embryonic skeleton in bony vertebrates., Calcified cartilage is formed by the calcification, of hyaline cartilage. It is found in suprascapula, and pubis in frog., Yellow elastic cartilage is found in external ear, and epiglottis., Elastic cartilage helps to maintain the shape and, flexibility of the organ and also strengthens and, supports these structures., Fibrous (also called white cartilage) cartilage is, the strongest cartilage due to presence of collagen, fibres., It occurs in the pubic symphysis of man and, intervertebral disc., Fibrocartilage lacks a perichondrium., The matrix of cartilage acts as a barrier, preventing, the entry of lymphocytes or diffusion of, immunoglobulins. This property allows for the, transplantation of cartilage from one individual to, another without fear of tissue rejection.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 288, , l, l, , l, , l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Cartilage cells can give rise to benign (chondroma), or malignant (chondrosarcoma) tumors., Bone, also called osseous tissue, is a type of hard, endoskeletal connective tissue found in many, vertebrate animals., Bone supports body structures, protect internal, organs, and (in conjuction with muscles) facilitate, movement; and are also involved with cell, formation, calcium metabolism and mineral, storage., Osteoblasts form bones and its formation is called, osteogenesis., About 30% of bone matrix is composed of organic, material (ossein protein), whilst 70% is inorganic, bone salts [such as hydroxyapatite,, Ca10(PO4)6(OH)2, a form of calcium phosphate]., Sodium, magnesium, potassium, chloride, fluoride,, hydrogen carbonate and citrate ions are also present., Bone resorption and reconstruction processes, enable a particular bone to adapt its structure to, meet any change in the mechanical requirement of, the animal during its development., Calcium and phosphate may be released into, the blood as needed, under the control of two, hormones parathormone and calcitonin., Bone is surrounded by a sheath of collagen fibres,, periosteum which is richly supplied with blood, vessel, whereas the bone marrow cavity is, surrounded by endosteum., A compact mammalian bone has several concentric, lamellae through which blood vessels, lymphatics, and nerves pass, this is called haversian canal., Main function of haversian canal is transportation, of nutrients and oxygen through blood., Haversial canals run parallel to the marrow cavity, and contain all the structures similar to marrow, cavity except the lymph vessels which are absent., In the solid matrix of bone, flat irregular space,, lacunae are present in which a single osteocytes, (inactive bone cells) is present., Radiating from each lacuna are many fine channels, called canaliculi containing cytoplasm which may, link up with the central Haversian canal with other, lacunae or pass from one lamelle to other., Bone cells are of three kinds osteoblasts (bone, forming cells), osteocytes (bone maintaining cells), and osteoclasts (bone cleaning cells)., Osteoblasts are located near to the surface of bone, , l, l, l, , l, l, l, l, , l, l, , l, , l, , l, , l, l, l, l, l, l, l, , and their functions are to make osteoid and, manufacture hormones such as prostaglandin which, act on bone itself., Osteoblasts secrete bone extracellular matrix., When an osteoblast is completely surrounded by, matrix, it is called osteocyte., Osteocytes respond to parathormone to help, regulate blood calcium and can secrete new bone, extracellular matrix., Osteoclasts are syncytial cells and formed by the, fusion of monocytes and destroy bone matrix., Osteoclasts release lysosomes, organic acids and, hydrolytic enzymes to break down bone matrix., Osteoclast respond to parathormone and calcitonin, to help regulate serum calcium levels., Bone marrow cavity is filled with a soft and, sinusoidal fatty neurovascular tissue, called bone, marrow., Bone marrow will indicate blood related diseases, like leukemia., Bone marrow contains two types of stem cells –, haemopoietic (which can produce blood cells) and, stromal (which can produce fat, cartilage and bone)., Haematopoietic stem cells give rise to the three, classes of blood cell that are found in the circulation, leucocyte, red blood cells (erythrocytes) and, platelets (thrombocytes)., The tissue of bone marrow where pluripotential, haemopoietic stem cells form is called myeloid, tissue., Stromal stem cells have the capability to, differentiate into many kinds of tissues, such as, nervous tissue., Bone marrow has haematogenic and osteogenic, potentials., Bone marrow are of two types red bone marrow, and yellow bone marrow., Red bone marrow are active vascular tissue in, the long bone and produces red blood cells., During foetal life and at birth red bone marrow, occurs throughout the skeleton., Yellow bone marrow are inactive vascular tissue, in the long bones., Yellow colour is due to predominance of, adipocytes., At birth, all bone marrow cavities are, haematopoiesis. As the individual ages, the loci, of haematopoiesis shift.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 289, , ○ňĽŇďń– ♀ĽřřśĚ–, l, , l, l, l, , l, l, , l, , l, l, , l, , l, l, l, l, , l, l, l, , l, , Spongy bone (also known as cancellous bone), carries no haversian system and consists of a, meshwork of thin, interconnecting bony struts called, trabeculae., The space in between the trabeculae contain red, bone marrow., Spongy bone occurs in the embryo, growing, organisms, and the swollen ends of long bones., The matrix of spongy bone contains a rather, smaller proportion of inorganic material than, does the matrix of compact bone., Compact bone form shaft (diaphysis) of long bones, and consists of yellow bone marrow., Foetal sites of haematopoiesis are blood islands, (group of mesenchymal cells in the yolk sac), liver,, spleen and bone marrow., Dried bone is a bone without living cells. Dried, bone possesses matrix, lacunae, canaliculi, marrow, cavity etc., Cartilage bone is formed by ossification of, cartilage. It is also known as replacing bones., Investing bone is formed by transformation of, connective tissue. It is also known as membrane, bone., Visceral bone (heterotypic bone) is a bone, separated from the remaining skeleton, e.g. os, cordis (interventricular septum of heart in deer),, os penis (penis in rodents, bats etc), os palpebrae, (eye lids of crocodile) etc., Sesamoid bone is a bone formed within a tendon, near a joint., Dibolic bone is bone with compact surfaces and, cancellous middle, e.g. skull bone, vertebrae., Bone can also be either woven or lamellar., Woven bone is put down rapidly during growth or, repair. It is so called because its fibres are aligned, at random and as a result has low strength., Lamellar bone has parallel fibres and is much, stronger., Woven bone is often replaced by lamellar bone, as growth continues., Blood (derived from mesoderm) is a highly, specialised fluid connective tissue constituting, approximately 8% of the body weight or 5.6 1ts in, a 70 kg man., Blood consists of the plasma, a pale yellow liquid, containing the microscopically visible formed, elements of the blood: the erythrocytes, (or red, , l, , l, , l, l, , l, l, , l, l, , l, , l, , l, , blood corpuscles); the leucocytes, (or white blood, corpuscles); and the platelets, (or thrombocytes)., Plasma is the relatively clear liquid protein, slightly, alkaline (pH–7.4) and salt solution which carries, the red cells, white cells, and platelets., Red cells (or erythrocytes) are relatively large, microscopic cells without nuclei. In this latter, trait, they are similar to the primitive prokaryotic, cells of bacteria., Haemoglobin is the gas transporting protein, molecule that makes up 95% of a red cell., In mammals (except camel and Llama), red blood, cells are nonnucleated biconcave and circular. The, total count of RBC (number of erythrocytes per, microlitre of 1 mm3 of blood) is 5 millions and 4.5, million in adult man and woman respectively., The mature RBC lacks all organelles and almost, entire volume of the cell is filled with haemoglobin., White blood cells (also called leucocytes or, immune cells) help to defend the body against, infectious disease and foreign materials as part of, the immune system., There are two major types of white blood cells:, granulocytes and agranulocyte., Granulocytes are characterised by the fact that all, types have differently staining granules in their, cytoplasm on light microscopy. There are three, types of granulocytes: neutrophils, basophils, and, eosinophils (named according to their staining, properties)., Agranulocytes are not found in the cytoplasm. They, are formed in spleen and lymph nodes. They are, of two types lymphocyte and monocytes., Platelets are nonnucleated round or oval biconvex, disc like bodies. They bud off from the cytoplasm, of very large megakaryocyte cells of bone marrow., Blood platelets help in coagulation of blood by, producing platelet factors, (such as, thromboplastin)., [Note : For more on blood refer chapter Body fluids, and circulation.], , MUSCULAR TISSUE, l, l, , Muscle is a contractile tissue that both generates, and transmits force., Muscular tissue is responsible for the movement, of the body and for the movement of its various, parts with respect to one another.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 290, , l, , l, , l, , l, , l, l, l, l, , l, l, l, , l, l, , l, , l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , It is made up of long, excitable cells or muscle, fibres containing sarcomeres (composed of actin, and myosin), and devoid of matrix., Myoblast (spindle shaped muscle precursor cells), give rise to muscle fibre and each fibre consists of, fine fibrils present in the cytoplasm (known as, sarcoplasm)., Muscular tissue carries out mechanical work by, contracting, which involves a shortening and, thickening of its fibres., Two proteins, actin and myosin are part of the, machinery and ATP is the immediate energy, source for the contraction., Muscular tissue is derived from the mesodermal, layer of embryonic germ cells., These are arranged in a parallel pattern within, the cytoplasm of muscle cell., The membrane of a single muscle fibre is known, as sarcolemma., Each muscle fibre contains proteinaceous fibrils,, known as myofibrils which can be seen by both, light and electron microscopy., Connective tissue over a single muscle fibre is, known as endomysium., Perimysium is a fibrous sheat that surrounds and, protects bundles of muscle fibres (called fasicles)., Several such bundles are again covered by, connective tissue to form a muscle block. This, outermost cover is called epimysium., Epimysium is continuous with tendons., The muscle fibres are composed mainly of proteins., About 20% of the chemical constituents of this, tissue is protein, 75% is water and remaining 5%, is composed of inorganic material,, carbohydrates etc., Muscle proteins are characterized by their, elasticity, which confers contractile power on this, tissue., The contractile elements are the minute thread like, myofilaments within the fibre., Myofilaments can again be categorised into thick, and thin filament., Thin myofilaments consist of three types of, proteins actin, tropomyosin and troponin., Myosin is the most abundant muscle protein of, thick myofilament which is globulin in nature., Vladimir Englehardt and Militsa Lyubimova, discovered in 1939, that myosin is an ATPase., , l, l, , l, , l, , l, l, l, l, l, , l, l, , l, , l, , l, l, , Myosin is a very large molecule of molecular weight, 500,000., Actin molecules are filamentous proteins,, consisting of two strings of globular units (G, protein) wound round one another to form a rope, like structure (F actin)., Tropomyosin is a twostranded a helical rod which, is located in the groove between the two helical, strands of actin and blocks the interaction of myosin, head with the actin filament., Troponin is a complex of 3 polypeptide chains, designated as TPC (calcium binding subunit), TPI, (inhibitory subunit) and TPT (tropomyosin binding, subunit)., Myosin and actin are the force generating/, transmitting proteins., Tropomyosin and troponin regulate the interaction, of actin and myosin., Calcium ions triggers the interaction of actin, and myosin., A troponin complex is attached to the tropomyosin, at intervals of about 385 Å., Ca2+, Mg2+ and ATP are required internally for, muscle contraction. ATP and Ca++ are required to, form actomyosin complex and magnesium ion, along with enzyme myosin ATPase and Ca++ is, responsible for the breaking of ATP into ADP,, phosphorous and energy., When Na+ in excess of K+ enters into the muscle,, muscle contraction starts., On the ba sis of structure, loca tion a nd, function, muscular tissue is divided into, striated skeletal muscle, smooth muscle and, cardiac muscle., Skeletal and cardiac muscles are known as, striated muscles because their cells have transverse, stripes and the muscles of the internal organs in the, wall of the bladder, intestine, blood vessels, uterus, and so on are unstriated (also called smooth, muscle)., Striated muscle fibres are present in the body by, attaching to bones by tendons. They are therefore, called as skeletal muscles., Skeletal muscle work according to our will, hence, are voluntary in nature., The voluntary muscle fibres are long and, cylindrical and multinucleated cells upto 40 mm, in length.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ♀ĽřřśĚ–, l, , l, , l, , l, l, l, , l, , l, l, , l, , l, , l, , l, , Their nuclei are located towards the periphery, of the fibre and vacates the central part of the, muscle fibres for myofibrils., Each myofibril of this muscle fibre has alternate, light or isotropic (I band) and a dark or, anisotropic (A band)., A thin Z membrane or Krause membrane is, present in between the light band and a Hdisc or, Hensen’s disc is present in between the dark (or, A) band., The portion in between two Z membrane is a, sarcomere., Sarcomere is the fundamental structural unit of, muscle fibre or myofibril., In the sarcomere –, –, I band has only thin actin filaments (secondary, filament)., –, A band has both actin and tropomyosin and, troponin protein filaments., –, H band has only myosin filaments (primary, filament)., –, Actin filaments are attached on both sides of, Z line., These muscle fibres are richly supplied with blood, vessel (highly vascular), nerves and connective, tissues., They have a network of sarcoplasmic reticulum, and a large number of mitochondria., The neurons which innervate striated muscles come, from the somatic or voluntary branch of the nervous, system., Striated muscle fibre is found in arms, hands, leg,, feet, body wall, tongue and upper part of, pharynx., There are two types of fibres for skeletal muscles, type I (red, slow twitch) and type II (fast twitch, and white)., Type I muscle cells shorten at a relatively slow, speed and generate energy from both fats and, carbohydrates via aerobic metabolism as they have, high concentration of mitochondria, increased, intracellular myoglobin to store and transport O2,, low concentration of glycolytic enzymes used for, anaerobic metabolism., Type II muscle cells are less efficient and are almost, entirely dependent on glycogen as fuel as they have, low concentration of mitochondria, high, concentration of ATP and glycolytic (ATPase), , 291, , Muscle regeneration, Skeletal muscle is a terminally differentiated, tissue. It is no longer capable of undergoing, mitosis. When muscle fibres are damaged (cut or, crushed) they can be repaired by small cells, (satellite cells), little more than nuclei and thin, rim of cytoplasm. They differ from myoblasts., Damage initiates a reaction in which these cells, are activated and fuse with existing fibres to repair, the damaged sarcolemma. There appears to be a, finite number of times that these cells can effect, this kind of repair. After that the muscle can no, longer repair but becomes invaded by scar tissue., This is particularly relevant in muscular dystrophy., , l, l, , l, l, , l, , l, l, l, l, , l, , l, l, , enzymes and a rate of shortening 3 to 5 times that, of a type I muscle cell., The strength of skeletal muscle is directly, proportional to its cross sectional area., Skeletal muscle cells are stimulated by, acetylcholine which is released at neuromuscular, junctions by motor neurons., Smooth muscle is the earliest form of muscle to, evolve., Smooth muscle, a type of non striated muscle, is, also known as visceral muscle as it covers any, visceral organs., Smooth muscle tissue is organized into sheets of, long, spindle shaped cells, each cell containing a, single nucleus., The cells are 50 mm in length and 6 mm in, diameter., Sarcolemma is not always present, however, the, cell has only a thin membrane covering., A smooth muscle fibre is shorter than the striated, muscle fibre., In smooth muscles mitochondria are less in, number and sarcoplasmic reticulum is less, expensive., Functionally smooth muscle fibres are of two, types single unit smooth muscle (found in, gastrointestinal tract and urinary bladder) and, multiunit smooth muscle (found in hair roots and, walls of large vessel)., Smooth muscle fibres are involuntary in nature., The most striking feature of smooth muscle is, the lack of visible cross striations but the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 292, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Distribution and functions of muscular tissues in human body., Functions, , Distribution (location), , 1., , Hair movements, squeezing oil, from oil glands, , Dermis of skin, between hair follicle and, basement membrane of epidermis, , 2., , Digestion, , 3., 4., 5., , 6., 7., 8., 9., , Lips, jaw muscles, tongue, pharynx., Walls of oesophagus, stomach, intestines, and villi, Internal anal sphincter, External anal sphincter, Breathing (ventilation), Diaphragm, intercostal muscles, Blood circulation, Heart, Walls of arteries and veins, Excretion, Walls of renal pelvis, ureters and bladder, Internal sphincter between bladder and urethra, External sphincter near exit from body, Maintenance and change of posture Skeletal muscles, Heat production, Skeletal muscles (exercise, shivering), Vision, Iris, ciliary body, Eye movement, Extrinsic eye muscles, Ejaculation, Wall of genital tract, Parturition, Uterine wall, cervix, Abdominal muscles, diaphragm, Scrotal sac movement, Wall of scrotal sac, , 10. Movement of secretions, , l, , l, , l, , l, l, l, l, , Walls of ducts, , contraction depends on the same proteins as in, striated muscles i.e., actin and myosin and on a, supply of energy from ATP., Smooth muscle cells mediated by the autonomic, nervous system but can also react on stimuli from, neighbouring cells and on hormones (vasodilators, or vasoconstrictor) within the medium that it, carries., Cardiac muscles are found in heart only. Its, function is to pump blood through the circulatory, system by contracting., Cardiac muscles are involuntary, cross striated, (due to Z lines which occurs at regular intervals, along each myofibril) and nonfatigued fibres., It is striated as actin and myosin are arranged in, sarcomere., Cardiac muscles form the myocardium., Each cardiac muscle fibre is formed of several cells, joined together., Intercalated discs are present in between two cells., , l, , l, , l, , l, l, , l, , Muscle Type, Smooth, Striated, Smooth, Smooth, Striated, Striated, Cardiac, Smooth, Smooth, Smooth, Striated, Striated, Striated, Smooth, Striated, Smooth, Smooth, Striated, Smooth, Smooth, , These are the specialized regions of the cell, membrane and functions as boosters for muscle, contraction waves., Cardiac muscles never get fatigued because it, rests and work for equal duration. The resting, period (0.4 sec) is as long as contractive time, (0.1 sec + 0.3 sec)., Fibres of these muscles contain large number of, mitochondria and glycogen granules as they, require large amount of energy., They are richly supplied with blood., Unlike skeletal muscle which contracts in response, to nerve stimulation and like smooth muscle, cardiac, muscle is myogenic, meaning that it stimulates its, own contraction without a requisite electrical, impulse., Cardiac muscle tissue has no regenerative, capacity. During myocardial infarction, cardiac, muscle tissue dies and are replaced by fibroblast, rich scar tissue.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ♀ĽřřśĚ, , A unique aspect of cardiac muscle is the number, of nuclei found inside the cell. Skeletal muscle, cells are multinucleated from the fusion of muscle, cells and smooth muscle cells are strictly, mononucleated, while cardiac muscle cells are, mononucleated, binucleated and multinucleated., In the foetus and post parturition infant most, cardiac muscle cells are mononucleated. Shortly, after birth (within a few months) most cardiac, muscles undergo a change of nucleation from, mononucleated to primarily binucleated, and some, go on to become multinucleated. Generally among, species the cardiac muscle is 90% binucleated cells, and 5% both mono and multinucleated cells, but, exact numbers depend upon the species., , NERVOUS TISSUE, l, , l, l, l, , l, l, l, l, l, , l, l, , Nervous tissue is specialised to react to stimuli, and to conduct impulses to various organs in the, body which bring about a response to the stimulus., Nervous tissue is found in the brain, spinal cord,, and nerves., It is responsible for coordinating and controlling, many body activities., It stimulates muscle contraction, creates an, awareness of the environment, and play a major, role in emotions, memory, and reasoning. To do, all these things, cells in nervous tissue need to be, able to communicate with each other by way of, electrical nerve impulses., Normally the electrical impulse (messages) travel, through a neuron in only one direction., The cells in the nervous tissue that generate and, conduct impulse are called neurons or nerve cells., Neurons forms the structural and functional unit, of nervous tissue/system., Nervous cells originate from embryonic, ectoderm., Neurons occur within the grey matter of the brain,, in spinal cord and in the ganglia of the cranial, and spinal nerves and in the autonomic nervous, system., Neurons are the largest cell in the body., The word neuron was coined by the German, scientist Heinrich Wilhelm Gottfried Von, Waldeyer Hartz in 1981. (He also coined the term, chromosomes)., , l, , l, l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , 293, , Human nervous system has about 100 billion, neurons. Fully formed neurons never divide and, remain in interphase throughout life (unless they, are cancerous)., A nerve is made up of many nerve cell fibres, (neurons) bound together by connective tissue., The parallel bundles of nerve fibres are called, fasiculi., A sheath of dense connective tissue, the, epineurium surrounds the nerve. This sheath, penetrates the nerve to form the perineurium which, surrounds bundles of nerve fibres. Blood vessels, of various sizes can be seen in the epineurium., The endoneurium, which consists of a thin layer, of loose fibrous connective tissue, surrounds the, individual nerve fibres., Endoneurium contains collagen fibres,, fibroblasts, Schwann cells, macrophages and fats, which cushions the nerve fibres (the loss of fat can, lead to pressure on fibres and paralysis)., There are three main types of neurons, which are, classified according their functions : sensory,, motor and interneurons., Sensory (or afferent) neurons conduct impulses, from the sensory organs to the central nervous, system (brain and spinal cord)., Motor (or efferent) neurons conduct impulses, from the central nervous system to the effector, organs (such as muscles and glands). Autonomic, motor or efferent neurons transmits impulses to the, involuntary muscles and glands., Interneurons (also known as connector neurons, or association neurons) are those that connect, sensory neurons to motor neurons as well as, different parts of the central nervous system., On the basis of their structure, neurons can also, be classified into three main types – unipolar,, multipolar and bipolar neurons., Unipolar neurons are sensory neurons, have only, a single process or fibre which divides close to, the cell body into two main branches (axon and, dendrite)., Unipolar neurons are found in embryos and dorsal, root ganglia of adult vertebrates., Multipolar neurons are motor neurons, which have, numerous cell processes (an axon and many, dendrites). Interneurons are also multipolar. Most
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 294, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , neurons in the brain and spinal cord are of this type, (i.e. multipolar neurons)., Bipolar neurons are spindle shaped, with a dendrite, at one end and an axon at the other. An example, can be found in the lightsensitive retina of the eye,, olfactory epithelium and inner ear., Neurons have long processes (neurites), which, extend from the part of the cell body around the, nucleus, the perikaryon or soma., Neurites can be divided into two functionally and, morphologically different groupsdendrites and, axons., Bundles of axons and dendrites are called nerves., They are sensory if they consists of dendrites only,, motor if they consists of axons only and mixed if, they consists of both., The processess of neurons can be demonstrated, by silver impregnation (golgi method) when the, cell appear as browny black silhouettes., Dendrites are part of the receptive surface of the, neurons. It typically carries signal towards the, cell body., Neurons have one to several primary dendrites,, which emerge from the perikaryon. Primary, dendrites may divide into secondary, tertiary etc., dendrites., Some dendrites are studded with small, mushroom, shaped appendages, which are called spines., Each neuron has as a rule one axon, and never, more than one axon which emerges from the, perikaryon or close to the trunks of one of the, primary dendrites., The point of origin of the axon from the perika, ryon is the axon hillock (the most sensitive part)., The axon may, like the dendrites, branch as it travels, through the nervous tissue to its destination(s). The, axon is the “transmitting” process of the neuron., The axon conducts nerve impulses away from, the cell body to another neuron or tissue, therefore, called efferent process., Axon is a longer process and branches distally into, many fine filaments called telodendria., The knobbed ends of telodendria are called end, bulbs, axon terminal or boutons., The cytoplasm of an axon is called axoplasm and, surrounded by a plasma membrane called, axolemma., , l, l, l, , l, l, , l, , l, , l, , l, , l, l, , l, , l, , Nissl bodies are absent in the axon and axon hillock., An axon usually originates from the cell body as, a small conical elevation called the axon hillock., Axon hillock is very distinct from the rest of the cell, body when examined microscopically, it is completely, devoid of the ribosomes, Nissl’s granule, golgi, complex, fat globules and endoplasmic reticulum etc., that characterize the rest of the cell body and the, neighbouring portions of the dentrites. Instead, there, are numerous microtubules and microfilaments, which, form the basis of a transportation system for the axon,, aiding in the movement of substances from the cell, body to the end feet., The axon depend on cell body for proteins., The axons ends in a group of branches, the terminal, arborization. The latter (terminal arborization), when meet dendrites (telodendria) of another neuron, to form a synapse it form synapticknobs (for, motor end plates in muscle fibres and gland cells)., The synaptic knobs contain mitochondria and, secretory vesicles., Synapses are morphologically specialized contacts, between a bouton formed by one neuron, the, presynaptic neuron and the cell surface of another, neuron, the postsynaptic neuron., A typical neuron has about 1,000 to 10,000 synapses, (that is it communicates with 1,000 10,000 other, neurons, muscle cells, glands, etc.)., Synaptic vesicles contains the neurotransmitters., Synaptic vesicles typically accumulate close to the, site of contact between the bouton and the, postsynaptic neuron., The release of the neurotransmitter from the, synaptic vesicles into the synaptic cleft, i.e., the, space between the bouton and the postsynaptic, neuron, mediates the transfer of information, from the pre– to the postsynaptic neuron., Two types of axons are myelinated and, unmyelinated., The myelinated or medullated or white fibre is, surrounded by a phospholipid covering called, myelin sheath., The myelin sheath is produced by flattened cells, called Schwann cells. It consists of 7080% lipids, (fats) and 2030% proteins., Myelin sheath is a layer covering of vertebrate, nerve fibre.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ♀ĽřřśĚ–, l, l, , l, l, l, l, , l, , l, , l, l, , l, l, , l, l, l, l, , l, , The unmyelinated gaps or constrictions in the axons, are called nodes of Ranvier., Myelin serves as an insulating material [as it, coats and insulates the axon (except the nodes of, Ranvier)]. It causes saltatory conduction of, impulses., The conduction of impulses is faster in, myelinated fibres., The cell body of a neuron is called cyton,, perikaryon or soma., Cyton of most neurons in our body occur in brain., The cell body varies in form and size. It may be up, to 13.5 mm in diameter, irregular, rounded star, shaped or pyramidal., Like a typical cell it contains mitochondria, golgi, apparatus, abundant cytoplasm (called neuroplasm), and a relatively large nucleus with a distinct, nucleolus (which is rich in protein) and rough, endoplasmic reticulum., The neuroplasm contains fat globules, pigment, granules neurofibrils, neurotubules and Nissl’s, granules or Nissl’s bodies or trigoid granules., Nissl’s granules are believed to be equivalent to, ribosomes., The neurofibrils (consisting of microfibrils and, microtubules) forms an intricate network both in, cyton and axon and are used in transmission of, impulses., Neurotubules are the microtubules (no centrioles), which maintain the shape of the neuron., The Nissl’s granules (found to be rich in RNA) are, the rough endoplasmic reticulum attached to, ribosomes and polysomes that synthesize proteins, for the cell., The Nissl granules are restricted to cyton,, dendrites and axon hillock., The ageing neuron may contain a pigment called, lipofuscin (derived from lysosomes)., Cyton is concerned with metabolic maintenance, and growth., Nervous tissue also includes cells that do not, transmit impulses, but instead support the, activities of the neurons. These are the glial cells, (neuroglial cells), together termed the neuroglia., Supporting, or glial cells bind neurons together, and insulate the neurons. Some are phagocytic, and protect against bacterial invasion, while others, , l, , l, l, , l, , l, , l, l, , l, , l, , l, l, l, l, , 295, , provide nutrients by binding blood vessels to the, neurons., Neuroglia cells outnumber the neurons and are of, two types macroglia (large glial cells) and, microglia (small glial cell) and play various vital, roles., Macroglia are of two types astrocytes and, oligodendrocytes., Astrocytes (most abundant of all supporting cells, in the CNS) are star shaped glial cells that perform, a variety of functions in the CNS., Astrocytes provide physical support to neurons., They also provide neurons with some of the, chemicals needed for proper functioning and help, control the chemical composition of fluid, surrounding neurons. Finally, astrocytes play a role, in providing nourishment to neurons., Astrocytes also perform a process known as, phagocytosis. Phagocytosis occurs when an, astrocyte contacts a piece of neural debris with its, processe (arm of the astrocyte) and then pushes, itself against the debris eventually engulfing and, digesting it., Astrocytes are of two types fibrous and, protoplasmic., The principle function of oligodendrocytes is to, provide support to axons and to produce the myelin, sheath, which insulates axons. Myelin is 80% lipid, and 20% protein and allows for the efficient, conduction of action potentials down the axon., Microglia are the smallest of the glial cells. Some, act as phagocytes cleaning up CNS debris. Most, serve as representatives of the immune system in, the brain., Microglia are actually a special form of macrophage, (a type of white blood cells involved in fighting, infection and protecting the body), oval in shape, with thorny processes. As such these cells are, actually derived from a blood cell called a, monocyte., Oligodendrocytes resemble astrocytes but processes, are fewer and smaller., Microglia are mesodermal in origin., At 70 years of age, about 20% neurons are, destroyed., Nervous tissue has some properties like excitability, or irritability (ability to perceive a stimulus and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 296, , ŕďőĽę– ĐĽŐńŐĹť, , Components of, Nervous tissue, , Neurons, The information, processing nerve cells, , l, , Human beings contain : 100 billion neurons, Cell body (Soma or Cyton), Th e ce ll body inte grates, information from the dendrites, and other synaptic inputs in, determining the messages to be, transmitted to other cells through, its axon., Neurites, (nerve fibres), , Comprises, , Life span: Neurons, ca nno t gr ow aft e r, damage (except, n e u r o n s f r o m t h e are of two, types, hippocampus), , l, , l, , Supporting cells, (or glial cells), Nonconducting cells that are in, intimate physical contact with, neurons., Provide physical support, insulation,, metabolic exchange with vascular, system., These are ten times more numerous, than neur ons and ar e found, throughout the CNS, Dendrite: Short thick processes, which branch out of the soma,, conduct impulses to the soma., Axon: Long nerve processes,, carry nerve impulses from soma, t o ot h er n euro ns thr o ug h, synapses., , Medullary or myelinated : Contain myelin sheath which, increases the speed of action potential along an axon., Has about 1,000 to 10,000, synapses (the point of, communication between, one neuron to another), , Nonmedullary or nonmyelinated : Lacks myelin sheath and, nodes of Ranvier., , Classification on the basis of, , Properties and characteristics, l Normally the electrical impulses, (messages) travel through a neuron, in only one direction., l The axon may be surrounded by a, ‘coat’ of lipids (fats) and proteins, known as the myelin sheath which, acts as an insulator., l Neurons are specialist cells that, have lost the ability to reproduce, themselves. Once the soma of a, neuron has died the entire neuron, dies, and can never be replaced., l Repair of damaged neurons only, occurs in myelinated neurons., , Structure, Non polar—No functional difference between, dendrite and axon, e.g. Hydra., Unipolar—Single process comes out of the, cell body and divides into two branches., Multipolar—One axon and many dendrites, Bipolar—Two processes; one axon and one, dendrite, Functions, Sensory (receptor)—Brings information to, the CNS, Motor effector—Takes information from, CNS to other parts of body, Interneurons —Help coordinate and, integrate information between sensory and, motor components
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 297, , ○ňĽŇďń– ♀ĽřřśĚ, , l, , l, , l, l, , enter a state of activity), conductivity (ability to, transmit excitation), all or none law, refractory, period, synaptic delay, synaptic fatigue, etc., All or none law states that a nerve conducts a, stimulus when its intensity reaches threshold value., A stimulated nerve fibre conducts the impulse as, per its own characteristic, independent of the, intensity of stimulus., Refractory period is the interval in which a nerve, fails to respond to a second stimulus. It is about, 1 millisecond., Synaptic delay is the time taken for an impulse to, cross a synapse is 0.3 0.5 millisecond., Synaptic fatigue is a temporary suspension of, , l, , impulse transmission in the region of synapse due, to exhaustion., Thicker auditory nerve is found in bat comprising, of 30,000 neurons., Table : Common names of some nerves., Musician’s nerve, Labourer’s nerve, Jacobson’s nerve, , Ulnar, Median nerve, Branch of IXth cranial, nerve, Trigeminal nerve, Trochlear, , Dentist’s nerve, Thinnest & smallest, cranial nerve, Longest cranial nerve Vagus
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 298, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 32, , Integumentary System, l, , l, , l, l, l, l, , l, , l, l, , l, , l, l, , The integument, or skin (cutis) is an anatomically, and physiologically specialized boundary lamina, essential to life., It is a major (and largest) organ of the body,, forming about 8% of its total mass and having an, area between 1.22.2 m2., In total thickness it ranges from about 1.54.0 mm., The study of the structure and functions of the skin, and its derivative is called dermatology., Skin of human is elastic and covered with hair., Skin is a most effective barrier against microbial, invasion and dehydration and against mechanical,, chemical, osmotic, thermal and photic damage., Skin limits and regulates heat loss. Skin is a major, sensory surface with elaborate systems of varied, receptor types, is capable of limited excretion and, absorption and carries out many specialized, biochemical functions, including the formation of, vitamin D3., Skin also has good frictional properties, assisting, locomotion and manipulation by its texture., The outer surface of skin is covered by various, markings, some of them large and conspicuous and, others delicate. These are often referred to, collectively as skin lines., Skin lines include, externally visible grooves of, the epidermis, i.e., flexure lines, positioned near, or opposite synovial joints, tension lines which, form a delicate pattern of geometric shapes over, the surface of thin, hairy skin, and papillary ridges,, forming fields of parallel lines on the thick, hairless, skin of hands and feet., Skin line formed during pregnancy is called, striae gravidarum., Two major classes of skin which cover large areas, of the body, but show important differences of, detailed structure and functional properties are–, , l, , l, l, , l, , l, , l, l, l, , l, l, l, , thin, hairy (hirsute) skin, which constitutes the, great majority of the body’s covering, and thick,, hairless (glabrous) skin forming the surfaces of, the digits., Thick hairless skin forms frictional surfaces for, manipulation and locomotion and requires extra, strength and numerous sweat glands for cooling, during sustained activity., Thin hairy skin is responsible for the general, cutaneous functions over the remainder of the body., Microscopically, skin is formed as an intimate, association between two distinct tissues :, keratinized stratified squamous epithelium, superficially, the epidermis, and a deeper layer of, moderately dense connective tissue, the dermis., Beneath the two layers, a subcutaneous layer of, loose connective tissue or hypodermis is found, which binds the skin to underlying structures., The main function of the subcutaneous layer is, to provide a cushion for delicate organs lying, beneath the skin. It also functions to insulate the, body to maintain body temperature., Texidermy is a process in which epidermis and, dermis both are preserved by chemicals., The epidermis is composed of keratinized, stratified squamous epithelium., The cells present in the epidermis are keratinocytes,, pigment forming melanocytes, phagocytic, Langerhan’s cells, and neurally associated, Merkel’s cells., Small localized accumulations of pigment cells in, the epidermis are naevi or moles., The epidermis is divided into a number of strata, representing different stages of keratinocyte., From deep to superficial, these strata are stratum, basale, stratum spinosum, stratum granulosum,, stratum lucidum and stratum corneum.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▀ňŚĚĹśŇĚňŚďŕť– ☼ťřŚĚŇ–, l, l, , l, , l, , l, l, , l, , l, , l, , Stratum basale and stratum spinosum together, are called stratum malpighii., The cells of stratum basale are active and produce, new cells by mitotic division, hence the name, germinative layer., The rate of cell division in the stratum, germinativum is highest during sleep and lowest, during muscular exercise and stress., The cells of stratum granulosum become, flattened and accumulate many large (0.5 mm), basophil granules., Such cells contain keratohyalin granules., Odland bodies are present in stratum granulosum, and they act as the precursor of skin specific lipid, bilayer., The stratum lucidum is only found in thick,, glabrous skin and represents a rather poorly, understood stage in keratinization., Stratum corneum of epidermis become keratinized, by acquiring keratohyaline protein (in columnar, cells); eleiden protein (in cuboidal cell); keratin, protein (in squamous cell)., In stratum corneum basic protein or profilaggrin, is present which eventually matures into the protein, filaggrin., Filaggrins are an important class of intermediate, filamentassociated proteins that interact with, keratin intermediate filaments of terminally, differentiating mammalian epidermis. They show, wide species variations and their aberrant, expression has been implicated in a number of, keratinizing disorders such as ichthyosis fetalis., , l, l, , l, , l, , l, , The stratum corneum consists of closely packed, layers of flattened, dead keratinocytes (squames)., In thin skin, e.g., of the scalp, this stratum is only, a few cells deep, but in thick skin it may be more, than 50 cells deep., The cells are compact and contain high, concentrations of keratin filaments each about 8, 10 nm thick, often lying parallel and 8 nm apart., Melanosomes are oblong, membranebound,, rounded bodies containing the dark brown pigment, eumelanin., Eumelanin is a highly insoluble, proteinoid, polymer of DOPA quinone, formed by a series of, reactions involving tyrosinase and other oxidative, enzymes., , l, , l, , l, , l, , l, l, l, , l, , l, , l, l, l, , l, l, l, , l, l, , 299, , ‘Voigt lines’ mark differences in pigmentation, between the darker extensor and polar flexor, surfaces of the arms., Pigments of mature skin are usually present only, in the basal layer of epidermis and hair, the chief, being the brown black melanin., A reddishyellow pigment phaeomelanin, is present, in phaeomelanosomes, that occur mainly in reddish, hair., Merkel cells are present only in thick hairless skin,, they are thought to play a role in sensory, transduction., The basement membrane of skin consists of a, basal lamina and it is about 80 nm thick., The dermis consists of irregular, moderately dense,, soft connective tissue., Dermis has its own blood supply due to which, more complex structures are able to exit here, like, sweat glands, to collect water and various wastes, from the blood stream and to excrete them through, pores in the epidermis., The dermis can be divided into two distinct zones–, a narrow superficial papillary layer and a deeper, reticular layer., The papillary layer is immediately deep to the, epidermis and is specialized to provide mechanical, anchorage, metabolic support and trophic, maintenance to the overlaying tissue, as well as, housing rich networks of sensory nerve endings, and blood vessels., Meissner’s corpuscle and nerve endings are, present in papillary layer., The reticular layer is found in close association, with papillary layer., The collagen fibres in the reticular region provide, the skin with strength and extensibility (= ability, to stretch) and elastic fibres provide its elasticity, (= ability to return to the original shape after, stretching)., The gradual stretching of collagen fibres causes, wrinkles in a later life., The dermis is also the site of hair roots where the, growth of hair takes place., In most mammals, there is a layer of subdermal, adipose tissue of fat, forms a continuous layer called, panniculus adiposus., Heat and cold receptors are present in skin., Derivatives of skin may be soft derivative (e.g.,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 300, , l, , l, , l, l, l, l, l, , l, , l, , l, , l, , l, l, l, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , sweat and sebaceous glands) or hard derivatives, (e.g., hairs, scale, beak, horn, claw etc)., The skin glands include sudoriferous glands (secrete, sweat) ; sebaceous glands (produce oily material,, the sebum) ; mammary glands (that secrete milk);, Meibomian glands (which add an oil film into the, eyes); glands of Zeis (that pour oily substances into, the follicles of eyelashes) and ceruminous glands, which secrete wax into the ear canal., Sweat glands are eccrine (similar to apocrine,, cytoplasm is broken before discharge) or merocrine, in nature., Sweat glands are primarily concerned with, regulation of body temperature., Sweat gland maintain homeostasis of water and, salts., Sweat glands are more numerous on palms, soles,, forehead and axillae (arm pit)., Sweat glands are absent in anteaters, sea cows, whales., Sweat contains 95% water, 5% of other constituents, like chlorides, phosphates, ammonia, urea and uric, acid. Sweat is like diluted urine., Sebum produced by sebaceous glands make the, hair soft and supple. It is also antibacterial in, nature., Mammary glands are modified sweat gland in, eutheria or modified sebaceous glands in, prototheria., Meibomian glands are also called tarsal glands, and are modified sebaceous glands on the edges of, eyelids, keep a thin film of oil over the cornea., Zeis glands are sebaceous glands associated with, follicles of eye lashes. Their secretion keeps the, eye lashes smooth and oily., Infection of Zeis gland causes a stye or, hordeolum., Ceruminous glands are modified sweat glands., In amphibia and birds meibomian glands are known, as herdarian glands whose secretion lubricates, the surface of eye ball., Perineal gland, found in dermis of skin around, the genital organs, are modified sebaceous gland., Lacrimal gland has lysozymal protein., Blubber is a very thick layer of adipose connective, tissue found in whale, elephant, seal etc., Tanning is darkening of skin after exposure to UV, light of the sun. It results from darkening of the, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , preexisting melanin followed by rapid synthesis, of fresh melanin., The nails are translucent plates of approximately, rectangular shape lying on the extensor surface of, the distal segment of each digit., The thickness of mature nails varies from about, 0.5 to 0.75 mm., The nail includes three major regions– the, proximal root (radix), the exposed body of the, nail, and the free distal border., Lunula (a white, crescent shaped, half moon shaped, structure) is the most actively growing region of, the nail root., At the attachement site of the nail bed the dermis, is very vascular, accounting for the pink colour, seen through the translucent nail., Microscopically, nails are homologous with the, stratum corneum, consisting of compact, dead,, anucleate keratinfilled squames, derived from the, maturation of cells generated in the germinal matrix, and underside of the proximal nail fold., The nail bed itself is lined by stratified squamous, epithelium in which the surface layer is only, parakeratinized, retaining its nuclei., The rate of nail growth varies with digit, age,, environmental temperature, time of day and other, factors., Generally its speed is related to the length of the, digit, being fastest (about 0.1 mm per day) in the, third digit of the hand (medius) and slowest in, the fifth (minimus)., Finger nails grow up to four times faster than toe, nails., Hairs (pili) are filamentous, keratinized, structures (develop from tubular pits called hair, follicle) present over almost all of the body surface, and are derivatives of the epidermis which assist, in thermoregulation, provide some protection, against injury, have sensory functions and subserve, various subtle roles in social communication., Hairs are absent from a few areas of the body,, including the thick skin of palms, soles and flexor, surfaces of digits and certain other regions like, umbilicus, nipples, glans penis and clitoris, the, labia minora and the inner aspects of the labia, majora and prepuce., In length they range less than a millimetre to more, than a metre, in width from 0.005 to 0.6 mm.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 301, , ▀ňŚĚĹśŇĚňŚďŕť– ☼ťřŚĚŇ, SKIN, Has several layers, , Outer layer, , Epidermis, , has, , no direct, blood, supply, , fed and, supported, by, , consists of, , Layers, , Cell types, Keratinocytes :, Produce a protein the, k er ati n th at he lp s, waterproof the skin and, that protects the skin, and the underlying, tissu es from h eat,, microbes, abrasion and, chemicals., Merkel cells : Sensory, r e c e p t o r s (t o u c h ) ,, associate with a disclike, sensory nerve ending to, form the merkel disc., Melanocytes:, Synthesize is melanin, pigments which protect, the skin against, ultraviolet damage., Langerhans cells :, Macrophages used in, the defense against, micro organisms., , (From the deepest to the, most superficial), , lots of nerve, fibres, sensory, contain, receptors, blood, Inner, equipments and lymphatic, layer, vessels as well, Dermis, as the hair, follicles, and the, sebaceous and, consists, sweat glands., of, two layers, , Malpighian / Basal /, Germinativum, The deepest living epidermal, layer, consists of one row of, cuboidal to columnar shaped, cells. The cells are mostly stem, cells that divide rapidly to, produce new keratinocytes, which push up toward the, surface and become part of the, more superficial layers., , Above basal, , 810 layers thick., The keratinocytes contain, thick bundles of, intermediate filaments, (tonofilaments) made of a, tensionresisting protein., Scattered amongst, ker ati nocy tes are th e, Langerhans’ cells that are, most abundant in this layer., , Papillary Layer, Outer layer closest to the, epidermis, composed of, areolar loose connective, tissue proper., , Fatty layer, (not a part of skin), , Subcutaneous /, hypodermis, Consists of, adipose tissue plus, some areolar, tissue., , Reticular Layer, Deeper layer and the thickest, (4/5 th of the dermis), made, of dense irregular connective, tissue proper containing, thick bundles of interlacing, collagen fibres and some, coarse elastic fibres that run, in several directions., , Outside granulosum, , Stratum, granulosum, (contains, basophilic and, refractile, keratohyaline, granules), The keratinization, process begins and, the cells begin to, die. This layer is, called granulosum,, because the cells, contain granules of, the precursor of, keratin., , Stratum lucidum, Only found in thickened, areas of the epidermis such, as the sole of the feet., The cells appear clear, because of an accumulation, of keratin precursor., The cells begin to, degenerate., After dissolving, keratohyaline granules, transformed into eleidin, which makes cells, semitransparent, shiny and, water proof., , Stratum corneum, , thicker in, Keratin, protein
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 302, , l, , l, , l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Each hair consists of a shaft (scapus) and a root, (radix) lying within a tubular invagination of the, epidermis, the hair follicle (folliculus pili)., At the proximal end of the root the hair is expanded, to form the hair bulb (bulbus), which is continuous, basally with the epithelium of the hair follicle. The, bulb is deeply indented on its deep surface by a, conical vascular dermal papilla., Cells in the bulb are mitotically active., A tiny involuntary smooth muscle called arrector, pili or elevator of the hair operates the hair., The growth rate of hairs varies with their site and, thickness, ranging from about I.5 mm (fine hair), to 2.2 mm (coarse hair) a week when actively, growing., Fast growing hairs are said to be in the anagen, phase, this is followed by the involuting or catagen, , l, l, , l, l, l, l, , l, , phase, when growth ceases, then the resting phase, is telogen phase., No hair follicle develops after birth., Grey hair is the result of a reduction in pigment, formation and reflection of light from an increased, number of air space., Metachrosis is the phenomenon of change in colour, in lower vertebrates., Nail develops from the epidermis., Small scales of dead keratinized epidermal cells, among the scalp hair form dandruff., Albinism is an inherited (usually autosomal, recessive) deficiency or absence of pigment in, the skin, hair and eyes or eyes only due to an, abnormality in the production of melanin., Thinnest skin occurs over the eyelids (0.5 mm, or less).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř, , 303, , Chapter 33, , Morphology & Anatomy, of Animals, EARTHWORM, , l, , (Pheretima posthuma), l, , l, l, l, l, , l, l, l, , l, , l, , The common Indian earthworm, Pheretima, posthuma belongs to class oligochaete of the, phylum annelida., The generic name Pheretima was first used by, Kinbery in 1867., The anatomy of Pheretima has been worked out by, late Professor K.N. Bahl (1926)., Pheretima posthuma is a terrestrial earthworm lives, in damp soil & burrows (fussorial) and is nocturnal., Brown colour of the body is due to a pigment called, porphyrin, present in the circular muscles of body, wall. Porphyrin protects the animal from, ultraviolet rays., Moisture is essential for the survival of, earthworm., Pheretima has no specialized respiratory organs., The moist skin acts as a respiratory organ. The, respiration in earthworm is called cutaneous, respiration., Skin of earthworm is kept moist by mucous,, coelomic fluid & moisture of soil. Mucous serves, not only in respiratory exchange but it also lubricates, the worm body & easy passage through the burrow., The mucous covered skin help in binding soil, particles together & prevents the walls of burrow, from collapsing., In Pheretima, epidermal receptors are present all, over the body. They are of two types –, tangoreceptors (sense of touch) and, chemoreceptors (sense of chemical stimuli)., , l, l, l, , In Pheretima, buccal receptors are found in the, buccal cavity. They are of two types – gustatory, receptors (organs of taste) and olfactory receptors, (organs to detect smell)., If the skin is dry, respiration cannot take place and, the earthworm dies by suffocation., During rainy season it comes out of their burrows, for respiration & to escape from endosmosis., Earthworm lacks a distinct head and sense organs, like eyes, cirri & tentacles., Earthworm do not have special sense organ. Yet, they show behaviour to all kinds of stimuli. This, is mainly due to presence of receptors cells for taste,, touch & apparently vibration all over the body, surface. There is a concentration of sensory cells, at the anterior end of prostomium. Because of these, receptors they feel the vibrations of animals moving, nearby., , l, , l, l, l, , l, , l, , 1st segment (or peristomium) has a ventral mouth, with a dorsal lobe or prostomium & the last, segment has anus., Earthworm has great power of regeneration., Clitellum (or cingulum) is a glandular organ used, for the formation of cocoon., Clitellum completely and permanently surrounds, the segments 14th to 16th in the form of a girdle, like thick band of glandular tissue., Due to presence of clitellum, the body is, distinguished into periclitellar, clitellar and post, clitellar regions., Setae or chaetae (made by chitin) are Sshaped, structures occur in median whorls (perichaetine
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 304, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Number of segment with the structures, located on it in earthworm, No. of segments, , Structures located, , 1st segment, (Peristomium), 6th, 7th, 8th, 9th, 14th to 16th, 14th, 18th, 4th, 5th – 7th, 8th, 15th – last, 17th and 19th, 15th – last, 3rd – last, 4th, 5th, 6th, , Mouth, , 10th, 11th, 13th, 17th, 19th, 16th – 21st, 11th, 12th, 26th – 95th, 7th, 9th, 12th, 13th, 10th, 11th, 5/6, 6/7, 7/8, 8/9, 4th, 5th, 6th, , l, l, , l, , l, , Spermathecae, Clitellum, One female genital opening, A pair of male genital opening, Pharynx, Oesophagus, Gizzard, Intestine, Genital papillae, Septal nephridia, Integumentary nephridia, Pharyngeal nephridia or, branched nephridia, Testes, testis sacs, Ovary, Accessory glands, Prostate gland, Seminal vesicles, Typhlosole, Lateral hearts, Lateral oesophageal hearts, Anterior loops, Spermathecal opening, Blood glands, , arrangement = arrangement of numerous setae in, a ring) in all except first (peristomium), last &, clitellar segments., Setae helps in locomotion by anchoring, structures., In Pheretima, four pairs of spermathecal openings, are present on the inter segmental grooves of 5/, 6, 6/7, 7/8 and 8/9 segments, one pair in each, groove., In Pheretima, single female genital opening is, present on the mid ventral side of the 14th segment, and one pair of male genital openings are seen on, the ventral side of the 18th segment., In Pheretima, close to the male genital pores, two, pairs of genital papillae are present ventrally, one, pair in the 17th segment and the other pair in the, 19th segment. They act as suckers for attachment, during copulation., , l, l, l, l, l, l, l, l, , l, l, l, l, l, l, , l, , l, , l, , l, , Accessory glands of 17th and 19th segments open, to the exterior on genital papillae in Pheretima., The body wall of Pheretima is derived from, ectoderm and somatic mesoderm., Body wall of Pheretima shows circular and, longitudinal muscles., The muscles of body wall of Pheretima help in, locomotion in association with setae., The outer coelomic epithelium of body wall is, made by squamous epithelium., Body cavity is a true coelom (schizocoel),, containing milky white alkaline coelomic fluid., Septa divide coelom into chambers., Coelomic fluid contains corpuscles of following, types– phagocytes (largest, more numerous,, amoeboid corpuscles), mucocytes, circular, nucleated cells and chloragogen cells., Coelomic fluid serves as a hydraulic skeleton, during locomotion., Septal wall is absent in the first four segments, and also between 9th and 10th segments., The speed of progression of Pheretima is 25 cm, per minute., The muscles of alimentary canal of Pheretima, helps in peristalsis., Earthworm has a straight alimentary canal,, representing a tube in tube plan., Pharyngeal glands with some chromophil cells are, present on the roof of the pharynx. They produce, mucin and proteolytic enzymes (protease)., Gizzard (present in the 8th segment) is a thick, walled, highly muscular and lined internally by, cuticle for grinding., In Pheretima, glandular cells of stomach contains, calciferous gland which secrete calcium oxalate and, neutralizes the humic acid of the food., In Pheretima, the dorsal wall of intestine shows, typhlosole. Typhlosole is the largest villus for, increasing absorptive area., In Pheretima the intestine is divisible into 3 parts, based on the presence of typhlosole –, –, Pretyphlosolar region from 15th to 26th, segments., –, Typhlosolar region extends from 27 t h, segment to 23rd or 25th segment in front of, anus., –, Posttyphlosolar region occupies the last 23rd, or 25th segment.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř–, l, , l, l, l, , l, l, l, l, , l, , l, l, l, , l, l, , l, , l, , l, , l, , l, , In Pheretima, the intestine shows a pair of intestinal, caecae in the 26th segment. They extend upto 22nd, or 23rd segment. They secrete amylase enzyme., Earthworms are omnivorous., The food of Pheretima consists of dead and decaying, organic matter mixed in the soil., In Pheretima, undigested food with soil is sent out, through anus in the form of worm castings or, faecal pellets., The digestion is extracellular in earthworm., Blood vascular system of earthworm is a closed, type consisting of blood vessels and capillaries., Blood is red in colour due to presence of, haemoglobin which is dissolved in blood plasma., In Pheretima, there are three main blood vessels, dorsal blood vessel, ventral blood vessel and, subneural blood vessel., Dorsal blood vessel is the largest blood vessel, extending from one end of the body to the other, end. It has thick, muscular walls with valves. It, drives the blood in forward direction., In the intestinal region i.e., behind 14th segment,, dorsal vessel acts as a collecting vessel., The dorsal blood vessel acts as a distributing vessel, in the first 13th segments., The ventral blood vessel extends from one end of, the body to the other end. It is nonmuscular and, nonvalvular vessel., Ventral blood vessel is the chief distributing vessel,, in which blood flows from anterior to posterior end., Subneural blood vessel is present beneath the, ventral nerve cord. It extends from 14th segment to, the posterior end. It is a collecting vessel., Supraoesophageal blood vessel is a short thin, walled collecting vessel lying mid dorsally above, the stomach and confined to segments 9 to 13., On the lateral sides of the alimentary canal from 1st, to 13th segments a pair of lateral oesophageal, blood vessel is seen., A pair of large, thick, muscular and rhythmically, contractile vertical vessels, called hearts, are, present in each of the segments 7, 9, 12 and 13., Lateral hearts that are present in 7th and 9th, segments, connect dorsal blood vessel with ventral, blood vessel., Above the alimentary canal in 4th , 5th and 6th, segments, 3 pairs of globular structures called, blood glands are present. Blood gland produce, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, l, , l, , l, l, l, , l, , 305, , haemoglobin and blood cells., Lymph glands, present on both sides of dorsal, blood vessel from segment 26th and those behind, it, are supposed to produce certain phagocytic cells., In Pheretima, there are three types of nephridia, (ectodermal in origin) according to their location, – pharyngeal nephridia, integumentary nephridia, and septal nephridia., The pharyngeal nephridia are present in 4th, 5th, and 6th segments (one pair in each). Nephrostome, and nephridiopore are absent in pharyngeal, nephridia., Pharyngeal nephridia open in the anterior part of, alimentary canal i.e. buccal cavity and pharynx thus, are also called enteronephric., Pharyngeal nephridia of Pheretima are called, peptonephridia (4 th and 5 th groups open into, pharynx, 6th group opens into buccal cavity)., Integumentary nephridia are microscopic, Vshaped. They are small and have no nephrostome, and are exonephric type., In the clitellar region each segment has 2000 to 2500, micronephridia. They are called forest of nephridia., Septal nephridia are the largest nephridia and the, only nephridia with nephrostome (a ciliated, funnel communicating with the coelom)., The septal nephridia are open to enteronephric, nephridia. They perform both excretion and, osmoregulation., Earthworms are mainly ureotelic (excrete urea)., Chlorogogen cells (or yellow cells) are star shaped,, small sized cells. They perform excretion by, removing excretory products from coelomic fluid., It is bright yellow or orange colour cells derived, from splanchnic peritoneum which explains its, position and distribution on the surface., Chlorogogen cells are analogous to liver of, vertebrates because of the connection with storage, and synthesis of glycogen & fat, deamination &, urea formation., Earthworm has a well developed nervous system,, it has a brain but no head., The nervous system includes a nerve ring around, pharynx in 3rd and 4th segments., Brain hormone produced by suprapharyngeal, ganglia brings regeneration of the posterior, segments., Neurons in earthworm are– motor, sensory and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 306, , l, , l, , l, l, , l, , l, l, l, l, , l, l, l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , adjustor (association neurons)., Photoreceptors of Pheretima contain a Lshaped, lens called phaosome or optic organelle (made up, of a hyaline substance). It cannot form an image., Photoreceptors enable worms to judge the intensity, & duration of light. Photoreceptors restricted to, dorsal surface, are more numerous on, prostomium and peristomium., Pheretima are monoecious or hermaphrodite, organism., In earthworm cross fertilization takes place instead, of self fertilization. This is due to protandrous, condition (where testes mature earlier than ovaries)., In Pheretima, the spermathecae (or receptacula, seminales) show one diverticulum and a big, ampulla. Diverticulum stores sperms and ampulla, gives nourishment to the stored sperms., Copulation takes place for one hour between two, mature earthworms in the night time., Fertilization is external and occurs in cocoon., Cleavage is holoblastic and unequal and, development is direct without any free larval stage., Earthworms are friends of farmers because they, enrich the soil by nephridial excretion, that increases, the fertility of soil., Earthworms found in South India are Megascolex,, Lampito, Octochaetus, Drawida, Eutyphaeus etc., Drawida grandis is the largest earthworm in, India., Largest earthworm in world is Megascoloides, australis., Megascolex is abundantly found in Andhra Pradesh., Pheretima and Eutyphaeus are found in North India., Pheretima posthuma is also found in Kerala state., Lumbricus terrestris is an European earthworm, not, found in India., Allolobophora is found in hilly regions of, North India., , COCKROACH, , l, , l, l, l, l, l, , l, , l, l, l, , l, , l, l, , l, , (Periplaneta americana), l, l, , l, , Cockroaches belong to the class insecta of phylum, arthropoda., Class insecta is the largest in the animal kingdom,, as there are more species of insects (about 80,000), than all other species of animals combined., Four species of cockroaches found in India are–, Blattella germanica (the German or croton, , l, l, l, , cockroach); Blatta orientalis (the Oriental or Indian, cockroach); Periplanata americana (the American, cockroach or ship cockroach); and Periplaneta, australasiae (the Australian cockroach)., Cockroaches are nocturnal (active in night),, cursorial (fast runners) and omnivorous and, scavangerous in diet., Blatta orientalis is black in colour and it is, commonly known as black beetle., Periplaneta americana is the largest and most, common species., The wings are well developed in both sexes of, Periplaneta americana and extend beyond the body., The wings are reduced in male and vestigial in, female Blatta orientalis., Body is covered with nonliving, brown coloured,, hard jointed and chitinous exoskeleton of sclerites, which are formed by thin, flexible arthrodial or, articular membranes to allow movements., The dorsal sclerite of the exoskeleton of cockroach, is called tergum or tergite, ventral sclerite is, sternum or sternite and two lateral sclerites are, called pleura or pleurites., Body of cockroach is distinctly divided into head,, thorax and abdomen., The part of head between and behind the eyes is, epicranium (vertex)., The front of head capsule is made up of three, unpaired flattened sclerites called frons, clypeus, and labrum., Head bears a pair of long antennae, a pair of ocelli, or fenestrae (simple eyes) and a pair of compound, eyes., The thorax of cockroach consists of three segments –, prothorax, mesothorax and metathorax., Thorax bears three pairs of jointed appendages, (walking legs) and two pairs of wings on, mesothorax and metathorax., Abdomen is the largest and broadest part, consisting of ten segments (11 segments in, embryo) without appendages., The 11th somite of embryo is represented in adult, by podical plates., Abdomen is long & narrow in male but is short, and broad in female., 8 pairs of tracheal openings or spiracles are, present on lateral pleura of first 8 abdominal, segments.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř–, l, , l, , l, l, l, , l, , l, l, , l, , l, l, l, , l, , l, l, , l, , l, , l, , Main appendages of cockroach are antennae and, mouthparts (on head); legs and wings (on thorax), and external genitala (on abdomen)., The antenna is made of many segments called, podomeres. The first segment is scape (largest),, second pedicel and rest many jointed flagellum., Antenna is a thigmoreceptor sensitive to touch and, smell., Mouthparts of cockroaches are mandibulate type, or cutting and chewing type., Mouthparts consists of labrum (upper lip), labium, (lower lip), maxillae (segmented and resemble to, a leg), mandibles and hypopharynx (tongue)., The main structures and well developed part of, mastication (chewing) are mandibles which are, short with teeth., The mandibles work as jaws and are used for, crushing and cutting the food materials., Each leg of cockroach (used for walking, running, and climbing) is made up of 5 segments (or), podomeres. They are coxa, trochanter, femur,, tibia and tarsus., Tarsus is subdivided into five tarsomeres. The last, tarsomere is called pretarsus forming the claws and, bearing an adhesive arolium or pulvillus., Similar but smaller adhesive pads called plantula, are located at each joint of the tarsus., The most swollen segment in the leg of cockroach, is coxa., Tibia is the largest podomere in the leg of, cockroach. The bristles on tibia are called tibial, spurs., Mesothoracic wings or forewings are thick, leathery and opaque wings. They are not used in, flight but protective in function., Metathoracic or hindwings are broad, thin and, membraneous wings which are used in flight., Anal cerci and anal styles are the external genitalia, which are involved in sexual dimorphism, mating, and deposition of eggs., Anal cerci, a pair of many jointed structures are, present on the tergite of 10th segment in both, sexes., Anal styles, a pair of small, spinelike unjointed, structures are present on sternite of the segment, in males only., Body wall of cockroach is made up of two layers , outer cuticle and inner hypodermis., , l, , l, , l, , l, l, , l, l, , l, l, , l, , l, l, , l, , l, , l, l, l, , 307, , Cuticle is invaginated forming endoskeletal, elements like tentorium in head and apodemes in, thorax. They provide sites for attachment of, muscles., Cuticle is principally made of chitin, a horny, proteinous substance, chemically an amino, polysaccharide, insoluble in water and resistant to, most solvents., The cuticle has three distinct layers: outer primary, cuticle or epicuticle, middle thick exocuticle and, inner thick endocuticle. All three are secreted by, hypodermis., Exo and endocuticle together constitute the so, called ‘procuticle’., Exo and endocuticle contain chitin, a structural, polysaccharide, basic unit being Nacetyl, glucosamine., Melanin pigment is found only in exocuticle., Hypodermis is a single layered epithelium. Some, of its cells are modified into large oval trichogen, cells concerned with secretion of movable bristles, on the body of cockroach., Besides secreting cuticle, hypodermis resorbs, endocuticle before each moult or ecdysis., The alimentary canal is long and divisible into, three main parts namely foregut, midgut and, hindgut., Foregut (stomodaeum) is differentiated into five, parts: buccal chamber, pharynx, oesophagus,, crop and gizzard., Crop or ingluvius occupies the entire thoracic and, some abdominal part and stores the food., Gizzard is adapted for grinding the food into a pulp., The main part of gizzard is called armarium, [anterior part with teeth (which masticate the food), and pulvillii (whose bristles form a strainer which, allow only fine food particles to pass through)]., Stomodeal valve is posterior narrow and tubular, part of gizzard which projects into the midgut to, prevent backflow of food., From the junction of midgut and gizzards arises, seven to eight finger like structures called hepatic, caecae., Midgut (mesenteron or ventriculus) is short,, tubular lined with glandular endoderm., Midgut forms the true stomach serving mainly for, digestion and absorption., Internally mesenteron is not lined by cuticle but it, is covered by a very thin and transparent
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 308, , l, , l, l, l, , l, l, l, l, , l, , l, l, l, l, , l, , l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , peritrophic membrane formed of chitin and, proteins., Peritrophic membrane is secreted by stomodeal, valve of gizzard and serves to protect the wall, of midgut from abrasion due to friction of food, particles., Hindgut (proctodaeum) comprises ileum, colon, and rectum., Most of the nutrients of food are digested in the, crop., Digestive glands includes one pair of salivary gland,, each is formed of two parts sac like resorvoir or, (receptacle) and a bipartite glandular part., The digestive enzymes of saliva are mainly zymase, and amylase., Digestion is intercellular in cockroach., Absorption of digested food takes place in, mesenteron., Circulatory system of cockroach is open or, lacunar type. The blood flows through, haemocoelic system., Haemocoel is divided into a dorsal pericardial sinus, (containing heart), a middle perivisceral sinus, (containing the gut) and a ventral perineural sinus, (containing the nerve cord) by two perforated, diaphragms., Heart is longitudinally beaded with 13 chambers, perforated by ostia having valves., The blood circulation is maintained by 13 pairs, of wingshaped involuntary alary muscles., Heart of cockroach is neurogenic (myogenic in, frog, rabbit and man)., In addition to the main heart there are present very, small accessory heart or pulsatile vesicles one at, the base of each antenna located in the head, to, pump the blood from the head sinuses to the, antenna., The blood of cockroach is colourless due to the, lack of respiratory pigment. It consists of, colourless plasma and corpuscles called, haemocytes., Pacemakers are absent in the cockroach heart., In cockroach, oxygen is carried to individual cell, without participation of blood., All body tissues receives oxygen directly., The rate of heart beat in Periplaneta is 49/min., Blood circulartion in cockroach is completed in 5, 6 minutes., , The pathways follow as, Heart, Aorta, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Head sinuses, , Perivisceral, Perineural, Pericardial, sinus, sinus, sinus, Respiratory system of cockroach consists of, tracheal system (containing tracheae, tracheoles, and spiracles)., The tracheal system open outside by ten pairs of, spiracles or stigmata (two pairs thoracic and eight, pairs of abdominal). The spiracles are with valves., The trachea is lined with spiral thickening of cuticle, called intima or taenidia which prevents the, tracheal tubes from collapsing (trachea of rabbit is, also noncollapsible)., Ventilation of tracheal system is by alternate, contraction and relaxation of abdominal muscles, (tergosternal muscles)., Respiratory movements depend on the activity of, insects and temperature, greater the muscular, activity the more vigorous is the pumping in and, out of air., Respiratory movement are coordinated and, regulated by nerve centres in thoracic ganglia, which are stimulated by low O2 and higher CO2, concentrations in tissue fluids., Tracheal systems of respiration is also found in, centipedes, millipedes, ticks and Peripatus., Excretory organs of cockroach are malpighian, tubules [long, very fine unbranched yellow, coloured blind tubules attached at the junction of, midgut and hindgut (ileum)], fatbody cells; uricose, glands and cuticle., Malpighian tubules absorb excretory substances, from haemolymph and fat bodies and pass into, the proctodaeum., Fat body of cockroach contains mainly four types, of cells, viz., trophocytes, mycetocytes, oenocytes, and urate cells., The trophocytes are most numerous containing, reserve food in the form of fats, glycogen and, proteins., Mycetocytes contain symbiotic bacteria which help, in synthesis of some amino acids, vitamins and of, glycogen from glucose., Oenoctyes are supposed to help intermediary, metabolism at times of ecdysis. It secretes wax
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř, , l, , l, l, , l, l, , l, , l, , l, , l, l, , l, l, , l, l, , l, , which covers the cuticle of cockroach., Urate cells absorb nitrogenous waste products from, haemolymph and synthesize uric acid from these, for storage (storage excretion)., The fat body of cockroach is functionally, analogous to liver of vertebrates., Uricose gland are long, blind tubules present at the, periphery of mushroom gland in the male, cockroach., These tubules store uric acid and discharge it over, the spermatophore during copulation., Uricose gland serves as storage excretory organs, between matings and as active excretory organs, during copulation., Excretory products of cockroach are uric acid, (hence uricotelic) and urates of sodium and, potassium, so they are uricotelic., The nitrogeneous waste which are deposited, beneath the cuticle are eliminated by the body, during moulting (ecdysis)., Nephrocytes are large colourless ovoid binucleate, cells attached to diaphragm in the body cavity. These, are arranged on the lateral sides of heart hence also, called pericardial cells, which probably, regulates the pulsation of the heart and also help, in excretion., Cockroach has a well developed nervous system, with central, peripheral and sympathetic system., Central nervous system consists of cerebral or sup, raoesophageal ganglion (brain), suboesophageal, ganglion, paired circumoesophageal connectives, and double ventral nerve cord (with three thoracic, and six abdominal compound segmental ganglia.), The total number of ganglia in ventral nerve cord, of cockroach is nine., Sense organs in cockroach are – photoreceptors, (compound and simple eye), thigmoreceptors, (antennae), chemoreceptors (on maxillary and, labial palps, labuim and hypopharynx) and auditory, receptors on anal cerci., Each compound eye of cockroach is composed of, about 2000 visual units called ommatidia., Each ommatidium is composed of a cuticular lens,, two corneagen cells, a crystalline cone surrounded, by four cone cells, a rhabdome surrounded by seven, reticular cells and a basement membrane., There are two types of vision in insects – mosaic, vision (or apposition image) during day time and, , l, , l, l, , l, l, , l, l, , l, , l, , l, l, l, l, l, l, l, , l, l, l, , 309, , superposition (or dull image) in dim light., But in cockroach, pigment sheath of ommatidia, is noncontractile so capable of only mosaic vision, even during night., In cockroach, sexes are separate, so dioecious., Male organs consists of testes, vasa deferentia,, ejaculatory duct, mushroom or utricular gland,, phallic or conglobate gland and male, gonaphophysis., Testes of cockroach are located in the abdominal, segments 4, 5 and 6., Mushroom gland consists of two types of tubules, the long slender tubules, the utriculi majores or, peripheral tubules; and short tubules, the utriculi, breviores, making up of the major part of the, gland., All sperms of a seminal vesicle are glued together, into a large bundle called spermatophore., Spermatophore has threelayered wall: inner layer, secreted by utriculi majores; middle layer secreted, by ejaculatory duct and outer layer secreted by, phallic gland., There are three asymmetrical chitinous structures, called male gonapophyses or phallomeres. These, are right phallomere, left phallomere (largest) and, ventral phallomere (smallest)., Female organs consist of ovaries, oviducts,, vagina, genital chamber, spermathecae,, collaterial glands and female gonapophysis, (ovipositor processes)., Copulatory organ of cockroach is pseudopenis., Copulation in cockroach occur at night., Each ovary (located in the abdominal segments 2, to 6) of cockroach consists of eight ovarioles., The egg of cockroach is centrolecithal type, yolk, being in the centre., Nymph of cockroach emerge out from ootheca., Nymph of cockroach undergoes 13 moults to reach, the adult form., Ootheca or egg case (formed of a protein secreted, by collaterial gland) of cockroach contains, sixteen fertilized eggs., Metamorphosis in cockroach is incomplete or, paurometabolous type., Instar is a stage in the development of insect (larval, instar, nymphal instar)., Period between two moults in insects is termed as, stadium.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 310, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Periplaneta americana has 11 nymphal instars in, female and 12 nymphal instars in male. Blatta, orientalis moults 6 times., Gonapophyses acts as external genitalia & help, in copulation., Metamorphosis is regulated by two hormones,, ecdysone (secreted by prothoracic glands) and, juvenile hormone or neotinin (secreted by corpora, allata)., , FROG (Rana tigrina), l, l, , l, l, , l, l, , l, l, l, l, , l, , l, , l, , l, , Frog, belongs to amphibia class of vertebrate, is a, cold blooded or poikilothermic anamniote., Frog is selected for type study due to being non, poisonous, easy to procure, less expensive, kept, alive in captivity for a long time very easily and its, internal anatomy can be seen by simply opening its, body cavity., Frog is an amphibious animal i.e., it lives in fresh, water and on terrestrial environment., Because of possessing amphibious mode of life frog, has streamlined body, the characteristic of the, aquatic animals assisting in swimming in water., The body of the frog is divided into head and trunk,, the true neck and tail of tadpole being absent., Because frogs have eyes and nostrils on the top of, their head, they can see and breathe while the rest, of the body is under water., Frogs have smooth skin and long legs to help them leap., Skin of frog consists of two types of glands:, mucous and poison glands., Both glands are the derivative of epidermis but, lying in the dermis., The mucous glands secretes a colourless watery, fluid (mucous) that keeps the skin moist, glistening, and sticky, whereas the poison gland secrete a mild, poison for protecting the animal from the enemies., Skin of frog forms a chief respiratory organ as its, moist surface brings about an exchange of, respiratory gases in between the body of the animal, and the environment., Being devoid of sweat glands, skin of frog acts as, an excretory organ as the shedding of stratum, corneum helps in removing the excretory wastes., Skin of frog larva produces certain enzymes (called, hatching enzymes) which dissolves the egg, membrane and help in hatching., Exoskeleton is absent is frog., , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, l, , l, l, , l, , l, , Frog’s endoskeleton is made by bones and cartilage., But in tadpole larva the entire skeleton is, cartilaginous., The skull of frog is dicondylic and consists of the, following regions cranium, olfactory capsule,, auditory capsules, orbits, upper jaw, lower jaw and, hyoid apparatus., The skull of frog is platybasic i.e., an interorbital, septum is absent and cranium extends beyonds, orbits., Cranium is made by 6 bones and divisible into 3, regions occipital region, frontoparietal region, and ethmoid region., Occipital region is formed by two irregular, exoccipital bones (replacing bones) which are, present on either side of the foramen magnum., The roof of the cranium is constituted by two, frontoparietals fusing in the middle line forming, compound bones (In tadpole stage these two bones, are distinct)., The floor of the cranium is covered by a median, dagger shaped or inverted Tshaped bone called, parasphenoid., Sphenethmoid, a ring shaped girdle bone, surrounds the anterior part of the cranium and, is divisible into an anterior ethmoidal portion, and a posterior sphenoidal portion., Auditory capsule consists of prootic bone (saddle, shaped cartilage bone) in the anterior face,, columnella auris (derived from hyomandibular), and stapedial plate (cartilage) in the middle ear., Auditory capsules communicates by fenestra, ovalis., Fenestra ovalis is the opening of prootic bone in, which the columnella auris fits in., Olfactory capsule consists of ethmoidal portion of, sphenethmoid, paired nasal, vomers and, septomaxillaries., Nasals are large triangular bones covering the roof, of olfactory capsules., Vomers form the floor of the olfactory capsules,, bearing about seven vomerine teeth in the posterior, margin of each bone., Septomaxillaries are a pair of small irregular bones, bounding external nares. Each consists of a basal, plate, small limb and a large limb., Upper jaw consists of premaxilla (anterior most, bone of upper jaw with four to five teeth), maxilla
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř, , l, , l, , l, , l, l, , l, , l, l, , l, , l, l, l, , l, l, l, l, , (side bone of upper jaw with four to five teeth) and, quadratojugals (coma shaped, small slender bone, of posterior outer margin of upper jaw)., Quadrate cartilage is found at angle of jaw. It is, attached to lower jaw through autostylic, suspensorium., Three pairs of suspensoria bones connecting upper, jaw with cranium are : palatines, pterygoids and, squamosals., Lower jaw consists of mentomeckelian (found at, the tip of lower jaw), dentary (outer surface of, anterior half of jaw), angulosplenial (3 pair of, bones, at the inner surface and lower edge of the, jaw) and Meckel’s cartilage (found at the articular, surface)., Teeth are entirely absent in the lower jaw of frog., Hyoid apparatus lies in the floor of, buccopharyngeal cavity and provides attachment, and support to the tongue., Hyoid apparatus consists of body (a cartilaginous, plate), alar processes (also called anterior process, ‘wing like’), posterior processes (present in, posterior lateral margin), anterior cornua (two long, processes articulating with auditory capsule) and, posterior cornua (two short processes, replacing, bones)., Frog has total ten vertebrae including urostyle., First vertebra is called atlas with reduced centrum, and without prezygapophyses and transverse, processes., 2nd to 7th vertebra have same structure, called, typical vertebrae, characterized by procoelous, condition, centrum concave in front and convex, behind., 8th vertebra is amphicoelous as the centrum is, biconcave., 9th vertebra is acoelous as the centrum is convex, on both the sides., 9th vertebra is also called sacral, its transverse, processes are backwardly directed and articulated, with ilium of pelvic girdle (sacroiliac joint)., Urostyle is the 10th vertebra, as long as remaining, vertebral column., Urostyle has dorsal keel or crest or ridge., Spinal cord in frog extends up to the anterior part, of urostyle., Ribs are absent in frog, so sternum (also called, breast bone) articulates directly with the pectoral, girdle., , l, , l, l, , l, l, , l, l, , l, l, l, l, l, l, l, , l, , l, l, l, , l, , 311, , Sternum of frog has four parts : episternum, (anterior flattened circular cartilage), omosternum, (inverted ‘Y’ shaped cartilage bone articulated with, clavicles), mesosternum (rodlike cartilage bone, articulated with epicoracoids), xiphisternum, (terminal circular cartilage)., Vertebral column terminates by urostyle in frog,, coccyx in man and pygostyle in bird., Each half of pectoral girdle consists of, suprascapula (a calcified cartilage), scapula,, coracoid, precoracoid, epicoracoid and, paraglenoid cartilage., Clavicle is a slender rod, separated from the coracoid, by a wide gap called coracoid foramen., In between the coracoid and clavicle a big space is, present. It is called coracoid fenestra or coracoid, fontanella., In frog the pelvic girdle is Vshaped and composed, of two similar halves called osinnominatum., Each osinnominatum is composed of 3 bones, ilium (greatly elongated and forms the major part),, pubis (smallest, triangular calcified cartilage) and, ischium., The bones of forelimbs includes humerus, radio, ulna and the bones of hand., There are four digits in forelimbs and five digits, in hindlimb., The bones of hindlimbs includes femur, tibiofibula,, astragalus, calcaneum and bones of foot., Tibio fibula is the longest bone in frog., Tibio fibula forms knee joint with femur., Digital formula of forelimb and hindlimb are 0, 2,, 2, 3, 3 and 2, 2, 3, 4, 3 respectively., The digestive system of frog shows two parts– food, catching organ, the alimentary canal and, the digestive glands., Alimentary canal consists of mouth,, buccopharyngeal cavity, oesophagus, stomach,, duodenum, ileum, rectum, and anus which opens, out by cloaca., Digestive glands include liver, pancreas and the, glands of gut wall., Salivary glands are not present in frog., The buccopharyngeal cavity is bounded by upper, and lower jaws. At the floor of the cavity, there is, a sticky tongue. It is useful to catch the prey., The teeth are pleurodont, homodont and, polyphydont type. There are also a pair of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 312, , l, l, l, , l, , l, , l, l, , l, l, l, l, l, l, l, , l, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , vomerine teeth. Teeth are useful only to avoid the, escape of the prey., Oesophagous is very short due to absence of neck., The food taken by frog includes proteins, fats,, carbohydrates, vitamins and mineral salts., Frog is carnivorous in its feeding habit and feeds, on small insects, spiders and earthworm which are, caught by throwing out the extensible sticky mucous, coated tongue., Digestion starts in the stomach by the action of, gastric juice. Food is completely digested in the, intestine by the action of pancreatic juice and succus, entericus., The end products of digestion are aminoacids from, proteins, glucose from carbohydrates, fatty acids and, glycerol from fats., Digested food is absorbed by villi of intestine and, undigested food is sent out through cloaca., Frog respire by means of cutaneous respiration, (skin),, buccopharyngeal, respiration, (buccopharyngeal cavity), and pulmonary, respiration (lungs)., In frog, diaphragm is absent and is not related, with respiration., Contraction of sternohyal muscle during breathing, lowers floor of oral cavity., Contraction of petrohyal muscle during breathing, raises the floor of buccal cavity., Epithelial lining of the alveoli of frog’s lung facing, lung cavity is columnar and ciliated., During pulmonary respiration of frog, mouth, remain closed., In frog, glottis is controlled by muscles of arytenoid, cartilages., The lungs of frogs are not only the organs of, respiration but also an hydrostatic organ as they, enable frog to float in water when they are inflated., In frog cutaneous respiration takes place always,, therefore frog dies if the skin dries up as the, cutaneous respiration is impaired., During severe cold winter frog will go for winter, sleep or hibernation., During winter sleep lung breathing is stopped, while, skin breathing continues which suffice the need of, oxygen., During severe summer frog will go for summer, sleep or aestivation., In this state it performs minimal metabolic activities,, , l, l, l, l, , l, , l, l, , l, , l, l, l, l, l, l, , l, l, l, , l, , minimal cutaneous respiration and excrete uric acid., The spring and rainy seasons are the periods of, great activity for the frogs., The circulatory system of frog shows blood, vascular system and lymphatic system., The life span of RBC in frog is 100 days., The heart of frog is three chambered with two, auricles and one ventricle. It is enclosed in double, walled pericardium. Two additional chambers are, also present, these are sinus venosus and truncus, arteriorus., The circulation can be described as incomplete, double circulation. The blood is pumped to various, parts of the body by arteries which constitute the, arterial system. Various veins of the venous system, collect the blood and bring it to the heart., The portal system is well developed with both, hepatic and renal portal systems., The hepatic portal system has much significance, by taking the end products of digestion first to the, liver., The renal portal system is significant by taking, the impure blood to the kidney where it is filtered, even before it reaches the heart., The lymphatic system is closely associated with, blood vascular system., The lymphatic system consists of lymph capillaries,, lymph vessels, lymph hearts and lymph sinuses., A colourless fluid called lymph flows through the, lymphatic system., Lymph acts as middle man between vascular system, and tissue fluids., Spleen is the largest lymphatic gland., At the base of the internal carotid artery of frog, carotid labyrinth is present. It work as chemo and, baroreceptor., The sequence of heart contraction in frog are sinuous, venousus, auricles and ventricles., The frog has a highly developed nervous system., It consists of brain, a spinal cord and nerves., Frog has ten pairs of cranial nerves arises from, brain (olfactory, optic, oculomotor, trochlear,, trigeminal, abducens, facial, auditory,, glossopharyngeal, vagus) and 10 pairs of spinal, nerve., Frog shows monocular visions as the two eyes are, situated far away from each other over the head and, their images also do not coincide.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř–, l, l, , l, , l, , l, l, l, l, , l, l, , l, l, l, l, l, l, l, l, l, l, l, l, , Frog eye has no power of accommodation., Harderian gland present at the inner angle of the, eye, produces oily secretion, which lubricate the eye, ball and nictitating membrane., The external ear is absent in frog. Both ear drums, or tympanic membrane are exposed. These is only, bone in the frog’s middle ear., In frog the excretory system and reproductive, system are intimately associated. So these two, systems are together referred as urinogenital, system., The excretory system consists of a pair of kidneys,, a pair of ureters, the urinary bladder and cloaca., Each kidney consists of a large number of excretory, units called uriniferous tubules or nephrons., The nephron is divisible into two parts namely the, malpighian capsule and nephric tubule., The malpighian capsule is the filtration unit of, excretory system and the nephric tubule is useful, for secretion and selective reabsorption., The main excretory product in frog is urea., The urea along with some unnecessary salts and, water is collected into the urinary bladder in the, form of urine. It will be stored there for some time, and is sent out through cloaca. So frog is described, as ureotelic animal., Excretory product of tadpole larva is ammonia., Kidneys are pronephros in tadpoles and, mesonephric in adult frog., Frog shows sexual dimorphism. Male frog shows, vocal sacs and nuptial pads., Vocal sacs are present at the junction of two jaws, on the ventral side of the head., Vocal sacs are resonators of the sounds and, produce croaking sound., Amplexusory pads or nuptial pads are present on, the index finger of the forelimb., These pads help male animal to clasp the female, firmly during copulation., The forelimbs of frogs are short and hindlimbs of, frogs are long. Long hind limbs help in leaping., Neck is absent in frog as an aquatic adaptation., The posterior end of trunk of frog show cloacal, aperture., In frog testis is attached to the kidney by, mesorchium (peritoneal layer)., In adult male toad bidder’s organ is present. If, testes are removed bidder’s organ will become, ovary., , l, l, l, l, , l, l, l, l, , l, l, l, , 313, , The mass of sperms liberated by male frog is called, milt., The mass of eggs liberated by female frog is called, spawn., In frog fertilization is external., Zygote undergoes cleavage and develops into, morula and blastula. The cleavage is holoblastic, and unequal., The blastula changes into gastrula by epiboly,, modified invagination and involution., The gastrula has three germ layers which further, differentiate and give rise to various organs., The life history of frog includes three stages egg,, larva and adult., The tadpole undergoes metamorphosis to become, the adult. The metamorphosis is complete. Finally, the aquatic gill breathing, herbivorous, fish like, tadpole transforms into an amphibious, lung, breathing, carnivorous adult frog., Thyroxine controls the metamorphosis in frog., The tail of tadpole is the locomotory organ., During metamorphosis the tail is absorbed by auto, phagocytosis., , RABBIT (Oryctolagus cuniculus), l, l, , l, l, , l, l, , l, l, l, , Oryctolagus cuniculus or the rabbit is a fossorial,, nocturnal, herbivorous, and polygamous animal., Rabbit is crepuscular(that is coming out of burrows, for feeding in twilight chiefly at dawn or dusk),, timid, can be domesticated., Its body is pointed anteriorly and broad, posteriorly which is covered with fur and hairs., The rabbit are gregarious in habit i.e. they live in, groups and even several families consisting of, hundred of rabbits may live in one burrow., The body is divided into head, neck, trunk (which, is divided into thorax and abdomen) and tail., Head is large, pear shaped, distinct and anterior, pointed blunt snout has a terminal, transverse slit, like mouth, which is divided into left and right, equal halves due to a vertical cleft, which continues, upto the nostrils. Such divided lips are known as, hare lip., Due to hare lip front incisors are exposed., From the sides of upper lip thick tactile hairs or, vibrissae or whiskers project outward., Vibrissae are stiff, long and sensory in function, because they have nerve ending at their base.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 314, , l, , l, , l, , l, l, l, l, , l, , l, l, , l, l, , l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Nictitating membrane is present in the inner corner, of the eye, which is movable and used for cleaning, cornea., Just above the mouth, large, oblique slit like,, olfactory nostrils are present which is respiratory, in nature., Ear opening is surrounded by movable pinna., Tympanic membrane is sunken at the base of, external auditory meatus., Vocal sacs are absent., Neck is short, flexible and well demarcated from, head and trunk., Trunk is differentiated into anterior thorax and, posterior abdomen which is covered with hairs., Paired forelimb and hind limbs are present. Forelimb, bears 5 clawed digit adapted for digging the, burrow. Hind limb bears 4 clawed digit, which, is adapted for walking and leaping., On the ventral side between thorax and abdomen, 45 pairs of teeths or nipples are present which are, functional in female only., Separate anus and urinogenital opening present at, the hind end., Short, bushy, curved upward tail is present. Tail is, used for giving warning, signals, when danger, approaches and as balancer during leaping., A female reaches maturity at the age of 6 months, only and average life span to about 8 years., At the time of birth the young are blind, deaf, naked, (hairless) and helpless. They are fed on milk by, mother who shows parental care., They show coprophagy or rejection, by eating their, soft night doppings without mastication, so the same, food passes twice through gut to provide maximum, nourishment., Skin of rabbit is made of epidermis and dermis., Epidermis is highly stratified. Stratum corneum is, composed of hard, scalelike, dead, fully,, keratinized flattened cells., The complex epidermis is primarily made of two, zones–the deep malpighian layer and the, superficial cornified layer., Malpighian layer is further divided into stratum, germinativum, stratum spinosum (also called, prickle cell layer), stratum granulosum and, stratum lucidum., The outermost cells on the skin surface are thin dead, and fully keratinized., , l, l, , l, l, l, l, , l, , l, l, l, l, , l, , l, , l, l, , l, l, , l, l, , Stratum granulosum contains basophilic and, refractile keratohyaline granules., In stratum lucidum, keratohyaline granules are, dissolved and transformed into eleidin which makes, cells semitransparent, shiny and waterproof., In stratum corneum, eleidin is replaced by keratin,, a scleroprotein which is insoluble in water., When keratin is synthesized in a cell, the cell is said, to be keratinized or cornified and it dies., The cells of stratum corneum are nonliving,, flattened, keratinized without nuclei., Presence of dead dry cornified cells of stratum, corneum helps to prevent evaporation of water, from its surface., Dermis is thickest, consists of connective tissue, fibres, unstriped muscles, blood capillaries, nerves,, fat cells, tactile receptors and pigment cells., Deeper part of the dermis is composed by subdermal, adipose tissue or panniculus adiposes., It is concerned with storage of fat., Pigment granules are present in the hairs. Pigment, cells found in the basal layer of epidermis., Skin is highly glandular due to presence of sweat, glands, sebaceous glands, mammary glands and, scent glands, but mucous gland is absent., Skin or integument serves a variety of important, functions like it gives shape, protection, defence,, homoiothermy (maintenance of a fairly constant, body temperature), synthesis of vitamin D,, excretion, secretion, sexual selection etc., The skull of rabbit consists of two main regions–, posterior cranial region and anterior facial, region., Three segments of cranium are : occipital segment,, parietal segment and frontal segment., There are four bones in occipital segment, surrounding foramen magnum: supraoccipital (1),, exoccipitals (2) and basioccipital (1)., The skull of rabbit is dicondylic with two occipital, condyles., There are five bones in parietal segment. They are, parietals (2) in the roof, alisphenoids (2) in sides, and basisphenoid (1) in the floor., A depression called “sella turcica” is on the, basisphenoid to lodge pituitary gland., There are five bones in frontal segment. They are, frontals (2) in the roof, orbitosphenoids (2) in sides
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř, , l, l, l, l, l, , l, , l, l, l, , l, l, l, l, l, , l, l, l, l, , l, l, l, l, , and presphenoid (1) in the floor., An ethmoid bone (cribriform plate) perforated with, many small holes closes the cranial cavity in front., Auditory capsule consists of periotic bone and, tympanic bulla., Periotic is a compound bone formed by the fusion, of prootic, epiotic and opisthotic., Periotic is located between squamosal and, occipital ring., Tympanic bulla is a flaskshaped bone applied to, outside of periotic between the basisphenoid and, squamosal., Tympanic bulla encloses tympanic cavity or middle, ear containing tympanic membrane and a chain of, the 3 ear ossicles, which from outside are malleus,, incus and stapes., Stapes is the smallest bone in the body., Ear ossicles are concerned with hearing., Periotic consists of two parts : an internal hard bony, petrous part enclosing internal ear, and a posterior, light and porous mastoid part., Orbits are situated on the sides of frontal segment, of the cranial region., The skull of rabbit is tropibasic, i.e., an interorbital, septum is present., The front wall of each eye orbit contains a small, bone called lachrymal having a notch for tear duct., Facial region consists of bones of olfactory, capsule and jaws., Olfactory capsule consists of nasals in the roof,, vomer in the floor (median formed by the fusion, of two), premaxillae and maxillae at the sides., Mesethmoid or internal septum separates two, nasal chambers., Each olfactory or nasal chamber encloses an, irregular mass of turbinal or scroll bone., Scroll bones help in increasing the sensory surface, of olfactory chamber., The upper jaw consists of the following bones:, premaxilla, maxilla, palatine, pterygoid, squamosal, and jugal., Each ramus of lower jaw is made up of a single dentary., Dentary has a conspicuous condyle, coronoid, process and angular process., Teeth in each dentary are incisor (1), premolars, (2) and molars (3)., The jaw suspensorium in rabbit is craniostylic i.e.,, lower jaw articulates with upper jaw by squamosal., , l, , l, l, l, , l, l, , l, l, , l, l, , l, l, l, l, l, , l, l, , l, , l, , 315, , Main part of the body of hyoid apparatus located, beneath and supporting root of tongue, is called, basihyal., Vertebrae of mammals are acoelous or, amphiplatyan., Total number of vertebrae in rabbit varies from 45, to 47., The vertebral column in divisible into five regions,, namely– cervical, thoracic, lumbar, sacral and, caudal., Vertebral formula of rabbit is C7T1213L67S4Cd16., The first cervical vertebra is atlas. Centrum is, absent. It is articulated to skull through occipital, condyle, zygapophyses are absent. Odontoid fossa, are present., Second cervical is the axis. It has odontoid process., All cervical vertebrae except 7th possess, vertebrarterial canals for the passage of cervical, blood vessels and nerves., In between the centra, there are intervertebral, discs of fibrocartilage., The central portion of the vertebral disc is called, nucleus pulposus which represents the, remnant of notochord in the adult., Sternum of rabbit consists of seven sternebrae, and, a xiphoid cartilage., Sternum is composed of seven rodlike pieces., The first piece is called pre–sternum or, manubrium., Remaining five sternebrae constitute mesosternum, (gladiolus)., This is followed by rodlike last sternebra, metasternum. Metasternum terminates in an, expanded plate of cartilage, the xiphisternal, cartilage or xiphoid cartilage., There are 12 or 13 pairs of thoracic ribs present, in a rabbit., Three types of ribs in rabbit are : true ribs (1st, to 6th pair); false ribs [7, 8 and 9th pair (3 pairs)];, and floating ribs [10, 11 and 12th pairs (3 pairs),, not attached to sternum]., Vertebral rib is bicephalous (with two heads). It is, articulated to thoracic vertebra by tuberculum to, transverse process and by capitulum to centrum., Pectoral girdle of rabbit consists of two bones, a, membranous bone called clavicle and a large, replacing bone called shoulder blade or scapula, coracoid.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 316, , l, l, , l, , l, , l, l, l, l, l, l, , l, l, l, l, l, , l, l, l, l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Dorsal or vertebral edge of scapula is made of a, thin strip of cartilage, the suprascapula., A glenoid cavity for articulation of head of humerus, is present at the tip of scapula and coracoid process., Clavicle is articulated with acromian process., Pelvic girdle of rabbit is Wshaped. Each half, consists of four bones namely ilium, ischium, pubis, and cotyloid., A small cotyloid bone is present on the inner side, of acetabulum between ilium and ischium., , l, l, , l, l, , Cotyloid bone (acetabular bone) is not found in, the pelvic girdle of frog., , l, , In rabbit, a ninth carpal may be present called, pisciform, sesamoid bone., In rabbit, there are five digits in forelimb and four, digits in hindlimb., Digital formula of forelimb is 2, 3, 3, 3, 3., Digital formula of hindlimb is 0, 3, 3, 3, 3., Rabbit has no hallux., Femur is the longest and stoutest bone of the body, in a mammal. Proximally it bears a head, greater, trochanter, lesser trochanter and third trochanter., The proximal end of tibia bears a small sharp ridge, called cnemial crest., Proximal part of humerus bears a slight deltoid, ridge and distally it bears a pulley like trochlea., Above trochlea are present supratrochlear, foramen and olecranon fossa., The digestive system of rabbit consists of, alimentary canal and digestive glands., The various parts of alimentary canal are mouth,, vestibule, buccal cavity, pharynx, oesophagous,, stomach, small intestine, caecum, large intestine, and anus., Dental formula of a rabbit is 2033/1023., Total number of teeth in rabbit is 28., Number of teeth in upper jaw of rabbit is 16 and, 12 in the lower jaw., Rabbit has no canine teeth, it is herbivorous., In rabbit, teeth are heterodont, diphyodont and, thecodont., The mouth of the rabbit is a transverse slitlike, terminal aperture situated at the snout., The mouth opens into a large spacious buccal cavity, between the jaws., The tongue in its dorsal surface bears numerous, papillae containing taste buds., , l, l, , l, l, l, l, l, , l, , l, l, , l, l, , l, , The buccal cavity merges behind into a short, narrow, chamber, the pharynx., A soft palate divides the pharynx into 3 parts as, nasopharynx lies dorsal to the soft palate, the, oropharynx below the soft palate, and both, communicate behind with the laryngopharynx., The floor of laryngopharynx carries a median, verticle slit, the glottis leading into the larynx., Larynx is guarded by a bilobed thin cartilaginous, flap or tissue, the epiglottis., The laryngopharynx leads posteriorly into the, oesophagus through a wide aperture, the gullet., Oesophagous is a long narrow, elastic and muscular, tube. Its inner wall has several longitudinal folds., The stomach is differentiated into three regions:, a broad cardiac region into which oesophagus, opens, a narrow pyloric region which leads into, the duodenum and the third part is situated in, between cardiac and pyloric regions called fundic, region., Small intestine following stomach made of three, parts– duodenum, jejunum and ileum., Large intestine consists of two regions– colon and, rectum., At the junction of ileum and colon a wide about 50, cm long, thin walled tube, the caecum is present., Rectum opens outside through anus, situated at the, base of tail and guarded by anal spincter., Rectum of rabbit is the narrow terminal part with, the faecal pellets present inside which gives it a, beaded appearance., Distally caecum terminates in a small, about 15 cm, long narrow thick walled blind tube, the vermiform, appendix., The caecum is very large and spacious in, herbivores such as rabbit, horse and ass., Caecum of rabbit is thin wall tube with peculiar, external spiral constriction, which marks the, presence of an internal spiral valve., Digestion of cellulose in rabbit takes place in, caecum (stomach in ruminants)., The various salivary gland of rabbit are parotid, gland (situated at the base of pinna),, submandibular gland (situated on the inner side, of the angles of lower jaw); sublingual glands, (situated below the tongue) and infra–orbital, glands (situated below the orbit)., Liver of rabbit is partly divided into 5 lobes : three
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř, , l, , l, , l, , l, , l, , l, l, , l, l, l, l, , l, , l, l, , l, l, l, l, , lobes on left side are a small spigelian, left lateral, and left central, while two lobes on the right side, are caudate and right central or cystic., The cellulose in the diet of rabbit remains, undigested, for which it passes in the caecum. Thus, the digestion of cellulose occurs in the caecum, which is well developed in rabbit and herbivorous, mammals., Cellulose decomposing bacteria and protozoans are, found in the caecum, where it is decomposed to, soluble sugars., Rabbit feeds on night excreta (coprophagy) which, is moist and soft for the digestion of remaining, cellulose., Respiratory system of rabbit consists of nasal, cavity, pharynx, larynx, trachea, bronchi,, bronchioles and alveoli., A cartilaginous partition called mesethmoid, separates the right and left nasal passage or, respiratory passage., The respiratory passage is lined by richly, vascularized, ciliated, mucous secreting epithelium., Respiratory passage performs the function of, warming the air before entering into trachea and, lungs; filtering air etc., Lungs are the sole respiratory surface in rabbit, and are without central cavities., Lung is divided into two lobesright and left lung., Right lung is divided into four lobes while left lung, into two lobes., The larynx or voicebox is the sound producing, organ of rabbit which is a modified anterior part, of the trachea., The larynx leads into the trachea which is a long, tube supported by a series of incomplete rings, of elastic cartilage., The larynx is supported be four cartilages., The largest shieldshaped and most anterior is the, thyroid cartilage which supports the larynx, ventrally and is incomplete dorsally. Just a bit, posterior to it is a ringlike cricoid cartilage which, is broad on the dorsal side but narrow ventrally., A pair of arytenoid cartilages are situated at the, anterior end of the dorsal side of the cricoid., There is also a pair of small nodules the cartilages, of Santorini., Rabbit does not produce audible sound., Trachea is lined with a pseudostratified ciliated, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, l, , l, l, , l, , l, , 317, , epithelium and helps in pushing mucous out., Even there is no air in trachea, it does not, collapse due to presence of Cshaped narrow, cartilaginous rings., Larynx of rabbit acts as a valve for controlling the, movement of air and organ for producing low, pitched sound., The mechanism of breathing consists of intake of, fresh air into the lungs (inspiration) and elimination, of respired air from the lungs (expiration)., Inspiration is an active process during which firstly, the external intercostal muscles contract dragging, the ribs forwards and downwards and the sternum, is moved downwards., Gaseous exchange takes place in the alveoli where, inspired air comes in contact with the blood, capillaries., Oxygen from the air diffuses in the blood and CO2, from the blood diffuses out in the air through the, thin alveolar wall., Expiration is more or less a passive action during, which internal intercostal muscles contract, thereby, the ribs and sternum attain their normal position., Ribs, intercostal muscles and diaphragm are helpful, in pulmonary respiration., The respiratory pigment haemoglobin, present in RBC, of rabbit, plays a pivotal part in the transport of O2, from blood to tissue and of CO2 from tissue to blood., Scroll like bones are present in the cavity of nasal, passage which are called turbinals., There are three such structures called naso, turbinals, ethmoturbinals and maxilloturbinals., In rabbit, there is no sexual difference pertaining, to ventilation movements in male and female as, observed in human., Blood vascular system of rabbit is of closed type., The blood vascular system of rabbit consists of a, circulatory media called the blood, channels, through which the circulatory media flows called, bloodvessels and a central pumping organ, the, heart which pumps the circulatory media in the, blood vessels., The lymph hearts are not found in rabbit,, therefore the lymph flows in the lymph vessels with, the help of body muscles., Mature RBC of rabbit are biconcave, enucleate,, contain haemoglobin and contain antigens on, their plasmalemma.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 318, , l, l, , l, , l, l, , l, , l, , l, l, , l, l, , l, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , RBC have a short life., Fragile, weak, senescent and abnormal RBC are, phagocytised by spleen cells which is aptly called, the ‘grave yard’ of RBC., WBC are nucleated, fewer in number as compared, to RBC, devoid of pigment and are motile (by, pseudopodia)., Heart of rabbit is 4chambered and is enclosed by, a double walled pericardium., The pericardial cavity present between the outer, parietal and inner visceral pericardium is filled with, pericardial fluid and protects the heart from, external shocks, lubricates it to facilitate smooth, systolic and diastolic movement., The heart muscles (=cardiac muscles) are striated, but involuntary. They consists of outer, epicardium, middle myocardium and inner, endocardium., Rabbit does not have sinus venosus which is, incorporated in the wall of right auricle. The, truncus arteriosus is also absent., The two aorta–the pulmonary and systemic arise, directly and separately from the ventricle., The eustachian valve is present between the, openings of 2 precavals and thebesian valve (form, a crescentic fold) bounds the opening of left pre, caval., The ventricles are thickwalled and muscular as, compared to atria., The left ventricle is larger and more muscular, than the right ventricle. This difference is due to, the fact that left ventricle pumps blood to all parts, of the body while the right provides the propulsive, force to drive the blood only to lungs., The longitudinal ridges present on the surface of, ventricle is called columnae carnae which extends, into the ventricular cavity., Papillary muscles are conical muscular projections, on the walls of ventricles., The opening between the right auricle and right, ventricle is guarded by tricuspid (tri = 3, cusp =, flaps) valve, while the one between left auricle and, left ventricle is guarded by bicuspid or mitral valve., The rate of heart beat in rabbit is 210/min. Each, heart beat consists of a contraction (systole) and, relaxation (diastole)., The systole creates the necessary pressure to push, the blood, while diastole facilitates refilling., , l, , l, l, , l, l, l, , l, l, , l, l, l, l, , l, l, , l, , l, , l, l, , In rabbit the oxygenated and deoxygenated blood, flows via different channels (circuits). The blood, during its complete circulation passes through heart, twice and hence this is called double circulation., The blood vessels in rabbit is a system of closed, channels through which blood flows., The wall of blood vessel is typically made of three, layers: tunica externa; tunica media; and tunica, interna., Arteries carry blood away from heart. They are, stronger and thicker than veins., The largest artery in the body is aorta., Both pulmonary artery and renal artery have a thick, muscular coat as compared to the respective, veins., Capillaries are the smallest blood vessels in the, body., Capillary has no muscular wall. Its wall is made, of a single layer of flat endothelial cells and is, consequently very permeable to water and small, solutes, but not to proteins and other, macromolecules., One major difference between an artery and vein, is that vein has a thin muscular wall., Veins contain valves to prevent backflow of blood., Weak valves can lead to varicose veins or, haemorrhoids., All veins carry deoxygenated blood except, pulmonary veins. Pulmonary veins carry pure, blood from lungs back to heart., Renal portal sysem is absent in mammals, only, hepatic portal system is present., Nervous system of rabbit consists of central, nervous system (brain and spinal cord); peripheral, nervous system (cranial and spinal nerves) and, autonomic nervous system (sympathetic and, parasympathetic nervous system)., Brain lies in the cranial cavity of the skull, surrounded by 3 meninges: duramater (outer),, arachnoid (middle) and piamater (inner)., The brain of rabbit can be divided into three regions:, (a) the forebrain (or prosencephalon), (b) the, midbrain (or mesencephalon), and (c) the hind, brain (or rhombencephalon)., Fore brain consists of olfactory lobes, cerebral, hemispheres and diencephalon., Olfactory lobes are responsible for controlling the, organs of smell.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ŐŕőĺŐńŐĹť– ·– ○ňďŚŐŇť– Őě– ○ňĽŇďńř–, l, l, , l, l, l, l, l, l, l, l, , l, l, l, l, , l, l, l, l, l, , l, l, l, l, , l, , The cerebral hemispheres (or telencephalon) are well, developed and form about 2/3 of the whole brain., Corpus callosum is a thick whitish band of, semicircular nerve fibres interconnecting two, cerebral hemispheres (found only in mammals)., Genu is a small front part and splenium is the, posterior part of corpus callosum., Corpus striatum is found in the floor of cerebrum., Diencephalon is a small and narrow posterior part, of the forebrain., Diencephalon is dorsally overlapped by cerebral, hemispheres except for epiphysis or pineal body., Corpus albicans is the swollen part of pituitary, stalk., Midbrain of rabbit consists of four optic lobes, (= corpora quadrigemina)., Optic lobes are solid and optocoels are absent., Crura cerebri or cerebral peduncles are two thick, fibrous white matter tracts on the ventral and lateral, regions of midbrain., Hindbrain includes cerebellum and medulla, oblongata., Cerebellum has five lobes namely a median vermis,, two laterals and two flocculi., The anterior ventral part of cerebellum forms pons, varolii., Arbor vitae is a branched treelike structure, composed of white matter, seen in the section of, cerebellum., Cavity in olfactory lobe is known as rhinocoel., Ventricles I and II are called as paracoels or lateral, ventricles., Ventricle IV is the metacoel., Foramen of Monro connects lateral ventricles with, diocoel., Cavity of midbrain called iter or aqueduct of, Sylvius communicates diocoel with fourth, ventricle of hindbrain., Optocoels are present in frog but absent in rabbit., Formamen of Magendie is the aperture present in, the roof of fourth ventricle or metacoel., Foramina of Luschka are present on the lateral wall, of metacoel., Foramen of Magendie and foramina of Luschka, “three holes” permit cerebrospinal fluid to flow, out into the subarachnoid space from metacoel., The medulla oblongata exits from the skull via, foramen magnum and becomes spinal cord which, , l, l, , l, , l, l, l, l, l, , l, , l, l, , l, , l, , l, , l, , l, l, , 319, , extends to the trunk region of the rabbit., Spinal cord in rabbit extends upto 4th lumbar, vertebra., Filum terminale is the terminal nonnervous part, (made of only piamater) of spinal cord in the lumbar, region., Cauda equina (horsetail) is the taillike collection, of roots of spinal nerves at the posterior end of, spinal cord., In spinal cord, white matter is found outside the, gray matter (reverse in brain)., Internally the spinal cord consists of a neurocoel, which is continuous with the metacoel of brain., Neurocoel is lined by ependymal epithelium, and filled with cerebrospinal fluid., Rabbit has 12 pairs of cranial nerves just like all, other amniote vertebrates (anamniotes have 10 pairs)., These nerves are of 3 types (a) sensory, e.g., olfactory, optic, auditory (b) motor, e.g. oculmotor, and (c) mixed i.e. have both sensory and motor, fibres., Spinal nerves of rabbit arise from spinal cord, (in pairs) and exit via intervertebral foramen, between the vertebra., Each spinal nerve arises from a dorsal root (sensory), and a ventral root (motor)., The spinal nerves in rabbit are 37 pairs which can, be divided into five zones, viz., 8 pairs cervical,, 12 pairs thoracic, 7 pairs lumbar, 4 pairs sacral, and 6 pairs caudal nerves., The autonomic nervous system in mainly, responsible for controlling the involuntary, activities of the body., The sympathetic and parasympathetic nervous, systems work independently but opposite to one, another., Thus each visceral organ is supplied by a, sympathetic fibre which stimulates the organ to, start the function and a parasympathetic fibre, which inhibits and stops the function., Sympathetic preganglionic motor fibres in rabbit, occur only in its thoracic and anterior 3 pairs of, lumbar spinal nerves., Total number of sympathetic ganglia in rabbit is 18, pairs., Sympathetic nervous system increases defence, system of body against adverse conditions. It is, active in stress condition, pain, fear and anger.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 320, , l, , l, l, l, l, , l, , l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Parasympathetic provides relaxation, comfort,, pleasure at the time of rest. It helps in the, restoration and conservation of energy., The hypothalamus controls and integrates the, autonomic nervous system., Sympathetic is accelerator by release of, adrenaline., Parasympathetic is inhibitor by release of, acetylcholine., Rabbit, like all other mammals has a wide variety, of sensory organs which perceive diverse stimuli., The type of receptors are–, –, Tactile (touch) or thigmoreceptor [sensitive, to touch (cutaneous)];, –, Pressure receptor, baroreceptors, (Meissner’s corpuscles);, –, Olfactory sensilla [in nasal epithelium, (Jacobson’s organ)];, –, Gustatory sense organs (taste buds present, on tongue);, –, Sensilla of common chemical sense (detect, deleterious chemicals and when stimulated, give avoidance reaction);, –, Proprioceptor (present in stomach);, –, Pain receptors (present in skin)., In rabbit all cutaneous receptors are naked., Vibroreceptors of rabbit are naked nerve ending, present upon the follicles of vibrissae., The nictitating membrane in rabbit is a vestigeal, structure and is called plica semilunaris., Rabbit exhibit ureotelic excretion i.e. its principal, nitrogenous waste is urea., The urinary or excretory and the genital or, reproductive systems are closely associated with each, other, therefore, these systems are considered together, and collectively known as urinogenital system., The excretory system consists of paired kidney;, paired ureter (which open independently into the, urinary bladder); urethra; and urinogenital, aperture (which acts as common passage for, urine and sperm in male and is present on the, ventral aspect of glans penis. In female the urethra, opens into the vulva)., , l, l, l, l, , l, l, l, l, l, , l, , l, l, , l, l, l, l, l, , Kidney of rabbit is bean shaped, metanephric,, measure 25 mm in length, dark pink in color., The right kidney is usually larger than the left., Both kidney are convex on the outside and concave, on the inner side., A notchlike structure called hilus in present through, which renal artery, nerves; lymphatic channels enter, the substance of the kidney, and the renal vein and, ureter exit., Afferent arteriole carries blood to glomerulus while, efferent arteriole collects blood from it., The diameter of afferent arteriole is much more, than that of efferent arteriole., In nephron Henle’s loop is present to concentrate, the urine., Rabbit manifests sexual dimorphism., Male reproductive system consists of testis, [(= cytogenous gland), scrotal, and site of, spermatogenesis and androgenesis]; epididymis, (tripartite); vas deferens; urethra; penis and, associated male genital glands includes prostate, gland (major contributor of seminal fluid); seminal, vesicles (= uterus masculinus); Cowper’s gland, (=bulbourethral gland); perineal gland; rectal, glands., In rabbit, the testes are migratory i.e. present in, scrotum during breeding season but are pulled up, in abdominal cavity in the nonbreeding state., Testicular sperm of rabbit transit via rete testis and, vasa efferentia into epididymis., Female reproductive system of rabbit consists of, ovaries, fallopian or uterine tubes, vagina,, urethra, vestibule, vulva, accessory reproductive, glands (include bartholin’s, rectal and perineal, glands., Uterus is bicornuate in rabbit., Rabbits are polyestrous mammals., The ovulation is of the reflex (induced) type and, mating is prerequisite for it., Fertilization of ovum is internal and occur in the, upper part of oviduct., Rabbit has well developed endocrine system with, pituitary as master gland.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♣ďŚĚŕ– ☻ĚńŐňř– Őě– ▓ńďňŚř–, , 321, , Chapter 34, , Water Relations of Plants, l, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, , l, , Water is essential for all physiological activities, of plants., Water plays a key role in photosynthesis and acts, as a source of oxygen., Water also plays a direct role in many useful, reactions operating in cells., Water is a major constituent of protoplasm (about, 90%)., Protoplasm has a capacity of retaining its life even, when there is bare minimum of water., If the bare minimum of water decreases protoplasm, cannot restore its life even after the addition of, water., Properties of H2O : Water has high specific heat,, latent heat of evaporisation, adhesive force,, cohesive force and high surface tension., Two hydrogen atoms are attached to the atom of O2, at an angle of 1050., Water is an universal solvent., Water is useful for maintaining the turgidity of, cells which is essential for cell enlargement,, growth and the form of herbs., Water is a reactant in many biochemical reactions., Dispersal of fruits, seeds, spores and mobility of, gametes depends upon by water., Water is used to regulate the heat in plants, through transpiration, guttation, evaporation., , DIFFUSION, IMBIBITION, OSMOSIS, l, , l, , l, , Physical processes associated with water relations, of plants are : diffusion, imbibition, and osmosis., The movement of ions, atoms or molecules from, a region of higher concentration to a region of lower, concentration is called diffusion., Diffusion cannot occur between two solids., , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , Solutions are formed by diffusion of solute in a, solvent., When alcohol and water are mixed water diffuses, into alcohol and alcohol diffuses into water., When O2 and CO2 are mixed O2 diffuses into CO2, and CO2 diffuses into O2., A plant cells has three physiological, compartment cell wall, protoplast and central, vacuole., Two membranes separate these three, compartements, tonoplast around central vacuole, and plasmalemma around protoplast but below the, cell wall. Both are selectively permeable., Central vacuole contains an osmotically active fluid, called cell sap., Diffusion processes involved in plants are , –, Passive absorption of ions, –, Entry of ions into apoplast, –, Liberation of water vapour through stomata, –, Exchange of gases through stomata, –, Entry of water from the cell wall into the cell., Apoplast is the system of cell walls extending, through a plant body and along which water, containing mineral salts, etc. can move passively., It is an important pathway for movement of, these substances outside the xylem., Symplast is the living system of interconnected, protoplasts extending through a plant body., The process of increase of the volume of a solid, due to absorption of water by hydrophilic colloids, is called imbibition., Increase of a solid is due to absorption of water, by hydrophilic colloids (imbibants) such as proteins,, cellulose, starch etc., Imbibition involves three important
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 322, , l, , l, , l, , l, l, , l, , l, l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , characteristics : volume change, heat production, and pressure development., As the water molecules are arranged on the surface, in the process of imbibition, they lose some of, their kinetic energy which then appear as the heat, in the system., The substance which shows imbibition is called, imbibant and the pressure created by imbibant is, called imbibitional pressure., Wooden pieces of doors and windows become tight, during rainy season due to the process of, imbibition., Rubber does not show imbibition., Imbibition processes in plants are exhibited by the, following – (i) raisins, (ii) dry seeds, (iii) cell, walls, (iv) velamen roots, (v) dry lichens etc., Significance of imbibition –, –, It is the dominant and first step of water, absorption., –, Imbibition is the first step in germination of, seeds, i.e., first imbibition occurs by seed coat, and then by embryo and other parts., The term osmosis was coined by Abby Nollet, (1978)., Osmosis is the diffusion of water from its pure, state into a solution when the two are separated by, semipermeable membrane or it is the diffusion of, water or solvent from a dilute solution to a strong, solution through a semipermeable membrane., A solution which can cause an osmotic entry of, water into it is said to be osmotically active, solution., Membrane which allows diffusion of both solvent, and solute molecules and ions through it, is called, permeable membrane, eg. cellulose wall of cells., Membranes which do not allow diffusion of, both solvent and solute particles through, them are called impermeable membranes,, eg. suberised cell walls in plants., Membranes which allow some solutes to pass, through them along with the solvent molecules, using different mechanisms, are called, differentially permeable membrane, eg. Plasma, membrane, tonoplast and membrane surrounding, cell organelles., Semipermeable membranes allow diffusion of, , l, l, , l, l, , l, l, , l, , l, l, , l, , l, l, l, l, l, , solvent molecules but do not allow the passage, of solute molecules., Egg membrane is a semipermeable membrane., Semipermeable membranes prepared in the, laboratory are collodian, cellophane, parchment, paper, etc., Semipermeable membrane is permeable to ions of, salt but not to the sugar molecules., Common experiment to demonstrate osmosis is, thistle funnel experiment., Experiment useful for demonstrating osmosis by, using a living tissue is potato osmoscope., Osmosis in plants helps in –, –, Absorption of water, –, Maintaining turgidity and expansion of cell, –, Movement of water, –, Opening and closing of stomata., Reverse osmosis is expulsion of pure water from, a solution through a semipermeable membrane, under the influence of external pressure higher than, O.P. of solution., Reverse osmosis is used in removing salts from, saline water as well as extrapurification of water., Signification of osmosis are –, –, Osmosis is responsible for absorption of water, by roots., –, Osmosis is responsible for turgidity of plant, organs., –, Osmosis is responsible for cell to cell, movement of water., –, It is responsible for opening & closing of, stomata., –, It is responsible for resistance of plant to, drought, frost, etc., Factors controlling osmosis are –, –, Presence of a perfectly semipermeable, membrane is a must for the operation of osmosis., –, Concentration of dissolved solute on the two, sides of semipermeable membrane., Pressure required to prevent the entry of water into, a solution is called osmotic pressure., The term osmotic pressure was proposed by Pfeffer., Osmotic pressure is a positive value., Pure solvent has no osmotic pressure., When solute is added to pure solvent it develops, osmotic pressure.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♣ďŚĚŕ– ☻ĚńŐňř– Őě– ▓ńďňŚř–, l, , l, l, l, l, , l, l, , l, , l, l, l, , l, l, l, l, , l, l, l, l, , Osmotic pressure (O.P.) can be calculated by, OP – CRT, where C is molar concentration of, solution, R is gas constant and T is absolute, concentration., The value of osmotic pressure is related to number, of particles and not molecules., In nonelectrolytes the number of particles and, number of molecules is same., In electrolytes (eg. NaCl) number of particles (or, ions) is more than the number of molecules., Osmotic pressure value of solution of ionising, substance will be greater than osmotic pressure of, solution of nonionising substance though their, concentrations are same., Pressure exerted by diffusing ions or molecules is, called diffusion pressure., Diffusion pressure is the pressure exerted by a, substance due to tendency of its particles to diffuse., It is also called suction pressure (S.P.), the pressure, with which water enters into a cell., Diffusion pressure deficit (D.P.D) is the reduction, in the diffusion pressure of water over its pure, state., Diffusion pressure of a pure solvent is maximum, and it decreases with the addition of solute., Water moves from a system with low D.P.D. to a, system with high D.P.D., When water diffuses into a cell through the process, of osmosis the cell becomes swollen, thus swollen, cell is called turgid cell., A system have two or more types of diffusing, particles, eg., oxygen and carbon dioxide., Each diffusing substance exerts its own diffusion, pressure called partial diffusion., Particles of different substances diffuse according, to their own partial pressure., Tendency of different substances to diffuse, according to their own partial pressures or, concentrations is known as independent diffusion., Outward pressure exerted by plasma membrane on, the cell wall is called turgor pressure., Inward pressure exerted by cell wall on the plasma, membrane is called wall pressure., The values of turgor pressure and wall pressure are, equal., In a flaccid cell suction pressure is equal to, osmotic pressure., , l, l, , l, , l, , l, , l, , l, l, l, l, , l, l, l, , l, l, l, l, l, , l, , 323, , Suction pressure in a turgid cell and turgor pressure, in a flaccid cell is zero., In a turgid cell osmotic pressure is equal to turgor, pressure., When water moves along the energy gradient free, energy is liberated. The amount of energy liberated, from a substance when its potential energy is, converted into kinetic energy is called free energy., Free energy present in 1 mole of a substance, (Avogadro no. of substance 6.023 × 1023) is called, chemical potential., Chemical potential of water is called water, potential., The term water potential is used in the place of, D.P.D. and SP. The difference between free energy, of water in a system and free energy of pure water, at atmospheric pressure is also called water, potential., The term water potential was proposed by Slatyer, and Taylor., Symbol of water potential is y., Water potential of pure water is zero., When a solute is added to pure water, water, potential of solution decreases and is expressed, in –ve values., Water potential is measured in bars. 1 bar = 0.998, atm (0.987 atm) or 106 dynes/cm2., The difference between water potentials of two, solutions is expressed as DyW ., lf y W value of cell A is 2 bars and y W value of, cell B is 10 bars water diffuses into B cell., Therefore water moves from a system with a high, water potential to a system with low water, potential., Potential required for the entry of water into a, solution is called osmotic potential., Osmotic potential has a –ve value and its symbol, is yp (ys)., The symbol for pressure potential is y P., Pressure potential is used in the place of turgor, pressure., The relation between water potential, osmotic, potential and pressure potential can be, represented as : yW = yp + yP., Entry of water into a cell through a plasma, membrane is called endosmosis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 324, , l, l, l, , l, , l, l, l, , l, l, l, , l, l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Exit of water from a cell through a plasma, membrane is called exosmosis., Solution that has the same osmotic concentration, as that of another solution is called isotonic., Solution having an osmotic concentration lower, than that of another solution is called hypotonic, solution., Solution which has an osmotic concentration higher, than that of another solution is called hypertonic, solution., If a cell is placed in hypotonic solution endosmosis, takes place., If a cell is placed in hypertonic solution exosmosis, takes place., If a cell is placed in isotonic solution no changes, occur which means that number of molecules, entering into cell is equal to number coming out., Shrinkage of plasma membrane or protoplast from, the cell wall due to exosmosis is called plasmolysis., The cell showing plasmolysis is called plasmolysed, cell., In a plasmolysed cell turgor pressure is zero and, space between cell wall and plasma membrane is, occupied by hypertonic solution., Cell wall is permeable to solution., Stage at which plasma membrane or protoplast, showing starting of shrinkage is called incipient, plasmolysis., When a plasmolysed cell is placed in a, hypotonic solution endosmosis takes place and this, phenomenon is called deplasmolysis., Lower epidermal cells of Tradescantia leaves are, generally used for the demonstration of plasmolysis, because their cells contain anthocyanin pigments., Saprohytic bacteria or fungi cannot survive on, salted dishes due to plasmolysis., Weeds are killed by adding salt. The principle, involved is plasmolysis., , l, , l, l, l, l, l, , l, , l, l, l, l, , l, l, l, l, l, l, l, , ABSORPTION OF WATER AND ASCENT, OF SAP, , l, , Land plant absorb water mainly from the soil., For this the roots must be metabotically active,, respiring and continuously growing., Roots are usually restricted to that area of soil which, lies well above the water table., , l, , l, l, l, , Soil has several types of water capillary,, gravitational, hygroscopic, combined and water, vapours., The chief source of water to the soil is rain., Other sources of water to the soil are water table,, melting of snow or ice and irrigation of fields., Water table is the depth at which the earth crust, is saturated with water., The total amount of water present in the soil is, called holard., Available water to the plant is called chesard and, water which is not available to plant is called, echard., The capillary water is readily available to the plants, and it is the main source of practically all the water, absorbed by plants., Field capacity is the maximum amount of water, a soil can hold after gravitational flow has stopped., Water beyond field capacity causes waterlogging., Water logging reduces soil oxygen and decreases, water absorption., Under water logging conditions the soil air is, expelled out and plants fail to survive due to, deficiency of air in the soil., If the amount of water in the soil is less than field, capacity, the plants show symptoms of wilting., Water is absorbed by plants in small quantity in, the saturated atmosphere., Most of the water absorption occurs through roots, from the soil., Plants absorb all gases and nutrients which are, dissolved in water., Region of root useful for absorption of water is, root hair region or piliferous zone., Structures useful for absorption of water in, piliferous zone are root hairs., Root hairs serve to increase the area of contact, between the root surface and soil., Kramer recognized two distinct mechanisms which, independently operate in the absorption of water, plants., Two mechanisms of water absorption are –, –, Active absorption – Water is absorbed by, the roots i.e. roots takes part actively in, absorption and the pressure responsible for, absorption develops in roots itself.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 325, , ♣ďŚĚŕ– ☻ĚńŐňř– Őě– ▓ńďňŚř, , Passive absorption – Water is absorbed, through the roots i.e. the roots are passively, involved in the absorption. The pressure, responsible for pull of water develops in the, shoot., Absorption of water due to activity of root itself is, called active absorption., Cell sap of root hair usually possesses higher OP, (2 8 atm) compared to OP of soil water, (< 1 atm)., Water always moves according to the potential, gradient., Soil water with high potential gradient moves, into root, stem, leaf and finally reaches, atmosphere having low potential gradient, in the, form of water vapour., Active absorption takes place according to the, principle of osmosis and it requires energy., (According to Renner, active absorption of water, occurs in the absence of transpiration.), Osmotic theory of active absorption was proposed, by Atkins and Priestly., Osmotic theory of active water absorption states, that entry of solute as well as water at the surface, of cell membrane takes place due to imbibition by, cell wall of root hairs., –, , l, l, , l, l, , l, , l, l, , Principle involved in osmotic theory, of active water absorption, High O.P. and low T.P. in root hairs, , l, l, l, l, l, , Loss of water in mesophyll cells due to transpiration, causes, Decrease in T.P.and hence increase in D.P.D, causes, Water absorption by mesophyll, from adjacent xylem cells, This creates transpiration pull, This pull is transmitted downwards upto roots, which is, Removed after absorption of water from soil, l, , l, , causes, , Increase in D.P.D. (in root hairs), results in, , l, l, , Endosmosis, Absorption of water by root hair, , l, , results in, , Increase T.P. and thus D.P.D. is decreased, in root hair with respect to adjacent cell, Same process, i.e. , Increase in T.P. and decrease, in D.P.D. occurs in the cells of intermediate, channels like cortex, endodermis etc., , l, , l, , thus, , Water finally reaches to xylem, l, , l, , Absorption of water against concentration gradient, utilising respiratory energy is nonosmotic theory, of active water absorption., The factors such as low temperature, poor O2 supply, , etc. reduces the rate of respiration and water, absorption., Auxin increases the rate of respiration as well as, water absorption., Absorption of water due to pressure developed in, shoot is called passive absorption., Passive absorption of water is due to transpiration, pull., Passive absorption of water was proposed by, Kramer and Lachenmeir., The theory of passive absorption works on the, following principle., , l, , Movement of water from root hairs to the xylem, vessels through cortical cells is called lateral or, radial conduction of water., This movement of water occurs according to the, osmotic potential gradient., Plant absorbs water between field capacity and, permanent wilting percentage., If loss of water from aerial parts of a plant, (transpiration) exceeds the rate of absorption, plant, wilts., The partial loss of turgidity which does not cause, visible wilting is known as incipient wilting., If plants fails to regain their original stage due to, general loss of turgor, stage represents permanent, wilting., In herbaceous plant during summer season, plant, wilt during hot days and regain their turgidity and, freshness during night, the type of wilting is called, as temporary wilting., Wilting is observed usually in those plants in which, tissues are made up of thin walled. Parenchymatous, cells are responsible for maintaining the turgidity, in plants.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 326, , l, , l, , l, l, l, , l, l, l, , l, , l, , l, , l, , l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Permanent wilting percentage (PWP) is the, percentage of water on the dry weight basis of the, soil that is present in the soil when the plants, growing in it fresh, touch the condition of, permanent wilting., This value varies between 1–15% and depends upon, the texture of soil, e.g., clay has higher PWP than, sand., No water is absorbed below permanent wilting, percentage or wilting coefficient., No water is absorbed in frozen soil as frozen soil, is impermeable for water., Rate of water absorption decreases below 20°C, because of increased viscosity of water, decreased, permeability of membrane, poor root growth, and low metabolic rate., Water is generally absorbed when concentration, of root hair cell sap is more than outer soil water., Upward movement of water (sap) through xylem, against the force of gravity is called ascent of sap., Ringing experiments were proposed by Malpighi, and Stephen Hales to demonstrate that ascent of, sap takes place through xylem vessels., Types of theories to explain ascent of sap are –, vital theories, rootpressure theory and physical, theories., Theories which consider the living cells responsible, for ascent of sap are vital theories, eg. relay pump, theory, pulsation theory etc., Scientists who proposed vital theories are , Godlewski, Mac Dougel and Jagadish Chandra, Bose., According to relay pump theory (clambering, theory) proposed by Godlewski (1883), ascent of, sap takes place due to rhythmic changes of O.P of, xylem parenchyma cells., Pulsation theory was proposed by J.C. Bose,, (1923)., The plant used by J.C. Bose is Desmodium gyrans., According to pulsation theory ascent of sap takes, place due to the pulsating activity of living cells, of innermost layers of cortex., Ascent of sap occurred even after killing the living, tissues with picric acid and cyanides. This was, reported by Strasburger (1891) and thus discarded, vital theories., The term root pressure was coined by Stephen, Hales., , l, , l, l, l, l, , l, l, l, , l, l, l, l, , l, l, l, l, l, , l, l, , l, , A positive hydrostatic pressure developed in roots, due to accumulation of absorbed water is called, root pressure. This theory was proposed by, Priestley (1916)., Root pressure can be measured by manometer., Maximum root pressure in plants will be around 2, 3 bars (0.2 0.3 MP). 1 MP = 10 bars., Root pressure theory explains mechanism of, ascent of sap in herbs., Root pressure theory is not acceptable because root, pressure is absent in gymnosperms and actively, transpiring plants, though ascent of sap occurs in, them., Ascent of sap also takes place after the removal of, root system (reported by Strasburger)., Root pressure exhibits negative tension., Water drops formed at the margins of leaves of, grasses after humid warm nights are the best, evidence of root pressure., The exudation of water in the form of liquid from, the aerial parts of a plant is called guttation., In Saxifraga guttation is more during flowering, season., Cavitation is the formation of water vapour pocket,, which puts a "break" in chain and stops flow., Theories which consider the physical forces are, responsible for ascent of sap are called physical, theories., Capillary theory (1874) was put forward by Bohm, (1863)., Unger (1869) and Sachs (1874) proposed, imbibition theory., Dixon and Jolly (1894) proposed cohesiontension, theory., Cohesiontension theory is widely accepted, physical theory for ascent of sap., Main principles involved in ascent of sap are –, –, Adhesive forces of water, –, Cohesive forces of water, –, Transpiration pull., Backbone of cohesiontension theory is, high surface tension of water., Surface energy of water is available to surface films, of water. As a result water molecules are adhered, to the innerwalls of xylem vessels., Water molecules are attached to one another due to, their cohesive forces (cohesion). As a result water, column is formed in xylem vessels.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 327, , ♣ďŚĚŕ– ☻ĚńŐňř– Őě– ▓ńďňŚř–, l, , l, , l, , l, , l, , l, , l, , l, , l, , Water column extends upto the vein endings of, leaves., Main force useful for ascent of sap is transpiration, pull., Wall surfaces of mesophyll cells lose water thereby, water potential decreases in mesophyll cells., Water potential gradient is established between, mesophyll cells and xylem vessels of root., Transpiration pull is a force developed in, mesophyll cells due to transpiration., Tens ion developed in mesoph yll cells is, transmitted to the root system through xylem, vessels. Due to this tension developed in the, mesophyll cell water volume is pulled to the upper, part of the plant., If concentration of soil water is high due to, dissolved salts (saline soil), there are chances of, exosmosis. Such soils are called physiologically, dry soils., Absorption of water proceeds more rapidly in well, aerated soil as compared to those which are not., In poorly aerated soil root growth is poor and thus, water absorption is low., In poorly aerated soil, O2 concentration reduces, and CO2 increases. If O2 concentration in soil is, low, rate of respiration of root cells is reduced, and thus influence (reduces) metabolic activity., Reduced metabolic activity causes poor root, growth and hence low absorption of water., Poorly aerated soil, , Vi s c o s i t y i s, d i r e c t l y, proportional to, Lack of O2 increase in CO2, density. As CO2, Why ? is denser than, Increase in viscosity, O2, hence, increase in CO2, The density of, system and hence, increases, viscosity of water, v is c o s it y o f, increases, water., Decrease in, Higher the viscosity, Why ?, permeability, denser will be the, liq uid and hence, lower will be the, Poor root growth, pe rmeability of, membrane for it., Low water absorption, , l, , l, , l, , l, , l, , l, , In poorly aerated soil, water is absorbed slowly, also because of increased viscosity of water and, poor permeability of membrane., When transpiration is low, the root has to take, part actively in absorption. Thus slowly transpiring, plants show active absorption., When transpiration is high, th e tens ion, developed in mesophyll cells pull water upwards., There, roots do not play any significant role rather, work as mere intermediate channel in water, absorption. Thus rapidly transpiring plants show, passive absorption., The aerial roots of epiphytic roots have specialized, tissue (velamen) for absorbing rain water and, condensed water vapours., Soil plant atmosphere continnum (SPAC) is the, pathway for water moving from soil through the, plant to the atmosphere., The transport of water along this pathway occurs, in separate components, defined differently between, three scientific disciplines of the environment., , TRANSPIRATION, l, , l, , l, , l, , l, , l, , l, , l, , The loss of absorbed water in the form of vapours, from the living tissue of aerial parts of the plant is, termed as transpiration., A very small fraction of water absorbed by plant, (generally less than 5%) is utilized in plant, development and metabolic processes and the, remaining is lost in the process of transpiration,, It is also estimated that loss of water from a forest, is about 36,400 litres per acre per day., A corn plant may transpire upto 54 gallons of, water in one growing season (which equals to about, 100 times of its own weight)., From a deciduous forest, during one complete year, the, water loss can be equal to 30% of rainfall of the area., In a crop, 90 to 500 kg of water is lost for the, production of 1 kg of dry matter., Transpiration ratio or water requirement or, efficiency of transpiration is the amount of water, transpired by a plant for the synthesis of a unit dry, matter., Transpiration ratio gives an idea of the requirement, of water/irrigation by crops, shrubs and trees.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 328, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Transpiration is useful for passive absorption of, water., Transpiration is responsible for mass flow or bulk, flow of mineral along with water., The pressure developed by transpiration is, responsible for ascent of sap., It is useful for temperature regulation in plants, because heat is removed by transpiration., Water deficit formed due to transpiration leads to, wilting and injury in plants., Some chemicals when sprayed on leaves reduce, the rate of transpiration. Such substances are called, antitranspirants., Antitranspirants are of two types metabolic, inhibitors and surface films., Metabolic inhibitors reduce transpiration by, reducing the stomatal opening for a period of two, or more weeks without influencing other metabolic, processs. The most promising of these inhibitor is, phenyl mercuric acetate (PMA, 10–4 M). Another, is abscissic acid (ABA)., Film forming chemical check transpiration by, forming a thin film on the transpiring surface. They, are sufficiently permeable to carbon dioxide and, oxygen to allow photosynthesis and respiration but, prevent movement of water vapours through them., The important chemicals of this group are silicon, emulsions, colourless plastic resins and low, viscosity waxes., When crop plants are suffering from water deficit,, antitranspirants are given as foliar spray., Common experiment used to demonstrate, transpiration is bell jar experiment., Chemical used in transpiration experiments is, cobalt chloride., The diagramatic representation of the size of stoma, at different times of the day is stomatal clock, (prepared by Von Mohl)., Potometer is an instrument for measuring the rate, of transpiration by shoots by measuring the rate of, their water absorption., Porometer is an instrument for measuring the, degree of stomatal opening., Psychrometer is an instrument for measuring both, the relative humidity and transpiration., , l, , Tensiometer is an instrument used for measuring, soilwater tension., , Types of transpiration, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Transpiration is of four types : cuticular, stomatal, lenticular and bark transpiration., Cuticular transpiration is the loss of water in, vapour form from the general surface (leaves and, young stems) through the layer of cuticle., Cuticular transpiration continues throughout the, day and night. About 10% of water is lost by this, type of transpiration., Stomatal transpiration is the loss of water in the, vapour form from stomata present on the surface, of leaves and to a lesser extent from the surface of, flowers and young stems (cauline transpiration)., Stomatal transpiration occurs only when stomata, are open. About 90% of the total transpiration, occurs through stomata., Transpiration which occurs through stomata of, leaves is called foliar transpiration., Lenticular transpiration occurs through the, lenticles which are small regions on bark and bears, small loosely arranged cells called complementary, cells. Negligible amount of water is lost through, lenticular transpiration., Lenticular transpiration is the main method of, water loss from deciduous trees after leaf fall., Lenticular transpiration continues throughout day, and night., A very small quantity (0.17%) of water is lost from, the corky bark of the stem. It is known as bark, transpiration., Mayor (1956) has reported that some of the, herbaceous plants, under favourable conditions,, transpire the entire volume of water which a plant, has and it is replaced within a single day., , Stomata, l, , l, , l, , Stem and leaf epidermis are provided with, numerous pores called stomata. The number of, stomata per sq. cm of leaf epidermis is variable., Stomata are meant for gaseous exchange during, photosynthesis and respiration but also the main, source of transpiration., Stomata consists of two guard cells, which are
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 329, , ♣ďŚĚŕ– ☻ĚńŐňř– Őě– ▓ńďňŚř–, , l, , l, , generally bean shaped or kidney shaped, but in, grasses they are dumbell shaped., The guard cell usually measured 45 × 15 micron, in size and they cover just 1 2% of total leaf area., Stomatal width increases when they are close., Type of, plant, , Type of, stomata, , Location of, stomata, , Apple, and Hypostomatous On the lower surface, mulberry type, of leaf, eg, apple,, peach, Potato type, Amphistomatous On both surface of, leaf but numerous, on the lower surface,, e.g. potato, bean., Oat type, Isostomatous, Equally distributed, on both the surfaces, of leaf, eg. wheat,, rice, potato, bean., Waterlily type Epistomatous Only on the upper, surface of leaf., These are found in, plants with floating, leaves., Pot a mog e ton Astomatous, Either absent or non, type, functional. This is, characteristic feature, of submerged hydr, ophytes., l, , They enclose a tiny opening called stomatal pore, or stoma., Type of stomata, , Nature of stomata, , 1. Barley or cereal, type (dumbbell, shaped), eg. maize,, wheat., , Open for a few hours, during the day., , 2. In Alfafa or, leucerne type, eg., pea, bean, grape, , Remain open, throughout the day,, close at night., , 3. In Potato type, eg., potato, Cucurbita,, bananas, , Open throughout day, and night but close for, a few hours in case of, water deficiency., , 4. In Equisetum type,, eg emergent, hydrophytes, , Remain open and, seldom close., , l, , l, l, l, , l, , l, , l, , l, , l, , The term stomatal apparatus is then applied to the, opening as well as guard cells and guard cells may, be surrounded by varying number of specialised, epidermal cells called subsidiary or accessory cells., Stomatal opening depends upon availability of, K+ ions from adjacent epidermal cells., A number of other minerals are also essential for, stomatal movemets, e.g., P, N, Mg, Ca, etc., When guard cells are fully turgid, stoma opens., When guard cells are in flaccid state, stomata, closes., Based on stomatal distribution, plants are divided, into categories apple and mulberry type, potato, type, oat type, water lily type, potamogeton type., Depending upon the periods of opening and closing, stomata are of four types as given below., Main theories about the mechanism of stomatal, movement are –, –, Guard cell photosynthesis theory Given, by Schwendener (1881) and also hinted by, Von Mohl (1856)., –, Starch hydrolysis theory First given by, Llyod. Formulated by J.D. Sayre (1923) and, modified by Steward (1964)., –, Malate or K + ion pump hypothesis , Proposed by Levitt (1974) and elaborated by, Raschke (1975) and Bowling (1976)., In night guard cells become flaccid in absence of, sugar which is only formed by photosynthesis and, stomata become closed., Guard cell photosynthesis theory may be, represented as –, Chloroplast in guard cells, Photosynthesis in day time, Formation of sugar in guard cells, Osmotic concentration in guard cell increases, Induces water absorption from adjacent cells, Guard cells turgid, Stomata open
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 330, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Objections to guard cell photosynthesis theory, are –, –, Photosynthetic activity of the guard cell, chloroplasts is not confirmed., –, Sugar does not occur in detectable quantity in, the guard cells., –, In some plants stomata open during night., According to Llyod (1908), the conversion of, starch into sugar in the day time and vice versa, at night causes opening & closing of stomata., Sayre (1926), Scarth (1932) suggested that this, conversion is controlled only by pH of the, guard cells whereas Steward (1964), regards, that this is partly enzymatic and partly controlled, by pH., Starchhydrolysis theory may be represented as, In day time, In dark, CO2 of intercellular, spaces, photosynthesis, Starch, H+ concentration, lowers and enzyme, phosphorylase activates, Glucose1phosphate, phosphoglucomutase, , OP & OPD of guard, cell increase, , Starch, , OP & OPD of cell, sap decreased, , l, , Hydrolysis of starch, PEP, PEPcase, , Stomata close, , Objection of starchhydrolysis theory are –, –, Glucose does not occur in detectable quantity, in the guard cells of open stomata., sugar interconversion is too slow, –, Starch, to account for rapid stomatal opening and, closing., According to Levitt (1974), opening and closing, , CO2, , OAA, Malic acid in, guard cells, H+ + malate ions, +, K ion exchange, from subsidiary cells, +, K + malate ion, Osmotic pressure of, guard cells increase, Endosmosis, , During night time, , CO2 conc. increases in, substomatal cavity, ABA participation, K ion exchange, stopped, +, , K ion back into, subsidiary cells, +, , pH decreased, Synthesis of starch, Osmotic pressure, decreases, Exosmosis, Stomata close, , Stomata open, l, , l, , l, l, , Stomata open, l, , Rise in pH, , l, , Water absorption by guard Guard cell become, flaccid, cells from adjacent cells, Guard cell become, turgid and swell, , During daytime, , Glucose, pH decrease due, to accumulation of, CO2 in substomatal, cavity, Glucose 1 phosphate, , Glucose6phosphate, phosphate, Glucose + phosphate, , l, , of stomata is controlled by active K+ transport and, pH of guard cells., Theory of K+ transport and hormonal regulation, may be represented as –, , Scotoactive stomata are stomata which open in, dark and close during daytime. These occur in, succulents., Both red and blue lights stimulates stomatal, opening though blue light is slightly more effective., In dry weather, stomata tend to close while in humid, environment they remain open for longer period., Rise in temperature induces stomatal opening and, viceversa., At 38° 40°, stomata open even in dark., , Factors affecting transpiration, l, , l, l, l, , Transpiration is directly proportional to the light, intensity, temperature, wind velocity, leaf surface, area, rootshoot ratio, number of stomata., Transpiration is inversely proportional to CO2, concentration and atmospheric humidity., Low carbon dioxide concentration induces, stomatal opening and viceversa., Increase in carbon dioxide causes stomatal closure, hence reduce transpiration.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 331, , ♣ďŚĚŕ– ☻ĚńŐňř– Őě– ▓ńďňŚř, , External factors, l, Light – Light increases transpiration through, opening of stomata and increased protoplasmic, permeability., l, Temperature – The temperature of the leaf is slightly, higher than the environment. Increase in, temperature brings about an increase in vapour, pressure gradient thus increases transpiration., For eg., at 30°C a leaf may transpire three times, as fast as it does at 20°C., l, Humidity – Increase in humidity decreases, transpiration & viceversa., l, Atmospheric pressure – The rate of transpiration is, inversely proportional to atmospheric pressure., l, Availability of soil water – Transpiration is directly, influenced by availability of water. Reduced, availability of soil water causes wilting or loss of, turgidity resulting in drooping & rolling., l, Wind velocity – Wind has an significant effect on, transpiration. Air movement increases the rate of, transpiration by bringing dry air and removing moist, air around the transpiring material. High velocity, wind, however, closes stomata., Internal factors, l, Structure of leaves – Thick cuticle, waxy coating, on leaves, sunken stomata, covering of dead hairs, on leaves decreases transpiration, therefore these, adaptation are found in xerophytes. Reduced leaf, area reduces the rate of transpiration as in, succulents. (cacti or euphorbias). Plants possessing, broad leaves show high rate of transpiration (due, to increase surface area) and viceversa., l, Rootshoot ratio – The roots absorbs water and the, leaves transpire. If the rate of absorption becomes, slower than transpiration, the latter is also decreased, correspondingly. According to Parker, 1949 the, transpiration increases with the increase of root, shoot ratio., l, Stomatal frequency – The rate of transpiration is, directly proportional to the stomatal frequency (no., of stomata per unit of leaf area). Rate of, transpiration will be high in leaves having more, stomata per unit area., , Significance of transpiration, l, l, l, l, l, , l, , l, , It controls the rate of absorption of water from soil., It helps in absorption of mineral salts., It is responsible for ascent of sap., It regulates the plant temperature by contributing, to cooling of leaves and also the surroundings., It protects the leaves from heat injury, particularly, under conditions of high temperature and intense, sunlight., Transpiration causes loss of huge amount of water, absorbed by plants. Also water deficit formed due, to transpiration leads to wilting and injury in plants., It often produces water deficit in plant which check, photosynthesis, reduces growth and if too severe, may cause death from dessication., Inspite of various disadvantages the plant cannot, avoid transpiration due to their peculiar structure, of leaves which is basically meant for gaseous, exchange during respiration and photosynthesis., Therefore transpiration is also regarded as, “necessary evil” by Curtis (1926) or “unavoidable, evil” by Steward (1959)., , GUTTATION, l, l, l, l, , l, l, , l, , Loss of water as droplets from the tips and margins, of leaves is called guttation., The term guttation was coined by Bergerstein., Guttation takes place through hydathodes and the, motivative force is root pressure., Hydathodes are stomata like pores generally, present at the tip or margins of leaves of those, plants that grow in moist shady places. (e.g.,, Tropaeolum)., Pores are present over a mass of loosely arranged, cells with large intercellular spaces called epithem., For this the roots must be metabolically active,, respiring and continuously growing., Th e term blee ding simp ly means a s low, exudation of water sap from a cut or injured, part of plant., The exudation of latex in the para rubber tree is the, best example of this type.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 332, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 35, , Mineral Nutrition in Plants, TYPES OF NUTRITION, l, , l, l, , l, , l, , l, , l, , l, l, l, , l, , l, , A large number of substances are required from, outside for completion of life cycle normally and, efficiently., The chemical substances that provide nourishment, to living organisms are called nutrients., Nutrition is the process that involves the absorption, of various mineral ions by the plants for their growth, and development., Except for hydrogen, carbon and oxygen which, constitutes about 90 percent of dry weight, all other, inorganic plant requirements are obtained from soil., It is well known that the yield of a crop depends, upon the mineral constitution of the soil. As the, sources of these inorganic requirements are, minerals, the elements are called mineral nutrients, and thus nutrition is known as mineral nutrition., Many of them are represented as a part of structural, organic compounds, e.g., nitrogen, phosphorous,, sulphur and calcium. Nitrogen and sulphur are taken, up in the inorganic form and converted into organic, molecules as amino acids., A nutrient can be simple or complex organic, molecule called organic nutrient or a mineral ion,, called inorganic nutrient., CO2 is an inorganic nutrient for plants., Protein component of our diet is organic nutrient, for human being., Plant nutrition is mainly of two types :, autotrophic nutrition and heterotrophic, nutrition., Autotrophic nutrition is the type of nutrition where, organism manufacture their own food from simple, inorganic raw material., Autotrophs can be photoautotrophs (obtain energy, from solar radiation) or chemoautotrophs (obtain, energy from chemicals)., , l, , l, , l, , l, , l, l, l, l, , l, l, , l, , Heterotrophs are those organism which fail to, synthesize their own organic nutrients from, inorganic substances and depend on other sources, for food. e.g. some bacteria, fungi, bryophytes,, pteridophytes and angiosperms., This type of nutrition is called special in case of, angiosperm because generally angiosperms are, chlorophyllous and manufacture their own food., Heterotrophic plants are broadly classified into, three categories depending upon the source from, which they obtain food saprophytes, parasites, and insectivores., Saprophytes live upon dead organic matter and, are responsible for conversion of complex organic, substance into simple inorganic substances. E.g, –, Algae Polytoma, –, Bryophyte Buxbaumia, Sphagnum, –, Pteridophyte Botrychium, Lycopodium, –, Angiosperm Neottia (birds nest orchid)., Saprophyte can also be facultative or obligate., Obligate saprophytes are strict saprophytes or, holosaprophytes., Facultative saprophytes are plants with other types, of nutrition which can live as saprophytes., Parasite is an organism which lives in constant, association with some other organism (called host), and obtain its food without killing the host., Parasites can be total (or holoparasite) or partial, (or semiparasite) parasites., The parasites which are nongreen and obtain, their total food (including organic nutrients, water, and minerals) from the hosts are called, holoparasites. E.g. Cuscuta, Cassytha, Orobanche,, Balanophora, Rafflesia, Cistanche, etc., The parasites which are green and can synthesize, their own food but depend on host for water
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ĽňĚŕďń– ░śŚŕĽŚĽŐň– Ľň– ▓ńďňŚř, , l, , l, l, , l, l, , l, l, l, l, l, , l, , l, , l, l, , l, , and mineral supply are called partial or, semiparasites. E.g. Loranthus, Viscus,, Arceutobium, Striga, Santalum album, Thesium etc., Important angiospermic parasites are –, –, Total stem parasite Cuscuta (Amarbel), –, Partial stem parasite Viscum (Mistletoe), and Loranthus, –, Total root parasite Orobanche (Broom rape), –, Partial root parasite Santalum on roots of, Dalbergia, Striga on roots of sugar cane and, Thesium on the roots of grasses., Parasitic plants obtain nutrition from host plants, by penetrating with their haustoria., Haustoria are small modified adventitious roots, which deeply penetrate into the body of host. The, vascular tissue of parasite makes contact with that, of the host through these haustoria., Orobanche have no chlorophylls., Rafflesia is a total root parasite. It is the largest, flower in the world. It was discovered by Sir, Stamford Raffles., Santalum album is an evergreen partial root, parasite and grows at many places in South India., Parasite can be obligate or facultative., Obligate parasite remain parasitic throughout their, life. They cannot live independent of the host., Epiphytes lives on the plants only for the sake of, shelter., Viscum, having permanent attachment to the host,, considered as partial parasite because of the, presence of green leaves., Insectivorous plants are predator plants which are, otherwise autotrophic but they grow in marshy or, muddy soils, which are generally deficient in, nitrogen and in order to fulfil their nitrogen, requirement, these plants catch small insects and, are also called carnivorous plants., They have poorly developed roots and thus, they, have to depend on captured insects for their, nitrogen requirement., The organs and specially leaves of carnivorous, plants are modified variously to catch the insects., These plants have glands which secretes proteolytic, enzymes for breaking complex proteins into simple, nitrogenous substance, which inturn are absorbed, by plants., Insectivorous plants are example of predation i.e., first killing and then eating., , 333, , Table : Some common insectivorous plants, Scientific name, Common name, Pitcher plant, Nepenthes, Sundew plant, Drosera, Utricularia, Bladderwort, Butterwort, Pinguicula, Devil’s boot, Sarracenia, Water flea trap, Aldrovanda, Fly catcher plant, Cephalotus, Dionaea, Venus fly hap, l, l, l, , l, , l, , l, l, l, l, l, , N. khasiana. is the only Indian species grown in, north east., Mature leaf of Drosera possesses large number of, club shaped hairs called tentacles., The digestive glands in Pinguicula are of two, types the stalked glands (or mucilage glands), that secrete mucilage and sessile glands (or, digestive glands) which secrete digestive fluid., Dionaea has a sole species D.muscipula,, distributed in damp, mossy spots in the South, Eastern states of the U.S.A., Aldrovanda (water fly trap), widely distributed, is, small, rootless, aquatic freefloating herb. Each, lobe bears a large number of sensitive hairs and, digestive glands on its upper surface to trap and, digest the insects., When a bladder of Utricularia is full of, unassimilated matter, it degenerates., In Nepenthes the insect proteins are digested by the, enzyme pepsin hydrochloride., About 600 species of insectivorous plants exists., The genus with largest number of species (among, carnivorous plants) is Utricularia., The biggest carnivorous plant is in the genus, Nepenthes., , MINERAL NUTRITION, l, l, l, l, , l, , Absorption of minerals and their utilisation by, plants is called mineral nutrition., Mineral elements present in plants are estimated, by ash analysis., Aristotle thought that plants absorb nutrients in the, organic form from the soil., Water is more important for plant’s growth and, was proved experimentally by J.B. Von Helmont, (l7th century)., Not only water but materials dissolved in it are, essential for plant growth. This was proved by John, Woodward.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 334, , l, , l, , l, , l, , l, l, , l, , l, l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Elements which are required by plants for normal, growth and development and without which plants, cannot complete their life cycle are called essential, elements., Elements which are present in the plant body and, are not so required by plants are called nonessential, elements, eg : Na, Si, Al, Se, Sr, V., Number of essential elements required by plants, is 16. (C, H, O, N, P, K, S, Mg, Ca, Fe, B, Mn, Cu,, Zn, Mo, Cl)., Criteria of essentiality were proposed by Arnon, and Stout and are popularly known as Arnon's, criteria of essentiality., Deficiency of essential element cannot be, compensated by any other element., Element must form a component which is bio, chemically or directly involved in a metabolic, process., Essential elements required by plants in large, quantity are called macronutrients and in minute, quantity are called micronutrients or trace, elements., Nine macro elements are C, H, O, N, P, K, S, Ca,, Mg., Seven micronutrients are Fe, Mn, Mo, B, Zn, Cu,, Cl., Nitrogen, potassium and phosphorus are called, critical elements because these are the minerals, which become deficient in agricultural soil., Fertilizers containing all the three critical elements, (N, P, K) are called complete fertilizers., Essential elements derived from soil are termed as, mineral element, eg P, K, S, Mg, Ca, Fe, Zn, Mn,, B, Cu, Mo, Cl, N., Essential elements obtained from air or water are, called nonmineral element, eg. C, O, H, N., Elements required by plants, Essential, Required by plant from, external means, Macro nutrient, required in large, quantity, , l, , Non Essential, Not required by plants, from external means,, present in plant body, Micro nutrient, required in, less quantity, , Deficiency symptoms, also called hunger signs,, are externally visible pathological conditions, (morphological and physiological deformities or, , abnormalities) which are produced due to absence, or deficiency of some essential nutritive, substance., l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, l, , l, l, , Deficiency symptoms (diseases) of essential, elements are determined by water culture and, sand culture experiments., Cultivation of plants in a balanced nutrient solution, without any soil is called hydroponics. It is also, known as soil less culture/water culture/ solution, culture. Water culture experiments were first, conducted by Sachs., The book on the diagnosis of mineral deficiencies, in plants was written by Wallace., Hydroponic culture solution was first prepared by, Knop., Hydroponics or soilless culture helps in, knowing –, –, The essentiality of mineral elements., –, The deficiency symptoms developed due to, nonavailability of particular nutrient., –, Toxicity to plant when element is present in excess., –, Possible interaction among different elements, present in plants., –, The role of essential elements in the, metabolism of plant., Cultivation of plants in sterilized sand, supplemented with nutrient solution is called sand, culture., Sand culture experiment is advantageous since, it provides physical support and aeration to the, root system., Disadvantages of soil culture are : pH values of, the media cannot be adjusted; quantities of mineral, elements absorbed by plants cannot be estimated., Balanced nutrient solution is prepared by, dissolving different proportions of minerals in, distilled water., The famous nutrient solutions are Knop solution,, Hoagland solution, Arnon's solution and Sach’s, solution., Mottling is patches of green and nongreen areas., White bud is chlorosis affecting young leaves as, well as buds so that the latter are whitish instead, of greenish colour., Nickel is called 17th essential element by Dalton, et al, 1988. It is the component of enzyme urease., Law of minimum was given by Liebig (1840), which states that productivity of a soil depends upon, the proportionate amount of deficient mineral.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ĽňĚŕďń– ░śŚŕĽŚĽŐň– Ľň– ▓ńďňŚř–, l, , The elements which produce protoplasmic, constitutents like proteins, nucleic acids etc. are, called protoplasmic elements., , Macronutrients, l, l, l, l, , l, l, l, , C, H, O are the structural elements or frame, work or building block elements., Element which is absorbed by plants exclusively, from air is carbon (in the form of CO2)., Element which forms a main component of the, dry weight of the plant body is (45%) carbon., An element which is useful in reduction, reactions and in the formation of metabolic, water is hydrogen., The element which is absorbed from air and, water both is oxygen., Element which forms main component of fresh, weight is oxygen., Deficiency symptoms are not formed for C, H,, O because plants cannot survive without C, H, O., , Nitrogen, l, Nitrogen is the constituent of organic compounds, such as chlorophyll, aminoacids, purines,, pyrimidines, enzymes, and many coenzymes, e.g., NAD, FAD, NADP & ATP., l, Main form in which nitrogen is absorbed by plants, is nitrates. Plants also absorb nitrogen in the form, of NH4 + (ammonium) ions., l, After carbon, hydrogen and oxygen, nitrogen is, the major constituent of the protoplasm., l, Nitrogen deficiency in the soil occurs because, –, Nitrogen compounds are absent in the parent, rocks., –, Excess utilization of N2 by plants., l, N2 deficiency in the soil can be rectified by, supplying manures, urea, DAP (diammonium, phosphate), green manure and biofertilizers., l, Deficiency of N2 results in chlorosis of older, leaves (yellowing of leaves)., l, For mobile elements deficiency symptoms first, appear in older leaves and later in younger, leaves., l, Chlorosis is the most common deficiency, symptom of minerals., l, Plant parts become purple due to deficiency of, N2 which results in the formation of anthocyanin, pigments., l, Nitrogen is the main constituent of the amino acids, , 335, , and proteins. Hence its deficiency results in many, metabolic disorders like smaller cells with slow division, rate, less yield, decreased protein synthesis etc., Phosphorus, l, Phosphorus is absorbed by the plants as phosphate, ( H 2PO 42 - , PO 34- ) ions., l, It is essential for the synthesis of ATP and NADP+., l, Phosphorus is a component of nucleic acids,, phospholipids, coenzymes NAD, NADP, energy, rich compounds ATP, ADP, GTP and cell, membranes., l, Phosphorus is found abundantly in the growing, and storage organs., l, Chlorosis of old leaves, purple colour, stunted, growth, premature leaf fall and delayed flowering, are the deficiency symptoms of phosphorus., Potassium, l, Potassium is absorbed as K+ ions (cations)., l, K+ ion is not a component of plant body., l, It is abundant in clayed soils but absent in loose, soils (sandy soils) due to leaching., l, Most common free ion in the cell is K+ ., l, Element essential for maintaining the turgidity, of guard cells is K+ . Hence it is involved in, stomatal movements., l, Element essential for maintaining ionic, equilibrium., l, K+ is an activator for many enzymes like pyruvic, kinase, DNA polymerase., l, It helps in the permeability of cell membranes and, translocation of organic solutes in the phloem., l, Deficiency symptoms of potassium are , –, Mottled chlorosis appearing first in older, leaves,, –, Marginal yellowing or scorch and curling,, premature death,, –, Loss of apical dominance, –, Cereals may show lodging, falling of cereal, crops by the time of harvesting., Sulphur, l, Sulphur is absorbed by the plants as sulphate ions., (SO4–). It is also absorbed from air as SO2 ., l, The pungent smell of onion and garlic is due, to sulphur (contained in allyl oils)., l, Sulphur containing amino acids are cysteine,, cystine, methionine., l, Sulphur is an important element because –
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 336, , ŕďőĽę– ĐĽŐńŐĹť, , It plays a role in the synthesis of chlorophyll, It is a constitutent of ferredoxin and some, lipids of chloroplasts, –, It is essential for nodulation in legumes, –, It determines the structure of protein, –, It plays a role as a part of active centre of, some enzymes and affects various metabolic, processes., l, Deficiency symptoms of sulphur are –, –, Chlorosis more commonly appearing first in, young leaves and leaf curl, –, Less juice content in Citrus, –, Reduced nodulation in legumes and, defoliation in tea., Calcium, l, Calcium is absorbed by plants as Ca+ ions., l, It is the component of middle lamella (associated, with pectic substances)., l, It is present in the vacuoles in the form of CaCO3, and calcium oxalate crystals., l, Calcium is also essential because, –, It takes part in the formation of root nodules., –, It is an activator of enzyme amylase, –, It controls cell permeability, –, It is important in the formation of cell, membranes, –, It is essential for continued growth of the, apical meristem. Calcium in small amounts, is necessary for normal mitosis as it is, important in chromatin or mitotic spindle, organization, –, It is responsible to reduce toxicity by forming, calcium salts or organic acids., l, Deficiency of calcium causes –, –, Degeneration of root, stem tips and, gelatinisation of roots, –, Stunted growth, –, Termination of growth in meristematic region, –, Chlorosis of younger leaves which later on, become necrotic, –, Premature flower abscission etc., –, –, , Magnesium, l, It is absorbed by plants as Mg ++ ions., l, Element essential for the synthesis of chlorophyll., l, Magnesium is present in the centre of the, porphyrin ring of chlorophyll., l, Magnesium is useful for attachment of sub units, of ribosomes., , l, l, , lnterveinal chlorosis of older leaves is due to, deficiency of magnesium., Deficiency of magnesium results in, –, Marginal curling,, –, Interveinal chlorosis with anthocyanin, pigmentation appearing first in older leaves,, veins green, –, Reduced growth, underdeveloped phloem., , Micronutrients, Iron, , Available mostly in ferrous form and rarely in, ferric form (Fe 3+)., l, Element essential for synthesis of chlorophyll., l, Iron is present in ferredoxine and cytochromes, responsible for electron transport system in plants., l, Deficiency of iron causes –, –, Marked chlorosis particularly in younger, leaves, the mature leaves remain, uneffected, –, Characteristic interveinal chlorotic spots, develop and the principal veins remain, typically green showing fine network of, reticulate venation, –, Inhibits chloroplast formation, –, Stalks become short and slender., Manganese, l, Absorbed by plants as Mn++ ions., l, Manganese primarily functions as activator of, several enzymes such as, –, Malic dehydrogenase and oxalosuccinic, dehydrogenase – the enzymes of Krebs cycle, –, Nitrate reductase and hydroxylamine reductase, (thus play important role in nitrogen, metabolism)., l, Manganese plays a role in the photooxidation, of H 2 O and release of molecular O 2 during, photosynthesis. It is also involved in the synthesis, of chlorophyll and oxidation of auxin (indole, 3acetic acid)., l, Deficiency of manganese results in interveinal, chlorosis, grey spots or stripes, legume cotyledons, with brownish spots (marsh spot disease) and, sterile flowers., Molybdenum, l, Absorbed as molybdate ions (Mo3+ or Mo4+), l, It is useful for nitrogen metabolism. It is also a, component of nitrate reductase., l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 337, , ▐ĽňĚŕďń– ░śŚŕĽŚĽŐň– Ľň– ▓ńďňŚř–, , Deficiency of molybdenum causes –, –, Chlorotic interveinal mottling of mature leaves, followed by necrosis and folding of leaves., –, Inhibition of flowering, –, Whiptail disease (transformation of, cauliflower leaf into a cylinderical structure, called whiptail) of cauliflower., Boron, l, Plants absorb boron as borate and tetraborate, ions (BO 33 - or B 4O 72 - ) ., l, It helps in absorption of water and calcium and, in pectin synthesis., l, It is also required for pollen germination, cell, differentiation and carbohydrate translocation., l, Sugar is translocated in the form of sugarborate, complex., l, Deficiency symptoms of boron are, –, Death of shoot tips because boron is needed, for DNA synthesis, –, Leaves develop a thick coppery texture, they, curve and become brittle, –, Root growth is arrested and flowers are not, formed, –, Causes diseases like ‘heart rot’ of apple,, ‘internal cork’ of apple, ‘water cork’ in, turnip, ‘stem crack’ of celery., Zinc, l, Absorbed as Zn++ ions., l, It acts as enzyme activator particularly for, carbonic dehydrogenase, alcohol dehydrogenase, etc., l, Required for synthesis of IAA (auxin) or its, precursor tryptophan, l, Deficiency symptoms of zinc are –, –, Interveinal chlorosis in mature leaves, beginning from margin and apex followed by, necrosis, –, Little leaf disease in several plants, –, ‘Rosette’ due to shortening of internodes, –, ‘White bud’ of maize, –, ‘Mottled leaf’ in apple and walnut., Copper, l, Absorbed as cuprous or cupric forms (Cu2+ or Cu+)., l, Copper is a structural component of, plastocyanin and plastoquinone., l, Element required for the synthesis of vitaminC, (ascorbic acid) and activator of polyphenol, oxidase., l, , Deficiency symptoms of copper are –, –, Necrosis at leaf tip and margins, –, ‘Die back’ in Citrus, –, ‘Exanthemma’ in fruit trees; this disease is, characterised by die back, appearance of, brown spots on leaves and fruits., –, ‘Reclamation’ in cereals and legumes; this, disease is characterised by chlorosis on leaf, tips and there is no seed setting., –, Wilting of entire plant occurs under acute, shortage of copper., Chlorine, l, Chlorine is a component of oxygen liberation, complex of photolysis., l, Chlorine is a constituent of amylase, plays vital, role in anion cation balance., l, The main function of chlorine is ph oto, reduction of oxygen, cell division, normal fruit, production., l, Deficiency symptoms of chlorine show –, –, Leaf wilting, bronze colour, –, Chlorosis and necrosis, –, Stunting of roots and swollen root tips, –, Flower abscission and reduced fruiting., l, , Mineral indicators, Name of plant, Agrocyst, Astragalus and Stanley, Impatiens balsamina, Ocimum homblei, Gypsophila, Asplenium adulterium, , or bio indicator plants, Mineral indicated, –, Leadmine, –, Selenium, –, Zinc, –, Copper, –, Gypsum, –, Nickel, , Non-essential elements, l, l, l., l, l, l, l, , Sodium is used by blue green algae, marine algae, and C4 plants., In higher plants, sodium maintains differential, permeability of cytomembrane., Silicon is present in grasses, sedges, Equisetum etc., Cobalt, the component of vitamin B12, is found, in few blue green algae and Rhizobium., Some marine algae like Laminaria accumulate, iodine in huge amounts., Aspergillus niger and Lemna minor need gallium, for their growth., Gold is known to occur in pteridophyte,, Equisetum.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 338, , Element, 1. Nitrogen, , ŕďőĽę– ĐĽŐńŐĹť, , Obtained as, , Table : Role of elements in plants, Role, Macronutrients, , Deficiency symptoms, , NO3–, NH4– rarely Cell division, growth, Chlorosis starting from older leaves, stunted, NH2, metabolic, activities, growth due to decreased protein synthesis,, photosynthesis, smaller cells and inhibition or slow divisions,, permature leaf fall, lateral buds and tillering, suppressed, late flowering, purple colouration, on surface of shoot axis, wrinkling of cereal, grains, reduced yield., , 2. Phosphorus H2PO42–, PO43–, , Energy transfer, cell division, Stunted growth, leaves dull green or with purple, membranes phosphorylation and red spots of anthocyanins, chlorosis with, reactions, necrosis first in older leaves or premature, abscission, delayed flowering, premature fall of, flower buds, poor vascular tissues and delayed, seed germination., , 3. Potassium, , K+, , Maintenance of cell turgidity,, opening and closing of stomata,, balancing other ions, cation, anion balance, increases, hardiness, essential for, photosynthesis, respiration,, protein synthesis and synthesis, of various other types, membrane permeability, , 4. Magnesium, , Mg2+, , Central atom of chlorophyll, Interveinal chlorosis of older leaves, appearance, stabilizes ribosomes, activator of brightly coloured pigments, necrosis of older, for many enzymes of leaves in acute shortage., photosynthesis and respiration., , 5. Calcium, , Ca2+, , Constituent of middle Formation of multinucleate cells, chlorosis, lamellae,, involved, in along margins of younger leaves, formation of, formation of nucleus and stunted and discoloured roots., mitochondria, activator of, enzymes like amylase., , 6. Sulphur, , SO42–, , 7. Iron, , Fe2+ or Fe3+, , Constituent of amino acids Chlorosis of younger leaves, methionine and cysteine., Constituent of vitamins like, thia mine,, biotin, and, coenzyme A., Micronutrients, Constituent of electron carriers Interveinal chlorosis of younger leaves, necrosis, like, ferredoxin, and may follow., cytochromes, essential for, synthesis of chlorophyll,, activator for oxidising, enzymes., contd ..., , Mottled interveinal chlorosis appearing first in, older leaves, marginal or apical yellowing or, scorch and curling, die back, bushy habit,, shorter internodes, loss of apical dominance,, cereals may show lodging, loss of cambial, activity, plastid disintegration and increase in, rate of respiration.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ĽňĚŕďń– ░śŚŕĽŚĽŐň– Ľň– ▓ńďňŚř, , 339, , 8., , Manganese, , Mn2+, , Activator for enzymes of, photosynthesis, and, respiration,, catalyses, splitting of water during, photosynthesis., , Interveinal chlorosis of younger or older, leaves, followed by necrosis, disorganisation, of thylakoids in chloroplasts., , 9., , Zinc, , Zn2+, , Involved in synthesis of, auxins, activator for more, than 80 enzymes., , Interveinal chlorosis of older leaves, followed, by necrosis, little leaf and rosette in some, plants., , 10. Copper, , Cu+ or Cu2+, , Constituent of plastocyanin,, activator for oxidising, enzymes., , Young leaves become twisted and dark green, in colour, exanthema in fruit trees, reclamation, in cereals., , 11. Molybdenum, , MoO42–, , Constituent of nitrate, reductase, essential for, nitrogen fixation and, phosphorus metabolism., , Whip tail in crucifers, interveinal chlorosis of, older leaves followed by necrosis, young, leaves become twisted., , 12. Boron, , H3BO3, , Involved in translocation of, sugars, essential for DNA, synthesis, acts as natural, inhibitor,, promotes, elongation of pollen tube., , Apical region of stem dies, leaves become, thick and dark coloured, flowering suppressed,, heart root of beet, water core of turnip, top, sickness of tobacco etc., , 13. Chlorine, , Cl–, , Stimulates splitting of water, during photosynthesis,, essential for growth of roots, and for division of leaf cells., , Leaves become wilted, leaves may show, chlorosis and necrosis, roots become thick and, stunted., , Absorption of mineral nutrients, l, , l, , It has been shown that uptake of minerals/ions, involves 2 phases., –, In the first phase, ions are rapidly taken into, the free space or outer space of the cells (inter, cellular spaces and cell wall)., –, In the second phase, ions are taken in slowly, into the inner space of the cells (cytoplasm, and vacuoles)., Entry into the outer space does not require energy, but entry into inner space required energy (active, process)., , Passive absorption, l, Passive absorption refers to absorption of minerals, by physical process which do not require meta, bolic energy., l, Any substance moves passively from a region of, its higher concentration to a region of lower con, centration., l, When electrolytes are absorbed, they move pas, sively from a region of higher electrochemical, , l, , l, , l, , l, , potential to a region of lower electrochemical, potential usually through ion channels., Three theories have been discussed to explain, the passive absorption of ions – diffusion, ion, exchange and Donnan equilibrium., Diffusion (mass flow) – According to this hypoth, esis, as the flow of water into the plant increases, due to transpiration pull, the uptake of ions into the, plant also increases. This occurs due to passive, absorption of ions by free diffusion into the appar, ent free space of a tissue., Ion exchange – Both anions and cations have a, tendency to get adsorbed on the surface of cell, wall. These adsorbed ions exchange with the ions, present in the soil solution. Ionic exchange occurs, through carbonic acid exchange and contact, exchange., Donnan equilibrium – Donnan equilibrium is said, to be reached when the product of anions and, cations in the internal solution becomes equal to, the product of anions and cations in the external, solution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 340, , ŕďőĽę– ĐĽŐńŐĹť, , Active absorption, l, The movement of ions against concentration or, electrochemical potential gradients requires energy., l, This energy is derived from metabolism., l, Active uptake of ions is carried out by carrier, mechanism for both influx and efflux., l, The activated ions combine with carrier proteins to, form an ioncarrier complex, utilising metabolic, energy., l, This complex moves across the membrane and, reaches the inner surface., l, The complex breaks and releases ions into the, cytoplasm., , NITROGEN METABOLISM, l, l, l, l, , l, , l, , l, , l, , l, , l, , Nitrogen occurs in environment as oxides, organic, amines etc., Nitrogen content in the environment is 78% by, volume., Plant cannot absorb nitrogen in molecular form., Nitrogen is absorbed by plants in nitrate (NO3- ), and ammonium (NH +4 ) form., Cyclic movement of nitrogen in nature is called, nitrogen cycle. It is useful for maintaining, balance in equilibrium of nitrogen in nature., Nitrogen cycle consists of four processes called, nitrogen fixation, ammonification, nitrification, and denitrification., Nitrogen fixation is the conversion of gaseous, nitrogen into inorganic nitrogenous compounds., Nitrogen fixation is of two types : physical (or, abiological) and biological., Physical nitrogen fixation occurs in atmosphere, in four steps –, –, Conversion of nitrogen into nitric oxide due, Lightening, to lightening. N2 + O2 ¾¾¾¾¾, ® 2NO., –, Oxidation of nitric oxide into nitrogen dioxide., 2NO + O2 ® 2NO2, –, Nitrogen dioxide reaches the soil in the form, of nitrous and nitric acid when dissolved in, rain water., 2NO2 + H2O ® HNO2 + HNO3, –, These react with alkali of soil and form nitrates, (absorbable form)., HNO3 + Ca or K salts ® Ca or K nitrates., On industrial ground abiological fixation occurs, by HaberBosch process at high pressure and, temperature., , l, , l, , l, l, , l, l, , l, l, l, l, l, , l, l, l, l, , l, l, , l, l, , 450°C, N2 + 3H2 ¾¾¾¾, ® 2NH3, 200 atm, Conversion of gaseous nitrogen into nitrogenous, compound by living organism is called biological, nitrogen fixation., Hellriegel and Wilforth demonstrated the ability, of leguminous plant to assimilate molecular, nitrogen due to presence of microbes in root, nodules., Biological nitrogen fixation is of two types, symbiotic and nonsymbiotic., Symbiotic nitrogen fixation is the fixation of, nitrogen as ammonia by microorganisms living in, symbiotic association with higher plants., Rhizobium in root nodules of legume plant is the, best example showing symbiotic nitrogen fixation., Nonlegume plants like Casuarina, Myrica also, show nodulation on their roots which contain, nitrogen fixing actinomycetes., Symbiotic nitrogen fixation requires nod genes of, legumes, nod fix and nif genes clusters of bacteria., Nitrogen fixation by free living organisms is called, nonsymbiotic fixation of nitrogen., Examples of aerobic nonsymbiotic bacteria are, Azotobacter and Beijerinckia., Clostridium represents example of anaerobic non, symbiotic bacteria., Chlorobium, Rhodospirillum are photosynthetic, and Desulphovibrio are chemosynthetic, nonsymbiotic bacteria., Some blue green algae also fix nitrogen non, symbiotically, for eg. Nostoc, Anabaena, Aulosira etc., The mechanism of biological nitrogen fixation was, studied by using 15N (radioactive nitrogen)., Main enzyme necessary for biological nitrogen, fixation is nitrogenase., Eight protons and six electrons are required to, reduce a molecule of nitrogen into two molecules, of ammonium., Synthesis of nitrogenase enzyme is established by, nif gene., Nitrogenase is made of two subunits. The larger, component beside C, H, O, N & S contains, molybdenum and iron. Whereas the smaller, subunit has no molybdenum., Scheme for mechanism of nonsymbiotic nitrogen, fixation was proposed by Burris., Hydrogen is used in the conversion of molecular, nitrogen to ammonia.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ĽňĚŕďń– ░śŚŕĽŚĽŐň– Ľň– ▓ńďňŚř–, l, , The enzyme nitrogenase successively reduces N2, into dimide and hydrazine and finally to, with the utilisation of ATP., , 2NH+4, , N º N ® NH = NH ® NH 2 - NH 2 ® 2NH +4, , Nitrogen, l, l, , l, , l, , l, , l, l, , l, , l, l, l, l, , l, , l, , l, , l, l, , l, , D imide, , Hydrazine, , Ammonium, , Hydrogen ions and electrons for reduction process, is provided by reduced ferridoxin., Nitrogenase acts only in anaerobic condition,, under aerobic condition it undergoes irreversible, damage., The enzyme nitrogenase requires ATP, Mg++, an, electron source and anaerobic conditions for, converting nitrogen to ammonia., Anaerobic condition in symbiotic nitrogen fixation, is provided by leghaemoglobin present in root, nodules., Leghaemoglobin is a red colour haemoglobin like, pigment which absorb oxygen and protect enzyme, from oxygen., This pigment is called oxygen scavenger or, biochemical curtain., Ammonification (second process) is the conversion, of organic nitrogenous compounds from the dead, bodies of plants and animals into ammonia., Those bacteria which bring about the process of, ammonification is called ammonifying bacteria,, bacteria of decay or putrefying bacteria., Examples of ammonifying bacteria are – Bacillus, ramosus, Bacillus vulgaris., Ammonification is a mineralisation process., Proteins of dead bodies of plants and animals is, degraded by bacteria and saprophytic fungi., The anaerobic decomposition of proteins (amino, acid to amine and related compounds) is called, putrefaction., Oxidative deamination (deamination of amino, acid in presence of oxygen) results in release of, ammonia., If ammonia is not absorbed directly by plants then, it is converted to nitrate through the process of, nitrification., Nitrification (third process) is the conversion of, ammonia into nitrite and nitrates by soil bacteria, (nitrifying bacteria)., Nitrosomonas, Nitrosococcus, Nitrosomonas, convert ammonia into nitrites., Nitrites are converted to nitrates by the action of, Nitrobacter., Heterotrophic nitrification is the nitrification, , l, l, l, , l, l, l, , 341, , brought about by heterotrophic bacteria (Nocardia), and fungi (Aspergillus)., High nitrification in aquatic habitat causes major, biological oxygen demand (BOD)., Assimilatory nitrate reduction is the reduction of, nitrates to ammonia within plant body., Conversion of nitrates and ammonia of soil to, molecular nitrogen by bacteria is called, denitrification (fourth process). This is done by, anaerobic bacteria like Pseudomonas, denitrificans, Thiobacillus denitrificans., Denitrification is also called dissimilatory nitrate, reduction., Denitrification occurs in four steps, NO–3 ® NO–2 ® NO ® N2 - (molecular form)., Nitrates are reduced to nitrites by the enzyme, nitrate reductase. The nitrites are reduced to ammonia, by nitrite reductase. The ammonia so formed is, enzymatically incorporated in amino acid., , APPLICATION OF FERTILIZER, l, , l, l, l, , l, , l, , l, , The key role of fertilizers and their judicious use, in crop husbandry is well understood. Soil normally, contain sufficient amount of essential minerals., Plant roots take up plant food elements from the, soil in ionic forms., The positively charged ions are called cations, e.g,, K+, Ca++, Mg++, Fe+++, Zn++ and so on., The negatively charged ions are called anions, e.g.,, NO3–, H2PO4–, etc., Due to the repeated cultivation, three important, elements i.e., nitrogen, phosphorus, and, potassium are depleted from fields & they need to, be replenished. They are grouped as nitrogenous, fertilizers, phosphatic fertilizers, potassic, fertilizers respectively., Mixed fertilizers as NPK usually meet nutrients, deficiencies in a more balanced manner and require, less labour to apply than straight fertilizer used, separately. Mixtures containing all the three, principal nutrients (N, P & K) are called complete, fertilizers., NPK fertilizers contain nitrophosphate in varying, proportions like 17 : 18 : 9 or 15 : 15 : 15, (representing percentage by weight of nitrogen,, phosphorus and water soluble potassium)., Thus, the use of fertilizers restores the fertility of, the soil but dosages differ according to crop, soil, season and other climatic conditions.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 342, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 36, , Photosynthesis, l, , l, , l, , Photosynthesis (Gk. photon = light, synthesis =, putting together) is the most important anabolic, process on earth by which green plants (autotrophic, organisms) synthesize complex carbohydrates from, simple substances like carbon dioxide and water, with the help of light energy and purify the, atmospheric air by consuming carbon dioxide and, evolving oxygen., The process of photosynthesis can also be, defined as the transformation of photonic, energy (i.e., light or radiant energy) into, chemical energy (locked in high energy bonds, of carbohydrate molecules) by the green parts, of the plants., The simplest equation for photosynthesis in higher, plants and algae can be –, , l, l, , l, , l, , Light, , 6CO2 + 12 H2O Chlorophyll C6 H12O6 + 6O2-, , + 6H2O., , l, l, l, l, , l, , l, , l, , Photosynthesis is photoautotrophism., Plants which carry out photosynthesis are called, photoautotrophs., The important feature of photosynthesis is, conversion of light energy into chemical energy., The process of manufacture of organic substances, by certain bacteria utilising directly the chemical, energy released in the oxidation of inorganic, substances is called chemosynthesis. [For more, details refer chapter Monera], Bacteria performing chemosynthesis are called, chemoautotrophs (chemosynthetic bacteria). For, eg., nitrifying bacteria., Organisms which manufacture their own food are, called autotrophs and those which depend on, autotrophs for their food requirements are called, heterotrophs., Heterotrophs which depend completely on, , l, l, l, l, l, l, l, l, l, l, , photoautotrophs for their survival are called, herbivores (vegetarians)., Heterotrophs which can survive on dead organic, matter are called saprophytes., Green plants can survive in the absence of, herbivores, carnivores and omnivores but cannot, survive in nature devoid of saprophytes because the, raw materials required by these plants are formed, by the action of saprophytes., All heterotrophic organisms depend directly or, indirectly on photoautotrophs as O2 required for, respiration of aerobic organisms is liberated during, photosynthesis., Initially cyanobacteria were the main source of, oxygen (by photosynthesis) in the atmosphere and, this oxygen of the atmosphere is balanced by, continuous photosynthesis and respiration., Photosynthesis is an anabolic or constructive, process., Dry weight of the plant increases due to, photosynthesis., Photosynthesis is an endergonic (occurring inside, the organ) reaction., Ultimate source of energy for all organisms is, sunlight., Photosynthesis is an oxidation reduction process, where H2O is oxidised and CO2 is reduced., Light is essential for photosynthesis. This fact was, discovered by IngenHousz., CO2 and H2O are essential for photosynthesis, was, proposed by Theodore de Sassure., Absorption of CO2 during photosynthesis was, proposed by Senebier., O2 is liberated during photosynthesis and it was, discovered by Joseph Priestly., Oxygen evolved in the food manufacture process
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ĺŐŚŐřťňŚĺĚřĽř, , l, l, l, , l, , comes from CO2. This was stated by Senebier, (1782)., Dutrochet (1937) confirmed that chlorophyll is, essential for the process of photosynthesis., Liebig (1840) reported that the sole source of, carbon in plant is CO2., The seat of photosynthesis is chloroplast and the, first visible product, starch, was discovered by, Julius Sachs., Photosynthesis mainly occurs in the mesophyll, cells of leaves and to a very little extent in the, green stems and floral parts (sepals). Mesophyll, cells contains chloroplasts arranged along their outer, margin., , l, , l, , l, l, , l, , l, l, l, , l, , l, l, l, , Chloroplasts (Gk = chloros = green, plastos =, moulded) are the green plastids which occur in all, the green parts of the plants., Chloroplasts are often called food production, centres of the cell (Assimilatory centres/, photosynthetic factories)., Chloroplasts are the actual sites of photosynthesis., The chloroplasts contain chlorophyll and, carotenoid pigments which are responsible for, trapping light energy essential for, photosynthesis., Majority of the chloroplasts of the green plants are, formed in the mesophyll cells of the leaves. They, are lens shaped, oval, spherical, discoid or even, ribbon like organelles having variable length (5 , 10 mm) and width (2 4 mm)., The chloroplasts are double membrane bound, organelle., The space limited by the inner membrane of the, chloroplast is called the stroma., A number of organised flattened membranous sacs, called the thylakoids are present in the stroma., Thylakoids are arranged in stacks like the piles, of coins called grana., The stroma of the chloroplasts contains enzymes, required for the synthesis of carbohydrates and, proteins., Role of light as a source of energy was recognised, by Robert Mayer., The photosynthetic apparatus comprises of, photosynthetic pigments and light., The photosynthetically active pigments are, , c hlo r o p hyl l s , c a rot e noid s and phycobilins, (biliproteins)., As many as eight major types of chlorophyll are, known to exist in the plant kingdom viz., chlorophyll, a, b, c, d and e, bacteriochlorophyll a and b, and, chlorobium chlorophyll., , Photosynthetic pigments, l, , l, l, , CHLOROPLASTS, l, , 343, , l, , l, l, l, , l, , l, , l, l, , l, , l, l, l, , l, , Photosynthetic pigments are located in the, membranes of the thylakoids in specific areas called, quantasomes., Term quantasome was coined by Park and, Biggins., The various contents of quantasome are :, (i) chlorophyll a, (ii) chlorophyll b,, (iii) carotenoids (xanthophylls, carotene), The quantasomes are mainly present in grana, lamellae., Chlorophyll is the main pigment, useful in, photosynthesis., Chlorophyll shows porphyrin structure., Chlorophyll consists of 4 pyrrole rings, (tetrapyrrole head) attached to a magnesium atom, at the centre and also phytol (tail) containing, numerous carbon atoms., Chlorophyll b is similar to chlorophyll a except in, having a formyl (CHO) group instead of methyl, group., Usually the ratio of chlorophyll a and b is, 2.5 – 3.5 : 1. It is 5.5 : 1 in heliophytes and, 1.4 : 1 in sciophytes., The pigments which absorb light and transmit it to, the chlorophyll reaction centre are carotenoids., Carotenoids mainly absorb violet, indigo and blue, wavelength of spectrum but maximum, absorption occurs at blue region., The carotenoids are unsaturated polyhydro, carbons being composed of eight isoprene (C5H8), units., Carotenoids are fat soluble hence sometimes called, as lipochromes., Carotenoids are accessory pigments present in, chloroplast., Carotenoids protect the chlorophyll from a lethal, condition namely photooxidation by a light of high, intensity. Hence these pigments are called shield, pigments., Carotenoids are of two types :
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 344, , –, , l, l, l, l, l, l, l, l, , l, l, l, , l, l, l, , l, l, l, l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , Orange to red coloured carotenoids , carotenes., –, Yellow coloured carotenoids xanthophylls, (carotenols)., Carotenes were first isolated from roots of carrot, hence named carotenes., The lycopene is a red pigment found in ripe tomato, and red pepper fruits., The bcarotene on hydrolysis gives vitamin A hence, called as provitamin A., The most common xanthophyll in green plants is, lutein., The xanthophyll formation takes place in dark, under aerobic condition., The ratio of xanthophyll to carotene in nature is, 2 : 1 in young leaves., Phycobilins comprise a bile pigment attached to, protein., Phycobilins are water soluble pigments mostly, present in the members of red algae and blue green, algae., Phycobilins have a linear tetrapyrrole., Phycoerythrin, phycocyanin are the important, phycobilins., The prefix r and c in phycoerythrin and phycocyanin, indicates the source i.e., rhodophyceae and, cyanophyceae respectively., Electromagnetic radiation from the Sun is received, by plants in the form of photons., A particle of light (photon) containing a packet of, energy is called quantum (hv)., The electromagnetic spectrum comprises of cosmic, rays, grays, Xrays, ultra violet rays, visible, spectrum, infra red rays and radio waves., Visible light ranges from 350 nm 750 nm., Visible light shows 7 colours (VIBGYOR)., Plants usually absorb blue or red coloured lights., Energy value of light is inversely proportional to, its wavelength., A ray of light incident upon a leaf behaves in three, different ways as reflected – 12%, transmitted –, 5% and absorbed – 83%., Only 4% of light is absorbed by chlorophyll out of, total absorbed light., Chlorophyll absorb more of blue wavelength than, red (as indicated by absorption spectrum)., A graph showing absorption of light by chlorophylls, (a, b) at different wavelengths is called absorption, spectrum., , l, l, l, l, l, l, l, , l, , l, , l, l, l, , l, l, , l, l, , Chlorophyll a shows peaks of absorption at 430, and 662 nm of wavelengths of light., Chlorophyll b shows peaks of absorption at 453, and 642 nm wavelengths of light., A graph showing rate of photosynthesis at different, wavelengths is called action spectrum., When radiant energy reflects completely from the, surface of a substance that substance appears white., Substances appear dark when they absorb radiant, energy completely and do not reflect it., Partly reflected light appears coloured., Chlorophyll absorbs all the light except green, portion. Hence chloroplasts with their chlorophylls, impart green colour to the plant parts. Therefore, leaves appear green., The physical change in chlorophyll due to absorption, of radiant energy is responsible for the change in, chemical substances present in the stroma., Chlorophyll shows fluorescence, the property of, almost immediate emission of long wave radiations, by substances after attaining excited state on receipt, of light energy., Isolated chlorophyll in pure form emits red colour, and i.e shows red flourescence., In green plants the electrons are accepted by electron, carriers and later transferred to the chlorophyll., The liberated free energy is utilised in the, synthesis of chemical energy i.e., ATP,, NADPH + H+., Normal energy level of electrons of chlorophyll is, called singlet or ground state., Type of protein present in the stroma is fraction 1, protein. This protein contains an enzyme, RuBP carboxylase., Dark phase reactions of photosynthesis take place, in the stroma., Light phase reactions of photosynthesis occur, in grana regions., , Pigment systems, l, , Light reaction of photosynthesis involves the, participation of two separate pigment synthesis i.e.,, PS I and PS II., , Photosystem I (PS I), l, PS I is located on the outer surface of non , appressed parts of grana thylakoids and fret, channels., l, PS I comprises of about 200 to 400 chlorophylls,, 50 carotenoids, one molecule of P700.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 345, , ▓ĺŐŚŐřťňŚĺĚřĽř–, l, l, , l, l, , It is light green in colour., This system is not directly involved with the photo, oxidation of water and evolution of molecular, oxygen. This system produces a strong reductant, which reduces NADP+ to NADPH., PS I is involved both in cyclic and noncyclic, electron transport., Pigment molecules of PS I absorb at or below, 700 nm wavelength of light., , Photosystem II (PS II), l, PS II is located on the inner surface of appressed, parts of grana thylakoids., l, PS II comprises of about 200 chlorophylls, 50, carotenoids and one molecule P680., l, It is dark green in colour., l, This system is directly involved with the photo–, oxidation of water and evolution of molecular, oxygen., l, PS II donates electrons to PS I when NADP+ is, reduced., l, PS II is involved only in noncyclic electron, transport., l, Pigment molecules of PS II absorb at or below, 680 nm wavelength of light., l, The temperature coefficient (Q10) is defined as, the ratio of the velocity of a reaction at a particular, temperature to that at a temperature 10°C lower., l, For a physical process the value of Q10 is slightly, greater than one., l, For photochemical reaction the value of Q10 is, one., l, For chemical reaction the value of Q10 is two or, more i.e., with the rise of 10°C temperature, the, rate of chemical reaction is doubled., , l, l, , l, l, l, , l, l, l, , l, l, , light, , CO162 + 2H 2O 18 chlorophyll, , l, , The mechanism studied for photosynthesis, demonstrated the existence of two phases : light, phase (photochemical phase) and dark phase, (biosynthetic phase)., , Light reaction, l, l, , l, , The reaction of light phase requires light and hence, called photochemical reaction., Transfer of energy, Emerson effect, photosystem I,, photosystem II, cyclic and, noncyclic, photophosphorylation are the various event and, components of light phase., In the light reaction two important products,, , CH2O 16 + H 2O + O 182, , Evolution of oxygen takes place from water and, not from CO2 , during photosynthesis. So the, traditional equation of photosynthesis is changed, as follows –, 6CO2 + 6H 2O, , light, chlorophyll, , C6H12O 6 + 6O 2, , Traditional equation, , MECHANISM OF PHOTOSYNTHESIS, l, , NADPH2 and ATP are formed., Light reaction occurs in the grana of chloroplast., It was observed by Arnon., He also explained that isolated chloroplasts are, capable of fixing CO2 resulting in the formation of, carbohydrates., According to Hill and Bendall, light reaction is a, two step electron transport system., In the 1 st step photolysis of water and, photophosphorylation takes place., Splitting up of water and liberation of O2 by, chlorophyll in presence of light and hydrogen, acceptor is called photolysis of water., Hill reaction or photolysis of water was proposed, by Robert Hill., Electron acceptors or hydrogen acceptors oxidise, water and hence called Hill oxidants., Hill oxidants are ferredoxin, quinone,, 2, 6 dichloro endophenol and ferric salts (ferric, oxalate)., NADP+ is natural hydrogen acceptor in plant, cells., Experimental proof for the liberation of O2 from, H2O by using radioactive oxygen (O18) was provided, by Ruben and Kamen (1941)., , 6CO2 + 12H 2O, , C6H12O 6 + 6H 2O + 6O2, Modern equation, , l, l, , l, , l, , ATP, NADPH + H+ are produced in light reaction, and are used for the reduction of CO2., Isolated chloroplast cannot carry out CO2 reduction, because enzymes necessary for CO2 reduction are, leached out during the isolation of chloroplasts., Isolated chloroplasts can carryout CO2 reduction, provided the leached substances are externally, supplied to them., This was proved by D.I Arnon and his associates., Inorganic phosphate is converted into pyrophosphate, (~P) during the transfer of electron from Cyt. b6 to
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 346, , l, , l, l, , l, l, l, l, l, l, l, l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , Cyt f due to potential gradient. i.e., ADP reacts with, Pi and forms ATP. This is called, photophosphorylation., Synthesis of ATP from ADP and Pi is called, phosphorylation. Synthesis of ATP in the, chloroplast in the presence of light is called, photophosphorylation., Photophosphorylation was discovered by Arnon., A r n on id en tified 2 ty pe s o f photophos, phorylation : cyclic photophosphorylation and, noncyclic photophosphorylation., Cyclic phosphorylation involves participation of, only PS I., This system is not concerned with photo, oxidation of water., The electrons excited from PS I return back to, PS I so that the electron transport is cyclic., It is only concerned with production of ATP., It occurs under special conditions when NADPH, starts accumulating., Noncyclic phosphorylation involves the, participitation of both PS I and PS II., The first step is photooxidation of water resulting, in splitting of water into H+, e– and release of O2., It involves sequence of electron transfer where, NADP+ is reduced by PS I, PS I is reduced by, PS II and PS II is reduced by water so that the, electron transport is noncyclic., It is concerned with reduction of NADP+ and, production of ATP. It occurs under normal, conditions., In the second step reduction of NADP+ takes place., NADP+ reacts with electrons and hydrogen ions, of water to gives rise NADPH+ + H+., Emerson and his associates conducted experiments, in regard to photosynthetic yield (evolution of O2), on an alga namely Chlorella., A sudden decrease in photosynthetic yield (evolution, of O2) in far red light above 680 nm is called red, drop. Red drop was discovered by Emerson and, his associates., Increase in rate of photosynthesis (photosynthetic, yields) due to far red light and red light of shorter, wavelength supplied simultaneously is called, Emerson enhancement effect., Quantum yield is the number of oxygen molecules, produced per quantum of light. Its value is 0.125., , l, , 8 quanta of light are required for 1 molecule, of O2., , Dark reaction, l, l, l, l, l, l, , l, , Dark reaction occurs even in the presence of light, but it doesn't require light., Dark reaction depends on the light reaction for, assimilatory powers., Dark reaction is a thermochemical reaction., Dark reaction takes place in the stroma of the, chloroplast., Dark reaction is also called CO2 fixation or carbon, assimilation., The mechanism of dark reaction consists of, 3 phases – carboxylation, reduction, and, regeneration of CO2 acceptor., Depending upon the number of carbon atoms in the, first stable product of dark reaction, first, photoautotrophic plants are classified into 2 types –, C3 plants and C4 plants., , Calvin cycle or C3 pathway, l, Carbon assimilation in C3 plants was explained by, Melvin Calvin et al (Benson, Bassham) in Chlorella, and Scenedesmus by using radioactive isotope 14CO2., l, Techniques used by Melvin Calvin et al a r e, chromatography and autoradiography., l, In honour of Melvin Calvin the sequence of reactions, of carbon assimilation in C3 plants is called Calvin, cycle., l, Calvin was awarded with Nobel prize in 1961., l, Calvin cycle is also called Calvin – Benson cycle, C3, – Pathwayor reductive pentose phosphate pathway., l, Plants showing C3 pathway are called C3 plants., l, Calvin cycle has to take place 6 times for the, formation of a molecule of glucose because only, precursor of carbohydrate (CH2O) is formed when, 1 molecule of CO 2 participates in the, carboxylation., l, RuBP (Ribulose bi phosphate), a 5 C compound is, the CO2 acceptor in C3 plants., l, Enzyme useful for this carboxylation is RuBP, carboxylase (RuBPase) (carboxydismutase – old, name), also called RUBISCO., l, 6 molecules of CO2 react with 6 molecules of RuBP, to form an unstable hexose compound., l, 6 molecules of unstable compound immediately, converted into 12 molecules of PGA, (phosphoglyceric acid)., l, In this process 6H2O are utilised.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 348, , l, , l, l, , l, l, l, l, , l, l, , l, , l, l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Out of 12 molecules of GAP, 5 molecules are, isomerised to 5 molecules of DHAP (Dihydroxy, acetone phosphate)., Enzyme utilised is triosephosphate isomerase (GAP, Ketol isomerase)., 3PGAL exists in dynamic equilibrium with, DHAP and both are together known as, triosephosphate., Third phase of Calvin cycle is the regeneration, phase., During this phase 1/6 th of total PGAL is utilised to form, a hexose molecule as a net gain., 5/6th of the total PGAL is utilised to regenerate 6, molecule of RuBP by utilising 6 ATP., During regeneration phase first step is condensation, of six triose molecule to form 3 molecule of fructose, 1–6–diphosphate., The enzyme utilised is aldolase., In second step three fructose diphosphate molecules, are dephosphorylated to 3 molecules of fructose, 6phosphate by the action of fructose phosphatase., Out of three fructose 6phosphate, 1 fructose, phosphate by reversal glycolytic reaction is, converted into glucose., Glucose is converted into either sucrose or starch., The, remaining, two, molecules, of, fructose6phosphate (2/3) react with two molecules, of PGAL to form 2 molecules of xylulose 5, phosphate and 2 molecules of erythrose, 4phosphate. This reaction is catalysed by, transketolase., Two molecules of erythrose 4phosphate react with, 2 molecules of DHAP to form 2 molecules of, sedoheptulose diphosphate. This reaction occurs, in the presence of transaldolase., Two molecules of sedoheptulose monophosphate, are formed from sedoheptulose diphosphate by the, action of phosphatase, this is dephosphorylation., Two molecules of sedoheptulose monophosphate, and 2 molecules of PGAL react to form 2 molecules, of xylulose 5phosphate and 2 molecules of ribose, 5phosphate. This reaction is catalysed by, transketolase., Four molecules of xylulose 5phosphate (formed, earlier) isomerise into four molecules of ribulose, 5phosphate. The enzyme utilised is, phosphoketopentoisomerase., Two molecules of ribose 5phosphate (formed, , l, , l, l, , l, , earlier) isomerise into 2 molecules of ribulose, 5phosphate by the action of phosphoribose, isomerase. Thus 6 molecules of ribulose, monophosphate (Ru5phosphate) are formed., These six molecules of ribulose 5phosphate are, converted to six molecules of ribulose biphosphate, by phosphopentokinase., 6 ATP are utilised in phosphorylation reaction., Overall reaction of Calvin cycle is –, RuBP + 6 CO2 + 18 ATP + 12 NADPH + H+ ®, 6 RuBP + Glucose + 6 H 2 O + 18 ADP, + 12 NADP+., One molecule of glucose is formed from 6 CO 2, by utilising 18 ATP and 12 NADPH + H +., , Hatch & Slack pathway or C4 cycle, C4 acid (dicarboxylic acid) is formed due to, carboxylation was shown by Kortschak et al in, sugarcane., l, In 1960, Hatch and Slack established the above, idea by conducting experiments on leaves of, maize and grasses., l, C4 pathway is called Hatch & Slack cycle. It is also, known as cooperative photosynthesis., l, HatchSlack cycle occurs in chloroplasts of, mesophyll cells and bundle sheath cells., l, Primary acceptor of CO 2 in C 4 plants is, phosphoenol pyruvic acid (PEP)., l, Carboxylation is catalysed by PEP carboxylase, (PEP case)., l, Carboxylation taking place with the help of PEP, case is called bcarboxylation., l, First stable product in C 4 plants is OAA, (oxaloacetic acid)., l, OAA is reduced to malic acid. Enzyme useful for, the reduction is NADP specific malic, dehydrogenase., l, OAA, malic acid and aspartic acid are the, dicarboxylic acids. Hence C4 pathway is also called, C4 dicarboxylic acid cycle., l, Malic acid comes out of the mesophyll cells and, enters the bundle sheath cells through, plasmodesmata., l, Normally malic acid undergoes oxidative, decarboxylation., l, Carbon of C4 acid reaches RuBP and undergoes, carboxylation by carboxydismutase to form PGA., l, The residue of C4 acid (containing 3 carbon atoms), is converted into pyruvic acid., l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ĺŐŚŐřťňŚĺĚřĽř–, l, , l, l, l, l, l, , l, , l, , l, l, , l, , l, l, , As liberated CO2 is accepted by RuBP so, in C4, plants Calvin cycle occurs in the chloroplasts of, bundle sheath cells., Pyruvic acid enters the mesophyll cells and then it, is phosphorylated to PEP by pyruvate dikinase., C4 plants show Kranz type of anatomy i.e., two, types of chloroplasts., Chloroplasts of mesophyll cells are grana rich, and they do not produce starch., Chloroplasts of bundle sheath cells lack grana, but they are starch rich., The leaves of C4 plants requires at least 5ATP and, 2 NADPH to fix one molecules of CO2. Thus, the, pathway requires total 30 ATP and 12 NADPH, molecules to synthesize one molecule of glucose., The C4 plants can absorb CO2 even from a much, low CO2 concentration when the C3 plants fail to, avail it., Thus, the C4 plants can perform a high rate of, photosynthesis even when the stomata are nearly, closed., The C4 cycle requires more light energy to fix CO2, as compared to C3 plants., They also maintain a high rate of photosynthesis, under conditions of water shortage where the C3, plants would stop photosynthesis., Thus, the C4 plants are better adapted to tropical, and desert areas where sun light is more intense, and the growing season is longer., The rate or photosynthesis remains higher due, to absence of photorespiration., They are about twice as efficient as C3 plants in, converting solar energy into production of dry, matter., , Crassulacean acid metabolism (CAM), l, In the members of Crassulaceae, Cactaceae,, Agavaceae, Orchidaceae, Portulacaceae, CO 2, fixation occurs during night only., l, In succulents belonging to the above families the, stomata remain closed during day time in order, to reduce transpiration and open during night, (scotoactive opening)., l, All such plants are called crassulacean acid, metabolisms plants (CAM plants)., l, In CAM plants also OAA is formed due to, carboxylation as in C4 plants., l, Like C4 plants, OAA is reduced to malic acid in, , l, l, l, l, l, l, l, , 349, , CAM plants also. Malic acid is accumulated in, the vacuole., Absorption of CO2 during night and its storage as, organic acid (malic acid) is called acidification., During day time malic acid undergoes oxidative, decarboxylation and CO2 is released., Liberation of CO2 from an organic acid during day, time is called deacidification., The diurnal acidification and deacidification during, the night and day time respectively is called CAM., All reactions of CAM occur in mesophyll cells., Chloroplasts are absent in bundle sheath cells of, CAM plants., CAM pathway is important for the survival of, succulents., , PHOTOSYNTHETIC FACTORS, l, l, , l, , l, l, , l, , l, , l, , l, l, l, l, , Law of minimum was proposed by, Liebeg (1843)., Law of limiting factors (to explain the influence of, external factors on photosynthesis) was proposed, by F.F.Blackman (1905)., When a process is conditioned as to its rapidity by, a number of separate factors the process is limited, by the pace of the slowest factor. This is called the, law of limiting factor., The factor which is at the minimum level is called, limiting factor., When the concentration of the limiting factor is, increased to a certain extent the rate of process also, increases., Factors which influence the rate of photosynthesis, are of two kinds external factors (environmental, factors) and internal factors., The important environmental factors are –, (i) light, (ii) CO 2 conc., (iii) O 2 conc., (iv), temperature, (v) H2O, (vi) mineral salts., Light intensity at which rate of photosynthesis is, equal to the rate of respiration is called, compensation point., If light intensity is increased above compensation, point rate of photosynthesis increases., The degradation of chlorophyll molecule due to high, light intensity is called photooxidation., Photooxidation of chlorophyll under very high light, intensity is called solarization., Rate of photosynthesis is maximum in red light, and then in blue light.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 350, , l, l, l, l, l, l, l, , l, , l, l, , l, l, l, l, , l, , l, , l, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Rate of photosynthesis is minimum in green light., Photosynthesis also occurs in artificial light when, it is provided in sufficient quantities., Plants which can grow in shade are called, sciophytes., Sciophytes have very sensitive and efficient, photosystems to receive diffused light., Plants which can grow in direct sunlight area are, called heliophytes., Rate of photosynthesis is more in intermittent light, (light in flashes) than in continuous light., If CO 2 concentration is increased from, 0.03% to 1% the rate of photosynthesis, also increases., When CO2 conc. is more than 1% the rate of, photosynthesis decreases due to closure of, stomata., CO2 reacts with water to form carbonic acid when, it is in high concentration., The most common limiting factor for, photosynthesis is CO2. Light occupies the next, place., O2 is the byproduct of photosynthesis., Rate of photosynthesis decreases in high, concentration of O2., The inhibitory effect of O2 on photosynthetic rate, is called Warburg effect., In C3 plants high O2 conc. leads to the occurrence, of photorespiration; as a result net yield of, photosynthesis decreases., Temperature has maximum influence on dark phase, of photosynthesis. Hence dark phase is called a, thermochemical reaction., Minimum, optimum and maximum ranges of, temperature (cardinal points) depend on type of a, plant and its geographical distribution., For tropical plants minimum temperature is 0°C. In, maximum temperature photosynthesis decreases due, to denaturation of enzymes., Algae of hot springs can carry out photosynthesis, at 700C., With an increase in temp from 00C to 350C rate of, photosynthesis increases twice for rise of 100C., Therefore Q10 = 2., Water donates electrons and cations (2H+) to, NADP+., Plants utilise less than 1% of water absorbed by, them in photosynthesis., , l, l, l, l, l, l, l, l, , l, , l, l, l, l, l, l, , Mg is associated with the synthesis of chlorophyll, molecule., Electron carriers namely ferredoxin and, plastocyanin contain iron, and copper respectively., Mn++ and Cl– ions are useful for photolysis of, water., Rate of photosynthesis decreases when there is, deficiency of elements like Mg+, Mn+, Cl–., Radiant energy is converted into chemical energy, by chlorophyll., Chlorophyll–less mutant plants are called albinos., Albinos cannot survive long due to the, nonproduction of carbohydrates., Accumulation of carbohydrates decreases the rate, of photosynthesis (due to nonavailability of space, for new molecules)., As the leaf expands the stomata will be opened to, the external atmosphere. Rate of photosynthesis, increases due to the entry of CO2., Necessity of CO 2 for photosynthesis can be, demonstrated by Moll’s half leaf experiment., Necessity of light for photosynthesis can be, demonstrated by light screen experiment., Necessity of chlorophyll for photosynthesis can be, demonstrated by Croton leaf experiment., Liberation of O2 during photosynthesis can be, demonstrated by Hydrilla funnel experiment., Presence of starch can be tested by iodine test., Osmotically inactive form of photosynthetic product, is starch., , IMPORTANCE OF PHOTOSYNTHESIS, l, , l, l, , l, , l, , l, , Photosynthesis is the fundamental synthetic process, present in green plants. It is an anabolic or, constructive process., All organisms depends directly or indirectly on, photosynthesis for their food and energy needs., Entire oxygen of the atmosphere is derived from, photosynthesis. It is useful for respiration of, organisms., Photosynthesis is helpful in maintaining, percentage of O2 and CO2 constantly in the, atmosphere., It is the only biochemical process in which light, energy is first converted into chemical energy, and then stored as potential energy in, carbohydrates., Molecular O2 released from photosynthesis is also, utilized in making ozone (O3) in the outer layer of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ĺŐŚŐřťňŚĺĚřĽř, , l, , l, , atmosphere. The ozone layer acts as screen and, helps in stopping the highly destructive ultraviolet, (UV) rays from reaching the earths., The carbohydrates produced during photosynthesis, are used by plants and animals to synthesize organic, acids proteins, fats, nucleic acids, hormones,, pigments, vitamins, alkaloids and other metabolites., Photosynthesis consumes atmospheric carbon, dioxide which is being continuously added by the, respiration of organisms and burning of organic, fuels. Thus, this process acts as purifier of, atmosphere., , l, l, l, l, , l, l, , PHOTORESPIRATION, l, , l, l, l, l, , l, l, l, , Light induced CO 2 liberation from a, C2 compound (glycolic acid) of dark phase is called, photorespiration., Photorespiration occurs in green cells only., Photorespiration is absent in C4 plants and is, present in C3 plants., Photorespiration involves three cell organelles –, peroxisomes, chloroplasts and mitochondria., This process is considered to nullify the result of, photosynthesis as no ATP and NADPH 2 is, produced., During photorespiration loss of carbon takes place, in the form of CO2., When the concentration of O2is more than that of, CO2 then RuBP oxygenase adds O2 to RuBP., RuBP is converted into one molecule of PGA and, , l, , l, l, l, , l, , l, , 351, , one molecule of phosphoglycolic acid., Phosphoglycolic acid is dephosphorylated to, glycolic acid., Glycolic acid then enters the peroxisome., Glycolic acid acts as a substrate for, photorespiration., Glycolic acid undergoes oxidation to form, glyoxylic acid and hydrogen peroxide. Enzyme is, glycolic oxidase., Enzyme useful for the breakdown of H2O2 into water, and oxygen is catalase., Glyoxylic acid is converted into glycine by, transamination in the presence of enzyme, glyoxylate aminotransferase. Glycine then enters, the mitochondrion., Two molecules of glycine by loosing one molecule, of CO2 are converted into serine. Enzyme involved, is glycine decarboxylase., In mitochondria two glycine molecules react to, produce 1 molecule of serine, CO2 and NH3., Liberation of CO2 occurs in the mitochondrion., Serine is deaminated to hydroxypyruvate in, peroxisome by transaminase and glyceric acid is, also formed., Photorespiration is also called glycolate pathway., Formation of PGA from two carbon intermediate,, glycolic acid is called glycolate pathways., Glyceric acid is transported out of peroxisome into, chloroplast where it forms 3PGA by ATP.The PGA, is used in photosynthetic carbon reduction cycle.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 352, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 37, , Respiration in Plants, l, , l, , l, l, , l, l, , l, l, , l, l, , All the cellular activities are grouped into two, categories anabolism (biosynthetic activities of, the cell) and catabolism (breaking up processes of, the cell)., The anabolic activities are endergonic (energy, dependent), while catabolic activities are usually, exergonic (energy producing)., The sum total of catabolic and anabolic reactions, occurring at any time in a cell is called metabolism., Respiration is an exergonic and catabolic physico, chemical process which involves the exchange of, environmental oxygen and body carbon dioxide, through a liquid medium and the oxidation of, glucose inside the mitochondria to produce energy, which is partly stored in the high energy bonds (~), of ATP molecules as biologically useful energy., The reaction for respiration is –, C6H12O6 + 6O2 ® 6CO2 + 6H2O + Energy., Biological useful energy is in stored forms and is, must because –, –, Released energy may not be required, immediately., –, Sites of endergonic processes may be away, from the sites of exergonic processes., –, It provides a quick source of energy when, required, so ATP is commonly called energy, currency., The dry weight of a plant decreases due to, respiration., Respiration is a biological oxidation process. It, resembles oxidation in certain respects and differs, with it in releasing energy in a stepwise manner., All living organisms (except viruses) respire., Carbon present in the living cells undergoes, combustion in presence of atmospheric oxygen and, is exhaled out in the form of CO2. Hydrogen is, present in the form of water vapour. This was stated, by father of modern chemistry Lavoisier., , l, , l, , l, , l, , l, , l, , Respiration is a type of metabolism which includes, the following four important points., –, Energy is liberated through biological, oxidation from the food collected by the, organism and the energy will be utilised by, that living system., –, End products are not important. Types of, energy and their utilization is very important., –, In aerobic respiration energy of the food is, totally liberated due to complete biological, oxidation of substrate. A part of energy is, liberated in anaerobic respiration due to, partial oxidation of the substrate., –, Biological oxidation depends upon factors, present in the living cells., The organic substances (i.e., carbohydrates, fats,, proteins, etc.) are broken down to release energy, by the process of cellular respiration., Cellular respiration may be divided into two, cateogries depending upon the availability of, atmospheric oxygen – aerobic (presence of oxygen), and anaerobic respiration (absence of oxygen)., The breakdown of respiratory substrates provides, carbon skeleton for the synthesis of a large number, of other essential plant products, such as, polysaccharides, proteins, fats, nucleic acids,, pigments, cytochromes etc., Thus, the same respiratory process which acts as, catabolic pathway for respiratory substrates also, acts as anabolic pathway for the synthesis of various, intermediary metabolic products and secondary, metabolities., Thus, it is called as amphibolic pathway rather, than as a catabolic pathway., , RESPIRATORY SUBSTRATES, l, , Any organic substance which can be oxidised in, respiration is known as respiratory substrate.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 353, , ☻ĚřőĽŕŐň– Ľň– ▓ńďňŚř–, l, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, l, , l, , Respiratory substrates are carbohydrates (starch,, sucrose, fructose and glucose), proteins, fats and, organic acids., All organic substances (excepting glucose) should, necessarily undergo digestion before their, participation in respiration., A respiratory substrate which does not require, digestion and which can directly participate in, respiration is glucose., The ratio of the volume of CO2 liberated to the, volume of oxygen absorbed per molecule, during respiration is called respiratory quotient, (RQ)., The value of RQ indicates the type of respiratory, substrate., RQ value for carbohydrates is 1 or unity as, amounts of CO 2 and O 2 are equal because, carbohydrates contain equal amounts of carbon and, oxygen., Fats are poor in oxygen. So they need more O2 for, their oxidation. Therefore RQ value for fats is less, than 1., RQ value for proteins will be approximately 0.8, or 0.9. Because proteins contain more oxygen, when compared to fats and less O2 when compared, to carbohydrates., As RQ value for fats and proteins is less than 1 so, more oxygen is absorbed and less CO2 is liberated, in oxidation of fats and proteins., RQ value in succulents is zero. In succulents, Opuntia (Cactaceae), Bryophyllum (Crassulaceae), carbohydrates are partially oxidised to malic acid., CO2 is taken back and is fixed by RuBP carbroxylase, in Calvin cycle., RQ value for organic acids is more than 1., Because they are rich in oxygen, more CO2 is, liberated and less O2 is absorbed in oxidation of, organic acids., RQ value is infinite during anaerobic respiration, because there is no utilisation of O2 in this process., Carbohydrates are converted into fats during, maturation of certain seeds. During this, conversion the liberated oxygen will be utilised, for respiration., The value of RQ in different parts of the plant falls, between 0.97 and 1.17 (near about 1 which is the, RQ for carbohydrates). From this it is clear that, , l, , l, l, , l, , l, , l, , l, , mostly sugars are the respiratory substrates in, plants., Since germinating seeds contain only one type of, reserve food their RQ value indicates the nature, of the food actually stored in the seeds., RQ value is measured with the help of double, respiroscope., External factors affecting respiration are –, oxygen concentration, CO2 concentration, mineral, and water availability etc. Respiratory substrate also, effect respiration., At low temperatures (below 0°C) the rate of, respiration is minimum. Hence fruits and, vegetables are stored at low temperature for, preservation., Depending upon the substrates employed,, respiration is of two types – floating respiration, & protoplasmic respiration., Floating respiration is that respiration which, employs energy foods’ as substrates (Two energy, foods are carbohydrates and fats)., Protoplasmic respiration is that respiration which, employes proteins as respiratory substrate. As, proteins are rarely stored in the cells, protoplasmic, respiration uses cellular proteins. This disturbs, metabolism and cellular machinery causing, permanent injury and even death of the cells., , COMPENSATION POINT, l, , l, , l, l, , l, , l, , Compensation point is the point reached in a plant, when the rate of photosynthesis is equal to the rate, of respiration., This means that the carbon dioxide released from, respiration is equivalent to that which is taken up, during photosynthesis., The compensation point is reached as light intensity, increases., Respiratory rate increases with an increase in, temperature from 0 to 40°C. But the optimum, temperature for respiration is 2535°C (at which, most of the metabolic activities of plants takes, place)., At high temperature (above 50°C) the respiratory, rate decreases because of the denaturation of, enzymes., Photosynthesis occurs in the presence of light and, helps in the preparation of respiratory substrate.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 354, , ŕďőĽę– ĐĽŐńŐĹť, , AEROBIC RESPIRATION, l, , l, l, , l, l, , l, l, , Complete biological oxidation of the respiratory, substrate with the help of atmospheric oxygen is, known as aerobic respiration., Organisms which carry out aerobic respiration are, called aerobes., The process of aerobic respiration can be, represented by the following equation –, C6H12O6 + 6O2 + 6H2O ® 6CO2 + 12H2O + 673Kcal, 686 Kcal (2870 kJ) is energy released per mole of, glucose., There are two types of aerobic respiration –, common pathway and pentose phosphate, pathway., It is known so because one of its step (glycolysis),, is common to it as well as to anaerobic respiration., C ommon pa th wa y occu r in th ree step s , glycolysis, Krebs cycle and terminal oxidation, (electron tran sp ort cha in a nd oxid ative, phosphorylation)., , Glycolysis or Embden - Meyerhof Parnas or emp, pathway, l, , l, l, , l, l, , l, l, l, , l, l, , The breakdown of a sweet substance namely, glucose (glycogen) into two molecules of pyruvic, acid is called glycolysis., Glycolysis is common phase in both aerobic and, anaerobic respiration., Glycolysis occurs in all living organisms and in all, types of respiration. Hence James called it as core, respiration. This is also known as fundamental, respiration., Site of glycolysis is cytoplasm (cytoplasmic matrix, of a living cell)., The reduction of the glucose during glycolysis, produce compounds for the synthesis of protein,, fats and nucleic acid., Most of the steps of the glycolysis are reversible., Glycolysis may be divided into two phases, a, preparatory phase and an oxidative phase., In the preparatory phase breakdown of glucose, and low energy phosphorylation occurs, and, energy is used. In the oxidative phase high energy, phosphate bonds are formed and energy is stored., All reserve substances first undergo hydrolysis and, are finally converted into glucose., In majority of the organisms glucose acts as the, respiratory substrate., , l, l, , l, l, l, l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, l, l, , In glycolysis one molecule of glucose is converted, into two molecules of pyruvic acid., The sequence of reactions in glycolysis was traced, out by Embden Meyerhof Parnas. Hence, glycolysis is also called EMP pathway., Glucose is to be excited before it is biologically, oxidised through glycolysis., Excitation of glucose (oxidative phosphorylation), takes place by transphosphorylation., Glucose is phosphorylated to glucose6 phosphate, by hexokinase and ATP., Glucose6phosphate is converted into its isomer, fructose6phosphate (isomerisation) by hexose, phosphofructokinase., If fructose is there in hydrolytic products of, carbohydrates it is also phosphorylated to fructose, 6phosphate by fructose phosphotransferase just, like glucose., Fructose6phosphate is phosphorylated to fructose, 1,6 biphosphate by phosphofructokinase and, ATP., Though fructose 16 biphosphate is in the excited, state it is not suitable for biological oxidation., Therefore, the chemical bond between third and, fourth carbon atoms is to be broken down by, ketosephosphate aldehylase (Aldolase)., The products of fructose, 1,6 biphosphate are, glyceraldehyde 3 phosphate (GAP) and, dihydroxyacetone phosphate (DHAP)., (a) GAP and DHAP are trioses and isomers., (b) GAP and DHAP are interconverted into one, another by GAP ketol isomerase (triose phosphate, isomerase)., The substance which is suitable for biological, oxidation and which undergoes first biological, oxidation in respiration is GAP., GAP is phosphorylated and also biologically, oxidised to 1,3 diphosphoglyceric acid., Consumption of inorganic phosphate (phosphoric, acid, H3PO4) in this biological oxidation is most, important since this phosphate is involved in ATP, synthesis in the next reaction., This first biological oxidation reaction is catalysed, by GAP NAD oxidoreductase., NAD+ (Nicotinamide Adenine Dinucleotide) acts, as coenzyme in above oxidation., NAD+ is the universal hydrogen acceptor., H2 is liberated due to biological oxidation.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚřőĽŕŐň– Ľň– ▓ńďňŚř–, l, , l, , l, l, l, l, , l, l, l, , l, , l, l, l, l, , l, , l, l, l, l, , Oxygen functions as the terminal acceptor of, electrons and is reduced to water along with the, hydrogen atoms., Reduced coenzymes (coenzyme1, II and FAD) do, not combine directly with the molecular O2. Only, their hydrogen or electrons are transferred, through various substances and finally reach O2., The substances useful for the transfer of electron, are called electron carriers., Enzyme useful for the oxidation of coenzyme is, NADH dehydrogenase., Flavo proteins receive hydrogen from coenzyme, I or II and get reduced., CoQ receives hydrogen from flavoproteins and, gets reduced. CoQ also receives hydrogen from, reduced FAD and gets reduced., The splitting of hydrogen into 2H+ and 2e¯ takes, place at CoQ (also known as ubiquinone; U.Q)., Protons are liberated into the surrounding, medium., Only electrons are transferred through cytochromes, (Cyt b, Cyt c1,c2, a, a3) and finally reach molecular, O 2., Atoms of iron exist in 2 forms – ferric and ferrous., Electrons are received by ferric form., 2Fe+++ + 2e¯ –® 2Fe++, Ferric form, Ferrous form, Enzyme useful for terminal oxidation is, cytochrome oxidase or terminal oxidase., Both cytochrome a and a3 form a system called, cytochrome oxidase., Copper is also present in Cyt a3 in addition to, iron., The molecular oxygen that has accepted electrons, now receives the protons that were liberated into, the surrounding medium to give rise to a molecule, of water., The electrons are transferred from one electron, carrier to another electron carrier because of the, differences in redox potentials among the, carriers., The tendency of electron carrier to receive or donate, electrons is known as redox potential., Electrons lose some amount of energy during their, transfer through electron carriers., The liberated energy is utilised for the synthesis of, ATP from ADP and Pi., Synthesis of ATP (from ADP and inorganic, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, l, , l, l, l, , 359, , phosphate) during oxidation is called oxidative, phosphorylation., ATPsynthetase becomes active in ATP formation, only where there is a proton gradient having higher, concentration of H+ or protons on the F0 side as, compared to F1 side (chemiosmotic hypothesis of, Peter Mitchel, 1961, Nobel Prize in 1978)., 2 mols. of NADH2 produced in glycolysis in, cytoplasm have to go inside mitochondria for, oxidative phosphorylation but mitochondrial, membrane is not permeable to NADH2 and hence, the electrons or Hatoms of NADH2 go inside, mitochondria with the help of electron shuttles., Two types of shuttles are common – malate, aspartate shuttle and glycerol phosphate shuttle., Malate asparate shuttle When this electron, shuttle occurs, transfer of electrons from NADH2, in cytoplasm occurs to NAD inside the, mitochondria. This is more efficient and results in, production of 38 ATP molecules., In glycerolphosphate shuttle the transfer of, electrons from NADH2 in cytoplasm occurs to FAD, inside mitochondria and it results in production of, 36 ATP molecules., Oxidative phosphorylation of respiration is of two, kinds – substrate level phosphorylation (SLP), and chain level phosphorylation (CLP)., The oxidative phosphorylation occurring at the level, of respiratory chain is called chain level, phosphorylation., 3 ATP and 1 H2O are formed by the oxidation of, a molecule of reduced Coenzyme I or II, between, pyridine nucleotides and flavoproteins, between, cyt b and cyt c1, between cyt a and a3., 2ATP and 1 H2O are formed by the oxidation of, a molecule of reduced FAD through electron transport, between cyt b and cyt c1, between cyt a and a3., Chain level phosphorylation takes place in, oxysomes., No. of ATP formed by oxidation of glucose during, glycolysis is 10 (substrate level phosphorylation =, 4, chain level phosphorylation = 6)., No. of ATP utilised during glycolysis is 2., Net gain of ATP through glycolysis is 8 (When, glucose is completely oxidised)., Number of ATP formed by complete oxidation of, each molecule of pyruvic acid is 15. Therefore for, 2 molecules of pyruvic acid is 30.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 360, , l, l, l, l, l, l, , l, l, , Number of ATP formed during SLP = 2 and, CLP = 28., No. of ATP formed by complete oxidation of a, molecule of glucose (180 gm) is 40., No. of ATP utilised during respiration is 2., Net gain of ATP during aerobic respiration is 38., No. of ATP formed through SLP during aerobic, respiration = 6 (4 + 2), No. of ATP formed through CLP during aerobic, respiration = 34 (6 + 28), As a result of biological oxidation of coenzymes, chemical energy reserve is formed in a living, cell., Energy liberated by the removal of terminal, phosphate from ATP is 8 k cal., Most of the ATP molecules are stored in, mitochondria hence mitochondria are often called, as power houses of the cell., , Glucose 6 phosphate, dehydrogenase, CO2, Hexose phosphate isomerase, , l, , ŕďőĽę– ĐĽŐńŐĹť–, l, , l, , l, , ATP is utilised in driving various metabolic, activities (absorption of salts and other metabolic, activites)., Krebs cycle and respiratory chain are useful for the, biological oxidation of carbohydrates (eg. starch),, fats and proteins., Carbohydrates, fats and proteins enter the Krebs, cycle in the form of acetyl CoA., , HEXOSE MONOPHOSPHATE PATHWAY, (HMP) OR PENTOSE PHOSPHATE, PATHWAY (PPP), l, , It is alternate method of aerobic respiration which, occurs in the cytoplasm of mature plants cells, and accounting for 60% of total respiration in liver, cells and also occur in adipose tissue and lactatic, mammary glands., , Glucose 6 phosphate, NADP, NADPH, , +, , 6 phosphogluconate, NADP, , Gluconate 6 phosphate, dehydrogenase, , NADPH, , +, , Ribulose 5 phosphate, Pentose phosphate isomerase, Ribose 5 phosphate, , Pentose phosphate epimerase, Xylulose 5 phosphate, , Transketolase, Glyceraldehyde 3 phosphate, , Sedoheptulose 7 phosphate, , Transaldolase, Fructose 6 phosphate, , Erythrose 4 phosphate, Transketolase, Glyceraldehyde 3 phosphate, Figure : Pentose phosphate pathway
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚřőĽŕŐň– Ľň– ▓ńďňŚř–, l, , l, , l, l, , l, , l, l, , l, , l, l, , l, l, l, , l, , l, , The pentose pathway is also known as the, phosphogluconate pathway. Since, this pathway, metabolizes glucose 6phosphate by reactions that, bypass the reactions of glycolysis, it is also known, as hexose monophosphate shunt (HMP shunt)., The first enzyme in this pathway, i.e. glucose, 6phosphate dehydrogenase was discovered by, Otto Warburg in 1931. Later the complete cycle, was elucidated by Fritz Lipmann, Frank Dickens, and Bernerd Horecker., Normally glucose during aerobic respiration forms, CO2 and H2O., The glycolytic pathway is not the only route, available for the oxidation of sugars in plant cells., Oxidative PPP or HMP by sharing common, metabolites can also do this work., In PPP, glucose 6 phosphate (6C) formed in, glycolysis or photosynthates formed during, photosynthesis are oxidised to form 6 , phosphoglyconate., This step requires the enzyme glucose 6, phosphate dehydrogenase to release NADPH., 6 phosphogluconate in presence of enzyme 6 , phosphogluconate dehydrogenase forms 1 molecule, of ribulose 5 phosphate., It can further form glycolytic intermediates like, glyceraldehyde 3 phosphate and fructose 6 , phosphate., All reactions of PPP occur in cytoplasm of cell., It is a multifunctional pathway which is primarily, meant to generate reducing power in the form of, NADPH which serves as a hydrogen and electron, donar in a number of reductive biosynthetic, pathways, especially of fatty acids and steroids., It occurs in the extramitochondrial cytoplasm, which has all the enzymes of HMP., In this, hexoses are converted into pentoses,, especially ribose 5 phosphate., It is also called direct oxidative pathway because, in this C1 of glucose is oxidised first. (In, glycolysis, C – 3 and C – 4 are first oxidized)., The co enzyme used in oxidative reactions of HMP, is NADP+ which is reduced to NADPH + H+ (In, glycolysis, H acceptor used is NAD+)., 12 pairs of hydrogen atoms are eventually, transferred to oxygen in this pathway, yielding 38, ATP. Of these, 1 ATP must compensate for the ATP, used in converting one molecule of free glucose to, , 361, , glucose 6phosphate. Hence the net yield is 35, ATP which compares favourably with the 38 ATP, obtainable from glycolysis and TCA cycle., , ANAEROBIC RESPIRATION, l, , l, , l, l, , l, , l, l, l, l, , l, , l, , l, l, , l, , Partial biological oxidation of glucose molecule, without utilising oxygen is called anaerobic, respiration., Anaerobic respiration is a temporary process in, higher plants and permanent process in micro, organism i.e. bacteria and Yeast., Anaerobic respiration takes place in cytoplasm., Net equation for anaerobic respiration is, C6H12O6 ® 2CO2 + 2C2 H5OH + 17.8 K cal +, Glucose, Ethyl alcohol 56/ 22 K cal, With the formation of pyruvic acid, respiration in, anaerobes can be considered complete because, pyruvic acid will not undergo biological oxidation, instead it undergoes decarboxylation., Glycolysis, C6H12 O6 + 2NAD+ + 2ADP + 2Pi ¾®, 2CH3 COCOOH + 2NADH + 2H+ + 2ATP, Pyruvic acid decarboxylation, 2CH3COCOOH ¾® 2CO2 + 2CH3CHO, Acetaldehyde reduction, 2CH3CHO + 2NADH + 2H+ ® 2C2H5OH+ 2NAD+, , End products of anaerobic respiration are 2CO2, (carbon dioxide) and 2C2H5OH (ethanol)., Anaerobic respiration is intracellular respiration., Anaerobic respiration is harmful to plants because, of the production of ethyl alcohol (ethanol)., Fermentation of sugars takes place by some, microorganisms. This was first stated by Louis, Pasteur., Buchner accidentally discovered that, the juice, extracted from the yeast cells has the ability of, bringing out fermentation. This discovery enabled, the study of fermentation without the involvement, of living system., In microorganisms, the term anaerobic respiration, is replaced by fermentation. This term was coined, by Cruickshank (1897)., Fermentation means preparation of wine from, sugars or sugary substances on an industrial scale., Gay Lussac is the discoverer of fermentation. He, indicated that alcohol is formed due to a chemical, change of glucose., Depending upon the end product the fermentation
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 362, , l, l, l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , is of various types viz alcoholic fermentation,, lactic acid fermentation, citric acid fermentation, etc., Alcoholic fermentation is brought about by yeast, cells (Saccharomyces) sp., Enzyme useful for alcoholic fermentation is, zymase., Yeast cells cannot ferment starch because they, lack amylase., Alcoholic fermentation resembles the anaerobic, respiration of higher plants but differs from it in, two aspects – no glycolysis and no ATP, formation., Alcoholic fermentation is useful in alcohol industry, and bakery., Lactic acid fermentation is brought about by, , l, , l, l, , l, l, l, l, , bacterium Lactic acidi (anaerobic), B.acidi lactici, (aerobic)., Saccharomyces cerevisiae is Brewer’s yeast. Wine, yeast is Saccharomyces ellipsodiens which perform, alcoholic fermentation., Lactic acid fermenation is used in dairy industry., Butyric acid fermentation is brought about by, Clostridium butyricum (a bacterium). This, fermentation turns butter rancid., Acetic acid fermentation is brought about by a, bacterium Acetobacter aceti., It is useful in vinegar industry., Citric acid and oxalic acid fermentation is, brought about by Aspergillus niger (Fungus)., Organisms carrying on fermentation are Yeast,, Clostridium, Acetobacter, Aspergillus., , Some important points, –, –, –, –, , –, –, –, –, –, , Not only animals but plants also exchange CO2, with O2. It was proved by Ingenhousz., Sachs confirmed that all exergonic reactions form, a component of respiration. Sachs divided the entire, process of respiration into two types., Slites and Leach explained that all reactions in, which complex organic substances are broken down, into simpler ones are respiratory in nature., The book entitled cellular respiration was written, by Meldrum on the basis of a concept that, molecules of cells are combusted through, oxidation., All respiratory intermediates are the precursors, for the synthesis of protoplasm.This was clarified, by James., Shifting from anaerobic respiration to aerobic, respiration due to availability of O2 is called Pasteur, effect., Anaerobes which can tolerate the presence of, oxygen are called facultative aerobes. (They, continue their anaerobic respiration), eg : yeast., Anaerobes which cannot survive in atmospheric, oxygen are called obligate anaerobes. Eg : Bacillus, botulinus., Mg++ and K+ act as cofactors of the enzymes., , –, –, –, –, –, –, –, –, –, –, –, , Increase in rate of respiration due to high salt, concentration is called salt respiration or anion, respiration., Water acts as the medium for respiratory enzymes, and also participates in respiration. Hydration of, tissues increases the rate of respiration., The water formed in a metabolic process is called, metabolic water., Rate of respiration in measured by Ganong's, respirometer., Fermentation can be demonstrated by Kuhne's, Vessel., Liberation of heat is demonstrated by Dewar's flask, experiment., Chemical useful for absorption of CO2 during, respiration is KOH (potassium hydroxide)., Mercury is used in anaerobic respiration, experiment because it does not react with CO2., During 24 hours there is a time when plants neither, give carbon dioxide nor oxygen. This is the time, of twilight., Anaerobic respiration was first reported by, Kostychev., Endoparasites respire without oxygen.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ, , 363, , Chapter 38, , Nutrition & Digestive, System, NUTRITION, l, , l, l, , l, , l, , l, l, l, , The process by which living organisms obtain those, substances which are required for their growth and, maintenance and for meeting their energy needs is, called nutrition, and the substances are called, nutrients of foods., Organisms have two modes of nutrition :, autotrophic and heterotrophic., In autotrophic nutrition, green plants, some, bacteria and protists utilise energy of sunlight for, preparing organic food in their own body from, simple inorganic materials. These organisms are, called phototrophs or autotrophs., Some bacteria use energy released by the oxidation, of certain chemical substances for the preparation, of food. They are called chemotrophs., In heterotrophic nutrition animals obtain organic, food materials by consuming bodies or products of, other plants or animals, such organisms are called, heterotrophs., Heterotrophic nutrition is of four types–, holozoic, saprozoic, parasitic and symbiotic., In holozoic nutrition, the solid food is ingested, (taken in), digested and then absorbed into the cells., Holozoic animal may be herbivores (plant eaters,, e.g. cow, rabbit), carnivores (flesh eaters, e.g. dog,, tiger), omnivores (both plant and animal eaters,, e.g. cockroach, man), insectivores (insect eaters,, e.g. toads, lizards), frugivores (fruit eaters, e.g., monkeys, birds), sanguivores (feed on blood of, vertebrates, e.g. female Anopheles mosquito,, leeches), detrivores (feed on decaying organic, matter, e.g. earthworms) and fluid feeders (feed, on fluids from plants, e.g. butterflies, male, mosquitoes)., , l, , l, , l, , l, , l, , l, , l, , l, , In saprozoic nutrition, organisms obtain nutrients, from decaying organic materials after digesting the, same with the help of enzymes. A few animals (e.g., spider, housefly, etc.) secrete digestive enzymes, directly onto their food, which are dead or decaying, matters and then suck the digested food., In parasitic nutrition liquid food material is, obtained by the parasite from the body of host, e.g., Plasmodium, Ascaris., In symbiotic nutrition often two organisms live in, association and derive nutrition from each other,, e.g. Escherichia coli in human intestine synthesizes, vit. B12 and in return obtain simpler food from, human intestine., Holozoic nutrition involves four steps. These are –, ingestion (feeding of the food), digestion (breaking, down of complex organic molecules into simple, molecules by hydrolysis), absorption (uptake of, simple diffusable molecules by the digestive tract), and egestion (passing out of indigestible material, through the anus)., In different animals ingestion occurs by different, process on the basis of which they are classified, into fluid feeder animals, filter feeder animals, and macrophagous animals., Ingestion occurs in fluid feeder animals by, diffusion (eg. parasitic protozoans), pinocytosis, (eg. sanguivorous animals like leech, mosquitoes), etc., Filter feeder animals, also called microphagous, animals are those animals which takes small sized, food particles., Ingestion occur in microphagous animals by, maintaining a water current which bring, microscopic organisms. Examples are, pseudopodial feeder (Amoeba), ciliary feeder
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 364, , l, , l, , l, l, l, , l, , l, , l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , (Paramecium), flagellar feeder (sponges), mucoid, feeder (Nereis) and tentacular feeder (Hydra)., Macrophagous animals feed on large sized food, particles and have different structure to capture and, ingest the food. Eg. (i) Tentacles with batteries of, cnidoblasts in coelenterates. (ii) Eversible and sticky, tongue (eg. frog, toad, wall lizard) to capture insects, with differently adapted teeth, like well developed, incisors in rabbit and well developed canines, (tearing teeth) in carnivores (eg. lion, tiger etc.), Digestion, essentially a hydrolytic process, is, carried out by various enzymes using water, molecules for cleavage., The enzymes which bring about digestion are called, hydrolases., Digestion may be intracellular (within the cell) or, extracellular (in digestive cavity)., The unicellular animals like Amoeba and porifers, (sponges) digest the food within the cells and show, intracellular digestion., The cnidarians (e.g. Hydra, Aurelia etc.) have sac, like coelenteron or gastrovascular cavity, which is, lined by various type of endoderm cells. The food, is partially reduced to small fragments by, extracellular digestion by the enzymes secreted, by the gland cells of endoderm. The small fragments, of the food are ingested by nutritive cells and, complete the digestion intracellularly., The free living platyhelminthes (e.g. Planaria) also, employ both types of digestion i.e. intracellular, and extracellular., Nutritional requirements are basically supplied in, the form of nutrients which may be organic and, inorganic., Food is any substance (especially solid) that can, be taken into the body of an animal and plant to, maintain its life by providing one or more nutrients, for supply of energy and materials., The major constituents of food are carbohydrates,, proteins, fats, vitamins, minerals and water., If all these components are present in optimum, proportion and quantity for maintaining the body, in perfect state of health, activity and development, then the food is called balanced diet., According to their utility in the body, these, nutrients are divided into four categories – energy, producers (carbohydrates, fat); body builders, (proteins), metabolic regulators (vitamins and, , Table : Main component of food and their sources., Carbohydrate Flour, rice, potatoes, corn, vegetables,, bread etc., Protein, Milk, eggs, meat, fish, beans, peas,, nuts, pulses and cereals etc., Fats and Oils Groundnut oil, coconut oil, sunflower, oil, ghee, butter, milk, cheese, meat,, egg, fishes like cod and herring., Water, Liquids (water, juices, milk) and some, fruits like lettuce, orange, melons., Vitamins, Balanced diet provide all essential, vitamins for body health., Minerals, Dairy products, vegetables, fruits,, meat, chicken etc., , l, l, l, , l, , l, , l, l, l, , l, l, l, , l, , minerals and H2O) and hereditary substances, [nucleic acids (DNA, RNA)]., Balanced diet should have protein 1/5, fat 1/5 and, carbohydrate 3/5., Carbohydrates provide energy and heat., 1 gm of carbohydrate yield 4 kcal of energy on, oxidation in the body. It is called its physiological, fuel value., Carbohydrates are more suitable for the, production of energy in the body than proteins, and fats, because carbohydrates contain relatively, more oxygen and require less molecular oxygen, for their oxidation., Athletes, labourers doing heavy work and, mountaineers should live on high carbohydrate, diets., Protein are essential for body growth and repair., Basic unit or smallest structural unit of proteins, are amino acids., Amino acids absorbed from the food are used to, synthesise structural proteins (collagen, elastin, keratins), enzymes and hormones, (pepsin, trypsin,, insulin), haemoglobin, skin pigment, purines,, pyrimidines and blood proteins., The physiological fuel value of protein is 4 kcal., The dietary requirement of proteins rises during, pregnancy and lactation, growth and tissue repair., Nutritionally amino acids are of two types–, essential (not synthesized in body and must be, included in diet) and nonessential (can be, synthesized in body from carbohydrate metabolites)., Essential amino acids are 8 in number
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ, , l, , l, , l, , l, l, l, , l, l, , l, , l, , l, l, l, , l, , (methionine, threonine, tryptophan, valine, leucine,, isoleucine, lysine and phenylalanine) and non, essential amino acids are 12 in number (alanine,, proline, glycine, aspartic acid, tyrosine, serine,, cysteine, asparagine, glumatic acid, glutamine,, arginine and histidine)., Semiindispensible amino acids are formed slowly, and are required only during periods of rapid tissue, growth. Eg. arginine and histidine., Twenty amino acids, linked together by peptide, bonds, make all different proteins required by the, body., If amino acids are used for energy liberation (as, during starvation), ketones are formed. The, phenomenon is called ketosis or acidosis., Fats are used as stored food to be used in the, production of energy., Calorific value of fat is 9.45 kcal means 1gm of, fat yield 9.45 kcal energy on oxidation in the body., An essential fatty acid (EFA) is one which must, be included in the diet because it cannot be made, in the body., Linoleic acid and alpha linolenic acid are the two, most essential fatty acids., Saturated fatty acid (general formula CnH2nO2), do not possess double bonds in their carbon chains,, eg. palmitic acid., Unsaturated fatty acid (general formula, CnH2n–2xO2) possess one or more double bonds in, their carbon chains., Linoleic acid and linolenic acid are both poly, unsaturated fatty acids (PUFAs) and help in –, forming the structure of membrane, transport,, breakdown and excretion of cholesterol, normal, development and functioning of retina and brain., Free fatty acid (FFA) circulate in blood in, combination with albumin., Lumin discovered vitamins and the term vitamin, was coined by Casimir Funk (1912)., Vitamins are nonenergy producing organic, substances which are vitally essential in traces for, proper use of macronutrients in cell metabolism, and hence for proper growth and function., On the basis of solubility, vitamins are divided, into 2 main categories water soluble vitamins, (vitamin B complex and vitamin C) and fat soluble, vitamins (A, D, E and K)., , l, l, , l, l, l, l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , 365, , Fat soluble vitamins are absorbed in the alimentary, canal without any breakdown., Vitamin D (steroid vitamin) is synthesized in skin, cells in sunlight from 7dehydrocholesterol (i.e., provitamin D3)., Vitamin often acts as coenzymes., During prolonged fasting first carbohydrates are, used up, followed by fat and proteins towards end., Apart from organic chemicals, human body needs, inorganic chemical elements, called minerals., Depending on the necessity, minerals can be, divided into – macroelements (required in amount, more than 1 gm) and microelement (required in, trace amount less than 1gm)., Both macroelements and microelements (minerals), are found in milk, cereals, fresh fruits and, vegetables, sea food etc., Basal metabolic rate (BMR) is the minimal caloric, requirement needed to sustain life in a resting, individual. For normal adult it is 1600 Kcal/day., Routine metabolic rate (RMR) is the energy, requirement of a moderately active person. RMR, is 2800 Kcal for adult males and 2200 Kcal for, adult females., Sprue, caused by deficiency of folacin (folic acid), is characterised by ulceration of mouth,, inflammation of bowel, inability to absorb, (especially fats), diarrhoea, weakness and anaemia., Anorexia nervosa is sometimes referred to as, ‘slimmers’s disease’ (literally means “loss of, appetite through nervous causes)., Disorders of nutrition are of two types–, malnutrition and overnutrition., Malnutrition (PEM – protein malnutrition) is, primarily due to an inadequate intake of food, (particularly protein) both in quantity and quality, and infections etc, which increases requirements, for calories, proteins and other nutrients, while, decreasing their absorption and utilization. It, generally affects infants and children., Two very commonly occurring diseases due to, protein malnutrition are – kwashiorkar and, marasmus., Symptoms of kwashiorkar are retarded growth of, body and brain, protruding belly, oedema, slender, legs, bulging eyes and diarrhoea., Symptoms of marasmus are mental retardation,, lean and weak body, dry thin and wrinkled skin as
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 366, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Important vitamins, their functions & deficiencies., Name, , Functions, , Vitamin A, or, Retinol, , Regulates epithelial growth of tissue,, promotes vision by regenerating visual, purple, a precursor for synthesis of, rhodopsin., Regulates calcium and phosphorus, metabolism; also for normal growth of, bones and teeth., , Vitamin D, or, Calciferol, Antirachitic, Vitamin E or, Tocopherol, Antisterility, Vitamin K or, Antihaemorrhagic, , Essential for formation of prothrombin, which helps in coagulation and maintains, time of coagulation of blood., Vitamin B complex Essential for growth, carbohydrate, metabolism digestion, nervous system,, B1 (Thiamine), decarboxylation of pyruvic acid and, or, coenzyme activities., Aneurin or, Antineuritic, Essential for tissue oxidation, healthy skin,, Riboflavin (B2), muscles, carbohydrate and fat metabolism,, or Vitamin G, normal vision., Nicotinic acid, B3 Essential for fat, carbohydrate and, protein metabolism, healthy skin,, (or Niacin or, coenzymatic functions of cellulose., Antipellagric) or, Vitamin PP, Essential for growth, formation of blood, Folic acid, B9, cells, DNA and also acts as coenzyme., (Vitamin M), Essential for decarboxylation of amino, Vitamin B6 or, acids, metabolism of tryptophans and fatty, Pyridoxine, acids., Pantothenic acid Essential for anabolism in form of, coenzyme A, skin growth., (B5), Essential for growth and carbohydrate, Biotin, B7, metabolism., (Vitamin H), Essential for formation of erythrocytes,, Vitamin B12, or Cyanocobalamine maintains nervous activities., or Cobalamine, Vitamin C or, Ascorbic acid, , Deficiency, , Xerophthalmia (dry cornea), nyctalopia, (night blindness, means no vision in dim, light), dermatosis (dry scaly skin),, keratomalacia., Osteomalacia in adults (weak bones, pelvis, get bent and deformed), rickets in children, (bent long bones and painful swelling on, wrist, elbows etc.)., Antioxidative, essential for reproductive Muscular atrophy, sterility in fowls and, metabolism, muscular growth., rats., Haemorrhage due to defective blood, coagulation., Beriberi, polyneuritis, gastrointestinal, disorders., , Cheilosis (cracking of skin at sides of mouth),, ariboflavinosis (blurred vision, cataract, eye, sores), loss of hairs, tongue sores., Pellagra (characterised by dermatitis,, diarrhoea, dementia and death), polyneuritis, (mental disorders), gastrointestinal, disorders etc., Megaloblastic anaemia (low Hb count),, nutritional disorders, retarded growth, Dermatitis, anaemia, mental disorders,, nausea., Dermatitis, nervous disorders, retarded, growth, burning feet syndrome., Skin lesions, loss of appetite, weakness etc., , Pernicious anaemia (due to production of, haemoglobin free immature RBCs as a result, of, deficient, intrinsic, factor),, hyperglycaemia., Formation of erythrocytes, help in integrity Scurvy (characterised by wound healing and, of capillaries, heart, muscles, bones, teeth, growth retardation), anaemia, malformation, gums etc., of teeth, bones and gums, reduces, coagulations time of blood.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 367, , ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ, , Table : Important minerals required in animal bodies., Mineral elements, , Significance, , Effects of deficiency, , MACRO ELEMENTS, , Calcium (Ca), , Required for formation of teeth and bones,, blood clotting, functions of nerves and muscles, , Weak teeth and bones; retarded body, growth., , Phosphorsu (P), , Required for formation of teeth and bones and, acidbase balance; component of ATP, DNA,, RNA, , Weak teeth and bones; retarded body, growth and physiology., , Sulphur (S), , Component of many amino acids, , Disturbed protein metabolism., , Potassium (K), , Required for acidbase balance, water, regulation and function of nerves., , Low blood pressure, weak muscles; risk, of paralysis., , Chlorine (Cl), , Required for acidbase balance; component of, gastric juice, , Loss of appetite; muscle cramps., , Sodium (Na), , Required for acidbase and water balances and, nervous functions, , Low blood pressure, loss of appetite;, muscle cramps., , Magnesium (Mg), , Cofactor of many enzymes of glycolysis and, a number of other metabolic reactions, dependent upon ATP, , Irregularities of metabolism, principally, affecting nervous functions., , Iron (Fe), , Component of haemoglobin and cytochromes, , Anaemia, weakness and weak immunity., , Iodine (I), , Important component of thyroxine hormone, , Goitre, cretinism., , MICRO ELEMENTS, , Flourine (F), , Maintenance of bones and teeth, , Weak teeth, larger amount causes, mottling of teeth., , Zinc (Zn), , Cofactor of digestive and many other enzymes, , Retarded growth, anaemia, rough skin,, weak immunity and fertility., , Copper (Cu), , Cofactor of cytochrome oxidase enzyme., Necessary for iron metabolism and, development of blood vessels and connective, tissues, , Anaemia, weak blood vessels and, connective tissues., , Manganese (Mn), , Cofactor of some enzymes of urea synthesis, and transfer of phosphate group, , Irregular growth of bones, cartilages and, connective tissues., , Cobalt (Co), , Important component of vitamin B12, , Anaemia., , Selenium (Se), , Cofactor of many enzymes; assists vitamin E, , Muscular pain; weakness of cardiac, muscles., , Chromium (Cr), , Important for catabolic metabolism, , Irregularities of catabolic metabolism and, ATP production., , Molybdenum, (Mo), , Cofactor of some enzymes, , Irregular excretion of nitrogenous waste, products.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 368, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , subcutaneous fat disappear, thin limbs, indigestion,, diarrhoea etc., Marasmus is due to deficiency of protein and, calories. It occurs in children between 6 months, and 3 years of age and kwashiorkar is common, in infants under 1 years of age whose diets are, deficient of proteins., Over nutrition means excessive intake of particular, nutrient which produces adverse symptoms. Eg., obesity and hypercholesterolemia., Obesity occurs due to greater intake of food calories, than the requirement of body. It is more common, in persons having higher intake of sweets,, carbohydrates rich food, fried articles, fat rich food, and absence of roughage of food., Obesity is characterised by large accumulation of, fat in tissues, bulky; overweight body which leads, to high blood pressure and heart problems and, which are prone to diabetes, hypertension and other, disorders., Hypercholesterolemia occurs due to excessive, intake of saturated fats like butter, ghee, vegetable, oil, red meat and egg and reduced biotin intake., Symptoms of hypercholesterolemia are, tremendously increased blood cholesterol level,, stiffening of blood vessels due to cholesterol, deposition, high blood pressure and various cardiac, disorders., , DIGESTIVE SYSTEM, l, , l, , l, , l, , l, l, , l, , Digestive system comprises alimentary canal and, accessory digestive glands which play an important, role in digestion., Alimentary canal is a long coiled tube having, muscular wall and glandular epithelium extending, from mouth to anus., Alimentary canal is divided into 4 main parts:, buccopharyngeal cavity, oesophagus, stomach, and intestine., Buccopharyngeal cavity (the space between the, jaws) is divided into three parts : vestibule, buccal, cavity and pharynx., Vestibule is the space between gums and lips., Buccal cavity is the space bounded dorsally by, palate, ventrally by throat (with tongue) and laterally, by alveolar processes of jaws having teeth., Palate forms the roof of the buccal cavity and, separates buccal cavity from nasal chamber., , l, l, , l, l, l, , l, l, l, l, l, l, l, l, l, l, l, l, l, , l, l, , l, , l, , Palate is differentiated into hard and soft palate., Hard palate is supported by bony processes and, having palatal rugae to grip the food during, mastication., Soft palate takes part in swallowing., Uvula, a hanging flap closes the internal nares during, swallowing of food bolus., Tongue is a thick muscular protrusible structure,, attached to the floor of buccal cavity by means of, soft ligamentous fold called frenulum., Tongue helps in ingestion, chewing and swallowing, of food., Four types of lingual papillae are– filliform,, fungiform, foliate and circumvallate., Filliform (without taste buds) located near centre, and most of the upper surface of the tongue., Fungiform contains few (810) taste buds., Foliate (absent in man) is found in rabbit and other, mammal., Circumvallate contains approximately 200 taste, buds., A number of tubular mucous glands are present over, the tongue. They are called Weber’s gland., The basal region of tongue contains two tonsils or, lingual tonsils., Tonsils contain lymphoid tissue., Tonsillitis is inflammation of tonsils., Teeth are hard structures meant for tearing, cutting,, crushing and holding food., Tooth is mainly made of ivory like substance called, dentine., In root region dentine is covered by bonelike cement, and peridontal membrane and in crown part,, dentine is covered by enamel (hardest, white,, shining)., Internally tooth has a pulp cavity with connective, tissue, nerve fibres, lymph and blood vessels., On the outside it contains odontoblast (dentine, producing) with protoplasmic outgrowth present in, canaliculi of dentine. A narrow pulp canal is present, at the base., Human teeth are thecodont (teeth embedded in the, alveoli), heterodont (presence of different types of, teeth), bunodont and diphyodont (appearence of, two sets of teeth in the life span)., Milk, deciduous or temporary teethbegin to appear, at the age of 6 11 months. They are completed by, the age of two years. There are 20 milk teeth.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ–, l, , l, l, , l, , l, , l, l, , Permanent teeth begin to appear between the age, of 6 12 years. Milk teeth are lost. Last molars, come out late after 18 years of age. They are called, wisdom teeth., Teeth are ectomesodermal in origin., Permanent teeth of man are of four types – incisors (8),, canines (4), premolars (8) and molars (12)., Dental formula for permanent teeth is–, 2 1, 2 3 2 + 1 + 2 + 3 2 16, i c pm m or, ´ = or32., 2 1, 2 3 2 + 1 + 2 + 3 2 16, Dental formula is the number of teeth in one half, of upper jaw divided by teeth of one half of the, lower jaw., Caries is decay of teeth due to degeneration of, enamel and formation of cavities., Pyrrhoea is infected gums and tooth sockets., Types of teeth, – Acrodont teeth is a part of bone, not, embedded in sockets, e.g., reptiles (except, crocodiles), amphibians., – Thecodont teeth is embedded in sockets,, e.g., mammals, crocodiles., – Monophyodont means one set of teeth, e.g.,, Platypus, toothed whale., – Diphyodont means two set of teeth milk, teeth (temporary) and permanent, e.g., mammals., – In polyphyodont condition, teeth can be, replaced many times, e.g. frog., – In isodont or homodont condition, all teeth, are similar, e.g., toothed whale., – Heterodont (more than one type): Four type, of teeth occur in humans incisors (cutting),, canines (tearing), premolars (grinding) and, molars (grinding, not present in milk, dentition)., – Pleurodont types of teeth is fixed by sides, to lateral surface of jaw ridge, e.g., reptiles., – Bunodont teeth have low cusps, e.g., humans., – Lophodont type of teeth have transverse, ridges, e.g., elephant., – Solenodont type of teeth have crescent, shaped cusps, e.g., sheep., – Secodont type of teeth have pointed cusps,, eg. carnivores., , l, , l, , l, l, , l, , l, l, l, l, l, l, l, , l, l, l, l, , l, l, l, l, , l, , 369, , Diastema, characteristics of ruminants, is a gap, between incisor and premolar due to absence of, canines on account of herbivorous diet., Pharynx is a posterior most part of buccopharyngeal, cavity lies between soft palate and 6th cervical, vertebra., Pharynx is distinguishable into three parts :, nasopharynx, oropharynx and laryngopharynx., Nasopharynx lies behind the nasal chamber and, has internal nares, eustachian canal and pharyngeal, tonsils., Oropharynx (lined by non–keratinized stratified, squamous epithelium) lies behind buccal cavity and, is the passage for food bolus., Laryngopharynx, lowest part of pharynx, has two, apertures : glottis and gullets., Glottis, lead into trachea, guarded by cartilaginous, flap, epiglottis which is made up of elastic cartilage., Gullets lead into oesophagus or food pipe. It is, normally closed., Tonsil occurs both in oropharynx and, laryngopharynx., Oesophagous is a long narrow, muscular tubular, structure which connects pharynx with stomach., It conducts the food to stomach by peristalsis., Stomach is widest and distensible Jshaped part of, alimentary canal, placed obliquely behind the, diaphragm., It is differentiated into three parts : cardiac, fundic, and pyloric., Cardiac stomach receives the oesophagus through, cardiac aperture, guarded by a cardiac sphincter., Cardiac sphincter prevents regurgitation of food., Gastric rugae, the longitudinal fold of the inner, mucosa of empty stomach increases the surface, area of digestion., Fundic is the main stomach because it produces, gastric juices including HCl., Pyloric part or pylorus (narrow part) is, differentiated into antrum, canal and sphincter., Pyloric sphincter regulates passage of food into, intestine., The regulation of food from stomach is more, common in infants due to their less developed, cardiac sphincter., Stomach helps in mechanical churning and, chemical digestion of food. It also acts as food, reservoir.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 370, , –, , –, –, –, –, –, l, l, , l, l, , l, , l, l, , l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Stomach of ruminants, Stomach of ruminants are differentiated into, four chambers : large rumen (paunch),, reticulum (honey comb), omasum, (psalterium) and abomasum (rennet)., Rumen, reticulum and omasum are, modified parts of oesophagus and secrete, no digestive juice., Rumen is used for churning, breaking of, food, fermentation of cellulose by, symbiotic microorganisms., Omasum is located to the right of rumen, and used for mechanical churning and, breaking of food and absorption of fluids., Reticulum is the smallest part which helps, in cellulose digestion., Abomasum is the glandular part which, function as true stomach., , Intestine is divided into large and small intestine., Small intestine is divided into three parts proximal, duodenum (shortest and wider part), middle, jejunum (thicker and vascular) and distal ileum, (thinner than jejunum and less vascular)., Small intestine is the longest part of alimentary, canal., Small intestine has circular folds called plicae, circulares and villi (contain lacteals) which, increases absorptive surface area., Lacteals are minute blind ended lymph vessel, where digested fats are absorbed and transported, to the bloodstreams through the thoracic duct., Cells lining the villi have brush border or microvilli., Peyer’s patches are lymphoid aggregate present in, the submucosa of ileum and involved in production, of Blymphocytes and protect the intestine from, infection., Small intestine is the main region where digestion, and absorption of food occur., Sphincter of Oddi guards the opening of common, bile and pancreatic duct into the duodenum., Ampulla of Vater is the region of duodenum where, common bile duct and pancreatic duct opens jointly., The semidigested acidified food that enters the, duodenum is called chyme., The distal end of the ileum is dilated into a small, bulb like structure called sacculus roduntus., , l, l, l, l, , l, l, l, l, l, l, l, l, , l, l, l, l, , l, l, l, l, l, l, l, , Large intestine is formed by three parts : caecum,, colon and rectum., Caecum in human is a pouch like small junction, between ileum and colon., An ileocaecal valve is present in the caecum., Externally caecum bears a blind tube, having, lymphoid tissue called vermiform appendix, (7 to 9 cm long and 1 cm diameter)., Infection of the vermiform appendix is called, appendicitis., Rupture of appendix is called peritonitis., Caecum and vermiform appendix are vestigial, in function., Vermiform appendix is functional in ruminants, and caecum is prominent in herbivorous animals., Colon is the largest part which has four segments:, ascending, transverse, descending and sigmoid., Colon has longitudinal bands called taeniae coli, and small pouches named haustra., Colon is concerned with conservation of water,, sodium or other minerals and formation of faeces., Rectum leads into anal canal which opens out by, anus present at base of trunk and guarded by anal, sphincter muscle., Enlargements of rectal veins causes severe painful, condition called piles or haemorrhoids., The chief function of large intestine is the, absorption of water and elimination of solid waste., Digestive glands are those glands which secrete, digestive juices for the digestion of food., Digestive juices contain digestive enzymes which, are divided into following categories on the basis of, their substrate: amylolytic or carbohydrase;, proteolytic; lipolytic and nucleolytic., Digestive glands includes salivary gland; gastric, gland; liver; pancreas and intestinal gland., Salivary glands are of three types – parotid,, submaxillary and sublingual., Parotid or Stenson’s duct open in vestibuli just, outside the second upper molars., Submaxillary or Wharton’s duct opens near the, lower central incisor., Sublingual or Rivinian ducts open under the tongue., Mumps is a viral infection (Myxovirus) of parotid, glands., In man, infraorbital gland (present in rabbit beneath, the eye) is absent.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ–, , Table : Types of digestive juices, , l, , Digestive juices, , Digestive gland, (Secreted by), , Secreted into, , Saliva, Gastric juice, Bile, Pancreatic, juice, Intestinal, juice (also, called succus, entericus), , Salivary glands, Gastric gland, Liver, , Mouth, Stomach, Duodenum, , l, , Pancreas, , Duodenum, , l, , Intestinal gland, , Small intestine, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, l, l, , l, , Saliva is a complex mixture and a hypotonic, solution that is secreted continuously from the, salivary glands under the control of ANS., Daily secretion of saliva is about 1 to 1.5 litres, and operates at 6.7 pH (slightly acidic, almost, neutral)., Secretion of saliva is a reflex action., Saliva is formed of about 95.5% water, 0.2%, minerals and 0.3% organic compounds like mucin, and a starch splitting enzyme ptyalin (salivary, amylase)., Mucin is a glycoprotein and it helps in lubricating, the food in its passage down by giving it a slimy, consistency., Mucin is mainly produced by the sublingual and, submaxillary gland whereas enzyme is mainly, from parotids., Lipase is secreted by the Ebner’s glands on the, dorsal surface of tongue. It is also called lingual, lipase which is active even at the acidic pH of, stomach., Gastric glands are numerous simple, branched or, unbranched tubular gland which are formed by, infolding of the epithelium., Three types of gastric glands are – cardiac gland, (secrete alkaline mucus); pyloric gland (secrete, alkaline mucus) and fundic gland., Fundic gland possess four types of enzyme, secreting cells: chief or peptic (zymogen) cells,, oxyntic cells, goblet cells and argentaffin cells., Secretion of gastric glands is called gastric juices., Daily secretion of gastric juices is 23 lt., Secretion of gastric juice is under nervous as well, as hormonal control., , l, , l, , l, , l, , l, , 371, , Gastrin stimulates gastric gland of stomach to, secrete large amount of gastric juices. It relaxes, pyloric sphincter and closes cardiac sphincter., Intestinal glands, formed by surface epithelium of, small intestine, occurs as Crypts of Lieberkuhn, and Brunner’s gland., Brunner’s glands mostly occur in duodenum and, opens into crypts of Lieberkuhn., The secretion of both glands are collectively called, intestinal juice or succus entericus., Intestinal juice is slightly alkaline (pH 7.5) and, contains mucus, inorganic salts, and many enzymes, like enterokinase, intestinal lipase, maltase, sucrase,, nucleopeptidase, isomaltase etc., Enterocrinin, an intestinal hormone produced by, duodenum and jejunum, stimulates secretion of, intestinal juice., Crypts have different types of enzyme secreting cells:, paneth cell for lysozyme and argentaffin cells for, hormones., Argentaffin cells (or enterochromaffin cells), produce secretin and peristaltic stimulant called 5, hydroxytryptamine (serotonin)., Liver is the largest and multilobulated gland of, about 1.5 kg weight and nearly 1/40 of total body, weight., Liver is differentiated into small left lobe and large, right lobe separated by falciform ligament., In rabbit, liver is made up of 5 lobes: Ist lobe, (caudate); IInd lobe (right central, largest); IIIrd, lobe (left central); IVth lobe (left lateral) and Vth, lobe (spigelian, smallest)., In frog, liver is trilobed and liver of man is, bilobed., , l, , l, , l, l, l, , Glisson's capsule, characteristic of liver, is a thin, layer of dense connective tissue which surrounds, the liver lobule enclosing branches of portal vein,, the hepatic artery, the bile duct and lymphatic capsule., Kupffer cells of liver sinusoids acts as phagocytes, which eat up the dead cells and bacteria by, phagocytosis., Gall bladder is a pear shaped yellow green sac like, structure lies on the inferior surface of the right lobe., Gall bladder stores bile, which is secreted by liver, cells and collected by bile capillaries., Bile produced by liver makes the media alkaline, having pH 7.8 8.6.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 372, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Hormonal control of digestive secretion., , Hormone, 1. Gastrin, , Secreted by, , Pyloric epithelium on entry, of food (bolus), 2. Enterogastrone Duodenal epithelium on, entry of acid chyme, 3. Cholecystokinin Duodenal epithelium on, (CCK), entry of acid chyme, 4. Secretin, Duodenal epithelium on, entry of acid chyme, 5. Duocrinin, Duodenal epithelium on, entry of acid chyme, 6. Entrocrinin, Duodenal epithelium on, entry of acid chyme, 7. Pancreozymin, Duodenal mucosa, l, , l, , l, l, l, , l, , l, l, , l, , l, l, , Action, Stimulates the release of gastric juice and churning, movements of stomach, Stop secretion of gastric juice, Causes release of bile from gall bladder, also brings about, the release of enzymes in the pancreatic juice., Cause release of sodium bicarbonates in the pancreatic, juice, also stimulates production of bile by liver., Causes release of mucus from Brunner’s gland into intestinal, juice., It brings about release of enzymes from the crypts of, Leiberkuhn into intestinal juice., Stimulate secretion of pancreatic enzyme., , Bile contains 92% water; 6% bile salts; 0.3% bile, pigments [bilirubin (yellow); biliverdin (green)], 0.3% to 1.2% fatty acids; 0.30.9% cholesterol, and 0.3% lecithin. Lecithin compound decreases, surface tension and helps in fat emulsification., Bile salts contain NaCl, sodium bicarbonate (both, inorganic) and sodium glycholate and sodium, taurocholate (both organic)., Medicines contain bile salts used for dissolving gall, stones., Bile capillaries unite to form hepatic duct., Bile duct also known as choledocus duct, is formed, by joining of cystic duct (arise from gall bladder), and common hepatic duct from different liver lobes., In man, bile duct first opens into Ampulla of vater, and the latter is surrounded by sphincter of Oddi, muscle., The process of bile secretion is called choleresis., Presence of stones in gall bladder and bile duct is, called cholelithiasis and cholecystolithiasis, respectively., Gall stones are formed by bile salts and calcium,, whose formation is promoted by high cholesterol, level., Surgical removal of gall bladder is called, cholecystectomy. It is commonly done by laproscopy., In human, removal of gall bladder disturbs fat, digestion leading to steatorrhea (loss of increase, amount of fat in faeces)., , l, , l, l, , l, , l, l, l, l, l, , l, l, , l, , Liver produces an anticoagulant heter, opolysaccharide called heparin which prevents, blood clotting inside the blood vessel., Liver produces two proteins prothrombin and, fibrinogen which helps in clot formation., Liver act as haemolytic organ. It also acts as an, erythropoietic organ in the embryo. In adults this, function is taken over by bone marrow., Sphincter of Boyden is a strong sphincter of smooth, muscle surrounding the bile duct before its joining, with pancreatic duct., Liver cirrhosis is loss of liver architecture which is, replaced by fibrous and fatty tissue., Hepatitis is inflammation or infection of liver., Jaundice is raised bilirubin in blood and its, deposition in various body parts., Pancreas is a compound elongated organ situated, in the limbs of the U shaped duodenum., Pancreas contain two different kinds of glandular, tissue an exocrine part (secretes pancreatic juice), and an endocrine part (secretes hormonesinsulin, and glucagon)., Pancreatic secretion (pancreatic juice) is stimulated, by cholecystokinin and secretin both., Complete digestive juice is pancreatic juice as it, possesses amylolytic, lipolytic and proteolytic, enzymes., Pancreatic juice is colourless watery fluid, slightly
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ, , l, l, , alkaline (pH 7.5–8) due to presence of sodium, bicarbonate., Among the mammals, because of the rennin only, man can digest the lactose found in the milk., Duct of Wirsung is main pancreatic duct. Accessory, duct is called the duct of Santorini, which may take, pancreatic juice directly into the duodenum., Hepatopancreas is digestive gland found in many, invertebrates (e.g. prawn) which performs the, functions of both liver and pancreas., , l, , Coprophagy means feeding on own faeces. It is, found in rabbit., , DIGESTION AND ABSORPTION, l, , l, , l, , l, , l, l, l, l, , l, l, , l, , l, , Digestion is the process of breaking down of complex, and insoluble organic substances (carbohydrates, fats,, proteins) into simpler and soluble substances, like glucose, amino acids and fatty acids so that, they can easily be absorbed into the body., Digestion is the process by which food substances, are broken down by mechanical and chemical, means., Mechanical digestion comprises mastication or, chewing, liquefaction of food by digestive juices,, swallowing and peristalsis., Major utility of breaking up of food into small bits, during chewing is to increase the surface area of, food. It helps the enzymatic action., Chemical digestion includes the enzymatic action, on food., In hydrolysis of nutrients, a small amount of, energy is released as heat., Four main types of digestive enzymes are :, carbohydrases, proteinases, lipases and nucleases., Carbohydrase includes amylase (polysaccharides, to disaccharides) and disaccharidases (maltase,, sucrase and lactase)., Proteinases can be endopeptidase and, exopeptidase., Endopeptidase cleaves a polypeptide chain at, specific sites between aminoacids, eg., chymotrypsin., Exopeptidase cleaves amino acids from the ends, of a polypeptides chain. Eg. carboxypeptidase which, break down protein in the small intestine., Lipase (steapsin) acts on ester bonds of fats on, triglycerides., , l, , l, l, l, , l, , l, l, l, l, l, , l, l, , l, l, l, l, , l, , l, l, l, , 373, , Nuclease hydrolyses nucleic acid into nucleotides, and finally into nitrogenous bases, pentose sugar, and phosphate group, e.g., DNAase and RNAase., Digestion starts from the mouth where masticated, food is mixed with saliva., Tongue rolls up the masticated moistened food into, small ball called bolus., Contraction of pharynx pushes the bolus into, oesophagus. The phenomenon is known as, swallowing or deglutition., Peristalsis is a series of waves of contraction that, pass from one end to the other and is meant for, pushing food., Vomiting is reverse peristalsis (also called amstalsis), for ejection of harmful substances from gut., Regurgitation is the back flow of food from, stomach to oesophagus. It is found in ruminants., Peristalsis occurs usually in oesophagus, stomach, and intestine. Least peristalsis occurs in rectum., Saliva has no proteolytic enzyme so no digestion, of protein takes place in buccal cavity., Ptyalin or salivary amylase (present in saliva), converts starch and glycogen into limit dextrins,, maltose and isomaltose., Salivary amylase functions at or near neutral pH, in humans and pig. It is absent in herbivores., Saliva contains an antibacterial enzyme, (lysozyme) which dissolves the cell wall of gram, positive bacteria and kills them., There is no digestion in oesophagus. Oesophagus, conducts the food from mouth into stomach., Stomach is the chiet site of protein digestion., Food mixed with gastric juice in the stomach is, called chyme., Chyme is thick liquid made of partially digested, food and stomach juices; made in the stomach and, moves into the small intestine for further digestion., Enzyme secreting cells of fundic gland are – chief, cells (zymogenic or peptic or serous cells),, parietal cells, globlet cells and argentaffin cells., Besides pepsinogen, peptic cells also secrete, prorennin and a weak enzyme gastric lipase., Pepsinogen is activated into pepsin by HCl., Rennin (also called rennet or chymosin), changes, milk soluble protein caesin into insoluble semifluid, calcium paracaesinate. This is called curdling of, milk.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 374, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Digestion in humans, Digestive glands, and juice, , Enzyme, , Optimum pH, , Substance acted, upon, , End products, , Controlling factor, , Salivary glands Salivary amylase Neutral, 7.00, or ptyalin, (Saliva), 6.76.8, , Starch, , Maltose, , Gastric glands, , 1. Pepsin, , Acidic, , Proteins, , Peptones, peptides, , (Gastric juice), , 2. Rennin, , 1.5 to 2.00, , 3. Lipase, , 1.5 to 2, , Caeseinogen of, milk, Fat, , Paracaesein and, casein, Fatty acid and, glycerol, , hormones from, mucosa of stomach, , Liver (Bile juice) No, digestive Alkaline, 7.1 to 8.3, enzyme, , Fat, , Emulsified fat:, chylomicrons, , Secretin &, cholecystokinin, hormones from, intestinal mucosa., , Pancreas, 1. Trypsin, (Pancreatic juice) 2. Chymotryspin, , Proteins, Proteins & pep, tides, Polypeptides &, Peptones, Starch, Fat, , Peptides, Amino acids, , Secretin and, Pancreozymin, hormones secreted, from mucosa of, small intestine, , Amino acids, Fatty acids &, Glycerol, Glucose &, fructose, Glucose, , 7.58.0, 7.58, , 3. Carboxypepti 7.58, dase, 4. Amylase, 7.58, 5. Lipase, 7.58, Intestinal glands 1. Erepsin, (Intestinal juice 2. Lipase, or, Succus, entericus), 3. Sucrase, , 7.6, 7.6, , Polypeptides, Fats, , 7.6, , 4. Maltase, , 7.6, , 5. Lactase, , 7.6, , Sucrose (Cane, sugar), Maltose (Malt, sugar), Lactose (milk, sugar), , l, l, l, , l, , Amount of rennin decreases with age, so absent, in adult man., Gastric lipase is active in infants which changes, milk fat tributyrin into fatty acids as glycerols., HCl secreted from oxyntic cells makes the gastric, juice acidic (pH 2.0 3.7), which is essential for, conversion of pepsinogen (inactive) to pepsin, (active)., Pepsin is a protein splitting endopeptidase., Pepsin, Protein ¾¾¾¾, pH 1 3.5® Proteoses + Peptones, , l, , The most important functions of HCl is to activate, both pepsinogen and prorennin and killing of micro, , l, l, , l, , l, , Nervous reflex, and adrenaline, hormone, and, , Amino acids, Maltose, Fatty acid and, glycerol, , Nervous reflexes, and gastrin, , Secretin hormone, from mucosa of, small intestine, , Glucose &, Galactose, , organisms like bacteria ingested with food and, drinks., The total achlorohydria means lack of HCl, secreted in stomach., Mucus secreted by goblet cell protects stomach, wall against HCl action and protein digesting, enzymes., The gastric juices do not contain carbohydrolase, (carbohydrate splitting enzyme), so there is no, digestion of carbohydrate in stomach., Intrinsic factor (or Castle’s intrinsic factor) is, secreted from oxyntic cells of stomach, which, helps in vitamin B12 absorption.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░śŚŕĽŚĽŐň– ·– ▼ĽĹĚřŚĽŢĚ– ☼ťřŚĚŇ–, l, l, , l, l, l, , l, l, , l, l, , l, , l, l, , l, l, l, l, , l, l, l, , l, , Serotonin secreted by argentaffin cells is a smooth, muscle stimulant., Gastrin secreted by gastric G cells stimulates HCl, production., Food in the small intestine is in the form of liquid, emulsion called chyle., Chyle is mixed with three digestive fluids namely, bile, pancreatic juice and intestinal juice., Bile contains no digestive enzymes, yet play an, important role in fat digestion and absorption., Bile helps in release of enterokinase enzyme., Liver regulates the blood sugar level either by, glycogenesis or by glycogenolysis and also control, lipogenesis., The liver stores food in the form of glycogen., The presence of bile in the small intestine is also, necessary for the absorption of the fat soluble, vitamins A, D, E and K., Emulsification is the breaking of large fat droplets, into a fine emulsion by bile juice (bile salts) of, the liver., The bile salts emulsify the fat for proper lipase, activity., Pancreatic juice is alkaline (7.5 8.5 pH),, colourless liquid having four types of enzyme :, proteolytic, proenzyme, (trypsinogen,, chymotrypsinogen and procarboxypeptidase);, nucleases (DNAase and RNAase); steapsin or, pancreatic lipase and pancreatic amylase., Pancreatic juice takes part in the digestion of, proteins, carbohydrates and fats., Steapsin (pancreatic lipase) is the principal fat, digesting enzyme., Steapsin converts fats into fatty acids,, monoglycerides and glycerol., Pancreatic amylase hydrolysis starch, glycogen,, and dextrin into limit dextrin, maltose and, isomaltose., Nucleases hydrolyse nucleic acid into nucleotides., Trypsin acts in alkaline medium (pH 7 to 9), in, which most proteins are negatively charged., Trypsin changes chymotrypsinogen to, chymotrypsin and procarboxypeptidase to, carboxypeptidase., Chymotrypsin changes caesin of milk into, paracaesin., , l, l, l, l, , l, , l, , l, l, , l, , l, l, l, l, l, l, , l, l, l, l, , 375, , Trypsin changes peptones and proteins into, peptides., Carboxypeptidase changes larger peptide into, smaller peptides and amino acids., Pancreatic juice has two more lipolytic enzyme , phospholipase and cholesterolesterase., Secretin and pancreozymin hormones are secreted, from mucosa of small intestine and regulates, pancreatic activities., The secretion of both the Brunner’s glands (occur, mostly in duodenum) and crypts of Leiberkuhn, are collectively known as intestinal juice (or succus, entericus)., The important enzymes in intestinal juice or, succus entericus are – enterokinase, erepsin,, disaccharidases, intestinal lipase, polynucleotidase, and nucleosidase., Enterogastrone produced in duodenum inhibits, the secretion of HCl., Erepsin includes both aminopeptidase and, carboxypeptidase, it hydrolyses all small peptides, and dipeptides of chyme into aminoacids., Secretin and cholecystokinin hormones are, released from certain cells of intestinal mucosa, under the influence of HCl, fat and products of, protein breakdown in the chyme., Germs entering the stomach along with food are, killed in alimentary canal where pH is 3., The chief function of large intestine is the, absorption of water and elimination of solid wastes., Protein digestion occurs in stomach, duodenum,, jejunum and ileum. It is completed in ileum., Digestion of all major nutrients of food is, completed in small intestine., Absorption of digested food mainly occurs in, ileum of small intestine., Absorption is a process by which nutrients are, circulated throughout the body by blood and lymph, and supplied to all body cells according to their, requirements., Absorption occurs through simple diffusion,, facilitated diffusion and active transport., Maximum absorption takes place in ileum., Fatty acids and glycerol are absorbed by lacteals, in villi. They are taken in lymph vessels., Amino acids and glucose are carried by hepatic, portal vein.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 376, , l, , l, l, , l, l, , l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Some nutrients such as fructose and mannose are, absorbed from intestine by facilitated diffusion. The, process is more rapid than simple diffusion., Water is absorbed by osmosis from the intestinal, lumen to intestinal cells., With the accumulation of faceal matter, colon, develops a strong peristaltic movement, which, produce the urge for defaecation., Defaecation or egestion is the elimination of, undigested food through the anus., Appetite (feeding) centres and satiety centres, (stopping of ingestion) are located in, hypothalamus., Anorexia is loss of appetite., Vomiting centres are located in medulla, oblongata., Diarrhoea is watery stool, or increased frequency,, or both, when compared to a normal amount., Diarrhoea may be acute (shortterm), which is, usually related to bacterial or viral infections, or, chronic (longterm), which is usually related to a, functional disorder or intestinal disease., Symptoms of diarrhoea may include: cramping, abdominal pain, bloating, nausea, urgent need to, use the restroom, fever bloody stools etc., Hepatitis is the inflammation of the liver, resulting, , l, , l, l, l, l, l, , l, , l, , in liver cell damage and destruction., Lactose intolerance is a condition caused by a, lack of an enzyme called lactase, which, in turn,, causes the body to be unable to digest lactose, a, sugar found in milk products., Symptoms of lactose intolerance are nausea,, cramps, bloating, gas, diarrhoea., Alactasia is inherited condition causing the lack, of the enzyme needed to digest milk sugar., Constipation is a condition in which the stool, becomes hard and dry., Continence is the ability to hold in a bowel, movement or urine., Crohn’s disease is a chronic form of inflammatory, bowel disease that usually affects the lower small, intestine (called the ileum) or the colon, but it, can affect the entire gastrointestinal tract. It is, also called regional enteritis and ileitis., Heartburn is a painful, burning feeling in the chest, caused by stomach acid flowing back into the, oesophagus., Peptic ulcer is sore in the lining of the oesophagus,, stomach, or duodenum; usually caused by the, bacterium Helicobacter pylori. An ulcer in the, stomach is a gastric ulcer; an ulcer in the duodenum, is a duodenal ulcer.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 377, , ▲ŕĚďŚĺĽňĹ– ·– ◄ŤĘĺďňĹĚ– Őě– ◙ďřĚř–, , Chapter 39, , Breathing & Exchange, of Gases, l, , l, , l, , l, l, , l, , l, l, , l, , Respiration is the catabolic process which involve, exchanges of environmental oxygen and body’s, carbon dioxide through liquid medium to utilize, the oxygen for the oxidation of glucose in the, mitochondria to produce the energy., Respiration may be aerobic (which involves intake, of oxygen and liberation of carbon dioxide) and, anaerobic (which does not use oxygen in the, breakdown of respiratory substrata), also called, fermentation in microorganisms like yeast and, some bacteria., Anaerobic respiration is also occurs in intestinal, parasites (such as tapeworm, liver fluke etc) and, mammalian RBC’s and under O2 deficiency in, skeletal muscles., Erythrocytes perform only anaerobic respiration, as they do not have mitochondria., The respiration (aerobic) in higher animals is brought, about in 2 phases – external respiration (or, breathing or ventilation) in which intake of O2, from the surrounding medium and elimination of, CO2 into that medium; and internal respiration (or, tissue or cellular respiration) in which oxidation, of nutrients in the cells producing CO2 and energy., In direct respiration, gases are directly exchanged, between body cells and from the environment, without involving blood, e.g., insects, worms,, coelenterates., In indirect respiration, a respiratory surface is, present for exchange of gases., Respiration (involuntary process) is the combined, process of inspiration (breathing air into the lung), and expiration (expelling out of air from lung)., The respiratory system is composed of the nasal, passages, the olfactory epithelium, a conducting, , Table: Different types of respiration in, different animals, Types of respiration/, Respiratory organ, , Animals, , Protozoans, sponges,, coelenterates, Earthworm, leech, frog, Cutaneous respiration, Prawn, Unio, fish etc, Branchial respiration, Insects and myriapods, Tracheal respiration, Spider, Limulus, frog, Book lung, book gill,, b u c c o p h a r y n g e a l respectively, respiration, Body wall, gills (ctenidia) Mollusca, & pulmonary sac, Echinoderms, Tube feet, Reptiles, birds, mammals, Pulmonary respiration, Some turtles, Cloacal respiration, Lining of epithelium of Fishes, cloaca, gut etc., American, lung, fish, Pelvic gills, Lepidosiren, Fishes like Acipenser,, Opercular gills, Lepidosteus, Polypterus, Spiracle of elasmobranchs, Pseudobranchs, Amphipnous, Channa, Pharyngeal diverticula, Clarias & Anabas, Branchial diverticula, Lung fishes, Swim bladder, , • Cell surface respiration, •, •, •, •, •, •, •, •, •, •, •, •, •, •, •, , l, l, , airway which includes the nasopharynx, larynx, trachea, bronchi and bronchioles and the, respiratory portions of the lungs., Respiratory system is endodermal in origin., The basic functions of the respiratory system are –, –, To absorb oxygen from the atmosphere into, the blood for use in cellular respiration, –, To eliminate from the blood into the, atmosphere the carbon dioxide produced by, cellular respiration
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 378, , ŕďőĽę– ĐĽŐńŐĹť, , –, , l, , l, l, l, , To help maintain the normal pH (hydrogen, ion concentration) of the blood by adjusting, the concentration of carbon dioxide in the, blood., These three functions are regulated primarily by, regulating pulmonary ventilation, the total, volume of gas exchanged between the lungs and, the atmosphere., Pulmonary ventilation is regulated by adjusting, the rate and depth of breathing., The prime respiratory organ in vertebrates is lung., Mammalian lungs principally act as ‘suction pump’., Nasal cavities (containing ciliated and goblet cells), modify incoming air and moistened it before it, enters lung., Smoke paralyses the cilia and continued, smoking destroys the cilia/ciliated cells, which, are then replaced by goblet cells. This causes, the accumulation of excess mucus in the lungs, together with particles, tar and carcinogen., , l, l, l, , l, l, l, , l, , l, , l, , l, , Nasopharynx connects the nasal cavities to the, larynx and the rest of the respiratory system., Pharynx serves as a common passage for both air, and food., Larynx (or voice box) is composed of cartilages,, ligaments, muscles and a mucosal surface and, prevents indigested solids and liquids from, entering the respiratory system and also contains, the vocal cords which produce speech sounds., Larynx is called Adam’s apple in man., An inflammation of the larynx is called laryngitis., The pitch of sound is determined by the tension, on the vocal cords. The greater the tension, the, higher the pitch., Main cartilages of larynx are– thyroid cartilage, (most prominent, Cshaped), cricoid cartilage, (shape like a signet ring), arytenoid cartilage, (at the anterior of which cartilage of Santorini is, attached) and epiglottis (a leaf shaped cartilage)., Epiglotts is the structure (containing elastic, cartilage) that prevents the entry of food into, respiratory tract during swallowing., Trachea (or wind pipe) which carries air between, the larynx and the bronchi are supported by, incomplete rings of Cshaped cartilage (hyoid, bone) in its wall., Mucous gland present in ciliated epithelium of, , l, , l, , l, , l, , l, l, , l, l, l, l, , l, l, , l, , l, , l, l, , trachea protects the respiratory system for infections, by holding the bacteria and dust particles coming, in system with air., Trachea (lower part) branches into two bronchi,, one to each lung and these branch within lungs, into many smaller bronchioles., Bronchi (air passages) have a pseudostratified, ciliated columnar epithelium containing numerous, goblet cells, macrophages and fibroblast., Bronchioles are of three types large bronchioles, (having simple columnar epithelium of ciliated, cells), terminal bronchioles (most distal simple, bronchioles) and respiratory bronchioles (having, alveoli in their walls)., Bronchiolar (clara cells) cells are the characteristic, of the bronchioles., The chief difference between bronchi and large, bronchioles is that bronchioles lack cartilage., Mammalian lungs are paired, soft, pinkish and, highly elastic structure lying in the pleural cavities, of the thorax., The covering of the lung is called pleura., The outside of each lung is covered by a thin, membrane called the visceral pleural membrane., Parietal pleural membrane lines the inner wall of, the thoracic cavity., The space between two membranes (visceral and, parietal) is called pleural cavity which is normally, very small as the pleural membranes are in close, contact., A small space called mediastinum lies in between, the two lungs., The right lung is divided into three lobes and left, into two. Right lobes are superior, middle and, inferior; and left lobes are superior and inferior., The left lung is smaller than right and has a, concavity, the cardiac notch, where the heart lies., Mammalian lungs are composed of millions of, alveoli (made of simple squamous cells) that, provide a huge surface area for gas exchange., Number of alveoli in human pulmonary system is, 300 400 million with surface area of 100 sq.mt., Within the lungs each bronchus or bronchi, subdivides many times into smaller tubes called, respiratory bronchioles of lesser diameter without, cartilaginous ring.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ŕĚďŚĺĽňĹ– ·– ◄ŤĘĺďňĹĚ– Őě– ◙ďřĚř–, l, , l, , l, , l, , l, , l, , l, l, , Each respiratory bronchiole divides to form, alveolar ducts terminating into small dilated air, sacs or infundibulum., Walls of air sac form hollow air cells or alveoli, which are the ultimate unit of bronchial tree to, participate in gaseous exchange., Wall of alveoli is thin membrane and lined by 2, types of epithelial cells –, –, Type I cell Flat cells with large cytoplasmic, extension and are primary lining cell., –, Type II cell (granular pneumocyte) Thicker, and contains numerous lamellar inclusion, bodies. These cells secretes surfactant., Surfactant is a lipid surface tension lowering agent, which prevents alveoli from collapsing during, respiration., The ability to secrete surfactant doesn’t develop, untill around the eight or ninth month of pregnancy, so there frequently is a problem in premature babies, with the lack of surfactant causing the alveoli to, stick together when the body exhales., Dipalmatoyl lecithin, a predominant phospholipid, in multilamellar bodies, is an active component of, the pulmonary surfactant., Alveoli is surrounded by a network of capillaries, of the pulmonary artery and veins., Air enters into the lung in this way , , l, l, , l, , l, , l, , l, , l, , Inhaled air, Right and, Trachea, left bronchi, Bronchioles, l, , l, , l, l, , l, , Glottis, , l, , Larynx, , Mouth / Nose, or nasal chamber, , l, , Alveoli, , The diaphragm is a thin musculomembranous, dome shaped muscle that separates the thoracic, and abdominal cavities., The diaphragm is the main muscle of respiration, and its action is only partly under control of, will., The diaphragm is supplied with phrenic nerves., The contraction of diaphragm assists in, inspiration, micturition (passing of urine),, defaecation (the passing of faeces) and parturition, (childbirth)., Breathing is a physical process whereas, respiration is a biochemical event in which energy, is released in the form of ATP., , l, l, l, , l, , 379, , Breathing is periodically filling and emptying of lung., Rate of breathing is 40 60/ min in neonates,, 14 18 min in adolescents, 12 14/ min in human, adults and 18 22/ min in children., Inspiration is the active process as it is the result, of muscle contraction. It involves external, intercostal muscles and diaphragm., During inspiration, the diaphragm and the, intercostal muscles contract. The diaphragm moves, downwards increasing the volume of the thoracic, (chest) cavity, and the intercostal muscles pull the, ribs up expanding the rib cage and further increasing, this volume., This increase of volume lowers the air pressure, in the alveoli to below atmospheric pressure., Because air always flows from a region of high, pressure to a region of lower pressure, it rushes in, through the respiratory tract and into the alveoli., This is called negative pressure breathing,, changing the pressure inside the lungs relative to, the pressure of the outside atmosphere., Expiration is a passive process as it is the result, of relaxation of muscles. This returns the thoracic, cavity to its original volume, increasing the air, pressure in the lungs and forcing the air out., During forced breathing or heavy exercise an, active process is involved requiring internal, intercostal muscles., Inspiration is for about 2 secs and expiration for, 3 sec., Dead space encloses the air not involved in gaseous, exchange as it is enclosed in the respiratory passage, such as nasal chamber. It reduces the amount of, fresh air that enters the lungs., Cough is a forcible expiration usually proceeded, by a prolonged inspiration., Hiccough is a noisy inspiration caused by muscular, spasms of the diaphragm at regular intervals., Gaseous exchange take place by physical process, of diffusion (a process in which substance moves, from a higher to a lower concentration)., In order to provide sufficient oxygen and to get rid, of sufficient carbon dioxide there must be, –, A large surface area for gaseous exchange, –, A very short diffusion path between alveolar air, –, Blood concentration gradients for oxygen
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 380, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , and carbon dioxide between alveolar air and, blood., The gaseous exchange takes place between external, environment and blood through respiratory organs., The site of gaseous exchange in lungs is alveoli., The gaseous exchange is the diffusion of oxygen, from alveolar air into the blood and diffusion of, CO2 from blood to alveolar air., The percentage of oxygen in inhaled air is about, 21 and oxygen content of the air we expire is, about 16., Carbon dioxide amount in atmosphere is 0.04%,, carbon dioxide of the air we expire is about 3.6%., Water has poor solubility for O2 therefore blood, plasma is poor carrier. 98.5% of oxygen is, transported by blood with the help of the respiratory, pigment haemoglobin present in RBCs., In breathing, lungs are neither completely filled, with air nor completely emptied and this condition, is known as pulmonary volume., Tidal volume is the volume of air inspired and, expired involuntarily in each normal breath. It is, about 500 ml., Inspiratory reserve volume (IRV) is the volume, of air inspired over and above the tidal volume by, deepest voluntary inspiration. It is about 3000 ml., Expiratory reserve volume (ERV) is the amount, of air expired over and above the tidal volume by, forceful voluntary expiration. It is about 1100 ml., Residual volume (RV) is the volume of air that, remains in the lungs after the most forceful, expiration. It is about 1200 ml., Inspiratory capacity is the total amount of air a, person can inspire by maximum distension of his, lung. It is equal to total volume and inspiratory, reserve volume. It is about 3500 ml., Functional residual capacity (= RV + ERV) is the, amount of air that remains in lungs after normal, expiration. It is about 2300 ml., Vital capacity (= IRV + TV + ERV) is the maximum, amount of air which can be expelled forcefully, from lungs after first filling with a maximum deep, inspiration. It is about 4600 ml., Total lung capacity is the maximum amount of air, lungs can hold i.e., the total of TV, IRV, ERV and, RV of air. It is about 5800 ml., , l, , l, l, , Pulmonary volume and pulmonary capacity vary in, different persons according to size and build of, body., Pulmonary ventilation is the product of tidal, volume and respiratory rate., Oxygen is transported in the blood in two ways –, (i) by mixing with haemoglobin (97%) as, oxyhaemoglobin, and (ii) by dissolving in, plasma (3%)., Carbon monoxide poisoning, Haemoglobin has much more about 250 times, more affinity for carbon monoxide than for, oxygen. In the presence of carbon monoxide,, it readily combines to form a stable compound, called carbonmonoxyhaemoglobin (COHb). The, oxygen combining power decreases and as a, result tissues suffer from oxygen starvation. It, leads to asphyxiation and in extreme cases to, death. The person needs to be administered with, pure oxygencarbon dioxide mixture to have a, very high pO 2 level to dissociate carbon, monoxide from haemoglobin. Carbon monoxide, poisoning occurs often in closed rooms with, open stove burners or furnaces or in garages, having running automobile engines., , l, , l, , l, l, , l, l, l, , l, , Haemoglobin is a protein composed of four, polypeptide chains and four organic compounds called, heme groups which possess an atom of iron., Haemoglobin molecule is made of two achains, which has 141 amino acids and two bchains with, 146 amino acids each., Heme is the respiratory carrier part of the, haemoglobin molecule., Each heme unit contains a central iron atom which, is in the ferrous (Fe2+) state and it is this iron, atom that combines with oxygen., The chemical formula of oxyhaemoglobinis Hb (O2)4., The metal constituent of haemoglobin is iron., The relationship between oxyhaemoglobin, saturation and oxygen tension is called oxygen, haemoglobin dissociation curve., Each of the four Fe2+ ion in the haemoglobin, molecule can bind with one molecule of O 2., So oxyhaemoglobin carries 1 – 4 molecules of, oxygen.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 381, , ▲ŕĚďŚĺĽňĹ– ·– ◄ŤĘĺďňĹĚ– Őě– ◙ďřĚř–, l, , l, , l, , l, , l, , l, , Haemoglobin affinity for O2 is inversely related, to the P50 which is the O2 tension that produces a, 50% saturation of haemoglobin with O2., Bohr effect refers to the displacement of the, haemoglobin saturation curve and the, subsequent increase in P50 that is caused by an, increase in CO2 tension. In this O2 affinity of, haemoglobin decreases with the fall of blood pH., The oxygen carrying capacity of blood is 20 ml/, 100ml., CO2 carrying capacity of blood is 3.7ml / 100 ml, of blood., Carbon dioxide is transported in the blood in, three ways –, –, 7% dissolved in the plasma (as carbonic acid), –, 23% bound to haemoglobin (as, carbaminohaemoglobin), –, 70% as bicarbonate in the plasma following, an enzyme catalysed reaction in red blood, cell (commonest one)., Changes in carbon dioxide concentration are directly, related to changes in hydrogen ion concentration, (pH) by the carbonic acidbicarbonate buffer reaction:, CO2 + H2O, , (Carbonic, anhydrase), , Carbon dioxide + water, , l, , l, , l, , l, , l, , l, , H2CO3, , H + HCO, +, , Carbonic acid, , –, 3, , Hydrogen ion +, bicarbonate ion, , Since more carbon dioxide is eliminated during, hyperventilation, the hydrogen ion concentration, of the blood declines (pH increases and the blood, becomes more alkaline)., , l, , To maintain electrostatic neutrality of plasma many, chloride ions diffuses from plasma into RBC and, carbonates ions from RBC to plasma. The chloride, content of RBC increases when oxygenated blood, becomes deoxygenated is called chloride shift or, Hamburger shift., Haldane effect is the increased CO2 uptake, because of removal of O2 from haemoglobin. It, minimize the increase in CO2 tension that occurs, in the venous blood which inturn causes venous, blood to be less acidic than it would be otherwise., Haldane effect is a way of buffering the CO2, molecules which has the potential to form carbonic, acid after being hydrated., Bohr effect shifts the O2 Hb dissociation curve, to right and promotes oxygenation of, haemoglobin in lungs., Carboxyhaemoglobin (COHb), formed when, carbon monoxide combines with haemoglobin,, decreases the functional haemoglobin, concentration as a result of which tissues suffer, from oxygen starvation and leads to asphyxiation, (suffocation) and in extreme cases to death., Haemoglobin has much more about 250 times, affinity for CO than oxygen., Foetal haemoglobin has a greater affinity for O2, than adult haemoglobin as it binds 2,3 DPG less, avidly by g polypeptide chains than that in HbA and, this assist it to load oxygen in the placenta while, maternal haemoglobin is unloading oxygen thereby, enabling the foetal body cells to utilise O2., , Table : Respiratory pigments, Name of the, respiratory pigment, , Metal, present, , Colour, , 1. Haemoglobin, 2. Haemocyanin, , Iron, Copper, , Red, Blue, , 3. Haemoerythrin, 4. Chlorocruorin, 5. Pinnaglobin, 6. Echinochrome, 7. Vanadium, , Iron, Iron, Manganese, Iron, Vanadium, , Red, Green, Brown, Red, , , Features, Plasma of some annelids (e.g. earthworm and Neries), Plasma of crustaceans (e.g. prawn), some snails (Pila),, cephalopods (e.g. Sepia), Blood cells of some annelids (e.g. polychaete Magelona), Plasma of some annelids (e.g. polychaete sabella), Plasma of some molluscs (e.g. Pila), Coelomic fluid of sea urchin (echinoderm), Blood of many tunicates (urochordates)., Ciona contains vanadium pigment in the plasma, Special green blood cells called vanadocytes, of Ascidia.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 382, , ŕďőĽę– ĐĽŐńŐĹť, , 2,3 DPG, 2,3 DPG (diphosphoglycerate) is present in, the red cells of adult blood. It competes for, oxygen binding sites in the haemoglobin, molecule. As it binds to the b chain of, haemoglobin A (especially deoxy HbA) it causes, the right shift of dissociation curve resulting in, higher P50., l, l, , l, , l, , l, , l, , l, l, , l, , l, , Dissociation curve for myoglobin of muscle is, hyperbolic., Respiratory quotient or, volume of CO 2, ., RQ =, volume of CO 2 utilized, Methaemoglobin is usually present at the time of, asphyxiation (condition caused by increase in CO2, concentration in tissue)., At high altitude, RBC of human blood will, increase in number in response to the air being, less dense. More number of RBC’s are needed to, trap O2 from rarefied air having low PO2 (partial, pressure of O2)., Respiratory centre (RC) regulates normal, breathing (movement of diaphragm and intercostal, muscles) and also automatically adjusts the, breathing rate to varying requirements of body, during stress conditions., The respiratory centre is sensitive to the increased, carbon dioxide or increased acidity in the, cerebrospinal fluid and an increased PCO2 in the, blood acts because CO2 rapidly diffuses from the, blood to the cerebrospinal fluid., Respiratory centre is located in the medulla, oblongata and pons varolii., Respiratory centre can be divided into an, inspiratory and expiratory centre in the medulla,, an apneustic centre and a pneumotaxic centre., Respiratory centre comprises 3 groups of, specialized nerve cells (neurons) – doral, respiratory group (located in dorsal position of, medulla), ventral respiratory group (in, ventrolateral part) and a pneumotaxis centre in, dorsal part of pons., Pneumotaxis centre acts as an inhibiting nerve, centre and is connected to both inspiratory and, expiratory parts of respiratory centre., , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Ventral respiratory group issues signals for both, inspiration and expiration when high level of, pulmonary ventilation are required in deep, breathing., Dorsal respiratory centre does not issue any, impulse for expiration therefore it is referred to as, inspiratory centre., Stretch receptor present in walls of bronchi and, bronchioles transmits signals through vagus nerves, to the dorsal group of respiratory centre to “switch, off” inspiratory signals., Hering breuer reflex serves as a protective, mechanism for preventing excessive lung inflation., The bronchial tree is connected to the brain, through the vagus nerve., COPD (chronic obstructive pulmonary disease) is, a general term of several lung diseases that includes, chronic bronchitis, emphysema and chronic, asthma., The two primary causes of COPD are cigarette, smoking and alpha 1 antitrypsin deficiency. Air, pollution and occupational dusts may also, contribute to COPD, especially if the person, exposed to these substances is a smoker., Bronchitis is an inflammation of the bronchi, causing them to over secrete mucus, which in turn, causes coughing to get it up., Emphysema is an inflammation or abnormal, distention of the bronchiole or alveolar sac resulting, into the loss of elasticity., Emphysema is a nonreversible pulmonary, disease causing extreme shortness of breath and, eventual death. In this disease, the bronchial tubes, of the lungs become blocked with mucus plugs and, infection, inhibiting passage of air into and out of, the alveoli (air sacs). The disease is characterized, by destruction of these sacs which lose their, elasticity, swell and rupture thereby interferring with, the exchange of oxygen and carbon dioxide in the, breathing process. Emphysema is often caused by, smoking., Tuberculosis is a specific infectious disease caused, by Mycobacterium tuberculosis. The disease, primarily affects lungs and causes pulmonary, tuberculosis. It can also affect intestine, meninges,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ŕĚďŚĺĽňĹ– ·– ◄ŤĘĺďňĹĚ– Őě– ◙ďřĚř, , l, , bones, joints, lymph glands, skin and other tissue, of the body., TB is spread by coughing. The earliest symptoms, of active TB are fever, night sweats and weight, loss. Later there is cough and blood may appear in, phlegm (sputum)., The TB skin test is based upon the type IV, hypersensitivity reaction (also called delayed or, cell mediated hypersensitivity). Delayed, hypersensitivity is a function of helper T, lymphocytes, not antibody. If a previous TB, infection has occurred, then there are sensitized, lymphocytes that can react to another encounter, with antigens from TB organisms. For the TB, skin test, a measured amount of tuberculin, purified protein derivative (PPD) is injected, subcutaneously to form a small wheal, typically, on the forearm. In 48 to 72 hours, a positive, reaction is marked by an area of red induration, that can be measured by gentle palpation (redness, from itching and scratching doesn’t count)., , l, , l, l, , l, , l, , l, , Sputum, skin test of tuberculin (mantoux test), and Xrays are carried out to diagnose tuberculosis., BCG (Bacillus calmette guerin) vaccine gives, considerable protection against the disease., Antituberculosis drugs are streptomycin, para amino, salicylic acid (PAS), rifampicin, ethambutol etc., When TB affects animals like cattle then this is, known as bovine tuberculosis which may, sometimes be communicated to man (via milk)., Asthma is an allergic reaction that causes, constriction of the bronchiole muscles, thereby, reducing the air passages thus the amount of the air, that can get to the alveoli., Pneumonia is an infection of the alveoli. It can be, caused many kind of both bacteria (eg., Streptococcus pneumoniae) and virus., Tissue fluids accumulate in the alveoli reducing, the surface area exposed to air., , l, , l, , l, , l, , l, , 383, , Occupational lung disease are caused due to, exposure to harmful substances like gas, fumes or, dust present in the environment where a person, works. E.g. silicosis (exposure to silica), asbestosis, (exposure to asbestos dust). Fibrosis is caused due, to proliferation of fibrous connective tissue of upper, part of lung., The occupational diseases express symptoms after, exposure of 10 15 years or more. Such diseases, can not be cured, but can be prevented by adopting, following measures –, –, Minimising the exposure of harmful dust., –, Use of protective gears and clothing by the, workers., –, Regular health check up., Lung cancer is technically known as bronchogenic, carcinoma and is caused due to uncontrolled, multiplication of the basal cells of the bronchial, epithelium., Lung cancer develops in lung tissue in the, following steps:, –, First, a thickening and callusing of cells lining, the bronchi appears., –, Cilia are lost so it is impossible to prevent, dust and dirt from settling in lungs., –, Next, cells with atypical nuclei appear in, callused lining., –, A tumor consisting of disordered cells with, atypical nuclei develops as cancer in situ., –, When some tumor cells break free and, penetrate other tissue (metastasis), cancer, spreads., –, Tumor may grow until bronchus is blocked,, cutting off air supply to lungs., –, Entire lung collapses; trapped secretions, become infected causing pneumonia or lung, abscess., The only treatment is surgery (pneumonectomy), where a lobe or whole lung is removed.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 384, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 40, , Locomotion & Movement, l, , l, , l, , l, , l, , l, l, l, , l, , l, , Locomotion is the ability to move in a particular, direction in its environment, which requires a, propulsive force acting against a supporting, structures., For various functions like shifting from an, unfavourable conditions, to get food, to find partner,, for laying eggs or giving birth, living organisms, move from one place to another place. This type, of movement is called locomotion., In living organism movement is autonomic which, occurs self stained whereas in nonliving organism, movement is induced which occurs by external, force., Locomotion includes –, –, running (e.g., horse, Ostrich), –, walking (e.g., cattle), –, jumping (e.g., Baboon), –, somersaulting (e.g., Hydra, leech), –, crawling (e.g., snakes), –, climbing (e.g., squirrel), –, flying (e.g., birds, butterfly), and, –, swimming (e.g., fishes, Paramecium), Some animals are sedentary i.e., they are fixed at, one place, e.g., sponges, several coelenterates (e.g.,, corals, Obelia), Herdmania and many echinoderms., Locomotion cannot occur without movements of, body parts., Movement of body parts is performed by all, organisms including plants., Animals are able to move their body parts by the, movement of external body parts or internal, organs., Movement of external body parts includes the, movement of limbs, head, trunk, jaws, tentacles,, eye balls, pinna of the ear (to collect sound) etc., Movements of internal organs are peristalsis and, peristaltic movement, movement of diaphragm, ribs,, movement or uterine wall (for giving birth) etc., , l, l, l, , l, l, , l, , l, , The scientific study of body movements is known, as kinesiology., Animal exhibit three basics types of movements., These are amoeboid, ciliary and muscular., Amoeboid movement occurs by means of, temporary protoplasmic outgrowths (called, pseudopodia) due to flow of protoplasm in any, direction, e.g., Amoeba, macrophages and, leucocytes., Ciliary movements occurs with the help of cilia,, e.g., Paramecium., Muscular movement is caused by the property of, contractibility of muscles, which is used effectively, for locomotion., Movements in vertebrates are performed by two, types of independent systems – muscular system, & skeletal systems., Movement of internal organs are controlled by, muscular system while locomotion and, movement of most external body parts are, brought about by coordination of both the system., , MUSCULAR SYSTEM, l, , l, l, , l, , A system of different muscles present in body, specialised to perform various movements inside, the body as well as its external part is called, muscular system., In humans, the muscles are of three types – skeletal,, smooth and cardiac muscles., Skeletal muscles are attached to the bones by, tendons and help in the movement of the parts, of skeleton. These muscles are under the control, of conscious mind and are called voluntary, muscles., Under the microscope, skeletal muscles exhibit, transverse strips and hence are designated as, striated muscles.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▌ŐĘŐŇŐŚĽŐň– ·– ▐ŐŢĚŇĚňŚ–, l, , l, , l, l, l, , l, l, , l, l, l, l, l, l, l, , l, l, l, l, l, l, , Smooth muscles are nonstriated and involuntary, muscle. These are found inside the wall of the, hollow internal organs (e.g. alimentary canal,, blood vessels, reproductive tract)., Cardiac muscles are also striated and are not, under voluntary control. These occurs exclusively, in the wall of heart., Study of components, structure and functioning of, muscular tissue is known as myology/sarcology., Human body has about 640 types of muscle., According to function or movement muscles are, classified into flexor, extensor, adductor, abductor,, pronator, supinator, elevator, depressor, rotator,, sphincter, dilator, invertor and evertor., Prime movers muscles acts most powerfully during, any given movements., Flexors muscles bend one part of a limb on another, at a joint, eg. biceps. It brings the forearm towards, the upper arm., Extensor muscles extends or straightens a limb,, eg. triceps., Adductor muscles brings a limb towards the mid, line of the body, e.g., lattissmus dorsi., Abductor muscles pulls a limb away from the, midline of the body, e.g. deltoides of shoulder., Pronator muscles turns the palm downwards or, backwards, e.g. pronator teres., Supinator muscles turns the palm upward or to, forward, e.g. supinator., Elevator muscles rises a part of the body, e.g., massetor., Depressor muscle lower a part of the body, e.g.,, depressor mandibularis moves down the lower jaw, to open the mouth (pectoralis major is the, depressor muscle for the wings of the birds)., Rotator muscle rotates a part of the body, e.g.,, pyriformis which raises and rotates the thigh., Sphincter muscle decreases the size of an opening, e.g., pyloric sphincter., Dilator muscle increases the size of an opening,, e.g., iris., Turn the sole inward and outwards are called, invertor and evertor respectively., Synergists muscles act together to produce, movement., Antagonistic muscle are those muscles which act, in opposition to other muscle. Eg. the bicep muscle, extended from shoulder to radius bends or flexes, the arm at elbow whereas triceps extending from, ulna to shoulder straightens the arm., , 385, , Important muscles, Largest muscle – Gluteus maximum (buttock), Smallest muscle – Stapedius of stapes, Strongest muscle – Massetors of jaws (lower), Longest (or Tailor) – Sartorius (run from the hip to, muscle, knee), Quadriceps Femoris., Boxer’s muscle – Serratus anterior, l, , l, , l, l, l, l, l, , l, , l, , l, l, l, l, l, , l, l, , Striated muscle (also called skeletal muscle) are, mostly attached to bones and takes part in moving, them like levers., The molecular components of skeletal muscles, are – (i) contractile proteins, (ii) enzymes, (iii) fats, and carbohydrates, (iv) organic phosphates; and, (v) ions., Important nonprotein organics are ATP,, phosphocreatine, creatine, urea and glycogen., Potassium is the most abundant mineral element, in muscle., Myofibrils (proteinaceous fibrils) are the, contractile elements of muscle fibre., Sarcomere are the contractile units of myofibrils., Each muscle fibre is elongated and syncytial, (multinucleate). Its membrane is called, sarcolemma and its cytoplasm is called, sarcoplasm., Skeletal muscle fibre shows transverse striations in, the form of regular alternate dark A band, (anisotropic) and light I (isotropic) bands., At the centre of I band, a fine dense Zline (or, Krause’s membrane) is present which divides the, myofibrils into sarcomeres., Sarcomere is the area between two Zline., Hzone is found at the centre of A band and M, Line or Hensen’s line., Myosin is a major protein present in the thick, filament of skeletal muscle fibre., Actin is the contractile protein of muscle present, in thin filament., The myosin molecule consists of head and a tail, components. The head part conform a cross, bridges with actin and has contractile as well as, ATPase activity., Sliding filament theory of muscle contraction was, proposed by A.F. Huxley & H.E. Huxley in 1954., According to this theory, during muscle, contraction, actin filaments slide inward on the, myosin filament of Aband with the help of cross, bridges to reduce the length of the sarcomeres.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 386, , l, l, , l, , l, l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Release of calcium ions from sarcoplasmic, reticulum trigger the muscle contraction process., The calcium ions result in movement of troponin, and tropomyosin on their thin filaments, and this, enables the myosin molecule heads to ‘grab and, swivel’ their way along the thin filament, this is the, driving force of muscle contraction., Contraction of a muscle is caused by actomyosin, which is formed in the presence of calcium ions, and energy (obtained from ATP), actin and myosin., In resting muscles, ATP combines anaerobically, with creatine to form creatine phosphate., When muscle contracts creatine phosphate breaks, down to produce ATP., During muscle contraction conversion of pyruvic, acid to lactic acid proceeds anaerobically and, chemical energy is changed into mechanical, energy., During muscle contraction –, –, Both I and H zones progressively shorter and, eventually disappear., –, Length of A band remains unchanged,, –, Distance between two lines shortens and size, of sarcomere decreases by 6070%., Energy for contraction of muscle fibre is provided, by ATP (produced by creatine phosphate &, respiratory breakdown of glycogen/glucose)., Biochemical and electrical changes occurring, during muscle contraction were explained by Albert, SzentGyorgi in 1942., Based upon the sarcoplasmic contents, situation of, nuclei & number of formed elements, two types of, fibres are recognised in striated muscle – white, fibre & red fibres., White muscle fibre are fast muscle fibre which, lack myoglobin and have fewer mitochondria., These muscle perform fast work for short, duration as a result of which these muscle fibre, get fatigued quickly. Eg. eye ball muscle, flight, muscle of sparrow., Red muscle fibre are slow muscle fibre possessing, red haeme protein (called myoglobin) and abundant, mitochondria., These muscle can perform slow sustained work, over long period without getting fatigued. Eg., extensor muscle of back & flight muscle in kites., Sharpey’s fibre are calcified bundles of white &, yellow fibres perforating and holding periosteal, bone lamellae., , l, l, , l, , l, l, , l, l, l, , l, , l, l, l, , l, , l, l, l, l, , l, l, , Threshold stimulus is the minimum strength of, stimulus required to initiate muscle contraction., Oxygen debt is the requirement of extra oxygen, during recovery phase of muscle over a period of, resting stage., The extra oxygen required during recovery phase, is for regeneration of oxymyoglobin, restoration of, depleted ATPs & CP and oxidation of lactic acid., Cori cycle was discovered by Cori & Cori., Cori cycle is the passage of lactic acid produced, in muscle into liver where 80% of it is changed, to glycogen/glucose for continued supply to, muscle., The force produced during contraction of muscle, is called muscle tension., Muscle fatigue is a failure of muscle to respond, a fresh stimulus after a prolonged previous activity., Muscle fatigued is caused due to accumulation, of lactic acid, consumption of stored glycogen., ATP changes in neuromuscular junction which is, sensitive to lactic acid., Rigor mortis is a condition in which non, availability of ATP molecules, enzymes and oxygen, results in nonseparation of actin & myosin, filaments leading to body stiffening after death., Refractory period is the interval during which a, muscle fibre fails to respond to a second stimulus., It is 0.002 0.005 sec. in a skeletal muscle fibre, & 0.1–0.2 sec. in a cardiac muscle fibre., A single isolated contraction of a muscle fibre in, response to a single stimulus and relaxation is called, muscle twitch., Latent period is the interval between the, application of appropriate stimulation and, contractions., It is 0.01 sec. in skeletal muscle and upto 30 sec., in visceral muscle., The duration for which the muscle remains in, contracted state is called contraction period., It is 0.04 sec. in skeletal muscle & upto 20 sec. in, a visceral muscle., Relaxation period is the interval required for the, contracted muscle to regains its original relaxed/, elongated state., It is 0.05 sec. for a skeletal muscle & 2.3 sec. for, visceral muscle., The ability of muscles to get stretched is called, tensility.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▌ŐĘŐŇŐŚĽŐň– ·– ▐ŐŢĚŇĚňŚ, , SKELETAL SYSTEM, l, , l, , l, l, , l, l, l, , l, l, , l, , l, , The skeletal system (bones and joints), working, interdependently with the skeletal muscle system, (or voluntary or striated muscles), provides basics, functions that are essential to life. These are , –, Protection protects the brain & internal, organs, –, Support maintains upright posture, –, Blood cell formation haematopoiesis, –, Mineral homeostasis, –, Storage stores fats & minerals, –, Leverage a lever is a simple machine that, magnifies speed of movement or force. The, levers are mainly the long bones of the body, and the axes (fulcrum) are the joints where, the bones meet., Skeletal systems are commonly divided into three, types external (an exoskeleton), internal (an, endoskeleton), and fluid based (a hydrostatic, skeleton), though hydrostatic skeletal systems may, be classified separately from the other two since, they lack hardened support structures., Exoskeleton is the hard protective and supportive, framework present on the outside of the body., Exoskeleton is found in both invertebrates (e.g.,, shell of snails, bivalves, corals, sclerites of insects), and vertebrates (e.g., claw, nails, horns, feather,, scales etc.), Exoskeleton can be epidermal or mesodermal., Epidermal/ectodermal exoskeleton occurs in, mammals, birds and many reptiles., Mesodermal/dermal exoskeleton occurs in fishes, (scales) and some reptiles (crocodiles, turtles and, tortoises)., Endoskeleton consists of those hard parts which, are present inside the body of the animal., The functions of endoskeleton are support,, protection, muscle attachment, movement, blood, cell formation and mineral reservation etc., Hydrostatic skeletons are similar to a waterfilled, balloon. Located internally in cnidarians (coral,, jellyfish, etc.) and annelids (leeches), among others,, these animals can move by contracting the muscles, surrounding the fluidfilled pouch, creating pressure, within the pouch that causes movement., Animals such as earthworms use their hydrostatic, skeletons to change their body shape as they move, forward from long and skinny to short and stumpy., , l, , l, , l, , l, , l, l, , l, l, , l, , l, , l, , l, l, l, l, l, , 387, , The human skeleton is made of individual or joined, bones (such as skull), supported and supplemented, by structure of ligaments, tendons, muscles,, cartilage & other organs., A ligament is a short band of tough fibrous, connective tissue composed mainly of long, stringy, collagen fibres., Ligaments connect bones to other bones to form, a joint. Some ligaments limit the mobility of, articulations, or prevent certain movements, altogether., Tendon is a fibrous, strong, connective tissue that, connects muscle to bone. Damage to a tendon can, result in the inability to flex or extend at a joint., Cartilage is a type of dense connective tissue., Cartilage is composed of cells called chondrocytes, which are dispersed in a firm gellike ground, substance, called the matrix., Cartilage contains no blood vessels and nutrients, are diffused through the matrix., Cartilage is found in the joints, the rib cage, the, ear, the nose, in the throat and between, intervertebral discs. There are three main types of, cartilages: hyaline, elastic and fibrocartilage., Types of bones are spongy bones, compact bones,, diploid bones, cartilage bones, sesamoid bone,, investing or dermal or membranous bone and, visceral bone., Bones are classified according to shape and size, into (i) long bones, which make up the limbs., (humerus, tibia etc.), (ii) short bones, which are, grouped together to strengthen our skeleton (meta, carpels), (iii) flat bones, which protect our body, and provide a place for muscles to attach (scapula),, and (iv) irregular bones (vertebrae, tarsals of, ankle)., Spongy bones (cancellous bones) have bony matter, as bar or trabeculae and space filled with red bone, marrow., Spongy bone occur at the ends of long bones, vertebrae, sternum and ribs., Function of long bones in mammals is to provide, support and to produce RBC’s and WBC’s., Epiphyseal plates at the extremities of long bones, help in elongation of bones., In birds, the spongy bone have air filled spaces and, called as pneumatic bones., Compact bones have compact / dense matrix and, occur in the form of lamellae. E.g. clavicles and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 388, , ŕďőĽę– ĐĽŐńŐĹť, Axial skeleton, (80 bones), , Endoskeleton of Man, (206 bones), , Skull Hyoid bone Ear ossicles Vertebral column (in, Ribs, Sternum, (1), (in head), (3 + 3 = 6) neck & trunk and, (12 pair = 24), (1), (22), tail if present) (26 are, visible, 33 in embryonic, stage), Forelimb (60), Limbs, (120), Hindlimb (60), , Girdles, (6), , l, , l, , l, l, l, , l, l, l, , l, l, , l, l, , scapulae of pectoral girdle, innominates of pelvic, girdle, arm bones and leg bones., Diploid bones have both compact (on surface) and, spongy (inside) region, e.g., femur, humerus, flat, bones of skulls and ribs., Cartilage bones or replacing bones are produced, by endochondral ossification (i.e., internal, ossification of cartilage). E.g., limb bones, vertebrae, girdle bones (except clavicle), occipital and, sphenoid., Sesamoid bones are produced through ossification, of tendons, e.g., patella., Investing bones are formed by transformation of, connective tissues, e.g., clavicle, face bones., Visceral or heterotypic bones occur separate from, the rest of the skeleton. E.g., os cordis (heart of, deer), os penis (penis of rodents, bats and some, carnivores) etc., The total number of bones in adult human is 206., Human skeleton (endoskeleton) is divided into, two main parts axial and appendicular skeleton., The axial skeleton is present on the median, longitudinal axis of the body. It consists of 80 bones, in adult man., Axial skeleton consists of skull, vertebral column,, sternum and ribs., Appendicular skeletonis situated at the lateral sides,, which is actually extends towards from the principle, axis. It consists of 126 bones in adult man., Appendicular skeleton consists of pectoral and, pelvic girdles, and bones of arms and legs., Skeleton of head is called skull which rests upon, the upper end of vertebral column., , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , Pectoral (4), Pelvic (2), , The bony structure of skull consists of the, following parts: (i) bones of cranium (ii) ear ossicles, (iii) hyoid bone, and (iv) bones of the face., Cranium ( or brain box) is formed by 8 bones,, these are: 1 frontal bone, 2 parietal bones, 2, temporal bones, 1 occipital bone, 1 sphenoid, bone and 1 ethmoid bone., Newborns have temporary holes in the cranium, called fontanelles. They are present as long as the, brain growth occurs i.e., the anterior fontanelles, closes at 18 months., Cranium bones contain sinuses. Sinuses are air, spaces lined with mucous membrane that reduce, weight of skull and give resonant sound to the voice., Two mastoid sinuses drain into middle ear;, mastoiditis inflammation can lead to deafness., Occipital has foramen magnum for passage of, spinal cord and two occipital condyles for the, fixation with atlas vertebra., Ear ossicles are three small bones the incus, (anvil), malleus (hammer) and stapes (stirrup) that, transmit (and amplify) vibrations of the tympanum, across the middle ear to the oval window which, transfers them to the inner ear., Hyoid bone (horse shoe shaped bone) is situated, in the wall of the upper part of the throat just above, the larynx (it is not a bone of skull proper)., Hyoid support tongue and provides insertion to, some tongue muscle. It consists of an elliptical, main part (or body) and the two processer called, greater and lesser cornia., The skeleton of face consists of 14 bones. These, are : 2 zygomatic bones, 2 maxilla, 2 nasal bones,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▌ŐĘŐŇŐŚĽŐň– ·– ▐ŐŢĚŇĚňŚ, , l, , l, l, l, l, l, , l, l, , l, l, , l, , l, l, l, , l, , l, , l, , 2 lacrimal bones, 1 vomer, 2 palatine bones, 2, inferior nasal chamber, 1 mandible (the only, movable bone in the skull of man)., Functions of skull are to protect the brain, to protect, the special sense organs, provide rigid walls of a, respiratory passage, for cutting and masticating its, food with the help of jaws etc., The bone common to cranium and face is frontal., The skull bones fit together by sutures., Sella turcica is the depression in sphenoid bone of, skull that lodges pituitary body., Vertebral column is a string like vertebrae which, lies in the middorsal line of the neck and trunk., Function of vertebral column is to carry weight, of body during motions as well as standing and it, gives flexibility to the animal during movement of, head., Vertebral column permits movement, and protect, the spinal cord., The number of bones in vertebral column is 33, but vertebrae consists of 26 bones because 5 sacral, vertebrae fused to form one sacrum, and 4 coccygeal, vertebrae fused to form one coccyx., Human vertebral formula is C7T12L5S5Cd4., Cervical vertebrae are present in the neck,, thoracic vertebrae in the chest, lumbar vertebrae, in abdomen, sacrum vertebrae between the, innominate bones of the pelvic girdle and coccyx/, caudal vertebrae are present in tail region., Atlas, the first cervical vertebra has reduced, centrum, rudimentary neural spine and concave, superior articular facets to provide nodding, movement of head., The second cervical vertebra axis is characterised, by odontoid process., Odontoid process fits into canal of atlas to provide, head with sideways rotation., Lumbar vertebrae are largest, heaviest and, strongest as they bear weight of the abdominal, viscera., Vertebral column serves as a strong beam from, which viscera are suspended by mesentries in, the body cavity., Vertebral column displays four curves to enhance, balancing powers and firmness for upright posture, of the body., These curvatures are cervical, thoracic, lumbar, and pelvic (= sacral)., , l, , l, , l, l, , l, l, l, , l, , l, l, l, l, , l, , l, l, , l, , 389, , Between the centre of adjacent vertebrae there are, elastic pads of fibrocartilage, the intervertebral, discs which provide mobility to the vertebrae,, check undue frictions and take up shocks., Displacement of the vertebrae from its normal, position due to displacement or degeneration of a, part of intervertebral disc is called slip disc., Sternum is a flat bone present just under the skin, in the middle of the front of the chest., Sternum protects the internal organs of thoracic, region, provide surface for muscle attachment, and helps in respiratory mechanism., Sternum is longer in male than female., Sternum of man consists of three portions, manubrium, body and xiphoid process., Ribs which form the bony lateral walls of thoracic, cage are usually 12 pairs but occasionally there, may be 11, 13 or even 14 pairs., The first 7 pairs of ribs which reach the sternum, directly are known as true rib; the 8th, 9th and, 10th pair of ribs which are attached indirectly to, the sternum or attached to coastal cartilage of, seventh rib are known as false rib and the last, pairs (11th and 12th) of ribs fall for short of the, sternum and are known as floating ribs., Floating ribs are so called because these ribs are, imperfectly formed and do not reach the sternum., Thoracic cage or rib cage is formed of thoracic, vertebrae, sternum and ribs., Pectoral (shoulder) girdle consists of 4 bones–2, clavicles and 2 scapulae., Clavicles or collar bones is a slender S shaped, bone that articulate with the manubrium of the, sternum., Scapula is a large triangular, flat bone which, presents a shallow articular surface known as, glenoid cavity., Coracoid process is a knob like inwardly bent, fused scapula blade., Glenoid cavity articulate with head of humerus, and it also help in the attachment of the arm, muscles., The primary function of the pectoral girdle is to, provide an attachment point for the numerous, muscles that allow the shoulder and elbow joints, to move. It also provides the connection between, the upper extremities (the arms) and the axial, skeleton.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 390, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Each arm consists of 1 humerus, 1 radius, 1 ulna,, 8 carpal bones, 5 metacarpal bones and 5 digits, (14 phalanges)., Phalangeal formula is 2, 3, 3, 3, 3., Humerus has rounded head at the proximal end,, a middle rod like shaft with deltoid ridge for, attachment of muscle and a pulley like trochlea at, the distal end., Humerus is also called funny bone., Funny bone is a highly sensitive area at the back, of the elbow where the ulnar nerve passes close, to the surface of the skin in a groove between, end prominences of the humerus (the upper arm, bone) and the ulna (the large forearm bone). A, blow to the area causes the nerve to compress, against bone, producing a characteristic tingling, in the forearm and the last two fingers., , l, l, l, l, l, , l, , l, l, l, , l, l, , l, , Humerus is the longest bone in the upper, extremities., Radius is shorter than ulna., Ulna has an olecranon process for forming elbow., Thumb of hand is called pollex., Pelvic girdle (also called hip girdle) is formed by, two innominate (= no name) bones (hip or coxal, bones)., Each coxal bone consists of three separate parts –, the ilium (short and straight bone), the ischium, (lower elongated bone, running parallel to vertebral, column), and the pubis (inner, smaller bone)., The coxal bones are also called the ossa coxae., Pelvic girdle has deep depression called, acetabulum in which the head of femur fits., Obturator foramen is present as a large oval gap, between the pubis and ischium. The foramen, forms passage for nerves and blood vessels., Pelvic girdle articulate with the legs and supports, the posterior region of the trunk., The pelvic girdle serves several important, functions in the body. It supports the weight of, the body from the vertebral column. It also protects, and supports the lower organs, including the urinary, bladder, the reproductive organs, and the developing, foetus in a pregnant woman., The pelvic girdle differs between men and, woman. In a man, the pelvis is more massive and, the iliac crests are closer together. In a woman,, the pelvis is more delicate and the iliac crests are, farther apart., , l, l, , l, l, , l, , l, , l, , l, l, l, l, l, , l, , l, , l, , l, , l, , l, , These differences reflect the woman’s role in, pregnancy and delivery of children., Each leg consists of 1 femur, 1 tibia, 1 fibula, 1, patella (knee cap), 7 tarsal bones, 5 metatarsal, bones and 5 digits (14 phalanges). Phalangeal, formula is 2, 3, 3, 3, 3., Patella is a sesamoid bone., Femur, tibia and fibula bones together support, the shank of the leg. The tarsals form the ankle,, metatarsals form the sole and phalanges form the, the digits of the foot., The femur is the longest, largest, and strongest, bone in the body whose head fits into the, acetabulum of hip girdle., The tibia connects to the femur to form the knee, joint and with the talus, a foot bone, to allow the, ankle to flex and extend., The tibia is larger than the fibula because it bears, most of the weight, while the fibula serves as an, area for muscle attachment., Fibula is shorter, thinner and slender., Tibio fibula is the longest bone in frog., Smallest bone in human body is stapes of middle, ear. It is approximately .11 inches (.28 cm) long., The structural arrangement of tissue by which bones, are joined together are called joints., According to the mobility joints are of three, types – fixed or fibrous, slightly movable and, synovial joint., In fibrous or immovable joints there is no movements, between the bones concerned (e.g., sutures and joints, between the teeth and the maxilla, etc.)., Cartilaginous or slightly movable joint allows, very slight movements. E.g., cartilaginous joints, include the pubis and the joints between the, vertebrae., Synovial joints / freely movable joints, (diarthrosis) are perfect joints in which bones are, not fused with each other., Synovial joints are further classified according to, the movements they permit. The main types are –, ball and socket joints, hinge joints, gliding joints,, pivot joints, saddle joints and ellipsoid joint, etc., Ball and socket joints have one end like a ball and, other like a cup shaped socket, e.g., shoulder joint, and hip joint., Saddle joint is an imperfectly developed ball and, socket joints in which one bone is movable on
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▌ŐĘŐŇŐŚĽŐň– ·– ▐ŐŢĚŇĚňŚ, , l, , l, l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , another fixed bone in many direction, e.g.,, carpometacarpal joint of human thumb., Ellipsoid or angular joint have one movable bone, on another bone in two planes. E.g., wrist or, radiocarpal joint of humans, toes and sole., In this joint one articular end is oval and convex, while the other end is elliptical and concave., In pivot joint articular end of one bone is fixed, while that of the other can rotate over it. E.g.,, between atlas and axis in humans, upper ends of, radius and ulna., In hinge joint articular end of one bone is deeper, convex and that of other is deeper concave, allowing, movement in one plane. E.g., elbow joint, knee joint, (condylar joint), ankle joint, interphalangeal joints., In gliding joint articular ends of two bones are, either flat or slightly curved to allow sliding or, gliding movement. E.g, bones of palm and sole,, between prezygapophyses and postzygapophyses, of vertebrae., Osteology is the study of bone with their structure,, nature, development and functions., Arthritis is painful inflammation and stiffness of, joints caused by infection, allergy, hormonal, disturbances and faulty food., Osteoarthritis is a tearing of articular cartilage, and development of bony lumps at places causing, pain, stiffness due to inhibited secretion of synovial, fluid and permanent bending., In rheumatoid arthritis, a hard tissue deposits, over articular cartilage along with higher secretion, of synovial fluid causing pain and stiffness., Gout is the accumulation of uric acid crystals in, the region of joints which results in painful, movements., Dislocation In this case, the bone at the joints are, dislodged from their positions. E.g., the ball of one, bone may slip out of the socket., Bursitis is inflammation of the bursae present, within synovial joint as small membrane bound, pockets which stores synovial fluid. It is caused by, physical injury or constant pressure on a single, joint for a long time., Osteomyelodysplasia is a condition characterized, , l, , l, l, , l, l, , 391, , by thinning of the osseous tissue of bones and, increase in size of the marrow cavities, attended, with leukopenia and fever., Osteopetrosis is a hereditary disease marked by, abnormally dense bone, and by the common, occurrence of fractures of affected bone., Injury to joint due to overstretching or tearing of, ligament or tendon is called sprain., Osteoporosis is an agedependent disorder,, characterised by increased fragility of bones which, become prone to fracture. Imbalance of hormones, like thyrocalcitonin, parathyroid and sex hormones,, deficiencies of calcium and vitamin D, are the major, causative factors of the disease., Fracture is a breaking of bone accidently., Fracture is of 4 types green stick fracture (simple, crack without breaking into 2 pieces, generally occurs, in growing children), simple fracture (breaking into, 2 parts which remain nearby), compound fracture, (breaking into 2 or more parts with some protruding, out), comminuted fracture (breaking into more than, two pieces) and evulsive fracture (a small piece, breaks but remains attached to ligament)., Phantom Limbs, Phantom Limb Pain (PLP) is a serious condition, that occurs when a person who has lost a part, of their body though amputation, trauma or loss, of nervous connections in an appendage,, perceives that the limb is still there and, experiences sensations coming from this area. It, was first described in 1886 by S. Weir Mitchell,, an American neurologist. The phantom sensation, can occur right after the amputation or many, months or years later. Many phantom limb, sensations ocur after some injury to the site of, the amputation. Thus, a person who was born, without a limb, and did not experience any type, of phantom sensation could suddenly find, themselves experiencing one if some type of, injury occurred to the stump. Phantom limbs, help with the use of prosthetics. It’s easier to, use some type of prosthetic device if there are, phantom sensations associated with the limb.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 392, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 41, , Body Fluids & Circulation, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Body fluid is any of the fluids found within animals,, including blood, lymph, tissue fluid, urine, bile,, sweat and synovial fluids., Body fluids are generally involved with the, processes of transport, excretion or lubrication., Body fluids allow the distribution of oxygen and, nutrients to the tissues and organs and the transport, of waste products from the tissues, enabling their, elimination from the body., Circulation of body fluids are of two types–, intracellular and extracellular., Intracellular circulation occurs inside the cell, through cyclosis., It occurs in unicellular organism like Paramecium,, Amoeba etc., Extracellular circulation occurs outside the body, cell, i.e., extracellular fluid that circulates in the, body for transport of materials., Extracellular circulation may be extra organismic, circulation (outside water circulates in the body of, the organism) and intraorganismic circulation, (involves circulation of body fluids). Eg. of intra, organismic circulation are parenchymal, circulation (flatworms), coelomic circulation, (roundworm), blood vascular system (vertebrates, and higher invertebrates)., Depending upon the medium of transportation, circulatory system is divided into water and blood, vascular system., Water circulatory system is a system of circulation, of water drawn from outside medium into body, spaces for transport of respiratory gases, wastes and, food articles, eg. sponges (water canal system),, coelenterates (gastrovascular system) and starfish, (ambulacral system)., Blood vascular system is a system containing a, , l, l, l, , l, l, l, l, , l, , special body fluid or blood, blood vessels and a, pumping organ or heart for moving it., Blood vascular system occurs in vertebrates and, higher invertebrates (from annelids onwards)., Blood vascular system may be open or closed., In open circulatory system, blood flows partly, through vessels and partly through haemocoelomic, spaces., The haemocoelomic spaces are called blood sinuses., The blood in open circulatory system is called, haemolymph., Open circulatory system is found in some molluscs, and in some arthropods., In a closed circulatory system, the blood vessels, form a complete circuit in the body, carrying blood, to and away from the organs., Closed circulatory system occurs in annelids, (earthworm), some molluscs (cephalopods),, echinoderms and all vertebrates., , BLOOD, l, , l, l, , l, l, l, , Blood is a fluid connective tissues that circulates, through the heart, arteries, capillaries and veins,, carrying nutrients and oxygen to the body cells., Haematology is the study of blood forming tissues, and circulating blood components., The functions of blood are – to deliver nutrients, hormones, and oxygen to tissues; to collect and, dispose of the waste from cellular metabolism; to, deliver specialized cells to tissues for protections, against the external environment; and to prevent, leakage by a closing gaps in blood vessels., Blood measures about 5–5.5 litres in an adult man, constituting 30–35% of total extracellular fluid., Major elements of blood consists of cellular (RBC,, WBC, platelets) and fluid (plasma) elements., Plasma is the relatively clear liquid protein and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲Őęť– ◘ńśĽęř– ·– ►ĽŕĘśńŐň, , l, , l, , l, , l, l, , l, , l, , l, l, l, , l, , l, , l, , salt solution which carries the RBC, WBC and, platelets., Plasma makes up 55 percent of the blood volume,, the remaining components compose 45 percent, of the blood., About 95% of plasma consists of water. As the, heart pumps blood to cells throughout the body,, plasma brings nourishment to them and removes, the waste products of metabolism., Plasma contains three major classes of plasma, proteins viz. serum albumin, serum globulins and, fibrinogen. They serve as a source of proteins for, tissue cells., Albumin and globulins retain water in blood, plasma by their osmotic effects., Plasma functions in (a) transport (b) body, immunity (c) prevention of blood loss (d) retention, of fluid in blood (e) maintenance of blood pH, (f) uniform distribution of heat all over the body,, and (g) conduction of heat to skin for dissipation., Red blood cells (or erythrocytes) are relatively, large microscopic cells without nuclei (in mammals, except camel and llamas)., The name of the red blood cell reflects the bright, red colour of the cell that occurs when oxygen is, attached to the haemoglobin., Haemoglobin is the gas transporting protein, molecule that makes up 95% of a red blood cell., Each red blood cell has about 270,000,000 iron, rich haemoglobin molecules., Optimum amount of haemoglobin in male is about, 16 gm/100 ml blood and 13–14 gm/100 ml blood, in female., Haemoglobin is a protein which is bright red in, color. Individual RBCs are strawcolored, but in, the aggregate they appear brightred if the, haemoglobin is bound to oxygen (i.e. oxygenated), and bluishpurple if not., Haemoglobin contains the element iron, making it, an excellent vehicle for transporting oxygen and, carbon dioxide. As blood passes through the lungs,, oxygen molecules attach to the haemoglobin. As, the blood passes through the body’s tissue, the, haemoglobin releases the oxygen to the cells. The, empty haemoglobin molecules then bond with the, tissue’s carbon dioxide or other waste gases,, transporting it away., In each cubic millimeter of blood, about 5 million, red blood cells are present., , l, , l, , l, l, , l, , l, l, , l, l, , l, l, , l, , 393, , The life span of RBC is 120 days after which they, are broken down by the spleen and the Kupffer, cells in the liver., Average life of RBC of transfused blood, (oxalated) is 60 days and fetal RBCs (with, nucleus) is 180 days., Process of RBC formation is known as, erythropoiesis (completed in 72 hours)., The ageing cells (RBC) swell up to a spherelike, shape and are engulfed by phagocytes, destroyed, and their materials are released into the blood. The, main sites of destruction are the liver and the spleen., The heme constituent of haemoglobin is eventually, excreted as bilirubin., The functions of erythrocyte are –, –, Oxygen transport in the blood from the lungs, to all the cells and tissues of body., –, Assists with the transport of carbon (IV) oxide, from the tissue to the lung., –, Regulating the acid base balance of blood,, thus preventing large changes in pH., –, Also assists when a blood clot is formed., An insect larva has red blood. The larva of genus, Chironomus is called ‘Blood worm’. The red, colour of this larva is due to haemoglobin,, which has the power of attracting and storing, oxygen and giving it off to the tissues as they, require it., Leucocytes are larger than red blood cells and, have a definite nucleus., Leucocytes can be divided into two components–, granulocytes (polymorphonuclear leucocytes), and agranulocytes (mononuclear leucocytes)., Neutrophil, eosinophil and basophil are, categorised as granulocytes., Neutrophils (constitute 60 70%) can be, recognized by their segmented nuclei and the, presence of abundant, small, pale staining granules, in their cytoplasm., Neutrophils are the most abundant and are, produced in red bone marrow., Neutrophils are active in phagocytosis, play a role, in the healing of wounds and repairing worn, out and damaged tissue; and prevent infections, from spreading to other tissues of the body., Eosinophils (motile phagocytic cell) constitutes, upto 3%, are characterized by bilobed nucleus, having clearly visible granules in the cytoplasm.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 394, , ŕďőĽę– ĐĽŐńŐĹť–, , Basophils are characterized by very large granules., Their nuclei often remain invisible because of the, granules. They are probably like mast cells of, connective tissue., Nongranular leucocytes (or mononuclear, leucocytes) can be grouped into two classes –, lymphocytes and monocytes., Lymphocytes are produced in the spleen, tonsils, and lymph nodes and are the smallest of the white, blood cells., Lymphocytes are of two types – B and, T lymphocyte., Lymphocytes are involved in the synthesis and, distribution of antibodies in the blood., The B cells are responsible for humoral or, antibody immunity and T cells are responsible, for cellular immunity., Monocytes are the largest amongst all types of, leucocytes with a rounded nucleus., Monocytes are motile and phagocytic in nature., Individual white blood cells in man usually live, about 10–13 days., Some white cells (called lymphocytes) are a, major part of the immune system. Other white, cells (called granulocytes and macrophages), protect our bodies from surrounding and, destroying bacteria, virus, fungi or other, parasites. They also have the function of getting, rid of old, unwanted blood cells as well as foreign, matter such as dust and asbestos., Leukaemia, also called blood cancer, is an, uncontrolled production of leucocytes., Platelets or thrombocytes are cells that clot blood, at the site of wounds (by producing platelet factor, thromboplastin)., Platelets are nonnucleated, round or oval biconvex, disc like bodies., Individual platelets measures about 1/3 the size of, , l, , l, , l., , l, l, l, , l, l, l, , l, l, , l, l, , l, l, , l, l, , l, , l, l, , l, , l, l, , l, , l, , l, , l, l, , red cells., Platelet have a life span of 9 10 days (about a week)., Mechanism of blood clotting at the site of injury, protects the organism by stopping bleeding or, haemorrhage., Clotting time is the time required for blood to, coagulate. It usually varies from 2 to 8 minutes., Serum is a pale yellow fluid that separates from, the blood upon coagulation,when all cellular, elements are removed., Anticoagulants like heparin, sodium or potassium, oxalate are chemical substances which prevent, blood clotting., The cation necessary for coagulation of blood is, calcium., Platelet aggregation and fibrin formation both, require the proteolytic enzyme thrombin. Platelets, are the source of thromboplastin., Lymph, chiefly made of plasma and leucocytes, is an interstitial fluid, present between the cells of, a tissue., If the formation rate of lymph exceeds the rate of, its return to blood then oedema occurs., Blood groups are the special characteristic of blood, in human and related primates due to the, presence of genetically controlled antigens and, antibodies., Antigens are relatively large proteins molecules, that provide the biological signative of an, individuals blood type., Within blood there are substances called antibodies, which distinguish particular antigen from others, and causing bursting or agglutination of the red, blood cells when alien antigen are found., More than 20 different blood group systems are, recognized in medicine. Of these, the best known, are the ABO system and the Rh system., The antigens of ABO systems are A, B and H., The H antigen is the precursor to the A and B antigens., , Table : Types of blood group (ABO), Blood Group Antigens, on RBCs, , Antibodies, in serum, , Genotypes, , Can donate to, , Can recieve from, , A, , A, , antiB, , AA or AO, , A & AB, , O, A, , B, , B, , antiA, , BB or BO, , B & AB, , O, B, , AB, , A and B, , Neither, , AB, , AB, , O, A, B, AB, , O, , Neither, , antiA and antiB, , OO., , O, A, B, AB, , O
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 395, , ▲Őęť– ◘ńśĽęř– ·– ►ĽŕĘśńŐň, , Table : Blood group of parents on the basis of their children’s blood group, S.No, , Blood Group of Child, , 1., , O, , 2., , A, , 3., , B, , 4., , AB, , M olecule connective, tissue. Red coloured due, to RBC when oxygen, attached to haemoglobin., , One Parent, , Second Parent, , Can Not Be, , O, A, B, O, A, B, A, B, O, A, B, AB, A, , A, B & O, A, B & O, A, B & O, A & AB, A, B & O, A, B & O, B & AB, B & AB, B & AB, B & AB, A & AB, A, B & AB, B & AB, , AB, AB, AB, B&O, AB, AB, O&A, O&A, O&A, O&A, O&B, O, O, A, , Haematology, is, , Life span, , is the study of, , BLOOD, , Different blood groups, , Components, , Function, , Plasma, Fluid portion of, blood in which, cellular elements, are suspended., , A, Cellular elements, three types, , RBC, (enucleated), Responsible for, carrying oxygen and, CO2 via haemoglobin, content in the, cytoplasm between, lungs and tissue., , l, l, l, l, , Basophil, L e as t, abundant, , AB, (universal, acceptor), , O, (universal, donor), , B, , WBC, Platelets, (colourless,, (nonnucleated and colourless), nucleated), Source of thromboplastin, Protects against, (involved in blood clotting), invading organisms., , two types, , Granulocytes, Eosinophils, , RBC ... 120 days, WBC ... 1013 days, Platelets ... 910 days, , High count, , Low count, , Leukaemia, , Leukopenia, , leads to, , leads to, , Agranulocytes, Neutrophil, Most, abundant, , Lymphocyte, Monocyte, Main functional, Largest precursors of cells of, cells of immune, mononuclear phagocytic, cells, system, To deliver nutrients and oxygen to tissue., To collect and dispose of waste from cellular metabolism., To deliver specialised cells to tissue for protection against the external environment., To prevent leakage by closing gaps in the blood vessels.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 396, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Water is the main component of blood. Almost, 70% of the body is water, most of which is contained, in and around cells. The blood plasma maintains, the water content of cells in the tissues., , CIRCULATORY SYSTEM, l, , l, , l, , l, l, l, l, , l, l, , l, l, l, , l, l, l, , Sir William Harvey, first demonstrated that the, blood makes a complete circuit of the body, being, pumped out of the heart through one set of vessels, and returning to the heart via a different set., Circulatory system of human beings is of closed, type and it consists of blood vascular system and, lymphatic system., Blood vascular system consists of blood, (described earlier), blood vessels and heart as, their components involved in circulation., Blood vessels are intricate networks of hollow tubes, that transport blood throughout the entire body., Vasa vasorum is the blood vessel which supplies, blood to the blood vessel itself., Three varieties of blood vessels are – arteries,, veins and capillaries., Arteries are elastic vessels that transport blood, (oxygenated) away from the heart towards the, other body tissue., Pulmonary artery is the only artery which carries, deoxygenated blood., Aorta is the largest artery of the body which, orginates from the heart and branches out into, smaller arteries., The smallest arteries are called arterioles which, branches into capillaries., Arterioles receives blood from the arteries and, carries it to the capillaries., Walls of artery consists of three layers–, –, Tunica intima – The innermost smooth layer, lining endothelium, connective tissue, elastic, tissue., –, Tunica media – A middle layer of smooth, involuntary muscle and elastic fibres., –, Tunica externa – An external layer consisting, mainly of inelastic white fibres (collagen, fibres)., In artery, tunica media is well developed and, thicker, in vein, tunica externa is well developed., Veins transport blood (deoxygenated) to the heart, (except pulmonary vein)., Pulmonary vein conveys oxygenated blood from, the lungs to the left atrium of the heart., , l, l, l, , l, , l, , l, , l, l, l, l, , l, l, l, l, l, l, l, , l, , l, , Veins contain pocket valves which prevent the back, flow of blood., Largest vein in the human body is inferior vena, cava., Capillaries are extremely thin blood vessels with, a diameter as small as 59 in man. These form, capillary plexus between arterioles on one end, and venules on others., Capillaries, made up of tunica interna (single layer, of endothelium), transports blood from arteries to, the veins., Body contains three types of capillaries continuous, capillary (found in brain, connective tissue and, skeletal muscle), fenestrated capillary (found in, endocrine tissues, ciliary body of eye, etc), and, discontinuous capillary (found in liver sinusoids)., Capillary beds are the sites where white blood, cells are able to leave the blood and defend the, body against harmful invaders., Human heart is situated in the thorax between the, lungs with its apex resting on the diaphragm., The heart measures 12 cm in length and 9 cm in, breadth., Heart is the busiest organ of the body., The wall of the heart consists of three layers :, the external covering layer or epicardium, the, intermediate cardiac muscular tissue or, myocardium and the internal layer or, endocardium in contact with the blood., Myocardium does not fatigue due to alternate rest, and activity and nonformation of lactic acid., Heart is enclosed in a double fibroserous sac called, pericardium., No neurons are present in the walls of heart., The mammalian heart consists of 4 chambers right, and left atrium, right and left ventricle., The walls of the atria are thinner than those of, the ventricles., Auricle is divided by an interatrial or inter, auricular septum., On this septum, a depression, called fossa ovalis, is present which is the remnant of embryonic, foramen ovale (through which both the auricles, communicate with each other)., The right atrium recieves deoxygenated blood, from superior vena cava, inferior vena cava and, coronary sinus., The left atrium recieves oxygenated blood from, two lungs through four pulmonary veins.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲Őęť– ◘ńśĽęř– ·– ►ĽŕĘśńŐň–, l, l, , l, , l, , l, l, , l, l, , l, l, l, , l, , l, l, , Right and left ventricles are separated by an, interventricular septum., Left ventricle is thicker than right ventricle, because it has to push blood to all the body parts, at a much greater pressure., Walls of the ventricles possess a network of low, ridges or columnae carnae and a few large muscular, projections or papillary muscles/musculi, papillares., The right ventricles contains a moderator bands, that extends between upper papillary muscle and, interventricular septum., Bicuspid valve or mitral valve is present in, between the left atrium and left ventricle., Tricuspid valves consists of three flaps or cusps, and present between the right atrium and right, ventricles., Semilunar valves (pulmonary valve and aortic, valve) are present where artery leaves the heart., Valves of eustachian (rudimentery membranous, falciform fold) is present at the opening of inferior, vena cava., Valves of thebesius or coronary valve is present, at the opening of coronary sinus., Strong fibrous strings connecting bicuspid and, tricuspid valves are known as chordae tendinae., The valves of heart maintains unidirectional flow, of blood and prevent its regurgitation in the, opposite direction., Varicose veins are enlarged, twisted, painful, superficial veins resulting from poorly functioning, valves., Blue whale has the largest heart., The world’s first heart transplant was performed by, Prof. Christian Barnard on December 21, 1967., Sinus venosus is a thin walled chamber of, vertebrate embryos heart. Sinus venosus receives, blood from the umbilical, vitelline and common, cardinal veins (i.e., from the chorion or placenta,, from the yolk sac, and from the embryo). The, sinus venosus of the primitive heart opened into, the common atrium. As development proceeds, the opening of the sinus venosus moves to the, right atrium. As the sinus venosus moves to the, right the venous drainage from the rest of the, body, the head, the vitelline and umbilical veins, also move to the right. A small part of the sinus, venosus still lies behind the left side of the heart, to become the coronary sinus., , l, , l, , l, l, , l, l, , l, l, , l, , l, l, l, , l, , l, , l, , l, , 397, , Heart beat is the rhythmic contraction and relaxation, of the heart which include one systole (contraction, phase) and one diastole (relaxation phase)., The normal rate of heart beat is 70 72/min in, adult human., Smaller animals have much higher heart beat, rate than the larger animals because they have, high metabolic rates and hence need greater, action of heart to pump more oxygen and, nutrients to tissue. Eg. 200/min in rabbit, 500/min, in sparrow whereas elephant has 25/min., The heart beat is of two types neurogenic &, myogenic., In neurogenic heart, contraction is initiated by a, nerve ganglion situated in the vicinity of the heart,, i.e., heart beat originated by nervous regulation., The hearts of most arthropods and some annelids, like Arenicola, Lumbricus etc. are neurogenic., In a myogenic heart contraction is initiated by a, special node of modified heart muscle, the sino, atrial (SA) node, present in the wall of right, atrium close to the point of entry of the vena cava., The heart of molluscs and vertebrates are of, myogenic type., SA node is the first to originate the cardiac impulse, and determines the role of the heart beat, hence also, known as pace maker., Origin of heart beat and its conduction is represented, as SA node ® AV node ® Bundle of His ® the, bundle branches ® Purkinje fibres., AV (auriculoventricular) node acts as pace setter., AV (atrioventricular) bundle or Bundle of His, was discovered by His (1893)., A set of specialized muscle strands which originates, in the AV node and pass downwards in the inter, ventricular septum is known as purkinje fibres., The bundle of his and the purkinje fibres convery, impulse of contraction from the AV node to the, myocardium of the ventricles., Rate of heart beat is controlled by nerves,, hormones (epinephrine or norepinephrine, secreted, by adrenal medulla), other factors [including, inorganic ions (K, Na & Ca), temperature, pH,, CO2 etc]., Nervous regulation of heart beat includes two, pairs of nerves arising from the cardiac centre, located in medulla oblongata and spinal cord., These nerves are acceleratory and inhibitory, which affect the working of heart rate by changing
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 398, , l, , l, l, l, l, l, l, , l, , l, , l, l, , l, l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , the heart rate and by changing the strength of, contraction of the heart., The acceleratory nerves consists of sympathetic, fibres and also known as adrenergic nerve as they, releases a substance sympathin (comprising, hormones adrenaline and noradrenaline) which, increases the fibre permeability to sodium and, calcium ions., Inhibitory nerves forming parasympathetic, elements are a pair of vagus nerves (X)., If sympathetic nerve and vagus nerve stimulated,, the heart rate increases and decreases respectively., Foramen of panizzae is present in between two, systemic arches of the heart., The heart is supplied with the arterial blood by the, cornonary arteries., Cardiac output is the amount of blood flowing, from the heart over a given period of time., Cardiac output = stroke volume (the volume of, blood pumped by heart/heart beat) × heart, rate (ventricular systole/min) Þ 70 ml × 72/min, = 5040 ml/min Þ about 5 litre/min., Cardiac output in relation to unit surface area of, body is cardiac index. Its normal value is, 3.3 lt/min/sq.m., The cardiac cycle refers to the sequence of events, which takes place during the completion of one, heart beat., In human being, the cardiac cycle occurs about 72, times per minute., These events comprises contraction (systole) and, relaxation (diastole) of the chambers of heart,, associated with opening and closing of the heart, valves., Cardiac cycle is completed in 0.88 sec., Heart sounds may be heard by stethoscope during, each cardiac cycle., First heart sound lubb is created by the closure, of atrioventricular valves at the beginning, of ventricular systole and opening of semilunar, valves., Second heart sound dup is created at the end of, ventricular systole when the semilunar valve closes, and the AV valves open., The first sound has a duration of 0.15 second and, a frequency of 2545 Hz. The second sound lasts, about 0.12 seconds with a frequency of 50 Hz., Murmurs are abnormal sounds heard in various, parts of the vascular system., , l, , l, l, , l, l, l, , l, , l, , l, l, l, , l, , l, l, , l, , l, , l, l, , The major cause of cardiac murmurs is a disease, of the heart valves. It may arise due to improper, closing of any heart valve or in patients with, interventricular septal defects., ECG is the recording of electrical changes that, accompany the cardiac cycle., Waller (1887) first recorded the electrocardiogram but, Einthoven (1908) studied ECG in detail, therefore he, got Nobel prize in 1924 for the discovery of ECG., Einthoven is considered to be the father of, electrocardiography., Normal ECG is composed of P wave, QRS wave, & T wave., P wave, a small upward wave, indicated the, depolarisation of the atria, caused by activation, of SA node., QRS wave begins as a small downward deflection, (R) & continues as a large upright (R) & triangular, wave ending as downward wave (S) at its base., QRS wave represents ventricular depolarization,, & caused by impulse of the contraction from AV, node through bundle of his & purkinje fibres and, the contraction of ventricular muscles., Twaves indicates ventricular repolarization., Enlargements in Q&R waves indicates myocardial, infarction., ST segment is elevated in acute myocardial, infarction and depressed when the heart muscles, recieves insufficient oxygen., Twave is flat when the heart muscles recieve, insufficent oxygen as in atherosclerotic heart, disease. It may be elevated when the body’s, potassium level is increased., Blood, pressure, is, measured, by, sphygmomanometer in the brachial artery., Factors which affect blood pressure are cardiac, output, total blood volume, blood viscosity,, resistance, elasticity of arteries., Blood pressure is measured during systole, the, active pumping phase of the heart, and diastole, the, resting phase between heartbeats., Systolic and diastolic pressures are measured in, units of millimeters of mercury (abbreviated, mm Hg) and displayed as a ratio – Systolic pres, sure (mmHg)/Diastolic pressure (mm Hg)., The average blood pressure is expressed as, 120/80 mm Hg., The increase in the blood pressure beyond, 140 mm Hg. (systolic) and 90 mm Hg. (diastolic)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲Őęť– ◘ńśĽęř– ·– ►ĽŕĘśńŐň, , l, , l, , l, l, , l, l, l, l, l, l, , l, , l, , l, l, , is referred to as high blood pressure. A sustained, rise in the arterial blood pressure is known as, hypertension., The reason for hypertension are stiffening of, arterial walls due to ageing, thickening of arterial, walls due to cholesterol deposition, chronic vaso, constriction of arterial walls, varicose veins,, obesity, hormones etc., High blood pressure may harm heart, brain and, kidneys. In brain it may cause haemorrhage or in, farction. In long run it may cause congestive heart, disease and affect kidney leading to renal failure., Hypotension is a low blood pressure with systolic, below 110 mm Hg and diastolic below 70 mm Hg., Hypotension is caused by low metabolic rate,, anaemia, chronic vasodilation of arterioles, starva, tion, nervous disorder etc., Marey’s law of heart is the inverse relationship, between rate of heart beat and blood pressure., Heart rate is pulse per minute., Pulse is the alternate expansion and elastic of recoil, (contraction) of an artery with each systole., Pulse can be detected in superficial artery like, radial artery of wrist and temporal artery., The difference between systolic and diastolic, pressure is called pulse pressure., Double circulation is the passage of blood twice, in the heart through separate pathways for, completing one cycle., Double circulation is present in lung fishes,, amphibians, birds, reptiles and man where, arteriovenous heart (means when it receives both, venous or deoxygenated and arterial or oxygenated, bloods) is present., The advantage of double circulation is that the, blood can be sent to the lungs to pick up oxygen, and then be returned to the heart to be pumped, again before travelling around the body. The blood, therefore is pumped through the capillary blood, (which slows it down and reduces its pressures), then receives another pump before it enters an, other capillary bed. Double circulatory systems, are therefore high pressure system. In this there, is no mixing of the oxygen rich blood and oxygen, poor blood in the heart., Double circulation consists of pulmonary and, systemic circulation., In pulmonary circulation movement of the blood, takes place from the heart to the lung and vice versa., , l, , l, l, , l, , l, l, l, , l, , l, l, , l, , l, , l, l, , l, , 399, , In systemic circulation, the movement of blood, takes place between heart and different parts of the, body except lungs., Systemic circulation has arterial and venous, system., Arterial system comprises all arteries coming out, from the heart and supplying blood to different, parts of the body. Whereas venous system com, prises all the veins that bring blood to heart. Two, main arterial vessels are pulmonary arch and aorta., Two main veins are 2 precavals and 1 post caval., Single circulation is present in fish where blood, from the heart first goes to the gills to collect, oxygen, but continues round the whole body before, returning into heart., The heart of fish is called venous heart as it, receives deoxygenated blood., Microcirculation deals with the flow of blood from, arterioles to capillaries or sinusoids to venules., ‘Blue baby’ is the name given to an abnormal human, baby who has a hole in the ventricular septum so, that oxygenated and less oxygenated blood mix., The foetal circulation involves the exchange of, materials between the foetus and mother by means, of placenta., The foetal circulation differs mainly from the adult, one by the presence of 3 major vascular shunts., These shunts are – ductus venosus (between, umbilical vein and inferior vena cava), foramen, ovale (between the right and left atrium i.e., opening, in interatrial septum) and ductus arteriosus (between, the pulmonary artery and descending aorta)., Coronary circulation is the flow of oxygenated, blood from the ascending aorta to the heart muscles, and the return of deoxygenated blood from the heart, muscle to the right atrium., A portal vein is the vein which collects blood from, the organ by a set of capillaries and distributes that, blood into a second organ through another set of, capillaries instead of sending into heart., There are three types of portal systems hepatic,, hypophysial and renal., Hepatic portal system occurs in all vertebrates and, is meant for taking blood from digestive tract,, pancreas and spleen into liver., The system has a large hepatic portal vein that is, formed by four veins splenic (from spleen),, inferior mesenteric (from rectum and distal part, of colon), superior mesenteric (from small
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 400, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , intestine, caecum and proximal part of colon) and, gastroepiploic (from stomach and pancreas)., Hypophysial portal system is a minor portal, system that occurs in higher vertebrates. The system, consists of a single hypophysial portal vein which, passes into anterior lobe of pituitary gland and, breaks up into capillaries there., This system is meant for pouring hormones secreted, by hypothalamus directly into the anterior part of, pituitary., Renal portal system occurs in lower vertebrates, (fishes and amphibians), reduced in reptiles and, aves, and is absent in mammals., It consists of renal portal veins that bring blood, from posterior part of the body directly into, kidneys., Lymphatic system of man consists of lymphatic, capillaries, lymphatic vessels, lymph nodes, lymphatic, ducts, lymph and other lymph organs like spleen., Lymphatic system serves as an intermediary, (middle man) between the blood and the tissues., Lymph is an interstitial fluid (tissue fluid), present, between the cells of a tissue and it has the same, composition like plasma except it lacks RBCs and, large plasma proteins., All the lymph collected from the entire left side of, the body, the digestive tract and the right side of, the lower part of the body flows into a single major, vessel, the thoracic duct., Lymphatic system helps to maintain fluid and, balance in the tissues and also have a major role, in the defence against infection., Cysterna chyli is a sac like structure situated infront, of the upper lumbar vertebrae on the right of the, abdominal aorta., Spleen is the largest component of lymphatic, system., Spleen acts as the reservoir for red corpuscles,, helps in formation of agranulocytes, antibodies,, erythropoiesis etc., Spleen is termed as ‘grave yard’ of RBC because, fragment of red cells, old and dead cells are constantly, being removed from the blood streams by it., Cords of Billroth are blood spaces found in red, pulp of spleen., Oedema occurs when lymph capillaries fail to, return lymph to the blood, fluid accumulates in the, tissue resulting in a local swelling., Haematoma is localised collection of clotted blood, , l, , l, , l, , l, l, l, , l, , l, , l, , l, , l, l, l, l, l, l, l, , l, , in a tissue or organ due to injury rupturing of a blood, vessel., Angina pectoris is a sudden recurring thoracic pain, radiating to arms, especially left arm, due to, ischaemia of myocardium and precipitated by effort, or excitement., Myocardial infarction is the complication due to, reduced blood supply to heart wall, pain,, perspiration, nausea, ECG changes., Rheumatic heart is the heart with insufficient, blood supply to its muscles due to rheumatic, disorder or fever in childhood., Cardiomegaly is hypertrophy of heart., Inflammation of heart is carditis., Atherosclerosis is wall thickening and narrowing, of lumen of medium and large arteries. In, atherosclerosis, yellowish plaques (atheromas) of, cholesterol and other lipids are deposited within, intima and inner media of arteries., Arteriosclerosis is the hardening of arteries due the, deposition and thickening due to precipitation of, calcium salts with cholesterol., Palpitations is awareness of heart beat or a feeling, of having a rapid and unusually forceful heart beat,, especially if they last for several hours or recur, over several days and/or cause chest pain,, breathlessness or dizziness., Fibrillation is a condition in which the heart muscle, is contracting very rapidly but in an uncoordinated, fashion. There are atrial and ventricular fibrillation., Ventricular fibrillation is immediately life, threatening unless it can be stopped by, defibrillation. A machine called a defibrillator,, which gives a DC voltage shock, is used to do this., Tachycardia is above normal heart beat/pulse., Brachycardia is below normal heart beat/pulse., Phonocardiogram is an instrument for amplifying, and recording of heart sounds., Lowest level of glucose is present in hepatic vein., Highest level of amino acids is present in hepatic, vein., Highest level of urea is in hepatic vein and lowest, is in renal vein., Electric shock is given to stabilize the heart in case, of arrythmia or revive the heart in case of cardiac, arrest., Angiology is the study of blood vascular and, lymphatic system.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŤĘŕĚŚŐŕť– ☼ťřŚĚŇ–, , 401, , Chapter 42, , Excretory System, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , The tissues and organs associated in the removal, of waste products (called excretion) constitute the, excretory system., Excretion is the “process of eliminating (from an, organism) the waste products of metabolism of, nitrogenous substances like amino acids and nucleic, acids and other materials that are of no use., Some of these structures constitute the urinary, system which is involved in the synthesis,, separation and elimination of mainly nitrogenous, waste products and other mineral salts., The urinary system produces, stores and, eliminates urine after it produces and modifies a, urinary filtrate consisting of a large volume of, hypotonic blood filtrate rich in serum proteins., The main aim of the excretion is to maintain a, constant body temperature by removing excess heat, and maintain a constant internal environment in, association with the other system of the body (called, homeostasis)., Excretion is an essential process in all forms of, life. In one celled organisms wastes are discharged, through the surface of the cell. The higher plants, eliminate gases through the stomata, or pores, on, the leaf surface. Multicellular animals have special, excretory organs., The waste product could be nitrogenous, non –, nitrogenous, chemicals, bile pigments, excess of, water or CO2., Metabolism of carbohydrates and fats produces, CO2 and H2O which are easy to remove. Their, excretion is effected through lungs (expired air),, skin (sweat) or kidneys (urine)., Carbon dioxide produced as the waste product during, respiration, diffuses out of the cells into the lung, tissue and leaves the body everytime we exhale., Other excretory products are pigments, mostly, formed by the breakdown of haemoglobin;, drugs etc., , l, , l, , l, , l, , l, l, , l, , l, l, l, , l, l, , Protein metabolism produces nitrogenous waste, material such as ammonia, which is the basic, nitrogenous catabolite of protein, formed by, breakdown of amino acids., Removal of the amino group (NH2) is known as, deamination and it converts the amino acid into, a keto acid., Nitrogeneous waste have the ability to change, the pH of cells and interferes with membrane, transport functions and may denature enzymes., Some common nitrogenous excretory products are –, Ammonia (very toxic and requires large amount, of water, eg. aquatic invertebrate such as Amoeba,, sponge, Unio, star fish etc.); urea (less toxic, eg., cartilaginous fishes, amphibians and mammals),, uric acid (least toxic, eg. reptiles, birds and, cockroaches), trimethylamine oxide (eg. marine, bony fish, mollusca, crustaceae), ornithuric acid, (birds), guanine, creatinine etc., The main three nitrogenous wastes are –, ammonia, urea and uric acid., Animals excreting ammonia, urea and uric acid, are respectively called as ammonotelic, ureotelic, and uricotelic animals., Ammonia is highly toxic and soluble in water, with wh ich it forms ammonium hydroxide, (NH4OH) which injure cell directly by alkaline, caustic action. Hence excretion of ammonia, requires large amounts of water to be lost from, the body., Ammonia is the first metabolic waste product, of protein metabolism., No energy is required to produce ammonia., Ammonotelic organisms (without excretory system), includes all aquatic invertebrates, bony fishes,, aquatic amphibians., The terrestrial animals excrete urea as, nitrogenous waste product., Urea is produced in liver from some proteins
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 402, , ŕďőĽę– ĐĽŐńŐĹť, , (ornithine, citrulline, arginine) and other nitrogen, compound by deamination process in presence of, arginase enzyme., Urea is the end product of protein or amino acid., Urea is eliminated in the form of urine., Formation of urea cycle, also known as the urea, or ornithine cycle, is a cycle of biochemical, reactions occurring in many animal organisms that, produces urea from ammonia (NH4+ ) due to lack, of water., This cycle was the first metabolic cycle discovered, by Krebs and Hensenleit, 1932., The urea cycle consists of five reactions two, mitochondrial and three cytosolic (Refer table, given below)., Earthworm excrete ammonia when sufficient, water is available but it eliminates urea when, water is not available in good quantity., In anurans (amphibians) the larval tadpole excrete, ammonia, while the adults produce urea., Uric acid is the nitrogenous waste product of, terrestrial animals such as birds, many reptiles,, insects and land snails that do not have constant, access to water or rather have limited access to, water., Conversion of ammonia to uric acid and its, subsequent elimination requires lesser amount of, water as it is comparatively less soluble in water, and less toxic as compared to ammonia., Uric acid is a more complex molecule than urea, so it requires more energy to produce., Xanthine oxidase is needed in production of, uric acid., , l, l, l, , l, l, , l, , l, l, , l, , l, l, , l, l, l, l, l, , l, , l, , l, , l, , l, , l, , Bilirubins are the toxic bile pigment formed in, liver during disintegration of dead RBCs., In some reptiles and insects the uric acid is further, changed into allantoin., Marine teleost fishes excrete a large proportion, of nitrogen as trimethylamine oxide., Guanine is a metabolic waste of nucleotide, metabolism, found in spider and penguin., The regulation of water content and salt, concentration in the body of an organisms is called, osmoregulation., Osmoconformers are organisms that show changes, in the body fluid concentration according to the, concentration of external environment, e.g., most, of marine invertebrates., Osmoregulators are organisms that maintain a, fixed osmotic concentration in the body fluid despite, changes in the external environment., Marine invertebrates and cartilaginous fish, (chondrichthyes) are isotonic in which the, concentration of solutes in isotonic animals is, approximately equal to that of their environment., As a result, they do not gain or lose water., Birds and reptiles living near the sea consume a, large amount of salt in their diet. Nasal salt glands, remove this excess salt from their body by secreting, a concentrated salt solution., The kidneys of sea mammals (example seal, whales,, porpoise) are able to maintain a constant salt, concentration in their bodies by producing urine, having high concentration of salt., Kangaroo rats (a desert mammal) never have to, drink water. Their water comes from metabolic, , Table : Reactions in urea cycle, Step, , Reactant, , Product, , Catalyzed by, , Location, , 1., , 2ATP + HCO3– + NH4+, , Carbamoyl phosphate + 2ADP + Pi, , CPSI, , Mitochondrial, , 2., , Carbamoyl phosphate +, ornithine, , Citrulline + Pi, , OTC, , Mitochondrial, , 3., , Citrulline + aspartate +, ATP, , Argininosuccinate + AMP + PPi, , ASS, , Cytosolic, , 4., , Argininosuccinate, , Arg + fumarate, , ASL, , Cytosolic, , 5., , Arg + H2O, , Ornithine + urea, , ARGI, , Cytosolic, , CPSI – Carbamoyl phosphate synthetase; OTC Ornithine transcarbamoylase; ASS – Arginosuccinate synthetase;, ASL – Arginosuccinate lyase.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 403, , ◄ŤĘŕĚŚŐŕť– ☼ťřŚĚŇ, , l, , l, , l, l, , l, , l, l, , water released during cellular respiration and water, present in their food., In humans the main organs of excretion are the, kidneys and accessory urinary organs, through, which urine is eliminated, and the large intestines,, from which solid wastes are expelled., The skin and lungs also have excretory, functions.The skin eliminates water and salt in, sweat, and the lungs expel water vapour and, carbon dioxide., The waste products are eliminated by urination, and exhalation., Urination, also called micturition, is the process, of disposing urine from the urinary bladder through, the urethra to the outside of the body., The process of urination is usually under, voluntary control. When control over urination, is lost or absent, this is called urinary incontinence., Urinary retention refers to the inability to urinate., Perspiration is another excretory process which, removes salts and water, although the primary, purpose is cooling., , EXCRETORY SYSTEM, l, , l, l, l, , l, , l, l, , l, , The mammalian (human) urinary system consists, of – two kidneys (which form the urine), two, ureters (which conduct the urine from kidneys to, the urinary bladder), a urinary bladder (for storage, of urine) and a urethra (through which the urine, is voided by bladder contractions)., Human beings are ureotelic., Kidney (mesodermal in origin ) are excretory and, homoestatic organ., An average sized kidney measures 10 to 12 cm in, length, 5 to 6 cm in width and 3 to 4 cm in, thickness, each weighing about 150 g in adult, male and about 135 g in female., The human kidneys are beanshaped excretory, organs which filter wastes (especially urea) from, the blood and excrete them, along with water,, as urine., The medical field that studies the kidneys and, diseases affecting the kidney is called nephrology., Ureters are narrow tubes started as a pelvis within, kidney opening into a common urinary bladder, which opens outside through urethra., Urethra is a muscular tube that connect urinary, bladder and external opening of urinary tract., , Table : Organ of excretion in different animals, Organ of excretion, 1. Contractile vacuoles, & plasma membrane, , Name of animals, Protozoans, , 2. General body surface Hydra and sponges, 3. Renette cells, , Aschelminthes, , 4. Flame cells, (solenocytes) &, protonephridia, , Planarians, , 5. Nephridia &, chloragogen cells, , Earthworm (annelida), , 6. Malpighian tubules, , Insects (arthropoda), , 7. Coxal gland, , Spider, (arachnida,, phylumarthropoda), , 8. Green gland, , Prawn (crustacea, phylum, arthropoda), , 9. Keber’s organ or, organs of Bojanus, , Mollusca, , 10. Skin, , Amphibia, , 11. Kidneys, , Vertebrates, , l, l, , l, , l, , l, , l, , l, , Urethra is smaller in females and longer in males., Urethra conduct urine to the exterior. The urethral, sphincters keep the urethra closed except during, voiding of urine., Urinary bladder is sac like structure which stores, urine temporarily. Ureters and urinary bladder, are lined by flexible transitional epithelium., The kidneys are retroperitoneal, which means they, lie behind the peritoneum, the lining of the, abdominal cavity (means posterior part of the, abdomen).They are approximately at the vertebral, level T12 to L3., The right kidney sits just below the liver, the, left below the diaphragm and adjacent to the, spleen., The asymmetry within the abdominal cavity caused, by the liver results in the right kidney to be slightly, lower than the left one., A deep notch or concavity is present at the medial, border the hilus (hilum), and it is through this, region the blood vesselsrenal artery and vein, ureter, and nerves pass.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 404, , ŕďőĽę– ĐĽŐńŐĹť, , Types of kidney, – Types of kidneys are of following types –, archinephros, pronephric, mesonephric, and metanephric., – Archinephros, found in the larvae of some, cyclostomes, is the basic and ancestral form, of kidney., – Pronephric kidney or anterior kidney is, found only in cyclostomes and tadpole of, frogs. It is developed from anterior most, part of the nephrostome and are the, primitive kidney., – Mesonephric kidney or middle kidney is, found only in fish and frog. It is developed, just after pronephros in the nephrostome., – Mesonephric kidney is the second stage in, the development of the kidney., – Metanephric kidney or posterior kidney, (most advanced type) is found in reptiles,, birds and mammals. It is formed from the, posteriormost part of nephrostome, behind, embryonic mesonephros., l, , l, , l, , l, l, , l, , l, , l, , The upper parts of the kidneys are partially, protected by the eleventh and twelfth ribs, and, each whole kidney is surrounded by two layers, of fat (the perirenal fat and the pararenal fat), which help to cushion it., The outermost portion of the kidney is called the, renal cortex, which sits directly beneath the, kidney’s loose connective tissue capsule., The renal cortex is granular in appearance, because the tubules here are much convoluted, (proximal and distal convoluted tubules) and, contain malphigian corpuscles., Cortex is subdivided into alternating radial tracts, known as rays and labyrinths., The rays are radially straight since they contain, the straight parts of proximal tubules and the, collecting ducts. They are continuous with striated, medulla, hence called medullary rays., The labyrinths have a granular appearance because, the convoluted tubules, which compose them, are, cut irregularly., Deep to the cortex lies the renal medulla, which, is divided into 1020 renal pyramids in humans., Each pyramid together with the associated overlying, cortex forms a renal lobe., The lateral boundaries of the pyramid are formed, , l, l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , by the projection of the darker cortex which are, named as renal columns of Bertini., Renal medulla mainly contains loop of Henle,, collecting tubules and ducts of Bellini., The tip of each pyramid (called a papilla) empties, into a calyx, and the calyces empty into the renal, pelvis., The pelvis transmits urine to the urinary bladder, via the ureter., Each “kidney” receives its blood supply from the, renal artery, two of which branch from the, abdominal aorta., Due to the position of the aorta, the inferior vena, cava and the kidneys in the body, the right renal, artery is normally longer than the left renal, artery. The right renal artery normally crosses, posterior to the inferior vena cava., Upon entering the hilum of the kidney, the renal, artery divides into smaller interlobar arteries, situated between the renal papillae., At the outer medulla, the interlobar arteries branch, into arcuate arteries, which course along the border, between the renal medulla and cortex, giving off, still smaller branches, the cortical radial arteries, (sometimes called interlobular arteries)., Branching off these cortical arteries are the afferent, arterioles supplying the glomerular capillaries,, which drain into efferent arterioles., The walls of the afferent arteriole contain, specialized smooth muscle cells (juxtaglomerular, apparatus or cells) that synthesize renin., These juxtaglomerular cells or apparatus play a, major role in the reninangiotensin system, which, helps regulate blood volume and pressure., Juxtaglomerular apparatus or juxtaglomerular cells, includes – granular juxtaglomerular cells in the, afferent arteriole; macula densa of the proximal, part of the distal collecting tubule; and agranular, Polkissen or Lacis cells., Polkissen or lacis cells are situated in the angle, created by the entrance and exit of the afferent, and efferent arterioles of each glomerulus., Blood leaves the capillaries of the glomerulus via, an efferent arteriole and enters capillaries in the, medulla called peritubular capillaries, which, collect much of the water that was lost through, the glomerulus., Blood from these capillaries collects in renal
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 405, , ◄ŤĘŕĚŚŐŕť– ☼ťřŚĚŇ, , l, , l, , l, , l, , l, , venules and leaves the kidney via the renal vein., The renal veins connect the kidney to the inferior, vena cava. Because the inferior vena cava is on, the right half of the body, the left renal vein is, generally the longer of the two., Efferent arterioles of glomeruli closest to the, medulla (those that belong to juxtamedullary, nephrons) send branches into the medulla, forming, the vasa recta., Along with the loop of Henle, these vasa recta, play a crucial role in the establishment of the, nephron’s countercurrent exchange system., Counter current mechanism (the process due to, which the urine is made hypertonic) is regular, exchange of Na + ions between the ascending and, descending limbs of kidney., Blood supply is intimately linked to blood pressure., , l, , l, l, , l, , l, , l, , NEPHRON, l, , l, , l, , l, , The basic structural and functional unit of the, kidney is the nephron, of which there are more, than a million (approximately 1.3 million) in each, normal adult human kidney., Nephrons regulate water and soluble matter, (especially electrolytes) in the body by first filtering, the blood, then reabsorbing some necessary fluid, and molecules while secreting other, unneeded, molecules., Reabsorption and secretion are accomplished with, both cotransport and countertransport mechanisms, established in the nephrons and associated, collecting ducts., Nephrons eliminate wastes from the body,, regulate blood volume and pressure, control, levels of electrolytes and metabolites, and, , NEPHRON, , l, , l, , l, , l, , l, , regulate blood pH., Functions of nephron are vital to life and are, regulated by the endocrine system by hormones, such as antidiuretic hormone, aldosterone, and, parathyroid hormone., Two types of nephrons present in kidney are:, cortical and juxtamedullary nephrons., Cortical nephrons (70–80%) close to kidney, surface, have a shorter loop of Henle and, peritubular capillary network., Juxtamedullary nephrons (20–30%) at the, junction of renal cortex and medulla, have a longer, loop of Henle and vasa recta., Juxtamedullary nephrons are important in the, counter current mechanisms in which the kidney, concentrate the urine., Each nephron is composed of an initial filtering, component (the renal corpuscle) and a tubule, specialized for reabsorption and secretion (the, renal tubule)., The renal corpuscle filters out large solutes from, the blood, delivering water and small solutes, to the renal tubule for modification., The renal corpuscle (or Malpighian corpuscle) is, composed of a glomerulus and Bowman’s, capsule., The malpighian corpuscle is named after Marcello, Malpighi (1628 1694), an Italian physician and, biologist., Glomerulus is a capillary (fenestrated) tuft that, receives its blood supply from an afferent, arteriole of the renal circulation., The remainder of the blood not filtered into the, glomerulus passes into the narrower efferent, arteriole., , Types, , Differentiated into 5 regions, , Cortical nephron, Present at the periphery of cortex, Peritubular capillary is present, Acts in normal condition., , Juxtaglomerular nephron, Present towards the medulla of cortex, Peritubular capillary is absent, Renal capsule or Proximal convoluted Loop of Distal convoluted Collecting, Acts under stress i.e. function most, Malpighian body, tubule (PCT), tubule (DCT), tubule, Henle, Important when water is in short supply., Concentrates urine, Consists of two parts, Consists of two parts, , Bowman’s capsule Glomerulus Ascending limb of, loop of Henle, , Descending limb of, loop of Henle
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 406, , ŕďőĽę– ĐĽŐńŐĹť, , The glomerulus (plural glomeruli) in olfaction, is a structure in the olfactory bulb. It is made up, of a globular tangle of axons from the olfactory, receptor neurons in the olfactory epithelium and, dendrites from the mitral cells, tufted cells and, other cells types., Glomeruli are important waystations in the, pathway from the nose to the olfactory cortex., Each glomerulus receives input from olfactory, receptor neurons. The glomerulus is the basic, unit in the odour map of the olfactory bulb., l, l, , l, , l, , l, , l, , l, , l, , l, , l, , The diameter of the afferent arteriole is much, more than that of efferent arteriole., Bowman’s capsule (also called the glomerular, capsule) is a blind sac which surrounds the, glomerulus., Bowman’s capsule is composed of inner visceral, (simple squamous epithelial cells) and outer, parietal (simple squamous epithelial cells) layers., Bowman’s capsule is named after Sir William, Bowman (1816 1892), a British surgeon and, anatomist., The visceral layer lies just beneath the thickened, glomerular basement membrane and is made of, podocytes which send foot processes over the, length of the glomerulus., Foot processes interdigitate with one another, forming filtration slits that, in contrast to those, in the glomerular endothelium, are spanned by, diaphragms., The size of the filtration slits restricts the passage, of large molecules (eg, albumin) and cells (eg,, red blood cells and platelets). In addition, foot, processes have a negativelycharged coat, (glycocalyx) that limits the filtration of negatively, charged molecules, such as albumin., Between the visceral and parietal layers is, Bowman’s space, into which the filtrate enters, after passing through the podocytes’ filtration slits., Unlike the visceral layer, the parietal layer does, not function in filtration. Rather, the filtration, barrier is formed by three components: the, diaphragms of the filtration slits, the thick, glomerular basement membrane, and the glycocalyx, secreted by podocytes., The process of filtration of the blood in the, Bowman’s capsule is ultrafiltration (or, glomerular filtration), and the normal rate of, filtration is 125 ml/min., , Any protein under roughly 30 kilodaltons can, pass freely through the membrane, although there, is some extra hindrance for negatively charges, of the basement membrane and the podocytes., Any small molecules such as water, glucose,, salt (NaCl), amino acids, and urea pass freely, into Bowman’s space, but cells, platelets and, large proteins do not. As a result, the filtrate, leaving the Bowman’s capsule is very similar, to blood plasma in composition as it passes, into the proximal convoluted tubule., l, , l, , l, , l, , l, , l, , l, l, , l, , l, l, , The filtrate leaving the Bowmans capsule is very, similar to blood plasma in compostion as it passes, into the proximal convoluted tubule., Measuring the glomerular filtration rate (GFR), is a diagnostic test of kidney function. A decreased, GFR may be a sign of renal failure., The renal tubule functions as a dialysis unit, in, which the fluid inside the tubule is the internal, solution and the blood (in capillaries surrounding, the tubule) acts as the external solution., The renal tube consists of three parts: the, proximal convoluted tubule, the loop of Henle,, and the distal convoluted tubule., Proximal convoluted tubules (PCT) or pars, convoluta is about 14 mm long and lined by a, single layer of cubical cells., ‘Proximal’ means that it is near Bowman’s, capsule, and ‘convoluted’ describes its coiled, and looped shape., Cells of the proximal convoluted tubule have, numerous microvilli and mitochondria which, provide surface area and energy and closeness, of blood capillaries., Selective reabsorption occurs in the proximal, convoluted tubule., The loop of Henle (sometimes known as the, nephron loop) is a Ushaped tube that consists of, a descending limb and ascending limb., Loop of Henle begins in the cortex, receiving, filtrate from the proximal convoluted tubule,, extends into the medulla, and then returns to the, cortex to empty into the distal convoluted tubule, only in juxtamedullary nephrons. In other nephrons,, the loop merely extends through the kidneys cortex., Its primary role is to concentrate the salt in the, interstitium, the tissue surrounding the loop., The longer the nephron, the better it performs its
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 407, , ◄ŤĘŕĚŚŐŕť– ☼ťřŚĚŇ, , l, , l, l, , l, , l, , l, , l, , l, , l, l, , countercurrent exchange mechanism., Loop of Henle is short or absent in other, vertebrates like reptiles which cannot secrete, hyperosmotic urine., Descending limb are thin walled, lined by, squamous epithelium., Descending limb is permeable to water but, completely impermeable to salt, and thus only, indirectly contributes to the concentration of the, interstitium., Longer descending limbs allow more time for water, to flow out of the filtrate, so longer limbs make, the filtrate more hypertonic than shorter limbs., Ascending limb are thick walled formed by, cuboidal epithelium and impermeable to water., It actively reabsorbs the remaining 25% of the, filtered K+ and some amounts of Cl–, some Na+, , is also reabsorbed by diffusion due to electrostatic, attraction of reabsorbed Cl–., The ascending limb actively pumps sodium out of, the filtrate, generating the hypertonic, interstitium that drives countercurrent exchange., In passing through the ascending limb, the filtrate, grows hypotonic since it has lost much of its sodium, content. This hypotonic filtrate is passed to the, distal convoluted tubule in the renal cortex., The distal convoluted tubule (DCT), a portion, between the loop of Henle and the collecting duct, system, is partly responsible for the regulation, of potassium, sodium, calcium, and pH., The DCT regulates pH by absorbing bicarbonate, and secreting protons (H+) into the filtrate. Sodium, and potassium levels are controlled by secreting, K+ and absorbing Na+., Sodium absorption by the distal tubule is mediated, by the hormone aldosterone., The DCT also participates in calcium regulation, by absorbing Ca2+ in response to parathyroid, hormone., Histologically, cells of the DCT can be, differentiated from cells of the proximal, convoluted tubule :, – DCT cells do not have an apical brush border, – DCT cells are less eosinophilic than proximal, cells, – DCT cells have less cytoplasm, – DCT cells are more likely to have visible, nuclei, , l, l, l, , l, l, , l, , l, , l, , l, , l, , l, , Thiazide diuretics inhibit Na+/Cl reabsorption, from the DCT., DCT is lined by cuboidal epithelium without, brush border., The reabsorptive activity of the distal convoluted, tubule is under the influence of ADH, (vasopressin), which is one determinant of the, volume of urinary output., The collecting duct system begins in the renal, cortex and extends deep into the medulla., As the urine travels down the collecting duct system,, it passes by the medullary interstitium which has, a high sodium concentration as a result of the loop, of Henle’s countercurrent multiplier system., Though the collecting duct is normally impermeable, to water, it becomes permeable in the presence, of antidiuretic hormone (ADH)., The collecting ducts unite with each other in the, medulla to form still larger ducts of Bellini which, open into renal pelvis., The epithelium of the collecting ducts is made, up of principle cells (P cells) and intercalated, cells (I cells)., The P cells, which predominate are relatively tall, and have few organelles. They are involved in Na+, reabsorption., The I cells, which are present in smaller numbers, and also found in the distal tubules, have more, microvilli, cytoplasmic vesicles, and mitochondria., They are concerned with acid secretion and, HCO3– transport., Lower portions of the collecting duct are also, permeable to urea, allowing some of it to enter the, medulla of the kidney, thus maintaining its high ion, concentration (which is very important for the, nephron)., , URINE FORMATION, l, , l, l, l, , The formation of urine is the result of the following, process – ultra filtration or glomerular filtration, of the blood plasma by the glomeruli; selective, reabsorption by the tubules, and secretion by the, tubules., Glomerular filtration is the first of the three, processes that form urine., The molecules that leave the blood and enter the, glomerular capsule are called the glomerular filtrate., If the glomerular filtrate were excreted from the, body unchanged, persons would be in constant
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 408, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , danger of both dehydration and starvation., Glomerular filtration occurs because the pressure, of the blood flowing in the glomerular capillaries, is higher than the pressure of the filtrate in, Bowman’s capsule., Effective filtration pressure may be expressed as –, EFP = GCP – (GOP + CHP), where, EFP = effective or net filtration pressure; GCP, = glomerular capillary pressure; GOP = glomerular, osmotic pressure; CHP = capsular hydrostatic pressure., , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , Tubular reabsorption is the second process in, the formation of urine from filtrate. As a result, of tubular reabsorption, much of the filtrate passes, out of the nephron tubule and returns to the blood, through the peritubular capillaries., Reabsorption occurs within cell, three regions of, the nephron and in the collecting duct, but most, of it takes place within the proximal convoluted, tubule., Depending on the type of molecule being, reabsorbed, movement into and out of epithelial cells, occurs by passive transport or active transport., Water and urea, for example, are reabsorbed by, passive transport, by which they move from, regions of higher concentration to regions of lower, concentration., Water is reabsorbed by osmosis and urea by simple, diffusion. Water is reabsorbed in all parts of the, tubule except the ascending loop of Henle., Glucose and amino acids are reabsorbed by active, transport., The reabsorption of Na+ occurs by both passive, and active transport. Na + moves passively by, diffusion from the filtrate into tubule cells but is, actively transported out of the tubule cells on its, way to the peritubular capillaries., Renal threshold of a substance is its highest, concentration in the blood upto which it is totally, reabsorbed from the glomerular filtrate., High threshold substances are almost completely, absorbed from nephric filtrate, e.g., glucose, amino, acids, vitamin C, Na +, water. Glucose has a, threshold value of 180 mg/100 ml., Low threshold substances (in which only very small, reabsorption occurs) are urea, uric acid, xanthin,, phosphate and nonthreshold substances are not at, all reabsorbed, e.g., creatinine, hippuric acid., Certain chemicals in the blood that are not removed, by filtration from the glomerular capillaries are, , l, , l, l, , l, l, , l, , l, , l, l, , l, , l, , l, , l, , removed by a third process of urine formation called, tubular secretion., Ions removed from the blood by tubular secretion, include potassium (K+ ), hydrogen (H+ ) and, ammonium (NH4+ ) and foreign substances like, drugs, penicillin, uric acid, creatine etc., The secretion of H+ is an important way in which, kidneys help control blood pH., Water reabsorption is controlled by antidiuretic, hormone (ADH), secreted by posterior pituitary, gland, in negative feedback and aldosterone, hormone (secreted by adrenal cortex) regulates the, transfer of sodium from the nephron to the blood., ADH increases the reabsorption of water by the, distal tubule and collecting duct., Dehydration results in an increase in ADH, while, water sufficiency results in low ADH allowing, for diluted urine., The more ADH, the more permeable the ducts, the, more water reabsorbed; the less ADH, the less, permeable the ducts, the less water reabsorbed. This, is related to the high osmolarity of the, interstitium due to the countercurrent multiplier, system of the loops of Henle., Drugs called diuretics increase the production of, dilute urine and prevent the excessive water, retention and tissue swelling (oedema) that may, accompany congestive heart failure, high blood, pressure and other conditions., Alcohol inhibits the secretion of ADH, thus, increases water loss., Under the deficiency of ADH, a disease called, diabetes insipidus is caused in which the output, of urine may reach 340 litre/day in place of normal, 1.2–1.8 litre/day. Frequent urination and thirst is, the symptoms of the disease., Renin (secreted by the cells of afferent arteriole), initiates a series of chemical reactions that, ultimately result in aldosterone secretion from the, adrenal cortex, which acts primarily on the distal, convoluted tubule to promote absorption of, sodium and excretion of potassium., Renin acts in the following way : renin Þ adrenal, cortex Þ aldosterone Þ distal convoluted tubule Þ, reabsorption of sodium and excretion of potassium., The presence of too much blood in the circulatory, system stimulates the heart to produce atrial, natriuretic hormone (ANH)., This hormone inhibits the release of aldosterone
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 409, , ◄ŤĘŕĚŚŐŕť– ☼ťřŚĚŇ, , l, , l, l, l, , l, l, , l, l, l, l, l, , l, , l, , l, , l, , by the adrenal cortex and ADH by the posterior, pituitary causing the kidneys to excrete excess water., The hormone, erythropoietin, a circulating, glycoprotein is produced by interstitial cells in the, peritubular capillary bed of the kidney., Erythropoietin is concerned with the regulation, of normal erythropoiesis., In the kidneys primary prostaglandins causes an, increase in renal blood flow and vasodilation., Kininogen produced by the kidneys has an, antihypertensive effect and regulates blood, pressure., Kidneys play an important role in vitamin D, metabolism., Micturition is the act of emptying the bladder or, passing urine. The total volume of urine (approx., 1.5 lt) in 24 hours is much less than the amount of, glomerular filtration (approx. 170 lt)., Urine is transparent, amber coloured, hypertonic, fluid with a slightly acidic pH (average 6.0)., The yellow colour of the urine is caused by the, pigment urochrome., Least concentration of urea is found in renal vein., Highest concentration of urea is found in hepatic, vein., Kidney transplantation or renal transplantation, is the organ transplant of a kidney in a patient with, chronic renal failure or some renal tumors., Renal failure or kidney failure is the loss of the, kidneys’ ability to excrete wastes, concentrate urine,, and conserve electrolytes, means a condition, where the kidneys fail to function properly., The first successful kidney transplantations were, done in 1954 in Boston and Paris. The, transplantation was done between identical twins,, to eliminate any problems of an immune reaction., It was actually the first successful human organ, transplant in history., The artificial kidney uses the principle of dialysis, to purify the blood of patients whose own kidneys, have failed., Dialysis is a method of removing toxic substances, (impurities or wastes) from the blood when the, kidneys are unable to do so., , l, , In haemodialysis (also known as artificial kidney), the patient’s blood is passed through a tube to a, semipermeable membrane (dialyzer) that filters out, waste products. The cleaned blood is then returned, back to the body. The procedure is monitored by, a machine, which also provides the dialysis fluid,, mixing it from a concentrate and water., , DISORDERS, l, , l, , l, l, , l, l, l, l, l, l, l, , l, l, , l, l, , Albuminuria is presence of albumin in urine and, it occurs when the filtering pores enlarge in size (it, is the indication of increase in glomerular, permeability)., Nephritis or Brights disease infection is caused, by bacteria (Streptococci) which results in, inflammation of kidney that involves glomerulus., Pyelonephritis is inflammation of the tissue of, kidneys and the ureters in the pelvic region., Renal stone is formation of calculi (large stones), in the kidney due to dehydration, excess uric acid, formation, excess calcium intake etc., Polyuria occurs when excess amount of dilute, urine is passed out as in diabetes insipidus., Uraemia is the increased concentration of urea in, blood., Alkaptonuria is a genetic disease in which, homogentisic acid is excreted out with urine., Pyuria is presence of pus in the urine., Glycosuria is presence of glucose in urine due to, diabetes., Haematuria is presence of blood in the urine., Anuria is the failure of kidney to form urine., Ketosis is the presence of ketones or acetone bodies, in urine due to metabolism of fatty acids instead of, glucose during diabetes, starvation and pregnancy., Acetone bodies are acetoacetic acid, beta, hydroxybutyric acid and acetone., Cystitis is the inflammation of urinary bladder,, caused by bacteria. It is more common in female, due to short urethra., Gout is high level of uric acid in blood., Dysuria is painful urination. Diuresis is a, condition in which the excretion volume of urine, is increased.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 410, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 43, , Nervous System, l, , l, l, l, , l, l, , l, l, l, l, l, l, , l, , Nervous system is a system of neurons, nerves, and nervous organs that coordinate and control the, activities of different parts of animal body by, sending and receiving nerve impulses., Study of morphology, physiology and pathology of, nervous system is called neurology., The nervous system is the body’s information,, gatherer, storage centre and control system., The nervous system –, –, Gathers information both from the outside, the body (called sensory function), –, Transmits the information to the processing, area of the brain and spinal cord, –, Processes the information to determine the, best response (called integrative function), –, Sends information to muscles glands and, organs (effectors) so they can respond, correctly (called motor function)., In humans the cells called neurons make up the, nervous system., Neurons allow messages to be carried from one, cell to another so that communication among all, body parts is smooth and efficient., Neuron is the basic functional and structural unit, of the nervous system., A neuron carries impulse in only one direction., A neuron has three parts : cell body/cyton,, dendron and axon., Extending from the nerve cell body several fine, cytoplasmic threads called dendrites are present., One of these very long dendrites is called axon., Axon is covered by a myelin sheath, which again, is covered by a membrane called neurolemma or, Schwann sheath., [For more on neurons refer chapter Animal tissue], Minimum power of regeneration is found in, nervous system., , l, , l, , l, , l, l, , l, , l, l, , l, l, l, l, , The nervous system is divided into two major, division : the central nervous system and the, peripheral nervous system., Central nervous system consists of brain and, spinal cord whereas the peripheral nervous, system consists of neurons not included in the brain, and spinal cord., Some peripheral neurons collect information from, the body and transmit towards the CNS (called, afferent neurons) and other peripheral neurons, transmit information away from the CNS (called, efferent neurons)., The motor or efferent neurons is further divided, into somatic and autonomic nervous system., The somatic nervous system is the voluntary part, of nervous system that coordinates a body’s, movement such as maintaining a particular posture, and walking., The autonomic nervous system is the involuntary, part which seems to be concerned with striking a, balance or maintanining homeostasis in the, functioning of many organs of the body., The central nervous system serves as the control, centre of the body., The central nervous system relays messages,, processes information and compares and analyzes, information., CNS is dorsal, hollow and non ganglionated in all, the vertebrates including man., Central nervous system is composed of two main, organs i.e., brain and spinal cord., Two types of matter is present in central nervous, system, these are grey matter and white matter., Grey matter is formed of cell bodies and non, medullated nerve fibres and can be found on the, surface of cortex as well as in clusters called nuclei, deep within the brain.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 411, , ░ĚŕŢŐśř– ☼ťřŚĚŇ–, l, , White matter refers to axons and their surrounding, myelin insulation which gives this its white colour., White matter is found in bundles of fibres known, as tracts which connects the different parts of the, brain., , l, , l, , Brain, l, , l, , l, , Brain (also called encephalon) is the widest and, uppermost part of CNS which lies protected, (against mechanical injury and shock) inside the, cranial cavity of skull and controls all activities, of nervous system., Brain is surrounded by 3 meninges (dura, pia and, arachnoid) in rabbit, man and other mammals,, which separates the skull from the brain; while 2, meninges in frog (dura and piamater)., Meninges are connective tissue membranes which, protect the CNS and projection of its structure and, separate the brain and spinal cord from the skull, and vertebrae., , l, l, l, l, l, l, , Piamater is the innermost and duramater is the, outermost meninges. Arachnoid is present in, between piamater and duramater., The dura and arachnoid are separated by a, subdural space; the arachnoid and pia mater, are separated by the subarachnoid space., Between the meninges arachnoid and piamater, cerebrospinal fluid is present., Piamater is highly vascularised and nutritive., Arachnoid is porous and serous membrane and is, made up of reticular connective tissue., Duramater is double layered, thick and tough, nonvascular meninx., The dura mater, consists of an outer periosteal layer, and an inner meningeal layer., Within the vertebral canal, the periosteal layer of the, dura is absent. The meningeal layer forms a dural, sheath around the spinal cord; between the sheath, and surrounding bone lies the epidural space., , Table : Ventricle system of the brain., Structure, , Description, , Significance, , Ventricle,, lateral, , paired spaces within cerebral hemispheres, , they drain cerebrospinal fluid to the third ventricle, via the interventricular foramina (of Monro), , Ventricle,, third, , midline space within the diencephalon between, the paired dorsal thalami and the hypothalamus, , communicates posterolaterally with paired lateral, ventricles via interventricular foramina,, communicates posteroinferiorly with fourth, ventricle via cerebral aqueduct, , Ventricle,, fourth, , midline space between cerebellum posteriorly, and pons and upper medulla anteriorly, , communicates anterosuperiorly with third ventricle, via cerebral aqueduct; drains CSF via median, aperture and lateral apertures, , Choroid plexus, , vascular membranes that occur within the, ventricles, , production of cerebrospinal fluid, , Interventricu, lar foramen, , communication between the lateral ventricle, and the third ventricle; paired, one on each side, , also known as foramina of Monro, , Cerebral, aqueduct, , canal connecting third and fourth ventricles,, passing through midbrain, , also known as aqueduct of Sylvius (iter), , Median, aperture, , midline, irregular foramen draining fourth, ventricle, posteroinferiorly, into, cerebellomedullary cisternae, , also known as foramen of Magendie, , Lateral, aperture, , paired foramina draining fourth ventricle, laterally into cerebellomedullary cisternae, , also known as foramina of Luschka, , Central canal, of spinal cord, , small opening in the centre of the spinal cord, , continuous with the central canal of the medulla, and, through it, with the fourth ventricle of the brain
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, , l, l, , l, , l, , l, l, , l, l, , l, , l, , l, l, , l, , Duramater is protective in function., The brain has four internal chambers called, ventricles (Refer table on page no.412). Each, cerebral hemisphere houses a large lateral, ventricle that communicates with a third, ventricle through an interventricular foramen., The cerebral aqueduct connects the third with, the fourth ventricle., A choroid plexus within each ventricle produces, cerebrospinal fluid (CSF)., Cerebrospinal fluid, secreted by anterior choroid, plexus and posterior choroid plexus, fills four, interconnected ventricles, or cavities in the brain., Within the ventricles, cerebrospinal fluid acts as a, transport medium for substances that are, important to brain function., The cerebrospinal fluid, is a blood filtrate which, is colourless, clear and slightly alkaline (7.33, pH) fluid that protects the brain from mechanical, injury by acting as a shock absorber., CSF also maintains a constant pressure inside, the cranium inspite of variation in the pressure of, blood in the cranial vessels., CSF lends buoyancy, protects, removes wastes,, and provides a stable chemical environment., CSF circulates throughout the ventricles, and makes, its way into the central canal of the spinal cord. It, exists the fourth ventricle through two apertures, and enters the subarachnoid space., Increase in cerebrospinal fluid may results in, meningitis., The CNS is protected by a bloodbrain barrier, that regulates substances entering the brain., Tight junctions within capillaries and astrocytes, comprise this barrier., The bloodbrain barrier is absent in areas of the, brain (called circumventricular organs) that, monitor blood glucose, pH, salinity, and so forth., Brain is the main switching unit of the central, nervous system. It is the place to which impulses, flows and from which impulse originate., The brain is primarily made up of two types of, cells: glia and neurons., Glia function primarily to support and protect the, neurons. The neurons carry information in the form, of electrical impulses known as action potentials., They communicate with other neurons in the brain, and throughout the body by sending various, chemicals called neurotransmitters across gaps, , l, l, , l, , l, , l, l, l, , known as synapses., The brain is protected by a bony covering called, the skull., If the oxygen supply to the brain is cut off even for, a few minutes, the brain will usually suffer enormous, damage. Such damage may result in death., Brain is made of three main parts : fore brain, (also called prosencephalon); mid brain (also called, mesencephalon); hind brain (also called, rhombencephalon) which continues into spinal, cord., Fore brain occupies anterior two third of brain, and is formed of the following three parts :, olfactory lobes (rhinencephalon), cerebral, hemisphere (telencephalon) and diencephalon., Olfactory lobes control the smell. These are small, sized in man., 80% of the weight of brain is formed of cerebral, hemisphere., Two cerebral hemisphere are collectively, called cerebrum but are demarcated by cerebral, Not well developed in man, Cerebrum (Telencephalon), l Contains lateral ventricles, l Consists of 2 cerebral, hemisphere, l Largest part of brain., , Fore, brain, , Consists of three parts, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , BRAIN, , 412, , Epithalamus, (roof), , Thalamus, (sides), l, , Mid, brain, , l, , Hypothalamus, (floors), , Contains cerebral peduncles, and corpora quadrigemina, (reflex centre of eye movements, and auditory responses., Tectum is the collective term for, auditory and optic lobes., , Cerebellum, , Hind, brain, , l, l, , Consists of 2 hemisphere, and a vermis., Arbor vitae is present, , Pons varolii, l, , Acts as bridge carrying, ascending and descending, tracts between brain and, spinal cord, , Medulla oblongata, l, , Contains IVth ventr icle, (called metacoel), , Flow chart : Brain and its parts
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░ĚŕŢŐśř– ☼ťřŚĚŇ, , l, l, l, l, , l, , l, l, , l, l, l, , l, , fissure., Thick dorsal wall of cerebrum is called pallium, and the ventrolateral walls is called corpora striata., The ridges and depressions in the roof of cerebral, hemisphere is called gyri and sulci respectively., The gyri increases the surface area of the cortex., The increased surface area permits the large, numbers of neurons to fit easily within the confines, of the skull., The whitish nervous band by which two cerebral, hemispheres are interconnected is called corpus, callosum., Corpus callosum participates in the formation of, 5th ventricle or pseudocoel., The grey matter of cerebral hemisphere is called, cerebral cortex and deeper white matter is called, cerebral medulla., Centre of highest sensation and activities is, cerebral cortex., Cerebrum is the most prominent and the largest, part of the human brain., Each cerebral hemisphere is divided into four regions, called lobes. These are frontal at the front, parietal, towards the top of the head, temporal on the side, and occipital at the rear (Refer table given below)., Diencephalon contains epithalamus, thalamus, and hypothalamus., Table : Functional areas of cerebrum., Area, , Location, , l, l, , l, , l, l, , l, l, , l, , Function, , 1. Premotor area Frontal lobe, , The highest centre for, involu ntary, movements, of, muscles and ANS, , 2. Motor area, , Frontal lobe, , Controls voluntary, movements of the, muscle, , 3. Broca’s area, , Frontal lobe, , Motor speech area, , 4. Som est h et ic Parietal lobe, area, , l, , Perception of general, sensation like pain,, touch, and, temperature, , 5. Gustatory area Parietal lobe, Sense of taste, 6. Auditory area Temporal lobe Hearing, , l, l, , l, , l, , 7. Olfactory area Temporal lobe Sense of smell, 8. We r n i c k e ’ s Temporal lobe U n d e r s t a n d i n g, area, speech, 9. Visual area, Occipital lobe Sensation of light, , l, l, , 413, , Diencephalon lies between cerebrum and, mesencephalon. Its cavity is called third ventricle, or diocoel., Epithalamus is nonnervous part which is fused, with piamater to form anterior choroid plexus., The thalamus and hypothalamus are found in the, part of the brain between the brain stem and, cerebrum., The thalamus, which is composed of grey matter,, serves as a switching station for sensory input, including sound and balance. With the exception, of smell, each sense channels its sensory nerves, through the thalamus., Thalamus forms the roof of third ventricle., Immediately below the thalamus is the, hypothalamus, which is the control centre for, hunger, thirst, fatigue, anger and body, temperature., The hypothalamus forms the floor and the part, of the lateral walls of the third ventricle., The hypothalamus acts like a ‘thermostat’ by, sensing changes in body temperature and then, sending signals to adjust the temperature. For e.g., if one is feeling hot, the hypothalamus detects this, and then sends a signal to expand the capillaries in, skin. This causes heat loss., Hypothalamus links nervous system to, endocrine system (via hypothalamus hypophyseal, axis) and exercises a regulatory control on the, functioning of endocrine glands by secreting, neurohormones. It synthesises the posterior, pituitary hormones and control their release into, the blood., Hypothalamus is partially protected by the sella, turcica of the sphenoid bone., Parts of the diencephalon and the cerebrum are, included in an important group of connected brain, centres called the limbic system., The limbic system includes the thalamus, the, hypothalamus, some deeper parts of the cerebral, cortex, and centres in the temporal lobes., The limbic system plays an important role in, emotions, memory, and motivation, among other, things., Midbrain is formed of optic lobes and cerebral, peduncles., In rabbit, man and mammals 4 solid optic
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 414, , l, l, l, l, , l, , l, l, , l, l, l, l, , l, , l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , lobes are present. These are known as quadrigemina., Midbrain controls muscle tone and some motor, activities., Cerebellum, medulla oblongata and pons varolli, are the three parts of hind brain., Cerebellum is also called little brain., The cerebellum is similar to the cerebrum in that, it has two hemispheres and has a highly folded, surface or cortex. Cerebellum is associated with, regulation and coordination of movement,, posture, and balance., Sections of cerebellum shows branching radiation, of white matter into grey matter, called as, arbor vitae., The cerebellum is the second largest part of the, brain, and is located at the back of the skull., The cerebellum receives sensory impulses from, muscles, tendons, joints, eyes and ears as well as, input from other brain centres., The left side of the brain controls the right side of, the body and vice versa., Medulla oblongata (myelencephalon) is the, posterior most part of the brain., The cavity of medulla oblongata is known as, IVth ventricle or metacoel., Medulla oblongata controls involuntary functions, like, heart beat, rate of respiration, secretion of, glands, vomiting, coughing etc., Another important part of the medulla is group of, cells known as the reticular activating system or, reticular formation (RAS)., The reticular activation system (RAS) actually helps, to alert, or awaken, the upper parts of the brain,, including the cerebral cortex., The RAS also helps to control respiration and, circulation and serves as a filtering system for, incoming sensory signals., In medulla oblongata and pons varolli, grey matter, is internal and white matter is external while the, arrangement is reverse in other parts of brain., Pons varolli is situated in front of the cerebellum, below the mid brain and above the medulla, oblongata., It carries impulse from one hemisphere of the, cerebellum to another., Functionally, the pons is concerned with, maintenance of normal rhythm of respiration., , l, l, , l, , It has got two respiratory centres the, pneumotaxic centre and apneustic centre. It is, also related with the control of facial expression,, movement of the eyeball, micturation etc., The brain stem connects the brain to the spinal, cord., The brain stem, which maintains life support, system, consist of the diencephalon, medulla, oblongata, pons varolii and the midbrain., The brain stem not only coordinates and, integrates all incoming information; it also serves, as the place of entry or exit for ten of the twelve, cranial nerves., , Spinal cord, l, l, l, l, l, l, l, l, l, l, , l, , l, l, , Spinal cord provides the link between the brain, and rest of the body., Spinal cord is about 45 cm long and about 35 gm, in weight., Spinal cord is divided into two by dorsal septum, and ventral fissure., The arrangement of white matter and grey matter, in spinal cord is same as in medulla oblongata., In spinal cord, white matter is found outside the, grey matter (reverse in brain)., Spinal cord coordinate and control those reflex, responses which occur without brain., Spinal cord is present in neural canal of vertebrates., Spinal cord in rabbit extends upto 4th lumbar, vertebra., Filum terminale is the terminal nonnervous part, (made of only piamater) of spinal cord., Cauda equina (horsetail) is the taillike collection, of roots of spinal nerves at the posterior end of, spinal cord., The cavity of spinal cord is known as central canal, or neurocoel which is lined with ciliated, ependymal epithelium., Grey matter surrounding central canal is Hshaped, or butterflyshaped., Spinal cord conduct impulses to and from the brain, and controls most of the reflex activities and, provides a means of communication between, spinal nerves and the brain., , Peripheral nervous system, l, , All nerves connecting the central nervous system, with receptors and effectors (muscles and glands), constitute the peripheral nervous system (PNS).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░ĚŕŢŐśř– ☼ťřŚĚŇ–, l, l, l, , l, l, l, , l, l, l, l, l, , l, l, , l, , l, , Cranial nerves and spinal nerves are the main, constituents of PNS., 12 pairs of cranial nerves are present in amniotes, and 10 pairs in anamniotes., Twelve pair of cranial nerves are – (I) olfactory,, (II) optic, (III) oculomotor, (IV) trochlear,, (V) trigeminal, (VI) abducens, (VII) facial,, (VIII) auditory, (IX) glossopharyngeal, (X) vagus,, (XI) spinal accessory and (XII) hypoglossal., There are 3 pair of sensory, 5 pair of motor and, 4 pair of mixed cranial nerves., Spinal accessory and hypoglossal are the two, nerves present in man but absent in frog., Trochlear is the smallest cranial nerve and the, only nerve that exists the posterior side of the, brain stem., The largest cranial nerve is trigeminal, (mandibular branch)., Vagus is the longest cranial nerve. It has maximum, branches and also called wandering nerve., Vagus supplies the regions other than head., Spinal nerve is a mixed nerve., When the motor and sensory fibres exit the spinal, column through the intervertebral foramina and pass, through the meninges, they join together to form, the spinal nerves., 31 pair of spinal nerves are present in human., There are 8 cervical (C1C8), 12 thoracics, (T1T12), 5 lumbar (L1L5), 5 sacral (S1S5),, and 1 coccygeal nerve., The spinal nerves provide innervation to body areas, below the neck while cranial nerves (also second, order neurons) carry impulses only to the head and, neck, except for the vagus., The spinal formula of spinal nerve in man is, C8Th12L5S5Co1., , Autonomic nervous system, l, , l, , Autonomic nervous system (ANS) is a system of, peripheral nerves and ganglion which innervates, various organs & glands to stimulate, accelerate,, slow down or inhibit their function without directly, consulting the will., The ANS has three main components –, –, Preganglionic nerve fibres. These are motor, nerve fibres, which emerge from CNS and, pass to autonomic ganglia., –, Autonomic ganglia. These are swollen, , l, , l, , l, l, , l, l, , l, l, , l, , l, , l, , l, , l, , 415, , bulbous structures containing the cell bodies, of many neurons., –, Postganglionic nerve fibres. These are axons, of neurons emerging from the autonomic, ganglia and supply smooth muscles and, glands., Autonomous nervous system is regulated by centres, in brain like cerebral cortex, hypothalamus and, medulla oblongata., ANS is concerned with heart rate, breathing rate,, blood pressure, body temperature and other, visceral activities that work together to maintain, homeostasis., Autonomic nervous system was explained and, coined by Langley (1921)., ANS, also called visceral efferent nervous, system, is made of two opposing divisions–, sympathetic and parasympathetic., Sympathetic nervous system is also called, thoracicolumbar outflow., Sympathetic nervous system is represented by a, chain of 21 sympathetic ganglia on either side of, spinal cord. It receives preganglionic sympathetic, fibres from the spinal cord which make their exit, alongwith thoracic and lumbar nerves., It is active in stress condition, pain, fear and anger., The postganglionic sympathetic fibres are mostly, adrenergic i.e., they release neurotransmitter, noradrenaline at their terminations. However, pre, ganglionic sympathetic fibres are cholinergic i.e.,, liberate acetylcholine at their endings., Action of sympathetic system results in accelerated, heart rate, increased blood pressure and blood, flow away from the periphery and digestive system, toward the brain, heart and skeletal muscles. It also, causes adrenaline to be released, temporarily, increasing physical strength., The sympathetic nervous system is an involuntary, system often associated with the flight or fight, response., Parasympathetic nervous system consists of, preganglionic parasympathetic fibres, para, sympathetic ganglia and postganglionic, parasympathetic fibres., Preganglionic parasympathetic fibres make their, exit along with the 3rd, 7th, 9th and 10th cranial, nerves, and 2nd, 3rd, 4th sacral nerves., Parasympathetic ANS is also called cranio sacral
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 416, , l, , l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , outflow., The parasympathetic system brings the body back, to a state of equilibrium. It slows heart rate and, decreases the release of hormones into the blood, stream., Parasympathetic provides relaxation, comfort,, pleasure at the time of rest. It helps in the, restoration and conservation of energy., Preganglionic nerve fibre of sympathetic ANS is, small sized whereas that of parasympathetic ANS, is larger., Postganglionic nerve fibres of sympathetic ANS, involve expenditure of energy but postganglionic, never fibre of parasympathetic ANS involve, conservation of energy., Action of sympathetic and para sympathetic ANS, is antagonistic to each other but neither exclusively, excitatory nor inhibitory., Sympathetic nerves stimulate the adrenal glands to, secrete adrenaline., Both of the pre and postganglionic parasympathetic, fibres are cholinergic i.e., they release acetylcholine, at their endings for the transmission of nerve impulses., , l, l, l, , l, , l, , l, l, l, , l, , Nerve impulse, l, , l, l, l, , l, , l, , l, , Nerve impulse is a wave of bioelectric disturbance, that passes along a neuron during conduction of an, excitation., The mineral necessary for nervous conduction, is sodium and potassium., Nature of nerve impulse or conduction of nerve, impulse is an electrochemical process., Impulse conduction depends upon permeability, of axon membrane (axolemma) and osmotic, equilibrium and electrical equivalence between, the axoplasm and extracellular fluid (ECF), present outside the axon., Nerve impulse is marked by the flow of ions, across the membrane of the axon caused by, changes in the permeability of the membrane,, producing a reduction in potential difference that, can be directed as the action potential., The electrochemical potential developed during, depolarisation is called action potential/reverse, potential/reverse polarisation. Its value is, 20 – 30mV(+), occasionally + 60mV., During the conduction of nerve impulse along the, nerve fibres (called transmission of impulse), the, , l, l, l, , l, , l, l, , action potential is the result of movement of Na+, from extracellular fluid to intracellular fluid., Change in potential due to stimulation of nerve, fibre is called nerve potential., The strength of the impulse produced in any nerve, fibre is constant., In resting state the neuron membrane is polarised, with outer surface + vely charged and inner, surface – vely charged., The resting membrane potential is about –40 mV, to –90 mV with an average of –70 mV (1 mV or, milli volt = 1/1000 volt)., The threshold stimulus for opening of Na +, channels is generally –55 to –60 mV (about 10 mV, less than resting potential)., Threshold or firing level is the minimum strength, to initiate action potential., The time for restoration of nerve fibres is called, refractory period. It is about 0.001 sec., Transmission of nerve impulse occurs in three, stages – polarised state, depolarised stage and, repolarised stage., Resting condition of the nerve is called polarized, nerve., At polarized nerve Na+ is 1012 times more outside, than inside of a nerve., In depolarized nerve Na+ enters inside and thus, +ve charge is formed inside and ve outside., After conduction of impulse resetting of membrane, potential takes place and charges arrange as in, polarised nerve. It is called repolarised nerve., Movement of Na+ from inner side to outer side is, called sodium pump and that of potassium from, outer to inner side is called potassium pump., Speed of nerve impulse in more (about 20 times faster), in myelinated nerve than in unmyelinated fibre., In myelinated nerve fibres the exchange of ions, take place only at the node of Ranvier. This, jumping conduction of action potential from node, to node is called saltatory conduction., Saltatory conduction occurs because the voltage, gated sodium ion channels are found only at the, nodes of Ranvier and between the nodes the myelin, sheath acts as a good electrical insulation. It leads, to conduction speed upto 120 m/s and is, responsible for the high speed impulse, transmission.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░ĚŕŢŐśř– ☼ťřŚĚŇ–, l, l, , l, , l, , l, l, l, l, l, , l, , l, , l, , l, , l, , l, , Saltatory propagation increases the speed of nerve, impulse., Velocity of nerve impulse depends on myelination, as well as diameter of the fibre. It is slower in, thinner fibre than in thicker fibre., Nerve terminates in 3 different ways – on the, receptor; on the next neuron and make synapse and, on the surface of muscles and make motor end, plate., A synapse is in the close proximity of end knob, of one neuron and dendron or cell body of next, neuron., Term synapse was coined by Sir Charles, Sherrington., Nerve impulse through synapse is unidirectional., The process of chemical transmission across, synapse was discovered by Henry Dale (1963)., The chemical causing the transmission of the nerve, impulse across synapse/ end plate is acetylcholine., Synapse comprises of a synaptic cleft between the, end of one nerve fibre and the beginning of the, next. The presynaptic neuron forms terminal, swellings called synaptic knobs, on the post, synaptic neuron., The synaptic knob contains numerous synaptic, vesicles, which contain the neurotransmitter, acetylcholine., Acetylcholine is formed in the cell body with the, help of a special enzyme, choline acetylase and then, transported down the axon to the presynaptic, terminals., The arrival of an impulse at the synaptic knob, causes acetylcholine to be discharged into the, synaptic cleft., Accumulation of acetylcholine in the synaptic cleft, reduces the polarization of dendrites, or cell body, of the next neuron. If depolarization is sufficient, the threshold of the next neurons will be reached, and a nerve impulse generated in it., With each passing nerve impulse, the concentration, of acetylcholine becomes highly concentrated in the, synaptic cleft and diffuses in all directions., An enzyme, acetylcholinesterase is present to break, down the acetylcholine (to choline and acetate),, preventing continued depolarization of the next, fibre or the inordinate (exceeding normal limits), spreading of the nerve impulse to other nerve fibres., , l, , 417, , In a synapse the propagation is strictly one way, proceeding from axon of one neuron to the soma,, or dendron of another neuron., Since dendrites do not release any chemical, neurotansmitter so, any nerve impulse passing, along a single neuron from axon to dendrites, would fade out as the synapse. Hence the, synapse acts as a valve permitting only one, way traffic of nerve impulse., , l, , l, , l, , l, l, , Neuromuscular junction is a specialised form of, synapse which is found between a motor neuron, and skeletal muscle fibre. Each muscle fibre has, a specialised region called motor end plate which, contains vesicles and mitochondria. When the motor, impulse from the nerve is received on the motor, end plates, a local depolarization occurs thereby, resulting in the excitation of the muscle fibre. They, always use the neurotransmitter acetylcholine, and are always excitatory., Neurotransmitter may be excitatory (depolarizing, postsynaptic membrane) or inhibitory, (hyperpolarizing postsynaptic membrane)., Examples of excitatory neurotransmitter are , acetylcholine, norepinephrine, serotonin, dopamine,, histamine, glutamate and 5 hydroxytryptamine etc., Examples of inhibitory neurotransmitter are, glycine and GABA (Gamma amino butyric acid)., Neuromodulators are additional neurotransmitters,, that are released and modify the transmission of, an impulse at a synapse, either prolonging or, inhibiting it and are responsible for mood and, emotion in the brain., Addictive drugs, such as cocaine, often act as, neuromodulators. The brain adjusts its synapses, to accommodate such drugs, and the result is, physiological dependence, or addiction., , l, , l, l, , Neurotransmitter is a chemical that transmits, information across the junction (synapse) that, separates one nerve cell (neuron) from another nerve, cell or a muscle., Neurotransmitters are stored in the nerve cell’s, bulbous end (axon)., Neurotransmitters transmit information within the, brain and from the brain to all the parts of the body., Acetylcholine, for example, sends messages to the, skeletal muscles, sweat glands, and heart; serotonin
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 418, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , release underlies the process of learning and, consciousness., Abnormalities in the production or functioning of, certain neurotransmitters have been implicated in, a number of diseases including Parkinson’s, disease, amyotrophic lateral sclerosis, and, clinical depression., Synaptic fatigue is due to exhaustion of, neurotransmitter., Cybernetics deals with neural and chemical, integration of the body., , Reflex action, l, , l, , l, , l, l, , l, , l, , l, , l, , Reflex action (Marshal Hall, 1833) is the, spontaneous, automatic mechanical response, produced by stimulating specific receptors., A reflex action or reflex is a biological control, system linking stimulus to response and mediated, by a reflex arc. Reflexes can be builtin or learned., Reflex arc is the arrangement of neurons in the, pathway that always pass through central nervous, system., Reflex arc is formed by receptor spinal cord, effector (muscle or gland)., Reflex arc may be monosynaptic (sensory and, motor neurons) or polysynaptic (sensory,, association or internuncial or interneurons and, motor neurons)., Reflex action is of two types: conditioned, (acquired) and unconditioned (simple) reflex, action., Unconditioned or inborn reflexes can be evoked, even immediately after birth and do not need, previous experience, e.g breast feeding, constriction, of eye pupil of a new born in bright light., Conditioned/acquired reflexes are those reflex, actions that are not present at birth but develop, later in life through learning, habit, experience, or regular association of an indifferent stimulus, (without any effect) with unconditioned, stimulus., , l, , l, , l, , brain, e.g., pedalling, driving a vehicle, playing, musical instrument, writing, reading, daily chores,, knitting without looking, salivation at sight or smell, of food., Conditioned reflex was first demonstrated by I.P., Pavlov., Pavlov (1906) found that a dog salivated at the sight, of food. He would sound a gong every time the dog, was given food. After some days, the dog would, salivate on hearing the bell even without food., Examples of simple reflex are –, –, Knee jerk (stress reflex) – tendon of patella, tapped., –, Corneal reflex (Blinking reflex) – closing of, eyelids., –, Rapid withdrawal of hand while burned or, pricked., –, Quick recovery of balance while falling., –, Scratch reflex of frog – in pithed frog with, acetic acid., –, Coughing, sneezing and yawning –, , Disorders of nervous system, l, , l, , l, , Conditioned reflexes are liable to change,, disappear or reappear. They reduce burden on, l, l, , Stroke is a condition due to the lack of oxygen to, the brain which may lead to reversible or irreversible, damage. The damage to a group of nerve cells in, the brain is often due to interrupted blood flow,, caused by a blood clots or blood vessel bursting., Depending on the area of the brain that is damaged,, a stroke can cause coma, paralysis, speech problems, and dementia., Hydrocephaly is an increased quantity of, cerebrospinal fluid (CSF) inside the brain that can, result in increased pressure. Often the result of a, disturbance (obstruction) in the normal CSF, circulation or the overproduction of CSF., Meningitis refers to infection or inflammation of, meninges resulting in severe headache, vomiting, and pain, and stiffness of the neck. Cause of, meningitis is the infection of bacteria viz., Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae., Encephalitis is the inflammation of the brain. Its, symptoms include lethargy (fatigue), and drowsiness., Epilepsy happens when electrical activity in the, brain is not normal.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ĚňřĚ– ▒ŕĹďňř, , 419, , Chapter 44, , Sense Organs, l, , l, , l, , l, , l, , l, l, l, l, , l, , l, , Sense organs is a part of the body of an animal, that contains or consists of a concentration of, receptors that are sensitive to specific stimuli., Stimuli include pressure, temperature, chemical, substances, vibrations, mechanical deformation, and radiant energy., Receptors may act directly by opening ion, channels in the cell membrane that are part of the, same receptor molecule or indirectly by, inactivating second messenger system that go on, to affect various processes in the cell., Stimulation of these receptors initiates the, transmission of nervous impulses to the brain, where, sensory information is analysed and interpreted., The sense of touch/pressure/pain is called general, sense as its receptor cells lie scattered in the skin, & various body parts., On the basis of their location receptors may be, interoceptors, proprioceptors, exteroreceptors., Interoceptors or visceroceptors receive internal, stimuli like hunger, thirst etc., The interoceptors are simple and mostly consists, of free nerve endings., Proprioceptors are sensitive to changes in, tendons, muscles & joint movements. They provide, the information about the orientation of the body, in space and the position of the limbs., Exteroreceptors are somatic receptors located at or, close to the body surface to receive external stimuli., Eg. cutaneous receptors & special sense organ., According to type of stimuli receptors may be, mechanoreceptors (mechanical stimuli), chemoreceptors (sensitive to chemicals or their, concentration); photoreceptors (sensitive to, intensity & wavelength of light, image, formation, eg., rods, cones & ommatidia); and, thermoreceptors (sensitive to temperature)., , l, , l, l, l, l, , l, , l, l, l, , Thermoreceptors are of two types – caloreceptors, (sensitive to heat, eg. Ruffini’s organs) and, frigidoreceptors (sensitive to cold, eg. end bulbs, of krause)., Ampulla of Lorenzini is a type of thermoreceptors, in scoliodon., Chemoreceptors includes taste and smell., Skin receptors are broadly divisible into twotypes : free, nerve endings & encapsulated nerve endings., Functionally skin receptor are of the following, types– algesireceptor (pain); tactile or, tangoreceptors (touch); thermoreceptors, (temperature changes) and vibroreceptors, (vibrations)., According to their shape & distribution, types of, tangoreceptors are –, –, Merkels disc [epidermis of hairless skin, (glabrous)]., –, Meissner’s corpuscles (dermis of skin of, finger tip; lips & nipples, sensitive to touch, & gentle pressure)., –, Pacinian corpuscles (present in subcutaneous, tissue of palm, soles of fingers, etc. stimulated, by pressure contact)., –, Corpuscles of Mazzoni (subcutaneous tissue, of fingers, sensitive to heavy touch, pressure,, joint, rotation)., –, Free nerve endings (present on skin, perceive, the sensation of touch, pressure and pain)., –, Hair and organ (sensitive to touch &, movement of objects)., Tactile receptors in mammals are maximum on, the face., Rheoreceptors detect water current like lateral line, sense organ in fishes & amphibian tadpoles., Nociceptors are sensitive to deep pain & damage, to tissue.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 420, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Phonoreceptors are sensitive to sound, eg. organ, of Corti., Statoreceptors are equilibrium receptors, eg. cristae, & maculae., The main human sense organs are –, –, The eye which detects light and colour, (different wavelengths of light), –, The ear which detects sound (vibrations of, the air) and gravity, –, The nose which detects some of the chemical, molecules in the air, –, The tongue which detects some of the, chemicals in food, giving a sense of taste., , ORGAN OF SIGHT EYE, l, l, l, , l, , l, , l, , l, l, l, , l, l, l, , l, l, , Eyes are sense organ for sight (vision)., It is spherical in shape and is located in the orbit, oblong socket of the skull., Movement of eyeball in the eye orbit occurs with, the help of six eye muscles (also called extraocular, muscles) namely – superior oblique, inferior, oblique, superior rectus, inferior rectus, external, rectus and internal rectus., These 6 extraocular muscles are governed by the, cranial nerves III (oculomotor), IV (trochlear) and, VI (abducens)., Eye movement disturbances can cause images to, fail to focus on corresponding portions of the retina,, thus resulting in double vision (diplopia)., General structure of eye are the outer fibrous, tunic, the middle vascular tunic and the inner, nervous tunic., Fibrous coat consists of sclera and cornea., Sclera and uvea are mesodermal and rest of the, eye is ectodermal., The white of the eye is called sclera which helps, maintain the shape of the eye ball and also, provides a means of attachment for the muscles, that move the eye., Sclera consists of tough white connective tissue., In the front of the eye the sclera becomes transparent, forming the cornea., Cornea is transparent because the collagen fibres, in this region are more regularly arranged and do, not reflect light., Cornea is nonvascular (due to which its, transplantation is successful) and convex anteriorly., The cornea admits light to the interior of the eye, , l, , l, , l, l, , l, , l, l, , l, , l, l, l, , l, l, , l, , and bend the light rays and contributes to the, formation of a clear image., Cornea receives its nutrients from the tears and, aqueous humour that fills the chamber behind, it. The cornea admits light to the interior of the, eye and bends the light rays so that they can be, brought to a focus., Cornea and rest of the sclerotic layer is covered by, another very thin, vascularized (containing blood, vessels) and transparent membrane called, conjunctiva., Conjunctiva is composed of stratified epithelium, and is kept clean by the reflex blink mechanisms., Vascular coat (commonly referred as uveal tract), is deeply pigmented with melanin and reduces, reflection of stray light within the eye., The vascular tunic is made up of the choroid (the, thin, dark, bloodvessel containing layer behind the, retina), the ciliary body (that makes the fluid in, the front chamber of the eye and helps to support, the lens) and the iris (the tissue that makes up the, pupil)., Choroid layer prevents reflection of light inside, the eye., The choroid coat forms the iris (a diaphragm) in, the front of the eye. This, too, is pigmented and is, responsible for eye “colour”., The pupil is the opening (or black dot) in the, centre of the iris that regulates the amount of, light received by the retina., The iris has radial and circular muscles which, allow it to vary the opening to it called the pupil., Pupil becomes smallest in bright light and in dim, lighter it becomes larger., The size of its (iris) opening, the pupil, is variable, and under the control of the autonomic nervous, system. In dim light (or when danger threatens),, the pupil opens wider letting more light into the, eye. In bright light the pupil closes down. This, not only reduces the amount of light entering the, eye but also improves its imageforming ability., Atropin is a chemical used by doctors to dilate, the pupil., Ciliary body immediately behind the peripheral, margin of the iris is thicker and less vascular than, choroid. Its inner surface is folded to form ciliary, processes., Present within the ciliary body are ciliary muscles
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 421, , ☼ĚňřĚ– ▒ŕĹďňř, , HUMAN EYE, , Composed of three coats (walls), , Fibrous coat, (Tunica fibrosa), l Outer coat, l Thick and tough layer, made of dense avascular, connective tissue, , l, l, , Vascular coat, (Tunica vasculosa, or Uvea), Middle coat, Highly vascularized, and pigmented layer, , comprises of, Sclera, Cornea, Posterior, Anterior, and opaque and transparent, (5/6th part), (1/6th part), Choroid, (Uvea), Lies in contact with, sclera and remains just, b e h i n d th e r e t in a, forming the posterior, 5/6th of the middle coat, , Optic, Lines choroid, sensory, and differentiated into, two parts, , Pigmented part, , Nervous coat, (Tunica interna), Innermost coat, , consists of delicate,, non vascular light sensitive, coat called retina, , differentiated into, three layers, , Ciliary body, Iris, Immediately behind Anterior part, lies, the peripheral margin behind the cornea., of iris, , Formed of 3 parts, , Ciliary, Nonsensory, formed by simple, layer of pigmented cells that lines, ciliary body and iris respectively, , Irridial, , Nervous part, , Transparent, made of 3 layers, , Photosensitising, layer of visual cells, (Receptor cells), , Rods, Contain rhodopsin, pigment, vision in, dim light, , Layer of bipolar, nerve cells, , Cones, Contain iodopsin pigment, responsible for, colour vision hence colour appreciation, comes only when the light is bright, , Ganglion cells that, form nerve fibres, (called optic nerves)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 422, , l, , l, , l, , l, , l, , l, , l, l, l, l, l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , as circular sheet of smooth muscle fibres that form, bundles of circular and radial muscles which, alter the shape of the lens during accomodation., Accomodation is an adjustment for distant and, close vision during which contraction of ciliary, muscles releases tension in the suspensory ligaments, and allows the lens to elastically recoil and bulge, out on both of its sides. This increases the, convexity of the lens and increases the level of, refraction of light passing through it., The lens is a soft, transparent, elastic & biconcave, structure, attached by suspensory ligaments to, the ciliary body., The lens is responsible for focussing light coming, in through the pupil onto the retina in the back, of the eye., The cells that forms the lens contain a protein called, crystalin which is almost transparent and allows, light to pass through., The ciliary muscles of the ciliary body contract, or relax which varies the shape of the lens so that, light can be focused on the inner layer – the retina., The lens and the sensory ligament divide the, interior of the eyeball into two chambers –, aqueous and vitreous chamber., The aqueous chamber itself consists of two, chamber– anterior and posterior., Anterior chamber is the space between the iris, and cornea., Posterior chamber is the space between lens and, iris., Both anterior chamber and posterior chamber are, filled with a fluid called aqueous humour., Aqueous humour fills space between the cornea, and the lens., In addition to supplying the cornea and lens with, nutrients, the aqueous humour helps to maintain, the shape of the eye., Aqueous humour is produced and renewed, every four hours by the ciliary body., The large space between the lens and the retina is, filled with a viscous matrix called vitreous humor., Aqueous humour a clear fluid produced by the, ciliary body maintains the shape of the cornea, and supply nutrition to both lens and cornea while, vitreous humour (a gellike substance that helps to, maintain the round shape of the eye maintains the, shape of the eyeball and contribute to intraocular, pressure and also to the focussing of light on the, retina., , l, l, , l, l, l, l, l, , l, , l, , l, , l, l, , l, , l, , Aqueous and vitreous humors are rich in, vitamin C., A narrow hyaloid canal passes through vitreous, humor from centre of lens to blindspot (found in, rabbit not in man)., Canal of Schlemm drains aqueous humor and, passes to blood., Nervous coat is the innermost ocular coat that lines, the eyeball ending at the margin of the pupil., Retina is delicate, inner, nonvascular light, sensitive coat of the eyeball., It is differentiated into three parts – optic, ciliary, and iridial., Ciliary and iridial parts are nonsensory and formed, of a single layer of pigmented cells that lines the, ciliary body and iris respectively., The irregular margin of the pars optica lying internal, to the junction of choroid and ciliary body is called, ora serrata retinae., The retina acts like the film in a camera and, transmits electrical images through the optic, nerves to the brain., The retina may be divided into ten layers, from, the outside they are 1. pigment layer, 2. the, photoreceptor layer of rods and cones, 3. external, limiting membrane, 4. external nuclear layer (cell, bodies of rods and cones), 5. external plexiform, layer (synapses of the rods and cones), 6. internal, nuclear layer (bipolar cells), 7. internal plexiform, layer (synapses of the bipolar cells with the ganglion, cells), 8. ganglion cell layer, 9. nerve fibre layer,, 10. internal limiting membrane., The retina contains the light receptors the rods, and cones (and thus serves as the “film” of the eye)., The retina also has many interneurons that process, the signals arising in the rods and cones before, passing them back to the brain., The rods contain a purple coloured photosensitive, pigment rhodopsin (formed from vitamin A) and, are sensitive even in dim light and dark. The cones, have a violet coloured photosensitive pigment, iodopsin and are sensitive to bright light and colour, perception., The three types of cones are– red absorbing cones, (erythrolabe) which absorb best at the relatively, long wavelengths peaking at 565 nm; green, absorbing cones (chlorabe) with a peak absorption, at 535 nm and blue absorbing cones (cyanolabe), with a peak absorption at 440 nm.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☼ĚňřĚ– ▒ŕĹďňř–, l, , l, , l, l, , l, , l, l, l, l, , l, , l, , l, , l, , l, , The nerve fibres in the retina converge and leave, the eye ball to form the optic nerve to conduct, nerve impulses from the eye ball to the brain., The spot at the back of the eye, from where optic, nerve fibres leave is free from rods and cones. This, spot is devoid of the ability for vision and is, called the blind spot., Macula lutea or yellow spot or area centralis is, in the exact centre of the retina., Cones are most densely concentrated in the central, fovea, a small depression in the centre of macula, lutea., The fovea centralis is the area of sharpest vision, (or more distinct vision) because of high, concentration of cones and they are smaller and, more closely packed than elsewhere on the retina., Ability for vision is highest in the fovea., Peripheral portion of retina is most suitable for, detecting motion i.e moving objects., Rods are absent in fovea & macula., Photopic vision is associated with cones., Light splits rhodopsin (visual purple) into a pigment, retinene (= retinol), an aldehyde derivative of, vitamin A and a protein scotopsin (opsin). The, process of splitting is called bleaching. This, depolarizes the rod cells to release a, neurotransmitter, transmitting the nerve impulse to, the bipolar cells, ganglion cells and then to the, optic nerves., Vitamin A is an important constituent of retinene, so its deficiency causes deficiency of rhodopsin, inducing night blindness. Red green colour, blindness is hereditary., Path taken in the eye ball by light rays are –, conjunctiva ® cornea ® aqueous humour ® lens, (through pupil) ® vitreous humour ® retina., The retina converts light energy into electrical, signals and sends them to the brain via the optic, nerve. In the brain the electrical signals are, translated into an image that is perceived in an, upright position., The eyelids are extensions of the skin of the face,, and they are designed to protect the eye. The outer, surface of the eyelid is covered with skin and, sometimes contains the cilia (eyelashes). The inside, is lined with a pinkwhite coloured conjunctival, membrane., The nictitans or third eyelid arises from the inside, corner of the eye and contains a strong cartilage, , l, , l, , l, l, l, l, l, l, , 423, , support and a tear gland. It is also designed as an, extra protective mechanism for the eye., The lacrimal system, which includes the lacrimal, (major tear) gland and the gland of the third eyelid,, is responsible for tear production and drainage, of tears away from the eye., Harderian glands, found in whale, mice, shrew, etc., are located close to the inner angle of eye &, secrete a lubricant for nictitating membrane., Rabbit and man do not possess harderian gland., Pecten, a comblike structure is found in eye of, birds., Grandy’s corpuscles is a special type of merkel’s, corpuscles present in skin of beak & tongue in birds., Binocular vision is found in mammals & birds, (owl)., Retina of owl contains only rods and fowl contains, only cones., Tapetum lucidum, made up of crystalline layer, with zinc, cystein & guanin, increases sensitivity, of vision., , Disorders of eye, l, , l, , l, l, l, , l, l, l, l, l, l, , l, , Myopia, also called short sightedness is, characterized by longer eye ball & focal point in, front of retina., Hypermetropia, also called long sightedness, is, characterized by short eye ball in anteriorposterior, direction and focal point behind the retina., Presbyopia is inability to focus on nearby objects, due to loss of elasticity of crystalline lens., Cataract is loss of transparency of the lens., Trachoma is a chronic contagious conjunctivitis, caused by infection of a bacterium Chlamydia, trachomatis., Astigmatism is a condition in which irregular lens, or cornea produce a blurred image., Deficiency of any cone pigment result in, colourblindness., Protanopia is red colour blindness., Deuteronopia is green colour blindness., Tritanopia is blue colour blindness., Glaucoma is a condition in which loss of vision, occurs because of an abnormally high intraocular, pressure in the eye may be due to blockage of canal, Schlemm [a venous channel at the junction between, the iris and the cornea (anterior chamber angle)]., It may cause blindness., Squint results in diplopia or two images. It occurs
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 424, , ŕďőĽę– ĐĽŐńŐĹť, , due to weakness in ocular muscle or due to defect, in position of the two eyes., , ORGAN OF HEARING EARS, l, l, , l, , l, l, l, l, l, l, , l, , l, , l, , l, , l, , l, , Ears are statoacoustic organs meant for both, balancing & hearing., Ear contains both receptors that respond to, movements of the head and receptors that convert, sound waves into nerve impulses. Impulses from, both types of receptors are transmitted via the, vestibulocochlear (VIII) cranial nerve to the brain, for interpretation., The ear of a human adult consists of three, structural and functional divisions : the external, ear, the middle ear, and the inner ear., External ear consists of pinna (auricle), auditory, canal & tympanic membrane., Pinna is nonfunctional (vestigial) in human., It is an immovable cartilaginous structure that, lead into the auditory canal., In case of mammals like cats, dogs & elephant,, pinna is movable., Pinna, the outer visible part of the outer ear, is, meant for collecting sound waves., The pinna consists of a cartilaginous framework of, elastic connective tissue covered with skin. The, lower flexible lobe (called lobule) is the only part, of the pinna which is not supported by cartilage., The external auditory meatus is a Sshaped, short, canal extending from the pinna to the ear drum, (tympanic membrane or tympanum)., Deeper within the meatus are ceruminous glands, ( waxsecreting glands), which keeps the tympanum, soft and waterproof and together with the hairs, prevent foreign objects from reaching the ear drum., Tympanic membrane (also called ear drum) is, a thin, delicate membranous structure that vibrates, in response to the sound waves tapping on its, outer surface., Tympanum is composed of an outer concave layer, of stratified squamous epithelium and an inner,, convex layer of low columnar epithelium., It is innervated by the auriculotemporal nerve, [a branch of the mandibular portion of the trigeminal, (V) cranial nerve] and the auricular nerve ( a branch, of the vagus (X) cranial nerve]., The middle ear is a narrow air filled cavity, (tympanic cavity) located in the temporal bones, of the skull. It is separated from the external auditory, , l, l, , l, l, , l, l, l, , l, , l, , l, , l, , l, l, l, l, , l, , l, , meatus of the outer ear by the tympanic membrane., Middle ear is connected to pharynx by an air filled, tube called eustachian canal., The eustachian canal maintains the balance in air, pressure between two sides of the eardrum thus, allows it to vibrate freely when sound wave, strike it., The pharyngeal opening of eustachian tube is closed, by tensor palati., Middle ear consists of three tiny bones (called ear, ossicles) that vibrate in response to the vibrations, of the ear drum., Three ear ossicles are : hammer shaped malleus,, anvil shaped incus and stirrup shaped stapes., Stapes bone and its muscle ‘stapedius ’ are the, smallest in the human body., There are two small skeletal muscles the tensor, tympani which attaches to the malleus; and the, stapedius which attaches to the stapes. They, contract reflexly and very quickly to protect the ear, against loud noises., The tensor tympani pulls the malleus away from, the tympanic membrane while the stapedius pulls, the stapes away from the oval window and, changes its orientation 90 degrees., The auditory ossicles transmit sound induced, vibrations of the ear drum to the fluid called, endolymph, filling the internal ear., Tympanic cavity is connected with auditory capsule, by two apertures – oval window (fenestra ovalis), and round window (fenestra rotundus)., The internal ear or inner ear is called labyrinth, consisting of two parts – bony labyrinth,, membranous labyrinth., Bony labyrinth is filled with a fluid called, perilymph., Membranous labyrinth contains a fluid called, endolymph., Membranous labyrinth is divided into three parts –, vestibule, semicircular canal & cochlear duct., Vestibule is a central sac having larger upper utriculus, & a smaller lower sacculus sac containing granules, of calcium carbonate called otolith (ear stones)., Both utricle and saccule contain receptors which, are sensitive to gravity and linear movements of, the head., Utriculus and sacculus, connected by a small narrow, sacculoutricular duct, are often called otolith, organ.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 425, , ☼ĚňřĚ– ▒ŕĹďňř, , Outer Ear, (external ear), , EAR, , Consists of 3 major parts, , Consists of 3 parts, Pinna, , Auditory canal, , Tympanum, , Collect sound waves and, funnels it through the ear, canal to the ear drum, , (also called auditory, meatus), , (Ear drum), Separates external auditory canal, from middle ear., , Between pinna and, tympanic membrane., , Sound in the form of air waves, causes the membrane to vibrate, and these vibrations are, transmitted to the attached, auditory ossicles., , Middle ear, Consists of 2 parts, Auditory ossicles, , Tympanic cavity, , [i.e. three interconnected bones called , hammer (malleus), anvil (incus) and stirrup (stapes)], , Consists ear drum and, two openings called, fenestra ovalis and, fenestra rotunda., , Cross the space of middle ear in series and connect, the tympanic membrane to the oval window., Help to convert sound waves to mechanical, vibrations in tissue and fluid filled chambers., , Inner ear, (also called membranous labyrinth), Consists of 3 parts, Vestibule, Composed of 2 chambers of, utricle and saccule., Contains macula, a special, group of sensory cells., Macula functions as sensors, of gravity and linear, movement., , Semicircular canals, , Cochlea, , Consist, of, cristae, ampullaris as sensory, regions in their dilated, portion called ampulla., , Consists of cochlear duct arising, from sacculus., , These function as sensors, of angular movement., , Cochlear duct is middle, compartment of cochlear canal., Have three chambers scala, vestibuli, scala media (containing, organ of corti for sound, perception) and scala tympani.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 426, , l, l, l, , l, l, l, , l, , l, l, , l, , l, l, l, l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Macula, a group of sensory cells are found in both, sacs., Macula takes part in maintaining static, equilibrium., The sense organ of the utricle is called the macula, triculi which is an oval thickened area in which, fibres of the vestibular branch of the acoustic nerve, terminate. It is covered with hair cells which respond, to movement of the endolymph., The saccule has openings into the endolymphatic, duct and the cochlear duct., The sense organ of saccule is the macula sacculi., Crus commune is the dorsal part of utriculus., Anterior and posterior semicircular canals arise, from crus commune., Semicircular canals are three semicircular ducts, borne over the utriculus at right angles to one, another., Three semicircular canals are – anterior vertical,, posterior vertical and lateral horizontal., The lower end of each semicircular canal has a, swelling called ampulla containing a group of, sensory hair cells called cristae., Cristae, covered by a mass of gelatinous material, (cupula) has longer sensory hairs & lacks otolith, (particle of calcium carbonate)., Cristae maintains dynamic equilibrium of the, body., There are two types of equilibria – static, equilibrium and dynamic equilibrium., Static equilibrium refers to orientation of the body, (mainly head) relative to gravity., Dynamic equilibrium is the maintenance of the, body position in response to sudden movements., The receptor organs for equilibrium are the, sacculus, utriculus and semicircular canals. All, of these are known as vestibular apparatus., Vestibular apparatus is a type of proprioceptor., Utriculus and sacculus are considered to be sense, organs of static equilibrium. The three semicircular, canals maintain dynamic equilibrium., Semicircular canals responds to rotatory, movement of head. The crista is stimulated by, movement of endolymph. This movement causes, distortion of hair cells and effect neural impulse, from ampulla. The direction and rate of, displacement of the cupula (which is bent in the, opposite direction to head movement) are both, detected by the receptor cells. Linear acceleration, , l, , l, l, l, l, l, l, , l, , l, , l, l, l, l, l, l, , l, l, , is detected by both the maculae and cupulae., The utricle responds to vertical movements of, the head and the otoconia (regions of the walls, of utricle and saccule, called maculae, contain, receptor cells which have their hair like process, embedded in a gelatinous mass that contain CaCO3, granules, this mass is called an otoconium), produce maximum stimulation when pulling the, receptor hairs downwards when the body is, upside down., The saccule responds to sideways movement of, the head., Cochlea (auditory region of internal ear) is a long, coiled tubular and blind outgrowth of sacculus., Cochlea is divided into 3 chambers – scala, vestibuli, scala media & scala tympani., Scala media is also known as cochlear duct., Scala media contains endolymph while the other, two chambers contain perilymph., Two partitions in cochlea are dorsal vestibular, membrane, also called Reissner’s membrane,, between scala media and scala vestibuli & ventral, basilar membrane between scala media and scala, vestibuli., Helicotrema, a small whole or narrow passage, permits continuity between scala vestibuli & scala, tympani., Scala media has receptor organ for hearing called, organ of corti containing receptor hair cells,, Deiter’s cell & cells of Hensen etc., Organ of Corti (also called spiral organ) rests on, the basilar membrane., Tectorial membrane is a thin, gelatinous ribbon, like sheet of connective tissue., Tectorial membrane overhangs the hair cells in close, contact with tissue., The organ of Corti is stimulated by sound waves or, nerve impulse of hearing starts from organ of Corti., Organ of Corti is associated with hearing., The perception of sound by a mammal involves the, stimulation of mechanoreceptors located on organ, of corti., The measuring unit of sound is decibel., Ear is most sensitive to frequency 10003000 cycles/, sec., , Disorders of ear, l, , Labyrinth is an infection or inflammation of the, inner ear causing dizziness and loss of balance.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 427, , ☼ĚňřĚ– ▒ŕĹďňř–, l, , l, , l, , l, , l, l, l, l, , l, , l, , Meniere’s disease is an inner ear fluid balance, disorder that causes episodes of vertigo, fluctuating, hearing loss, tinnitus (a raging or roaring in the ears),, and sensation of fullness in the ear., Otitis media is an infection or inflammation of the, middle ear. This inflammation often begins when, infections that cause sore throats, colds, or other, respiratory or breathing problems spread to the, middle ear., Presbyacusis is a hearing loss occurring with age., It occurs due to decreased blood supply to the, inner ear possibly due to heart disease, high blood, pressure or arteriosclerosis or hereditary factors., Tinnitus is a ringing sensation in the ears caused, by irritative stimulation of either the inner ear or, the vestibulocochlear nerve. In this the person hears, when there is no real sound. It is usually, accompanied by hearing loss., Ear is most sensitive to frequency 10003000, cycles/sec., Inflammation of ear drum is called myringitis., Deafness means impairment of hearing. It can occur, at any age., Deafness is classified principally as being of two, types : conductive loss of hearing and sensorineural, deafness., Conductive loss occurs when the ossicular chain, (the bones in the middle ear – the hammer, anvil, and stirrup) do not function properly. This type of, loss can be surgically treated., Sensorineural deafness (or nerve deafness) occurs, from damaged nerves in the inner ear and can, generally be treated only by the use of a hearing aid, (if there is residual hearing). Sensorineural deafness, can result from long exposure to excessive noise, levels, diseases such as whooping cough or measles,, or the ageing process., , ORGAN OF SMELL–NOSE, l, l, , l, , l, l, , The nose may be called the sense organ for olfaction, (smell)., Receptors for smell occur in a modified form of, pseudostratified epithelium covering a part of the, nasal mucosa. It is called olfactory epithelium., The olfactory receptor cells function as, chemoreceptors. They are stimulated by specific, chemical substances and produce impulse of smell., Olfactory receptor cells are bipolar neurons., Jacobson organ is concerned with smell, present, , l, , in the anterior part of nasal cavity. This organ is, well developed in dogs and snakes & less, developed in birds and mammals., Continuous smelling of an odour make the receptor, cells immune to the odour and the receptor cells, fail to respond to the sensation. It is called olfactory, adaptation. This is the reason that a person cease, to smell the perfume on his dress after sometime., , ORGAN OF TASTE–TONGUE, l, l, , l, l, l, , l, , l, l, l, l, l, l, l, l, l, , l, , Taste buds are the organs for taste sensation, (gustatory receptors)., They are present on the papillae of mucous, membrane on the surface of tongue. The human, tongue bears about 10,000 taste buds. Some taste, buds occur in hard palate, pharynx and epiglottis also., Papillae containing taste buds are of four types , foliate, fungiform, filiform & circumvallate., Foliate is absent in man., Filiform does not contain taste buds and are located, near centre & most of them on the upper surface of, tongue. Hence nongustatory in function., Foliate is present on the posterior part of tongue,, anterior to circumvallate papillae and found in rabbit, & other mammals., Circumvallate (largest type) form an inverted V, shaped row at the posterior part of the tongue., Types of taste buds corresponding to the taste are, – sweet, sour, bitter & salt., Sweet taste are produced by various class of organic, molecules including sugar, glycols & aldehydes., Salt taste is associated with anions of ionizable, salt., Sour taste is produced by weak acid like the one, present in unripened fruits etc., Bitter taste refers to the taste of alkaloids (little, quinine, caffeine)., Moth & butterflies have their chemoreceptors on, antennae., A taste bud has taste receptor cells or gustatory, cells which act as chemoreceptors., These cells bear sensory hair at free ends, which, are connected to nerve fibres at other end. The, taste bud communicates to the surface of the tongue, by a narrow taste pore., The anterior part of the tongue is most sensitive to, sweet taste, back to the bitter and sides to salty, and sour. The taste of chillies is a sensation of, burning pain of the pain receptors of the tongue.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 428, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 45, , Endocrine System, l, , l, , l, l, l, l, , l, , l, l, l, l, l, , l, , Endocrine system are those systems which, generally control long term activities of target, organs as well as physiological process such as, digestion, metabolism, growth, development and, reproduction in contrast to more rapid activities, under the control of nervous system either directly, or indirectly., The endocrine system carries out a wide variety of, physiological processes through chemical, messengers called “hormones.”, Endocrine system comprise endocrine glands and, their hormones., Gland is an organ, tissue or cell that secretes a, chemical for performing a particular function., Types of glands are exocrine, endocrine and, heterocrine., Exocrine gland is a gland whose secretions perform, metabolic activity on the surface or into a particular, region by means of ducts. Eg. sebaceous gland,, salivary gland, liver etc., Endocrine gland is an isolated gland that pour, their secretion directly into venous blood or lymph, for passage to different organs in order to control, their growth, function, metabolism etc., Endocrine gland is also called as ductless gland., Heterocrine gland (mixed gland) consists of both, exocrine and endocrine region., Endocrinology is the study of endocrine glands,, hormones and their effect., Father of endocrinology was Thomas Addison., The major glands that make up the human endocrine, system are the pineal body, hypothalamus, pituitary,, thyroid, parathyroids, adrenals and the reproductive, glands (the ovaries and testes)., The pancreas is also part of this hormone secreting, system, even though it is also associated with the, digestive system because the exocrine part of the, , l, , l, , l, , l, l, l, , l, , l, , l, , l, l, , pancreas also produces and secretes digestive, enzymes into the intestine., Although the endocrine glands are the body’s main, hormone producers, some nonendocrine organs , such as the brain, heart, lungs, kidneys, liver,, thymus, skin, and placenta also produce and, release hormone., Hormones are chemical regulators or chemical, messenger of the body which are secreted in, response to changes in the environment inside or, outside the body., Lag period is a period between the secretion of, hormone from endocrine gland and biological, response from target organ., First hormone discovered in 1902 by Bayliss and, Starling was secretin., Hormones may be excitatory or inhibitory in their, effects., On the basis of their chemical composition,, hormones may be divided into three categories –, amine hormones, steroids and proteinaceous and, peptide hormones., Amine hormones are derived from tyrosine amino, acids and have amino group, eg. thyroxine,, epinephrine and norepinephrine., Steroids are fat soluble and have sterol group. They, are derived from cholesterol, eg. hormones of, adrenal cortex, testis and ovaries., Proteinaceous and peptide hormone are water, soluble and includes hormones of hypothalamus,, pancreas and pituitary., Hormones can be divided into lipophilic (lipid, soluble) and hydrophilic (water soluble)., The lipophilic hormones, all of the steroid, hormones and thyroxine as well as other lipophilic, regulatory molecules (including the retinoids, or, vitamin A) can easily enter cells. This is because
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 429, , ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ, , l, , l, , l, , l, , l, , l, , l, , l, l, l, l, l, , l, , l, l, , l, , the lipid portion of the cell membranes does not, present a barrier to the entry of lipophilic regulators., Water soluble hormones in contrast can not pass, through cell membranes. They must regulate their, target cells through different mechanisms., Hormone action at the cellular level begins with, the association of the hormone and its specific, receptor., Hormones can be classified by the location of the, receptor and by the nature of the signal or second, messenger used to mediate hormone action within, the cell., Hormone receptors are found either exposed on, the surface of the cell or within the cell, (cytoplasm), depending on the type of hormone., Peptide hormones usually act at a specific, receptor on the plasma membrane. The signal is, then communicated to the cytoplasm by one of the, signal transduction pathways (e.g., via a receptor,, G proteins, adenylyl cyclase, AMP, and kinase)., Steroids, produced by endocrine glands of, mesodermal origin, easily pass through both the, plasma and nuclear membranes., Steroid bind with a specific Hormone Response, Element (HRE) in the nucleus to activate DNA, transcription., The thyroid hormone’s mechanism of action, resembles that of the steroid hormones., Hormone action is usually shortlasting because, hormones are catabolised by the liver., Hormones which control activity of other endocrine, glands and/or growth are called trophic hormones., When two hormones work together it is called, synergistic hormone. Eg. FSH & LH., Moulting hormone (ecdysone) and juvenile, hormone (corpora allata) are important in insect, development., Local hormones (also called tissue hormone, para, hormone or paracrine) are those hormone which, do not pass into blood but diffuses to the target and, work upon adjacent tissue., Types of local hormones are neurohormones,, prostaglandin and pheromones., Neurohormones are secreted by nerve cells and, released into tissue fluid at synapses by the synaptic, vesicles of axon, eg. acetylcholine and, norepinephrine., Prostaglandin are fatty acid derivatives and, , l, , l, l, , l, l, , l, , l, l, l, l, l, , secreted by many organs (kidney, gonads, seminal, vesicle, thymus etc.) into their tissue fluid., Prostaglandin controls either contraction/, relaxation of smooth muscles or dilation/, contraction of blood capillaries., Prostaglandin were first reported in semen of man, and produced by prostate gland., Kinin or bradykinins are polypeptides that causes, contraction of smooth muscles and dilation of blood, vessels., The gaseous hormone, nitric oxide (also an air, pollutant) is also a local hormone., New researches demonstrated that the NO linked to, haemoglobin allow blood vessels to expand or, contract, depending on how much of the molecule, is present. This principle is used in ‘viagra’ medicine., Pheromones are the chemicals used for, communication amongst individuals of the same, species., Pheromones are also known as ectohormones or, sex attractants or saniochemicals., Pheromones are volatile in nature and travel, with air., It invoke a specific response in other members like, recognition, warning and attraction., Bombykol is a sex attractant pheromone produced, by female silkworm moth., A deer produces seven different types of, pheromones, all from different sites and with, different functions., , PINEAL GLAND, l, , l, , l, l, , l, , The pineal gland (or epiphysis) is a stalked, small, rounded organ. It is located on the midline, attached, to the posterior end of the roof of the third ventricle, in the brain., The pineal body is located above the superior, colliculus and behind and beneath the stria, medullaris, between the laterally positioned, thalamic bodies., The pineal body is part of the epithalamus., The pineal gland consists mainly of pinealocytes,, but four other cell types have been identified:, interstitial cells, perivascular phagocyte, pineal, neurons and peptidergic neuronlike cells., It secretes two biogenic hormones – melatonin, and serotonin.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 430, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The pineal gland calcifies with age and melatonin, production correspondingly decreases. This decline, in melatonin has been suggested to be a trigger for, the ageing process., Also called epiphysis cerebri, the pineal gland is, important because it is the centre for the production, of the hormone melatonin and it contains magnetic, material in birds and other animals. It is a centre, for navigation., Melatonin, or 5methoxyNacetyltryptamine, is a, hormone produced by pinealocytes in the pineal, gland, and a derivative of the amino acid tryptophan., The production of melatonin by the pineal gland, is stimulated by darkness and inhibited by light., There is a pathway from the retinas to the, hypothalamus called the retinohypothalamic, tract. It brings information about light and dark, cycles to a region of the hypothalamus called, the suprachiasmatic nucleus (SCN). From the, SCN, nerve impulses travel via the pineal nerve, (sympathetic nervous system) to the pineal gland., These impulses inhibit the production of, melatonin. When these impulses stop (at night,, when light no longer stimulates the, hypothalamus), pineal inhibition ceases and, melatonin is released. The pineal gland is, therefore a photosensitive organ and an, important timekeeper for the human body., , l, , l, , l, , l, , To synthesize melatonin, serotonin is converted to, Nacetylserotonin by the enzyme 5HT N, acetyltransferase. Nacetylserotonin is then, converted to melatonin by the enzyme 5, hydroxyindoleOmethyltransferase., Melatonin has important effects in integrating, photoperiod and affecting circadian rhythms., Consequently, it has been reported to have, significant effects on reproduction, sleepwake, cycles and other phenomena showing circadian, rhythm., Melatonin delays sexual development and inhibit, ovarian functions, hence referred as, antigonadotrophic hormone., Brain sands (also called acervuli), found in pineal, body, are particles of calcium salts (CaCO3 &, Ca3PO4)., , Nobel Prize Laurate Julius Axelrod performed, many of the seminal experiments elucidating the, role of melatonin and the pineal gland in, circadian rhythms., , HYPOTHALAMUS, l, , l, l, , l, l, , l, , l, , l, , l, , l, l, , l, l, , The hypothalamus, a region of the brain that, controls an immense number of bodily functions,, is located in the middle of the base of the brain,, and encapsulates the ventral portion of the third, ventricle., The hypothalamus is the main link between the, endocrine and nervous systems., Nerve cells in the hypothalamus control the pituitary, gland by producing chemicals that either stimulate, or suppress hormone secretions from the pituitary., Herring bodies formed in hypothalamus store, neurosecretory substance., The hypothalamus regulates homeostasis. It has, regulatory areas for thirst, hunger, body, temperature, water balance, and blood pressure., In addition to secreting neuromodulators, the, hypothalamus synthesizes and secretes a number, of neurohormones., These neurohormones are known as releasing, hormones because the major function generally is, to stimulate the secretion of hormones originating, in the anterior pituitary gland., The hypothalamopitiutary axis is the unit formed, by the hypothalamus and pituitary gland, which, exerts control over many parts of the endocrine, system., This unit functions by means of interaction of the, nervous and endocrine system whereby the nervous, regulates the endocrine system and endocrine, activity modulates the activity of the CNS., Neurohormones were first discovered by Guillemin, and Schally (Nobel Prize 1977)., Types of neurohormones are – TRH or TSHRH;, GnRH; ACTHRH or CRH; SRH or GHRH; GIH;, PRH or LTHRH; PIH or LTHRH; MSHRH or, MRH and MSHIH or MIH., Thyrotropin releasing horomone (TRH) is the, simplest of the hypothalamic neuropeptides., It is also called thyrotropin releasing factor (TRF),, thyroliberin or protirelin.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ–, , The sequence of TRH was first determined, and the hormone synthesized by Roger, Guillemin and Andrew V. Schally in 1969., l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , TRH is involved in the control of body, temperature and that it has psychological and, behavioural effects., The TRHsecreting cells are subject to stimulatory, and inhibitory influences from higher centres in, the brain and they also are inhibited by circulating, thyroid hormone. In this way TRH forms the, topmost segment of the hypothalamicpituitary, thyroid axis., GnRH (gonadotrophins releasing hormone), stimulates the synthesis and release of the two, pituitary gonadotrophins – luteinizing hormone, (LH) and folliclestimulating hormone (FSH)., There may be two distinct releasing hormones –, FSHRH and LHRH in female and one ICSH, RH in male., Neurons that secrete GnRH have connections to an, area of the brain known as the limbic system, which, is heavily involved in the control of emotions and, sexual activity., Some individuals have hypogonadism (in which, the functional activity of the gonads is decreased, and sexual development is inhibited) due to a, congenital deficiency of GnRH., Abnormalities in the GnRH secretion result, in subnormal fertility, abnormal or absent, menstruation, and possibly cystic disease of, the ovary or even ovarian cancer., Adrenocorticotropinreleasing hormone (CRH), stimulates not only secretion of corticotropin or, adrenocorticotropin (ACTH) hormone in the, pituitary gland but also the synthesis of, corticotropin in the corticotropinproducing cells, (corticotrophs) of the anterior lobe of the pituitary, gland., CRH, also called corticoliberin, is a polypeptide, hormone and neurotransmitter involved in the stress, response., Excessive secretion of CRH leads to an increase, in the size and number of corticotrophs in the, pituitary gland, often resulting in a pituitary, tumor. This, in turn, leads to excessive stimulation, of the adrenal cortex, resulting in high circulating, levels of adrenocortical hormones., , l, , l, , l, , l, , l, , 431, , Like CRH, growth hormonereleasing hormone, (GHRH) is a large peptide and stimulate anterior, pituitary to produce and secrete growth hormone., GHRH secretion is stimulated by stresses,, including physical exercise, and secretion is, blocked by a powerful inhibitor called, somatostatin., GH releasing hormone (GHRH) is also known as, somatotropin releasing hormone (SRH) or, somatocrinin., Negative feedback control of GHRH secretion is, mediated largely through compounds called, somatomedins. Somatomedins is a growth, promoting hormone that are generated when tissues, are exposed to growth hormone itself., Growth inhibiting hormone (GIH) or, somatostatin inhibits adenohypophysis to secrete, growth hormone., Somatostatin is also secreted by delta cells of, stomach, intestine, and pancreas. It binds to, somatostatin receptors., , l, l, , l, , l, l, , l, , l, , Somatostatin is also a powerful inhibitor of, pituitary TSH secretion., Somatostatin, like TRH, is widely distributed in, the central nervous system and in other tissues., It serves an important paracrine function in the, islets of Langerhans, by blocking the secretion of, both insulin and glucagon from adjacent cells., Somatostatin has emerged not only as a powerful, blocker of the secretion of GH, insulin, glucagon,, and other hormones but also as a potent inhibitor, of many functions of the gastrointestinal tract,, including the secretion of stomach acid, the, secretion of pancreatic enzymes, and the process, of intestinal absorption., Prolactin releasing hormone (PRLRH) stimulate, anterior pituitary to secrete prolactin (PRL or LTH)., Prolactin inhibiting hormone (PRLIH), also, called dopamine, stops synthesis of LTH by anterior, pituitary., In brain, dopamine functions as a, neurotransmitter, activating dopamine receptors., Its (dopamine) chemical name is 4(2aminoethyl), benzene1, 2diol and it is abbreviated as DA., Dopamine can be supplied as a medication that, acts on the sympathetic nervous system, producing, effects such as increased heart rate and blood, pressure.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 432, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Deficits in dopamine levels are implicated as one, of several possible causes for Adult attentiondeficit, disorder (AADD), and some types of medications, used to treat Attentiondeficit hperactivity disorder, (ADHD/ADD) will help to stimulate dopaminergic, systems, leading to potentially heightened sensation,, for those afflicted by it and receiving treatment for, it., Melanocyte stimulating hormone (MSHRH), induces intermediate lobe of pituitary to secrete, MSH., Melanocyte stimulating hormone inhibiting, hormone (MSHIH) stops synthesis of MSH., , l, , l, , l, , PITUITARY GLAND, l, , l, l, l, l, l, , l, , l, l, , l, , l, , l, , Pituitary is the smallest, pea shaped endocrine, gland which is connected to hypothalamus by an, infundibular stalk formed of connective tissue with, blood capillaries and nerves., It lies in the cavity called sella turcica of sphenoid, bone of skull., It i s a ls o c a ll ed a s hy pop hy s is or, hypothalamus ce re br i., Pituitary gland is cranioepithelial in origin., Removal of pituitary is known as hypophysectomy., The pituitary gland is sometimes called the, “master” gland of the endocrine system, because, it controls the functions of the other endocrine, glands., The pituitary gland itself consists of three lobes:, the anterior lobe, the intermediate lobe and the, posterior lobe., Each lobe of the pituitary gland produces certain, hormones., Pituitary is a composite gland comprising anterior, lobe (adenohypophysis) and posterior lobe, (neurohypophysis) on the basis of anatomy and, embryology., Adenohypophysis (makes 75% of total weight), develops as an outgrowth of pharynx called, Rathke’s pouch., The adenohypophysis consists of three principal, types of hormones secreting parenchymal cells, according to the pattern of staining : acidophils, (which stains with acidic dyes), basophils (which, stain with basic dyes), and chromophobes (which, have only pale staining)., Acidophils are subdivided into two classes –, , l, , l, l, , l, , l, , l, , lactotropes (mammotropes) and somatotropes., Lactotropes produce prolactin and somatotropes, produce GH., Basophils are subdivided into three classes –, corticotropes, thyrotropes, and gonadotropes., Corticotropes produce ACTH and lipotropic, hormones (LPH); thyrotropes produce TSH; and, gonadotropes produce LH and FSH., Chromophobes probably are acidophile or, basophile that have lost their specific staining, properties after releasing their hormonecontaining, granules., Adenohypophysis is formed of three parts pars, distalis (largest), pars tuberalis (highly vascular, region) and pars intermedia (also called, intermediate lobe of pituitary gland)., Pars distalis and pars tuberalis are collectively, known as anterior lobe of pituitary or, adenohypophysis., Hormones of anterior pituitary are called trophic, hormones or tropins., Secretion of the trophic hormones is controlled by, neurohormones of hypothalamus through a, feedback mechanism which operates either at gene, level or at enzyme level., Hormones of adenohypophysis are :, –, GH (growth hormone, somatotropin or, somatotrophic hormone, STH), –, TSH (thyroid stimulating hormone), –, ACTH (adrenocorticotrophic hormone), –, GnTH (gonadotrophic hormones), –, PRL or LTH (prolactin or lactogenic or, luteotrophic hormone)., GH (or STH) is a proteinaceous hormone whose, effects on the tissues of the body can generally be, described as anabolic (building up)., Growth hormone is also called somatropin and, somatotropin. The genes for human growth, hormone are localized in the q2224 region of, chromosome 17 and are closely related to human, chorionic somatomammotropin (hCS, also known, as placental lactogen) genes., GH, hCS, and PRL are a group of homologous, hormones with growthpromoting and lactogenic, activity., , l, , GH stimulates growth of body by synthesis and, deposition of protein in tissue, increased glucose
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ, , l, , l, , l, l, , l, , l, , l, l, , l, , l, , l, l, , level in blood by decreased secretion of insulin,, increased cell division and increased growth of, bones by increased absorption of calcium from, intestine., GH promotes body growth by:, –, binding to receptors on the surface of liver, cells, –, this stimulates them to release insulinlike, growth factor1 (IGF1; also known as, somatomedinC), –, IGF1 acts directly on the ends of the long, bones promoting their growth, In childhood, hyposecretion of GH produces the, stunted growth of a dwarf. Dwarfism is, characterised by retarded physical growth but, normal alertness and intelligence., The dwarf are called midgets., Simmond’s disease in a adult is a rare condition, in which patient becomes thin and show sign of, premature ageing. It is caused due to hyposecretion, of growth hormone., Hypersecretion of GH leads to gigantism in, childhood before the closure of epiphyseal plates, at the end of bones and in adults it leads to, acromegaly., Gigantism is characterised by extra ordinary growth, in height (78 feet) caused by abnormal elongation, of long bones. And acromegaly is characterised by, abnormal growth of hand, feet, face, especially, lower jaw. Appearence may be ape like., Gigantism is also called pituitary giant., Secretion of thyroid stimulating hormone (TSH), is controlled by feedback mechanism from, thyroid hormone., TSH consists of two subunits – the alpha and the, beta subunit. The a (alpha) subunit is identical to, that of human chorionic gonadotrophin (hCG),, luteinising hormone (LH), folliclestimulating, hormone (FSH). The b (beta) subunit is unique to, TSH, and therefore determines its function., TSH control structure and functioning of thyroid, gland to synthesize and release of its hormones, thyroxine and triiodothyronine., TSH is a proteinaceous hormone, secreted by pars, distalis., Hyposecretion of TSH leads to thyroid atrophy, while hyperactivity produces symptoms similar to, Grave’s disease., , 433, , Table : Effects of TSH deficiency, Body weight increases, Metabolic, Oxygen consumption, decreases, Heat production, decreases, Basal metabolic rate, decreases, CNS, Impaired mentally, Poor memory and, concentration, Drowsiness, Motor nervous system Activity decreases, Sympathetic nervous Activity decreases, system, Cardiovascular, , Gl tract, , l, , l, , l, l, l, l, , l, l, , Bradycardia, Reduced output and, blood pressure, Activity decreased, Constipation, , ACTH is a peptide hormone which controls the, structure and functioning of adrenal cortex, especially secretion of glucocorticoids and sex, corticoids., Hypersecretion of ACTH leads to rheumatoid, arthritis while hyposecretion leads to excessive, growth of adrenal cortex., Gonadotrophins or gonadotrophic hormone, (GTH) regulates the growth and function of gonads., The two main gonadotrophins are – FSH and LH/, ICSH., FSH or follicle stimulating hormone are also called, gametokinetic factor., FSH is a proteinaceous hormone which stimulates, spermatogenesis and growth of seminiferous, tubules in testes; maturation of Graafian follicle, and secretion of estrogen (by the cells of ovarian, follicle) and progesterone (from the corpus, luteum)., LH (luteinizing hormone) is known as gamete, releasing factor., In sexuallymatured females, LH, –, Stimulates the follicle to secrete estrogen in, the first half of the menstrual cycle, –, Surge triggers the completion of, meiosis I of the egg and its release (process, called ovulation) in the middle of the cycle
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 434, , ŕďőĽę– ĐĽŐńŐĹť, , –, , l, , l, l, , l, , l, , l, l, , l, , Stimulates the nowempty follicle to develop, into the corpus luteum,which secretes, progesterone during the latter half of the, menstrual cycle., In males LH acts on the interstitial cells of the, testes stimulating them to synthesize and secrete, the male sex hormone, testosterone and other, androgens for the development of secondary sex, organs and secondary sexual characters., LH in males is also known as interstitial cell, stimulating hormone (ICSH)., Hyposecretion of ICSH results in impaired, development of external genitalia and LH results, in sterility in females., PRL (prolactin) acts to initiate and maintain milk, secretion by the mammary glands, hence it is, also known as hormone of maternity., PRL works with other hormones such as, oxytocin, which actually causes milk ejection, and, oestradiol, progesterone, glucocorticoids, GH,, thyroxine and insulin, which prepare the mammary, gland for milk production., The hormone prolactin is downregulated by, dopamine and is upregulated by estrogen., PRL secretion is under inhibitory control of, dopamine. This means that if the link between the, hypothalamus and pituitary is severed PRL secretion, increases, unlike all other pituitary hormones, where, production would decrease without stimulatory, control of the hypothalamus., TSH has a stimulatory affect on PRL secretion., Oestradiol increases PRL production and levels of, PRL rise during pregnancy and remain high, during lactation., During pregnancy, prolactin levels rise as rising, estrogen promotes prolactin release, causing, further maturing of mammary glands, preparing, them for lactation. After childbirth, prolactin, levels fall as the internal stimulus for them is, removed. Sucking by the baby on the nipple, promotes further prolactin release, maintaining, the ability to lactate., , l, , Hyperprolactinaemia is a common cause of, menstrual problems in women, and high levels of, prolactin can cause gynaecomastia (breast, enlargement) in men. It can also cause inappropriate, galactorrhoea (milk production) in males and females., , l, , l, , l, , Usually, in the absence of galactorrhea, lactation, will cease within one or two weeks of the end of, demand breastfeeding., High prolactin levels also tend to suppress the, ovulatory cycle by inhibiting both FSH and, GnRH., Prolactin is also called luteotrophic hormone, (LTH) because it also stimulates the corpus luteum, of the ovary to secrete progesterone hormone., Sometimes, newborn babies (males as well as, females) secrete a milky substance from their, nipples. This substance is commonly known as, Witch’s milk. This is caused by the foetus being, affected by prolactin circulating in the mother, just before birth, and usually stops soon after, birth., , l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, , MSH (also called intermedin), a polypeptide, hormone is produced by pars intermedia so called, intermediate lobe of pituitary., It stimulates synthesis and dispersal of melanin, pigment present in skin of fish, amphibia and some, reptiles., It is nonfunctional in man., Neurohypophysis develops as a downgrowth of, hypothalamus., The neurohypophysis has three main components –, pars nervosa (infundibular process), media, eminence and infundibular stalk., Pars nervosa, also called the posterior lobe, does, not actually produce hormones, but stores and, secretes hormones made by the hypothalamus., Therefore posterior lobe is also called storage, organ., Pituicyte cells formed in neurohypophysis, secrete, two octapeptide hormones – vasopressin and, oxytocin from supraoptic and paraventricular nuclei, respectively., Vasopressin is also called antidiuretic hormone, (ADH) or pitressin or arginine vasopressin, (AVP)., Antidiuretic hormone (ADH) is a peptide hormone, and acts on the kidneys, concentrating the urine, by promoting the reabsorption of water and salt, into the cortical collecting duct., ADH is activated by “water receptors” in both, the extracellular fluid volume and the intracellular, fluid volume., In the extracellular fluid the activators are mainly
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 435, , ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ, , l, , l, , l, , l, , l, , l, l, , baroreceptors in the veins, atria, and arterioles. In, the intracellular fluid the activators are mainly, osmoreceptors in the hypothalamus., Ethanol and caffeine block the release of ADH, from the posterior pituitary gland. This decrease in, water reabsorption leads to a higher volume of, urine output., ADH is under negative feedback control. A fall, in blood volume stimulates release of ADH. Also,, a fall in the arterial partial pressure of oxygen and, a rise in partial pressure of carbon dioxide stimulate, ADH release., Secretion of ADH is also affected by the, angiotensin II, adrenaline, cortisol and sex, steroids. At the level of the hypothalamus, pain,, trauma, nausea and vomiting, and a rise in external, temperature increase AVP secretion, and, psychological and emotional stimuli also affect its, release., Overproduction of ADH can occur due to brain, trauma. It leads to water retention, serum hypo, osmolality, hyponatraemia and hig h urine, osmolality.These effects cause symptoms of, headache, apathy, nausea and vomiting, impaired, conciousness and can be fatal in extreme cases., Underproduction of ADH results in the condition, of diabetes insipidus. Clinical signs are excretion, of large volumes of urine (diuresis, 10 litre, urine/day) leading to dehydration and thirst, (polydipsia), as well as increased plasma osmolality., Oxytocin secretion occurs in response to nervous, stimulation of the hypothalamus., Oxytocin causes contraction of the smooth muscle, of the uterus (hence called birth hormone) and, also of the myoepithelial cells lining the duct of the, mammary gland (hence called milk ejection, hormone)., Synthetic oxytocin is also called as pitocin and, syntocinon. Oxytocin is destroyed in the, gastrointestinal tract, and therefore must be, administered by injection or as nasal spray., Oxytocin has a halflife of typically about three, minutes in the blood. Oxytocin given, intravenously does not enter the brain in, significant quantities it is excluded from the, brain by the bloodbrain barrier. Drugs, administered by nasal spray are thought to have, better access to the CNS. An oxytocin nasal spray, has been used to stimulate breastfeeding., , l, , l, , l, , l, , Release of oxytocin is under positive feedback, control. Stimulation of mechanoreceptors in the, uterus and vagina during parturition cause a rise in, oxytocin levels up to a maximum until the stimulus, is no longer present and the action of the hormone, is no longer needed., Negative feedback is an important factor in, controlling the hypothalamic pituitarytarget, organ a xis function. O nce hypotha la mic, hormones stimulates the release or inhibition of, the pituitary hormone, this may then act as a, target gland, such as the thyroid, causing release, of further hormones of causing metabolic effects., The action of hypothalamic hormones may be, inhibited by long feedback loops from the target, gland hormone or by short feedback loops from, the pituitary hormone. There may also be direct, feedback from the target gland hormone to the, pituitary gland., Positive feedback also plays a part in certain, systems. For example, in the situation where high, levels of oestradiol in the blood cause a surge in, LH levels during the menstrual cycle., , THYROID GLAND, l, l, , l, , l, , l, l, , l, , l, l, , The thyroid gland is located in the front of the, neck, below the larynx (voice box)., The small, twoinch thyroid gland consists of two, lobes, one on each side of the windpipe, connected, by tissue called the isthmus., The thyroid tissue is made up of two types of, cells: follicular cells and parafollicular cells, (Gcells)., Gcells or parafollicular cells are group of, endocrine cells scattered in connective tissue and, between the thyroid follicles., Thyroid follicles contains thyroglobulin., Thyroglobulin, a glycoprotein in colloidal, suspension, is a stored formed of thyroxine and an, exocrine secretion product of follicular epithelial, cells., Follicular cells, secrete iodinecontaining, hormones called thyroxine or tetraiodothyronin, (T4) and triiodothyronine (T3)., Thyroglobulin contains multiple copies of one, amino acid tyrosine., The level of thyroglobulin present in the body can, be measured with blood tests.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 436, , ŕďőĽę– ĐĽŐńŐĹť–, , Table : Physiological effects of thyroid hormones., Target tissue, , Effect, , Mechanism, , Heart, , Chronotropic, Inotropic, , Adipose tissue, Muscle, Bone, Nervous system, Gut, Lipoprotein, Other, , Catabolic, Catabolic, Developmental, Developmental, Metabolic, Metabolic, Calorigenic, , Increase number and affinity of badrenergic receptors., Enhance responses to circulating catecholamines., Increase proportion of a myosin heavy chain (with higher, ATPase activity)., Stimulate lipolysis, Increase protein breakdown., Promote normal growth and skeletal development., Promote normal brain development., Increase rate of carbohydrate absorption., Stimulate formation of LDL receptors., Stimulate oxygen consumption by metabolically active tissues, (exceptions : testes, uterus, lymph nodes, spleen, anterior pituitary)., Increase metabolic rate., , l, , l, l, l, , l, l, l, , l, , l, l, l, , Thyroglobulin serves a useful readout for the, presence or absence of thyroid cells, particularly, in patients with thyroid cancer where it serves as, a “tumor marker”., The thyroid needs iodine to produce the, hormones., The thyroid plays an important role in regulating, the body’s metabolism and calcium balance., The T4 and T3 hormones stimulate every tissue in, the body to produce proteins and increase the, amount of oxygen used by cells., T3 is 3 4 times more potent than T4., T4 and T3 are deiodinated in the liver, kidneys and, many other tissue., The level of T4 circulating in the blood controls its, release from the thyroid gland by negative, feedback, mechanism, involving, the, hypothalamus and anterior pituitary., If excess T4 is present in the blood it switches off, its own production by switching off production, of TRH (thyrotropin releasing hormone) by the, hypothalamus and TSH (thyroid stimulating, hormone) by the anterior pituitary., Thyroxine control BMR (basal metabolic rate) of, the body., The BMR of a normal adult man is 40 cal/m2 and, 37.5 cal/m2 in woman., Apart from carrying out metabolic and regulatory, function, thyroxine also controls some, , l, , l, , l, , l, , l, l, , l, l, , l, , developmental process like metamorphosis., Eg. amphibia & teleost fish., It controls urine output, maintains nervous and, muscular tonus, increase the oxidation of glucose, in tissue and also acts on SA node & maintains, the normal heart beat and also reduce the, formation of ketone bodies etc., In its (thyroxine) absence or presence of thiourea, (antithyroid substance), tadpoles remains in larva, stage indefinitely. They stimulate tissue, differentiation, therefore they affect metamorphosis, of a tadpole into an adult frog., Hypothyroidism results in cretinism, myxoedema,, endemic or simple goitre or colloid goitre and, Hashimoto’s disease., Hypothyroidism is the condition in which the, thyroid is underactive (i.e., it is producing an, insufficient amount of thyroid hormones)., Hypothyroidism is the most common thyroid, disorder., The most common cause of hypothyroidism is, an autoimmune reaction, where the body produces, antibodies against the thyroid gland., Severe hypothyroidism can lead to a condition, called myxoedema., Myxoedema is also called Gull’s disease, developing in adult life, most commonly in, middleaged women., Myxoedema is characterized by puffy appearance
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ, , l, l, l, , l, , l, , l, l, l, , l, , l, , l, , l, , due to subcutaneous accumulation of fat, low BMR,, low heart rate and body temperature, retarded, sexuality., Cretinism is a condition produced in infants and, children due to lack of thyroid hormone., Children who are hypothyroid from birth or before, are called cretins., Cretinism usually results from a congenital defect., However, it can develop later if there is a lack of, iodine in the diet, or if the thyroid is diseased or, surgically removed., The main cause of congenital hypothyroidism, are maternal iodine deficiency, inborn errors of, thyroid hormone synthesis, maternal antithyroid, antibodies that cross the placenta etc., Cretinism causes very serious retardation of, physical and mental development; if the condition, is left untreated, growth is stunted and the physical, stature attained is that of a dwarf. In addition, the, skin is thick, flabby, and waxy in colour, the nose, is flattened, the abdomen protrudes, and there is a, general slowness of movement and speech., If the condition commences after adulthood is, reached it is called myxoedema (described earlier)., Goitre is a nonspecific term describing, enlargement of the thyroid gland., Symptoms of goitre are feeling of pressure;, increased neck size; a feeling of narrowness, as if, there’s a lump in the neck region; difficulty in, swallowing and hoarseness., When the dietary iodine intake falls below, 50mg/dL, thyroid hormone synthesis is inadequate, and secretion declines., Endemic goitres are those which occur at high, incidence in certain geographic regions. They are, associated with iodine deficiency but other factors, must be involved as the prevalence varies in areas, with similar low levels of iodine. Factors such as, the intake of goitrogens or metabolic defects in, thyroxine synthesis may be important., Simple goitres arise from compensatory, hyperplasia in an attempt to maintain thyroid, hormone levels. Once a state of euthyroidism is, reached, colloid accumulates hence, the term, colloid goitre., Hashimoto’s thyroiditis is a type of autoimmune, , l, l, , l, , l, l, , l, , l, , l, , l, l, , 437, , thyroid disease in which the immune system attacks, and destroys the thyroid gland. Hashimoto’s, prevents the gland from producing enough thyroid, hormones for the body to work correctly. It is the, most common form of hypothyroidism., Hashimoto’s disease is also known as suicide of, thyroid gland., Hyperthyroidism means overactivity of the, thyroid gland, resulting in too much thyroid, hormone in the bloodstream which leads to, overactivity of the body’s metabolism., Symptoms may include: nervousness, irritability, increased perspiration, thinning of the skin; fine,, brittle hair; weak muscles, especially in the upper, arms and thighs; shaky hands; fast heartbeat; high, blood pressure; increased bowel movements;, weight loss; sleeping difficulty; eye sensitivity, to light; staring; confusion, irregular menstrual, cycle., Grave’s disease is most often associated with, hyperthyroidism., Grave’s disease is categorized as an autoimmune, disorder (in which circulating antibodies formed, against the TSH receptor activate the receptor,, making the gland hyperactive). The disease is most, common in young to middleaged women and, tends to run in families., Symptoms of Graves’ disease are identical to, hyperthyroidism, with the addition of three other, symptoms – goitre (enlarged thyroid which may, cause a bulge in the neck), bulging eyes, (exophthalmos due to swelling of extraocular, muscle), thickened skin over the shin area., Thyroiditis (the inflammation of the thyroid gland), causes temporary hyperthyroidism, usually followed, with hypothyroidism., Calcitonin (non–iodinated polypeptide hormone), is secreted from the parafollicular or C cells in, the thyroid gland, but it is also synthesized in a, wide variety of other tissues, including the lung, and intestinal tract., Calcitonin is also called thyrocalcitonin (TCT)., Calcitonin plays a role in calcium and, phosphorous metabolism. In particular, calcitonin, has the ability to decrease blood calcium levels at, least in part by effects on two wellstudied target, organs : bone and kidney.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 438, , ŕďőĽę– ĐĽŐńŐĹť–, , Bone : Calcitonin suppresses resorption of bone, by inhibiting the activity of osteoclasts, a cell, type that “digests” bone matrix, releasing calcium, and phosphorous into blood., Kidney : Calcium and phosphorous are, prevented from being lost in urine by, reabsorption in the kidney tubules. Calcitonin, inhibits tubular reabsorption of these two ions,, leading to increased rates of their loss in urine., l, , l, , l, , l, , l, , l, , l, , The most prominent factor controlling calcitonin, secretion is the extracellular concentration of, ionized calcium., Elevated blood calcium levels strongly stimulate, calcitonin secretion, and secretion is suppressed, when calcium concentration falls below normal., When serum calcium levels rise, calcitonin secretion, occurs, bone resorption decreases and serum, calcium level falls again., The calcitonin hormone works together with the, parathyroid hormone to regulate calcium levels, in the body., Calcitonin is used to treat hypercalcemia resulting, from a number of causes, and has been a valuable, therapy for Paget disease, which is a disorder in, bone remodeling., Calcitonin also appears to be a valuable aid in, the management of certain types of osteoporosis, and loss of bone density (due to dissolution of, PTH)., In birds, fish and amphibians, calcitonin is secreted, from the ultimobrachial glands., , l, , l, l, , l, , l, , l, , THYMUS, l, , PARATHYROID GLANDS, l, l, , l, , l, , l, , Parathyroid glands are small glands which are, located in the neck behind the thyroid., There are usually 4 parathyroid glands which are, normally a little smaller than a pea, 2 in the left, lobe of the thyroid and 2 in the right lobe., The normal role of the parathyroid glands is to, control the blood calcium by secreting parathyroid, hormone (PTH)., The levels of blood calcium are constantly, monitored by a protein expressed by parathyroid, cells, designated the calcium sensing receptor., Parathyroid hormone (secreted by chief cells) is, also called parathormone (PTH) or Collip’s, hormone., , The parathyroid hormone stimulates the, following functions –, –, Release of calcium by bones into the, bloodstream, –, Absorption of food by the intestines, –, Conservation of calcium by the kidneys., PTH has an effect that opposes the effect of, calcitonin., PTH affects the synthesis of 1, 25 dihydroxy, cholecalciferol (a metabolite of vitamin D), which, indirectly affects serum calcium by increasing the, efficiency with which dietary calcium is absorbed, in the gastrointestinal tract., Persistent excess production of PTH may lead to, the development of a high level of blood calcium,, referred to as hyperparathyroidism., Hyperparathyroidism may be associated with, the development of osteoporosis (destruction of, bone with increased incidence of fractures), kidney, stones, impaired kidney function, increased, thirst or increased frequency of urination, osteitis, fibrosa cystica (means normal bone is replaced by, cysts and fibrous tissue) and sometimes, stomach, upset and ulcers., Hyposecretion of PTH leads to tetany, characterised by decreased serum Ca 2+ and, increased serum phosphate, and decreased urinary, phosphate, muscle spasm, twitching, increasing, neuroexcitation etc., , l, , l, l, l, , l, , The thymus (throne of immunity) is a ductless, gland which lies in the upper part of the, mediastinum behind the sternum and extends, upwards into the root of the neck., The thymus reaches its greatest size at puberty,, after which it undergoes slow involution and both, cortical and T lymphocytes are reduced in peripheral, blood., The thymus is the first developing lymphoid, organ., The main function of the thymus is to develop, immature Tcells into immunocompetent Tcells., The thymus is divided into two distinct, compartments– the outer cortex and the inner, medulla., Both regions are densely populated with, lymphocytes (or thymocytes while in the thymus).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ–, l, l, , l, , l, , l, , l, l, , l, , The maturation of the thymus and other, lymphoid tissue is stimulated by thymosine., Thymosine, a polypeptide hormone secreted by, reticular epithelial cells, increases the rate of growth,, accelerates cell division, helps in maturation of, genital organs and produces lymphocytes and, antibodies., Thymic or Hassal’s corpuscles made of, concentrically arranged epithelioreticular cells, become more common into adulthood. They act as, phagocytes., The thymus plays an important role in the, development of the immune system in early life,, and its cells form a part of the body’s normal, immune system., Thymopoietin, also called thymin, depresses, neuromuscular transmission, induces Tcell, markers, and has a role in the generation of cytotoxic, T cells and prevention of autoimmunity., The human thymus, especially in the foetus,, supports erythropoiesis and granulopoiesis., The thymus is also present in many other animals., When animal thymus tissue is sold in a butcher, shop or at a meat counter, thymus is known as, sweetbread., Hypersecretion of thymosine hormone may lead, to Myasthenia gravis, characterised by abnormal, muscular excitation., , l, , l, l, , l, l, l, , l, l, , l, , ADRENAL GLAND, l, , l, , l, , l, , l, , The adrenal gland is called supra renal gland, because it is situated on the anteriosuperior aspect, of the kidney and receives its blood supply from, the adrenal arteries., Adrenal gland is separated into two distinct, structures – the adrenal medulla (10–20% and, ectodermal in origin) and the adrenal cortex (80–, 90% and mesodermal in origin), both of which, receive regulatory input from the nervous system., The adrenal medulla is the body’s main source, of the catecholamine hormones like epinephrine, (adrenaline) and norepinephrine (nor, adrenaline)., Adrenal medulla is composed of masses of, catecholamines secreting cells surrounded by, complex network of blood vessels., Catecholamines secreting cells are sometimes called, , l, , l, , l, l, , 439, , chromaffin cells because their granules stain a, brownish colour when exposed to solutions, containing dichromate ions., The release of epinephrine and norepinephrine, is controlled by the central nervous system, through the preganglionic sympathetic fibres in, the medulla., These hormones are derived from aminoacid, tyrosine., Dopamine is an intermediate in the biosynthesis, of adrenaline and noradrenaline from the tyrosine, and phenylalanine., A deficiency of dopamine results in Parkinson’s, disease., Secretion of adrenaline is 510 times higher than, noradrenaline., These hormones are secreted for meeting an, emergency as in cold, emotional stress, pain, anger,, fear etc., Adrenaline is also known as emergency hormone., It increases blood pressure, basal metabolic rate,, lipolysis in adipose tissue to increase level of fatty, acids in blood, acts as vasodilator, increase, respiration rate as it dilates trachea, increases sugar, level in blood by stimulating glycogenolysis in liver, and skeletal muscle and slows down peristalsis., Noradrenaline more or less resembles adrenaline, in its biological effects except that it operates, during normal state, exercises, lesser effect on, cardiac activity and produces greater, constriction of blood vessels in muscles., Hypersecretion of adrenaline causes hypertension,, high level of sugar in blood and urine, high, metabolic rate, nervousness and sweating etc., Adrenal cortex, composed of cortical cells, secretes, 40 different steroid hormones which are collectively, called as corticoids., Corticoids are divided into mineralocorticoids,, glucocorticoids and sexcorticoids., The adrenal cortex can be divided into three, distinct layers of tissue based on cell type and, function –, –, Zona glomerulosa (outer) mineralocorticoid, production, primarily aldosterone, –, Zona fasciculata (middle) glucocorticoid, production, mainly cortisol (roughly 95%), –, Zona reticularis (inner) sex corticoids,, androgen production, including testosterone
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 440, , l, , l, l, , l, , l, , l, l, l, l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Two common mineralocorticoids (secreted by zona, glomerulosa) are aldosterone and deoxycortic, osterone., Aldosterone is also called as saltretaining, hormone., In response to increased potassium levels or, decreased blood flow and sodium to the kidneys,, cells of the zona glomerulosa secrete the, aldosterone into the blood as part of the renin, angiotensin system., Aldosterone regulates the body’s concentration of, electrolytes, primarily sodium and potassium, by, acting on the distal convoluted tubule of kidney, nephrons to increase potassium excretion; increase, sodium reabsorption; and increase water reabsorp, tion through osmosis., Zona fasciculata responsible for the production, of glucocorticoids are the primary effectors of, adrenocorticotropic hormone (ACTH)., ACTH stimulates cortical cells to secrete gluco, corticoids., Important glucocorticoids are cortisol and cor, ticosterone., The primary glucocorticoid released by the adre, nal gland is cortisol., Cortisol enhances metabolism in several ways:, –, Stimulating the release of amino acids from, the body, –, Stimulating lipolysis, the breakdown of fat, –, Stimulating gluconeogenesis, the production, of glucose from newlyreleased amino acids, and lipids conserving glucose by inhibiting, uptake into muscle and fat cells., Glucocorticoids are used maximum in medicine, for allergic condition, rheumatoid arthritis, skin, disease and asthma etc., Cells of the zona reticularis provide a secondary, source of androgens such as testosterone,, dihydrotestosterone (DHT), androstenedione, and, dehydroepiandrosterone (DHEA). These enhance, muscle mass, stimulate cell growth, and aid in the, development of the secondary sexual characteris, tics., Addison’s disease usually results due to deficient, secretion of aldosterone and cortisol., During addison’s disease, excessive loss of Na+,, Cl– and HCO3– takes place and level of K+ ion, increases in blood. Imbalance in sodium potassium, ratio’s alter muscle and nerve functions., , l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, l, l, , Hypersecretion of aldosterone due to adrenal, cortical tumor causes aldosteronism or Conn’s, syndrome., Conn’s syndrome is characterised by rise in blood, volume & blood pressure, muscular weakness, high, plasma Na + (due to decreased renal excretion), resulting in kidney damage and polyuria, tetany,, hypokalemic alkalosis., Excessive loss of sodium ion is known as acidosis., Acidosis means decrease in pH of blood from, 7.4 to 6.8., Over secretion of cortisol causes cushing, syndrome, characterised by high sugar level in, blood, loss of sugar in urine, loss of weight, high, Na+ & low K+ concentration in plasma, rise in blood, volume and blood pressure etc., Cushing syndrome is also produced by tumors of, non–endocrine tissues that secretes substances with, CRH activity or more commonly ACTH., Cushing disease, same as cushing syndrome is, caused by oversecretion of cortisol due to, excessive hormone stimulation by adrenal cortex, by tumor/hyperplasia (due to increased cell mass), of anterior pituitary., Cushing disease mainly occurs in females and, causes obesity, hypertension, glycosuria (sugar in, urine), virilism., Excessive secretion of sex corticoids results in, virilism or appearance of male secondary characters, like male voice, beard, moustaches in females., Hirsutism is the presence of facial and excess, body hair in females due to adrenal virilism, while, it causes gynaecomastia in males characterised by, enlarged breast., Secretion of glucocorticoids and sexcorticoids are, regulated by ACTH of pituitary., Mineralocorticoid release is stimulated by the, activity of renin and angiotensin., Adrenal gland is also called 4 S gland (= sugar, metabolism, salt retaining, sex hormones, source, of energy) and 3 F gland (fright, fight and flight.), , PANCREAS, l, l, l, , The pancreas is a retroperitoneal organ., Pancreas is the second largest gland located in the, loop of duodenum., It is an heterocrine gland in which exocrine part, occurs as acini while the endocrine part, (23%) is represented by islets of Langerhans or, pancreatic islets.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 441, , ◄ňęŐĘŕĽňĚ– ☼ťřŚĚŇ–, l, , l, l, , l, , l, l, , l, , l, l, l, l, , l, l, , l, l, , l, l, l, , Control of the exocrine function of the pancreas, occurs by the enzymes gastrin, cholecystokinin and, secretin, which are secreted by cells in the stomach, and duodenum, in response to distension and/or, food and which cause secretion of pancreatic juices., The acinar cells are specialized to secrete the, proteins in the digestive process., Hormones of pancreas, secreted by different types, of endocrine cells present in islet of Langerhans,, are a cell (secretes glucagon); b cell (secretes, insulin); g cell (secretes gastrin); d cell (secretes, somatostatin); and F cell (secretes pancreatic, polypeptides)., Islets have fenestrated capillaries (typical of all, endocrine tissues) which facilitate hormone, transport., Insulin and the glucagon are the chief hormones, produced in the islet tissue., Glucagon (secreted by a cells of pancreas), is a, proteinaceous hormone whose secretion is, stimulated by low blood sugar level., Glucagon stimulates glycogen breakdown and, glucose synthesis in the liver thereby increasing, the blood glucose concentration., Excess of glucagon may cause glycosuria due to, presence of sugar in urine., Glucagon is antagonistic to insulin., Insulin (secreted by bcells of pancreas), is also, called hypoglycaemic or antidiabetic factor., Rising blood glucose levels stimulates insulin, secretion and falling blood glucose levels stimulate, glucagon synthesis., Insulin is anabolic hormone whereas glucagon is, catabolic hormone., Normal range of blood sugar is 80120 mg/, 100 ml of blood (80 mg/100 ml before fasting &, 120 mg/100 ml after meal)., Deficiency of insulin causes diabetes mellitus., Diabetes is characterised by polyuria, polydipsia,, weight loss inspite of polyphagia (increased, appetite), hyperglycemia, glycosuria, ketosis, (increased ketone bodies in blood), acidosis, (increased H+ ions in blood) & coma., Polyuria or excessive urination is due to increase, in water content of urine., Polydipsia means excessive thirst inspite of, drinking more and more water., Indication of diabetes start when blood sugar level, increases about 3 times and is more than, , l, l, , l, , l, , l, , l, l, l, l, l, , 150 mg/100 ml of blood due to regular supply from, alimentary canal and failure of cells to absorb, glucose., Diabetes mellitus are of two types – type I diabetes, and type II diabetes., Type I diabetes usually develops before age 40, and it is characterised by loss of bcells with, eventual absence of insulin in the circulation., Type I diabetes is also called juvenile diabetes, and insulindependent diabetes mellitus (IDDM)., It is ketosis prone diabetes means that fatal high, level of ketone bodies increase in the blood due to, severe nonavailability of insulin. Insulin is a, metabolic hormone which prevents ketone body, formation., Type II diabetes usually develops after age 40, and is not associated with total loss of the ability, to secrete insulin., Type II diabetes is also called maturityonset, diabetes and noninsulin dependent diabetes, mellitus. It is ketosisresistant diabetes., Somatostatin (secreted by d cell) is a local hormone, which controls functioning of a and b cells., Somatostatin inhibits the secretion of insulin and, glucagon., Pancreatic polypeptide (secreted by Fcells) check, secretory activity of digestive glands., Gastrin (secreted by g cells) is similar to the one, produced by pyloric stomach., Hypokalaemia means low level of potassium in, blood and ketonaemia refers to presence of ketone, bodies in blood due to increased oxidation of fats., , GONADAL HORMONES, l, l, l, l, , l, l, l, , Gonads (testes in male and ovary in female) are, both exocrine and endocrine in function., Secretion of gonadal hormones are stimulated by, GnTH of pituitary., Endocrine part of testes is formed of group of cells, called interstitial cells or leydig cells., Leydig cells are the most important functional cells, in the interstitium (the space between the, seminiferous tubules of testis)., Leyding cells synthesize and secrete male sex, steroids called androgens., Testosterone (steroid hormone) is the most, abundant androgen released by leydig cells., Testosterone is responsible for the growth and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 442, , l, l, , l, l, , l, l, l, , l, l, l, l, , l, , l, l, l, l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , development of male secondary sex organs (like, epididymis, seminal vesicle etc.) and male, secondary characteristics (like beard, moustaches, etc.), It stimulates spermatogenesis & erythropoiesis., The surgical removal of testes is called castration, or orchidectomy. Cryptorchidism is non descent, of testis from its abdominal origin to testicular sac., Castrated human male are called eunuch or neuter, and oxen (instead of bulls) in case of cattle., Eunochoidism is a hormonal disorder due to non, secretion of testosterone in a genetically male, individual., Just like testes, the ovaries are cytogenic as well, as endocrine in function., Ovaries secrete 3 types of female hormones –, estrogen, progesterone and relaxin., Estrogen, group of steroid hormone is mainly, secreted by follicular epithelial cells of, membrana granulosa of Graafian follicles., Secretion of estrogen is stimulated by LH of, anterior lobe of pituitary gland., Estrogen includes estradiol, estriol and estrone., Principle estrogen is estradiol., Estrogen stimulates the growth and development, of female secondary sex organs and female, secondary sexual characteristics., Estrogen decreases the secretion of FSH while, increases the secretion of LH during menstrual, cycle., During pregnancy, estradiol is secreted by placenta., Progesterone is a steroid hormone secreted by, corpus luteum., Small amount of progesterone is also secreted by, adrenal cortex and placenta., Progesterone is responsible for the maintenance, of pregnancy, hence called as pregnancy, hormone., During pregnancy progesterone helps in attaching, embryo to uterine wall, development of placenta &, growth of secretory alveoli in mammary glands., Progesterone is thermogenic and is probably, responsible for the rise in basal body temperature, at the time of ovulation., Hyposecretion of progesterone results in abortion, and misconception., Progesterone is also called as antiabortion, hormone., , l, , l, , Relaxin is a proteinaceous hormone, secreted by, corpus albicans which is formed from the corpus, luteum at the end of gestation period., Relaxin softens the pubic symphysis so helps in, parturition (child birth) in rats and guinea pig., In women, this role is played by estrogens &, progesterone., , PLACENTAL HORMONES, l, , l, l, , l, , l, l, l, l, , Placenta is the connection between foetus and, uterine wall for physiological exchange like, respiration, excretion, nutrition etc., During pregnancy, placenta also acts as an, endocrine gland., The chorionic villi of placenta secretes two, steroids (estradiol & progesterone) and two, proteins (human chorionic gonadotrophin, HCG, and placental lactogen, PL) hormones., HCG is a glycoproteinaceous hormone that main, tains the corpus luteum for continued secretion of, progesterone so as to maintain the pregnancy., Pregnancy test is confirmed by the presence of, HCG in urine., HPL (human placental lactogenic hormone), prepares the mammary glands to secrete milk., Inhibin hormone is produced by corpus luteum,, placenta & testes., It supplements the effect of excess sex hormones, for depressing gonadotrophic activity (FSH, CH,, ICSH) of pituitary., , OTHER HORMONES, l, , l, l, l, l, , Juxta glomerular region of kidney produces two, hormones – erythropoietin (regulates erythrocyte, production) and renin (changes angiotensinogen, of liver into angiotensin.), Heart produces a peptide hormone, atrial, natriuretic factor (ANF) in case of hypertension., This hormone inhibits renin (in kidney) and ADH, secretion (in pituitary)., Salivary gland produces a proteinaceous hormone,, parotin for calcification of teeth., Gastrointestinal hormones are proteinaceous in, nature. These are of following types – gastrin,, secretin, enterogastrone cholecystokinin,, pancreozymin, enterocrinin, duocrinin and, villikinin., [For the functions of these hormones refer chapter, Nutrition and Digestive System].
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 444, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 46, , Reproduction in, Flowering Plants, l, l, l, l, , Reproduction is the process of formation of new, individuals of a species from the preexisting ones., In lower organism, reproduction occurs commonly, by fission and budding., In higher organisms reproduction occurs with the, help of well developed sex organs., Plants show two types of reproduction asexual, and sexual., , ASEXUAL REPRODUCTION, l, , l, , l, l, , l, , l, l, , Asexual reproduction is the mode of formation of, new individuals from parts of parents without, meiosis and formation of gametes., Basic characteristies of asexual reproduction are–, –, Involvement of single organism without the, production of gametes., –, Cell division are only mitotic in nature., –, Individuals formed are generally identical to, the parent., –, It is a rapid way of reproduction under, favourable conditions., Asexual reproduction is of 3 types agamospermy,, spore formation and vegetative reproduction., Agamospermy is asexual formation of seed, but, embryo inside the seed is produced by abnormal, method omitting meiosis and fertilization., (described later)., Spore formation is seen in algae, fungi, bacteria,, and protistans, where different spore types as, zoospores, aplanospores hypnospores, sporangiospores,, etc. help in reproduction., Spores taking part in asexual reproduction are called, accessory spores or mitospores., Vegetative reproduction is the process of, multiplications from a part of plant body that, function as propagule and develops into new, , l, , l, , l, l, , l, , l, l, l, l, l, , l, , individual. It could be natural or artificial., The technique of propagation in which a portion, gets detached from the plant body and functions as, propagule naturally is called natural vegetative, propagation., Roots of plants like Dalbergia sisso, Murrya sp, etc. develop adventitious buds to grow into new, plant., Root tubers of sweet potato, Asparagus etc. have, adventitious buds that give rise to new plants., Underground stem modification show various, modes of vegetative reproduction as –, –, Suckers in Chrysanthemum produce new, plants., –, Rhizome possess buds to give rise to new, plants., –, Corms of Colocasia possess buds., –, Bulbs of garlic, –, Stem tubes have buds in nodes and internodes., Creeping stems like runner (grass), stolons, (Vallisneria) and offsets (Pistia) gives rise to new, plants from the base of old shoot., A stem segment of Opuntia and other cacti develops, into a new plant after falling on the soil., Leaves of many plants possess adventitious buds, Eg. Bryophyllum., Bulbils develops into new plants after falling on, the ground, eg. Agave., Turions are fleshy buds that develop in aquatic plants, for perennation and propagation, eg. Utricularia., Artificial methods of vegetative reproduction are, the technique developed by man to propagate, desired varieties., The various modes of artificial vegetative, reproduction are – cutting, layering, grafting,, micropropagation etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚőŕŐęśĘŚĽŐň– Ľň– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, , l, l, , l, , l, , l, l, , l, , l, , l, , A cutting is separated portion of root, stem or, leaf. It is very common method employed for artificial, vegetative propagations, eg. sugarcane, roses, Citrus,, Duranta, grapes, cocoa, Bougainvillea., Cut parts must have one node., Auxin like IBA, NAA, IAA are used for stem, cutting because they lead to the quick formation, of adventitious roots., The rooting success varies with species, age (the, younger the better), the position on the donor tree, where the cutting originated (lower is more juvenile, and therefore more successful) and time of year., When the roots appear, the stem is cut below the, level of roots and planted. This method is also, popularly called gootee., Favourable time for planting of cuttings is the, spring., Layering (or soil layering) occurs in nature when, a drooping lower branch contacts the soil and, adventitious roots form at point of soil contact, eg., grapevine, jasmine, strawberry gooseberry etc., Air layering can be done artificially by wounding, a shoot (away from ground) and wrapping the, wound in a moist medium (e.g., Sphagnum), surrounded by a waterproof covering., Air layering is done in plants –, –, Which do not produce adventitious roots easily, –, Whose branches fail to bent due to larger, diameter, –, Whose stems are so mature that latent buds, near the base do not sprout by other methods, of layering., This method of artificial vegetative propagation is, widely used in plants like litchi, Citrus,, pomegranate, guava, Croton etc., l, l, l, l, , l, , l, , l, , Methods of soil layering, Tip layering – Eg blackberry, raspberry., Serpentine layering – Eg Clematis., Mound layering – Eg currant, gooseberry., Trench layering – Eg walnut, , Grafting is the process of attaching a shoot (or, less frequently a bud) from the individual you want, to clone to the root of another tree., The plant of which the root system is to be taken, is called stock and the other of which shoot system, is to be used is known as scion., The success of the grafting mostly depends, upon the union of the cambium of scion and, , l, , l, l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, l, , 445, , stock which results in organic connection, (connection among organs so that transport of, solute, minerals and water occurs in continuous, manner) between them., All shoots sprouting from the stock should be, removed otherwise they will not permit the scion, to grow., Grafting is of three types tongue grafting, wedge, grafting and crown grafting., In tongue or whip grafting stock and scion are, almost of the same diameters. The stock and scion, are given oblique cuts followed by a notch in the, tongue or whip grafting. Then the scion closely fits, over the stock., In wedge grafting a Vshaped notch is given in the, stock, while scion is cut like a wedge. Here also, the stock and scion are almost of the same diameters., In crown grafting, diameter of the stock is many, times than that of scion. So many scions are grafted, on single stock., Grafting is commonly used to establish genetically, superior trees in seed orchards and to propagate, unique trees for horticultural purposes, (e.g.,weeping varieties, infertile flowering cherries)., Grafting is used for quick multiplication and, proper growth of better varieties with weak, roots, eg mango, apple, pear, rubber etc., Bud grafting is another method of artificial, vegetative reproduction. Here a bud with small, portion of surrounding bark is taken from the stem, of a desired plant and inserted into the small slit, made in the bark of stock., Bud grafting is widely practised in roses, plums,, apple etc., Micropropagation is the raising of new plants from, a small plant tissue with the help of tissue culture, technique., Tissue culture is the technique of maintaining and, growing cells, tissues etc and their differentiation, on artificial medium under aseptic conditions inside, suitable containers., Tissue culture is based on totipotent nature of, plant cells or concept of totipotency i.e., each, and every plant cell has the inherent capacity to, develop into a complete plant., Haberlandt first proposed the concept of, totipotency., Steward first developed a full plant from a single, cell of wild carrot root.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 446, , l, l, , l, l, l, , l, , l, l, l, l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Explant is group of cells used in tissue culture., When grown an artificial medium under aseptic, conditions in a suitable condition, the explant forms, an irregular unorganized mass of actively dividing, cells called callus., Process of haploid production from pollen grains, is called androgenesis., Embryoids are nonzygotic or somatic embryo like, structures produced through tissue culture., Embryo culture technique was first started by, E. Hanning (1904) and further improved by, Laibach (1925)., Embryo culture is used in the following –, –, Shortening of breeding cycle, –, To obtain rare hybrids, –, To propagate some rare plants, –, Used as rapid seed viability test., Endosperm culture is used for triploid plant, production., Triploidy is commercially used in many varieties, of apple, banana, sugar beet, tea, watermelon etc., Protoplast culture is mostly used in production, of somatic hybrids., Genetic manipulations can be carried out more, rapidly when plants cells are in protoplast state., New genes can be introduced., Chloroplast + ‘nif’ genes ® Nitroplast., Genetically uniform and disease free clones have, been produced by nucellus culture, eg. Citrus,, mango., Meristem tip culture is used in – clonal, propagation and in obtaining virus free plants., Dry freezed storage of germplasm is, called cryobiology., Importance of vegetative propagation are –, –, Growing of some seedless fruits plants like, banana, grapes, oranges, rose, jasmine etc., –, Vegetative propagation is the only mean to, produce genetically identical offsprings &, preserve a stock of desired variety., –, It is an easier less expensive & a rapid method, of propagation., –, Superior quality of flowers and fruits can be, produced by the method of grafting., –, A large number of disease free identical plants, can be grown in a very short time by tissue, culture technique., , SEXUAL REPRODUCTION, l, , l, l, , Sexual reproduction is the formation of new, individuals through the meiotic gamete formation, and their subsequent fusion during fertilization., Sexual reproduction is also called amphimixis., The study of sexual reproduction in plant includes, microsporogenesis,, megasporogenesis,, pollination, fertilization., , Microsporogenesis, l, l, , l, , l, l, , l, l, , l, , l, l, , l, l, , The formation of microspores or pollens is called, microsporogenesis., Pollen grains are formed inside the anther which, is the fertile part of the stamen or, microsporophyll., The anther consists of two lobes which are separated, in the anterior region by a deep groove and attached, to each other on the back side by sterile tissue, called connective., Each anther lobe consists of two long and cylindrical, pollen sacs or microsporangia., Parietal layer or wall layers of anther contains the, following –, –, Epidermis of single layer for protection, –, Endothecium of single layer for dehiscence, of anther, –, 14 number of middle layers, –, Tapetum, the innermost parietal layer with, cells having dense cytoplasm and large nuclei., Tapetum provides nourishment to developing, microspores., Tapetum also secretes callase enzyme which, dissolves callose substances by which 4 pollens of, a pollen tetrad are united, hence separating, microspores or pollens of a tetrad., Tapetum secretes ubisch bodies which gets, covered with sporopollenin and so increase, thickness of exine., Tapetum is of two types – amoeboid and, secretory., In amoeboid or plasmodial tapetum, the inner, and radial walls breakdown at an early stage and, these cells are free in microsporangia., In secretory or glandular tapetum, the tapetum, remain as such throughout., Pollen kit is the outermost oily, thick, sticky,, coating of pollen grains, mainly composed of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚőŕŐęśĘŚĽŐň– Ľň– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , l, , l, l, l, l, l, l, l, l, , l, l, l, l, , l, l, , l, , l, l, l, , lipids and carotenoids. It is secreted in case of, entomophilous pollen grains., Main functions of pollen kit are –, –, Due to sticky nature, the pollen get attached, to bodies of insects, –, Acts as insect attractant, –, Protects pollens against harmful UV rays., Sporogenous tissue (or archesporial tissue) is, present in the pollen chambers., Sporogenous tissues gives rise to microspores by, microsporogenesis., Primary sporogenous cell given rise to microspore, mother cell (MMC)., Each microspore mother cell gives rise to 4 haploid, microspores or pollen grains., Isobilateral tetrads are formed in monocot., Tetrahedral tetrads are formed in dicots., One microspore is formed from one pollen mother, cell, eg. cypraceae., In member of asclepiadaceae and orchidaceae all, the pollens of an anther lobe are packed in a bag, like structure called pollinium., Pollinia of two adjacent anthers together form a, translator., Polyspory is the occurrence of more than 4 spores, in a pollen tetrad, eg. Cuscuta reflexa., When 4 pollens do not separate and remain in tetrads, it is known as compound pollen., Dehiscence of anthers are of different types –, (i) Longitudinal dehiscence, eg. Datura., (ii) Transverse dehiscence, eg. Ocimum., (iii) Porous dehiscence, eg. Solanum, (iv) Valvular dehiscence, eg. Beberis., Each microspore is a unicellular haploid, oval or, rounded structure., Smallest pollens are present in Myosotis (10 m), and largest pollens are present in some members of, cucurbitaceae and nyctaginaceae (Mirabilis250 m)., Pollen grains are classified according to number, (N), position (P) and character (C) of apertures and, this type of classification is called NPC system., Pollens of Ambrosia of family compositae cause, hay fever., Each pollen grain have two layered walls : exine, and intine., Terms intine and exine were given by, Fristsche (1837)., , Ø, Ø, Ø, Ø, Ø, , l, l, l, l, l, l, l, l, l, l, l, l, l, l, , l, l, , l, l, , 447, , Study of pollen grains or microspores is, called palynology., Geopalynology is the study of fossil pollen, grains., Aeropalynology is the study of pollens, found in air or atmosphere., Iatropalynology is the study of pollens in, criminology and medical aspects., Melittopalynology is the study of pollen, grains in honey., , Pollen grain of monocots contains single germpore, and that of a dicot contains three germpores., The outer layer called exine is thick, tough,, cuticularized and is composed of sporopollenin., Sporopollenin is absent in the pollen grains of, Zostera., The thin areas of the exine are called germ pores, or germ slits., Inner layer called intine is thin, smooth and is, composed of pectocellulose., Exine is differentiated into extexine and endexine., Extexine is further differentiated into foot layer,, baculate layer and tectum., Tectum provides a characteristic sculpturing or, designs over the surface of pollen grains., Microspore or pollen is the beginning of male, gametophytic generation., Development of the male gametophyte (uniform, in all angiosperms) is called microgametogenesis., Male gametophyte when fully developed is a 3, nucleate structure., The pollen grain nucleus grows in size and shifts, to one side near the wall., The protoplast then divides to form small, generative cell and large vegetative or tube cell., Initially, the position of vegetative nucleus is the, terminal portion of pollen tube and generative cells, behind it., Their position will be reversed during the movement, of pollen tube in the stylar canal., On the stigma the pollen grains absorb water and, nutrients from the stigmatic secretion through its, germ pores., The tube or vegetative cell enlarges and comes, out of the pollen grain to form pollen tube., The tube nucleus descends to the tip of the pollen, tube and finally gets degenerated.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 448, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , The generative cell passes into the pollen tube and, divides into 2 male gametes., Nemec (1898) reported pollen grain embryo sac, (or male gametophyte like female gametophyte or, embryo sac) in Hyacinthus (fam. Liliaceae), which, is called ‘Nemec phenomenon’., , Megasporogenesis, l, l, l, l, l, l, l, l, l, l, l, l, l, , l, l, l, , l, l, l, , l, , l, , Gynoecium or pistil is the female reproductive, part and carpel is the unit of gynoecium., Carpel is considered to be modified leaf bearing, ovules or megasporophyll., The folded carpel bears one or more ovules along, the ventral suture., Carpel is distinguished into three parts as stigma,, style and ovary., The integumented nucellus or megasporangium, is called ovule., The main body of the ovule is called nucellus or, megasporangium., Ovary at maturity forms fruit and ovule forms seed., Inside the ovary, there is present either a single, ovule at its base or many ovules on its sides., Arrangement of ovules inside the ovary is called, placentation., The ovule is attached to placenta by means of a, stalk called funiculus., Hilum is the point of attachment of funiculus to, the body of the ovule., The funicle continues along the side of the ovule, as a ridge called 'raphe'., Most important part of the ovule is embryo sac, because embryo and endosperm are formed in this, structure., Embryo sac is called female gametophyte., The opening of the ovule is called micropyle., The place of the ovule where integuments and, nucellus join each other (at the apex of funicle) is, called chalaza., The ovule lacking the funicle is called sessile., Ovules having single integument are called, unitegmic ovule. It is common in gamopetalae., Ovules having 2 integuments are called bitegmic, ovule. Example members of polypetalae and, monocots., When nucellus is not surrounded by integuments,, the ovule is called ategmic, example Santalum, album, Balanophora., Any ovular structure which directs the growth of, , l, l, l, , l, , l, , l, , l, , l, , l, , l, , l, , pollen tube towards micropyle of ovule is called, obturator. It acts as a type of bridge for pollen, tube., Obturator develops from funiculus or placenta., Group of lignified cells below embryo sac in, nucellus is called hypostase., Hypostase is found in families like, amaryllidaceae, liliaceae, euphorbiaceae and, zingiberaceae., Depending upon position of micropyle in relation, to chalaza and funiculus, ovules are of 6 types in, angiosperms. These are – orthotropous, anatropous,, hemianatropous, campylotropous, amphitropous, and circinotropous., Orthotropous or atropous or straight is the most, primitive and simplest type of ovules in, angiosperms., This is erect (i.e., micropyle at upper end) and, here micropyle, chalaza and funiculus are in the, same straight line, e.g., in polygonaceae and, piperaceae., Anatropous or inverted is the most common type, of ovule found in angiosperms (i.e., in 82% of, angiosperm family). Here body of the ovule gets, inverted and micropyle is on lower side. Further, micropyle and funiculus lie side by side and, micropyle is close to hilum., In hemianatropous or hemitropous ovule,, nucellus and integuments (i.e., body of ovule) is, at right angles to stalk or funiculus, e.g., in, primulaceae and Ranunculus., In campylotropous ovule, the body of the ovule, gets curved and micropyle is directed, downwards. Further, micropyle is not in line with, chalaza, e.g., in capparidaceae, chenopodiaceae and, cruciferae etc., In amphitropous (amphiboth) type, curvature, is observed both in the body of ovule and embryo, sac. The embryo sac assumes horse shoeshape., e.g., in papaveraceae, alismaceae and butomaceae, etc., Circinotropous is characteristic type of ovule. It, is found in family cactaceae, e.g., Opunita. Here, the ovule straight first, due to more growth on one, side the ovule gets inverted, but this unilateral, growth still continues till the ovule becomes straight, again. In this manner, the funiculus takes a complete, round around the body of ovule.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚőŕŐęśĘŚĽŐň– Ľň– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř–, l, , l, , l, , l, , l, , l, l, l, l, , l, , l, l, l, , l, , l, , l, , l, , On the basis of the quantity of the nucellus ovules, are of two types : tenuinucellate (nucellus is very, small) and crassinucellate (nucellus is massive)., Formation of megaspore (n) from megaspore mother, cell (2n) inside the ovule is called, megasporogenesis., In the hypodermal region of nucellus towards the, micropylar end develops a primary archesporial, cell., The primary archesporial cell divides periclinally, to form outer parietal layer and inner, sporogenous cells., The sporogenous cell functions as megaspore, mother cell (MMC), which undergoes reduction, division to form 4 haploid megaspores., Only one megaspore remains functional and the, other 3 degenerates., The functional megaspore enlarges and divides, thrice to form 8 nuclei., Megaspore is the initial cell or beginning of female, gametophyte or embryo sac., The nucleus of megaspore undergoes divisions and, gives rise to embryo sac or female gametophyte, which is called megagametogenesis., 3 celled egg apparatus towards the micropylar, end, two middle polar nuclei and three antipodals, at the chalazal end constitute the egg apparatus., The three micropylar cells are collectively known, as egg apparatus., One cell is larger and is called the egg or oosphere, and the other two are called synergids., Synergids are shortlived (one of them degenerates, long before fertilization and second after entry of, pollen tube into embryo sac)., These synergids help –, –, In growth of pollen tube towards egg by, secreting chemotropically active substances., –, In nutrition of embryo sac by absorption, and transport of food from nucellus, through their filiform apparatus., Filiform apparatus in the form of finger like, projections from cell wall is present in upper part, of each synergid., The filiform apparatus is useful for the absorption, and transportation of materials from the, nucellus to the embryo sac., Hook like structures help in easy penetration of, pollen tube and liberation of male gamete from, , l, , l, l, l, l, l, l, , l, , l, , 449, , the pollen tube., Egg is the constant feature of embryo sac. It, fuses with one male gamete to form zygote, (syngamy) and hence embryo., The central cell consists of two polar nuclei., Two polar nuclei fuse to form single diploid, secondary nucleus or definitive nucleus., The chromosomal condition of the secondary, nucleus is diploid (2n)., The 3 cells present towards the chalazal end are, antipodal., Polygonum, Allium and Adoxa types of embryo, sacs are 8 nucleated., Oenothera type of monosporic embryo sac, develops from single functional megaspore of, micropylar end (not chalazal)., Oenothera embryo sac is four nucleated having, egg apparatus and a single polar nucleus in, centre. Antipodals are absent., Tetrasporic embryo sac is of 6 types viz., Pepromea, Penea, Fritillaria, Plumbigella,, Plumbago and Adoxa., , Pollination, l, l, l, , l, , l, , l, , l, , l, l, , The transfer of pollen grains from anther to the, stigma is called pollination., This process of pollination occurs only in, gymnosperms and angiosperms., Pollination in angiosperms gererally takes places, at 2celled stage (rarely 3celled stage) of, microspores or pollen, i.e., vegetative cell and, generative cell., If the pollen grains are transferred to the micropyle, of the ovule directly, the pollination is called direct, pollination. eg. gymnosperms., Since the ovules are enclosed in the ovary in, angiosperms, the pollination is called indirect, pollination., Pollination that occurs in closed flowers is called, cleistogamy and the flowers are called, cleistogamous flowers., If the pollination occurs in opened flower, which, expose their sex organs, it is called chasmogamy, and the flowers are called chasmogamous flowers., Pollination is of two types – self pollination and, cross pollination., The transfer of pollen grains from anther to stigma, of same or genetically similar flower is called self, pollination. It occurs always in crops with
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 450, , l, l, l, l, , l, , l, l, l, , l, , l, , l, l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , bisexual flowers, eg wheat, barley etc., Self pollination is a rule in cleistogamous flowers., Self pollination is of two types autogamy and, geitonogamy., Autogamy is the transfer of pollen grains from, anther to stigma of same flower., Homogamy is the process when anthers and, stigma of a bisexual flower mature at the same, time, eg wheat, rice, potato etc., Geitonogamy is the transfer of pollen grains from, the anther to the stigma of a flower present in the, same inflorescence or in the same plant., Geitonogamy occurs between bisexual flowers or, unisexual flowers of the same plant., Geitonogamy is genetically equivalent to self, pollination but ecologically it is cross pollination., Advantages of self pollination are –, –, It maintains the parental characters or purity, of race indefinitely., –, It eliminates bad recessive characters., Disadvantages of self pollination are –, –, Vigour and vitality of the race decreases with, prolonged self pollination., –, Immunity to diseases decreases., –, Variability and adaptability to changed, environment are reduced., In Gloriosa superba, stamens and stigmas are, projected in different directions to prevent self, pollination., In Hibiscus, the essential organs are placed at, different levels to prevent selfpollination., Cross pollination or allogamy is the process when, pollens are transferred from anther to stigma of, different flower on different plant. It is also called, xenogamy., Dichogamy, dicliny, herkogamy, heterostyly and, self sterility are the main reasons or adaptations, for cross pollination in bisexual flowers., Dichogamy is the condition of bisexuals flower in, which male and female reproductive parts mature, at different times., Dichogamy is of two kinds – protandry and, protogyny., When the androecium matures earlier than, gynoecium, it is called protandry and the flowers, are called protandrous. Eg : Clerodendron,, Saxifraga, Phlox, Asteraceae, Gossypium., , l, , l, l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , When gynoecium matures earlier than, androecium it is called protogyny and the flowers, are described as protogynous. Eg : Solanum., Scrophularia, Helliborous., The phenomenon of production of unisexual, flowers is called dicliny or unisexuality., In maize the male flowers and female flowers are, present in the same plant at different regions., Plants with both kinds of flowers are called, monoecious plants., When two types of unisexual flowers are present, on two different plants, this condition is called, dioecious., Here the male plant bears staminate flowers, and, female plant bears pistillate flowers, e.g., papaya,, hemp, Asparagus, date palm, spinach, etc., When some physical barrier is present between male, and female reproductive parts of a flower which, prevent selfpollination, is called herkogamy, eg., in Calotropis, gynostegium disc is such barrier., Dichogamous flowers are structurally bisexual, and functionally unisexual hence cross pollination, takes place., Occurrence of styles of different lengths is called, heterostyly. It was first discovered by Darwin., Heterostyly is of two kinds – diheterostyly, (occurrence of styles of two different lengths) and, triheterostyly (occurrence of styles of three, different lengths)., Cross pollination occurs between the stamens and, styles of equal length, eg. Lythrum, Biophytum,, Oxalis., When the pollen of the flower reach the stigma of, the same flower, pollen grains do not germinate, and the phenomenon is called selfsterility (self, incompatibility). Eg : Malva, Abutilon and, Passiflora., When the selfpollen and the foreign pollen are, deposited on the stigma, the foreign pollen, germinates quickly and completes fertilization and, the phenomenon is called pollen prepotency. Eg., members of leguminosae (Dolichos, Pisum)., The expression of relationship between the agent, and structure of flower is called pollination, mechanism., For cross pollination, agent is a must.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚőŕŐęśĘŚĽŐň– Ľň– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , Ø, , Ø, , Ø, , Ø, , Ø, , Ø, , Some other mechanism of pollination, Mimicry Male wasp of Calpa aurea visits the, flowers of Ophrys mistaking them as female wasps, and pollinate them., In Salvia (Sage plant), a number of family labiatae,, pollination occurs by bees and there is a special, mechanism called “Turn pipe mechanism” or, “Lever mechanism” of pollination., ‘Fly trap mechanism’ of pollination occurs in, Aristolochia. Flies are attracted by foulrotten, tobacco like odour., ‘Trap door mechanism’ of pollination occurs in, Ficus species (having hypanthodium, inflorescence)., In orchid (Ophrys speculum) pollination occurs by, act of pseudocopulation by the wasp called Colpa, aurea. Appearance and odour of Ophrys is similar, to female wasp and hence male wasps are mistaken, and they land on Ophrys flowers to perform act of, pseudocopulation and thus pollination takes place., This plantinsect relationship is useful only to plant., In Yucca, pollination occurs by a moth called, Tageticula. There is obligate symbiotic, relationship between Yucca and moth, Tageticula, (i.e., this moth cannot complete its life cycle, without association of Yucca and Yucca has no, other pollinator)., , l, , l, l, l, , l, , l, l, l, , l, , Abiotic, Biotic, * Anemophily, * Entomophily (by insects), (by wind) eg. Palm., eg. Aristolochia, Salvia (bee), , l, , * Hydrophily, (by water), eg. Vallisneria, , l, , * Chiropterophily (by bats), * Malacophily, (by snails & slugs), eg. aroids, * Myrmecophily (by ants), eg. rubiaceae., l, , Advantages of cross pollination are –, –, It induces genetic recombination and hence, variation in progeny., –, It increases the adaptability of offsprings., –, Plants produced are more disease resistants., –, New and more useful varieties are produced., , Disadvantages of cross pollination are –, –, A factor of chance is always involved., –, Some undesirable characters may creep in the, race., –, It is a highly wasteful process as large number, of pollen grains have to be produced., , Fertilization, , Agents of cross pollination, , * Ornithophily (by birds), eg. Bombax, Bauhinia (by, humming birds), , 451, , l, l, , l, l, l, , The fusion of male gamete with female gamete, (egg) is called fertilization., The phenomenon of fertilization was first, reported by Strasburger (1884) in Monotrapa., The male gametes are brought to the egg containing, female gametophyte by a pollen tube, the, phenomenon is known as siphonogamy., The pollen tube eats its way through the solid part, of the stigma and style by secreting pectinase and, hydrolytic enzymes., In angiosperms the female gametophyte is seated, deep in the ovarian cavity quite away from stigma., The partially developed male gametophytes (pollen, grains) are normally held at the stigma., To effect fertilization the pollen grains germinate on, the stigma by putting forth pollen tube which grows, through the style and reach the ovules where they, discharge the male gametes in the vicinity of egg., Fertilization occurs in four steps. viz, –, Germination of pollen on stigma, –, Growth of pollen tube, –, Pollen tube entry into embryo sac, –, Fusion of gametes., The first requirement for pollen to germinate is, their hydration which takes from a few seconds to, a few minutes., Pollen absorbs secretion of stigma (sugar, gum,, resins and other liquid) and swells up. Exine ruptures, and intine comes out in the form of pollen tube., Secretion of stigma is sticky and also prevents, pollen as well as stigma from desiccation., The stigmas which secrete exudates are called wet, stigmas (Petunia) and those which do not are called, dry stigmas (cotton)., The pollen tubes pierces through stigmatic papilla, into tissue of style., Styles are of three types – open, half closed and, closed., Open style is hollow and pollen tubes creep on the, surface of special cells lining the stylar canal, e.g.,, papaveraceae and most monocots.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 452, , l, l, , l, , l, l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , In halfclosed style, the canal is surrounded by a, rudimentary transmitting tissue, e.g., cactaceae., In closed style, no open canal is present but instead, a solid core of elongated cells with rich protoplasm,, through which pollen tube moves is present, e.g.,, Datura, cotton., The pollen tube enters the ovule in either of 3, ways –, –, The process of entry of pollen tube through, micropyle is called porogamy, eg. angiosperms., –, The process of entry of pollen tube into the, ovule through chalaza is called chalazogamy,, eg. Betula, Casuarina., –, The process of entry of pollen tube through, integuments or funiculus is called mesogamy,, eg. Cucurbita (through integuments) and, Pistacia (through funiculus)., The pollen tube always enters the embryo sac at, the micropylar end., Inside the embryo sac, one male gamete fuses with, the egg to the form zygote (2n), the process is, known as syngamy or generative fertilization., The second male gamete fuses with 2 polar nuclei, or secondary nucleus to form triploid primary, endosperm nucleus, the process is known as triple, fusion or vegetative fertilization., The zygote develops into embryo and primary, endosperm nucleus develops into endosperm., The occurrence of syngamy and triple fusion, simultaneously in angiosperms is called double, fertilization., Double fertilization was first reported by S.G., , l, l, l, l, , Endosperm and Embryogeny, l, l, , l, , l, l, , l, l, , Table : The transformation of part of flower, Before fertilization, , After fertilization, , Calyx, Corolla,, Androecium, style, Stigma, Ovary, Ovary wall, Ovule, Integuments, Outer integument, Inner integument, Micropyle, Funicle, Nucellus (persistent), Egg cell, Synergids, , Wither, l, , Fruit, Pericarp, Seed, Seed coats, Testa, Tegmen, Micropyle, Stalk of seed, Perisperm, Zygote (oospore), Disintegrate and disappear, , Nawaschin (1898) in Fritillaria and Lilium., Polyspermy is the process when more than 2 male, gametes reach inside a single embryo., Egg may be fertilized by more than one male gamete, to form polyploid zygote., The extra male gametes fuse with synergids or, antipodals to give rise to polyembryo., When egg is fertilized with male gamete of one, pollen tube and polar nuclei are fertilized by male, gamete of other pollen tube, the phenomenon is, called heterofertilization., , l, , l, , Post fertilization changes in plants involve, embryology and endosperm formation., In angiosperms, the zygote develops into an, embryo simultaneously with the development of, the endosperm., Fertilized egg is known as zygote (2n), which gives, rise to embryo after predetermined mode of, divisions. This process of development of embryo, is called embryogenesis., Endosperm is the nutritive tissue which provides, nourishment to the embryo in seed plant., In angiosperm, endosperm tissue is triploid (3n)., It is a product of triple fusion, a result of a fusion, of two polar nuclei (n+n) and one of the male, gametes (n) involving double fertilization., No endosperm is formed in members of families, orchidaceae, podostemaceae and trapaceae., On the basis of development, endosperm are, mainly of three types –, –, Nuclear type, e.g., Cocos nucifera, Primula,, Mangifera, Malva, –, Cellular type, e.g., Adoxa, Peperomia,, centranthus,, –, Helobial type, e.g., Eremurus (liliaceae)., Nuclear endosperm is the most common type of, endosperm found in angiosperms and is reported, in 161 families out of 288 for which record is, available., In nuclear endosperm first and further divisions of, primary endosperm nucleus are not followed by, cytokinesis or wall formation and thus these free, nuclear divisions lead to formation of a large, number of free nuclei in embryo sac. At maturity,, centripetal wall formation (from periphery towards, centre) may occur to make the tissue partly cellular., In cellular endosperm first and further divisions
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ☻ĚőŕŐęśĘŚĽŐň– Ľň– ◘ńŐţĚŕĽňĹ– ▓ńďňŚř, , l, l, , l, l, , l, , l, l, , l, l, l, l, l, l, l, l, l, , l, l, l, , of primary endosperm nucleus are accompanied by, cytokinesis or wall formation and thus the, endosperm tissue is completely cellular. It is, reported in about 72 families of angiosperms, (mostly dicots)., Helobial endosperm is restricted largely to the, monocotyledons., In helobial endosperm the primary endosperm, nucleus moves to the chalazal end of the embryo sac, where it divides forming a large micropylar chamber, and a small chalazal chamber. In the micropylar, chamber, as a rule, freenuclear divisions and cell, formation, if any, start at a much later stage. In the, chalazal chamber the nucleus either remains, undivided or divides only a few times. If later is the, situation, the divisions are usually freenuclear., Endosperm of coconut is unique in sense that it is, both nuclear and cellular., When surface of endosperm is uneven or having, ridges and furrows it is called ruminate, endosperm, eg. rubiaceae., When the tissue of endosperm is not homogenous,, but there are patches of different colours, it is called, mosaic endosperm, eg. Zea mays., Endosperm is generally triploid but it is 2n in, Oenothera, 9n in Pepromea, 5n in Fritillaria., Seeds without endosperm are called, exalbuminous seeds or nonendospermic seeds,, eg. pea, gram., Seeds with endosperm are called endospermic or, albuminous seeds, eg. wheat, rice., A dicot embryo has an embryonal axis and 2, cotyledons attached to it laterally., Epicotyl is the portion of embryonal axis above, the point of attachment of cotyledons., Hypocotyl is the portion of embryonal axis below, the point of attachment of cotyledons., Plumule is at the terminal end of epicotyl., Hypocotyl at its end bears radicle., Monocot embryos have single cotyledons., Seeds are matured ovules., Integuments of ovules forms seed coat, outer, integument forms testa and inner integument forms, tegmen., Fertilized ovary is called fruit., In angiospermic plant, there are 2 phases in life, cycle – the sporophytic and gametophytic., The sporophytic and gametophytic phase alternate, , 453, , with each other in a definite sequence, the process, is called alternation of generation., , PARTHENOCARPY, APOMIXIS AND, POLYEMBRYONY, l, l, l, l, , l, , l, l, l, , l, , l, , l, l, l, , l, , Development of fruits without fertilization is, called parthenocarpy., The term parthenocarpy was coined by Noll (1902)., The parthenocarpic fruits are seedless. Eg. banana,, guava, apple, pineapple etc., Parthenocarpy can be induced artificially by –, –, Spraying auxins (applied after anthesis) and, gibberellins (applied at anthesis), –, Delayed pollination, –, Use of foreign pollen grains, –, Use of powdered pollens and pollen extracts, –, Cutting style from base and applying chemical, like IAA, IBA etc. in lanolin paste at cut, surface., The substitution of sexual reproduction by asexual, process, a form of reproduction which does not, involve syngamy and meiosis is called as, apomixis., The term apomixis was given by Winkler (1908)., Apomixis occur by vegetative reproduction, (described earlier also) and agamospermy., Agamospermy is of threee types – recurrent, apomixis, adventitive embryony and non, recurrent agamospermy. (See flow chart on page, 455)., The archesporium develops inside the nucellus of, ovule which gives rise to megaspore mother cell,, which directly develop into diploid embryo sac., This phenomenon is called diplospory., The phenomenon of having more than one, embryo is called polyembryony, eg. onion,, groundnut., Occurrence of polyembryony due to fertilization of, more than one egg is called simple polyembryony., Formation of extra embryos through sporophytic, budding is called adventive polyembryony., Polyembryony was first discovered by, Leeuwenhoek (1719) and was confirmed later by, Schnarf (1929)., Polyembryony phenomenon is more common in, gymnosperms than angiosperms. In angiosperms,, it is generally present as unusual feature except, few cases like Citrus, mango etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 454, , ŕďőĽę– ĐĽŐńŐĹť–, , Types of Apomixis, Vegetative reproduction, There is no requirement ofseed for production of, new plant., New plant is produced from buds, leaves & stem., Recurrent Apomixis, A diploid (2n) embryo sac is, formed having diploid egg cell, which grow into diploid embryo., E.g. apple, Allium., , Diplospory, Diploid, megaspore, mother cell, , l, l, l, l, , l, , Apospory, Diploid, nucellar, mother cell, , Agamospermy, Embryo & seeds are produced without, involvement of fertlization and meiosis., , Adventitive embryony, When one or few extra embryos are, formed from a diploid cells of, nucellus or integument but never, from egg. Eg Citrus, Opuntia., , Apospory, form, (Sporophyte, Gametophyte), directly, Aposporous formed gametophyte are, generally diploid, Apospory leads to polyploidy formation, Hence new species in pteridophytes &, bryophytes., , There are two types of polyembryony such as, false and true polyembryony., In false polyembryony more than one embryos arise, in different embryo sacs in the ovule., In true polyembryony, more than one embryos, are formed in the same embryo sac in the ovule,, The cause of polyembryony may be –, –, Cleavage of proembryo, e.g., family, orchidaceae,, –, Development of many embryos from other, cells of embryo sac except egg, e.g.,, Argemone, –, Formation of many embryos due to presence, of more than one embryo sac in same ovule,, e.g., citrus, –, Formation of many embryos from the structure, outside the embryo sac, (adventitive, polyembryony), e.g. mango, Opuntia., A special and interesting case of polyembryony is, , l, l, , l, , l, , l, , NonRecurrent Apomixis, Embryo developed, Parthenogenetically from, haploid egg, synergid,, antipodal cells., , Apogamy, form, (Gametophyte, Sporophyte), directly, No gametic fusion involved., Such sporophytes are not viable, if produced from haploid, gametophytes., , found in Allium odorum, where 5 embryos develop, by different methods, e.g., 1 ® Zygotic, 1 ®, synergidal , 2 ® from antipodals, and 1 ® from, integuments., Maximum number of embryos, i.e., 40 are, reported inside single seed of Citrus unshiu., Polyembryony is practically important because, genetically uniform parental type seedling are, obtained from nucellar embryos., Nucellar embryos are superior to those obtained, by vegetative propagation because nucellar, embryos seedlings are disease free and maintain, their superiority for long time., Most important theory of cause of polyembryony, is necrohormone theory given by Haberlandt, (1921), i.e., a stimulus for polyembryony is provided, by degenerating cells of nucellus., Parthenogenesis is the formation of embryo from, the unfertilized female gamete.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 455, , ▓ńďňŚ– ◙ŕŐţŚĺ– ·– ▐ŐŢĚŇĚňŚ, , Chapter 47, , Plant Growth and Movement, PLANT GROWTH AND DEVELOPMENT, l, l, l, , l, l, , l, l, l, l, , l, , l, l, , l, l, , Growth is irreversible increase in dry weight, size,, mass or volume of a cell organ or organism., Growth is intrinsic in living beings., The growth that take place between seedling, emergence and flower initiation in a plant is called, vegetative growth., Vegetative growth takes place in vegetative parts, of the plant., Reproductive growth constitutes initiation of, flowering, development of sex organs, fertilization, and seed formation., In multicellular plants growth is restricted to some, specific region (called meristems)., The growing region in plants are apices of shoot, and root where meristems are present., Meristems are classified into 3 types apical,, lateral and intercalary., The apical meristem is terminal in position and is, responsible for apical growth of plant, e.g., shoot, and root apices., Lateral meristem is responsible for lateral, growth or secondary growth that increase the, thickness of plant., The intercalary meristem is responsible for, localized growth of plant, eg., in bamboo and mint., Plant growth takes place in three steps , –, Formative phase or cell division phase (cells, of apical meristem divide)., –, Enlargement phase or cell elongation phase, (proteins, protoplasm, cell wall material is, synthesized)., –, Differentiation phase or cell maturation, phase (secondary walls are laid down)., The primary work on growth measurement was, done by Sachs (1873)., When rate of growth is plotted in terms of length, size,, , l, l, l, l, , l, , l, , l, , area, volume or weight, growth curve is obtained., The rate of growth is represented against definite, period of time., S shaped or sigmoid growth curve is exhibited by, numerous annual plants., The period during which the growth shows, increase is called grand period of growth., There are three primary phases which can be detected, in a growth curve – lag phase (or slow phase), log, phase (or exponential phase) and steady phase., In lag phase, the growth is slow, the growth increase, during log phase and become steady or constant in, steady phase., The various methods for measurement of, growth in terms of increase in weight or length or, volume are – direct method in which growth is, measured directly by a scale at regular intervals, from beginning to end, horizontal microscope or, travelling microscope, Bose crescograph,, auxa nomete r (arc auxan ometer, pfeffer’s, auxanometer), space marker disc., The various factors that affect the growth are –, food supply, water supply, oxygen supply,, temperature, lightintensity, quality and duration,, and growth hormones., Growth, , In unicellular plants, , In multicellular plants, , growth is over all, not restricted to a region, , growth is restricted to, some specific regionģ, ţ˚†π‡•˚‚, , Apical, meristem, , Intercalary, meristem, , Lateral meristem, or cambium, , divide radially,, eg. at base of nodes, eg. at root & shoot, response for, apex for growth or internodes, responsible, secondary growth, for increase in length, in length
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 456, , l, l, l, l, l, l, , l, l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Water, oxygen and nutrients are very essential, element for growth., Plant cells grow in size by cell enlargement which, in turn requires water., Turgidity of cells helps in extension growth., Water also provides the medium for enzymatic, activities needed for growth., Oxygen helps in releasing metabolic energy, essential for growth activities., Nutrient (macro and micro essential elements) are, required by plants for the synthesis of protoplasm, and as source of energy., Every plant organism has an optimum temperature, range best suited for its growth., Environmental signals such as light and gravity also, effects certain phases/stages of growth., The cells derived from root apical and shoot apical, meristems and cambium differentiate and mature, to perform specific functions. This act leading to, maturation is termed as differentiation., During differentiation, cells undergo few to major, structural changes both in their cell walls &, protoplasm., The living differentiated cells, that by now have lost, the capacity to divide can regain the capacity of, division under certain conditions, the phenomenon, is termed as redifferentiation., Development is a term that includes all changes, that an organism goes through during its life cycle, from germination of the seed to senescence., Meristematic, cell, , Cell, division, , Plasmatic, growth, , Differentiation, , l, , l, , l, , l, , l, , l, , Cell elongation, Cell maturation, l, , Cell death, , Senescence, , Mature cell, , Photoperiodism, l, , l, , l, l, , Photoperiodism is the response to durational and, timings of light and dark periods in terms of, flowering., It was first studied by W.W. Garner and H.A., Allard (1920) in Mary land Mammoth (mutant, variety of tobacco)., The hours of light that a plant has been exposed is, called photoperiod., The length of uninterrupted photoperiod that has, , l, , to be always exceeded in long day plants and must, not exceed in short day plants is called critical day, length, eg. Xanthium is a short day plant and its, critical length is 15 hrs i.e. below 15 hrs flowering, will take place., Depending on the length of photoperiod require, ment for flowering, the plants are classified into–, (a) short day plants, (b) long day plants, (c) day, neutral plants, (d) short long day plants, (e) long, short day plants, and (f) intermediate plants., Short day plants (SDP) or long night plants are, those plants where flowering take place when they, are exposed to shorter photoperiod, i.e, day length, is less than the critical length, for eg. Maryland, Mammoth tobacco (Nicotiana tobaccum) Xanthium,, Crysanthemum, rice, sugarcane, potato, soyabean, (Glycine max), Aster, Dalhia etc., Long day plants (LDP) or short night plants are, those plants where flowering takes place when they, are exposed to longer photoperiod i.e., more than, critical day length, for eg. spring barley, sugarbeet,, henbane (Hyoscyamus niger), wheat, radish, oat,, spinach, lettuce etc., Day neutral plants or day length indifferent, plants are those plants where day length does not, influence flowering. These plants flower in both, shorter and longer photoperiod, for eg. maize,, cotton, tomato, cucumber, sunflower, pepper etc., Short long day plants (SLDP) require short, photoperiod for initiation of flowering and long, photoperiod for blossoming, eg. Trifolium repens., Long short day plants (LSDP) require long, photoperiod for initiation of flowering and short, photoperiods for blossoming, eg. Bryophyllum,, Cestrum., Intermediate plants (IP) flower within a definite, range of photoperiod, eg. wild kidney bean., Phenomenon of producing photoperiod influence, on the production of flower is photoperiodic, induction or photoinduction., , Phytochrome, l, , l, l, , The pigment that played a role in seed germination, in Letuca sativa, was named phytochrome by, Butler., Phytochrome is glycoprotein in nature with a light, absorbing portion called chromophore., Phytochrome in plants occur in two inter
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ◙ŕŐţŚĺ– ·– ▐ŐŢĚŇĚňŚ, , l, , convertible forms namely Pr (P680) and Pfr (P730)., Pr form of pigment absorbs red light and Pfr form, of pigment absorbs far red light. Two forms can, be represented as — Pr, , l, l, , l, , l, , red light, , far red light, , Pfr ., , The Pr form is inactive and Pfr is the active phase, of the pigment related to photomorphogenesis., Pfr form is needed for flowering in LDP and seed, germination and Pr form helps in flowering of, SDP., Phytochrome is widely distributed and is associated, with membrane. It is found in angiosperm,, gymnosperms, bryophytes, some green algae, red, algae and brown algae., Different phytochrome activities are flowering,, elongation of leaf, stem petiole, development of root, rhizome, bulb, germination of pollens, unfolding, of hypocotyl hook and grass leaf, differentiation of, stomata & tracheary elements., , Vernalisation, l, l, l, l, l, , l, l, l, l, , Low temperature induction of flowering is called, vernalization., In vernalization, by cold treatment winter varieties, are transferred into spring or summer varieties., The stimulus for vernalization is perceived by, buds, meristems, seeds, seedlings & even embryo., Nullifying the effect of vernalisation is called, devernalisation., German plant physiologist George Melchers, (1937) has proposed the existence of a stimulus of, vernalisation and coined it a vernalin., Vernalisation help in shortening the vegetative, period of plant. It prepares the plant for flowering., Vernalisation increases yield, resistance to cold, and diseases., Gibberellins, a plant hormone can replace the, requirement of vernalisation., Florigen (a flowering hormone) is synthesized in, older leaves and then transferred to flowering, region. It initiates the floral bud initiation., , Seed germination, l, , l, , Seed is fertilised and ripened ovule which contains, a dormant embryo, reserve food for its future, development and protective covering., The formation of seedling from dormant embryo, of seed after resumption of its active growth, is, called germination, or in other words the activation, , 457, , and growth (rejuvenation) of the embryo into a, seedling during favourable conditions is called, germination., Physical and physiological changes during, germination, l, First physical process during germination is, absorption of water by imbibition., l, First biochemical reaction during germination is, hydrolysis of reserve food., l, In cereals and millets reserve food (carbohydrate), is hydrolysed by amylase., l, In pulses, reserve food (protein) is hydrolysed by, proteases., l, In oil seeds like coconut, castor etc reserve food, (fat) is hydrolysed by lipase., l, In the presence of water enzymes are activated., l, By the action of hydrolytic enzymes, complex, reserve food materials are degraded and converted, into simple, soluble, osmotically active substances., The embryo absorbs these simple food substances, and grow in size by repeated cell division., l, Meanwhile the seed coat ruptures and the growing, embryo is exposed to air and light., l, Rate of aerobic respiration increases rapidly and, cells of the primary axis (of the embryo) synthesize, proteins and DNA., l, Newly formed cells elongate rapidly., l, Radicle emerges out of the seed first and develops, into root system. Due to elongation of hypocotyl, region the plumule comes above ground and later,, develops into shoot system., l, First structure that comes out during germinations, is radicle., l, Respiration rate is increased in germinating seeds., Types of seed germination, l, Germination is basically of two types depending, upon behaviour of cotyledons, these are epigeal, and hypogeal., l, When due to hypocotyl growth or elongation,, cotyledons are pushed out of soil, the germination, is called epigeal germination., l, Epigeal germination is seen in legumes, cucurbits,, Ricinus etc., l, When due to epicotyl elongation, plumule comes, out of the ground and cotyledons remain, underground, the germination is called hypogeal, germination.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 458, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Hypogeal germination is seen in cereals, millets,, grams, coconut, Mangifera etc., Germination of seed before dispersal is called, ‘vivipary’ (or) in situ germination., Vivipary is a characteristic feature of mangroves,, eg., Rhizophora, Avicennia etc., , Factors affecting seed germination, l, Seed germination is directly affected by many, external (environmental) and internal, (physiological) factors., l, External factors – Among many external factors, that affect seed germination water, temperature,, oxygen and light are important., l, Water, –, Seeds are the driest structures of the plant,, they contain minimum amount of water., –, Water activates the enzymes which digest the, complex reserve foods of the seed., –, It maintains the turgidity of the embryonal, cells and helps in cell elongation., –, It helps in the rupturing of the seedcoat., –, It is the medium for all physiological, processes., –, If the water content of the seed goes below a, critical level, seeds fail to germinate., l, Temperature, Seeds fail to germinate at very low and high, temperatures. Low temperature inactivates the, enzymes and high temperature denatures the, enzymes. The optimum temperature for seed, germination varies from plant to plant. A, temperature range of 15º 30ºC is favourable for, germination in most plants., l, Oxygen, Oxygen is highly essential for germination. In, the beginning, germinating seed respires, anaerobically. When the seed coat ruptures, the, embryo is exposed to air and carries on aerobic, respiration at a higher rate. In the absence of O2, oxidation of food materials is stopped and the, embryo fails to grow., l, Light, –, Seeds of most of the plants usually do not, require light for germination. However, seeds, of epiphytes, Ficus aurea, Digitalis purpurea,, Salicoira, Nicotiana, Rumex, Viscum, (mistletone) poa grass etc., require light for, germination., , –, , l, , Seed which germinate only in presence of, light, are called photoblastic seeds., Internal factors – The important internal factors, which interfere with seed germination are :, –, Seed viability – The capacity of a seed to, germinate and develop into a seedling is called, seed viability. The viability of seeds varies in, different plants. It depends on the method of, storage, healthiness of the parent, age of, the seeds, maturity of the seeds etc., –, Longest seed viability is reported in, Nelumbo nucifera (= Nelumbium speciosum), or Indian lotus (Kamal)., –, Seed vigour – The ability of a seedling to, establish itself in the soil and lead independent, life is called seed vigour or germinating vigour., –, Completion of seed dormancy Many seeds, require a dormancy or resting period after, harvesting and germinate only after resting, period., –, Food availability Sufficient amount of food, is required for growing embryo., –, Maturity of embryo., , Seed dormancy, l, , l, , Seeds of some plants like rice, maize, germinate, immediately after reaching the ground. Seeds of, Citrus and Rhizophora show vivipary. But in, majority of plants seeds remain in an inactive state, and germinate only after a specific period of rest., Such inactive state is called dormancy or, quiscence., Dormancy may be defined as “the inactive state, of the seed in which growth of the embryo is, temporarily suspended for a specific length of, time.”, , Causes of dormancy, l, Tough and thick seed coats, Seed coats of some plants like mustard, shephard’s, purse, Lepidium (pepper grass) etc., are very tough., The growing embryo fails to emerge out due to the, resistance of the thick seed coat. Therefore, such, seeds remain dormant until their seed coats become, soft and thin due to ageing., l, Impermeable seeds coats, Seed coats of some plants are thick and impermeable, either to water (seeds of Malvaceae, Leguminosae,, achenes of Nelumbium) or oxygen (seeds of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 459, , ▓ńďňŚ– ◙ŕŐţŚĺ– ·– ▐ŐŢĚŇĚňŚ, , l, , l, , l, , l, , Compositae Xanthium). As a result seeds remain, dormant. In nature, such seed coats become soft, and permeable due to microbial action and, fluctuations of temperature and moisture., Immature (rudimentary) embryos, In some orchids, the seed contains an immature or, incompletely developed embryo, at the time of, shedding. Immature embryo may be in the zygote, stage or a few celled proembryo stage. Such seeds, germinate only after the embryo completes its, development., After ripening effect, Seeds of apple, peach etc., contain fully developed, (mature) embryos by the time they are shed. But, these seeds fail to germinate even if favourable, conditions are provided. Dormancy of this type is, due to physiological immaturity of the embryo. Such, seeds undergo ‘after ripening’ in nature and then, only germinate., Dormancy due to light requirement, Photoblastic seed, eg, lettuce, donot germinate in, absence of light., Germination inhibitors, Seeds of some plants like tomato fail to germinate, due to the presence of growth inhibitors like, abscissic acid (ABA), caffiec acid, ferulic acid,, coumarins etc. These inhibitors prevent the, germination of the embryo. In nature, these, inhibitors are gradually washed off from the seeds., , Methods of breaking domancy, l, Mechanical scarification : Mechanical rupturing, of seed coat., l, Chemical scarification : Weakening of seed coat, by acid, water, solvents etc. Dormancy can be, broken by treating the seeds with strong acids, (H2SO4) or dipping in boiling water or rubbing on, a rough surface. This is called chemical, scarification., l, Chilling treatment – Seeds are stored at low, temperatures (0º 10º C) for two three months in, open places in alternate layers with sand. This is, called stratification, eg., Peach, Cherry., l, Counteracting inhibitors – Dormancy can be, broken by soaking seeds in KNO3 thiourea, repeated, soaking and washing of the seeds in water. Plant, hormones like gibberellins also break this type, of dormancy., , Vigorous shaking, Exposure to red light – It induces germination in, lettuce., Providing high pressure – 2000 kg for 5 – 20 mins., , l, l, l, , Seed certification, Ø, , Ø, Ø, , Good seed always gives better yield. Selection of, good seeds is an important aspect of present day, agriculture. Modern plant breeding techniques also, aim at producing quality seed. Seeds that give rise, to high yielding, disease and drought resistant, early, maturing plants are called quality seed. Quality of, the seed determines the yield. The qualities of better, seed are :–, –, High rate of germinating vigour, –, Short duration of the crop, –, Disease resistance, –, Pest resistance, –, Limited vegetative growth, –, High yield., In order to supply such seed to the farmers, Central, Seed Certification Agency was started in 1966., Andhra Pradesh state seed certification agency, classified the seeds into four types depending on, the generation of the seed – breeder’s seed,, foundation seed, registered seed and certified seeds., , Senescence, l, , l, , l, , l, l, , l, , Senescence is the stage in the life history of an, individual when the rate of metabolic activities, decline that leads to ageing and then eventually, death., Plant senescence is of four types , –, whole plant senescence, –, shoot senescence, –, sequential senescence, –, simultaneous or synchronous senescence., Whole plant senescence is found in monocarpic, plants where flower and fruit formation take place, only once in their life cycle, eg. rice, wheat., In shoot senescence, aerial organs die but, underground organs survive, for eg. Gladiolus., In sequential senescence, senescence of organ, continues throughout the year. The older leaves and, lateral organs show senescence and die, for eg., mango, Eucalyptus., In simultaneous senescence, shedding of leaves, take place in autumn, for eg. Maple, elm.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 460, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Senescence occurs in nonmeristematic cells, and, meristematic cells donot undergo senescence., Abscission is the natural shedding of leaves from, the plants without any response to injury, but due, to change in hormonal balance., Abscission zone is the special narrow zone that, develops in the area of abscission., Two distinct layers develop in the abscission zone, are– separation layer (upper layer) and protective, (lower layer)., , l, , l, , l, l, , PLANT MOVEMENT, l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, , l, , l, , The capacity of plants to change their position in, response to external or internal stimuli is known as, plant movement., Stimulus is the any change in the environment of, an organisms or of part of it which is intense enough, to produce a change in the activities of the living, material, without itself providing energy for the new, activities., Stimulus is defined by Verworn., Sensitiveness to stimulus is called irritability., The specific region or site where the stimulus is, received for changing position is called perception, site., The minimum period for which stimulus should be, given for inducing plant movements is called, presentation time., Conditions that are necessary for plant, movements are water, temperature, oxygen,, hormones, nonfatigued tissue or organ., There are two broad kinds of movements of, plants – movements of locomotion and, movements of curvature., Movement of whole organisms or cellular, constituents is referred to as movement of, locomotion., The two types of movements of locomotion are–, spontaneous (or autonomic) and paratonic (or, induced or tactic)., Spontaneous movements of locomotion occurs, due to internal cause and are without any influence, of external stimuli., Common spontaneous movements of locomotion, are – ciliary or flagellar movements, amoeboid, movements, cyclosis or streaming of protoplasm,, excretory movement., Movements of mobile algae, gametes and zoospores, , l, , l, , l, l, , l, , l, , l, l, l, l, l, l, , l, , having cilia or flagella takes place automatically, and are known as ciliary movements., Movements that can be observed in the plasmodia, of slime moulds (Myxomycetes) are amoeboid, movements., Cytoplasm of eukaryotes show perpetual, locomotion called cyclosis or streaming, movement., Cyclosis is of two types rotation and circulation., Cyclosis around a single central vacuole in, clockwise or anticlockwise direction is rotation,, eg. observed in leaf cells of Hydrilla and Vallisneria., Cyclosis around many vacuoles of a cell in, clockwise or anticlockwise directions is called, circulation, eg., in staminal hair of Tradescantia, and shoot hair of gourds., In Oscillatoria, apical part shows oscillation due, to excretions of some substances. This type of, movement is called excretory movement., Induced movements of locomotion are due to, external causes or stimuli., Depending on the nature of stimulus, taxis or, tactic movements may be chemotaxis (when, influenced by chemical substances), phototaxis, (when influenced by light), thermotaxis (when, influenced by temperature)., Chemotaxis is locomotory movements in response, to presence of chemicals, e.g., spermatozoids, towards sucrose, malic acid in archegonia of moss, and fern., Phototaxis is a locomotion in response to direction, and intensity of light, like small algae moving, towards moderate light., Chloroplast present in palisade cells of higher plants, also move in accordance with the intensity of light., Movement of motile algae from cold water to, slightly warm water is thermotactic in nature., Movement of plant parts in relation to others are, called movements of curvature., Movement of curvature are caused by unequal, growth in different parts of plant., Movements in curvature are mechanical and vital., Mechanical movements take place in the non living, organs of the plant. Such movements are possible, due to the imbibition of water (hydrochasy, eg., spore dispersal in moss) or loss of water, (xerochasy, eg. bursting of explosive fruits)., Vital movements are observed in living part and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ◙ŕŐţŚĺ– ·– ▐ŐŢĚŇĚňŚ, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , are two types spontaneous (or autonomic), paratonic (or induced)., Spontaneous movement of vital movements are, of two kinds – movement of variation and, movements of growth., Movement of variation takes place due to, variation in the turgidity of cells. This type of, movement is exhibited by the pulsation of the two, lateral leaflets of Desmodium gyrans and, movements of leaves of Mimosa pudica., Movement of growth is a slow movement and it, occurs in growing organs due to the difference in, the ratio of the growth of different parts of the, growing organs., Movement of growth are – nutation, epinastic and, hyponastic., Nutation movement is the growth in the apex of, the stem in zigzag manner due to alternate change, in growth rate on opposite side of the apex., A nutational movements may be circumnation, when the apex of the stem makes rotational growth, around its long axis. It is found in stem tip of, twinners., When movements occurs due to faster growth on, the upper side of the organ then it is called epinastic, movement, eg. opening of flower., When the movement occurs due to the faster growth, on the lower surface of the growing organ then it, is called hyponastic movement, eg. closing of, flower, rolling of leaves., Induced movements of vital movements are of, two kinds : tropic or directional, and nastic or, nondirectional., Tropic movement take place under the influence, of unidirectional stimulus and the response may be, related to the direction of the stimulus., Important tropic movements are phototropism,, geotropism, hydrotropism, thermotropism,, thigmotropism and chemotropism., When the tropic movement is induced by, unidirectionally supplied light, then it is, phototropism., If the curvature movement is towards the source, of light, then it is called positive phototropism and, if away from the source of light, then it is called, negative phototropism., The leaves of many plants grow at right angles to the, incident ray, hence they are called diaphototrophic., , l, l, , l, l, , l, l, , l, , l, , l, , l, l, , l, l, , l, , l, , l, , l, , 461, , Root is negatively phototropic and stem is, positively phototropic., Examples of phototropism are flower heads of, sunflower and leaves of Neptunia olearacea that, show movement in accordance with the angle of, the sun i.e., they show movement from east to west., Only blue wavelengths of light are effective in, producing phototropic response., Geotropism is a tropic movement in which, curvature takes place in the stem or the root under, the influence of unidirectional stimulus of gravity., Stem are negatively geotropic and roots are, positively geotropic., When some plants grow horizontally i.e., at right, angle to gravity (for eg. runners, stolons etc.) then, it is called diageotropism., The stem and root branches growing at an angle, of 45° from the vertical axis are termed as, plageotropic or plagiogeotropic, eg. secondary, lateral roots., Thigmotropism is a directional curvature, movement of growth which is produced in response, to stimulus of contact, eg. tendrils of Passiflora,, pea etc., Hydrotropism is directional growth movement of, curvature which is caused by unilateral stimulus of, water., Roots are positively hydrotropic., Chemotropism is a directional paratonic movement, of curvature that occurs in response to chemical, stimulus., Growth of pollen tube is the style, ovary and ovule, is a chemotropic movement., The roots of Lupinus albus show positive, chemotropism with sodium mono hydrogen, phosphate and negative chemotropism with KNO3,, Ca(NO3)2, NH4NO3 etc., Responses which do not have relation with the, direction of stimulus are called nastic movement, or nastic responses., Nastic movements are caused by turgor changes, (swelling or shrinkage of living cells due to change, in osmotic potentials)., Important nastic movements are nyctinasty,, thermonasty, seismonasty, photonasty,, thigmonasty., Nyctinasty movement or sleep movement is induced, by alternation of day and night (diurnal changes).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓坌ŐĺŐŕŇŐňĚř–, , 463, , Chapter 48, , Phytohormones, l, , l, l, , l, , l, , l, , l, , l, , l, , A plant hormone or phytohormone is a chemical, substance produced naturally in plants which is, translocated to another region for regulating one or, more physiological reactions when present in low, concentration., All phytohormones are growth regulators but all, growth regulators are not phytohormones., The same hormone may produce a different, response in different organ as auxin concentration, promotes shoot growth but inhibit root growth., A similar response may be produced by different, plant growth hormones, eg., both auxins and, gibberellins promote cell enlargement., Phytohormones can be broadly divided into two, groups based on their functions in a living plant, body – growth promoters and growth inhibitors., Auxin, gibberellins and cytokinin are growth, promoters and ethylene and abscisic acid (ABA), are growth inhibitors., Growth promoters are involved in growth, promoting activities, such as cell division, cell, enlargement, pattern formation; tropic growth,, flowering, fruiting and seed formation., Growth inhibitors are involved in various growth, inhibiting activities such as dormancy and, abscission and also play an important role in plant, responses to wounds and stresses of biotic and, abiotic origin., The gaseous plant hormone ethylene could fit, either of the groups, but is largely an inhibitor of, growth activities., , AUXIN, l, , l, , F.W. Went first named the chemical substance, ‘auxin’ (means to grow) derived from Greek word, auxein., Auxin is weakly acidic growth hormone having, , l, l, l, l, , an unsaturated ring structure and promotes cell, elongation especially in shoots., Auxins obtained from plant are called natural, auxin., IAA (Indole acetic acid) is a natural auxin obtained, from Rhizopus scinus and Avena coleoptile., Tryptophan is the precursor of IAA and zinc is, required for its synthesis., Many auxins have been synthesized and some, examples of synthetic auxins are indole3butyric, acid (IBA), naphthalene acetic acid (NAA), 2,4, dichlorophenoxy acetic acid (2,4D), 2,4,5, trichlorophenoxyacetic acid (2, 4, 5 T)., Agent Orange, Mixture of two phenoxy herbicides in ester form,, 2, 4D and 2, 4, 5–T (dioxin) is given the name, agent orange which was used by USA in Vietnam, war for defoliation of forests (i.e. in chemical, warfare). Phenoxy agents work by mimicking a plant, growth hormone, 1AA. When sprayed on broad, leaf plants they induce rapid uncontrolled growth, eventually killing them., , l, , l, , l, , l, l, l, , Free auxins are those which are easily diffusible, i.e., they move out of tissues easily, e.g., IAA, indole3, ethanol etc., Bound auxins are those which are not diffusible, and they can be removed from the plant tissues, by the application of some special techniques like, enzymolysis etc., e.g. auxin glycosyl esters., Active sites of auxin synthesis are shoot tip region, and its synthesis occurs rapidly in green leaves, in the presence of light than in dark., Indole acetic acid is destroyed by enzymatic, oxidation and photooxidation., IAA oxidase, an enzyme, which oxidises IAA was, isolated in 1947 by Yang and Bonner., F. Skoog had reported that auxin is inactivated under
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 464, , l, l, l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , the influence of Xrays and gamma radiations and, ultraviolet light brings about inactivation of IAA., Translocation of auxins is polar., Auxin transport is basipetal in stem and acropetal, in roots., Transport of auxin is energy consuming and is, drastically reduced in the absence of oxygen., Compounds that inhibit the polar auxin transport, are called antiauxins. Eg. 2,3,5triiodobenzoic acid, (TIBA), anaphthylphthalamic acid (NPA)., Ethylene (a gaseous hormone) also inhibits auxin, polar transport., The use of living material for testing the effect of, biologically active substances is called bioassays., Avena curvature test (given by F. W. Went) and, split pea stem curvature test are the bioassays, that are generally used for auxins., , Physiological effects of auxin, l, , l, , l, , l, l, , l, , l, , The cell enlargement is induced by auxin by, –, increase in osmotic content of the cell., –, increase in cell membrane permeability to, water., –, reduction in wall pressure., –, synthesis of wall material., –, increase in respiration., –, synthesis of specific RNA and proteins which, result in increase in cell wall plasticity., Auxin initiates and enhances cell division by, inducing meristematic activity and cambial cells, activity., Auxin induce early differentiation of xylem and, phloem in tissue culture experiments., Auxin + 2% sucrose – Xylem–differentiation, Auxin + 3% sucrose – Xylem and phloem, differentiation, Auxin + 4% sucrose – Phloem differentiation, In tissue culture growth of callus requires the, presence of auxin, e.g., 2, 4D., It has been suggested that traumatic acid (wound, hormone) is produced which increases cell division, resulting in callus formation., Auxin causes root initiation but high, concentration of auxin inhibits the root growth, and the number of branches of roots are also, decreased., IBA, a synthetic auxin is a potent root initiator., Other auxins used as rooting agent are NAA, IAA etc., , l, , l, l, l, , l, l, l, l, , l, , l, , l, l, , l, , l, l, l, , Apical dominance or bud inhibition is the, phenomenon of suppression of growth of lateral, buds by apical buds. When apical buds are removed,, lateral buds develop into branches., Apical dominance is due to the presence of high, concentration of auxins in apical buds., Auxin enhances the size of carpel and hence, earlier fruit formation., Hitchock and Zimmerman for the first time, showed that flowering in Nicotiana can be, stimulated by auxin., Auxin increases the number of spikelets in wheat, and flowering in pineapple., NAA induces the formation of more fertile branches, in cotton plants., IAA promotes formation of female flowers, (feminization)., Flowers are borne only on dwarf shoot in apple tree, but NAA increases the number of dwarf shoot and, therefore more flower and fruits are borne., The development of fruit without pollination and, fertilization is called parthenocarpy, and such fruits, are obtained by spraying with dilute solution of IAA, & IBA., Auxins like IAA, IPA, NAA and IBA are, commerically used to induce parthenocarpy in, banana, orange, citrus, grapes, guava etc., Auxin delays abscission of leaves and fruits., 2,4D, NAA, 2,4,5T (2,4,5 trichlorophenoxy acetic, acid), MCPA (2, methyl4 chlorophenoxy acetic, acid) are used as effective weedicides or, herbicides., 2,4D is a selective weed killer as it is toxic to broad, leaved plants and in low concentration it is useful, in preventing preharvest fruit drop of orange and apple., According to CholodnyWent theory auxins are, responsible for phototropism and geotropism., IAA is known to stimulate nodule formation., Few auxins are used to prolonging the life of, storage products like corm, tuber, rhizomes etc.,, e.g. NAAM (Naphthalene acetamide)., , GIBBERELLINS, l, , Gibberellins are weakly acidic plant growth, hormone that possess a gibbane ring structure and, are able to promote cell elongation of the stem,, leaves and also internodal length of genetically, dwarf plant.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 465, , ▓坌ŐĺŐŕŇŐňĚř–, l, , l, , l, , l, l, , l, l, l, l, , l, , They are named after fungus Gibberella fujikuroi, which produces foolish seedling disease of rice or, bakanae disease., Yabuta, Hayashi and Kahnbe first isolated the, active principle toxin secreted by the fungus which, was called gibberellin by them., Chemical nature of Gibberellins was established in, 1954 and till now more than 100 different types of, gibberellins have been isolated., Chemical gibberellins are related to terpenoids and, its precursor is kaurene., Gibberellins are found in angiosperms,, gymnosperms, ferns, algae but rarely in fungi and, bacteria., Sites of gibberellin synthesis are young leaves, (major site), root tips and immature seeds., Gibberellins move readily in all directions and in, all tissues including phloem and xylem., Translocation of gibberellins is passive, non polar, and diffuse type., Techniques used for the bioassay of gibberellins, are – dwarf pea elongation technique, barley, endosperm digestion technique., Compounds that inhibit the action of gibberellins, are antigibberellins or gibberellins retardants., Examples are phosphon D, Amo 1618,, paclobutrazol, cycocel (CCC), maleic hydrazide etc., , l, l, , l, , l, l, , l, , l, , l, , Physiological effects of gibberellins, l, , l, , l, , l, , l, , l, , Gibberellins enhances seed germination by, enhancing amylase synthesis and thus overcomes, dormancy., In the aleurone layer of barley the gibberellins, increase the transcription of genes that code for, protease and amylase enzyme., Gibberellins stimulate conversion of storage, polymers into sucrose or mobile amino acids, during germination to facilitate their translocation, via phloem into and through out the young root and, shoots., The cold treatment which breaks the natural bud, dormancy increases the endogenous level of, gibberellins., Gibberellins play important role in elongation of, internodes in rosette plants (e.g. Henbane,, cabbage) which is called bolting. Flowering takes, place after bolting., Gibberellins causes etiolation (elongation) in, , plants when kept in dark, as flavonoids which are, inhibitors of GA are not formed in dark., Gibberellins induces cell division and cell, elongation when bolting take place., Genetic dwarfism is caused by mutation of a single, gene. If gibberellins is sprayed on these single gene, dwarf plants, genetic dwarfism is overcome and, plants become long, eg. in maize, pea etc., Gibberellins play an important role in the initiation, of flowering in vernalised and long day plants, during short day condition, eg. cabbage., Synthesis of florigen which is a flowering hormone, is mediated through gibberellins., Gibberellins promotes male flowers production, i.e., on female plant, male flowers are produced by, application of gibberellins, e.g., Cannabis., Exogenous application of gibberellins also induces, the production of parthenocarpic fruits., Examples are plants belonging to family rosaceae,, as stone fruits and pome., When gibberellins are sprayed on the plants their, leaves become expanded. It results in an increase, in the total photosynthetic area and biomass., Commercially gibberellins are employed to, –, increase the size of seedless grape fruits,, –, increase the height of sugar cane plant and, thus enhances the yield of sugar., –, used in storage of orange as it prevents rind, disorder by delaying senescence., , CYTOKININS, l, , l, , l, l, , l, l, , Cytokinins are mildly basic growth hormones, which are usually amino purine derivatives and, promote cell division in plants., Miller in 1955 isolated an active substance from, autoclaved DNA from Herring sperms which, stimulated cell division. He named this substance, as kinetin., Chemically kinetin was identified as 6furfurylamino, purine., Zeatin is a naturally occurring cytokinin. Letham, obtained zeatin in pure crystalline form in unripe, maize grains., Zeatin occurs in the roots, stem and leaves but it, is present in abundance in its milk kernels., Synthetic cytokinins are substances that show, cytokinins like activities. The examples are, 6 aminopurine (adenine), benzimadazole,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 466, , l, , l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , 6benzyladenine, 2 ip (isopentanyl adenine)., Beauchene and Bontarel in 1963 prepared a, compound N6isopentanyl adenine which is ten, times more active than cytokinins., Precursors of cytokinin is either adenine or, adenosine., Cytokinins are found in abundance in young roots,, leaves and young fruits and are synthesised in the, meristematic regions of the plants., Translocation of cytokinin takes place through, xylem. Mobility is polar and basipetal., Zeatin, dihydrozeatin and isopentanyl adenine are, physiologically active cytokinin., Some of the bioassays for cytokinins are, –, excised radish cotyledon enlargement test, –, chlorophyll preservation test or delay in, senescence test, –, tobacco pith culture., , l, l, , l, , l, l, l, l, l, , Physiological effects of cytokinin, l, l, l, l, , l, , l, , l, , l, , Cell division activity and cell enlargement is, enhanced by cytokinins., Cytokinins are essential for cytokinesis though, chromosome doubling can occur in their absence., In the presence of auxin, cytokinins bring about, division even in permanent cells., Cytokinins control morphogenesis i.e., control, initiation of plant organs., –, High cytokinins to auxin ratio causes, differentiation of shoot., –, Low cytokinins to auxin ratio causes, differentiation of root., –, Intermediate cytokinins to auxin ratio, causes differentiation of both root and shoot., –, Intermediate cytokinins to low auxin ratio, leads to callus formation., Cytokinins are quite effective in breaking the, dormancy of seeds and some other plant organs., For e.g., seeds of Lectuca sativa., Cytokinins counteract the phenomenon of apical, domimance and it induces lateral bud formation, even in presence of apex., Cytokinins induces plastid differentiation,, lignification of tracheary elements and, differentiation of interfasicular cambium., Cytokinins delay the senescence of leaves and, other organs. It is called Richmond Lang effect, after its discover who worked with detached leaves, of Xanthium., , Cytokinins, like auxins, promote femaleness in, male flowers., Cytokinins enhance chloroplast development and, chlorophyll synthesis. There is increase in rate of, protein synthesis on kinetin treatment., When detached leaves are treated with cytokinins, it leads to delay of degradation of proteins and, chlorophyll., Cytokinins induce flowering in short day plants, like Lemna, Wolffia., Cytokinins influence the physiological properties, of RNA and DNA., Cytokinins help in phloem transport., Cytokinins mobilise solutes and other nutrients., Commericial use of cytokinins (CK) are–, – CK increases shelf life of vegetables and cut, flowers., – CK improves yield and quality of fruits., – A combination of cytokinin (6benzyladenine), and gibberellins (GA4GA7) called pomalin is, particularly effective in increasing apple size., , ETHYLENE, l, l, , l, l, l, l, l, , l, l, l, l, l, , Ethylene is a naturally occurring volatile, hormone., Crocker (1930) reported presence of ethylene, from plant organs and named it as gaseous, hormone., Burg (1962) established that ethylene is the only, gaseous growth regulator., Production of ethylene by various organisms can, be detected by gas chromatography., Algae do not produce ethylene., A small number of bacteria and a large number, of fungi produce ethylene., All parts of seed plants produce ethylene. The, shoot apex produces maximum amount of, ethylene., Flowers and leaves before withering produce, considerable amount of ethylene., Maximum ethylene is formed in ripening fruits and, senescing tissues., Molecular weight of ethylene is 28.06 and freezing, point is –186°C., Biosynthesis of ethylene occurs from methionine, which is a sulphur containing amino acid., Inhibitors of ethylene synthesis are – amino, ethoxyvinylglycine and aminooxyacetic acid.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 467, , ▓坌ŐĺŐŕŇŐňĚř–, l, , l, , An increased concentration of CO2 inhibits many, effects of ethylene. Besides CO2, a more effective, inhibitor of ethylene action is silver ion (Ag+)., Bioassays for ethylene are triple pea test and pea, stem swelling test., , l, l, , ABSCISIC ACID, , Physiological effects of ethylene, l, l, l, l, , l, l, l, , l, l, , l, l, , l, , l, , l, l, l, , l, , Ethylene enhances abscission and senescence., Ethylene induces cellulase activity leading to, promotion of leaf abscission., Ethylene induces femaleness in monoecious, flowers as in cucurbits like cucumber, Cannabis etc., Ethylene inhibits phenomenon of geotropism, (graviperception), growth of lateral buds and, expansion of leaves., In low concentration ethylene induces root, initiation., Ethylene breaks bud and seed dormancy in some, species., Ethylene promotes elongation of stem and petiole, in submerged and partially submerged aquatic, plants, eg., Ranunculus., Ethylene enhances activity of chlorophyllase, which causes degreening phenomenon., Maximum rate of ethylene production occurs, during the period of maximum respiration just, before senescence in many fleshy fruits. This is, climacteric rise and it acts as trigger for the, conversion of unripe fruits to ripened fruits., Term climacteric was given byKidd and Went (1930)., Examples of climacteric fruits are – apple, banana,, mango, pear, peach, plum, tomato and, nonclimacteric fruits are – citrus, grape, pineapple,, strawberry, watermelon, cherry., Ethylene is a fruit ripening hormone and it, stimulates all the biochemical changes which take, place upto fruit ripening., Ethylene as ethaphone (2 chloroethyl phosphonic, acid) is used in artificial ripening and colour changes, in climacteric fruits., Ethylene induces flowering in mangoes, pineapple etc., Excess of auxin causes ethylene synthesis whereas, ethylene lowers synthesis and transport of auxin., Ethylene causes petal discolouration. Highest rate, of release of ethylene has been reported from fading, flowers of Vanda., Ethylene induces epinasty or downward bending, of leaves. In rose the effect appears even at, concentration of 1 ppm., , Ethylene inhibits root and stem elongation but, induces root hair formation., Ethylene induces seismonasty, synthesis of b1, 3, glucan., , l, , l, , l, , l, , l, l, , l, l, l, , l, , Carns and Addicott had identified abscisic acid in, 1963 while working on cotton balls and called the, compounds as abscisin I (from old cotton balls), and II (from young cotton balls)., Wareing and coworkers discovered dormin from, buds and leaves of Acer (Birch) plants which induces, dormancy in buds, underground stems etc., Abscisin I, II and dormin are all the same, compounds and term abscisic acid (ABA) was used, for these compounds., Abscisic acid is mildly 15C sesquiterpene multi role, plant hormone which act as an inhibitor because, it opposes the growth promoting effect of auxin,, gibberellins, and cytokinin thus keep their activity, under control., Abscisic acid is found in vascular plants, some, mosses, some fungi and some green algae., Site of synthesis of abscisic acid is many parts of, the plant but more inside the chloroplasts of green, cells., ABA is a naturally occurring growth inhibitor in, plants., Biosynthesis of abscisic acid takes place through, mevalonic acid or xanthophylls (violaxanthin)., Translocation of abscisic acid takes place in, xylem and phloem and also parenchyma cells, outside vascular bundles., Bioassays for abscisic acid are – rice seedling, growth inhibition test and inhibition of a amylase, synthesis in barley endosperm., , Physiological effects of abscisic acid, l, l, l, , l, l, , Abscisic acid induces dormancy in buds., Abscisic acid enhances the process of abscission, and senescence., Abscisic acid induces flowering in some short day, plants like Ribes, Fragaria etc., during long days, and inhibits flowering in long day plants., Abscisic acid stimulates the release of ethylene., Abscisic acid counteracts many effects of, gibberellins like induction of hydrolases and, aamylases in barley seedlings.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 468, , l, l, l, , l, l, l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The buds and seeds sprout only when abscisic acid, is overcomed by gibberellins., Abscisic acid (ABA) is called antigibberellin., ABA promotes ageing of leaves by stimulating, breakdown of proteins and nucleic acid through, promoting activity of their hydrolases., ABA promotes cold hardiness and inhibits growth, of pathogens., ABA has been found to induce parthenocarpic, development in rose., Use of abscisic acid promotes roots in many stem, cuttings., Excessive production of abscisic acid stops the, synthesis of RNA and proteins which causes, senescence., Abscisic acid stops mitosis in vascular cambium, towards the approach of winter., Abscisic acid is also known as stress hormone as, it is produced under conditions of stress and causes, partial closure of stomata under drought and thus, acts as antitranspirant., Leaves makes large amount of abscisic acid, during drought and it functions as messenger, that enables plant to conserve water during, drought., , Ø, , Ø, Ø, Ø, , Ø, , Ø, , Morphactins, These are a group of artificially synthesized, substances, which affect morphology and hence, called morphactins (by Schneider)., These contains ‘fluorene ring’ in their structure., Generally these are growth inhibitors., Physiological effects of morphactin are –, – Formation of cornets (fusion of leaf with stem), and ochria (fusion of calyx with other floral parts)., – Induction of gamopetalous condition., – Induction of parthenocarpy., – Root growth and shoot growth is inhibited by, morphactines, i.e., leads to shortening of plants., – Depot effect : First morphactins are, accumulated in plants and after sometime show, their effect., – Seed germination is inhibited., Wound hormone or Traumatic acid, Haberlandt (1913) reported that injured plants cells, release a chemical substance (wound hormone),, which stimulate the adjacent cells to divide rapidly, in order to heal up the wound., English et. al. (1939) finally isolated and, crystallized this wound hormone and named it as, traumatic acid.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ☻ĚőŕŐęśĘŚĽŐň–, , 469, , Chapter 49, , Human Reproduction, l, , l, , l, , l, l, l, , l, l, l, , l, l, l, l, , l, , l, , Reproduction is the process by which living, organisms produce young one of their own type, and reproductive system is a system of organs, which takes part in this process., Reproduction is an essential life process which not, only helps in survival but also helps in continuity, of that race and group immortality., Four basic processes of reproduction are – DNA, replication, cell division, formation of reproductive, units and development of new individuals., Animal reproduction is of two types – asexual and, sexual., Rate of reproduction is faster in asexual, reproduction., In asexual reproduction progeny arise from the, single existing organism without involving the, formation and fusion of gametes., Asexual reproduction involves only mitotic, divisions., It is absent in higher metazoans., Asexual reproduction is found in lower organisms, like protistan protozoans (Amoeba, Paramecium),, sponges (Scypha), coelenterate (Hydra), certain, flat worms (Planaria), some worms and tunicates, (Salpa)., Asexual reproduction is of four types fission,, budding, fragmentation and cyst & spores., In fission, body of an individual undergoes division, to produce 2 or more equal sized daughters., Fission is of two types – binary fission and, multiple fission., Binary fission involves the division of the nucleus, followed by that of the cytoplasm, breaking the, body into two young ones., Binary fission may be irregular (Amoeba),, longitudinal (Euglena), transverse (Paramecium, and Planaria) and oblique (dinoflagellates)., In multiple fission the nucleus divides into several, , l, l, l, , l, , l, , l, , l, , l, l, , l, , l, l, l, , daughter nuclei, followed by the simultaneous, division of cytoplasm., Multiple fission is found in algae among plants,, Plasmodium (malarial parasite) and Amoeba., Budding is an unequal division of the parent where, the identity of the parent body is still maintained., Budding is in contrast to binary fission where, parent body divides equally into two and no identity, of the parent is left., Budding is the formation of multicellular or, unicellular outgrowth (called bud) on or inside the, parental body., Bud formed inside the body is called gemmules or, statoblasts and formed on external surface is called, exogenous bud (eg. Hydra)., Budding is found in sponges (Scypha), coelenterate, (Hydra), annelids (Syllis) and tunicates (Salpa), among animals and among fungi it is formed in, Yeast., In fragmentation the body may break into two or, more fragments, and each fragment develops into, a complete individual, eg. Spirogyra., It is found in some flat worms (Microstomum), sea, anemones among coelenterate and echinoderms., Cysts and spores are minute propagules which, function as dissemules as well as penetrating, structures., In sporulation which occurs in many protozoa, and bacteria the asexual reproduction occurs by, the division of nucleus into several daughter nuclei, and then each daughter nucleus gets enclosed by, small amount of cytoplasm to form a spore., Asexual reproductive propagule is called blastos., An individual produced through asexual, reproduction is ramet., Clone is a group of all genetically similar, individuals which are formed through asexual, reproduction.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 470, , l, l, , l, l, , l, , l, l, l, l, l, l, , l, , l, l, l, l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Asexual reproduction involves only one parent, hence called uniparental reproduction., Parthenogenesis is the development of an, unfertilized ovum into a new individual genetically, identical with the parent. Such developments is, fairly common among insects and in many cases, may be induced artificially by various chemical or, physical stimuli., Parthenogenesis is a modified form of sexual, reproduction., In incomplete parthenogenesis there is no, biparental sexual reproduction. There are no, males and therefore such individuals are represented, by females only, eg. rotifers and certain wasps., On the basis of sex of the offspring,, parthenogenesis may be arrhenotoky, thelotoky,, amphitoky., In arrhenotoky, only males are parthenogenetically, produced, e.g. arachnids., In thelotoky, only females are parthenogenetically, produced, e.g. gall fly., In amphitoky, parthenogenetic eggs may develop, into any sex, e.g. aphids., Mictic females produce haploid eggs which can, be fertilized by males., Amictic females produce diploid eggs which, developed parthenogenetically., Sexual reproduction is a mode of multiplication, in which new individuals are formed through the, process of formation and fusion of gametes., Sexual reproduction involves meiosis during, gametogenesis and mitotic division during, development of zygote., Rate of reproduction is slower in sexual, reproduction., Sexual reproduction generally involves 2 parents, (male and female), so called biparental reproduction., It is found in higher plants and animals., Syngamy and conjugation are two types of sexual, reproduction., Syngamy involves the formation and complete, fusion of gametes to form zygote (diploid)., Endogamy (also known as self fertilization), involves the fusion of male and female gametes of, same parent (Taenia)., Exogamy (also known as cross fertilization), involves the fusion of male and female gametes, from different parents (rabbit)., , l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, , Autogamy is a type of reproduction in which the, fusing nuclei/gametes are derived from the same, cells., Conjugation correspond to cross fertilization of, higher animals. It involves temporary union of two, parents of same species which exchange their male, pronuclei to form synkaryon and then separate to, produce daughter individuals. Eg. Paramecium., Hologamy/macrogamy is a type of reproduction, in which the fusing gametes are similar to somatic, cells/individuals, eg. helizoan, Actinophrys., Microgamy/merogamy is syngamy in certain, protistans where the fusing gametes are much, smaller than the normal., Isogamy involves the fusion between, morphologically and physiologically similar, gametes., When 2 fusing gametes are morphologically or, physiologically different from each other then they, are called anisogamy or heterogamy, e.g., microgamete and macrogamete., The gametes are of two types : one is smaller and, motile called sperm, another is large, food laden, and nonmotile called ovum., Development of an organism from zygote through, embryo formation is embryogenesis., Mammalian reproductive system consists of, (i) Primary sex organs (also called gonads) viz., testes and ovaries which produce gametes, (ii) Secondary sex organs, such as prostate and, seminal vesicles in male, and uterus and, fallopian tubes in female; and, (iii) Accessory or external sex characters,, which distinguish the two sexes of a species, in appearance., Gonads are derived from mesoderm., The onset of reproductive life is called puberty., It is the time when the gonads develop both, endocrine and gametogenic function., , MALE REPRODUCTIVE SYSTEM, l, , l, , Male reproductive system consists of a pair of, testes, a paired duct system consisting of, epididymis, vasa efferentia, vas deferens,, ejaculatory duct and urethra., Secondary sex organs of males are seminal, vesicles, Cowper’s glands, prostate gland and, penis.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ☻ĚőŕŐęśĘŚĽŐň–, l, , l, l, , l, l, , l, l, , l, , l, l, , l, , Male reproductive system performs two major, functions: (i) spermatogenesis (formation of, spermatozoa), and (ii) transfer of sperm to the, reproductive tract of the female., The testis consists of two flat, oval bodies, one on, each side, remaining inside the scrotum., Scrotum is the sac of skin, situated outside the, body cavity and allows sperms to develop at the, optimum temperature, which is slightly lower than, body temperature., Removal of testes is called orchidectomy., The testis is attached to the scrotum by a band of, connective tissue known as gubernaculum testis, and the scrotum communicates with the abdominal, cavity through inguinal canal., Spermatic cord (elastic cord) connects testes with, abdominal cavity., In early foetal life, testis remain within the, abdomen. During the third week of gestation, the, testes move caudally from their position high in, the abdomen, then gradually migrate and descend, in the scrotum by the time the child is born., The temperature of scrotum is 2°C below the, body temperature, which is essential for the, formation of sperms in the testes., Failure of testis to descend in scrotum from, abdominal cavity is called cryptorchidism., Cryptorchidism produces sterility as, spermatogenesis does not occur at the higher, temperature of the abdominal cavity., The testis is covered by a tough, compact fibrous, capsule called tunica albuginea, which is externally, covered by peritoneal layer of flat cells called tunica, vaginalis which is supplied by a network of blood, capillaries called tunica vasculosa., Ø, , Ø, , Ø, , Variations in Position of Testes, In some mammals (lion, bull, horse), the testes, remain permanantly in the scrotum and keep, functioning throughout the year as in man., In certain seasonally breeding mammals, such, as bat, otter and llama, the testes enlarge,, become functional, and descend into the, scrotum in the breeding season, but thereafter, ascend into the abdominal cavity, and become, reduced and inactive., In a few cases (elephant, whale, seal) the, testes remain permanently in the abdomen., , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, l, , l, , l, l, l, , 471, , The lobules present in the gland are filled up with, convoluted seminiferous tubules, each about, 500 mm long., Several seminiferous tubules unite to form a, straight tubule which again unite forming the rete, testis., Rete testis join up to form the vasa efferentia as, a fine ciliated ductules which finally combine to, form the duct of epididymis (caput epididymis)., Each seminiferous tubule is lined by a germinal, epithelium which is formed of 2 types of cells , germ cells and sertoli cells., Germ cells undergoes spermatogenesis to form, spermatozoa., Sertoli cell (also called subtentacular cells), the, functional component of seminiferous tubule, functions as nurse cells for differentiating, spermatozoa., Sertoli cell produce androgen binding protein, (ABP), inhibin (which inhibit FSH secretion) and, mullerian inhibiting substances., Inside the stroma and between the seminiferous, tubules, groups of polyhedral cells are found which, are called interstitial cells of Leydig., Interstitial cells of leydig are abundant in early, foetal life, then gradually diminish during, childhood, increase again at puberty and, diminish in old age., Leydig cells comprise less than 10% of the, testicular volume and secrete about 78 mg of, testosterone (male sex hormone) per day., Epididymis is divided into three parts anterior, caput epididymis, middle corpus epididymis and, posterior cauda epididymis., Testis and epididymis together are called testicle., Epididymis is involved in storage (temporary),, nutrition and physiological maturation and, motility of sperms., Spermatozoa are concentrated and stored in the, lower of the epididymis (cauda) untill, ejaculation., Ejaculation is the discharge of semen due to, powerful rhythmic contractions of urethra., Prostate, Cowper’s and seminal vesicle secretes, fluids which mix with sperms to form semen., Semen, containing sperms, is a milky viscous and, alkaline fluid ejaculated by male reproductive, system during orgasm.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 472, , l, , l, l, , l, l, , l, l, l, , l, , l, , l, , l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Semen provides a fluid medium for the, transmission of sperms into the vagina, nourishes, and activates the sperm and its alkalinity, neutralize the acidity of the urethra and protects, the sperms from the acidity of the vagina., The duct system conduct the semen to the exterior., Vas deference is large duct which arises from, cauda epididymis and reach up to seminal vesicles., , l, l, l, , Glans penis is the tip of penis, which is highly, sensitive to stimulation., Prepuce is a loose, retractile foreskin which covers, glans penis., Inside the prepuce, there are modified oil glands, called glands of Tyson., , FEMALE REPRODUCTIVE SYSTEM, , In frog the vas deference is absent and the sperms, pass through Bidder’s canal, a collecting duct, in kidney., , l, , Vasectomy is the cutting of vas deferens and tying,, its two ends separately (bilateral ligation)., Ejaculatory ducts are short, straight muscular tubes, each formed by union of vas deferens and duct of, seminal vesicle. They have contractile mechanism, that aids in the emission of seminal fluid., Urethra leads from the urinary bladder through, the prostate glands & into the penis., Urethra consists of 4 parts urinary, prostatic,, membraneous & penile., Membraneous and penile form of urethra forms, the outflow pathway for the urine & for the, seminal fluid., Seminal vesicles, also called uterus masculina, is, a elongated musculoglandular sac like structure, between the urinary bladder and rectum., Secretion of seminal vesicle, formed of citric acid,, prostaglandins, stimulates vaginal contraction, to help in fusion of gametes and also contain, fructose which acts as a source of energy for, stored sperms., Cowper’s glands, also called bulbourethral, gland, is a pair of pea sized gland that lie beneath, the prostate gland and whose secretion neutralize, the acidity of urine in urethra., Perineal gland, present near the Cowper’s gland, and rectum, produce pheromones., Prostate gland is a large pyramidal gland which, lies at the base of the bladder & surrounds the first, part of the urethra. It provide milky alkaline fluid, for the nutrition of sperms in seminal vesicle., Corpora amylacea is a small acidophilic, concreations present in the lumen of prostate gland., Penis, male copulatory organ is supported by 3, tissues 2 posterior fibrous ligamentous corpora, cavernosa and one anterior highly vascular and, spongy corpus spongiosum., , l, , l, , l, , l, l, , l, l, , l, , l, l, l, l, , l, , l, , The purpose of the female reproductive system, is the continuation of the human species by the, production of offsprings., The female reproductive system includes the, ovaries, fallopian tubes, uterus, vagina,, accessory glands and external genital organs., Ovaries, the primary sex organ in human female, are responsible for producing female sex hormone, (estrogen, progesterone etc.) and gamete (ova)., The ovaries are attached to the abdominal wall by, an ovarian ligament called mesovarium (or fold of, peritoneum)., The region of attachment is known as hilus., Ovary is covered by a layer of cubical epithelium, called the germinal epithelium which is further, covered by visceral peritoneum., Beneath this epithelium, a layer of connective tissue, called tunica albuginea is present., The outer region of the ovary is composed of, developing follicles and the middle is composed, of stroma, which contains connective tissue, blood, vessels and mature follicles., The stroma consists of dense outer layer called, the cortex and a less dense inner portion called, the medulla., Scattered throughout the cortex are many ovarian, follicles of different developmental stages., The medulla is a loose connective tissue with abundant, blood vessels, lymphatic vessels and nerve fibres., Follicles are specialized structure in which oocyte, (a female germ cell) growth and meiosis I occur., These follicles are initially formed during, embryonic development by proliferation of, primordial germ cells of germinal epithelium but, start maturing (once a month) after puberty only., The follicles continues to grow under the influence, of follicle stimulating hormone (FSH) and the, follicular cell proliferate to form several layers of, granulosa cells around the primary oocyte., Contained within each primary ovarian follicle is, an oocyte, the potential ovum or egg cell.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ☻ĚőŕŐęśĘŚĽŐň–, l, , l, , l, , l, , l, l, , l, , l, , l, , l, l, , l, l, l, , l, l, , At birth, a female’s ovaries contain some 2 million, follicles, each with an ovum that has begun meiosis, but which is arrested in prophase of the first, meiotic division. At this stage, the ova are called, primary oocytes., Primordial follicles which consist of a primary, oocyte surrounded by a single layer of flattened, cells, develop in the foetus and are the stages that, is present in the ovaries at birth and throughout, childhood., Mature follicles are known as Graafian follicle, which occupy a single cavity called antrum and, contains a secondary oocyte ready for ovulation., Mature follicle has 3 distinct layers outer theca, externa (fibrous), middle theca interna (cellular), and inner membrana granulosa., Theca interna and theca externa are derived from, cortex., The cells of theca interna of the follicle are the, primary source of circulating estrogen under the, influence of LH., Theca interna cells have many LH receptors. LH, acts on theca interna via cAMP to increase, conversion of cholesterol to androstenedione., Some of the androstenedione is converted to, estradiol which enters the circulation., Ruptured Graafian follicle is called corpus, luteum, a yellow endocrine gland, which secretes, progesterone hormone., Corpus luteum loses its yellow colour and become, inactive and transformed into a small cell mass, called corpus albicans., A female child at birth possess 80,0000 follicles in, her ovaries, but about 400 mature and discharge, their ova, the rest undergo degeneration., Degenerated follicles are also called atretic follicle., The mass of granulosa cells enclosing the mature, ovum projects into the antrum, forming a hillock,, the cumulus oophorous or discus proligerous., The ovum is surrounded by the prominent, glycoprotein layer, zona pellucida., Zona pellucida develops as a jelly coat around the, primary oocyte & is surrounded by the granulosa cells., The corona radiata is a well defined, radially, arranged layer of columnar cells immediately, surrounding the zona pellucida., Cytoplasm of the ovum is called ooplasm., Yolk is absent in the ovum, thus human eggs are, alecithal., , l, l, l, l, , l, l, , l, l, , l, l, , l, l, , l, l, , l, , l, l, l, l, l, , 473, , Oviducts or fallopian tubes are about 12cm long, and carry eggs from the ovaries to the uterus., Each oviduct is differentiated into four parts , infundibulum, ampulla, isthmus & uterine part., Fimbriae are situated in a dilated funnel shaped, free end of fallopian tube called infundibulum., Fimbriae, found on the lateral end of each tube, are, fringe like protrusions that generate currents in, the fluid surrounding the ovary and pull the, ovum into the fallopian tube., Ampulla is a part behind infundibulum where, fertilization of ovum takes place., Cilia lining the oviduct beat and smooth muscle, contracts causing peristaltic movements which, move the egg down the oviduct to the uterus., Tubectomy is the cutting of oviduct and tying its, two ends separately (tubal ligation)., The uterus in human is about 7.5 cm long and, 5 cm wide and is about the size and shape of an, inverted pear., Uterus lies behind the urinary bladder., Uterus is the site for implantation of the pre, embryo and for the subsequent embryonic and foetal, development., The cervix is the narrow, lower end of the uterus, that opens into the vagina., Uterus walls is composed of three layers outer, perimetrium, middle myometrium and inner, endometrium., The surgical removal of uterus is called, hysterectomy., The myometrium is thickest layer and contains, areolar connective tissue and smooth muscle, fibres., During pregnancy the cells of the myometrium, increases in size to accomodate the growing foetus, and contracts during labor and delivery at the end, of gestation., The endometrium is composed of two layers –, basilar and functional., Basilar layer is permanent, vascular and very thin., The functional layer of endometrium is regenerated, and lost during each menstrual cycle., During pregnancy the endometrium forms the, maternal section of the placenta., Estrogen and progesterone from the ovaries, stimulates the growth of blood vessels to thicken, the functional layer in preparation for a possible, embryo.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 474, , ŕďőĽę– ĐĽŐńŐĹť, , Mammals other than primates (e.g., hamster, rabbit), have more complex female reproductive tracts,, where part of the uterus divides to form uterine, “horns” each of which leads to an oviduct., l, l, l, , l, l, , l, l, , l, l, , l, , l, l, , l, l, l, l, , Vagina is a muscular tube about 8 10 cm long, whose walls contain elastic tissue., Vagina is located posterior to the urethra and, anterior to the rectum., The vagina receives sperm from the male’s penis, during sexual intercourse, serves as the exit for, blood during menstrual flow and serves as the, birth canal during child birth., The opening of the vagina in young females is, partially closed by a thin membrane called hymen., During reproductive life the vagina contains, Lactobacillus acidophilus which keeps the vaginal, pH between 4.9 – 3.5 by producing lactic acid, from glycogen. This acidity helps to prevent, vaginal infections., The space between vaginal wall and the cervix is, called fornix., The external female genitalia, also called the vulva, are the accessory structure of the female, reproductive system that are external to the vagina., The vulva includes the clitoris, labia majora, labia, minora and Bartholin’s gland., Clitoris (present in front of urethral opening) in, female and penis in male are said to be homologous, structure due to their same embryonic origin (they, differ only by the presence or absence of testosterone)., Clitoris, contains erectile tissue and many nerve, endings in a sensitive glans within a prepuce which, totally encloses the glans. This is the most sensitive, point for female sexual stimulation., Clitoris is very sensitive as it contains numerous, sensory structures (e.g., Meissener’s corpuscles)., The sides of the vulva have two small fleshy folds,, the labia minora (lesser lips) which are hidden by, larger hairy folds the labia majora (greater lips)., Labia majora are homologous to scrotal sacs of, a male., Paired Bartholin’s glands are situated on each side, of the vaginal opening., Bartholin’s glands correspond to the Cowper’s, gland of male., Secretion of Bartholin’s gland help in lubrication, during copulation and counteracting urinary, acidity., , l, l, , l, l, , l, , l, , l, l, , l, , l, l, , Mammary glands are compound saccular, modified sweat glands., Mammary gland, which are located in the breast, overlying the pectoralis major muscles are present, in both sexes but usually functional only in, females., Gynaecomastia is the overgrowth of breast in male., It is a one symptom of Klinefelter’s syndrome., Externally, each breast has a raised nipple, which, is surrounded by a circular pigmented area called, the areola., The nipples are sensitive to touch, due to the fact, that they contain smooth muscle that contracts and, causes them to become erect in response to, stimulation., Internally, the adult female breast contains 15 to 20, lobes of glandular tissue that radiate around the, nipple., A lactiferous duct collects the milk from the lobules, within each lobe and carries it to the nipple., Just before the nipple the lactiferous duct enlarges, to form a lactiferous sinus (ampulla), which serves, as a reservoir for milk., Mammary gland function is regulated by, hormones. At puberty, increasing levels of, estrogen stimulate the development of glandular, tissue in the female breast., Progesterone stimulate the development of the, duct system., During pregnancy these hormones (estrogen &, progesterone) enhance further development of the, mammary glands. Prolactin (from the anterior, pituitary) stimulates the production of milk within, the glandular tissue, and oxytocin (from the, posterior pituitary) causes the ejection of milk from, the glands., , Menstrual cycle, l, , l, , l, l, , The activity of the hormones of the ovaries and, anterior pituitary gland and the resultant changes, in the ovaries and uterus are known as the, menstrual cycle., Menstrual cycle is a period of cyclic changes that, occur in the reproductive tract of human females, and other primates with a periodicity of 28 days., Menstrual cycle is controlled by FSH, LH, estrogen, and progesterone., A woman’s reproductive cycles last from menarch, to menopause.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ☻ĚőŕŐęśĘŚĽŐň–, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, l, l, l, l, , l, l, , 1st menses is called menarche while the onset of, menses and development of secondary sexual, character is called puberty, usually at age of 13., If puberty starts early then it is known as precocious, puberty. Earliest known puberty was found in a 6, year old child., Menopause (climacteric) is stopping of ovulation, and menses. Its average age is 51 years. Post, menopausal effects include hot flashes, irritability,, fatigue, anxiety, decreased strength of bones, etc., Menopause is marked by decreased levels of, ovarian hormones and increased levels of, pituitary follicle stimulating hormone (FSH) and, luteinizing hormone (LH)., Menstrual cycle consists of menstrual phase,, proliferative phase (follicular phase) and, seccretory phase (luteal phase)., Days 15 of the cycle are known as the menstrual, phase., During menstrual phase, menstruation occurs. At, the beginning of this stage, blood levels of, progesterone and estrogen have dropped dramatically, because of the degeneration of the last cycle’s corpus, luteum. This triggers the shedding of all but the, deepest layer of the endometrium., The detached portion of the endometrium as well, as blood will pass through the vagina as the, menstrual flow (menses)., Menstruation, is often described as the funeral of, the unfertilized ovum or as the weeping of the, uterus for the lost ovum., During this phase, FSH levels are rising and as a, result, follicular development has begun to proceed, and follicle secretion of estrogen has begun., Day 514 are known as the proliferative phase., Proliferative phase consists of growth of, endometrium of uterus, fallopian tube and vagina., In ovary, a Graafian follicle grows, matures and, secretes estrogen during this phase., Estrogen is the hormone active during, proliferative phase., As follicular development proceeds, blood estrogen, levels rise. This estrogen causes the regeneration, of the stratum functionalis. The endometrium grows, thicker and becomes more vascularized and, glandular. At this time, cervical mucus begins to, get less viscous., The follicular phase ends with ovulation., Ovulation, prompted by luteinizing hormone from, , l, , l, , l, , l, l, , l, , l, l, l, l, l, l, l, , l, , l, , l, , 475, , the anterior pituitary, occurs when the mature follicle, at the surface of the ovary ruptures and releases the, secondary oocyte into the peritoneal cavity., The follicle that ruptures at the time of ovulation, promptly fills with blood forming corpus, haemorrhagicum, which will eventually be absorbed., Ovulation occurs at the end of the proliferative, phase i.e., 14th day or midday during menstrual cycle, and coincides with the beginning of the next phase., After ovulation and in response to luteinizing, hormone, the portion of the Graafian follicle that, remains in the ovary enlarges and is transformed, into a corpus luteum containing yellow substance, (called lutein) and the luteal phase begins., The corpus luteum is a glandular structure that, secretes progesterone and some estrogens., If fertilization does not take place, the corpus, luteum remains functional for about 10 days then, it begins to degenerate into a corpus albicans by, losing its yellow colour, which is primarily scar, tissue, and its hormone output ceases., It fertilization occurs, the corpus luteum persists, and continues its hormone functions until the, placenta develops sufficiently to secrete the, necessary hormones., The fall in FSH level and arise in LH causes, ovulation., Increased level of estrogen in blood stimulates, the pituitary to secrete another hormone LH., If the ovum is not fertilized, the higher level of, progesterone inhibits the production of LH., The withdrawal of LH causes regression of corpus, luteum and a fall in progesterone level., The ovum lives for approximately 72 hrs, after, it has extruded from the follicle., Human ovum loses its ability to be fertilized about, 24 hrs after ovulation., The subsequent 14 days (i.e., 15 to 28) in which, corpus luteum is active is referred to as the, secretory phase., During secretory phase, the endometrium prepares, for the implantation of an embryo and the corpus, luteum is active and secretes progesterone., The progesterone acts to thicken the uterus even, more and become even more vascular and glandular., The endometrium also begins to secrete nutrients, into the uterine cavity, so as to support an embryo, prior to implantation., The rising progesterone also causes cervical mucus
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 476, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , to become viscous again (forming the cervical plug),, which helps prevent bacteria or any more sperm, from entering the uterus., As progesterone levels rise, they inhibit the release, of LH. Without LH, the corpus luteum begins a, steady decline., At the end of secretory phase, corpus luteum, degenerates in the ovary, progesterone secretion, fails, the overgrown uterine endometrium breaks, down and menstruation takes place., As the progesterone declines, the endometrium begins, to synthesize vasoconstrictive chemicals. The spiral, arteries become constricted and the outer endometrial, cells are devoid of oxygen. More and more endometrial, cells begin to die and eventually the endometrial, capillaries will rupture and blood and dead cells will, begin to slough off through the vagina. This is, menstruation and the cycle then repeats., Menstruation is absent during pregnancy, may, be suppressed during lactation and permanently, stops at menopause., , l, , Menstruation blood is predominantly arterial,, with only 25% of the blood being of venous origin., It contains tissue debris, prostaglandins, and, relatively large amounts of fibrinolysin from, endometrial tissue., , Estrous cycle, , Mammals, other than primates do not menstruate,, and their sexual cycle is called an estrous cycle., There are four phases of estrous cycle., (a) Anestrous or Diestrous This is the resting, period when there is no sexual activity., (a) Proestrous This is preparatory phase during, which the ovarian follicle is developing under, the influence of FSH., (c) Estrous The period of heat or estrous, coincides with the greatest development of, the Graafian follicles., (d) Metestrous After estrous, there is a, degenerative metestrous but this is generally, merged into the state of pregnancy., , Sexual reproduction, , includes, , includes, , Male reproductive organ, , Female reproductive organ, , consists of, Seminal, vesicle, , Cowper's, gland, , Prostate, gland, , Consists of, , Testis, , Penis, , introduces, sperm into, , Vagina, , produces, , Ovaries, produces, , secretes, , is, fertilized, at, Ovum, , Sperm, , Seminal fluid, , Oviducts, , form, , Uterus, forms, part, of, Placenta, , fertilize together, to form, , Semen, , implants at, Zygote, , forms, part, of, , divides to form, Embryo, , DISORDERS OF REPRODUCTIVE, SYSTEM, l, , Prostatitis is an inflammation of the prostate gland., When the prostate gland swells, it frequently blocks, , l, , the urethra and makes urination painful or difficult., Untreated prostatitis can lead to kidney damage., After an age of sixty the prostate gland often, becomes enlarged leading to hypertrophy., Prostate cancer is an extremely common
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ☻ĚőŕŐęśĘŚĽŐň, , l, , l, , l, , l, , malignancy. Malignant prostate cells are usually, stimulated by testosterone, so treatment often, involves removal of the testes, thereby preventing, production of the hormone., Sterility, in males is the inability of sperm to fertilize, an ovum. In females it is the inability to conceive, due to the inadequacy in structure or function of, the genital organs., Disorders of ovulation, –, Oligomenorrhoea is a erratic periods or short, (oligo) menses., –, Amenorrhoea is the absence of menstruation., It may be physiological (i.e. prior to puberty, or due to pregnancy, lactation, or the, menopause), or secondary due to a, gynaecological disorder or systemic disease., –, Primary amenorrhoea is the failure to, establish menstruation. The most common, cause of primary amenorrhoea associated with, normal secondary sexual characteristics is an, anatomical abnormality of the genital tract,, e.g. absent vagina and uterus.Common causes, of primary amenorrhoea with associated, delayed puberty are Turner’s syndrome, gonadotrophin deficiency and constitutional, delay., –, Secondary amenorrhoea is defined as the, absence of menstruation for 6 consecutive, months in a woman who has previously had, regular periods.The commonest cause is, pregnancy and polycystic ovary syndrome;, hyperprolactinaemia; premature ovarian, failure and weightrelated amenorrhoea are, other common causes., –, Dysmenorrhoea is painful menses., Polycystic ovary disease is a condition where there, are multiple tiny cysts in the ovaries. The LH level, is characteristically high with normal FSH. and, estrogen levels.There is often oligomenorrhoea or, amenorrhoea and also characterised by hirsutism,, acne, infertility etc., Hyperprolactinaemia : The level of the hormone, prolactin is very high while the levels of F.S.H. and, estrogen are lowered. This condition is known as, hyperprolactinaemia. There is either oligomenorrhoea, or amenorrhoea. Discharge from the nipples is also, , l, , l, , l, , l, , 477, , a symptom of this condition as this is the hormone, responsible for milk production., Ovarian cysts are fluid filled tumor of the ovary., Such cysts sometimes rupture and regress (get, smaller) during pregnancy, but in older women they, sometimes must be removed surgically. Some grows, to very large sizes and have to be removed., Impotence or erectile dysfunction (ED) is the, inability of the male to produce an adequate erection, for satisfactory sexual intercourse. Damage to nerves,, arteries, smooth muscles, and fibrous tissues, often as, a result of disease, is the most common cause of ED., Pelvic inflammatory disease (PID) is a long lasting, (chronic) infection affecting the womb (uterus), the, tubes which deliver eggs to the womb (fallopian tubes), and the nearby structures in the lower abdomen. Pelvic, inflammatory disease is most likely to occur between, the ages of 15 and 25, in sexually active women. PID, occurs when disease causing organisms migrate, upward from the urethra and cervix into the upper, genital tract. The major symptoms of PID are lower, abdominal pain and abnormal vaginal discharge.Other, symptoms such as fever, pain in the right upper, abdomen, painful intercourse, and irregular menstrual, bleeding can occur as well., Sexually transmitted diseases or venereal diseases, (V.D.) are spread primarily through sexual contact., These are –, –, Gonorrhoea. It is caused by a bacterium,, Neisseria gonorrhoeae., –, Syphilis. Syphilis is caused by the spirochaete, (spiral bacterium) Treponema pallidum., –, Genital herpes. Genital herpes is caused by, a virus, herpes virus hominis, type 2., –, AIDS (Acquired Immune Deficiency, Syndrome). This disease which results in a, breakdown of a person’s immune system, may, be caused by a viral infection. AIDS is caused, by the human immunodeficiency virus (HIV)., AIDS, a commonly fatal disease, has been on, the increase in the world. High risk groups, include gay (homosexual) men, heroin addicts, and haemophiliacs. The disease may be, transmitted via blood transfusion, the use of, dirty hypodermic needles and through sexual, contact.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 478, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 50, , Embryonic Development, l, , l, , Embryology deals with the developmental changes, that a zygote undergoes till the formation of an, adult form., Gametogenesis, fertilization, cleavage,, blastulation, gastrulation and organogenesis are, the phases of embryonic development., , l, l, , l, , GAMETOGENESIS, l, , l, , Gametogenesis is the process of gamete (sperm or, egg) formation which includes spermatogenesis and, oogenesis., Gametogenesis is divided into the following phases –, extragonal origin of primordial germ cells;, proliferation of germ cells by mitosis and meiosis;, structural and functional maturation of ova and, spermatozoa., , Spermatogenesis, l, , l, l, l, l, , l, , l, l, , Spermatogenesis, is the process of producing, sperms with half the number of chromosomes, (haploid) as somatic cells., Spermatogenesis is a continuous process., Spermatogenesis occurs in seminiferous tubules at, the time of puberty and continues throughout life., Cells involved in spermatogenesis are – sertoli cells, (nurse cells) and Leydig cells., Sertoli cells provide support and environment, for germ cells to develop and mature in, association with producing hormones estrogen, and inhibin (which suppresses pituitary FSH)., From outside inwards the following five layers are, found in seminiferous tubule the spermatogonia,, primary spermatocytes, secondary sperm, atocytes, spermatids and spermatozoa., During spermatogenesis one spermatogonium, produces 4 sperms., Spermatogenesis completes through the following, phases – multiplicative phase, growth phase,, maturation phase and spermiogenesis., , l, , l, l, , l, , l, , l, , l, l, l, l, l, , In multiplicative phase the sperm mother cells, divide by mitosis and produce spermatogonia., The spermatogonia grow in size to form large, primary spermatocytes by getting nourishment, from sertoli cells in growth phase., Maturation phase involves meiosis I in which, primary spermatocytes divide to produce secondary, spermatocytes and meiosis II which produce, spermatids. Thus each primary spermatocyte gives, rise to four haploid spermatids., Spermiogenesis or spermateleosis is process of, formation of flagellated spermatozoa from, spermatids., Spermiogenesis begins in the seminiferous tubule, but usually completed in epididymis., The process by which spermatozoa are shed into, the lumen of seminiferous tubule for transport are, called spermiation., The main structural divisions of a typical sperm are –, head, neck, middle piece and tail all of which are, contained by a continuous plasma membrane., The head contains two main parts – nucleus and, the acrosome – performing two main functions, respectively – genetic and activating., Acrosome forms a cap in front of nucleus, containing lytic agent which dissolves egg, membrane during fertilization., Acrosome of mammalian sperm produces sperm, lysins called ‘hyaluronidase’., If acrosome is removed from a sperm, it will fail, to penetrate into ovum., Neck is very short containing proximal and a, distal centriole., The two centrioles of the spermatids become, arranged one after the other behind the nucleus., The anterior one is known as the proximal, centriole.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŇĐŕťŐňĽĘ– ▼ĚŢĚńŐőŇĚňŚ, , Ø, , Ø, , Ø, , l, , l, l, l, , l, , l, , l, , l, , Acrosome contents and their functions, Hyaluronidase It is a hydrolytic enzymes., It lyses the glycosaminoglycans in the, extracellular matrix holding the cells of the, corona radiata together. As the coronal cells, become more loosely associated, sperm cells, can propel themselves inward, toward the, zona pellucida by making a receptive cone or, fertilization cone through the cytoplasm of, the egg., • Hyaluronidase may also be involved in, breaking down the zona pellucida., • It is used in medicine to increase the, absorption and diffusion of drugs, administered by injection or application., Neuraminidase – It is also a hydrolytic, enzyme, removes neuraminic acid (sialic acid), from glycoproteins. In experimental studies,, a neuraminidasetreated zona pellucida cannot, be penetrated by sperm cells. Thus the, acrosomal neuraminidase may aid in, preventing more than one sperm from entering, on ovum (polyspermy)., Zona lysins – These are proteolytic enzymes, that are capable of degrading the zona, pellucida, perhaps easing the passage of sperm, cells to the ovum., , The proximal centriole is usually located on the, neck of spermatozoa. During fertilization, it is, introduced to egg., The proximal centriole is required for the first, cleavage., The posterior centriole is known as the distal, centriole. It changes into basal bodies., Distal centriole gives rise to the axial filament (of, the sperm) which passes through the middle piece, and extends into the tail., Middle piece contains spiral rows of, mitochondria which provide energy and strength, to the sperm for locomotion., Tail or flagellum is a fine vibrating posterior, portion of sperm which helps in swimming. Tail, is made up of axial filament and small amount, of cytoplasm., In man, the sperm released from the testis takes, this route to reach the ureter vasa efferentia,, epididymis, vas deferens and urethra., The human sperm was first seen by Hamm and, Leeuwenhoek., , l, l, , l, l, , 479, , Hormones that affect spermatogenesis are, testosterone, estradiol, inhibin, FSH, LH and GnRH., Sperm take 74 days to form and a further 26 days, to mature and pass through the epididymis and, vas deferens before ejaculation., Human sperms move at a speed of about, 3 mm/min through female genital tract., Temperature is very crucial factor for the, development of sperms. For any reason if the testes, fails to descend from the abdominal cavity, spermatogenesis does not takes place and leads to, sterility., , Oogenesis, l, l, , l, , l, l, , l, , l, , l, , l, , l, l, l, , Oogenesis is the discontinuous process involved, in the development of mature ovum in ovary., Oogenesis begins before birth, stops in midprocess, and only resumes year after menarch (the first, menstrual bleeding)., Oogenesis occurs through the following phases –, multiplicative phase (formation of oogonia, mitotically from the primary germ cells), growth, phase (growth of oogonia into primary oocyte) and, maturation phase (formation of mature ova from, primary oocyte through meiosis)., Oogonia undergo mitosis only in embryo., Maturation phase produce two haploid cells larger, one called secondary oocyte and the smaller one, called polar bodies (1st polar body)., Meiosis II of secondary oocyte results in the, formation of functional egg or ovum and a, second polar body. The first polar body may also, divide to form two polar bodies of equal sizes which, do not take part in reproduction and ultimately, degenerates., First maturation division may be completed in, the ovaries just prior to ovulation but second one, (final) is completed outside the ovary after, fertilization., Secondary oocyte is female gamete in which the, 1st meiotic division is completed and second, meiotic division (metaphase stage) has begin., Secondary oocyte complete the second meiotic, division only after fertilization by the sperm in, fallopian tube., The egg is released at secondary oocyte stage, under the effect of LH., Oogenesis ends at menopause., Polar bodies are formed only in oogenesis at the, time of the formation of secondary oocyte.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 480, , ŕďőĽę– ĐĽŐńŐĹť–, , Isolecithal, Yolk is uniformly distributed, throughout the cytoplasm of egg, e.g.,, protochordates and echinoderms, , Alecithal, Eggs without yolk,, e.g., mammalian eggs., , Telolecithal, Yolk is concentrated towards vegetal, pole, cytoplasm and nucleus lie near, animal pole, e.g. birds and reptiles, Centrolecithal, Yolk is concentrated in the centre of, egg with cytoplasm surrounding it,, e.g. insects., Discoidal or Meiolecithal, Almost whole of the egg is occupied, by the yolk except small disc of active, ooplasm, e.g., birds and reptiles., , Eggs, On the basis of, distribution of yolk, , allows diffusion of oxygen and CO2 ,, e.g., birds, reptiles., , l, , l, , l, , l, , l, , l, , On the basis, of amount of yolk, , On the basis of presence or, absence of shell, , Cleidoic, Surrounded by water proof porous shell,, , l, , Microlecithal, Eggs with very little yolk,, e.g., sea urchin, starfish., , Vitellogenesis is the process of laying down of, yolk in the primary oocyte. It takes place in, prophase I., The mature ovum or egg or secondary oocyte is, spherical in shape, contain nucleus & the largest, cell in the body., Zona pellucida is the thick noncellular membrane, that develops around the oocyte within the ovarian, follicle. It is penetrated by atleast one spermatozoan, at fertilization and persists around the blastocyst, until it reaches the uterus., Corona radiata is a layer of follicle cells that, surrounds a freshly ovulated ovum & adhere to the, outer surface of the zona pellucida when the ovum, is set free from the follicle., The membrane forming the surface layer of, cytoplasm is called vitelline membrane., The cell substance (cytoplasm) of the ovum is called, yolk or ooplasm, the haploid nucleus is the germinal, vesicle & the nucleolus is the germinal spot., A narrow previtelline space, present in between, the zona pellucida and plasma membrane (vitelline, membrane, inner one), consists of 13 polar bodies., , l, , l, , l, , l, , Mesolecithal, Eggs containing moderate, amount of yolk,, e.g., frog, Megalecithal or, Macrolecithal, Eggs containing large, amount of yolk,, e.g. reptiles and birds., , Noncleidoic, Shell is absent,, e.g., human egg., , The side of the ovum which extrudes polar bodies, is termed as animal pole and the opposite end is, vegetal pole., Primary egg membrane is the vitelline membrane, and is produced by the egg itself. Types of primary, egg membranes are jelly envelope (echinoderm),, vitelline membrane (mollusca, amphibians &, birds), zona pellucida (mammals) and zona radiata, (shark, some amphibians & reptiles)., Secondary egg membrane is the one which is, secreted outside the primary egg membrane by a, layer of follicular cells that surrounds the oocyte., It occurs in the form of a chitinous shell, surrounding the egg in insects, ascidians and, cyclostomes and is called chorion., Tertiary egg membrane are formed by the cells of, oviducts or other accessory parts of the maternal, genital tract while the egg is passing from the ovary, to the exterior., Eg. (i) The albumen layers (hen’s egg), shell, membranes and outermost calcareous shell of, reptiles and birds., (ii) Three concentric layers of albuminous jelly, found around the egg of frog (secreted by oviducts).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŇĐŕťŐňĽĘ– ▼ĚŢĚńŐőŇĚňŚ, , FERTILIZATION, l, , l, l, , l, , l, , l, l, l, l, l, , l, , l, , l, l, l, , l, , Fertilization is the process of fusion of the, sperm with an ovum to form a diploid cell called, zygote., Fertilization activates the secondary oocyte cell, to complete the division., Fertilization normally occurs when sperm and, egg interact in the upper third of the oviduct, (ampulla)., Sperm gain entry through a speciesspecific, mechanism of contacting the vitelline membrane, then fusing with the egg plasma membrane before, the sperm nucleus enters the cell. Once the sperm, and egg nuclei fuse, fertilization is accomplished., Only single sperm penetrates into the ovum., Fertilization of egg with only one spermatozoa is, known as monospermy., Polyspermy is the entry of more than one sperm, nucleus into an ovum at fertilization., After fertilization the fertilized ovum moves down, the uterus for implantation., Fertilization may be external (outside the body) or, internal (inside the body of female)., In mammal, fertilization is internal as it take place, in fallopian tube., Fertilization involves the following steps :, approximation of sperm and ovum, acrosome, reaction, egg reaction, penetration of sperm,, activation of ovum, fusion of sperm and egg, nuclei., First step in the approximation of sperm and, ovum during process of fertilization is fertilizin, antifertilizin reaction., Fertilizin (glycoprotein or mucopoly, saccharides) is a chemical secretion produced in, egg to attract the sperms for fertilization., Acrosome reaction in sperm is triggered by release, of fertilizin., Antifertilizin, acidic protein is produced by sperm, on the surface of cytoplasm., Capaciation is the preparation of sperm to fertilize, the ovum. It is the final stage in the maturation, process of spermatozoan. It takes place inside, the genital tract as the sperm penetrates the ovum., Capaciation is associated with removal of adherent, seminal plasma proteins, reorganization of plasma, membrane lipids and proteins. It also seems to, , l, , l, , l, , l, l, , l, , l, , l, , l, l, l, , l, , l, , 481, , involve an influx of extracellular calcium, increase, in cyclic AMP, and decrease in intracellular pH., Capaciation occurs while sperm resides in the, female reproductive tract for a period of time,, as they normally do during gamete transport. Most, importantly capaciation appears to destabilize the, sperm’s membrane to prepare it for the acrosome, reaction., The sperm enters the ovum by passing through the, corona radiata, the zona pellucida and the vitelline, membrane., When the acrosome of the spermatozoa touches, the surface of egg, the cytoplasm of the egg bulges, forward forming receptive cone or fertilization, cone., The receptive cone is the region where sperms, enters the egg., Penetration of zona pellucida is probably facilitated, by release of hyaluronidase from the acrosomal, cap., After a sperm has penetrated an ovum, entry of, other sperm is prevented by development of, fertilization membrane (formed by zona pellucida), in the egg., Extrusion of second polar body from egg nucleus, occurs after entry of sperm before completion of, fertilization., Cortical reaction is a massive exocytosis of cortical, granules (containing mixture of enzymes like, proteases) to diffuse and alter the structure of zona, pellucida inducing zona reaction., Zona reaction represent the major block to, polyspermy., In human both the head and the tail of the, spermatozona enter the cytoplasm of the oocyte., The fusion of gametic pronuclei is called, karyogamy while the mixing of two sets of, chromosomes of two gametes is ca lled, amphimixis., A single ejaculation contain many billion, spermatozoa inspite of requiring one for, fertilization as very few survive the swim through, the female reproductive system to fertilize an egg., Because some dies in the acidic vaginal fluid, some, lost in the recesses of the cervical wall etc., Fertilization is important to initiate the embryonic, development of the egg and to restore the, chromosomes number of the species.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 482, , ŕďőĽę– ĐĽŐńŐĹť, , In Vitro Fertilization (IVF), In vitro fertilization is a fertility process first, succeeded in 1978 by Late British gynaecologist, Dr. Patrick Steptoe and his coresearcher,, embryologist Robert Edward., The technique of IVF involves removing eggs, from a woman, fertilized in a culture medium,, outside the female body and then transferring, the fertilized egg (now called zygote) into the, uterus through vagina between the 2 and 8 cell, stages. So the pregnancy starts in the woman, and further development of the child continues, in the womb till it is born. The whole procedure, is called as development of test tube baby., The IVF technology is a boon to childless couple., First attempt to produce a test tube baby was, made by an Italian scientist Dr. Petrucci in 1959., But this human embryo survived for only 29 days., The World’s first test tube baby (a baby girl), named as Louise Joy Brown was born on July, 25, 1978 in Great Britain. India’s first test tube, , CLEAVAGE, IMPLANTATION,, GASTRULATION, l, , l, , l, , l, , l, , l, , baby was born in Calcutta on October 3rd, 1978., Her name is Durga., , Table : Abnormal fertilizations, Polyspermy Penetration of many sperms into, an ovum simultaneously. Only one, set of the spermatozoa will be, successful in uniting with female, pronuclei., Polygyny, When two female pronuclei unite, with a male pronucleus., Polyandry, Conjugation of two or more male, pronuclei with a female, pronucleus., Gynogenesis Activation of egg by sperm, but, there is no fusion of its, pronucleus., Androgenesis Nonparticipation of female, pronucleus in fertilization., Somatic, Common in angiosperms,, fertilization characterized by involvement of, two pronuclei of male, one of, which fuses with the egg nucleus, and the other with two polar, nuclei. The second fusion forms, the triploid endosperm nucleus., , l, , l, , l, l, l, l, , l, l, , Cleavage, also called segmentation, is a rapid, mitotic division of the zygote to form multicellular, blastula., Holoblastic cleavage, when whole of the egg is, divided, is found in microlecithal and mesolecithal, egg., Holoblastic cleavage may be equal (blastomeres, are of equal size, eg. starfish, Amphioxus) and, unequal (blastomeres are of unequal size called, micromeres and macromeres, eg. amphibians and, lower fishes)., Equal holoblastic cleavage occurs in microlecithal, or isolecithal eggs and unequal holoblastic, cleavage occurs in mesolecithal or telolecithal egg., Meroblastic cleavage, when a part of egg is, divided, is found in polylecithal eggs. It may be, discoidal (e.g. birds) or superficial (e.g. insects)., On the basis of fate of blastomeres, cleavage may, be determinate or mosaic cleavage (in which, blastomere is fixed and has its characteristic position, and unalterable fate and complete embryo is formed, only when all the blastomeres are present, eg annelida,, mollusca) and indeterminate or equipotential, cleavage (in which fate of blastomere is not rigid and, have no characteristic position and alterable fate and, even an isolated group of blastomeres can form a, complete embryo, eg echinoderm and chordate)., Cleavage in fertilized egg of humans starts in, fallopian tube about 14 or 15 hours after, fertilization during its passage through the fallopian, tube to the uterus., Basically both cleavage and mitosis are identical, because these lead to the formation of two cells, with diploid number of chromosomes., Cleavage occurs more readily in the active, cytoplasm., Cleavage restores the cell size and nucleoplasmic, ratio of the species., Cleavage in human is equal holoblastic., Morula looks like a little mulberry. Morula is the, solid ball of 32 cell stage without cavity which is, formed after Vth cleavage and 31 cell division., Morula changes to blastula due to rearrangement, of blastomeres., A morula can be differentiated from blastula in, absence of cavity.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŇĐŕťŐňĽĘ– ▼ĚŢĚńŐőŇĚňŚ–, l, l, , l, , l, l, l, , l, l, , l, l, l, l, , l, l, , l, l, , l, , Blastula is typically a hollow, multicellular ball, like embryo produced at the end of cleavage., A fluid filled cavity of blastula is called, blastocoel or segmentation cavity or blastocystic, vesicle., Blastula is divided into 4 types stereoblastula, (solid blastula without blastocoel, eg. Nereis),, coeloblastula (blastula with a prominent blastocoel,, e.g. frog), discoblastula (occurs in polylecithal egg,, a blastula having many layered disc of blastomeres, above the yolk, develops as a result of meroblastic, division, eg. hen), superficial blastula (having a, single layer of blastomeres around central yolk,, blastocoel absent, eg. insects)., Blastula formation is called blastulation., Mammalian blastula with a large blastocoel is called, blastocyst (in humans)., As a blastocyst is formed, zona pellucida becomes, thinner and finally disappears. By this time the, developing embryo reaches the uterus and implants, into the uterine lining., Blastocyst has 3 parts trophoblast, inner cell, mass and blastocoel., Trophoblast is the outer cellular wall of blastocyst, that forms hCG (secretion of hCG begins the day, the trophoblast is embedded in the endometrial, lining), villi, chorion, amnion, and foetal parts, of placenta., Inner cells mass (embryoblast) forms the body of, embryo., Blastocoel is fluid filled cavity which helps in rapid, expansion of blastocyst of blastodermic vesicle., Fate mapping is done at late blastula stage to, determine the fate of cells of blastula., Implantation or nidation is the embedding of a, fertilized mammalian egg into the wall of the uterus, (womb) where it will continue its development., The site of implantation determines the position, of the placenta., Implantation (of blastocyst) occurs in the, endometrium near the fundus, generally between, 6th to 9th days after fertilization., The site of implantation determiners the position, of the placentr., Implantation begins first with attachment, (adplantation) of the blastocyst through the outer, trophoblast cells of the uterine lining., Implantation outside the womb (like ovary,, , l, , l, l, , l, l, , l, , l, , l, l, , l, , l, , l, , l, , l, , 483, , abdomen etc.) and too low down within the uterus, results is abnormalities like ectopic pregnancy and, placenta praevia respectively., In humans implantation is of interstitial type in, which the embryo is buried in the uterine epithelium, which completely surrounds it., The embryo in human female gets implanted in, the uterus after about 7 days of fertilization., Upon implantation, the endometrium undergoes changes, referred to as the decidual reaction, during which, endometrium thickens and its stromal cells enlarges to, become decidual cells which secrete prolactin., Decidual reaction helps prevent invasion of, trophoblast beyond the endometrium., Gastrulation, characterised by cell movement or, morphogenetic movement, is a process by which, single layered blastula is transformed into gastrula, larva with three primary germ layers., During gastrulation, blastocoel is obliterated, and a new cavity archenteron or gastrocoel is, formed from chordamesoderm (= the area of, mesoderm that forms the notochord)., Gastrulation begins with the formation of, blastopore and ends with the development of, neural tube., Primary germ layers are ectoderm, mesoderm and, endoderm., Endoderm in a mammalian embryo is formed, as the second layer by delamination of cells, from the inner cells mass. The endodermal cells, line the lume n of pr im itiv e gut (or, archenterone)., Formation of mesoderm initiates only after the, formation of endoderm as a distinct layer., Mesoderm proliferates from caudal end of, embryonic disc., After the emergence of the mesodermal layer, the, rest of cells of embryonic disc orient themselves in, layer to form ectoderm., Following gastrulation, the embryo passes through, the phase of neurulation, during which the, primordium of nervous system, the neural plate is, laid down., After gastrulation the cells of the 3 primary germ, layers give rise to the rudiments of future tissues, and organs., The establishment of the germ layers initiates, the final phase of embryonic development, i.e.,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 484, , l, , l, , l, , l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , organogenesis. The organogenesis involves, differentiation and specialization of groups of cells, in the individual germ layers., Epiboly involves the gradual growth and movement, of the prospective ectodermal blastomere, e.g., telolecithal eggs of Amphioxus and frog., Emboly involves the morphogenetic movement like, migration of ectoderm, mesoderm and notochord, cells from surface to interior., Invagination is the infolding of endodermal cells, into the body of blastula so as to form a cavity, the, archenterone., Active enrolling of endodermal and mesodermal, cells into interior of embryo is involution., Delamination means formation of second layer by, tangential division of surface cells., Convergence is the actual migration of blastomeres, from the outer surface to the external margin of, blastolip., Complete obliteration of blastocoel cavity marks, the end of gastrulation., , PLACENTA, l, , l, , l, , l, , l, , l, , EXTRAEMBRYONIC MEMBRANE, l, , l, l, , l, , l, l, , l, , l, , l, , Foetal membranes, also known as extra, embryonic membrane, are formed from, trophoblast in amniotes (reptiles, birds, mammals)., Four extra embryonic membranes are amnion,, chorion, allantois and yolk sac., Amnion is the inner foetal membrane that invests, the embryo and forms a space called amniotic cavity., It is filled with fluid called amniotic fluid., Amniotic fluid is useful for studying, chromosomal abnormalities of foetus as well as, sex determination., Chorion is the outer foetal membrane that also, takes part in the formation of placenta., Allantois is sac like, develops from gut of embryo,, supplies blood vessels to placenta. It helps in, respiration, nutrition and excretion., Allantois acts as extra embryonic kidney in reptile,, bird and prototheria and chorion acts as extra, embryonic lung in reptiles, birds and prototherians., The chorion contributes the placenta on the foetal, side, while uterine tissues supply the placenta on, the maternal side., Yolk s a c (th e f ir s t e x tr a e m br yonic, membrane) is the membranous sac attached to, embryo near allantois having yolk in egg laying, animals and forms corpuscles in mammals till, liver takes over., , l, l, l, l, l, l, l, l, l, , l, , l, , l, , Placenta is an intimate, mechanical connection, between foetus and uterus of mother for nutrition,, respiration and excretion., Placenta contains minute fingerlike projections, called villi. The uterine wall forms corresponding, depressions called crypts., The human placenta is haemochorial placenta, (in which maternal blood bathes foetal chorionic, villi directly), nondeciduous and metadiscoidal., Placenta also acts as an endocrine organs as it, secretes hormones such as estrogen, progesterone, and hCG that are essential for maintaining a, maternal physiological condition appropriate for, continued development of the conceptus., In simplest type of placenta, six barriers separate, maternal blood from foetal blood, Three barriers, are lost in human placenta., Umbilical cord is a flexible cord like structure, connecting the foetus at the navel with the placenta, and containing two umbilical arteries and one vein, that nourish the foetus and remove its wastes., The umbilical cord carries gases and nutrients to, the foetus from the placenta., Both type of blood vessels in umbilical cord are, surrounded by Wharton’s jelly., The delivery of child or child birth is called, parturition., Parturition is controlled by oxytocin and relaxin., Gestation period is the length of time from, conception to birth., Gestation period in humans is 9 months., Gestation period of 280 days is calculated from, time of last menstruation (hence 266 days)., In mammals, the onset of pregnancy inhibits, further ovulation., Two offsprings developed in the same uterus but, from fertilization of different ova are called, fraternal twins., When foetus fails to come out then the baby is, delivered by a surgical procedure called cesarian., This procedure was first performed on Caesar’s, wife during the Roman era., Abortion or miscarriage is the loss of embryo. It can, be due to breakdown of endometrium due to lowering, of progesterone secretion from corpus luteum., Stages of labor in parturition are – (1st) dilation of, cervix, (2nd) delivery of baby, and (3rd) delivery of, placenta.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ŇĐŕťŐňĽĘ– ▼ĚŢĚńŐőŇĚňŚ–, , According to, the nature, of foetal, membranes, According to, the degree of, connection of, maternal and, foetal tissues, , 485, , Yolk sac placenta, eg., Kangaroo & Opossum, Chorioallantoic placenta, eg. eutherians, Epitheliochorial placenta, e.g., horse, pig and ass, Syndesmochorial placenta, eg., camel, goat, sheep,, buffalo, cow, giraffe, Haemochorial placenta, eg., dog, cat, lion, tiger, Haemoendothelial placenta, eg., rat, rabbit., Diffuse placenta, eg., pig, (villi are diffused), Nondeciduous, placenta, (weak connection), , Types of placenta, in, Mammals, , Cotyledonary placenta, eg., cattle, sheep, (villi form cotyledons), Intermediate placenta, eg., camel, giraffe, (villi are diffused & cotyledons both), Zonary placenta, eg., dog, lion, tiger, (villi form girdle), , According to, nature and, distribution, of villi, , Deciduous, placenta, (strong connection), , Discoidal placenta, eg. bat,, bear, rat, rabbit (villi form disc), Metadiscoidal placenta, eg., man, monkey, (villi first scattered & afterwards form disc), , Contradeciduate placenta (too strong connection), eg., Perameles, Talpa, l, l, l, , l, , l, l, , l, , Lactogenesis is initiation of milk secretion under, the influence of prolactin hormone., Galactopoiesis is the maintenance of established, lactation., During lactation period woman does not concieve, because prolactin antagonizes the action of, gonadotropins on ovaries., The sensory stimuli of suckling inhibits dopamine, (or prolactin inhibiting hormone) secretion by the, hypothalamus which increases the release of, prolactin from the anterior pituitary which in turn, stimulates milk production., Colostrum (foremilk) releases first after the birth., Three to eight weeks old human embryo is most, sensitive to external factors (cigarette smoke, alcohol)., Gynaecology is the branch of medicine that deals, with the diseases and hygiene of women., , l, , l, , Obstetrics is the branch of medicine dealing with, the care of women during pregnancy, child birth, and the period during which they recover from, childbirth., Teratology is the study of abnormal foetal, development. Major birth defects are found in, approximately 3% of all deliveries. A teratogenic, agent is any chemical (drug), infection, physical, condition, or deficiency that, on foetal exposure,, can alter foetal morphology or subsequent function., Teratogenicity appears to be related to genetic, predisposition, (both maternal and embryonic), the, developmental stage of the foetus at the time of, exposure, and the route and length of administration, of teratogen., Teratogenic agents are ionizing radiation, drugs, and medication, maternal disorders like, phenylketonuria, diabetes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 486, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 51, , Growth, Repair, Regeneration,, Ageing & Death, l, l, l, , l, l, l, , l, l, , l, l, l, , l, l, , Growth is divided into periods of embryonic and, postembryonic growth., Early embryonic developmental stages constitute, prefunctional state., In postembryonic period of organism’s life, the, cells of the tissues and organs get differentiated for, specific functions. These cells lose the capacity of, division and perform physiological functions for, the survival of the organisms., Growth, regeneration and ageing may be described, as the postembryonic developmental events., Growth is irreversible increase in size, increase in, weight, synthesis of new protoplasm., Substances synthesized during growth are, protoplasmic (nucleus and cytoplasm) and, apoplasmic (substance present outside the cell like, matrix of bone marrow or fibres of connective tissue, or even water)., Growth is always associated with differentiation., Differentiation is a change in the anatomy or, physiology of a single cell or cell or group of cells, (tissue) in multicellular organisms as it matures, into a specialised cell or tissue., Growth occurs when anabolism (synthetic, activities) is higher than catabolism., Degrowth takes place when catabolism is higher, than anabolism., Quantitative growth may be defined in terms of, individual growth (a permanent increase in the, biomass of a cell or organism) or population, growth (an increase in the number of individual in, a population)., The steps involved in cellular growth are cell, division, cell enlargement and cell differentiation., Cell division is cell multiplication (e.g., lens cells, grows by multiplication), cell enlargement is, increase in volume of cell without division (eg.,, , l, l, l, l, , l, , l, , l, , l, , l, , l, , cardiac & skeletal muscles, neurons which grows, by extension & growth of axon and dendrites)., Cell growth occurs during postmitotic phase and, interphase., During interphase, cells grow by synthesis of new, materials such as nucleic acids and proteins., Cell multiplication and growth can be studied well, in tissue or in culture of unicellular organisms., The growth of multicellular organism falls under, three categories – auxetic, multiplicative, accretionary growth and appositional growth., Auxetic growth is growth in which volume of body, increases due to the growth of cells without any, increase in the number of cells. It occurs in, nematodes, rotifers and tunicates., Multiplicative growth is the growth of the body, due to increase in the number of cells. The cells, divide mitotically to increase their number but their, size remains the same. Eg. the prenatal growth or, embryonic development of higher vertebrates., Growth due to mitotic multiplication of reserve, cells occurring in specific locations of the body is, accretionary growth. Eg. postembryonic growth, of animals., Examples of accretionary growth are, erythropoietic tissue, matrix secreting chondrocytes, and osteocytes., Appositional growth involves the addition of new, layers on the previously formed layers. For example,, the addition of lamellae in the formation of bone., It is the characteristic mode of growth in rigid, materials., On the basis of body proportions, pattern of, growth are of two types isometric growth (an, organ grows at the same rate as the rest of the body,, as the organisms grows, the external form of body
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ŕŐţŚĺΘ– ☻ĚőďĽŕΘ– ☻ĚĹĚňĚŕŐňΘ– ○ĹĚĽňĹ– ·– ▼ĚďŚĺ, , l, l, l, , l, , l, , l, , l, l, l, l, l, l, l, l, l, l, l, l, l, l, , does not change, eg., fish and certain insects) and, allometric growth (an organ grows at a rate, different from that at which the body grows, as the, organisms grows, the external form of body, changes, eg. mammal)., The usual shape of growth curve is sigmoidal., Growth curve is the graphic representation of, growth against time., The increase in weight of an animal if plotted, against time, a characteristic S shaped curve is, obtained. It is called sigmoid curve or growth curve., The sigmoidal or Sshaped growth curve is the, characteristic growth curve of all higher animals, including man., The sigmoid curve represents the growth pattern, of all organisms, plants or animals, unicellular, or multicellular forms at various interval., The sigmoid curve consists of the following stages –, lag phase (little growth means slow increase in, body weight); exponential/acceleration phase/log, phase (maximum growth, the point where the, exponential growth begins to slow down is known, as inflexion point); senescent/decelerating phase, (declining growth i.e. growth with decreasing rate);, and steady phase (no growth)., Exponential growth of cells is characteristic, feature of tissue culture cells., Auxanology is the study of growth., Maximum growth in human foetus occurs at the, age of four months., Growth in the first 1013 years of age is controlled, by thymosin., Growth at the end of childhood and during puberty, is controlled by thyroxine and GH., In human beings, growth stops completely at the, age of 2223 years., As compared to adult male, the female has more fat., In human beings brain shows the minimum, increase in weight from birth to adulthood., As compared to the whole body the head of the, new born human baby is 1/4., In human beings muscles shows the maximum, increase in weight from birth to adulthood., In animals growth rate is differential., Healing of cuts and wounds is called repair., Repair is effected by cell proliferation & migration., Regeneration is the ability to restore lost or, damaged tissues, organs or limbs. It is a common, feature in invertebrates, but far more limited in, , l, , l, l, l, l, l, l, l, , l, , l, , l, , l, , l, l, l, , 487, , most vertebrates., Two principal categories of animal regeneration, are: reparative regeneration and restorative, regeneration., Reparative regeneration is common in both, invertebrates and vertebrates., Animals with higher and complex organization have, reparative regeneration only., Restorative regeneration is common in some, invertebrate groups., Animals with simple organization have greater, power of restorative regeneration., Hydra and Planaria have the power of repetitive, regeneration., Based on cellular mechanism, regeneration is of, two types : morphallaxis and epimorphosis., T. H. Morgan for the first time recognise the, following two mechanisms of regeneration in, animals., Morphallaxis (morphallactic regeneration) is the, reconstitution of the whole body from small, fragments., Morphallaxis occurs mainly by the repattening or, remodelling of existing tissues and the re, establishment of boundaries. It involves little new, growth, e.g. regeneration of Hydra and Planaria, from a segment of the animals., Epimorphosis (epimorphic regeneration) is the, regeneration of lost body part through, dedifferentiation of adult structures, cell, proliferation and differentiation, e.g. regeneration, of lost limb in salamander (amphibian)., During epimorphosis, the epidermis spreads and, covers the wound. In the next few days a mass of, cells forms a regeneration bud or blastema. Finally, the blastema undergoes differentiation to restore, internal and external structure of lost limb., Blastema is the accumulation of cells and formation, of a bud at the site of amputation., Regeneration of a limb or a tail is an example of, epimorphosis., Regeneration of a lost limb occurs in two major, steps first dedifferentiation of adult cells into a, stem cell state similar to embryonic cells and second,, development of these cells into new tissue more or, less the same way it developed the first time. Some, animals like Planarians instead keep clusters of non, differentiated cells within their bodies, which migrate, to the parts of the body that need healing.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 488, , l, , l, l, l, l, l, l, l, l, l, l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Phases of wound healing are preblastema stage,, phase of blastema formation (includes phase of, dedifferentiation and pseudodifferentiation) and, redifferentiation and morphogenesis., The process of regeneration was first discovered, in Hydra by Trembley., Liver possesses good regenerating power in, mammals., Regeneration is controlled by the neural and, hormonal factors., Sponge has the greatest regenerating capacity., The voluntary casting off a part of the body when, an animal is attacked is known as autotomy., Autotomy is recorded in legs of crabs, tail of, lizards and arms of star fishes., Salamander is capable to regenerate limbs, tail and, external gills., Regeneration is possible in tadpoles for, amputated tail and hindlegs., Regeneration that produces a part different from, the lost part is called heteromorphosis., Power of regeneration in flatworm is highest at, head region and lowest towards the tail end., To take over the function of one removed organ is, a type of compensatory regeneration or, compensatory hypertrophy (eg. mammalian liver)., Human body regularly loses cells in the region of, skin surface, lining of gut and red blood cells., During regeneration, differentiation, cell division,, cell movement and tissue differentiation takes place., Ageing is the time related deterioration of the, Table : Regenerative ability in animals, Parts regenerated, Animals, The whole body, Sponges, Hydra, and, Planaria, Few body segments, Earthworms, Mollusca, Parts of eye, eyestalk,, head, foot, etc., Insects, crustaceans, Limbs, and spiders, Starfishes, Arms, Salamander and, Limbs, tail, external, Axolotl, gills, jaws, intestine, etc., Tadpoles, Tail and hindlegs, Fishes, Fins, Lizards, Tail, Birds, Beak, Mammals, Liver, , l, l, l, l, , l, l, l, , l, , l, l, l, l, , l, l, , physiological functions necessary for survival and, fertility. It is largely caused by wear and tear., Pigment of ageing is lipofuschin., With ageing an impairment of physiological, functions occurs. It is called senescence., The number of years an individual can expect to, live is known as life expectancy., During ageing different organs and organ systems, show decline in functioning like –, –, Heart grows slightly larger with age and, maximal O2 consumption during exercise, declines., –, The vital capacity of lungs decline by 40%, between the age of 20 and 70., –, Brain loses some cells (neurons) and other, become damaged., –, Kidney gradually becomes less efficient and, bladder capacity declines., –, There is a redistribution of fat to deeper part, of the body. In woman it occurs in hips and, thighs and in man it is in abdominal area., –, There is a decline in muscle mass., –, Difficulty in focussing close up in the 40s and, inability to distinguish fine details may begin, to decline in 70s., –, Impairment in hearing ability with age., The bones of old persons become brittle due to, accumulation of calcium., During ageing, collagen present in intercellular, spaces become less permeable, rigid and insoluble., Disappearence of elastic fibres in association of, collagen protein results in wrinkling of the skin, in old age., Vitamin C is required for collagen synthesis thats, why vitamic C is much required in old age for the, maintenance of long bones, teeth and cartilage., On an average, 20% of nerve cells in the brain die, at the age of 70 years., Ageing is characterised by decline in metabolic, activity., The pumping capacity of heart in 70 years old, person as compared to 30 years old person is 65%., In an ageing person, there is an increase in collagen, rigidity of connective tissue and gradual alteration, of components of connective tissue., The part of the lung affected by ageing are, pulmonary arteries, pulmonary veins and alveoli., Ageing is faster in human males than in human, females.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ŕŐţŚĺΘ– ☻ĚőďĽŕΘ– ☻ĚĹĚňĚŕŐňΘ– ○ĹĚĽňĹ– ·– ▼ĚďŚĺ–, l, , l, , l, , l, , l, , l, , l, , l, , Dedifferentiation is the ability of differentiated or, specialized cells to change into cells capable of, division and grow., There are two types of theories for ageing :, programmed theories and damage or error, theories., Programmed theories hold that ageing follow a, biological timetable. It has three subcategories –, –, Endocrine theory holds that biological clock, act through hormones to control the pace of, ageing., –, Programmed senescence theory of ageing, is the result of the sequential switching on, and off of certain genes, causing programmed, cell death or apoptosis., –, Immunological theory According to this the, gradual atrophy and disappearance of thymus, gland disturbs the defence mechanism of the, body of combating germs and pathogens. With, the disappearance of this gland, the body, produces a great number of harmful abnormal, cells which cause the increased rate of the, change and destruction of tissues., Thymus is ductless gland located in the upper, anterior portion of the chest cavity. It is most active, during puberty after which it shrinks in size and, activity in most individuals and is replaced with, fat. The thymus plays an important role in the, development of the immune system in early life, and its cells forms a part of the body's normal, immune system., Damage or error theories maintains that the, environmental assaults to our systems make the, things to go wrong resulting in ageing., The damage or error theories of ageing includes, rate of living (metabolism), free radicals,, crosslinking, wear and tear, error catastrophe and, somatic mutation theories. Although ageing is, largely caused by wear and tear, it is also under, genetic control., Compromise theory advocates that ageing is an, outcome of interaction between the genes present, in the body of an individual and the environment, in which the individual lives., Metabolic theory postulates that the animals with, a high rate of metabolic activity age earlier and die, sooner than with a lower rate of metabolism., In wear and tear theory an organism has to achieve, a balance between the energy it puts into, reproduction and the energy it puts into, , l, , l, , l, , l, , l, l, , l, , l, l, , 489, , maintenance. The better the maintenance, the more, the organism approaches immortality. However,, some energy must always be put into reproduction, or the species would die., According to the free radical theory more free, radicals are produced with age which cause damage, by reacting with nucleic acids, lipids and proteins., Free radicals, highly reactive chemical compounds,, are ubiquitous in living organisms. Several enzymes, (superoxide dismutase, catalase, glutathione, peroxidase) and vitamins (vitamin E, C, carotenes), protect cells from oxidative attack., Hydra is an immortal organism not subjected to, ageing., Why Hydra is virtually immortal ?, Hydra is virtually immortal because interstitial, cells, present in the growth zone below the, tentacles, give rise to all other cells of body. With, the formation of new cells, old cells are pushed, towards the ends of tentacles and pedal disc, from, where they are shed outside. This process of cell, replacement is an endless process. It has been also, shown that if interstitial cells are destroyed, the, Hydra lives only for a few days., The branch of science which deals with the study, of ageing process is called gerontology. Father of, gerontology is Korenchevsky., Geriatrics is a branch of medicine that focuses on, health promotion and prevention and treatment of, disease and disability in later life., Average lifespan of women is longer than that, of men., Death is a biological phenomenon for maintaining, the balance of nature. It results in irreversible, breakdown of the body functions. Whatever the, cause, the death results from the failure of either, of heart, blood or nervous system. Natural death is, preceded by ageing., Clinical death means death of the brain which, results in no pulse or heart beat, no breathing and, fixed dilated pupil with no reaction to light. Brain, death occurs if no oxygen is supplied to it for, approx. 3 5 minutes., Thanatology is the scientific study of death that, almost involves death bed wishes., Conditions leading to brain death results in, swelling of brain tissue and a rise in intracranial, pressure, eventually shutting off all blood flow, within the skull.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 490, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 52, , Heredity & Variations, l, l, l, l, , Genetics is a branch of biology that deals with the, study of heredity and variations., The term genetics was first used by, W. Bateson (1905)., Gregor Johann Mendel is called the Father of, Genetics., Archibald Garrod is considered as the Father of, human genetics.`, , HEREDITY, l, , l, l, , l, l, l, l, l, , l, , l, , Heredity (like begets like) is the study of, transmission of characters from parents to, offspring or from one generation to the next., The characters that are passed from one generation, to the other are called hereditary characters., This occurs through transfer of chromosomes, from parents to offspring or individual to another., There is, therefore, chromosomal basis of, heredity., The character of heredity are fixed for a particular, organism., Mendel used the term factors for the heredity, unit which is now called as genes., Johannson termed the word phenotype and, genotype in addition to genes., The physical basis of heredity are genes while, chemical basis of heredity is DNA., The prevailing view of heredity in preMendelian, era was blending theory. This theory states that, individual would represent the mixture of both, the parents., Kolreuter (17331806) for the first time obtained, the experimental evidence that inherited traits, tended to remain discrete, but he was unable to, interpret them correctly., R.de.Graaf (16411673) suggested that both the, , l, l, , parent should contribute to heredity., Carl Nageli (1884) was the first to propose a theory, regarding heredity., Davenport and Davenport (1910) shows that skin, colour in human is a polygenic trait and is due to, atleast three separate genes., , Terms used in inheritance studies, l, l, l, l, l, , l, , l, , l, , l, l, , l, l, , Character is a well defined morphological or, physiological feature of an organism., Trait is the distinguishing feature of a character., Gene is the inherited factor that determine the, biological character of an organism., A pair of contrasting characters is called, allelomorph or allele., Term allele was given by W. Bateson for, alternative forms of same gene, e.g., T and t, Y, and y, R and r are pair of alleles., Dominant allele is one of the factor of an alleles, pair which can express itself whether present in, homozygous or heterozygous state, e.g., T (tallness, in pea), R (round seed in pea)., Recessive allele is the factor of an allele pair which, is unable to express its effect in the presence of its, contrasting factor in a heterozygote, e.g., t in Tt., The effect of recessive factor is expressed only, when it is present in the pure or homozygous, state, e.g., tt in dwarf pea plant., Wild allele is the one which was originally present, in the population and is dominant and widespread., The recessive allele is less common and might, have formed through mutation of wild allele. It is, thus called mutant allele., The diploid condition in which the alleles at a given, locus are identical is called homozygous or pure., In homozygous condition, organism have two, similar genes or alleles for a particular character
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘĚŕĚ꼌ť– ďňę– ♠ďŕĽďŚĽŐňř, , l, , l, l, l, l, l, l, l, , l, , l, l, l, , l, , l, , l, , l, l, l, l, , in a homologous pair of chromosomes, e.g., TT or, tt., Organisms containing two different alleles or, individual containing both dominant and recessive, genes of an allelic pair, e.g., Tt, is known as, heterozygous or hybrid., When only one allelic pair is considered in cross, breeding it is called monohybrid cross., When two allelic pairs are used for crossing it is, called dihybrid cross., Involvement of more than two allelic pairs in a, cross is called polyhybrid cross., Second stage of Mendel's experiment is called F1, generation or first filial generation., Third stage of Mendel's experiment is called second, filial or F2 generation., Complete penetrance is 100% ability of an allelic, combination to produce expected phenotype., Incomplete penetrance is failure of an allelic, combination to provide cent percent phenotypic, expression, e.g., polydactyly, diabetes mellitus., Hybrid vigour or heterosis is the superiority of, hybrid over either of its parents in one or more, traits., Genotypes is the sum total of heredity or genetic, make up., Phenotype is the external feature of organism., When two different genotypes due to different, environmental conditions give rise to same, phenotype, then one is said to be phenocopy of, the other., Monohybrid ratio is the ratio which is obtained, in F2 generation when a monohybrid cross is made, and the offspring of F1 generation are selfbred., Dihybrid ratio is a ratio which is obtained in the, F2 generation when a dihybrid cross is made and, the offspring of F1 generation are selfbred., Trihybrid ratio is the ratio obtained in F 2, generation raised from a trihybrid cross followed, by selfing of F1 individuals., When an individual is crossed with a parent it is, called back cross., When an individual is crossed with the homozygous, recessive parent it is called test cross., Monohybrid test cross ratio is 1 : 1 and dihybrid, test cross ratio is 1 : 1 : 1 : 1., Test cross is done for the following purposes –, –, To prove that 2 types of gametes are produced, , l, , l, l, l, l, , l, , l, , l, , 491, , by monohybrid, 4 types of gametes are, produced by dihybrid and 8 types of gametes, are produced by trihybrid., –, That these gametes are produced in equal, number., –, Genotype of the offspring can be tested., If in one cross, individual X is used as male and, Y as female and in the next cross Y is used as male, and X as female, it is called reciprocal cross., The portion or region on chromosome representing, a single gene is called gene locus., The alleles of a gene are present on the same gene, locus on the homologous chromosomes., All the genotypes of all organisms in a population, form the gene pool., Pure line or pure breeding line is a strain of, individuals homozygous for all genes considered., The term was coined by Johannsen., Punnet square is a checker board which was, devised by R.C. Punnet and used to show the result, of a cross between two organisms., Genome is a complete set of chromosomes where, every gene chromosome is represented singly as in, a gamete., A single genome is present in haploid cells, two, in diploid cells and many in polyploid cells., , Mendel’s principles of inheritance (Mendelism), l, , l, l, l, , l, , l, , l, , The first scientific study leading to formulations of, law of inheritance was carried out by Gregor, Johann Mendel., Mendel first represented his rules of inheritance, in 1865., Mendel was a monk in Austria., Mendelian inheritance or Mendelian genetics is, a set of primary tenats that underlie much of genetics, developed by G. Mendel in the latter part of 19th, century., Mendel’s laws of Heredity are described in his paper, “Experiments on Plant hybridization” which was, published in the fourth volume of “Annual, proceedings of Natural History Society of, Brunn”., Mendel’s based his theory on experiments involving, cross pollination between two plants or self, pollination with a single plant., Mendel had conducted hybridization experiments, in garden pea, Pisum sativum.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 492, , l, , l, l, , l, l, , l, , l, , l, l, l, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Mendel’s laws were rediscovered simultaneously, by three great scientists namely Huge de vries,, Erich Von Tschermak and Carl correns., The number of characters studied by Mendel in pea, plant was seven., The number of chromosomes in Pisum sativum is, 14 (2n)., Mendel restricted his experiments to one or few, pairs of contrasting traits in each experiment., Self fertilization in pea can be prevented by, removing anthers (emasculation) before pollen, grains mature., Mendel selected garden pea for his experiment, because –, –, It has a number of well defined contrasting, characters., –, It is having bisexual flowers., –, It shows predominantly self fertilisation, (autogamy)., –, Hybridisation or crossing is easy in pea., –, It is having short life span., Mendel’s experiment involved 4 steps as –, selection, hybridization, selfing and calculations., –, First he selected a true breeding variety., –, Then he cross pollinated two contrasting true, breeding varieties to get F1 generation, –, Then he self pollinated F1 offsprings to get F2, and self pollinated F2 to get F3 generation., His results led to the formation of laws of genetics, later., Mendel performed monohybrid and dihybrid, crosses and gave three principles of inheritance., Mendel’s three principles of inheritance are –, –, Law of dominance, –, Law of segregation or law of purity of gametes, –, Law of independent assortment., Law of dominance states that only one factor, expresses itself in F1 generation., F2 expresses both the dominant and the hidden, recessive factor in the ratio of 3 : 1 in the, monohybrid cross., In a hybrid where both the contrasting alleles are, present, only one factor/allele called dominant is, able to express its effect while the other factor /, allele called recessive remains suppressed in F1, generation. This is called Law of dominance., Exception to principle of dominance are, , l, l, , l, l, , l, l, , l, , l, l, , l, , l, , l, , l, l, l, , incomplete dominance and codominance., Incomplete dominance is the phenomenon where, dominant allele do not completely express itself., Incomplete dominance is not blending inheritance, because parental characters reappear in F 2, generation., This phenomenon was first studied in flower colour, of Mirabilis jalapa or four O’clock plant., The phenotypic as well as genotypic monohybrid, ratio in F2 generation in incomplete dominance is, 1 : 2 : 1 i.e., pure dominant : hybrid : pure recessive., F1 generation expresses a phenotype which is, intermediate between those of the parent., When blue Andalusian are crossed among, themselves, they produce splashed white, blue and, black offspring in the ratio of 1 : 2 : 1 due to, incomplete dominance., Overdominance is another dominance relationship, in which the phenotype of heterozygote is not equal, to that of either homozygote., Heterozygote with overdominance alleles have a, phenotype more extreme than either homozygote., In codominance, both allelic genes of a genetic, trait are equally expressive i.e., the dominant, character is not able to suppress the recessive, character and thus both the characters appear side, by side in F1 hybrids., Principle of segregation states that, “when a pair of, contrasting factor or gene are brought together in, a hybrid; these factors do not blend or mix up but, simply associate themselves and remain together, and separate at the time of gamete formation”., This law can also be stated as alleles pairs segregate, during gamete formation and the paired condition, is restored by random fusion of gametes during, fertilization., The above law is also known as “Law of purity, of gametes” because each gamete is pure in itself, i.e., having either T (i.e., gene for tallness) or t (i.e.,, gene for dwarfness)., Mendel formulated this law with the help of, monohybrid cross., The third principle of heredity is called the principle, of independent assortment., It states that the genes of different characters located, in different pairs of chromosomes are independent, of one another in their segregation during gamete, formation.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘĚŕĚ꼌ť– ďňę– ♠ďŕĽďŚĽŐňř–, l, , l, , l, , l, l, l, , l, , l, l, l, l, l, , l, , Independent assortment is not applicable for the, genes located on the same chromosome, i.e., linked, genes., Linkage is an exception of Mendelian principles, because characters studied in pea plant by him were, located on different chromosomes or the distance, separating the syntenic loci was sufficiently great, so that the genes were inherited as though they were, on separate chromosomes., The genes controlling the seven pea characters, studied by Mendel are now known to be located on, four chromosomes (1, 4, 5, 7)., Mendelian recombinations were mainly due to, independent assortment., Test cross is also applicable to dihybrid cross., A dihybrid test cross give a 1 : 1 : 1 : 1 ratio,, indicating that two pairs of factors are segregating, and assorting independently., Atavism is the phenomenon during inheritance, wherein a character remains hidden for several, generation and then suddenly gets expressed, unchanged in one or more individuals., Monohybrid phenotypic ratio is 3 : 1., Monohybrid genotypic ratio is 1 : 2 : 1., Dihybrid genotypic ratio is 1 : 2 : 1 : 2 : 4 : 2 :, 1:2:1, Dihybrid phenotypic ratio is 9 : 3 : 3 : 1, Importance of Mendelism are –, –, On the basis of Mendelism, different breeds, in animals and varieties of plants have been, produced., –, Science of eugenics (development of superior, progeny) is based on Mendelism., –, On the basis of Mendelism, heterosis has been, utilised in different organisms., Mendel was successful in his experiments with, pea plant because, –, He selected pure breeding, one or two, characters at one time for his breeding, experiments., –, He took those traits which did not show, linkage, interaction or incomplete dominance., –, He used statistical methods and law of, probability analysing his results., –, Pea had contrasting expression of traits., –, Pea can be cross bred manually but itself, undergoes self breeding., , –, , 493, , There is little chance of pollen contamination., , Gene interaction, l, , l, l, l, , l, , l, , l, , Gene interaction is the modification of normal, phenotypic expression of genes due to their, alleles and non allelic genes., Gene interaction is a post mendelian discovery., Gene interaction is of two types – intragenic and, intergenic., In intragenic interaction, two alleles of a gene, which are present on the same gene locus on the, two homologous chromosomes, react to produce, modified phenotype. Eg., incomplete dominance,, codominance, multiple alleles and lethal genes., Intergenic interaction is one where two or more, independent genes belonging to same or different, chromosomes interact to form a different, expression., Intergenic interaction includes epistasis, duplicate, genes, complementary, genes, supplementary genes,, inhibitory genes etc., Modified Mendelian ratio are expressed as, 9 : 7, 9 : 3 : 4, 12 : 3 : 1, 15 : 1, 13 : 3., , Incomplete dominance, l, The main objection to the Mendel’s principle of, genetics was incomplete dominance., l, Incomplete dominance is the phenomenon where, dominant allele do not completely express itself., l, Correns discovered incomplete dominance and, cytoplasmic inheritance., l, Incomplete dominance is not blending inheritance, because parental characters reappear in F 2, generation., l, This phenomenon was first studied in flower colour, of Mirabilis jalapa or four O'clock plant., l, The phenotypic as well as genotypic monohybrid, ratio in F2 generation in incomplete dominance is, 1 : 2 : 1 i.e., pure dominant : hybrid : pure, recessive., l, F1 generation expresses a phenotype which is, intermediate between those of the parent. Eg pink, flowers are obtained when red and white flowers, plants are crossed., Codominance, l, Codominance is the phenomenon of two alleles, lacking dominant recessive relationship and both, express themselves in the organisms., l, The codominant alleles are able to express
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 494, , l, , ŕďőĽę– ĐĽŐńŐĹť, , themselves independently when present together, and codominance has been reported in roan, characters of cattle., The codominant alleles are shown with same capital, letter but with different superscripts like IAIB for, allele in human blood group AB and HbA HbS for, normal and sickle celled erythrocytes., , Multiple alleles, l, More than two alternate forms of a gene present, on the same locus are called multiple alleles., l, There is absence of crossing over in multiple alleles, and the mode of inheritance in case of multiple, alleles is called multiple allelism., l, The well known example of multiple allele in human, is blood group, which also shows codominance., l, Landsteiner discovered the three blood groups in, man (A, B and O)., l, Blood group AB was discovered by de Castello, and Steini (1902)., l, There are more than two alleles of the same gene, e.g. 15 alleles for eye colour in Drosophila., l, Multiple alleles express different alternatives of, the same characters., l, Different alleles show codominance, dominance, recessiveness or intermediate dominance amongst, themselves., l, They however, follow Mendelian pattern of, inheritance., Lethal genes, l, A lethal gene can be defined as a gene whose, phenotypic effect is sufficiently drastic to kill, the bearer., l, Lethal genes control some vital functions of the, organism and cause death of the organisms in, pure recessive or pure dominant form., l, Lethal gene were first discovered by Cuenot., l, In absolute lethality individual dies in embryonic, stage. For eg. yellow fur in mice., l, In sublethality individual dies before reproductive, maturity. For eg. sickle cell anaemia., l, In delayed lethality individual dies after sexual, maturity., l, Albinism in corn is due to lethal genes., l, Inhibitor or suppressor genes are nonlethal gene, without any expression of its own but suppress, or inhibit the expression of a nonallelic gene., l, For example, in Rice Igene inhibits the expression, , of dominant purple colour gene (P) so that the leaves, are green in its presence (IP). Green leaves also, occur when the leaf colour gene is recessive (iipp)., A cross between IIPP and iipp (both green) yields, hybrid greens (IiPp) which on self breeding form, 3 purple to 13 green plants., Epistasis, l, Epistasis can be defined as the phenomenon of, gene interaction whereby one gene interferes, with the phenotypic expression of another non, allelic gene or genes., l, The gene or locus which suppresses or masks the, action of a gene at another locus is called epistatic, gene., l, The gene or locus whose expression is suppressed, by an epistatic gene is called hypostatic gene., l, Hypostastasis is the phenomenon by which the, effect of a gene gets suppressed due to the presence, of a non allelic gene., l, An epistatic hypostatic relationship between two, loci is similar to a dominant recessive relationship, between alleles at a particular loci., l, A dominant epistatic allele suppress the expression, of a non allelic gene, the latter may be dominant, or recessive., l, The dihybrid ratio for dominant epistasis is, 12 : 3 : 1., l, In recessive epistasis, epistatic gene suppresses, the expression of nonallelic gene only when it is, in homozygous recessive state., l, Recessive epistasis or supplementary gene ratio is, 9 : 3 : 4 (dihybrid ratio)., l, 13 : 3 is dominant recessive epistasis ratio., l, In a cross between black (CCaa) and albino (AAcc), guinea pig F 2 exhibits 9 agouti :, 3 black : 4 albino., Complementary, duplicate, supplementary and, polymetric genes, l, If two genes present on different loci produce the, same effect when present alone but interact to form, a new trait when present together are called, complementary genes., l, Bateson and Punnet (1906) observe, complementary gene in Lathyrus odoratus., l, There are two white varieties of Sweet pea (Lathyrus, odoratus) controlled independentally by two, different genes (Cpp and ccP).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 495, , ŘĚŕĚ꼌ť– ďňę– ♠ďŕĽďŚĽŐňř–, , Table : Expected ratios in different types of crosses with examples, Characters, 1., , Monohybrid cross, , 2., 3., 4., 5., 6., , Dihybrid cross, Incomplete dominance, Complementary genes, Supplementary genes, Modified supplementary, genes (collaboration), Dominant epistasis, Recessive epistasis, Duplicate genes, Polymeric gene (duplicate, genes with cumulative, effect), Supressor gene (Inhib, itor gene), , 7., 8., 9., 10., 11., l, , l, l, , l, l, , l, l, , Expected ratios, , Example, , Phenotypic : 3 : 1, Genotypic : 3 : 1, Phenotypic : 9 : 3 : 3 : 1, 1:2:1, 9:7, 9:3:4, , Pisum sativum, Pisum sativum, Pisum sativum, Mirabilis jalapa, Lathyrus odoratus, Coat colour in mice, , 9:3: 3:1, 12 : 3 : 1, 9:3:4, 15 : 1, , Poultry birds – comb pattern, Fruit colour in Cucurbita, Coat colour in mice, Fruit shape in Capsella bursapastoris, , 9:6:1, , Cucurbita pepo, , 13 : 3, , Leaf colour in rice, , Dominant gene C produces an enzyme that converts, the raw material for flower pigmentation into, chromagen. Dominant gene P produces another, enzyme that oxidises chromagen into purple, coloured anthocyanin. Therefore, the dominant, alleles of both the genes are required for expression, of flower colour., Complementary gene ratio is 9 : 7., There are two (or more) independent genes found, on different chromosomes which produce the same, or nearly similar phenotypic effect in the dominant, state, producing same intensity of effect even when, present together, so that dominant phenotype is more, abundant. Such genes are called duplicate genes, or pseudoalleles., Duplicate dominant gene ratio is 15 : 1., Supplementary genes are two nonallelic genes in, which one type of gene produces its effect whether, the other is present or not and the second, (supplementary) gene produces its effect only in, the presence of the first usually forming a new, trait., F2 dihybrid ratio is 9 : 3 : 4., Polymeric genes are duplicate genes with, cumulative/additive effect, i.e., two independent, dominant genes (whether homozygous or, heterozygous) having similar phenotypic affect, , l, , individually but produce a new cumulative effect, (similar in homozygous and heterozygous states), when present together., 9 : 6 : 1 is the ratio of duplicate genes with, cumulative effect., , Pleiotropic genes, l, , l, , l, l, , l, , l, , When a gene affects many aspects of phenotype or, controls several phenotypes, it is said to be, pleiotropic genes and this phenomenon is called, pleiotropy., When a number of related changes are caused by, a pleiotropic gene, the phenomenon is called, syndrome., Pleiotropy is expressed by sickle cell anaemia,, haemophilia, etc., Sickle cell anaemia disease is caused when a gene, responsible for haemoglobin produced by recessive, alleles differs in one amino acid. It incorporates, valine in place of glutamic acid., In human beings, Marfan’s syndrome,, characterised by long limbs, slender body,, hypermobility of joints, lens dislocation and, susceptibility to cardiac diseases are caused by, single pleiotropic gene., Galton coined the term eugenics., , Pedigree analysis, l, , A record of the occurrence of a trait in several
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 496, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , generation of a human family is called Pedigree, analysis., Male member in pedigree are shown by square, and female by circle O., Siblings are represented horizontally on a line in, order of birth., Solid symbols (l) represent the traits being invested, and open symbols O or represent the normal traits., Pedigree analysis helps in identifying the, inheritance of specific traits and their possibility of, showing up in the offsprings. It is of great, significance in the study of genetics., , Quantitative (polygenic) and qualitative, inheritance, l, , l, l, , l, , l, l, , l, , l, l, , l, , Quantitative or polygenic inheritance is that type, of inheritance in which the complete expression of, a trait is controlled by two or more genes in which, a dominant allele of each gene contributes only a, unit fraction of a trait and the total phenotypic, expression is the sum total/additive/cumulative, effect of all the dominant alleles of genes/, polygenes., In quantitative inheritance traits are expressed in, continuous fashion., The genes involved in quantitative inheritance are, called polygenes or cumulative genes., A polygene is defined as a gene where a dominant, allele controls only a unit or partial quantitative, expression of a trait., NilssonEhle (1908) was first to experimentally, prove quantitative inheritance., Polygenic inheritance is also called quantitative, inheritance since so many grades between two, extremes appear, eg. skin colour in human,, intelligence etc., Davenport and Davenport (1910) shows that skin, colour in human is a polygenic trait and is due to, at least three separate genes., In quantitative inheritance traits are expressed in, continuous fashion., Qualitative inheritance is that type of inheritance, in which one dominant allele influences the, complete trait so that two such alleles do not, change the phenotype., Monogene is a gene in which one dominant allele, , controls the complete or qualitative expression of, a trait., , VARIATIONS, l, , l, l, , l, , l, l, , l, , l, , l, , l, , l, , The characteristic differences exhibited by the, individual of the same species, race and family is, called variations., Variation caused due to genetic difference are called, genetic variation or heredity variations., The variation caused due to environmental factors, and which is not fixed is called environmental, variation., Heredity variations are transmitted from, generation to generation whereas environmental, variation are temporary and do not relate with, last or next generation., Heredity variation within a progeny results due to, sexual reproduction., Somatic variations affect the somatic or body cells, of the organisms and these die with the death of the, individual and thus are non inheritable., Somatic variations are also called modifications, of acquired characters because they are acquired, by an individual during its life time., Somatic variations are caused by three factors, namely environment, use and disuse of organs, and conscious efforts., Continuous variations are fluctuating variations, which oscillate around a mean or average of the, race, variety and species., Continuous variations are also called, recombinations because they are formed due to, recombination of alleles caused by –, –, Chance separation/segregation of chromosomes, at the time of meiosis (sporogenesis in plants, and gametogenesis in animals)., –, Crossing over or exchange of chromatid, segments during meiosis., –, Chance aggregation of chromosomes during, fertilization., Continuous variations are of two types –, –, Meristic, influencing number of parts like, number of grains in an ear of wheat, number, of tentacles in Hydra., –, Substantive, influencing appearance like, height, colour, yield of milk or eggs.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘĚŕĚ꼌ť– ďňę– ♠ďŕĽďŚĽŐňř–, l, , l, , l, , l, , Discontinuous variations are mutations which are, sudden, unpredictable inheritable variations not, connected with the average by any intermediate, stages., Discontinuous variations are source of all germinal, variations and most of evolution., Discontinuous variations are caused by, chromosomal aberrations, change in, chromosome number and gene mutations., Depending upon the effect, they are of two types –, –, Indeterminate variations, which occur in any, conceivable direction and to any degree., –, Determinate variations, which are variations, in particular direction with selective or, adaptive importance and are also called, orthogenic variations., Variations make some individual better fitted in, , l, l, l, , l, l, l, , l, , 497, , the struggle for existence., They help the individuals to adapt themselves, according to the changing environment., Discontinous variations produce new traits in the, organisms., Variations allow breeders to improve races of useful, plants and animals for increased resistance, better, yield, quicker growth and lesser input., They constitute the raw material for evolution., Variations gives each organism a distinct, individuality., Because of variations species do not remain static., Instead, they are slowly getting modified forming, new species with time., Preadaptations caused by the presence of neutral, variations are extremely useful for survival against, sudden changes in environment, e.g., resistance, against a new pesticide or antibiotic.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 498, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 53, , Genes & Chromosomes, GENES, l, l, , l, , l, l, l, , l, , l, , l, l, , l, , l, , l, , Gene is the basic unit of inheritance that specifies, the expression of a particular trait., According to T.H. Morgan –‘Any particle on the, chromosome which can be separated from other, particles by mutation or recombination, is called, a gene’., Chemical nature of gene suggests that genes are, catalysts which bring about reaction without being, changed or consumed., Ultimate unit of recombination, mutation and, self reproduction is gene., The total number of genes in human is about 30,000., Gene should be able to express in genetic expression, by transcription to mRNA and finally to produce, proteins., Term ‘gene’ was given by Johannsen (1909) for, any particle to which properties of Mendelian factor, or determiner can be given., Genes act by producing enzymes, i.e. each gene in, an organism produces a specific enzyme, which, controls a specific metabolic activity., Gene is chemically DNA, but the length of DNA, which constitutes a gene, is controversial., 3 terms, i.e. cistron, muton and recon were given, by Seymour Benzer to explain the relation between, DNA length and gene., Cistron is that particular length of DNA which is, capable of producing protein molecule or, polypeptide chain or enzyme molecule., Muton is that length of DNA which is capable of, undergoing mutation. Muton is having one or part, of nucleotide., Recon is that length of DNA, which is capable of, undergoing crossing over or capable of, , recombination. Recon is having one or two pairs, of nucleotides., , Types of genes, Transposons or jumping genes, l, Transposons or jumping genes (Mc Clintock 1951, in Maize; Hedges and Jacob, 1974) are those DNA, segments which can pass from one place to another, in the genome., l, At their ends, transposons have silmilar or inverted, repetitive DNA sequences. The sequences can be, cleaved by an enzyme transposase., Retroposons, l, The term retroposon was given by Rogers (1983), for DNA segments which are formed from RNA, (RNA origin) or which are formed by reverse, transcription under the influence of reverse, transcriptase enzyme or RNA dependent DNA, polymerase enzyme. i.e.,, Reverse transcription, RNA ¾¾¾¾¾¾, ® DNA(Retroposon), Split genes or interrupted gene, l, R.J.Robert and P.A. Sharp (1977) discovered split, genes (gene with introns) in eukaryotes for which, they were awarded Noble Prize in 1993., l, Split genes, present in eukaryotes have coding gene, which are not continuous but are interrupted by, noncoding sequence., l, Two kinds of alternating segments in the split, genes are – exon and intron., l, Exon contains coding nucleotides sequence which, are ultimately translated into polypeptides., l, Exons carry genetic information., l, Intron contains noncoding nucleotide sequence, which are not translated into polypeptide., l, Eukaryotic genes without introns are called exonic
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 499, , ◙ĚňĚř– ·– ►ĺŕŐŇŐřŐŇĚř, , l, , l, , l, l, , l, , genes (non split gene), eg. histone gene, interferon, gene., Certain eukaryotic exonic genes are called, processed genes which lack both intron and, promotors. Therefore they are nonfunctional., Nonfunctional or inactive DNA present in, eukaryotes is known as repetitive DNA or excess, DNA., Gene splicing is developed by Cohen and Boyer, (1973)., Splicing involves : (i) removal of intron portion, and fusion of exons to produce continuous gene or, mRNA, and (ii) uniting foreign gene with bacterial, genome for producing specific substances (eg., insulin)., Functional eukaryotic m RNA transcribed by exon, is formed by splicing., , Pseudogenes or false gene and multiple genes, l, Pseudogenes are nonfunctional genes., l, Pseudogenes are unable to produce functional, products due to inactivation of promotor region,, presence of intervening nonsense codons insertions, or deletions. E.g. several SnRNA genes., l, Pseudogenes are useless to the organisms and, considered to be defective copies of functional, genes (cistrons)., l, Pseudogenes are reported in Drosophila, mouse, and human beings., l, Multigenes or multiple gene family is a group of, nearly similar genes which produces tissue and time, specific products. Eg. globin gene family., l, In a cell hardly 10% of the gene are active and, 90% being inactive., Inducible genes or repressible genes, l, Non constitutive genes are those genes which can, be switched on or off as per requirements., l, They are of two kinds – inducible (remain repressed, but are switched on in the presence of an inducer, chemical) and repressible (remains active till, switched off by a chemical)., House keeping genes, l, There are other genes which are always expressed,, are called constitutive genes or housekeeping, genes and their common functions are required in, all types of cells, e.g. RNApolymerasedetermining, genes such as tRNA and rRNA., , CHROMOSOMES, l, , l, , l, , l, , l, l, l, , Chromosomes are oval, rod or thread like DNA, complexes which function as hereditary vehicles, because they store, replicate and transcribe coded, hereditary information., The relationship between the behaviour of, chromosomes and the behaviours of Mendels, factors was first recognized by W.S. Sutton and, Boveri in 1902 or Chromosome theory of, inheritances was proposed by Sutton and Boveri, (1902)., This theory states that chromosome are vehicle of, heredity information and expression as genes are, present over them., Chromosomes are filamentous body which are, typically present in the nucleus and become visible, during cell division., Chromosomes are not visible in the active nucleus, due to their high H2O content., Number of chromosomes in definite nucleus is, diploid., Complete haploid set of chromosomes of a species, is genome., , Prokaryotic and viral chromosomes, l, l, l, l, l, l, l, , l, l, l, , Prokaryotic chromosomes are represented in the, form of short, simple, single DNA molecule., Nucleoid is the compact mass of irregularly folded, DNA molecules in bacteria., Plasmids were discovered by Lederberg and Hayes, (1952)., Plasmids are the most widely used cloning vectors, in the techniques of gene manipulation in bacterium., Tiplasmid of Agrobacterium is widely used in, plants., Plasmid can replicate, like nucleoid, independently, of main genome., Plasmids carry gene for sexuality like fertility, factor, antibiotic resistance like chloramphenicol,, tetracycline etc., Nif (nitrogen fixation),, colicinogenic factor for synthesis of bacteriocidal, & bacteriostatic chemicals., The process of replication of plasmid DNA other, than initiation is controlled by bacterial gene., Viral nucleoid are packed into single hereditary, unit called viral chromosome., Virion is the unit of a virus particle composed of, a nucleic acid core and a protein coat.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 500, , l, l, , l, l, l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , The term ‘virion’ was introduced by Lwoff,, Anderson and Jacob in 1959., Virion is a simple, structurally complete (mature), virus particle., Virus consists of a nucleic acid core surrounded by, a protein coat., The protein coat that encloses viral genes is called, a capsid., Viruses usually have only one nucleic acid either, DNA or RNA. So viral genes are made of either, DNA or RNA., One of the best studied plant virus is Tobacco, Mosaic Virus (TMV)., TMV was the virus first discovered. Genetic, material of TMV is RNA., DNA viruses possess DNA as the genetic material., Many of the animal viruses like poxviruses,, adenoviruses, herpes viruses and majority of, bacteriophabge are DNA viruses., Most RNA viruses possessing RNA as the genetic, material carry a gene for an enzyme that uses viral, RNA as a template in the synthesis of more viral, RNA. This enzyme is RNA replicase., Among animal viruses paramyxoviruses (Mumps, and Measles), orthomyxovirus (Influenza),, rhabdovirus (Rabies), togavirus (Dengue fever),, reovirus (illness of respiratory tract) and, picornavirus (Polio) are RNA viruses., RNA DNA viruses are also called as retroviruses, (retro = turning back), they have their genes, the, genetic material in the form of single stranded RNA., Retrovirus possesses the gene that codes for reverse, trancriptase, an enzyme (carried in the viral coat), that causes synthesis of a double stranded DNA, molecule from single stranded RNA template., Temin (Nobel Prize 1975) discovered that the Rous, Sarcoma Virus (RSV) do reverse transcription., There is a reverse flow of genetic information from, RNA to DNA., Viroids were discovered by T.O.Diener in 1971., Viroids are small single stranded circular RNA, molecules which infect higher plants., Viroid replication requires host encoded RNA, polymerase., [For more detail on bacteria and viruses refer, Chapters ‘Monera’ and ‘Viruses’.], , Eukaryotic chromosomes, l, , l, , l, l, l, , l, l, l, , l, l, l, l, l, l, , l, l, l, l, l, l, , Eukaryotic chromosomes were discovered by, Hofmeister (1848) in the pollen mother cells of, Tradescantia., The structures present in chromosomes are, centromere, secondary constriction, nucleolar, organizer, telomeres, chromonema and satellite., Chromatids are two subunits or similar threads, attached to each other to form chromosomes., The constricted region on the chromosome is called, centromere, kinetochore or primary constriction., Centromere is the central narrow nonstainable, portion of the chromosome to which the, spindle fibres attach during mitotic and meiotic, division., The two parts of a chromatids/chromosomes on, either side of centromere are called arms., The two arms may be equal (isobrachial) or unequal, (heterobrachial)., Depending on the position of centromere four, category of chromosome are recognised, i.e. metacentric, submetacentric, acrocentric and, telocentric., In metacentric the centromere is near the middle, of the chromosome., Metacentric chromosome appear V shaped during, anaphasic movement., In submetacentric centromere is present some, distance away from the middle., It appears L or J shaped during anaphase., In acrocentric centromere is situated near the end., It appears J shaped during anaphase., Telocentric centromere is truely terminal i.e, centromere is situated at the tip of the chromosome., The chromatids in a telocentric chromosome are, not divided in arms. The chromosomes remain rod, shaped., Telocentric appears I shaped during anaphase., Truely telomeric chromosome was reported by, Marks (1957)., In Trillium and Tradescantia all the chromosomes, are metacentric., In man, three types of chromosomes are found–, metacentric, submetacentric and acrocentric., In man chromosome number 13, 14, 15, 21, 22 and, Y have nucleolar organizer and satellite., Chromosome with two or more centromeres are, called dicentric and polycentric chromosomes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚř– ·– ►ĺŕŐŇŐřŐŇĚř–, l, l, , l, , l, , l, l, , l, l, l, , l, l, , l, l, l, l, l, l, l, , l, l, , Dicentric chromosomes (two centromere) are, common in maize., In polycentric chromosome the centromere lies in, the diffused condition along the length of, chromosome (eg. Ascaris)., The chromosomes whose centromeres are diffused, rather than discretely located, as they are in most, chromosomes, are called holocentric chromosome., Constriction present on chromosome other than, primary constriction is called secondary, constriction and the latter involved in the breaking, and fusion of chromosomes segments., In man secondary constriction II are found on the, long arms of chromosome 1, 10, 13, 16 and Y., Nucleolar organizer (called secondary, constrictions I) are necessary for the formation, of the nucleolus., The nucleolar organizer represents about 0.3% of, the total amount of nuclear DNA., Satellite are knob like part distal to nucleolar, organizer region., The chromosomes bearing satellites are called, SAT chromosome (due to pure stainability of, nucleolar organizer region). SAT stands for ‘Sine, Acid Thymonucleinico’ (without thymonucleic acid, or DNA)., The tips of chromosome are called telomeres., Telomeres have a unique property in that it prevents, the ends of the chromosome from sticking, together., Chromosome is 40% DNA, 50% histone,, 8.5% proteins and 1.5% RNA., Chromonema is DNA histone thread or chromatin, thread which form the bulk of chromosomes., Coiling in chromonema can be pleconemic, (interwining) or paranemic (simple folding)., Chromatin is composed mainly of coils of DNA, bound to basic proteins called histones., The basic form of chromatin packing is commonly, known as the 30 nm chromatin fibre., The fundamental packing unit of chromatin is called, as nucleosome., Woodcock (1973) showed that under the electron, microscope chromatin appears to have a ‘string of, beads’ (called nucleosomes) structure., Each nucleosome bead consists of a set of 8 histone, molecules., Chromomere is a small beadlike structure visible, , l, , l, l, , l, , l, l, l, l, , l, l, , l, , 501, , on a chromosome during prophase of meiosis and, mitosis, resulting from local coiling of a continuous, DNA thread., The portion of genomic DNA which is genetically, active (transcriptionally active) and pale staining, with G and C banding is known as euchromatin., Euchromatin is condensed during cell division, and is relatively rich in GC base pairs., Heterochromatin (discovered by His) is a type of, chromatin that is darkly staining, tightly packaged, or coiled throughout the cell cycle and is generally, genetically inactive., There are two types of heterochromatin namely, constitutive heterochromatin and facultative, heterochromatin., Constitutive heterochromatin is fixed and, irreversible in form and function., Chromosomes 1, 9, 16 and Y chromosomes, contain regions of constitutive heterochromatin., Facultative heterochromatin has the facility to, return to the normal euchromatic state., Facultative heterochromatin is reversible, its, heterochromatic state depending on the stage of, development or the cell type examined. It becomes, sex chromatin body or barr body in early, embryogenesis., The inactive X chromosome is made up of, facultative heterochromatin., Barr body (sex chromatin) is the densely staining, mass that represents an inactivated X chromosome, found in the nuclei of somatic cells of most female, mammals., Number of Barr bodies is one less than the total, X chromosomes, one in XX (normal females), two, in XXX sex complement, absent in normal human, males and one in males with Klinefelter’s, syndrome., , Sex chromosome, l, , l, l, l, , The chromosomes which carry genes for sex, determination are called sex chromosome,, heterosome or allosome., Chromosome other than allosome are called, autosome., Human beings have 22 pairs of autosome and one, pair of allosome., Sex chromosomes are those chromosome whose, presence or absence on particular form determine, the sex of the individual in unisexual or dioecious
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 502, , l, , l, l, , l, l, l, l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , animals. Eg. XX–XY, XX–XO etc., The two sex chromosome in an individual may be, morphologically similar (homomorphic XX) or, different (heteromorphic XY)., Individual having heteromorphic chromosome, form two types of gametes., TDF (Testis determining factor) and genes for, hypertrichosis are found on Y chromosomes hence, called holandric genes., X chromosome was discovered by Henking (1891)., Y chromosome was discovered by Stevens (1902)., A set of chromosome of an individual or species, is called karyotype., To study karyotype of man WBC are cultured in, aseptic condition., On the basis of length human chromosomes can, be divided into seven groups., The arrangement where the karyotype of man is arranged, in a series of decreasing length is called idiogram., Tijo and Levan (1956) made the karyotype of, human chromosomes., , Chromosomal staining, l, , l, , l, , l, , Chromosomes are stained with special flourescent, dyes that have differential affinity for different parts, of the chromosomes., Bands are segments of stained chromosomes that, appear lighter, darker or stained as compared to, adjacent parts., Chromosome banding was discovered by, Caspersson and others in 1970. With one particular, dye, the chromosomes show a particular unique, banding pattern, i.e., the banding pattern is constant, with a particular treatment., Banding technique of chromosome staining is, highly useful in knowing various types of, chromosomal aberrations or abnormalities like, additions, deletions and inversions., , l, , l, , l, , l, l, , l, , l, , l, , B chromosomes are heterochromatic, supernumerary chromosomes which are, smaller than normal and show slower, replication. In excess they result in loss of, vigour. In Tradescantia edwardsiana there, are 5 supernumerary chromosomes in, addition to the twelve somatic chromosomes., m chromosomes are minute but functional, chromosomes which are found in some, bryophytes and insects., L chromosomes (also called E, chromosomes) are found in germline cells, which are eliminated during formation of, somatic cells., , Chromosomes can be stained by Janus, green B and acetocarmine., Q Banding is observed when the chromosomes, are stained with quinacrine mustard. The regions, of chromosome rich in A+T get stained intensely, but G+C rich regions do not., G Banding is observed when the chromosomes, incubated in saline are stained with Giemsa or, treated with urea or detergents. These bands appear, in the regions having S–rich proteins., R Banding correspond to the regions on, chromosomes having proteins lacking sulphur, which become visible when chromosomes, incubated in a bugger at high temperature and, stained with Giemsa., C Banding is observed when chromosomes are, treated with strong alkali followed by warm saline, and then stained with Giemsa. It appears around, the centromeric regions., , Giant chromosomes, l, , Giant chromosomes are very large chromosomes, reported from few special types of cells., , Table : Karyotype or idiogram of man, I, II, III, IV, V, VI, VII, , Group, , Size, , Position of centromere, , Idiogram number, , (A), (B), (C), (D), (E), (F), (G), , Large, Large (medium large), Medium, Medium, Small (medium short), Smallest, Small, , Metacentric or submetacentric, Submetacentric, Submetacentric, Acrocentric, sat (subterminal), Metacentric or submetacentric, Metacentric, Metacentric, sat, , 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and X, 13, 14 and 15, 16, 17 and 18, 19 and 20, 21, 22 and Y (have not sat)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 503, , ◙ĚňĚř– ·– ►ĺŕŐŇŐřŐŇĚř–, l, , l, , l, l, l, l, l, l, l, , l, , l, , l, , l, , l, , Two main types of giant chromosomes are –, polytene chromosomes and lampbrush, chromosomes., A chromosome having many chromonemata lying, side by side is called a polytene chromosome, (P.C.)., Polytene chromosomes were first observed byBalbiani, (1881) in salivary gland of Chironomus tantans., The name polytene (polys many, lainiathreads), was given by Koller., They are quite common in salivary glands of insects, and so are called salivary chromosomes., They are formed by endomitosis of somatic pairing, and are in permanent prophase., The chromosomes can reach a length of 2000 µm, and contain 1000 to 16,000 DNA., They also occur in other organs of insects, antipodal, cells, endosperm cells and suspensor cells., All the polytene chromosomes remain attached to, one another at a common point called, chromocentre., Polytene chromosomes show puffs or balbiani, rings which develop lateral loops where DNA, becomes active and produce copies of RNA., Relationship between bands of polytene, chromosomes and genes was shown by, Painter (1933) and Bridges (1936)., Lampbrush chromosomes are diplotene bivalents, (occurs in pairs) held together by chiasmata. First, description was given by Flemming (1882) on, amphibian oocytes and a detailed study was made, by J.Ruckert (1892) on the oocytes of sharks., Lampbrush chromosome bears loops for rapid, transcription and production of yolk and, informosomes (mRNA + proteins). Hence they, occur in oocytes., Besides oocytes, lampbrush chromosomes have, been reported in spermatocytes and giant nucleus, of Acetabularia., , l, , l, l, , l, l, , l, l, , SEX DETERMINATION, l, l, l, , l, l, l, l, , Functions of chromosome, l, l, l, l, , Chromosomes contain genes. All the hereditary, information is located in the genes., Chromosomes control the synthesis of structural, proteins and thus help in cell division and cell growth., They control cellular differentiation., By directing the synthesis of particular enzymes,, chromosomes control cell metabolism., , Chromosomes can replicate themselves or produce, their carbon copies for passage to daughter cells, and next generation., SAT chromosomes produce nucleoli for synthesis, of ribosomes., Their haploid or diploid number respectively bring, about gametophytic and sporophytic characteristics, to the individual., Chromosomes forms a link between the offspring, and the parents., Some chromosomes called sex chromosomes (e.g.,, X and Y or X and O) determine the sex of the, individual., Through the process of crossing over, chromosomes, introduce variations., Mutations are produced due to change in gene, chemistry., , l, l, l, , Wilson and Stevens (1905) put forward the, chromosome theory of sex., Sex determined at the time of fertilization is known, as syngametic sex determination., Types of sex determination methods are –, –, XY method (mammals, some insects) , XX – , XY –, –, ZW method (birds, reptiles, fishes) , ZW – , ZZ –, –, XO method (roundworm, insects) , XX – , XO –, –, ZO method (moths, butterfly) , ZO – , ZZ –, The condition of sex determination in ZW method, is just opposite of XY method., In ZW method males are homozygous whereas in, XY method females are homozygous., XY determination is found in many bryophytes., Example of plants showing XY sex determination, method are Melandrium, Coccinia, Salix, Elodea, etc., Allen (1940) presented the list of plants where sex, chromosomes had been reported., Wastergard (1950) gave the list of plants where, heteromorphic sex chromosome were present., In Melandrium album diploids, triploids and, tetraploids have different doses of X & Y, chromosomes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 504, , l, , l, , l, , l, , l, , l, , l, , l, l, l, l, l, l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Sex of the baby depends upon the sperm (andro, or gyno) which fertilizes the ovum – boy if, fertilized with androsperm and girl if fertilized with, gynosperm. It depends upon chance which sperm, fertilizes the ovum., Twins are two babies given birth simultaneously, by a woman. If they develop from two separate, fertilized eggs, they are called dizygotic fraternal, twins. They may have the same or different sexes., Sometimes twins develop from the same fertilized, egg due to breaking after the first one or a few, cleavages. They are called monozgotic twins., Monozygotic twins are identical twins with same, genotype and sex. Breaking of young embryo often, results in monozygotic twins joined in various, regions. They are called siamese twins. It was, noticed by Warmeke (1946)., Plants are male when one or more, Y chromosomes are present and female when, Y chromosome is absent., Haplodiploidy is the sex determination method in, which one sex is haploid while other is diploid,, for eg. honeybees., Gynandromorphs are individuals where half the, body of male and half the body of female is found, in one individual., Gynandromorphs are of three types – bilateral,, anterioposterior and sex piebalds., In bilateral gynanders half lateral side is of male, and half is of female., In anterioposterior the anterior end of the animal, is of one sex and posterior half of other., In sex piebalds female fly bears irregularly scattered, spots of male tissue., Thomas Hunt Morgan (18661945) is called, Father of Experimental Genetics., Morgan discovered presence of gene over, chromosomes, chromosomal theory of linkage,, chromosome mapping, crossing over, criss cross, inheritance and mutability of genes., The organism selected by Morgan for his, experiments was Drosophila melanogaster., C.B. Bridges gave Genic balance theory for sex, determination in Drosophila. According to him X, chromosomes are carriers of genes for femaleness, and autosomes are carriers of genes for maleness,, so it is the ratio of number of X chromosomes, and autosomal sets, which determine sex., , l, l, l, , l, l, , l, l, l, , l, l, l, , l, , l, l, , l, , The first pair of Drosophila chromosome is that, of sex chromosome as they determine sex., The male fruitfly possesses XY sex chromosomes, while the female has XX chromosomes., Diagynic inheritance is the transfer of trait from, male parent to grandson through female offspring, and its vice versa is called diandric inheritance., A trait showing criss cross inheritance is sex linked., Criss cross inheritance is that type of inheritance, where the gene of one parent are transferred to, grand children through children of opposite sex., Criss cross inheritance establishes the relationship, between gene and the sex chromosomes., Non criss cross inheritance is both autosomal and, sex linked., Sex linked noncriss cross inheritance is holandric, (if it passes directly from father to son) and hologynic, (if it passes directly from mother to daughter)., The genes present on the differential region of Y, chromosome are called holandric genes., Holandric genes are passed directly from male, parent to male offspring., Failure of chromosome to separate during anaphase, is called nondisjunction which was first, discovered by Bridges (1916) in fruitfly., Meiotic nondisjunction is the non separation of, synapsed homologous chromosomes during, anaphase I of meiosis., Mitotic nondisjunction is the failure of daughter, chromosomes to separate during mitotic anaphase., Coupling occurs when two alleles coming from, same parent tend to enter same gamete and hence, transmitted together in an offspring., Repulsion occurs when two alleles coming from, different parent tend to enter different gametes to, remain apart in the offspring., , LINKAGE AND CROSSING OVER, l, l, , l, , Chromosome theory of linkage was put forward, by Morgan and Castle., According to chromosome theory of linkage, –, Genes show linkage, –, Genes lie linearly over the chromosome., –, Strength of the linkage is inversely, proportional to the distance between two, linked genes., Exception to Mendel’s study was proved by the, phenomenon of linkage.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚř– ·– ►ĺŕŐŇŐřŐŇĚř–, l, , l, l, l, l, l, , l, , l, l, l, , l, , l, , l, l, l, l, l, l, , l, , Linkage is the tendency for alleles of different, genes to be passed together from one generation to, the next., Gene located on different chromosomes cannot, show any linkage., Linked genes show dihybrid ratio of 3 : 1 and test, cross ratio 1 : 1., Linkage is of two types – complete and incomplete., Complete linkage is shown where no recombinant, type is formed., Incomplete linkage is the tendency of linked gene, to separate and form recombinant type due to, crossing over., Linkage group is a group of linearly arranged, linked gene which are inherited as a single unit due, to their being present on a chromosome., Number of linkage groups in a species corresponds, to its haploid number of chromosomes., Number of linkage group in pea, Drosophila, maize, and human are 7, 4, 10 and 23 respectively., Importance of linkage, –, The possibility of variation in gametes is, reduced by linkage (unless crossing over, occurs)., –, Linear arrangement of genes on, chromosomes., Traits which are determined by genes present on, sex chromosome are called sex linked traits, eg., haemophilia., Traits which are confined to express only in one, sex is sex limited traits, eg. milk secretion in, mammals., Traits found in a sex due to a particular sex hormone, are called sex influenced traits, eg. beard in man., Genes that lie far apart on the same chromosome, show 50% recombination., X chromosome of human has approximately 102, genes., Recombination frequency of 50% is the maximum, and gene that show this are called unlinked., Sir Archibald Garrod was the first who linked, alkaptonuria to a recessive Mendelian factor., In population genetics, the gene frequency can be, studied through Hardy – Weinberg law., p2 + 2pq + q2 = 1 (where p = dominant, q = recessive), Parental types are allelic combinations found in, the parents which are passed on to the gametes and, , l, , l, , l, , l, l, l, l, , l, l, l, l, l, l, , l, l, l, , l, , l, , 505, , offspring unaltered due to nonoccurrence of, crossing over., Recombinant types are new allelic combinations, different from those of parents due to crossing over, in their linkage groups., Crossing over is the cytological phenomenon, involving exchange of corresponding segments of, nonsister chromatids of a pair of homologous, chromosome by breaking and reunion following, synapsis., Mechanism of crossing over follows three process :, synapsis, duplication of chromosome and, chiasmata formation., Crossing over (C.O.) takes place at chiasmata., Jenssens (1909) was the first person to discover, chiasmata and related process of crossing over., Crossing over is observed in the pachytene stage, of meioticprophase I., The nonsister chromatids in which exchange of, segments takes place are known as crossovers or, recombinants., Linkage and crossing over are inversely, proportional., Crossing over and distance between genes are, directly proportional., The frequency of crossing over is an index of the, relative distance of gene on chromosome., Presence of heterochromatin decreases the, frequency of crossing over., Frequency of crossing over increases when exposed, to Xrays., Frequency of recombination is given as, = Total no. of recombination in test cross ´ 100, Total progeny in test cross, One crossing over produces 50% recombinant, type., Frequency of crossing over is double the, frequency of recombinants., Crossing over value is the frequency of crossing, over between two linked genes present on the same, chromosome., Crossing over map or chromosome map is a, graphical representation of relative position/order, and relative distances of genes in a chromosome in, a form of line., Morgan or map units are the units for crossing, over.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 506, , l, l, , l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , 1 map unit or Morgan is equivalent to, 1% recombination between 2 genes., The first organism where the linkage map for, various chromosome were constructed are, Drosophilia and maize., Recombinant frequency tends to be lower near, centromere and higher near telomere., Total number of recombination can be calculated, as 2n (n = no. of chromosome)., Factors influencing crossing over and linkage, are distance between genes, temperature fluctuation, (increased), X rays, age, sex, chemicals, interference, of cross over heterochromatin., Tetrad analysis is analysis of products of individual, meiosis so as to find out (i) linkage groups (parental, types) (ii) recombinations (recombinant types) (iii), segregation of genes and (iv) independent, assortment of genes., , GENETIC VARIATION, l, l, l, , l, l, l, , l, l, l, , Genetic variation arises due to two reasons–, recombination and mutation., Recombination is usually the most immediate, cause of variability., Recombination can occur in atleast three ways:, crossing over of chromosomes during meiosis;, random assortment of maternal and paternal, chromosomes during the production of egg and, sperm; and random combination of egg and sperm, at fertilization., Term mutation was coined by Hugo de Vries, (1901)., Bateson called mutation as discontinuous, variations or saltation., Mutation is the sudden stable transmissible, discontinuous variation which appear in an, organism due to permanent changes in their, genotype., De Vries observed 834 mutation in 54343 plants, of Oenothera lamarckiana., Mutation is of two types – induced mutation and, spontaneous mutation., Change in genotype occurred due to chromosomal, mutation (due to structural changes and changes, in number) and gene mutation., , l, , l, l, l, l, l, l, , l, l, , l, l, l, l, , l, , l, l, l, l, l, , Chromosomal mutation, l, , Chromosomal mutation is the changes that occur, in the morphology of chromosome resulting in, , l, , change in number or sequence of gene without, any change in ploidy., Chromosomal mutation due to structural changes, are of four types – deletion, duplication, inversion, and translocation., Deletion or deficiency involves the removal of a, section of chromosomes., Deletion are of two types – terminal and interstitial., In man deletion in chromosome 5 results in cri–, du–chat syndrome., In duplication, there is addition of a part of the, chromosome., Important examples of duplication is bar eye, character in Drosophila., The change in phenotypic expression when genes, are relocated without altering their number is called, position effect., In translocation a sequence of a chromosome, becomes attached to a nonhomologous chromosomes., In reciprocal translocation, mutual exchange of, segments between two nonhomologous, chromosomes occurs., Translocation in heterozygous condition are, reported in Oenothera, Rheo and Tradescantia., In inversion a section of the chromosome is, separated and reinserted after a rotation of 180°., Inversion can be pericentric (include centromere), or paracentric (beyond centromere)., Mutation caused by the variation in chromosome, number are of two types – euploidy and, aneuploidy., Euploidy is the condition in which chromosome, number is exact multiple of a genome, eg, monoploidy, diploidy, polyploidy etc., Gametes usually have one set of chromosome hence, haploid., The condition in which the chromosome sets are, present in multiple of n is called polyploidy., Polyploidy is of three types : autopolyploidy,, allopolyploidy, autoallopolyploidy., Autopolyploidy is the increase in the number of, the same genome, for eg. AAA., Allopolyploidy is the increase in number of, chromosome set due to coming together of genome, of two or more species, for eg. AABB., Autoallopolyploidy is the increase in chromosome, set due to coming together of different genome and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚř– ·– ►ĺŕŐŇŐřŐŇĚř, , l, , l, l, l, l, l, , l, l, l, l, l, l, l, l, l, , l, , occurrence of one genome in more than diploid, state, for eg. AAAABB., Aneuploidy is the phenomenon where change in, chromosome does not involve entire set of, chromosome but due to division or addition of, chromosomes., Hypoploidy is aneuploidy in which loss of, chromosome occurs., Hyperploidy is aneuploidy in which increase of, chromosome occurs., Trisomic and tetrasomic are types of hyperploidy., Monosomic, nullisomic are types of hypoploidy., Monosomic is 2n – 1, trisomic is 2n + 1, nullisomic, is 2n – 2, tetrasomic is 2n + 2, double monosomic, is 2n – 1 – 1, double trisomic is 2n + 1 + 1,, The example of monosomy in human is, Turner syndrome (44 + XO)., Trisomy of 21st chromosome results in, Down syndrome., Trisomy of 18th chromosome results in Edward's, syndrome., Trisomy of 13th chromosome results in, Patau's syndrome., 44 + XYY is called Jacob's or criminal syndrome., Klinefelter's syndrome is due to additional, X chromosome in normal male (44 + XXY)., 44 + XXX represents super female., All types of trisomic can be studied in Datura., Maximum number of chromosome is known for, Adder's tongue fern, Ophioglossum reticulum, (2n = 1262), and Aulocantha (2n = 1600)., Mixed aneuploids are aneuploids with both, hypoploidy and hyperploidy, e.g., 2N + 1 A– 1B., , Gene mutation, l, , l, l, l, l, l, , The sudden stable change in the structure of gene, or cistron due to change in nucleotide type or, nucleotide sequence is called spontaneous, mutation., Mutation which involve change in single nucleotide, is called point mutation., Point mutation is the process in which new alleles, of a gene are produced., Mutation from wild to new type is called forward, mutation., Mutation from mutated gene to its wild form is, called reverse or back mutation., Mutation which affects vegetative cells are called, , l, l, l, l, l, l, l, l, l, l, l, , l, , l, , l, l, l, , l, , l, l, , 507, , somatic mutation and those which affect sex cells, are called germinal mutation., Somatic mutation are not inheritable while, germinal mutation are inheritable., Recessive mutation show their effect after many, generation when they become homozygous., Pleiotropic mutation is the result of single mutation, changing more than one character., The gene mutation which involve more than one, base pairs or entire gene are called gross mutation., The smallest part of gene that can mutate is called, muton., The smallest muton in a gene is a single base pair, of DNA., Tautomerism is the phenomenon of changed, pairing qualities of the bases., Tautomerism is caused by chemical mutagens., Substitution gene mutation results when one or, more nitrogenous pairs are changed with others., Substitution (replacement) gene mutation is of two, types : transition and transversion., In transition mutation, a nitrogen base is replaced, by another of its type i.e., one purine is replaced, guanine) while one, by another purine (adenine, pyrimidine by another pyrimidine (cytosine, thymine or uracil)., In transversion, a purine base is substituted by a, pyrimidine base and vice versa, e.g., uracil or, thymine with adenine and cytosine with guanine., Frameshift mutations are those mutations in which, the reading of the frame of base sequence shifts, laterally either in the forward direction due to, addition of one or more nucleotides or in backward, direction due to deletion of one or more nucleotides., Two types of frameshift mutations are insertion, and deletion., In insertion one or more nucleotides are added in, the segment of DNA representing a cistron or gene., In deletion types of frame shift mutation one or, more nucleotides are lost from a segment of DNA, representing a cistron or gene., A gene or cistron of a protein will be having N, bases or nucleotides three times the number of, amino acids in a protein molecules., Genes which undergo mutations easily are called, mutator gene., Genes which does not undergo mutation even once, in several million gametes are called stable gene.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 508, , l, l, l, l, l, l, l, , l, l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Induced mutation was discovered by Muller, (1927)., Muller received Noble prize for his work in 1946., The experimenting organism used by him was, Drosophila and mutation was induced by X ray., Any physical or chemical agent which is used in, artificial induction of mutation is called mutagens., Physical mutagens are of three types – temperature,, UV radiations and ionising radiations., Increase in temperature increases the frequency of, mutations., UV radiations are non ionising radiations which, induce hydrolysis of cytosine and formation of, thymine dimers., Ionising radiation (X rays, cosmic rays etc.) distort, or break DNA duplex and disturb the replication., Chemical mutagens are chemicals inducing, mutations, for eg. nitrous acid, acridines,, 5 bromouracil etc., Nitrous acid (potent mutagen) deaminates cytosine, to uracil, guanine to xanthin and adenine to, hypoxanthin. This results in replacement of AT, with HC, CG with UA and CX., Alkylating agents bring about methylation and, ethylation of nitrogen bases, e.g., methyl guanine,, ethyl guanine. The alkylated base may slip out of, DNA duplex or cause change of base pair, e.g., C, G to AT., 5bromouracil (Bu), 5iodouracil (Iu), 5, chlorouracil (Cu) and 5fluorouracil (Fu) replace, thymine and pair with guanine. 2aminopurine is, incorporated in place of adenine with its tautomer, pairing with cytosine., Alkylating agents have been used in warfare as, the poisonous gases known as mustard gases; they, cause extremely painful death acting on skin,, mucosal membranes and lungs., Some common alkylating agents causing mutations, are:, –, Nitrogen mustard, –, Ethyl Methane Sulfonate (EMS), –, Methyl Methane Sulfonate (MMS), –, NmethylN’nitronitrosoguanidine (NTG)., Acridines like proflavin, acriflavin, euflavin and, acridine orange are intercalated in between base, pairs leading to their insertion and deletion so as, , l, l, , l, , l, l, , to cause frameshift or gibberish mutations., Most of the mutagens are also carcinogens., In some mutations, change in one nucleotide does, not result in the change of amino acid. Such, mutations are called same sense mutation or silent, mutation, for eg. AGA = AGG = AGT = AGC., Mis sense mutation is caused when a nucleotide, change in one codon causes the change of one amino, acid., Early termination of polypeptide chain due to certain, mutation is called non sense mutation., Non sense mutation is caused due to occurrence of, any of the three terminating codon viz, UAA,, UGA, UAG., , NUCLEAR AND CYTOPLASMIC, INHERITANCE, l, l, , l, l, l, l, l, l, l, l, l, , l, l, , l, , Inheritance is of two types : nuclear & cytoplasmic., In nuclear inheritance, traits are equally, contributed from both the parents towards the, inheritance of the offspring., In nuclear inheritance results of reciprocal crosses, are same., In cytoplasmic inheritance the result of reciprocal, cross is not same except sex linked cases., In cytoplasmic inheritance transmission of traits, takes place through cytoplasmic particles., Cytoplasmic particle constitute plasmones., Unit of plasmone is called plasmagene., Plasma genes are found in plastids, mitochondria,, plasmid and particles like alpha, beta, kappa etc., The plasmagenes are present inside cytoplasm in, random fashion., DNA is present in mitochondria and chloroplasts, too., In cytoplasmic inheritance offsprings bears the, character of female parent which contributes the, main part of egg cytoplasm., In cytoplasmic inheritance there is no segregation, at the time of meiosis., Cytoplasmic inheritance is observed in plastid, inheritance in Mirabilis and kappa particle in, Paramecium., Cytoplasmic inheritance of colour in plants was, first observed by Correns (1908) in Mirabilis, jalapa.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚŚĽĘ– ▐ďŚĚŕĽďń– ·– ▓ŕŐŚĚĽň– ☼ťňŚĺĚřĽř, , 509, , Chapter 54, , Genetic Material & Protein, Synthesis, GENETIC MATERIAL, l, , l, l, , Genetic material is that substance which not only, controls the formation and expression of traits, in an organism but can replicate and pass on, from a cell to its daughter cell or from one, generation to next., Earlier it was considered that proteins carry the, genetic information., DNA and RNA are two types of genetic materials., , l, , l, l, , DNA (Deoxyribonucleic acid), DNA as genetic material, l, The concept that DNA is the genetic material was, supported by the work of O.T.Avery and Coworker, (1944) and Hershey and Chase (1952)., l, The strongest evidence that DNA is the genetic, material comes from the studies on the bacterial, transformation., l, Pneumococcus experiment proved that DNA is the, genetic material., l, The transforming principle of Pneumococcus as, found out by Avery, MacLeod and McCarty was, DNA., l, The hereditary material present in the bacterium, E. coli is double stranded DNA., l, Fredrick Griffith, a British Medical Officer,, described the phenomenon of bacterial, transformation., l, Griffith experimented with the smooth (S) and, rough (R) strains of Diplococcus pneumoniae., l, Smooth (S) strains of bacteria were virulent or, pathogenic and cause pneumonia., l, Rough (R) strains of bacteria were non, pathogenic or avirulent., l, Both S and R strains are found in several types, , l, l, l, l, l, l, l, l, l, l, l, , l, , and are known as SI, SII, SIII etc. and RI,, RII, RIII etc. respectively., Mutations from smooth to rough strain occur, spontaneously with a frequency of about one cell, in 107 though the reverse is much less frequent., Transformation was the first step in the, identification of the genetic material., Transformation is the process by which a cell takes, up the segment of naked DNA from its, surroundings and incorporates it in its, hereditary material and ultimately expresses the, character specified by the incoming DNA., Griffith suggested that the cause of transformation, was the capsule of S strain., Hershey and Chase (1952) discovered that DNA, is the genetic material of bacteriophage., Bacteriophage are the viruses which infect bacteria., Hershey and Chase (1952) experimented with T2, phage which attacks the bacterium E. coli., T2 bacteriophage contains outer nongenetic, protein shell and inner core of DNA., The body of T2 phage is divided into head, neck,, and tail., Its head is elongated, six sided, bipyramidal and, contain non ending DNA molecule., The tail is a hollow cylinder bearing 24 helical, striations and is formed of proteins only., Six tail fibres appear from the hexagonal plate at, the distal end., Experiment of Hershey and Chase include the, process of transduction., Transduction is the process in which a bacterium, infecting virus serves as a vector transferring, DNA from one bacterium cell to another., The isotopes used by them were 35S and 32P.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 510, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Though DNA is the genetic material but, in some viruses like TMV, polio viruses, influenza, virus etc. RNA acts as genetic material., , Structure of DNA, l, DNA is the major store of genetic information as, the hereditary information is carried in DNA., l, DNA is found in nucleus and cytoplasm. The, contribution of cytoplasmic DNA in the cell’s total, DNA is about 1 5%., l, Extranuclear DNA is found in mitochondria and, chloroplasts., l, Rosalind Franklin, studied the structure of DNA, using Xrays. It showed that DNA is a helix., l, In 1953, James Watson and Francis Crick, proposed the threedimensional structure of DNA, based on Xray diffraction photographs of DNA, fibres taken by Rosalind Franklin and M.H.F., Wilkins., l, For discovering the structure of DNA, Nobel Prize, was awarded to Watson, Crick and Wilkins in the, year 1962., l, The Watson and Crick model shows that DNA, is a double helix with sugarphosphate backbones, on the outside and paired bases on the inside., l, The planes of the bases are perpendicular to the, helix axis. The planes of sugars are nearly at right, angles to those of the bases., l, The diameter of DNA molecule is 20 Å., l, The pitch (a complete turn) of DNA has a length, of about 34 Å., l, Adjacent bases are separated by 3.4 Å along the, helix axis and related by a rotation of 36 degrees., l, There are about 10 base pairs in each turn of DNA, double helix., l, The two chains are held together by hydrogen, bonds between pairs of bases which help to, stabilizes the interaction., l, Hydrogen bonds join the nitrogen bases of one, strand with of the other., l, Adenine thymine pair has 2 hydrogen bonds while, guaninecytosine pair has 3 hydrogen bonds., l, Adenine always pairs with thymine in DNA and, with uracil in RNA. Whereas cytosine always pairs, with guanine in both DNA and RNA., l, Linus Pauling believed that DNA has three strands., l, Each DNA strand has a backbone of alternate, , l, l, l, , l, , l, , l, , l, l, , l, , l, l, , l, l, l, l, , l, l, , deoxyribose and phosphoric acid groups., The polynucleotide chains in DNA molecule show, polarity in direction., One end of each chain is called 5¢ end and the other, is called 3¢ end., The sugarphosphatesugar component which are, joined by phosphodiester bond forms the backbone, of DNA duplex., The nitrogenous base molecules are attached with, the deoxyribose sugar molecules by glycosidic, bonds., The carbon atoms of the pentose sugar involved, in phosphodiester bond formation in DNA are, C3 and C5., The two strands of DNA (called DNA duplex) are, antiparallel and complementary i.e. one in 5¢ ®, 3¢ direction and the other 3¢ ® 5¢ direction., DNA is always double stranded, and rarely single, stranded., DNA duplex is made up of two molecules out of, which the one that directs the synthesis of the RNA, via complementary base pairing is called template, or sense strand and the other one is called antisense, strand., DNA molecule is composed of four kinds of, nucleotides (AMP, GMP, CMP, TMP) which differ, in relative amount from species to species., Behrem (1938) found the differentiation of DNA, from RNA., W.T.Astbury (1940s) found through X ray, diffraction study of DNA that it is a polynucleotide, with nucleotides lying at right angle to the long axis, of molecule., Kossel (1910) discovered the presence of two purine, and two pyrimidine in nucleic acid., Feulgen (1912) found staining reaction for DNA, which is now called feulgen reaction., Chemical studies on the bases of DNA were, performed by Erwin Chargaff in 1950., Pyrimidine bases of DNA are represented by, thymine and cytosine and purine bases by adenine, and guanine., Erwin Charagaff (1950) found that purine and, pyrimidine content of DNA are equal., According to Chargaff the, % of A = % T, percentage of adenine (A) is, % of G = % C, equal to the percentage of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚŚĽĘ– ▐ďŚĚŕĽďń– ·– ▓ŕŐŚĚĽň– ☼ťňŚĺĚřĽř, , l, , l, l, l, l, , thymine (T) and the percentage of guanine (G) is, equal to the percentage of cytosine (C)., The percentage of A + G equals 50% and the, percentage of T + C equals 50%. These, relationships are called ‘Chargaff’s rules’., A = C =1, Quantitatively A = T and C = G or, ., T G, Chargaff rule also states that A + G = T + C or A, + C = G + T., While the base ratio may vary from species to, species but it is constant for a given species., Base ratio is high in advanced organism and low in, primitive organism., , Types of DNA, l, Under different conditions of isolation, purification, and crystallization, several forms of DNA have been, recognised. They are A–, B–, C– D– and Z–DNA., l, A–, B–, C– and D–DNA are righthanded helices, whereas Z–DNA is lefthanded helix., l, Base pair turn in A, B, C, D and Z are 11, 10, 9, 8, and 12 respectively., l, Z DNA has zig zag sugar phosphate back., l, Z DNA was first reported by Rich and Coworker, (1979)., l, B DNA is the commonest DNA and are, metabolically stable., l, It is believed that during transcription the, BDNA changes to A form., l, B DNA exists under condition of high humidity, (> 92%) and concentration of salts., l, Under low humidity condition, the Bform may, change to A, C or D form., l, Another form of DNA has been also identified, which is designated as EDNA. The base pair in, one pitch is 7.5., l, DNA may be circular or linear depending upon, the absence or presence of free end., l, Linear DNA, having free ends, occurs in eukaryotic, nuclei, some prokaryotes like PPLO and some, autonomous cell organelles occasionally., l, Circular DNA, with no free end occurs in bacteria, and randomly in semiautonomous cell organelles, (like mitochondria and chloroplast)., l, Single stranded DNA was first observed by, Sinsheimer (1958), in the spherical bacteriophage,, f × 174., , l, , l, l, l, l, , 511, , The part of the genome in which repetitive sequence, are arranged end to end as long tandem arrays is, called satellite DNA., Satellite DNA was the first type to be identified in, the human genome., Repetitive DNA occurs in telomere, centromere and, ends of transposons., In Drosophila, about 25% and in human beings, about 30% DNA are repetitive., Palindromic DNA is a part of DNA in which the, base sequences of one strand is opposite to that of, the other strand when read from opposite directions., DNA regions that transcribe rRNA are often, palindromic. The true significance of palindromic, DNA is, however, not clear, although several, function have been suggested, like –, –, Short palindromes may function as, recognition sites of DNA for proteins which, also have a two fold rotational symmetry, e.g., lac repressor protein, CRP proteins and many, bacterial restriction enzymes., –, Also gives structural strength to the transcribed, RNA by hydrogen bonding in hairpin loops., –, Long palindromic DNA molecules from some, lower eukaryotes have been shown to contain, genes coding for ribosomal RNA., 3¢ – C – C – G – G – A – A – T – T – C –, C – G – G – 5¢, 5¢ – G – G – C – C – T – T – A – A – G –, G – C – C – 3¢., , Functions of DNA, l, DNA has two important functions – heterocatalytic, and autocatalytic., l, In heterocatalytic function, DNA directs the, synthesis of chemical molecules other than itself, e.g., synthesis of RNA, proteins etc., l, In autocatalytic function DNA directs the synthesis, of DNA itself., l, When the DNA is heated above physiological, temperature (about 100°C) the two helix unwind, and separate by breakdown of hydrogen bonds, between the base pairs. This is called denaturation, or melting., l, When the denatured DNA is cooled slowly, the two, strands reunite. This phenomenon is called, annealing.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 512, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , DNA, The Master Copy– DNA does not directly, control the formation of a polypeptide. Instead, it, forms an intermediate template, mRNA molecule,, which, in turn, directs the synthesis of the, polypeptide. The DNA is compared to a master copy, that is carefully preserved in the nucleus and used, only to prepare working copies in the form of mRNA, molecules. The latter pass out to the ribosomes in, the cytoplasm and guide the actual synthesis of, proteins., , Replication of DNA, l, Replication is the formation of exact replica or, carbon copy., l, According to Delbruck, there are three theoretical, possibilities for DNA replication viz. dispersive,, conservative and semiconservative., l, During dispersive method the DNA undergoes, fragmentation and then replicate and joins to form, two molecule of DNA., l, During conservative method the original DNA, molecule is conserved and its copy is synthesized, from the medium., l, According to semiconservative method the two, strands of the DNA separate and the complementary, strand is synthesized from the medium., l, Watson and Crick (1953) suggested that DNA, replication is semiconservative., l, Semiconservative replication of chromosome was, found by Taylor (1957) in Vicia faba using, triradiated thymidine., l, Messelson and Stahl (1958) proved that DNA, replicates by semiconservative method., l, They experimented on E.coli and use the heavy, isotopes of nitrogen i.e., N15., l, Messelson and Stahl grew bacterial DNA labelled, with 15 N in 14N medium and found that F 1, generation have DNA density intermediate, between the two., l, The newly synthesized DNA possess one strand, contributed by parent DNA and other newly, synthesized., l, The replication of DNA requires many enzymes, and protein factors., l, As the DNA in virus and bacteria are circular so, the replication in them ends at the same point, where it starts (Cairns 1953)., , l, l, l, l, , l, l, l, l, , l, l, l, l, l, l, l, l, l, l, l, , l, l, , l, , l, l, , The smallest unit of replication is called replicon., Bacterial DNA represents only one unit of, replication., Eukaryotic DNA are very large hence they, represent several replicon., During replication the four nucleotides of DNA, are activated by ATP in the presence of, phosphorylase., The first important step in the replication is, unwinding of double helix., The unwinding of DNA strand is done by enzyme, helicase., Helicase breaks the Hbonding present between, nucleotide pairs., The specific point from where the initiation of, unwinding starts is recognised by initiation, proteins., The existing DNA molecule on which new DNA is, synthesized is called as template DNA., The initiation of DNA synthesis requires a RNA, primer (a short sequence RNA)., The enzyme which forms RNA from DNA are called, RNA polymerase., The synthesis of RNA primer is brought about by, enzyme primase., The primer grows in 5¢ – 3¢ direction., In E.coli replication starts by the formation of, replication bubble., Topoisomerase acts as DNA nicking enzyme., Topoisomerase releases the tension of DNA strands., In prokaryotes, topoisomerase is replaced by DNA, gyrase., Initiation of replication occurs at 3¢ end., DNA polymerase is responsible for the template, directed condensation of deoxyribonucleotide, triphosphatase., DNA polymerase was discovered by, Kornberg (1957)., The enzyme DNA polymerase adds the nucleotide, complementary to the DNA template in 5¢ – 3¢, direction in the presence of ATP., The enzyme synthesizes a new strand in continuous, piece in 5¢ – 3¢ direction. This strand is called, leading strand., The second new strand is formed in short segments, called Okazaki fragments in 5¢ – 3¢ direction., Okazaki fragments are joined by means of DNA, ligase.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚŚĽĘ– ▐ďŚĚŕĽďń– ·– ▓ŕŐŚĚĽň– ☼ťňŚĺĚřĽř–, l, , l, , l, , l, , l, , l, , l, , l, , The strand formed by joining Okazaki fragments is, called lagging strand., DNA ligase was discovered by H.G. Khorana, (1967)., RNA primer is removed by exonuclease activity, of DNA polymerase I., The wrong base entered into DNA helix can be, identified and corrected by repair enzymes., The removal of wrong base is done by, DNA polymerase III, synthesis of new strand by, DNA polymerase I and sealing by DNA ligase., A Yshaped replication fork is formed during, DNA replication., DNA replication is semiconservative and semi, discontinuous., In vitro synthesis of DNA was first performed by, Kornberg (1959)., , l, l, , l, l, l, , l, l, l, , l, , RNA (Ribonucleic acid), l, , l, , l, , l, , RNA is a nonhereditary nucleic acid except in, some viruses (retroviruses)., RNA is a polymer of ribonucleotide and is made, up of pentose ribose sugar, phosphoric acid and, nitrogenous base (A, U, C, G)., Franklin Conrat (1957) establishes that RNA is, the genetic material is some viruses., RNA is single stranded, but double stranded RNA, is present in reovirus and wound tumor virus., , Types of RNA, l, The RNA may be mainly of two types – genetic, RNA and nongenetic RNA., l, Genetic RNA are seen in most of the plant viruses, and some animal viruses., l, The genetic RNA carries the genetic message and, is capable of self replication. It is called, RNA dependent RNA synthesis., l, On the basis of molecular size and function, three, main forms of non genetic RNA are – mRNA,, tRNA and rRNA., l, m RNA constitutes about 3.5% of cellular RNA;, t RNA is about 15% and r RNA about 80%., l, mRNA or messenger RNA are formed on specific, part of DNA as a complementary copy of one strand, of it in nucleus., l, mRNA forms a template for protein synthesis., , l, l, l, , l, , l, l, l, , l, , 513, , The life span of mRNA is short (2 min. in E.coli, & 4 hrs. in eukaryotes)., The length of mRNA is more than the length of the, protein synthesized., mRNA is called monocistronic when carries codon, for single complete protein molecule., Polycistronic mRNA contains several adjacent, DNA cistrons., tRNA or transfer RNA are also known as, soluble (s) RNA, supernatant RNA or adaptor, RNA., tRNA are smallest, bearing 7080 nucleotides., tRNA is single stranded and takes the shape of, clover leaf., The first person to determine the base sequence of, a tRNA molecule was Robert Holley., Holley (1965) reported the sequence of an alanine, tRNA from yeast and proposed twodimensional, structure of tRNA (clover leaf model)., Threedimensional structure of tRNA was, proposed by S.H. Kim in 1973., A threedimensional model of yeast phenylalanine, tRNA resembles an upsidedown letter L., Four sites can be recognised on tRNA. These are –, –, The site at 3¢ end is called amino acid, attachment site. It has base sequence CCA., –, Second site is called amino acid recognition, site or DHU loop., –, Third site is codon recognition site or, anticodon loop., –, Fourth site is ribosome recognition site or, GTPCG loop., tRNA helps to transport amino acids from the, surrounding cytoplasm to the site of protein, synthesis., The term ribosomal RNA (rRNA) has been, proposed by Kurland in 1960., Ribosomal RNA is found in ribosomes of cells and, is also called insoluble RNA., The main function of rRNA is to attract and, provide large surface for spreading of mRNA, over ribosomes during translocation process of, protein synthesis., In E. coli rRNAs are in three forms, sedimenting, at 23S, 16S, and 5S, respectively; these three forms, differ in base ratios and sequences.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 514, , l, , l, l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , In eukaryotic cells, which have larger ribosomes, than prokaryotes, there are four types of rRNA; 5S,, 7S, 18S, and 28S., rRNA or ribosomal RNA is formed from the, nucleolar organising region., Ribosomes are formed from rRNA and proteins., rRNA is involved in the translation of message, of DNA., rRNA forms the structural work bench on which, a polypeptide is formed, during protein synthesis., , GENETIC CODE, l, , l, l, l, l, , l, , l, l, l, l, l, l, l, , l, , l, l, , The genetic representation of codon by which the, information in RNA is decoded in a polypeptide, chain is called genetic code., The information is transferred in the form of triplet, of bases coding for one amino acid., George Gamow (1954) was first to propose triplet, code and coined the term genetic code., Triplet nature of genetic code was proposed by, F.H.C. Crick., Genetic code is the relationship of amino acid, sequence in a polypeptide and base sequence of, DNA., Marshell Nirenberg, Severo Ochoa, Hargobind, Khorana, Francis Crick, Matthaei deciphered the, genetic code., Nirenberg gave the first experimental proof for, triplet code., Nirenberg and Matthaei used artificially, synthesized m RNA in a cell free system., Three adjacent nitrogenous bases constitute a, codon and specify one amino acid., 61 out of 64 codons code for only 20 amino acid., Complementary matching input is called anticodon., There is no punctuation mark so that genetic code, is read continuously., The codon which initiates the protein synthesis is, called initiation codon. They are AUG for, methionine and GUG for valine., GUG when present in beginning codes for, methionine , but when present in intermediate, position, codes for valine., The codon which do not code for any amino acid, are called nonsense codon or terminator codon., Three codon viz. UAG (amber), UAA (ochre) and, UGA (opal) are non sense codon., , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , For a particular amino acid more than one codon, can be used. This is called degeneracy of codon., The first codon discovered by Nirenberg and, Matthaei was UUU (phenylalanine)., Khorana first deciphered the triplet codon of, cysteine and valine., Genetic code is universal., Genetic codes are non overlapping i.e., one letter, cannot be used for two different codons., A particular codon will always code for same amino, acid i.e., code is nonambiguous., With an exception GGA is an ambiguous code, it, codes for glycine and glutamic acid., Wobble hypothesis was given by F.H.C. Crick, (1965). According to this third nitrogenous base of, a codon is not much significant and codon is, specified by first two bases., Same tRNA can recognise more than one codons, differing only at third position., In Paramecium and some other ciliates termination, codons UAA and UGA code for glutamine., AGG and AGA code for arginine but function as, stop signals in human mitochondrion., UGA, a termination codon, corresponds to, tryptophan while AUA denotes methionine in, human mitochondria., The sequence of codon of DNA or mRNA, corresponds to the sequence of amino acids in a, polypeptide., A specific DNA segment will transcribe a specific, m RNA chain which will form a specific polypeptide, chain, this represents gene polypeptide parity., , CENTRAL DOGMA & PROTEIN, SYNTHESIS, , l, , Crick (1958) proposed the central dogma of, molecular biology., Central dogma is the unidirectional flow of, information from DNA to RNA and from RNA, to polypeptide., , l, , DNA ¾¾¾¾¾¾, ® mRNA ¾¾¾¾¾, ®, Polypeptide (Protein), Commoner (1968) suggested the circular flow of, information., H. Temin and Baltimore (1970) introduced the, , l, , Transcription, , l, , Translation
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚŚĽĘ– ▐ďŚĚŕĽďń– ·– ▓ŕŐŚĚĽň– ☼ťňŚĺĚřĽř, , l, , l, l, l, l, , l, , concept of reverse central dogma i.e., formation of, DNA from RNA., Reverse central dogma was performed by, retroviruses. This is represented as, RNA ® DNA ® m RNA ® protein., DNA is called the master copy and m RNA is called, the working copy of hereditary information., Proteins are the polypeptide chains formed by the, polymerization of amino acids., Only twenty amino acids are biologically important, in the participation of protein synthesis., The processes by which mRNA is made by DNA, and protein by mRNA are respectively called as, transcription and translation., One gene one polypeptide hypothesis states that a, structural gene specifies the synthesis of a single, polypeptide., , Transcription, l, , l, l, l, l, l, l, l, , l, l, l, l, , The process of transferring of information stored, in DNA to mRNA through the synthesis of RNA, over the template of DNA is called transcription., Transcription is the heterocatalytic function of, DNA., Transcription occurs during interphase., In prokaryotes single RNA polymerase enzyme, undertakes the formation of all RNA., In eukaryotes at least three RNA polymerase, enzyme (I, II, III) are required., RNA polymerase I is found in nucleolus and, forms rRNA., RNA polymerase II is found in nucleoplasm and, synthesise hnRNA., Heterogenous nuclear RNA (hnRNA), the, precursor of mRNA is synthesized by eukaryotic, cells, which undergo shortening by looping out, mechanism to remove unwanted nucleotide, sequence., RNA polymerase III is found in nucleoplasm and, synthesizes tRNA., One strand of DNA gives rise to mRNA. This strand, is called master strand or sense strand., The DNA strand which do not serve as template for, transcription is called antisense strand., The region where initiation began is called, promotor end while where transcription ends is, called terminator end., , l, l, l, l, , l, , l, l, l, l, l, l, , l, , l, l, l, l, , l, , 515, , RNA polymerase has five polypeptides – s, a, b,, b¢ and w., Chains of b, b¢, a and w constitute the core enzyme., The function of s factor is to confer the specificity, of RNA synthesis at the promotor site., s or sigma factor recognises the promotor region, while the remaining core enzymes takes part in, transcription., Rho factor which in course of transcription replaces, s factor helps in elongation and termination of, the RNA synthesis., The RNA molecule thus produced in transcription, is called transcript., After initiation base pairing takes place by, ribonucleoside triphosphates., Base sequence in DNA decides the base sequence, of RNA., mRNA synthesis on DNA template takes place in, 5¢ to 3¢ direction., The elongation requires the bivalent ion Mn++ or, Mg++., Primary transcript (newly formed RNA) is called, hnRNA as it is generally bigger than the functional, RNAs., Introns and intervening sequences of non essential, nature are removed by nuclease. This process is, called splicing., Ribozyme (RNA enzyme) is a self splicing intron, involved in splicing., Capping is the process of adding cap of, 7methylguanosine triphosphate at 5¢ end., mRNA cap is required for ribosomal recognition., Certain nucleotides are methylated, ethylated,, deaminated etc. to produce different chemicals like, inosine, methyl cytosine etc., In vitro synthesis of RNA was first performed by, Ochoa (1967)., , Translation (Protein synthesis), l, , l, l, , The process of decoding of the message from, mRNA to protein with the help of tRNA,, ribosome and enzyme is called translation, (protein synthesis)., Protein synthesis occurs over ribosomes. The, ribosomes are formed of two subunits., The rosette group formed by ribosomes is called, polyribosome.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 516, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , In polyribosome, ribosomes are held together by, strand of mRNA., The 4 main steps in protein synthesis (translation), are : activation, initiation, elongation and, termination of polypeptide chain., The newly synthesized mRNA joins the smaller, subunit of ribosome at 5¢ end., mRNAs carry the codon and tRNAs carry the, anticodon for the same codon., The amino acid bound to AMP is called amino acyl, ~ AMP or activated amino acid., Activation of amino acid is catalysed by the enzyme, amino acid synthetase in the presence of ATP., In presence of ATP an aminoacid combines with its, specific aminoacylt RNA synthetase to produce, aminoacyl adenylate enzyme complex., This reacts with tRNA to form aminoacyl tRNA, complex., Activated tRNA is taken to ribosome mRNA, complex for initiation of protein synthesis., Initiation of protein synthesis is accomplished with, the help of initiation factor which are 3 (IF2, IF3,, IF1) in prokaryotes and 9 in eukaryotes (eIF2,, eIF3, eIF1, eIF4A, eIF4B, eIF4C, eIF4D, eIF5,, eIF6)., A polypeptide chain forms as t RNAs deliver amino, acids to the ribosome., Large ribosomal subunit binds the initiation, complex forming two (A and P) binding site for, tRNA molecules., The first site is P site or peptidyl site which is, occupied by tRNAmet., The second site is A or amino acyl site and is, positioned over the second codon., The enzyme peptidyl synthetase catalyse the, formation of peptide bond between the carboxylic, group of amino acid at P site and amino group of, amino acid at A site., Enzyme translocase brings about the movement of, mRNA by one codon., After about 30 codons of mRNA get translated, a, new ribosome join at 5¢ end of mRNA to synthesize, another polypeptide., As many as 5 20 ribosome may join the same, mRNA depending upon its length., , l, , l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , The termination of protein synthesis occur when, a nonsense codon reaches at A site of ribosome., The chain detaches from the ribosome., Two subunits of ribosomes dissociate with the help, of dissociation factor., Termination requires the activities of three, termination factor R 1, R 2 & R 3., A potent inhibitor of protein synthesis that acts as, an analogue of aminoacyltRNA is puromycin (i.e., inhibit translation in eukaryotes)., In eukaryotes two types of polyribosomes are, found viz. free polyribosome, membrane bound, ribosomes., Free polyribosomes release their terminated protein, for direct function as enzyme in cytoplasm or in, the organelles such as chloroplast and mitochondria., Membrane bound ribosome attached to RER, wherein the synthesized proteins are translocated, through the lumen of ER., After synthesis the proteins may be incorporated in, membrane or may be secreted from the cell., Secretory proteins are synthesized by the ribosomes, attached to the endoplasmic reticulum membranes, and released into the ER. From here they are, transported to various membrane bound, compartments, e.g. the Golgi complex and the, lysosomes. They are then secreted from the cell by, exocytosis., Blobel’s and Dobberstein (1975) have proposed, the signal hypothesis for selective translation of, mRNAs., Signal hypothesis is the major mechanism whereby, proteins that insert into or cross a membrane are, synthesized by a membrane bound ribosome., The first thirteen to thirty six aminoacids synthe, sized, termed a signal peptide are recognized by, signal recognition particle that draws the ribosomes, to the membrane surface by interaction with a, docking protein. The signal peptide may later be, removed from the proteins., The hypothesis has been reviewed by Blobel (1978)., It is postulated that mRNAs translating secretory, proteins contain a group of signal codons on the 3¢, side of the initiation codon AUG. The ER membrane, is postulated to have ribosome receptor proteins, capable of moving in the plane of the membrane.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚŚĽĘ– ▐ďŚĚŕĽďń– ·– ▓ŕŐŚĚĽň– ☼ťňŚĺĚřĽř, , l, , Free ribosomes translate a polypeptide chain which, contains a signal peptide region. On emerging from, the ribosome the signal peptide interacts with the, ribosome receptor proteins forming a tunnel in the, membrane which coincides with the ribosomal, tunnel. An enzyme, signal peptidase, cleaves the, signal peptide from the growing polypeptide chain., When the chain is completed it is released into the, space of the ER. The ribosome detaches from the, ER membrane and the ribosome receptor proteins, diffuse in the plane of the membrane, closing the, tunnel., Blobel’s research has helped explain the molecular, mechanisms behind several genetic diseases., , l, , l, , Genetic control of proteins, l, , l, , l, , l, , l, , l, , The function of gene within an individual is in, ultimate sense, to control and influence the, phenotype., The characteristic of gene to store information and, contribute towards its expression in the form of, phenotype is studied by Garrod (1902). He studied, several disorders of human beings which seemed, to be inherited and called them as inborn errors of, metabolism., The evidence for inborn error of metabolism is, given by Beadle and Tatum (1948) in the, hypothesis “one geneone enzyme” which states, that “a gene controls a structural or functional trait, through controlling the synthesis of a specific, protein or enzyme formed by the gene”. According, to Beadle and Tatum gene is defined as a unit of, hereditary material that specifies a single enzyme., One gene one enzyme theory was given by Beadle, and Tatum (1958), while they were working on pink, bread mould or Neurospora (Ascomycetes fungus),, which is also called Drosophila of plant kingdom., Wild type Neurospora grows in a minimal medium, (containing surcose, some mineral salts and biotin)., The asexual spores, i.e. conidia were irradiated with, Xrays or UVrays (mutagenic agent) and these were, , l, , l, , l, , l, , l, , 517, , crossed with wild type., After crossing sexual fruiting body is produced, having asci and ascospores. Ascospores produced, are of 2 types –, –, The ascospores, which are able to grow on, minimal medium (like wild type), called, prototrophs., –, The ascospores which do not grow on minimal, medium, but grow on supplemented medium, (containing thiamine), called auxotrophs., Neurospora was used as material for genetic, experiments because –, –, It is haploid so every gene and every mutation, finds expression., –, Short life cycle., –, Few chromosomes, n = 7., –, Reproduces both asexually and sexually., –, It is heterothallic with two genetic strains,, A(+) and B(–)., –, Karyogamy and meiosis occur in the same, cell., –, The products are duplicated by mitosis and, changed to 8 ascospores., –, Products of meiosis remain linearly arranged., Shear and Dodge are known as Father of, Neurospora genetics as they discovered, Neurospora., Beadle and Tatum explained that thiamine synthesis, is completed in different steps and each steps is, associated with a specific enzyme, which in turn is, associated with a specific gene., In auxotrophs (mutated forms), due to mutation in, some genes (by XRays on UV rays) synthesis of, some enzymes is inhibited and hence synthesis of, thiamine is stopped., Thus auxotrophs are unable to grow on minimal, medium., One gene one enzyme theory is able to explain, some metabolic disorders or inborn errors in human, beings like – phenylketonuria and alkalptonuria.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 518, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 55, , Gene Expression &, Regulation, GENE EXPRESSION, l, , l, , l, , l, , l, , l, , l, , l, , l, , Gene expression is the mechanism at the molecular, level by which a gene is able to express itself in, the phenotype of an organism., The mechanism of gene expression involves, biochemical genetics., It consists of synthesis of specific RNAs,, polypeptides, structural proteins, proteinaceous, biochemicals or enzymes which control the, structure or functioning of specific traits., The formation of RNAs from gene is called, transcription., Out of the two strands of DNA, only one strand is, effective in producing mRNA in a given cistron. It, is called sense strand., mRNA carries the information to the ribosomes, and translates it into amino acid sequence of a, polypeptide with the help of tRNAs., The polypeptide expresses the gene by forming, a structural protein, a proteinaceous biochemical, or enzyme. This process is called translation., Gene expression begins with transcription and, translation and is followed by folding, post, translational modification and targeting., DNA, (cistron), , l, , l, , The amount of protein that a cell expresses depends, on the tissue, the developmental stage of the, organisms and the metabolic or physiologic state, of the cell., [For more detail on protein synthesis refer chapter, Genetic Material and Protein Synthesis], There is colinearly or similarity in the linear, arrangement of codons of a gene and the, sequence of amino acids in a polypeptide, produced by it., All the genes present on a chromosome are not, expressed simultaneously., , Gene expression in viruses, l, , l, l, l, l, , Virus is a nucleoprotein entity which lives as, intercellular obligate parasite because it is able to, utilise the synthetic machinery of host cell for its, multiplication., Virus is made up of two parts – capsid and, nucleoid., Capsid is a protein covering around nucleoid and, other parts., Virus has a linear or circular genetic material, (either DNA or RNA) and is known as nucleoid., TMV was the first virus to be discovered and, composed of entirely of protein and RNA., , mRNA, Ribosomes, (mRNAs), , Translation, , Polypeptide, , tRNAs, , Fig : Mechanism of gene expression, , Expression, , Structural, proteins, Proteinaceous, Biochemical, Enzyme
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚ– ◄ŤőŕĚřřĽŐň– ·– ☻ĚĹśńŐň–, l, l, , l, l, , l, , l, , l, l, , l, l, , l, l, l, l, l, l, l, , l, , TMV contain RNA as hereditary material., Virus undergoes two types of reproductive cycle –, lysogenic and lytic through which it multiplies, and thus expreses its genes., Virus reproduction is divisible into infection phase,, eclipse phase, maturation phase and lysis., Eclipse phase included replication of viral genome, and synthesis of viral proteins required for, inactivation of host cell genome & for initiating, regulation and control of viral synthesis assembly, and release., The time period between the infection of viral, nucleic acid and the first appearance of new phage, progeny is the eclipse period which is about 12, min. in T2phage., Multiplication of bacteriophage has been studied, in Teven phages of E.coli by prominent workers, like Delbruck, Luria and Lwoff., The complete virus particle prior of infection are, extracellular virions., Prophage or provirus is the latent stage of a phage, in a lysogenic bacterium in which the viral genome, becomes inserted into a specific portion of the host, chromosome and is duplicated in each cell, generation., Viral genome is changed to provirus/prophage state, by integrase enzyme., Phage having the capacity to become prophage is, called temperate phage and which lack this, property is called virulent phage., The multiplication process of virulent phage is, called lytic cycle., The multiplication process of temperate phage is, called lysogenic cycle., The phenomenon of existence of nonvirulent, prophage in the host cell is called lysogeny., The host cell in which lysogeny occurs is called, lysogenic cell., Lysogen is a strain of bacteria carrying prophage., Lysogenic cycle is shown by l (lambda) phage, which also infects E.coli bacterium., Lytic bacteriophage multiply in host bacterium, which then undergoes complete lysis (degeneration), to release the resulting daughter phages., Burst size is the number of virions produced per, host cell., , l, , l, , l, , 519, , Latent period is the total time taken from the, introduction of nucleic acid to rupture of host cell, wall. It is about 18 min. for T2 phage., The phenomenon of making DNA over RNA, genome through enzyme reverse transcriptase, is, called reverse transcription or teminism., Virus DNA is not affected by nucleases as its, cytosine bases are methylated (hydroxy methylated, cytosine or HMC)., [For more on virus refer chapter ‘Viruses’], , Gene expression in prokaryotes, l, , l, , l, l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, l, , Prokaryotes (mostly bacteria) have a genome that, consists of naked folded DNA (circular double, stranded) which does not contain any histone, protein but has polyamines, it is called nucleoid., Prokaryotic/bacterial cell’s nucleoid lies freely in, the cytoplasm & in contact with a membranous, structure called mesosome., Nucleus is absent in prokaryotic cell., Folding of DNA is done with the help of RNA and, polyamines., DNA is naked due to absence of histones in, prokaryotic chromosomes., The genome of E.coli contains 20003000 genes., Sexual reproduction is absent in bacteria as they, do not produce diploid phase which in turn leads, to absence of meiosis phase., Bacteria undergo replication of chromosome and, genetic recombination., Genetic recombination includes three processes as –, conjugation, transformation and transduction., In 1946, J. Lederberg and E.L.Tatum, demonstrated sexuality in bacteria for the first, time., Conjugation was observed under electron, microscope by Anderson (1957)., The unidirectional transfer of DNA from one cell, to another through a cytoplasmic bridge is called, conjugation., The process of conjugation is equivalent to sexual, mating in eukaryotes., Bacteria showing conjugation are dimorphic., Donor or male cell possess fertility factor (F+) and, sex pili (cilia like structure) while female or, recipient is without fertility factor & sex pili.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 520, , l, l, l, , l, , l, l, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Episome is the plasmid of fertility factor which is, integrated to bacterial chromosome., Episome was discovered by Jacob & Wollman., Contact between male donor and female recipient, causes development of conjugation tube by means, of a pilus of donor., Transformation is the transfer of gene for virulence, from DNA of dead bacteria to living non virulent, bacteria., It was discovered by Griffith (1928) in Diplococcus, pneumoniae., Ability to pick up foreign DNA for a brief period, towards the end of active growth is called, competence., Transduction is the transfer of genes from one, organism to another with the help of virus/vector., Transduction was discovered by Zinder &, Lederberg (1952) in case of Salmonella, typhimurium., Transduction is of two types – generalised (genes, are not fixed) & restricted (same genes, eg. lac or, biogene in case of lambda phage in Escherichia, coli K–12 because the phage genome attaches, between the two)., Plasmids are small double stranded circular, extrachromosomal DNA segments found in bacteria., [For more on bacteria refer chapter ‘Monera’], , Cancer and oncogenes (uncontrolled gene, expression), l, l, l, l, , l, l, l, l, l, , Cancer is uncontrolled growth of cells often, forming tumors and invading other tissues., Cancer is an example of growth lacking, differentiation and development., Tumor is a cellular lump., Tumor which remains restricted to the area of, formation is called benign/noncancerous/non, malignant., Cancerous/malignant tumors are abnormal group, of cells that may cause death of the individual., A malignant tumor of connective tissue is called, sarcoma., Metastasis is the secondary growth or invasions., Rous (1910) found a virus called Rous sarcoma, virus which causes cancer., In human beings cancer is caused by extra activation, of certain genes called protooncogenes., , l, l, l, , l, , l, , l, l, l, , l, l, , l, , l, l, , l, l, , A mutated protooncogene is called oncogene., Oncogenes were discovered by Bishop and Varmus., Mutation in protooncogene shatters the cellular, controls over the growth and division rendering, the concerned cells carcinogenic., Multiple genetic changes occur during the, transformation of a normal cell to cancer cell., This process is called oncogenesis., Oncogenesis is due to various factors as radiations,, heat, tobacco, continuous irritation, chemical, mutagens like tar, azo dyes, aromatic amines,, urathane, metals like nickel, beryllium, chromium,, arsenic., Any substances which causes cancer is called, carcinogen., Carcinolysis is the destruction of cancer cell., Due to presence of viral oncogenes in their, genome, retroviruses are implicated as a cause of, cancer in man., Jumping gene/transposon can also cause cancer., Translocation of fragment cabl from chromosome, 9 to chromosome 22 causes myelogenous, leukemia., Burkitt’s lymphoma is caused by translocation of, segment cmyc from 8 to 14 chromosomes., Tumor suppressor genes normally suppress the, tumor., Tumor appears only when the appropriate active, gene is absent or both the alleles are lost. It means, absence of tumor suppressor genes leads to, formation of tumors., In human beings cancer is caused by l , chromosome translocation., HIV (Human immunodeficiency virus) destroys, immune system of the body & cause AIDS., , GENE REGULATION, l, l, , l, , Different genes in an organism are meant for the, synthesis of different proteins., There are certain mechanisms that allow only the, desired genes to function at a time and restrict the, other., A variety of mechanisms are now known which, regulate gene expression at different levels, including transcription processing of mRNA and, translation.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚ– ◄ŤőŕĚřřĽŐň– ·– ☻ĚĹśńŐň–, l, l, , l, , l, , l, , l, , l, , l, l, l, , l, , l, l, , l, l, , l, , The regulation of gene expression (protein, synthesis) in bacteria is called operon system., Operon model was first given by two French, microbiologist Francis Jacob and Jacques Monod, (1961) in E. coli, for which they were awarded, Nobel Prize in 1965., Operons are segments of genetic material (DNA), which function as regulated units or units that, can be switched on or switched off., An operon consists of one to several structural, genes, operator gene, regulator gene, promoter, gene, a repressor and an inducer or corepressor, (from outside)., The segment of a DNA molecule determining the, amino acid sequence of a protein is known as, structural gene., Structural genes produce mRNA for forming, polypeptides/proteins/enzyme under the, operational control of an operator gene., Operator gene gives passage to RNA polymerase, (enzyme) moving from promoter to structural gene., i.e., it controls the activity of structural genes., Regulator gene controls activity of operator gene, by producing repressor molecules., The activity of the regulator gene is controlled by, a promoter gene on its left side., Promoter gene is an initiation point for, transcription and the site for binding of RNA, polymerase., The mechanism of regulation of protein synthesis, utilizing operon model can be illustrated using two, examples (lac & tryptophan) in bacteria., Operons are of two types – inducible and, repressible., A mutation taking place in a regulator gene may, produce a non functional repressor protein with a, changed amino acid sequence. Such mutants are, called constitutive mutants., A mutant repressor is not able to bind to the operator, gene and so RNA polymerase is not blocked., The structural genes that transcribe mRNA and, enzyme synthesis occur regardless of need and are, called as constitutive enzymes., A mutation in the promoter gene may totally prevent, attachment of RNA polymerase and there is no, transcription of mRNA and no enzyme synthesis, occurs., , l, , l, , l, , 521, , An uppromoter mutation results in an increased, rate of enzyme synthesis., A down promoter mutation decreases the rate of, RNA polymerase attachment and reduced enzyme, synthesis occurs., Model proposed to explain gene regulation in, eukaryotes are Frensters (1965) model of gene, specific derepressor RNA; models in which non, histone proteins act as derepressors, e.g., those, proposed by Paul and coworkers (1971) and Stein, et al, and Britten and Davidson’s operon operator, model (1969)., , Inducible operon system, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Inducible operon system regulate genetic material, which remains switched off normally but becomes, operational in the presence of inducer, e.g., Lac, operon system., Inducible operon system occurs in catabolic, pathway., Lac operon of E.coli has 3 structural gene – Z, Y, and A which produces 3 enzymes for the, degradation of lactose to glucose and galactose., Z produces bgalactosidase for splitting lactose, into glucose and galactose., Y produces bgalactoside permease (membrane, bound protein) which is required in entry of the, lactose/galactose., A produces bgalactoside transacetylase enzyme, that transfers an acetyl group from acetyl CoA to, bgalactosides., The initiation codon of structural gene Z is TAC, (corresponding to AUG of mRNA) and is located, 10 base pairs away from the end of the operator, gene., The substance whose addition induces the synthesis, of enzyme is called inducer., Inducer is a chemical which attaches to repressor, and changes the shape of operator binding site, so that repressor no more remains attached to, operator., In the lac operon allolactose is the actual inducer, while lactose is the apparent inducer., Inducers which induce enzyme synthesis without, getting metabolized are called gratuitous, inducers, e.g. IPTG (Isopropyl thiogalactoside).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 522, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , These type of inducers are very useful for, conducting recombinant DNA studies., Repressor is a small protein formed by regulator, gene which binds to operator gene and block, towards structural enzyme and thus checking mRNA, synthesis., It (repressor) has two allosteric sites, one for, attaching to operator gene & other for binding the, inducer., Repressor of lac operon has a molecular weight of, 160,000 and four subunits of 40,000 each., If lactose is added, the repressor is rendered, inactive so that it cannot attach on operator gene, and synthesis of mRNA takes place., Transcription is under negative control when lac, repressor is inactivated by inducer., Transcription in lac operon is under positive control, through cyclic AMP receptor protein (CAP)., The catabolite gene activator protein (Cga protein), or cyclic AMP receptor protein (CAP) binds to the, Cga site., When CAP is attached to the binding site the, promoter becomes a stronger one., CAP only attaches to the binding site when bound, with cAMP., When glucose level is high cAMP does not occur, and so CAP does not bind and hence RNA, polymerase do not bind , resulting in low, transcription., , Repressible operon system, l, , l, l, , l, , l, , Repressible operon system is that regulated genetic, material which normally remains active but can be, switched off when the cell does not require the, metabolite or the concentration of an end product, crosses a threshold value, e.g. tryptophan or try, operon system & arginine operon., It occurs in anabolic pathway., Tryptophan is an amino acids which is always, needed by the bacterial cell for protein synthesis, and hence produced by the sequential action of, enzymes., Tryptophan operon has 5 structural gene – E, D,, C, B, A., The gene E and D encodes for enzyme, anthranilate synthetase, gene E for glycerol, , 1., , 2., , 1., , 2., , l, , l, , l, l, , l, , l, l, l, , Regulation of enzyme synthesis by, induction and repression., I. Inducible system, Inducer absent : Regulator gene ® Active, repressor ® Binds to and blocks operator gene ®, No mRNA transcription by structural genes ® No, enzyme synthesis., Inducer present : Regulator gene ® Active, repressor ® + inducer ® Inactive repressor ®, No blocking of operator gene ® mRNA, transcription by structural genes ® enzyme, synthesis., II. Repressible system, Corepressor absent : Regulator gene ® Inactive, repressor (aporepressor) ® No blocking of, operator gene ® mRNA transcription by structural, genes ® Enzyme synthesis., Corepressor present : Regulator gene ® Inactive, repressor (aporepressor) ® + corepressor ®, Active repressor ® Binds to and blocks operator, gene ® No mRNA transcription by structural, genes ® No enzyme synthesis., phosphate synthetase and gene B for b subunit, of tryptophan synthetase and A for a subunit of, tryptophan synthetase., Operator gene of repressible operon is normally, kept switched on as aporepressor formed by, regulator gene is unable to block the gene., Aporepressor is a proteinaceous substance, formed by regulator gene of repressible operon, system., It is able to block operator gene only in the presence, of corepressor., Corepressor is a nonproteinaceous component, of repressor which is also an end product of, reaction catalysed by enzymes produced through, the activity of structural genes., It (corepressor) combines with aporepressor and, forms repressor which then block the operator gene, to switch off the operon., The structural genes stop transcription and the, phenomenon is known as feedback repression., Corepressor of tryptophan operon is, amino acid tryptophan., In tryptophan the repressor gene is not adjacent to, promoter but located in another part of E. coli, genome.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ĚňĚ– ◄ŤőŕĚřřĽŐň– ·– ☻ĚĹśńŐň–, l, , l, , l, , l, l, l, l, , In absence of tryptophan, the RNA polymerase, binds to the operator site and thus structural genes, are transcribed., The transcription of structural gene leads to the, production of enzyme (tryptophan synthetase) that, synthesizes tryptophan., When tryptophan becomes available, the, enzymes for synthesizing tryptophan are not needed,, corepressor (tryptophan) repressor complex, blocks transcription., One element of tryptophan operon is the leader, sequence ‘L’ that is immediately 5¢ end of trp. E gene., This ‘L’ sequence controls expression of the operon, through a process called attenuation., Attenuation is the termination of the transcription, permaturily at the leader region., The tryptophan operon is a negative control., , l, , l, , l, , l, l, l, l, , Importance of gene regulation, l, l, , l, , There are two types of gene action – constitutive, and regulated., The constitutive gene action occurs in those, systems which operate all the times and the cell, cannot live without them, e.g., glycolysis. It does, not require repression. Therefore, regulator and, operator genes are not associated with it., In regulated gene action all the genes required for, a multistep reaction can be switched on or off, simultaneously., , l, , l, l, l, , 523, , The genes are switched on or off in response to, particular chemicals whether required for, metabolism or are formed at the end of a metabolic, pathway., Gene regulation is required for growth, division, and differentiation of cells. It brings about, morphogenesis., During development from a zygote, multicellular, organism passes through a number of stages as, cleavage, determination, growth, differentiation, and development., Cleavage is early division of a zygote., Determination is the commitment of embryo cells, to develop into particular part of the organism., Growth involves cell division, cell enlargement etc., The process by which totipotent embryological cells, are converted into specialised cells constituting and, giving rise to specific tissue is called, differentiation, eg. RuBP in mesophyll cell and, bile in liver cell etc., Differentiation is accompanied by morphogenesis, and formation of different tissues and organs., Totipotent means capable of forming complete, organism (Driesch, 1892, 1900) by differentiation., Pluripotent means capable of changing but lacking, totipotency., Development is the whole series of events that occur, in the life history.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 524, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 56, , Human Genetics and its, Disorders, l, l, , l, , l, , l, , l, , l, , l, , Human genetics deal with the inheritance of, characters in man., Sir Francis Galton recommended two methods to, determine human genetics traits and their, inheritance. These methods are pedigree analysis, & studies of twins., Pedigree analysis is a graphical method, representing the generation of family with various, symbols used for relationships or for particular, chemical findings., Genes, the hereditary unit, contains the hereditary, information encoded in their chemical structure for, transmission from generation to generation., Any changes in the composition of one or more, genes on a chromosomes may produce structural,, physiological or biochemical abnormalities. Hence, these are called genetic disorders., Genetic disorders are also called congenital, diseases because these are present and existing from, the time of birth., Genetic disorders may be classified on the basis, of –, –, Chromosomal abnormalities, –, Incompatibility of genes, –, Single gene disorders., Chromosomal abnormalities may arises due to –, –, Non disjunction : When pair of chromosomes, fail to separate., –, Translocation : When a portion of, chromosomes breaks & attached to another., –, Deletion : When a piece of chromosomes may, detatch & lost from karyotype (chromosomal, complement of organisms)., –, Duplication : When some genes may appear, twice in the same chromosomes., , Inversion : When chromosomal segment, inverted & change or alter the order of, sequence of genes., –, Transverse division of chromosomes instead, of longitudinal division (iso chromosomes)., Disorders arises due to chromosomal abnormalities, may be either due to autosomal chromosomal, changes or sex chromosomal changes., Disorders of incompatibility of genes are of two, types – Rh factor incompatibility and ABO, incompatibillity., Caused by gene mutation, single gene disorders, (also called unifactorial diseases) are of three, types –, –, Recessive autosomal gene disorder (eg., sickle cell anaemia, alkaptonuria, albinism,, Tay sachs disease etc.), –, Defective dominant autosomal gene, disorder (eg. Huntington’s chorea,, achondroplasia etc.), –, Recessive sex linked gene disorder (eg., haemophilia, colourblindness, muscular, dystrophy etc.), –, , l, , l, , l, , CHROMOSOMAL DISORDERS, Autosomal chromosomal changes, l, l, , Due to changes in number autosomal disorders are, of two types – euploidy and aneuploidy., Euploidy is the numerical increase of chromosomes, from normal 2n to multiples of complete haploid, set i.e., 3X (triploid), 4X (tetraploid), 5X, (pentaploid), 6X (hexaploid). This is more common, in plants, rare in animals, and does not occur in, humans.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ◙ĚňĚŚĽĘř– ďňę– ĽŚř– ▼ĽřŐŕęĚŕř–, l, , l, , l, , l, , Aneuploidy relates to variation in chromosome, number with respect to one or only a few, chromosomes. The entire set is not involved in, aneuploidy. Thus, the person afflicted with this will, have one or few chromosomes more or less than, the diploid number., Aneuploids are of three types –, –, Monosomic (2n – 1), –, Nullisomic (2n – 2) when entire pair of, homologous chromosome from a diploid set, is missing, –, Polysomic when one or more chromosome, reduplicates., Polysomics can be of 4 types –, –, Trisomic (2n + 1) : having 3 chromosomes, (= copies) in one set instead of 2. This is due, to nondisjunction of homologous pair., –, Double trisomic (2n + 1 + 1) : 2 extra, chromosomes, –, Tetrasomics (2n + 2) : one chromosome in, quadriplicate., –, Pentasomics (2n + 3) : one chromosome in, pentaplicate., Disorders of autosomal chromosomal, abnormalities are Down’s syndrome, Edward’s, syndrome, Patau’s syndrome., , Down syndrome, l, Down’s syndrome occur due to trisomy of 21st, chromosomes with rounded face, flaccid muscle,, protruding tongue, folded eyelids short and broad, neck, feeble minded, low 1Q (20 50), severe, neurological disorders, prone to respiratory diseases, etc., l, This syndrome is also known as Mongoloid, syndrome., l, Survivers of Down’s syndrome have higher chances, of catching Leukemia and Alzheimer’s disease., Edward’s syndrome, l, Individual suffering from Edwards’ syndrome due, to trisomy of 18th chromosomes is characterized, by mental retardation, micrognathia short sternum, etc., Patau’s syndrome, l, Trisomy of 13th chromosomes results in Patau’s, syndrome., l, It is characterised by hare lip (a form of, congenital defect, sometimes hereditary, marked, , l, , 525, , abnormal clefts between the upper lip and the, base of nose), cleft palate (results from the, incomplete closure of palate or roof of the mouth, during early embryonic life), polydactyly etc., Death usually occurs soon after birth or may, survive upto 3 months., , Sex chromosomal changes, l, , l, , l, , l, , l, l, , l, l, l, , l, l, , l, , l, , The X and Y chromosome of humans differ in their, shape, size and banding patterns. X contains more, DNA than Y, also has more genes than Y. The, genetic capabilities of X are relatively higher than Y., Y is very much condensed & contains few, functional genes that determine male traits. They, are called holandric genes., Recessive alleles present on X have no equivalent/, comparable gene on Y. It is because of this reason, that recessive allelic genes of X easily express, themselves phenotypically., In females of all placentals including humans one, of the X chromosomes becomes inert by a process, called Lyonisation. This inert chromosome was first, discovered by Barr on the nuclear membrane as an, intensely stained body and is appropriately, designated as barr body., In genetically normal human female one barr body, is present. The male do not have it., Aneuploidy in sex chromosome results in increase, in the number of X (in some cases, Y as well) called trisomy., Trisomy arises by nondisjunction of homologous, chromosomes during egg cell formation., Nondisjunction is more common in sex, chromosomes than the autosome., Deletion of large part of the small arm of one of, the 5th chromosomes results in Cat cry syndrome, (discovered by Lejeune in 1963). These syndrome, is associated with malformation of the larynx., Child affected with cat cry syndrome during infancy, has a characteristic high pitched cry of kitten., Philadelphia chromosome is one of 22 autosomes, that has lost most of the distal part of its longer, arm., This chromosome is present in those individual, which are suffering from chronic myeloid, leukemia., It is characterised by an excess of granular
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 526, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , leucocytes in the blood which in turn reduces the, number of RBC resulting in severe anaemia., Hypertrichosis means excessive hair on ear pinna., Genes responsible for this are located on Y, chromosomes only which are also known as, holandric genes. This genes are not expressed in, females. Ylinked holandric genes are transmitted, directly from father to son., Genetic disorder due to sex chromosomal, numerical changes are – Klinefelter’s syndrome,, Turner’s syndrome, super males and super females., , Klinefelter’s syndrome, l, Klinefelter’s syndrome is one of the most common, cause of hypogonadism in the male., l, Klinefelter’s’ syndrome (XXY) is caused by, presence of extra Xchromosome due to union, of nondisjunct XX egg and a normal X and, abnormal XY sperms., l, These are genetically sterile male individual with, undeveloped testes, azospermia (less and deformed, sperm), gynaecomastia (enlarged breast), mental, retardation, occurrence of barr body etc., Turner’s syndrome, l, Turners’ syndrome (most common type of female, genetic disease) having XO genotype is caused, by the absence of X chromosomes in female., l, These are sterile females with poorly developed, ovaries and underdeveloped breasts. They have, webbed neck and broad chest., Supermales, l, Supermales (Y chromosome disorder) having XYY, genotype shows over production of testosterone,, unusual height, mental retardation, over, aggressiveness and criminal bent of mind., Superfemales, l, Superfemales, having XXX genotype, arises due, to presence of extranumerary chromosomes., l, These females are mentally retarded with congenital, abnormalities like underdeveloped external, genitalia, uterus and vagina., , INCOMPATIBILITY OF GENES, Rh factor incompatibility, l, , Rh factor was first of all reported in RBCs of, Macaca rhesus (rhesus monkey) by Landsteiner, and Wiener in 1940., , l, l, l, l, , l, l, , l, , l, l, , Rh factor is dominant character in heredity., The disease erythroblastosis foetalis in human, embryo is caused due to disadjustment of Rh factor., Erythroblastosis foetalis can occur when father is, Rh positive and mother is Rh negative., An Rh negative woman can be sensitized when she, bears an Rh+ child, and future Rh+ children may, have erythroblastosis foetails (also called, haemolytic disease of the newborn, HDN)., In developing foetus, erythroblastosis foetalis is, caused by haemolysis., Injection of antiRh (Rhogam) into an Rh negative, woman after the birth of each Rh positive baby can, prevent sensitization of the woman by binding Rh, positive blood cells from the baby., The commonest cause of haemolytic disease of, newborn is maternal alloimmunisation (immunity, arising from the mothers body itself)., No abnormality arises when mother is Rh (+)ve, and father is Rh(–)ve., Erythroblastosis foetalis occurs due to transplanted, transmission of maternally formed antibody, against the foetus erythrocytes, usually secondary, to an incompatibility between the mothers Rh blood, group and that of her offsprings., , ABO incompatibility, l, ABO incompatibility may lead to haemolytic, disease of new born, characterised with anaemia, and jaundice., l, ABO incompatibility is less severe as compared to, Rhincompatibility disorder. It occurs even in the, first baby., , SINGLE GENE DISORDERS, Recessive autosomal gene disorder, l, l, , Type of recessive autosomal gene disorders are, – phenylketonuria, albinism, alkaptonuria etc., Phenylketonuria, albinism and alkaptonuria etc are, caused by the absence of specific enzymes., , Phenylketonuria, l, Phenylketonuria occurs due to absence of, phenylalanie hydroxylase enzyme in liver which is, essential for the conversion of phenylalanine to, tyrosine., l, It is characterised by severe mental retardation,, hypopigmentation of skin and hair, eczema (itchy
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ŘśŇďň– ◙ĚňĚŚĽĘř– ďňę– ĽŚř– ▼ĽřŐŕęĚŕř, , skin), mousy odour of skin, hair and urine due to, increased phenylalanine in blood and urine., Alkaptonuria, l, Alkaptonuria is also called black urine disease., l, Alkaptonuria occurs due to absence of liver, enzyme, homogensate/alkapton oxidase which is, essential for the metabolism of homogentisic acid, (formed from phenylalanine and tyrosine)., l, It is characterised by the increased excretion of, alkapton and its accumulation in body produces, arthritis and other damages., Albinism, l, Albinism arises due to absence of enzyme, tyrosinase which catalyses the formation of, dihydroxyphenylalanine (DOPA) which form dark, brown pigment., l, During this eye disorders may occur due to damage, from bright light., Tay Sach’s disease, l, Tay Sach’s disease appears after birth due to, deficiency, of, enzyme, b DNacetyl, hexosaminidase., l, It is characterised with abnormal fat metabolism, leading to damage to brain and spinal cord resulting, in mental retardation and paralysis., Thalassemia, l, Thalassemia is a group of genetic disorders which, results from defective synthesis of subunits of, haemoglobin (a and b globin chains of, haemoglobin)., l, In athalassemia, out of four genes on 11th, chromosomes, absence of 2 genes leads to, microcytic and hypochromic erythrocytes without, significant anaemia. Death occurs in case of, deficiency of all the genes., l, bthalassemia is characterised by presence of two, defective bgene on 16th chromosomes., Sickle cell anaemia, l, Sickle cell anaemia is due to inheritance of a, defective allele coding for bglobin. It results in, the transformation of HbA into HbS in which, glutamic acid is replaced by valine at sixth, position in each of two bchains of haemoglobin., l, Sickle cell anaemia is a blood disease (affective, black Africans) where the red blood cells become, sickle shaped as compared to normal one., , l, l, , l, , l, , l, , l, , 527, , The sickle cells are rigid and exhibit a higher, viscosity to flow causing them to lodge in capillaries., The major characteristics of this disease are, anaemia and a tendency of the red blood cells, to change shape at low oxygen concentration., Due to insoluble in deoxygenated state sickle cell, haemoglobin precipitate in the red blood cells and, giving their characteristic bizzare shape., These cells are useless, so they have to broken, down and tend to jam in capillaries and small blood, vessels and prevent normal blood flow., The absent or reduced blood flow results in, ischemic damage to many different organs in, affected individuals., Sickle cell anaemia is an excellent example of, single mutation., , Galactosemia, l, Galactosemia in man is inherited as an autosomal, recessive, and the affected person is unable to, convert galactose to glucose., l, The disease is due to the deficiency of the enzyme, galactose phosphate uridyl transferase (GPT)., l, Untreated infants develop hepatomegaly, jaundice, and hypotonia and the symptoms can be relieved, if galactose is removed from the diet., l, The gene involved in the galactosemia is located, on the short arm of chromosome 9. Affected, individuals, who are homozygous for the allele,, exhibit enlargement of liver and spleen and some, mental retardation., , Defective dominant autosomal gene disorders, l, , l, , l, , l, l, l, , l, , Disorders due to dominant defective autosomal, genes are – Huntington’s chorea, achondroplasia,, polydactyly, bradydactyly, dwarfism., Huntington’s chorea (late acting dominant, disorder) is caused by a dominant gene mutation, on short arm of 4th chromosome., It is characterised by abnormal speech and, respiration, irregular arrhythmic movements of, limbs etc. due to atropy of brain parts., This disease does not appear till the age of 25 to 35., Achondroplasia is a hereditary disorder of, cartilage formation leading to dwarfism., Polydactyly and bradydactyly is a disease of more, than five digits in fingers and toes and a small, sized fingers respectively., Marfan syndrome is due to dominant mutation
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 528, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , resulting in the production of abnormal form of, connective tissues and characteristic extreme, looseness of joints. The long bones of body grow, longer, fingers are very long called ‘spider fingers’, or arachnodactyly; weakness develops in the, connective tissue and lenses in eyes become, displaced. The diagnosis is made on clinical, grounds, with involvement in at least two body, systems., The molecular basis of Marfan syndrome is, mutation of a structural gene (related to fibrillin, protein) on chromosome 15., Cystic fibrosis is most common diseases in North, America, rare in Asia including India. The body, produces abnormal glycoprotein which, interferes with salt metabolism. The sweat in body, becomes rich in sodium chloride; the mucous, secreted by body becomes abnormally viscid which, blocks passages in the lungs, liver and pancreas., Due to defective liver functioning the fat digestion, will not be normal. One of the principal organ, affected by cystic fibrosis is pancreas which, develops fibrous growth., The gene, responsible for this defect (cystic, fibrosis), has been localized to chromosome 7 and, it codes for a chloride transport factor (CFTR) and, multiple alleles., Gaucher’s disease is a genetic disease associated, with abnormal fat metabolism. It is caused by, the absence of the enzyme glucocerebrosidase, required for proper processing of lipids., , Recessive sex linked gene disorders, Disorders occurs due to recessive sex linked genes, are – haemophilia, redgreen colourblindness,, muscular dystrophy etc., Haemophilia, l, Haemophilia is also known as bleeder disease, (John Otto, 1803)., l, It is an popular example of sex linked inheritence, in human beings., l, It occurs due to deficiency of plasma, thromoboplastin (haemophilia, Christmas disease), or antihaemophilia globulin (haemophilia A), during which the exposed blood does not clot., l, Haemophilia appears only in human male which, l, , can be transferred to their grandson through his, carrier daughter (crisscross inheritance)., Homozygous condition is lethal., Red green colourblindness, l, Red green colourblindness is more common in, male than females (20 : 1) due to presence of only, one X chromosome., l, The sufferer are not able to distinguish between, red and green colour., l, Red green colour blindness is also called Daltonism, or proton defect., l, Colourblindness is of three types : protanopia, (red colour blindness), deuteranopia (green colour, blindness) & tritanopia (blue colour blindness.), l, Colourblindness show crisscross inheritance as, in haemophila., Muscular dystrophy, l, Muscular dystrophy occurs due to nonsynthesis, of protein, dystrophin which is required for, transfer of nerve impulse to calcium storing regions, of the muscle., l, Muscular dystrophy is of two types – Duchenne’s, pseudohypertrophy and Becker ’s/benign, pseudohypertrophic dystrophy (less severe)., l, It is characterised by deterioration of muscles at, an early age with progressive weakness of girdle, muscles, inability to walk after age of 12,, cardiomyopathy and mental impairment., G6PD deficiency syndrome, l, G6PD deficiency syndrome occurs due to, deficiency of glucose 6phosphate dehydrogenase, (essential for carrying out hexose monophosphate, shunt)., l, In the absence of G6PD, haemoglobin crystallizes, and erythrocyte membrane ruptures during, oxidant stress., Congenital night blindness, l, Congenital night blindness causes reduced, development of visual pigment (rhodopsin) that, interferes with the function of retinal rods and hence, night blindness. (Also occurs due to vitamin A, deficiency)., l, It is caused by a recessive gene carried by X, chromosomes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 529, , ▒ŕĹďňĽřŇř– ·– ◄ňŢĽŕŐňŇĚňŚ–, , Chapter 57, , Organisms & Environment, l, , l, l, l, , l, , l, l, , l, , l, l, l, , l, , l, , l, , Ecology (GK oikos home, logos study) is defined, as the study of interrelationships between living, organisms and their environment., The term ecology was coined by Ernst Haeckel., The two main branches of ecology are–, autoecology and synecology., Autoecology is the study of interrelationship of, the organisms of a species of biotic or abiotic, environment., Synecologyis the study of interrelationship of different, groups of the living organisms, such as populations,, biotic communities and ecosystems and their environment, which are associated together as a unit., Hierarchy means an arrangement into graded series., Ecological hierarchy involves the following, categories – organisms, population, species, biotic, community, ecosystem, biome, biosphere., The hierarchy in the levels of organisation connected, with ecological grouping of organisms is called, ecological hierarchy., Individual organism is the basic unit of ecological, hierarchy which is a distinct living entity., Population is a group of similar individuals in a, particular geographical area or space., A biotic community is any assemblage of, populations of different species like plants, animals,, bacteria etc. living in a prescribed area or physical, habitat and interact with one another., Ecosystem is defined as the segment of nature, consisting of biological community and its physical, environment both interacting and exchanging, materials., Landscape is a unit of land with natural boundary, having a mosaic of patches. These patches generally, represent different ecosystem., Biome is a major ecological community or complex, communities that extends over a large geographical, area characterised by a dominant type of vegetation., , Biosphere, Ecosystem, Community, Population, Living, , Organism (individual), Organ System, Organs, Tissues, Cells, Organelles, Compounds, , Nonliving, , Molecules, , Colloids, Crystals, , Atoms, , Mixtures, , Elementary Particles, (Electrons, Protons & Neutrons), , Fig : Ecological hierarchy, l, , l, , l, , Biosphere is the biologically inhabited part of earth, along with its physical environment consisting of, lower atmosphere, land and water bodies., Environment is the sum total of all biotic and, abiotic factors, substances, and conditions that, surround and potentially influence organisms, without becoming their constituent parts., The constituents of environment which directly, or indirectly influence the form and functioning
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 530, , l, , l, , l, l, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , of organisms in any specific way are known as, environmental factors., Climate is the characteristic pattern of weather, elements in an area over a period of time with regard, to temperature, rainfall, pressure, humidity, wind etc., Temperature and rainfall are the two most, important factors which determine the climate, of an area., Microclimate is the local variation of climate that, occurs in an area of limited size., Habitat is the specific locality delimited by a, combination of factors, physical features and, barriers where a community resides., The part of the habitat having a specific property e.g.,, tree canopy, forest floor etc. is called microhabitat., Ecological niche is a specific part of habitat, occupied by individuals of a species which is, circumscribed by its range of tolerance, type of food,, range of environment, microclimate, shelter etc., The place where the organism lives, is called its, habitat while the conditions and resources for its, life activities constitute the environment., The environment factors are divided into two, categories on the basis of their nature :, –, Abiotic or nonliving or physical factors, –, Biotic or living or biological factors, , ABIOTIC FACTORS, l, l, , l, l, l, l, , l, , l, , The abiotic or physical factors affect the structure,, behaviour and life history of organisms., The four types of abiotic factors are climatic (light,, air, temperature, humidity, precipitation), edaphic, (soil), topographic (earth surface), and fire., An organism, itself is a component of environment., Its growth and development, behaviour & life, history, all are influenced by the environment., Atmosphere is transparent gaseous envelope, around the earth which extends upto 1600 km., Atmosphere contains nitrogen (78.03%), oxygen, (20.99%), noble gas argon (0.94), carbon dioxide, (0.036%) and traces of other gases with water, vapours and dust particles present in the lower, region., Atmosphere is divided into 5 layers troposphere,, stratosphere, mesosphere, thermosphere and, exosphere., Troposphere extends 8 16 km from surface of, earth showing decrease of temperature with height, from 15°C to –57°C., , l, , l, l, l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , Troposphere contains more than 90 percent of gases, in the atmosphere and is the most important zone, of the atmosphere., Cloud formation, lightning, thundering, thunder, storm formation etc. take place in troposphere., Stratosphere extend from 8 16 to 30 50 km., Clouds, dust particles and air masses are absent., Ozone is formed in the stratosphere from oxygen, due to intense solar radiations, 3O2 ® 2O3. It is, called ozone layer or ozonosphere., Mesosphere is present between 50 100 km height., Temperature decreases from –2°C to –92°C. Gas, molecules become charged., Thermosphere lies between 100 500 km height., Temperature rises from –92°C to 1200°C. Ionised, layers occur in this zone which are collectively, called ionosphere., Exosphere is extremely rarefield part of atmosphere, between 500 1600 km., Lower part of atmosphere (called air), moves and, forms wind due to uneven heating and rotation, of earth which has a direct mechanical effect, and an indirect physiological effect., A number of organisms live in water bottom is, called benthic habitat while above bottom is the, pelagic habitat., Light intensity, light direction and light quality, control a number of processes of organisms as , photosynthesis,, growth,, movements,, photoperiodism, etc., The different zones of light in aquatic habitat, are –, – Littoral zone : Shallow coastal region,, producers occur throughout., – Limnetic zone : Open water zone, oxygen and, light decreases with depth., – Photic zone, : Light can penetrate., – Aphotic zone : Light does not penetrate., – Benthic zone : Bottom zone., Light has many effects on animals also, by affecting, their several types of activities like pigmentation,, reproduction, development, growth, locomotion,, migration etc., Daily responses of animals to light conditions, are known as circadian rhythm whereas annual, responses are known as circannual rhythms., Temperature or the degree of hotness/coldness of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 531, , ▒ŕĹďňĽřŇř– ·– ◄ňŢĽŕŐňŇĚňŚ, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, , a place influences the climatic conditions, soil, conditions, activities of organisms and growth, responses of plants because it influences the rate, of all physiological process., Difference in temperature of water at different, depths result in thermal stratification in deep, water bodies., During summer, temperature is higher in the surface, water, which is separated from the deeper water, mass by a thermocline (a zone of gradual change, in temperature)., A thermocline often creates two different layers, i.e., epilimnion (upper layer of water) and the, hypolimnion (lower layer of water) in a single, body of water., Variations in temperature affects animals which are, broadly classified into two groups as , homeothermic and poikilothermic., Homeothermic or warm blooded or endotherms, are those animals (e.g., birds and mammals) which are, able to maintain their body temperature at a constant, level irrespective of the environmental temperature., Poikilothermic or cold blooded or ectotherms, are those animals (e.g., reptiles, fishes, amphibians), in which the body temperature fluctuates with, changes in the environmental temperature., Water is an important component of protoplasm, being used as a general solvent, a reactant, a, metabolic byproduct and an essential material, for maintaining turgidity., Water is a resource, a condition and a habitat in, itself., 71% of earth is covered by water in the form of, oceans, ice caps, glaciers, lakes, etc. 97.5% of all, water is found in oceans., It is a source of cloud formation, precipitation as rain, or snow, atmospheric humidity and dew formation., A large number of organism have evolved in water., They are known as aquatic organisms. The aquatic, habitat may be freshwater, marine or estuary., Water cycle has 2 components – global (long) and, local (short), Local or short cycle consists of –, –, Evaporation of water from an area, –, Condensation of water vapour, –, Precipitation over the same area, , l, , l, , l, , l, , Global or long cycle involves movement of water, vapours in the from of clouds, rainfall over a large, area and movement of water from one area to, another., Soil is the upper weathered part of earth’s surface, having mineral particles (45%), water (25%), air, (25%), living organisms and humus (5%) which, can substain terrestrial plant life., Transportation of soil occurs by different agents, and is referred accordingly as – colluvial (through, gravity), alluvial (running water), eolian (wind),, glacial (by glacier)., The different soils groups are –, –, Red soil – Most famous. They are acidic, laterite soils which are deficient in lime,, magnesium, phosphorus and potassium but, rich in organic matter, iron and aluminium,, support tea coffee rubber, cardamon areca, nut and paddy., –, Black soil – Also called black cotton soils/, regurs with dark brown or black colour from, organic matter, clay/hydrated iron and, aluminium silicates and undifferentiated B , horizon., O1, O2, , A0, A00 Organic horizon, , A1, A2, , A Horizon, , A3, B1, B2, , B Horizon, , B3, , Mineral, horizon, , C, , C Horizon, , R, , Parent, underlying D Horizon, rock, , Fig. A generalized forest soil profile showing various zones., Soil profile : A0freshly fallen litter (partly decomposed)., A00 organic matter (fermentation level and humus level)., A 1 organic debris + mineral. A 2lig h t c o lo u r d u e to le a c h in g ., A 3may be present or absent. BHorizon i r o n a n d a l u m i n i u m, compounds. B 1transitional layer. B 2dark coloured, maximum amount, of leached material. B 3large chunk of parent rock material + leached, material. Cthick, large masses of weathered mineral material., DUnweathered parent rock material.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 532, , ŕďőĽę– ĐĽŐńŐĹť, , Alluvial soils – Most productive of Indian, soils, contributes to the largest share of, agricultural wealth of the country. Generally, deficient in N2 and humus., –, Terai/Babar soils – Mostly colluvial, drained, ones highly productive., Depending upon the various integrations of soil, particles [gravel (2.00 mm & more), coarse sand, (2.00 mm to 0.2 mm), fine sand (0.20 mm to 0.02, mm), silt (0.02 mm to 0.002 mm), clay (below, 0.002 mm)], soil can be grouped into various, types – sandy soil, clay soil, loam soil, clay loam, soil, sand loam soil and silt loam soil., Sandy soils mainly consist of sand particles. These, are loose, dry and poor in nutrients. The water, holding capacity of such soil is poor., Clay soils chiefly consist of clay particles that are, of colloidal dimensions and have high plasticity, and possess high water holding capacity., Clay particles have very small interspaces between, them so that neither water nor air can circulate, freely and on getting water become waterlogged, so they are not suitable for plant growth., Loam soils have sand, silt and clay particles in, –, , l, , l, , l, , l, , l, , Some important terms related to soil, Weathering – Breaking of rocks into finer, particles, Humification – Formation of humus. Essential, for starting biological activity, and nutritional cycle., Pedogenesis – The weathered mineral matter is, changed to soil, Illuviation, – Deposition in lower layer, Elluviation – Washing down or leaching, Humus, – It is partially decomposed and, partially synthesised dark, amorphous organic matter., Humus is formed from detritus or, litter (amimal refuse, plant derbis), through degradation into raw, humus (individual components, recognisable) and leaf mould, (amorphous and colloidal)., Humus helps in weathering of, rocks, forms soil crumbs for, increased aeration and hydration,, has growth promoting chemicals, and releases nutrients slowly., , l, l, l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , more or less equal proportions and are the most, suitable for plant growth., Sand loams are those soils in which sand particles, predominate., Clay loam soils have a predominance of clay, particles and are suitable for plant growth., Silt loam soils have predominance of silt and on, getting water, silt loam becomes waterlogged with, poor air circulation and are not suitable for plant, growth., On the basis of water retained by soil, water has, been classified as gravitational water, capillary, water and hygroscopic water., Gravitational water is the free water which due, to the action of gravity moves downwards into the, soil until it reaches the watertable. This water is, of little direct value to the plants., Capillary water fills the spaces between non, colloidal soil particles and forms films around them., This water is held by the capillary forces around, and between the particles and is of greatest, importance to plant., Hygroscopic water is the water that occurs in the, form of thin film on the soil particles. This water, is not available to the plants., Field capacity is the maximum amount of water, that the soil can hold after the gravitational water, has drained away., When the percentage of moisture that is left in the, soil at the time at which the plants will not recover, from wilting is termed as permanent wilting point, or wilting coefficient., Topographic factors (physical geography) change, different climatic conditions which in turn affect, the vegetation., The important topographic factors are altitude, (height above level), directions of mountains,, steepness of slope etc., Fire is an important ecological factor in temperate, forest and grassland regions, as well as in tropical, areas having dry seasons. It brings about burning, of vegetations., Fires are generally classified as –, –, Ground fires These fires are flameless, develop in such conditions where organic, matter accumulated for longer periods., –, Surface fires It sweeps over the ground surface
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▒ŕĹďňĽřŇř– ·– ◄ňŢĽŕŐňŇĚňŚ, , l, , l, , rapidly and their flames consume the litter, living, herbaceous vegetation and shrubs., –, Crown fires These are most destructive,, burning the forest canopy, surface debris and, bringing about vegetative destruction at large, scale., Fire has been used by humans for a number of, purposes –, –, Clearing vegetation for construction of, residential and industrial estates., –, Creation of farmlands and orchards., –, Growing pastures., –, Scaring away wild animals., –, Enhance hunting., –, Increase in visibility., –, Enmity., The effects of fire are –, –, Destruction of plant cover., –, Destruction of litter mass., –, Loss of nutrients through volatilisation, e.g.,, nitrogen, chlorine, sulphur and part of phosphorus., –, Destruction of habitat resulting in, disappearance of many plants and animals., –, Disruption of nutrient cycling., –, The burning of vegetation exposes the soil to, direct pounding by rain drops, solar radiations, and wind., –, It takes a lot of time for replantation of burnt, down forests., , BIOTIC FACTORS, l, , l, , l, , l, , l, , Biotic community is an association of a number of, interrelated populations belonging to different, species, in a common environment which can, survive in nature., Biotic factors include all organic factors that mostly, influence growth and reproduction, e.g., plants,, animals, microbes, interaction of animals., These biotic interactions are of two types – positive, interactions (when both the organisms or one, organism is benefitted) and negative interactions,, when both the organisms or one organism is harmed), [for interaction between species refer chapter, Population, Biotic community and Succession], Man is always most important biotic factor. He, changes the environment by his activities regularly,, eg., by excessive cutting of trees, fire, domestication, of plants and animals, by causing different types of, pollution etc., Homeostasis is the term generally applied to the, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , 533, , tendency for biological systems to resist change, and to remain in a state of equilibrium., A factor that limits growth, development,, reproduction or activity of an organism by its, deficiency or excess is called the limiting factors, and its impact on the optimum functioning of the, organisms are called limiting functions., According to Liebig’s law of Minimum (Liebig,, 1840), the growth and reproduction of plants and, hence productivity of soil is limited by an essential, nutrient that becomes deficient or critically, minimum in relation to its requirement., According to law of limiting factors (Blackman,, 1905) when a process is conditioned as to its rapidity, by a number of separate factors, the rate of the, process is limited by the pace of the slowest factor., According to Law of tolerance the abundance and, distribution of organisms is controlled by any of the, ecological factor below its critical minimum and, above its critical maximum. Critical minimum and, critical maximum values of an environmental factor, influencing organisms are called limits of tolerance., Acclimatization is the physiological changes in an, organism in response to a change in a particular, environmental factor., Plants and animals undergo special characteristic, changes in order to live and adjust under prevailing, environmental conditions which is called, adaptation., According to the various modes of adaptation,, plants are grouped as xerophytes, hydrophytes,, halophytes, heliophytes and sciophytes., Xerophytic plants grow in dry habitats where, rate of respiration is very high. They are of 4 types –, ephemerals, annuals or drought evaders,, succulents and nonsucculents., Plants growing in aquatic habitat are called, hydrophytes. They may be submerged,, suspended, free floating, rooted with floating, leaves and emergent., Hydrophytes have mucilage, poorly developed, roots, presence of aerenchyma, poorly developed, xylem and leaves showing heterophylly in some., Halophytes are plants growing in saline habitat, like coastal areas, mangroves, tidal marshes etc., Heliophytes are plants growing in bright light, having small thick leaves, shorter and thicker, internodes, sunken stomata and thick cuticle.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 534, , 1., , 2., , 3., , 4., , ŕďőĽę– ĐĽŐńŐĹť, , Table : Plant adaptations, Special characters, Types of adaptation, Root system is extensive, leaves pale green in, Heliophytes, colour with hairy growth, palisade parenchyma, well developed. More flowering and fruiting., Leaves large, bright coloured, palisade, Sciophytes, parenchyma less developed, more vegetative, growth than flowering., Plants of dry habitats, Xerophytes, Plants live only in rainy season, (i) Ephemerals, Plants live for a few months after rain, (ii) Annuals, (iii) Succulents/drought Fleshy organ for storage of water and mucilage;, phylloclades (photosynthetic and green stem),, resistants, cladodes (12 internode long stem show, crassulacian acid metabolism) are present., True xerophytes, smaller shoot system, extensive, (iv) Non succulents, root system, small, leathery leaves, possess, prickles and spines., Hydrophytes, (i) Submerged, (ii) Free floating, , Not rooted, remain completely under water, Not rooted in mud, float freely on the surface of, water, (iii) Rooted hydrophytes Root fixed in mud but leaves are floating on, with floating leaves water surface., (iv) Rooted submerged Rooted in mud and remain in water., , 5, , l, , l, , l, , l, , (v) Rooted emergent, , Root fixed in soil, stem exposed to air., , Halophytes, , Grow in saline habitat, have high osmotic, pressure, show some xerophytic characteristics, like succulents leaves, stem, etc., Show mangrove vegetations in marshy areas,, possess pneumatophores (breathing roots),, vivipary (germination of seeds on parent plant), , Sciophytes are plants growing in partial shade, showing soft, slender stem, large and thin leaves,, thin cuticle and surface stomata., Certain plants are adapted to grow in oligotropic, soils (poor in nutrients), e.g., tropical rain forests, have plants showing mycorrhizal roots., Animals adapt themselves for protection from, predators, feeding habit, camouflage, mating,, adjust to environmental stress conditions., Physiological and behavioural adaptation to, environmental variations and stress conditions occur, , l, l, , l, , Examples, .........., , .........., , .........., Euphorbia, Echinops, Solanum surattense, Opuntia, Asparagus, Euphoria, (fleshy stem), Aloe, Agave, (fleshy leaves), Nerium, Casuarina, Capparis,, Acacia, .........., Ceratophyllum, Eichhornia , Lemna, Wolffia, Azolla, Salvinia, Trapa, Nelumbo, Marsilea,, Nyphaea, Hydrilla, Vallisneria, Isoetes,, Potamogeton, Ranunculus, Typha, Cyperus,, Sagittaria, Artiplex, Spartina, Tamarix, Avicennia,, Aegiatilis,, Rhizophora, , in the form of migration, hibernation, aestivation,, camouflage, mimicry, echolocation, water, scarcity and prevention of freezing., Migration is a two way movement of an animal group, to other places for food, climate and other reasons., Camouflage is the ability to blend with the, surroundings to remain unnoticed for protection,, e.g., insects, reptiles., Mimicry is the resemblance of one species with, another in order to obtain advantage against, predation.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▒ŕĹďňĽřŇř– ·– ◄ňŢĽŕŐňŇĚňŚ–, l, , l, , l, , Mimicry may be batesian (defenseless, e.g., viceroy, butterfly mimics unpalatable toxic monarch, butterfly) and mullerian (resemblance to two, animal both unpalatable/ferocious to their mutual, benefit, e.g., monarch butterfly and queen butterfly)., Hibernation is the winter sleep of some animals to, survive against food scarcity and cold weather in which, several physiological changes occur like lowering of, body temperature and slowing of pulse rate., Aestivation is the state of inactivity occurring in, some animals during prolonged period of drought, , l, , l, , l, , 535, , or heat, e.g., lungfish., Echolocation (production of echoes) is the process, used by bats to know their path while flying at, night., Some animals adapt cold hardiness by developing, extra solute in the body fluids and special ice nucleating, proteins in the extra cellular spaces, eg., ice fish., Animals facing water scarcity develop thick coat to, minimize evaporation, make minimum, consumption of water or may not produce urine,e.g.,, camel, kangaroo.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 536, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 58, , Population, Biotic, Community & Succession, l, , l, l, , Biotic community is a grouping of different but, interacting population of different species which, live harmonious in a given locality, eg. pond, forest, community etc., Each member of biotic community is called species., It is represented by population., , l, , l, , POPULATION, l, , l, , l, l, , l, , l, , l, , l, , Population is a group of individuals of the same, species within a community occupying a particular, space, has various characteristics which are unique, possession of the group., Population ecology is the study of all aspects of, a population and the various factors affecting it in, its growth, density, size, multiplication, natality,, mortality, competition etc., Population density is the number of individuals, of a species per unit area or space at a given time., The inherent ability of a population to increase is termed, natality. In broader sense natality is the production of, new individuals of any organisms per unit of population, per unit time through hatching, birth, germination or, vegetative propagation., Mortality is the rate of death of individuals per, unit time i.e., number of individuals dying in a, given period of time., Population dispersal is the movement of, individuals or their reproductive products into and, out of population area., Population dispersal takes place in three forms :, emigration (one way outward movement),, immigration (one way inward movement) and, migration (periodic departure and return)., The number of individuals added per unit, population per unit time due to higher rate of births, and immigrations over the rate of deaths and, , l, l, l, l, , l, , l, , l, , emigration is called population growth., Population have characteristic patterns of increase, called population growth forms which are, differentiated into two types J shaped growth, form and Sshaped growth form., The Jshaped curve is a biopotential curve when, environmental resistance is zero; it is produced, because larger populations increase more rapidly, than smaller ones., The Jshaped curve shows three stages: lag phase,, exponential phase and crash phase., In lag phase there is a slow rise in population as, the initial size of the population is very small., During exponential phase, the population size rises, rapidly., A point is reached when population declines, suddenly due to mass scale deaths. It is called, crash phase., The J type of growth pattern can be easily observed, in algal blooms, some insects, annual plants and, the lemmings of Tundra., The Sshaped curve (sigmoid curve) is generated, when a population approaches the environment’s, carrying capacity., The Sshaped curve shows three phases –, –, Early phase (Lag phase): Little or no growth, takes place due to small size of population, and lack of adaptation;, –, Middle phase (Log phase or exponential, phase): There is geometrical increase in, population size owing to abundance of food, and other favourable conditions., –, Stationary phase (Zero growth or Plateau, rate): Birth and death rates are equal, the, population stabilizes around the carrying, capacity of the environment.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐőśńŐňΘ– ▲ĽŐŚĽĘ– ►ŐŇŇśňĽŚť– ·– ☼śĘĘĚřřĽŐň–, , 537, , Table : Differences between Jshaped and Sshaped growth forms of population., 1., 2., 3., 4., 5., 6., 7., , l, , l, , l, , l, , l, , l, , l, , l, , Jshaped population growth form, , Sshaped population growth form, , It occurs in erruptive type of population, An equilibrium is never reach in population, size, Exponential phase is very rapid, A phase of deceleration never occurs, , It is found in stable type of population, An equilibrium is reached when the size of population, approaches the carrying capacity of the area., Exponential phase is comparatively less rapid, A phase of deceleration occurs before equilibrium is, reached., Environmental resistance begins to operate in slow down, exponential phase., Population seldom grows beyond the carrying capacity, of the area., A crash phase does not occur., , Environmental resistance does not operate, to slow down exponential phase, Population grows well beyond the carrying, capacity of the area, A crash phase occurs at the end of Jshaped, growth., Sshaped growth curve is seen more frequently as, in yeast cells grown in laboratory and human, population., The carrying capacity of habitat/locality/, environment is the maximum number of, individuals of a population that can be supported, in a given time., The number or percentage of the individuals in a, population in different age groups is called age, distribution., In ecology three different type of age groups have, been recognized, these are – prereproductive,, reproductive and postreproductive., The age distribution in a population may be, graphically represented in the form of an age, pyramid showing the number of individuals in, different age groups., Age pyramids are of three types. These are –, –, Triangular The number of prereproductive, individuals is very large., –, Bellshaped – The number of prereproductive, and reproductive individuals is almost equal., –, Urn shaped – The number of reproductive, age group is higher than individuals of pre, reproductive age group., Biotic potential (r) of a population is the potential, ability or inherent power of a population to increase, in the number when the age disribution in the, population is stable and all environmental, conditions are optimum., The sum of environmental factors that limits the, population size and keeps check on the realization, , l, , of full biotic potential is called environmental, resistance., Environmental resistance rises with the size in, population size., , BIOTIC COMMUNITY, l, , l, , l, , l, , Members of biotic community depends upon one, another for food, reproduction, dispersal and, productions, the phenomenon is called species, interdependence / interaction., Three types of interactions occurs amongst, different members of a biotic community neutral,, (no one is harmed neither benefitted), positive, (beneficial) and negative (antagonistic)., The relationship between two living individuals of, different species in which one is benefitted while, the other is neither harmed nor benefitted is, commensalism., Examples of commensalisms are –, –, The colonial hydrozoan Hydractina attaches, itself to whelk shells inhabited by hermit, crab., –, The woody stem of lianas is closely associated, with supporting tree., –, Orchids, bromeliads, Usnea, Alectoria, (epiphytes) grow on another plant for shelter, only but are nutritionally independent. The, large plant is neither benefitted nor harmed, by the growth of epiphytes., –, Some plants grow on the surface of animals, (epizoans). Basicladia grows on the back of, fresh water turtle.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 538, , ŕďőĽę– ĐĽŐńŐĹť, , –, , The pilot fish (Remora) always accompanies, shark., –, Sucker fish (Echeneis) attaches itself to under, surface of shark., Some animals are called ectocommensals or, epizoite. They are associated with other animal for, anchorage and protection. Examples are, Kerona, on Hydra, annelids on cray fish, barnacles which, attach themselves to the backs of whales., Commensalism may also be internal such as, Escherichia coli found in human colon., Mutualism is the interaction in which growth and, survival of both populations is benefitted and, neither can survive under natural conditions without, the other., Mutualism is also termed as symbiosis and is, generally obligatory., Examples of mutualisms are –, –, The sea anemone Calliactis attaches itself to, a shell used by hermit crab., –, Herbivorous ruminants contain a vast number, of cellulose digesting bacteria and ciliates., –, Formation of root nodule of leguminous plants, by Rhizobium, a bacterium., –, Anabaena (a nitrogen fixing blue green alga), is associated with water fern Azolla., –, Mycorrhiza is a mutualistic interaction in, which a fungus (e.g. Boletus) and a root (e.g., Pinus) are involved., –, Termites harbour cellulose digesting, flagellates in their alimentary canal., , l, , l, l, , l, l, , –, –, , l, , l, , l, , Swollen thorn of acacias give shelter to ants., The body of lichen is made up of a matrix, formed by a fungus, within the cells of which, an alga is embedded., –, Some unicellular photosynthetic plants, known, as zoochlorellae, live symbiotically in the, outer tissue of certain sponges and, coelenterates. Chlorella vulgaris lives within, the gastrodermal cells of Hydra., Protocooperation is nonobligatory mutually, beneficial relationship in which both the, populations benefit, e.g., crocodile bird rids, crocodile of leeches sticking inside its mouth., Amensalism is an interaction between two living, organisms in which one population is inhibited, (not allowed to grow) and the other is not, affected. E.g., penicillin does not allow, Staphylococcus bacterium to grow and Trichoderma, inhabits the growth of fungus Aspergillus and, Convolvulus arvensis inhibits the germination and, growth of wheat., Amensalism is of two types –, –, Antibiosis – Some microorganisms secrete, certain chemical substances which kill or, inhibit other microorganisms. These, substances are called antibiotics and, phenomenon is called antibiosis., –, Allelopathy – Some higher plants also secrete, certain chemical substances which inhibit the, growth of other plants. This phenomenon is, called allelopathy, eg, roots of carrot grass or, , Table : Interaction of species., Interaction, I., II., , III., , Neutral Interactions, Negative Interactions, 1. Competition, 2. Predation, 3. Parasitism, 4. Amensalim, Positive Interactions, 5. Scavenging, 6. Commensalism, 7. Protocooperation, 8. Mutualism, , Effect on, Species I, , Effect on, Species II, , Result, , Zero, , Zero, , Neither benefitted nor harmed, , (–), (+), (+), (–), , (–), (–), (–), Zero, , Mutual inhibition, One is benefitted, other is harmed., Parasite benefitted, host harmed, One harmed, other uneffected, , (+), (+), (+), (+), , Zero, Zero, (+), (+), , Useful to scavenger, no effect on other, Commensal benefitted, no effect on other, Both benefitted but association not obligatory, Both benefitted, association obligatory.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐőśńŐňΘ– ▲ĽŐŚĽĘ– ►ŐŇŇśňĽŚť– ·– ☼śĘĘĚřřĽŐň, , Ectoparasite, Endoparasite, Partial/temporary parasite, Permanent parasite, Holoparasite, Hemiparasite / semiparasite, , :, :, :, :, :, :, , Stem parasite, Root parasite, Pathogenic parasite, , :, :, :, , Nonpathogenic parasite, Hyperparasite, , :, :, , l, , l, , l, , l, , l, , The different types of parasites, live on the body of the host (e.g., sucking lice), live inside the host body (e.g., Ascaris, malarial parasite), spend only a part of their life cycle on the host (e.g., leech, female mosquito), spend their entire life as parasite (e.g., Ascaris, lice), completely dependent on their host for all requirement (e.g., Rafflesia), obtain a part of their nourishment from host and the rest is prepared by them own, (e.g., Viscum, Loranthus), live on the host stem to obtain food (e.g., Cuscuta, Loranthus), parasitic on host root (e.g., Rafflesia), parasite causes diseases in the host (e.g., Corynebacterium diptheriae causes, diptheria), parasite do not harm the host (e.g., Entamoeba coli), parasite that lives on another parasite (e.g., Nosema notabilis is the hyperparasite, on myxosporidian), , congress grass (Parthenium argentatum) which, is most troublesome terrestrial weed in India, secrete trans – cinnamic acid which checks the, growth of other plants., Competition is the relationship in which each, population adversely affects the other in the, struggle for resources in short supply., Competition is of two types as intraspecific, (between individuals of same species) and, interspecific (between individuals of different, species)., Predation is an interaction between members in, which one population adversely affects the other, by direct attack (capture, kill and eat) but is, nevertheless dependent on the other. The former is, called predators and the latter is called prey., The carnivorous animals eat the other animals and, the herbivorous animals eat the plants and so are, predators., Parasitism is the relationsip between two living, organisms in which one organism resides on the, body of the other living organism (host) and, derives nourishment from its tissues. It is always, an one side relationship for the parasite which is, always benefitted from the host., , l, l, , l, , l, , l, , l, , l, , l, , l, , The number of species of plants, animals and other, organisms that occur in a biotic community is called, species composition., Species composition (type of species) differs from, one ecosystem to another depending upon, geography, topography and climate., Maximum species composition occurs in tropical, , rain forests and coral reef and minimum occurs in, deserts and arctic regions., The total number of species and their relative, abundance in a biotic community is species diversity., Keystone species is a species which has, significantly large influence on the community, structure and characteristics., Removal and decrease in the number of key stone, species ca uses serious disruption in the, community., Critical link species are species which play an, imporant role in supporting network species by, functioning as pollinators, nutrient circulators, or absorbers., Ecotone is defined as the place or area, where two, major communities meet & blend together. It, consists of species of both the communities., The tendency of ecotone to contain a greater number, of species and a higher population density is called, edge effect., The species which are found most abundantly in, ecotone boundary are known as edge species., , Analysis of plant community, l, , Biotic community organization, l, , 539, , l, , Communities are analysed for –, –, Knowing the constituent species., –, Relative abundance, cover and importance of, species., –, Study of variations within and between, communities., –, Recording of various types of communities., –, Naming and classifying communities., Community characteristics are of two types–, analytical characters and synthetic characters.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 540, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Analytical characters are structural characteristics, which can be directly observed or measured., Analytical characteristics, if measurable, are called, quantitative characters, eg frequency, abundance,, diversity, biomass, leaf size., Non–measurable analytical characters which can, be observed are known as qualitative characters., eg, species composition stratification, periodicity,, growth forms, dispersion, life forms., Synthetic characters are generalisations or, abstractions which are derived from analytical, characters, eg, constancy, fidelity, pattern,, dominance, physiognomy., , BIOTIC OR ECOLOGICAL SUCCESSION, l, , l, , l, l, , l, l, l, , l, , Biotic or ecological succession (Hult, 1885) is the, natural development of a series of biotic, communities at the same site, one after the other, till a climaxot community develops which does not, evolve further because it is in perfect harmony with, the environment of the area., A biotic community is influenced by biotic, factors, physicochemical factors and, geographical factors., The first biotic community which develops in a, base area is called pioneer community., Climax community is the stable, self perpetuating, and final biotic community that develops at the, end of biotic succession and is in perfect harmony, with the physical environment., Climax community is also termed as climatic, climax community., Climax community has maximum diversity and, niche specialization., The various biotic communities that develop, during biotic succession or the intermediate, communities between the pioneer and climax, communities are termed as seral or transitional, communties., The entire sequence of development stages of biotic, succession from pioneer to a climax community is, known as sere., Pioneer community (the first biotic community, on base area) ® seral community (the various, biotic community that develop during successsion, ® climax community (the stable, self, perpetuating and final biotic community), , l, , l, l, , l, , l, , l, , Changes that occur during biotic succession are –, –, Small short lived plants to large longlived plants., –, Unstable biotic community to stable biotic, community., –, Little diversity to high degree of diversity., –, Greater niche specialization., –, Increase in biomass., –, Increase in soil differentiation., –, Increase in human content of soil., –, Aquatic or dry conditions to mesic conditions., –, Simple food chains to complex food webs., Ecological succession is of two types – primary, and secondary succession., Primary succession is a biotic succession which, occurs on a previously bare or unoccupied area,, e.g., new exposed rock area, sand dunes, igneous, rocks, deltas etc., Secondary succession is a biotic succession that, occurs in an area from which a community has, been removed and where nutrients and, conditions for existence are present, e.g., cut over, forest, abandoned crop land, ploughed field., Successions are variously designated as , xerosere/lithosere (succession on bare rock),, hydrosere (succession in water), psammosere, (succession on sand)., Structure of hydrosere is depicted in the following, flowchart :, Climax forest community (mesophytic), e.g., Temperate mixed, Tropical rain, Tropical deciduous., Woodland stage, e.g., Salix, Poplus, Almus, Cornus., Sedge meadow stage, e.g., Juncus, Cyperus, Eleocharis, Carex., Reed swamp stage, e.g., Sagittaria, Phragmites, Typha, Scirpus., Floating stage, e.g., Nymphaea, Trapa, Azolla, Lemna, Wolffia, Pistia., , Submerged stage, e.g., Elodea, Hydrilla, Vallisneria, Utricularia, Potamogeton., Pioneer stage, e.g., Diatoms, Bacteria, Cyanobacteria, Green algae., l, , The structure of lithosere or xerosere is shown, by the following flow chart.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐőśńŐňΘ– ▲ĽŐŚĽĘ– ►ŐŇŇśňĽŚť– ·– ☼śĘĘĚřřĽŐň, , Climax forest community (mesophytic), , Importance of biotic succession, l, , Shrub stage, e.g., Rhus, Phytocarpus, l, , Herbaceous stage, e.g., Eleusine, Aristida., Moss stage, e.g., Polytrichum, Torula, Grimmia., , l, , Foliose lichen stage, e.g., Parmellia, Dermatocarpon, Crustose lichen stage (pioneer stage), e.g., Rhizocarpus, Rinodina, Lacanora., , Ø, , Ø, , Ø, , Ø, , Ø, , Ø, , Ø, , 541, , l, l, , Sequence of biotic succession is usually fixed., Ecologists can immediately recognize the seral stage, of a biotic community found in an area., It tells us how a biotic seral stage like grasses and, herbs of a pasture can be maintained by net allowing, the biotic succession to proceed further through, interference like grazing and fire., Information gained through biotic succession is, used in having controlled growth of one or more, species by preventing their superiors to invade the, area, eg., maintainance of teak forest., Dams are protected by preventing situation and, biotic succession to occur., It gives information about the techniques to be used, during reforestation and afforestation., , Some other types of succession, Autogenic succession After the succession has begun, in most of the cases, it is the community itself, which, as a result of its reactions with the environment, modifies its own environment and, thus causing, its own replacement by new communities. This course of succession is known as autogenic succession., Allogenic succession In some cases replacement of one community by another is largely due to forces, other than the effects of communities on the environment. This is called allogenic succession and it may, occur in a highly disturbed or eroded area or in ponds where nutrients and pollutants enter from outside, and modify the environment and in turn the communities., Autotrophic succession It is characterized by early and continued dominance of autotrophic organisms, like green plants. It begins in a predominantly inorganic environment and the energy flow is maintained, indefinitely. There is a gradual increase in the organic matter content supported by energy flow., Heterotrophic succession It is characterized by early dominance of heterotrophs, such as bacteria,, actinomycetes, fungi and animals. It begins in a predominantly organic environment and there is a, progressive decline in the energy content., Induced succession Activities such as overgrazing, frequent scraping, shifting cultivation or industrial, pollution may cause deterioration of an ecosystem. Agricultural practices are retrogression of a stable, state to a young state by man’s deliberate action., Retrogressive succession It means a return to simpler and less dense or even impoverished form of, community from an advanced or climax community. In most cases, the causes are allogenic, i.e., forces, from outside the ecosystem become severe and demanding. For example, most of our natural forest, stands are degrading into shrubs, savanna or impoverished desertlike stands by the severely grazing, animals brought from surrounding villages. Excessive removal of wood, leaf and twig litter also leads, to retrogressive succession., Cyclic succession It is of local occurrence within a large community. Here cyclic refers to repeated, occurrence of certain stages of succession whenever there is an open condition created within a large, community.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 542, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 59, , Ecosystem, l, , l, l, , l, , l, , Any unit which includes all the organisms, interacting with the physical environment so that, a flow of energy leads to clearly defined trophic, structure, biotic diversity and material cycle within, the system is known as an ecosystem., The term ecosystem or biocenosis was coined by, Sir Arthur Tansley in 1935., Ecosystems can be recognized as self regulating, and self sustaining units of landscape that may, be terrestrial or aquatic., Forests, grasslands, and deserts are examples of, terrestrial ecosystems. The aquatic ecosystems, can be either freshwater (ponds, lakes, streams),, or saltwater (marine esturaries) types., Ecosystem may be natural (forest, sea), if, developed under natural condition or artificial, (garden, agriculture) if created by man., , Components of ecosystem, l, l, , l, l, , l, , l, , An ecosystem has two basic components : abiotic, (nonliving) and biotic (living organisms)., Abiotic components include inorganic substances, or minerals (standing state or standing quality),, organic substances and different climatic, conditions like temperature, pH, light, etc., Biotic components include producers, consumers, and decomposers., Producers are autotropic, generally chlorophyll, bearing organisms, which produce their own food, (high energy organic compounds) by fixing light, energy in the presence of simple inorganic abiotic, substances, eg. green plants, yellow green algae,, brown red algae, algal protist., Consumer or phagotrophs are heterotrophic (the, food is produced by other living organisms),, organisms, which generally ingest their food., Consumers are of three types primary, , l, , l, , l, , l, , consumers, secondary consumer and tertiary, consumers according to the nature of their feeding, habit., Primary consumers are herbivores that directly, feed on producers i.e., green plant, e.g., rabbit, deer,, sheep etc., Secondary consumers or primary carnivores are, the carnivorous animals that feed on the, herbivores, e.g., fox, snake, owl, peacock., Tertiary consumer or secondary carnivores are, the animals that feed on the secondary, consumers, e.g., lion, tiger etc., Decomposers or saprotrophs are other heterotrophic, organisms, consisting mostly of bacteria and fungi, which live on dead organic matter or detritus. (They, decompose the organic remains by secreting, extracellular digestive enzymes)., , Structure and function of ecosystem, l, , l, , l, , l, , l, , l, , Important structural features of any ecosystem, are – species composition, trophic structures,, startification, standing state and stunding crops., The structure of ecosystem can also be depicted, through food relationships of producers and, consumers., Trophic structure of ecosystem is a type of, producer consumer arrangement, in which each, food level is called trophic level., The producers occupy the first trophic level,, herbivores the second, and the carnivores, constitute the third trophic level., Stratification is the occurrence or vertical zonation, in the ecosystem and indicates the presence of, favourable environmental conditions., Stratification helps in accommodation of large, number and types of plants in the same area. It, also provides a number of microhabitats and
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 543, , ◄ĘŐřťřŚĚŇ, , l, , l, , l, , l, , l, , niches for various types of animals, Stratification is absent or poor where environmental, conditions are unfavourable. For example, desert, ecosystems have very few trees and shrubs., The amounts of nutrients, for example, nitrogen,, phosphorus and calcium present in the soil at any, given time, is known as the standing state., The standing states of nutrients differ from one, ecosystem to another, or with seasons even in the, same ecosystem., Standing crop is the amount of living biomass, present in an ecosytem. It indicates the productivity, and luxuriance of growth., The important functional aspects of ecosystems, are productivity, decomposition, energy flow,, nutrient cycling (described later), and stability., , Productivity, l, The productivity of ecosystem refers to the rate, of biomass production, i.e. the amount of organic, matter accumulated per unit area per unit time., l, Productivity is of two kinds primary and, secondary., l, Primary productivity refers to the rate at which, sunlight is captured by producers for the synthesis, of energyrich organic compounds through, photosynthesis., l, The rate of total production of organic material, is known as gross primary productivity., l, The balance energy or biomass remaining after, meeting the cost of respiration of producers is called, net primary productivity., l, Net productivity = Gross productivity – Respiration, and other losses., l, At the trophic level of consumers the rate at which, food energy is assimilated is called secondary, productivity., Decomposition, l, Decomposition involves breakdown of complex, organic matter by decomposers to inorganic raw, materials like carbon dioxide, water and various, nutrients., l, The process of decomposition occurs in three, steps – fragmentation of detritus, leaching action, and catabolism., l, Factors affecting decomposition are – chemical, nature of detritus, soil pH, temperature, moisture, and aeration., , l, , Decomposition process gives rise to two products –, humus and inorganic nutrients (= minerals)., , Energy flow, l, The energy flow and storage in an ecosystem, follows the basic laws of thermodynamics., l, In an ecosystem, energy is transferred in the form, of food, and this leads to degradation and loss of, a major fraction of food energy as heat during the, metabolic activities and a very small fraction, becomes stored as biomass., l, There is transfer of 10% of energy from one trophic, level to another., , Food chain and food web, l, , l, , l, , l, , l, , l, , All trophic levels in an ecosystem are connected by, transfer of food or energy. The transfer of food and, its contained energy from one trophic level (e.g., producers) to the next trophic level (e.g. consumers), is called food chain., Two types of food chains can be distinguished in, all ecosystems. These are grazing (predator) food, chain and detritus food chain., Grazing food chain extends from producers, through herbivores to carnivores, as, Grass ® Grasshopper ® Lizard ® Hawk., Detritus food chain begins with dead organic matter, and passes through detritusfeeding organisms in, soil to organisms feeding on detritusfeeders., The detritus food chain in lake is as , Freshly fallen litter (organic matter) ®, Decomposers or Saprobes, ® Detrivores ® Game, fish (top consumers)., Different food chains are often interconnected, e.g., a specific herbivore of one food chain may serve, as food of carnivores of several other food chains., Such interconnected matrix of food chains is called, food web., Example of different food chains, 1. Food chain in aquatic ecosystem, , Producers, Primary consumers or herbivores (zooplanktons as, dinoflagellates and copepods), Secondary consumers or primary carnivore (aquatic, insects, crustaceans and aquatic animals), Tertiary consumer or secondary carnivore (small fish), Tertiary carnivore (large fish squids)
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 544, , ŕďőĽę– ĐĽŐńŐĹť, 2. Food chain in terrestrial ecosystem, , A. In cropland, Producers crop plants, , B. Grass land, Producers (Grasses), , Grasshoppers and rodents, , Grazers (deer, cattle), , Snakes and lizards, , Lion, , Ecological pyramids, l, , l, , Hawk, C. Forests, Trees, , l, , Aphids, l, , Spider, Small birds, Hawk, 3. Detritus food chain, Detritus, , l, , Earth worm, , l, , Frog, , Sparrow, , Snake, , Falcon, l, , Peacock, Food web, , l, , Tertiary, Consumer, , l, l, , Secondary, Consumer, , l, Primary, Consumer, , l, Producers, , l, Decomposers, , l, , The graphical representation of trophic structure, of ecosystem constitutes ecological pyramids or, food pyramids where producers occupy base of, the pyramid and top consumers occupy apex of the, pyramid., The concept of ecological pyramids was, developed by Elton (1927)., The ecological pyramids are of three types –, pyramids of number, pyramids of biomass, and, pyramid of energy., Pyramid of numbers is graphical representation, of numerical strength of various populations in, different trophic levels per unit area of an ecosystem, with producers forming base, intermediate levels, forming intermediate tiers and apex formed by top, carnivores., Number of individuals is generally maximum at, the producer level in pyramid of number., Pyramid of biomass is graphic representation of, amount of biomass per unit area sequencewise in, rising trophic levels with producers at the base and, top carnivores at the apex., Biomass is maximum in producers. It is the amount, of living matter measured in terms of dry weights., Pyramid of energy is graphic representation of, energy per unit area sequencewise in various rising, trophic levels with producers at the base and top, carnivores at the apex., Maximum energy is found at producer level., Pyramid of number and biomass may be upright, or inverted, depending upon type of ecosystem, but pyramid of energy is always upright because, energy of the production is always more than, primary consumers and so on, i.e., energy goes on, decreasing., All the ecosystem are interconnected by flow of, energy and transfer of materials with the, neighbouring ecosystem or distant ecosystem., Only 1 4% of the total solar energy is utilized, by plants for photosynthesis and rest of the solar, energy is reflected back, absorbed by ground, water, and atmosphere., Sugar cane is the most efficient user of the solar, energy, i.e., 10 12%., Energy flow is unidirectional, i.e., from producers, to secondary consumers and not back.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ĘŐřťřŚĚŇ–, l, , l, , Energy goes on decreasing with each and every, trophic level, i.e., energy of the producers > primary, consumers > secondary consumers > tertiary, consumers., Lindemann gave the law of 10% for energy flow, (10% energy transfer law), i.e., only 10% of total, energy received by one trophic level is transferred, to next trophic level., , Ecological efficiencies, The ratio between the energy assimilated over the, energy available between two trophic levels is called, ecological efficiency., l, Ecological efficiencies may be expressed as, photosynthetic efficiency, net production, efficiency, assimilation efficiency and trophic, level efficiency., l, Photosynthetic efficiency is the percentage of, incident solar radiations trapped by producers to, perform photosynthesis and produce gross primary, productivity., Photosynthetic efficiency =, Energyin gross primary productivity, ×100, Energyin incident solar radiations, l, Photosynthetic efficiency is 1 5%. It can also be, expressed in relation to PAR when it is 2 10%., l, Net production efficiency is percentage of net, primary productivity in relation to gross primary, productivity. Tree species with large amount of non, photosynthetic biomass have lesser net production, efficiency than small sized producers., Net production efficiency =, Net primary productivity, ×100, Gross primary productivity, l, Assimilation efficiency is the percentage of food, energy assimilated for body building to total food, ingested., Assimilation efficiency =, Food energy assmilated, ×100, Food energy ingested, l, Ecological efficiency/trophic level efficiency is, the percentage of energy converted into biomass, by a higher trophic level over the energy of food, resources available at the lower trophic level., Ecological efficiency =, Energy converted into biomass at trophic level, ×100, Energy present in biomass at lower trophic level, , 545, , Biogeochemical cycles or Nutrient cycles or, Material cycles, l, , l, , l, , l, , l, l, , l, l, , l, l, , l, , l, l, , l, , l, , Nutrient cycles involves storage and transfer of, nutrients through various components of the, ecosystem so that the nutrients are repeatedly used., The term biochemical cycling is used for exchanges/, circulation of biogenetic nutrients between living, and nonliving components of biosphere., Biogenetic nutrients/biogeochemicals are essential, elements required by organisms for their body building, and metabolism which are provided by earth and return, to earth after their death and decay., There are two types of nutrient cycles – gaseous, and sedimentary., The gaseous type of nutrient cycle is generally, located in the atmosphere or the hydrosphere, eg,, carbon, oxygen, water, nitrogen, hydrogen., In the sedimentary type, the reservoir exists in the, earth’s crust, eg, phosphorus, calcium, magnesium., The cyclic representation of carbon assimilation by, green plants (photosynthesis) which then passes, into bodies of animals (plants are eaten) and finally, during respiration of plants and animals and, decompositions by microbes, the carbon dioxide is, returned back to the atmosphere is carbon cycle., Oxygen cycle is the cycling of oxygen between the, biotic and abiotic components of the environment., In the process of respiration oxygen is taken in by, living organisms and released into the atmosphere,, combined with carbon, in the form of carbon dioxide., Carbon dioxide enters the carbon cycle or is taken, up by plants for photosynthesis and during, photosynthesis oxygen is evolved by the chemical, splitting of water and returned to the atmosphere., In the upper atmosphere, ozone is formed from, oxygen and dissociates to release oxygen., The cycling of phosphorus between biotic and, abiotic components of the environments represents, phosphorus cycle., Inorganic phosphates (PO43–, HPO42–, or H2PO4), are absorbed by plants from the soil and bodies of, water and eventually pass into animals through food, chains., Within living organisms phosphates are built up, into nucleic acids and other organic molecules., When plants and animals die, phosphates are, released and returned to the abiotic environment, through the action of bacteria.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 546, , l, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Phosphates in aquatic environments eventually, become incorporated into and form part of rocks,, through a gradual process of erosion, these phosphates, are returned to the soil, seas, rivers, and lake., Phosphoruscontaining rocks are mined for the, manufacture of fertilizers, which provide an, additional supply of inorganic phosphate to the, abiotic environment., Cycling of sulphur between biotic and abiotic, components is sulphur cycle., Sulphate (SO42–), derived from the weathering and, oxidation of rocks, is taken up by plants and, incorporated into sulphurcontaining proteins,, passed along food chains to animals. Decomposition, of dead organic matter and faeces by anaerobic, sulphatereducing bacteria returns sulphur to the, abiotic environment in the form of hydrogen, sulphide (H2S) which can be converted back to, sulphate or to elemental sulphur by the action of, different groups of photosynthetic and sulphide, oxidizing bacteria., Though nitrogen is essential to all forms of life, the, huge amount present in the atmosphere is not, directly available to most organisms., It can, however, be assimilated by some specialized, bacteria and is thus made available to other, organisms indirectly., Nitrogen fixation is a chemical process in which, atmospheric nitrogen is assimilated into organic, compounds in living organisms and hence into the, nitrogen cycle., Microorganisms involved in nitrogen cycle are–, Rhizobium (symbiotic), Azotobacter, Clostridium, (non symbiotic bacteria), Nitrosomonas,, Nitrococcus (nitrifying bacteria), Bacillus,, Micrococcus (denitrifying bacteria)., , Raunkiaer’s classification of Plants, Raunkiaer (1934) has distinguished plants into five, forms on the basis of size, shape, branching, crown,, life span and perennation. These are –, (i) Therophytes. Annual plants which perennate, in the form of seeds., (ii) Cryptophytes. Perennial plants with, underground storage parts : (a) Geophytes., Subterranean perennating structures (root, root, tuber, bulb, stem tuber, rhizome, corm),, (b) Helophytes (Marshy plants). Perennating, structure are embedded in mud. (c) Hydrophytes., Aquatic plants., (iii) Hemicryptophytes. Perennating structures, occur at ground level. Aerial shoots die on the, onset of winter, e.g., rosette plants., (iv) Chemaephytes. Small plants of cold areas, where perennating buds or shoot apices lie at or, above the ground level., (v) Phanerophytes. Perennial herbs, shrubs and, trees, epiphytes, succulents, lianas, etc. where, perennating buds occur at 10 cm or more height, above ground level., , Biomes, l, l, , l, , Biomes are major ecosystems delimited by, particular geographical area or climate., Biomes are often classified in seven categories :, tropical rain forests, savannahs, deserts, temperate, grassland, temperate deciduous forests, taiga and, tundra., The major forest biomes in India are – tropical, rain forest biome, tropical deciduous forest biome,, temperate broadleaf forest biome and temperate, needle leaf (coniferous) forest biome (taiga)., , Table : Major biomes of the world, 1., , Biome type, Annual temp/weather, Tropical rain forest 23 27°C, , Annual rainfall Important features, Multi storied vegetation (5 distinct layer, 200 350 cm, of vegetation)., Shows maximum biodiversity lianas,, epiphytes, trees show root buttress., Trees include ebony, mahagony,, cinnamon, fig, rubber etc. Palms,, plantains, bamboo occur here and there., Fauna consists of deer, goat, antelope,, elephant, snakes, lizards, parakeet etc., , contd....
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ĘŐřťřŚĚŇ, , 2., , Savannahs, , Warm climate, , 90 150 cm, , 3., , Deserts, , Hot (Thar, Sahara) cold, (Gobi), , 25 cm, , 4., , Temperate, grassland, , Hot summer, cold winter, , 5., , Temperate, deciduous, (broadleaf) forest, , 6 – 20ºC / Warm summer,, cold winters, , 6., , 6 – 15ºC / Pleasant, Taiga (northern, coniferous forest) summer, chilled winter, , 7., , Tundra, , Long cold winters, short, summers, , 547, , Tropical open grass land with shrubs and, trees. This biome supports buffalo, tiger,, zebra, mites, grasshopper, ants, beetles., , Succulent plants, deep rooted trees and, shrubs, show allelopathy (secrete some, chemicals substances that inhibit the, growth of other plants), show poor, biodiversity., Mostly leguminous herbs, scattered, 25 75 cm, bushes, occasional trees, extensive root, system. eg. Prairies of USA, pampus of, South America, Steppes of Eurasia,, tussocks of New Zealand, veldts of South, Africa, Downs of Australia., Fauna Deer, elk, bison, wolf, sheep,, rabbit, mice, burrowing owl etc., Dominant trees are oak, birch, maple,, 100 250 cm, beech, elm, magnolia, poplar, chestnut etc., shrubs, herbs, ferns, mosses, lichens,, grasses, vines etc. are seen. Fauna consists, of deer, fox, rabbit, hare, snakes, lizards,, salamanders, owls, sparrows etc., Gymnosperm with cone shaped canopy,, 50 170 cm, have needle shaped leaves. Pine, Deodar,, cypress, Spurce etc. Larch, Juniper, Fir,, Hemlock and Yew also occur at places., Lichens, mosses, fern, herbs are abundant., Fauna includes wolf, deer, rabbit, hare, elk,, squirrels, porcupine etc., Less than 25 cm Encircles the top of the world. Scattered, patches of grasses, sedges, lichens, low, diversity, low productivity. Amphibians, and reptiles are absent, common animals, are lemming, snow grouse, snow owl,, arctic fox, polar bear, reindeer, arctic hare.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 548, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 60, , Natural Resources and Their, Conservation, l, , Natural resources, also called earth resources,, are those living and nonliving resources of the, earth (including atmosphere, hydrosphere and, lithosphere) which have the potentiality to be used, by human being to fullfill their requirements of, food, shelter, and clothing etc., , l, , Of the different types of inexhaustible, renewable, exhaustible and non renewable exhaustible, natural resources, the most important resources, are energy, water (fresh water and marine), land,, soil, mineral and organisms., , Natural resources, , classified on the basis of, Chemical nature, , Abundance and availability, , Organic, Inorganic, Includes water, air,, Includes plants, minerals, fuels,, animals, microbes,, metalliferous stones, fossil fuels, etc., , Mixture, of organic, and inorganic, Includes soil, , Inexhaustible, * Occur in unlimited quantities, * Not likely, to get exhausted by man's use, * Eg., air, clay, sand, solar energy, wind power etc., , Presence or absence, in different countries, , National, Minerals, land, , Multinational International, Rivers, lakes,, Sunlight, air., migratory, animals & birds, , Exhaustible, * Occur in limited quantities, * If used indiscriminately are likely to get exhausted, * Eg., mammals, fossils fuels, forests etc., Two types, , Renewable, Nonrenewable, * Replenished, recycled or reproduced, * Likely to get exhausted with use because of its lack, * Must not be used beyond its renewability, of recycling, * Eg., forest (timber, rangeland), wild life (food), * Eg., fossil fuel (coal, petroleum, natural gas),, agricultural systems (food & fibre), underground, minerals, biological species., water, soil fertility (inorganic nutrients)., Flow chart : Classification of natural resources, , ENERGY RESOURCES, l, , All the natural resources that provide us with energy, in one form or the other are included in the energy, resources., , l, l, , Animal power is renewable conventional energy, resource got from draught animals., Draught animals [= draft animal used for its physical, (i.e muscular) power] are used in transport,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░ŕďń– ☻ĚřŐśŕĘĚř– ďňę– ♀ĺĚĽŕ– ►ŐňřĚŕŢŐň, , l, , l, , l, l, , l, l, , drawing water and agriculture, e.g., bullocks,, buffaloes, camels, horses., Fuel wood is a renewable conventional resource, used for cooking and heating in villages, remote, areas, urban poor, wayside dhabas., In India, annual consumption of firewood is around, 300 million m3 with natural availability being only, 60 million m3. The rest is got from excessive tree, felling leading to deforestation., Organic wastes constitute a renewable resource, that mostly include animal & human waste., Animals wastes include cattle dung, droppings of, sheep and goat, poultry litter, slaughter house wastes, fishery wastes., Humans wastes include night soil, urine, food, wastes, domestic residue., Organic wastes can be more profitably be used in, generation of biogas., , l, l, l, l, , l, l, , l, , Table : Different categories of energy resources, Renewable, , – Which are regenerated by, natural process, eg.,, biomass energy, solar, energy, hydropower, wind, power, tidal, geothermal., Nonrenewable, – Which do not get, regenerated or recycled, eg., fossil & nuclear fuel., Conventional energy – In common use (animal, power, fuel power, fossil, fuel and hydroelectric, energy)., Nonconventional – New or not in common, use (solar energy, nuclear, energy, wind, geothermal,, tidal)., Commercial energy– Energy which can be, transported and traded,, eg., electricity, fuel, solar, energy., Noncommercial – Available locally, not, transported and traded, Biomass energy, – Indirect solar energy i.e.,, trapped in the form of, organic matter., Nonbiomass, – Direct solar energy, wind, energy, hydropower,, geothermal energy., , l, , l, , l, l, , l, , l, , l, , l, , 549, , Biogas contains 50 70% methane, 30 40%, CO2, traces of H2, H2S and N2., Agroindustries include bagasse, bran, oil cakes,, press mud, saw dust., Forest residue include fallen twigs, leaves, bark,, stumps and roots., Crop residues include crop stubble, straw, weeds,, cotton and jute, sticks, husk, corn cobs, fodder, waste. Dried dung cakes are used for heating and, cooking., Energy plantation is growing of firewood trees, on nonforest and nonagricultural lands., Energy cropping is growing crops which yield, fuel. Alcohol can be obtained from potato,, sugarcane, maize and tapioca. Yield of alcohol is, 50% of sugar/starch concentration., Gasoline with 10 20% ethanol can be used in, conventional internal combustion engines, without much alternation and the mixture is called, gasohol., Fossils fuels are nonrenewable conventional, energy resources found inside earth’s crust where, they have been formed through heat and, compression on forests and other organic matter, buried underneath due to earthquakes, landslides,, lava, etc., Fossil fuels can be solid (coal, lignite), liquid, (petroleum) or gaseous (natural gas). The oldest, coal deposit are anthracite (80% carbon, 300 million, years back). Others are lignite (50 65% carbon), and bitumen (less than 40% carbon)., Fossil fuels provide for 70% of total energy needs, of the world and 87.4% of all commercial energy., Hydroelectric power is cheap, conventional and, almost inexhaustible source of energy where falling, water (now flowing also) runs turbines to generate, power., This power requires dam/reservoir building which, destroys forests, wildlife and displaces several, villages., There is increased salt content of water, higher, incidence of waterborne disease besides developing, water pressure which may cause earthquakes., Nuclear energy is nonconventional, non, renewable resource. Nuclear fission (now fusion, also) of selected radioactive materials (like, uranium235) yields large amount of heat energy., The common fuel used in atomic reactors is
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 550, , l, l, l, , l, , l, , l, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , uranium. Fast breeder reactor can use thorium., Some nuclear reactors of India are at Kota,, Tarapur, Narora & Kalpakkam., Solar energy is inexhaustible nonconventional, resource., Its use is yet to pick up because of requirement of, back up system to store and generate electricity, during night and during cloudy days., There are three methods of harnessing solar, energy direct heating (e.g., solar cookers),, thermal power plants (steam generation of heating, salt water), and photovoltaic conversion., Photovoltaic cells are very small semiconductors, of silicon, gallium, arsinide or cadmium telluride, which have electron surplus and electron deficient, regions., Wind energy is an inexhaustible resource which, was used in very old times in grinding grains,, lifting water and propelling ships., The instrument that converts wind energy into, electric energy is called wind mill., Geothermal energy is a nonconventional source, of energy where heat present in hot interior rocks, or hot water coming out of them is used for, generating electricity., Tidal energy is a nonconventional inexhaustible, source of energy. Tides moving in narrow areas are, allowed to run dual flow turbines., Low heat turbines connected to a sloping ramp, are used to convert wave energy into electricity., , WATER RESOURCES, l, l, , l, , Water is the main constituent of hydrosphere. It, is a renewable resource., 3/4 surface of Earth is covered by ocean which, contains 97.5% Earth’s water in strongly saline, condition. The rest contains the following – fresh, water (2.5%); frozen water (1.97%), ground water, (0.5% of fresh water); rivers; & lakes (0.02%);, soil (0.01%); and water vapour (0.001%)., Water resources are broadly categorised as fresh, water and marine or ocean water., , Fresh water resources, l, , Fresh water is a major renewable inorganic, resource which is an essential component of all, living beings, a habitat for several organisms,, determinant of vegetation and climate, floods and, , l, l, l, , l, l, , l, , l, , l, , l, l, , droughts, required for drinking, bathing, washing,, cooling, construction work, disposal of sewage and, industrial effluents, irrigation, etc., An average modern human being requires 350 , 700 litres of fresh water per day., Fresh water occurs in ponds, lakes, streams, river, & underground pools., At most of the other places more water is withdrawn, from surface and subsurface reservoirs than their, recharging. As a result many wetlands have dried, up and ground water is becoming scanty at many, places., Excessive irrigation in arid/semiarid areas increases, soil salinity., Over withdrawal of ground water in coastal regions, results in movement of saline water from sea in, underground aquifers, resulting in spoilage of water, quality., Deforestation, especially in the hilly areas has, reduced water absorption, storage in catchment, areas, greater incidence of soil erosion and floods, during rainy season., Water is seldom available in the pure form because, it is a general solvent of atmospheric gases and, several solid substances which, therefore, get, dissolved into it., Rapid evaporation of water, as in semiarid areas,, brings salts to the surface and, therefore, gives rise, to soil salinity., Hardness of water gives rise to soil salinity., Hardness of water is due to the presence of salts., Salts present in water shorten the life of cooking, utensils, water heaters, boilers, steam turbines, etc., A salt content of upto 3.5 gm/litre of water is safe, for irrigation. Beyond this concentration the water, becomes harmful to crops., , Conservation & management of fresh water, resources, l, A number of measures are required for optimum, utilisation and conservation of fresh water, resources., l, Assured irrigation is available to only 40% area as, compared to over 90% in advanced countries., l, There is a lot of wastage of agriculture water, because only 50% of water supplied to soil is useful,, the rest goes waste. Bricklining of irrigation, channels and sprinkling technique of irrigation are, recommended to save water.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░ŕďń– ☻ĚřŐśŕĘĚř– ďňę– ♀ĺĚĽŕ– ►ŐňřĚŕŢŐň–, l, l, , l, l, , l, , l, , l, l, , Industry wastage should be reduced and waste, water can be recycled., Domestic water supply wastage should be reduced., Waste water should be treated and used in irrigation, and other purposes., Rainwater harvesting, surface storage and, recharging of ground water should be carried out., Afforestation helps in preventing soil erosion,, reduces surface run off, retains water and, protects water sheds for continued water supply., Dams and reservoirs can be constructed to control, floods and ensure round the year supply of water, besides generation of electricity., Through desalination, sea water and saline, underground water can be converted into fresh, useful water., Canals are made to carry water in arid and semiarid, area., Desiltation, dredging of water bodies should be, undertaken regularly to prevent decrease in capacity, for storage., , Marine or Ocean resources, l, , l, l, , l, l, , l, , l, , Oceans occupy 71% of earth, constitute 97.5% of, total water, manufacture 85% of total biomass,, function as heat bank, source of common salt, cloud, formation, biogeochemical cycles, tidal power,, offshore petroleum fields, a source of navigation, and dumping ground with rivers., Oceans contain algal resources, animal resources, and minerals., Oceans contain a large variety of algae from minute, microscopic unicells to large kelps reaching a length, of 100 150 m (e.g., Macrocystis). All types of, algae occur in sea, viz. green, brown, red, blue, green, etc., A number of marine algae have been used as, human food., Animals are even now given fresh or processed sea, weeds, e.g., green algae Ulva and Caulerpa, brown, algae Laminaria,Alaria, Macrocystis and Sargassum,, red algae like Porphyra or Laver, Rhodymenia or sheep, weed, Chondrus or Irish moss., Marine algae are also used in preparation of, manure alongwith fish shells and animal, droppings., Important gels are obtained from marine algae,, eg., carageenin (red alga Chondrus), funori (red, alga Gloiopeltis), algin (brown algae Fucus,, , l, , l, , l, l, , l, , l, , 551, , Laminaria, Sargassum), agar (red algae Gelidium,, Gracilaria)., Marine fish are a good source of food besides, providing fish glue, fish metal, fish protein and, vitamins. Depending upon the place of catching, there are two categories– demersal (at or near, bottom) and pelagic (at or near surface)., The edible molluscs are mussels, clams and oysters., Pearl oyster, a source of pearls, is also reared to, obtain pearls., The edible crustaceans are crabs, lobsters and, prawns., Economically important mammals are dolphins,, porpoises and whales which provide meat, skin,, ivory, oils, frozen glands, etc., Food fish is the term used for all types of edible, aquatic animals because the major proportion is, that of fish. India catches 3.9 million tonnes of, food fish from sea out of the total of 73 million, tonnes world wide., Common salts is extracted from sea water by, concentration in salt pans in coastal areas. In old days, some minerals were obtained from sea weeds, eg.,, iodine (Fucus, Laminaria), bromine (Rhodomela)., Oceans also contain mineral concentrates, e.g.,, manganese nodules, phosphate nodules., , LAND RESOURCES, l, , l, , Land is the solid exposed crust of earth that, supports plants, animals and human beings and is, the source of minerals., Land is largely covered with natural forests,, grasslands, wetlands and man made urban &, rural settlements along with agriculture., , Forests, l, , l, , l, l, , Forests are the vast natural resources dominated, by trees and provide for mankind with fuel,, fodder, timber, paper, raw material, water yield, and animal product., Wood land is closer to human habitat with open, canopy (overhanging shelters) and managed by, human beings., Forestry deals with establishment, protection,, management and exploitation of forests., Silviculture is the branch of forestry that deals, with the establishment and cultivation of forest, plants like teak, sal, kel, sheesham etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 552, , l, , l, l, , l, , l, l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , 3 major functions can be associated with forests, are –, –, Productive functions : Provide a number of, articles of economic use, e.g., wood, fruit,, alkaloids, essential oil, latex etc., –, Protective functions : Provide protection from, excessive cold, heat, drought, noise, conserve, water and soil., –, Regulative function : Regulate biogeochemical, cycles, checks flood and drought etc., Deforestation is the falling down or removal of, forest trees., The major causes of deforestation are – jhuming, (shifting cultivation); construction of hydroelectric, projects; forest fires; construction of roads and, railways and canals; over grazing of cattles in forest, areas; requirement of wood., Impact of deforestation are – shrinking fuel food;, decrease in availability of timber; soil erosion; flash, floods during rainy season; siltation; causes, drought; loss of biodiversity and germplasm;, amount of rainfall decreases; increases atmospheric, CO2 content and causes global warming; uprooting, and loss of livelihood of tribals., Reforestation or afforestation is planting of more, trees., Conservation of forests aims at management of, forests in such a way so as to maintain them at, optimum form and derive optimum sustainable, benefit for present as well as future generations., Two major strategies are adopted – protection or, conservation forestry, and production or, commercial forestry., Protection or conservation forestry engages, protection of degraded forests to allow recoupment, of their flora and fauna. Well stocked forests are, managed scientifically for producing timber and, other forest products without causing any negative, environmental impact on forests., Commercial forestry is of three types social, forestry, agroforestry and production plantation., Social forestry is the raising quick growing, multipurpose plants in common village lands for, fodder, fire wood, and small timber. This, programme was started in 1976., Urban forestry is the plantation of fruit, flower, and shade bearing plants in urban areas to reduce, pollution., , l, , l, l, l, , l, , l, l, , l, , Agroforestry is the plantation of multipurpose, trres/shrubs along with crops for stabilizing soil,, need of fodder, fruit and timber of the community., Agroforestry includes taungya system, shifting, cultivation or jhum (or slash and burn) system., In taungya system, agricultural crops are grown in, between rows of planted trees like sal and teak., Jhum or shifting cultivation allows regrowth of, forests after clearing and cultivation in an area for, a few year., Conservation of forests is done by –, –, Sustained yield block cutting. Cutting is, allowed only in nonvulnerable forests at a, rate which is equal to their regeneration, capacity., –, Van mahotsava : A special function of tree, plantation., –, Prevention of scraping and litter removal., –, Advanced silviculture., –, Control of weeds., –, Pesticides., –, Fire fighting equipment., –, Census., –, Supervision and surveying., –, Economy in extraction and use of timber., –, Water shed protection., –, Alternate source of fuel for villagers., –, Controlled grazing., –, Chipko movement : A movement initially, meant for protecting trees but now meant for, preservation of environment including habitat, and wildlife, it was started in 1973 in, Gopeshwar in Chamoli district by Sunderlal, Bahuguna. (A similar movement called, appiko movement started in 1983 in, Karnataka)., For conservation of forests, different type of laws, have been implanted., The basic objectives of Forest act, 1927 are –, (i) establishment and management of three types of, forests village forests, reserved forests and, protected forests. (ii) protection of nongovernment, forests and forests land against over exploitation, and denudation. (iii) control of movement of forest, products. (iv) control of grazing., Reserve forests are forests grown over ecological, fragile areas near water regimes and no cutting, down of trees is allowed.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 554, , l, , ŕďőĽę– ĐĽŐńŐĹť, , preservation and restoration of ecological balance., (ii) check of soil erosion and denudation of, catchment areas. (iii) checking on spread of sand, dunes. (iv) increase in forest tree cover through, massive afforestation and social forestry, programmes. (v) steps to create massive peoples, movement for afforestation, management and, protection of forests. Already about 14.25 million, hectares of degraded forests are being restored,, managed and protected by 63,000 Joint Forest, Management Committees., The moral basis of human responsibility towards, environment is called environmental ethics., , l, , Grassland, l, , l, , Grassland or rangelands are the land areas, dominated by grasses and herbs and provide forage, to cattle and support wildlife., Major causes of degradation of grassland are –, –, Agriculture. Grasslands are large plain tracts, with good humified fertile soil cover. They, have been converted into agricultural lands at, many places, e.g., North American praires., –, Overgrazing. With the conversion of parts of, fertile grasslands into agricultural land the, remaining less fertile grasslands are used for, grazing of animals. As a result grazing pressure, increases. In arid and semiarid areas of India,, the grazing cattle population is 2 – 10 times, the capacity of grasslands, trampling and, compaction., –, Scraping. At many places, grassland is scraped, to collect grass for feeding the cattle and, storage as dry hay. The scraped soil is exposed, and degrades quickly., –, Fires. Occasional fires are common in, grasslands. Fires burn down the grass and, expose the soil for growth of other plants and, erosion., –, Soil erosion. Whenever plant cover is removed, by overgrazing, scraping and fire, the soil is, exposed to run off water and dry wind. They, cause removal of top soil., –, Desertification. Conversion of fertile forest,, grass covered or agricultural land into barren, sandy or arid areas is called desertification., It occurs when denuded areas dry up due to, prolonged drought and dry soil is exposed to, wind erosion. Very fine soil particles are, , picked up by the wind and carried as dust., The coarser particles left behind are of the, size of sand. Therefore, wind erosion makes, the soil sandy. The sandy soil is unstable as, sand shifts due to surface creep caused by, wind. This produces sand dunes. The sandy, and dusty wind deposits its dust and sand over, adjacent fertile areas and converts the same, into desert. Therefore, desert once formed, spreads over its boundaries., Grassland management can be done by the, following –, –, Grazing should be limited to only that number, of animals which can be comfortably, supported by a piece of grassland., –, Grasslands should be closed to grazing when, new plant growth is to take place, like rainy, season., –, A grassland should be divided into blocks with, each block be allowed to be grazed on, rotational basis, this allows other blocks to, recover., –, Reducing loss of soil and water from the, grassland by contour bunding., –, Occasional controlled burning of dried mulch, to promote release of nutrients and prevent, growth of trees and shrubs., –, Removal of tree seedlings, bushes, shrubs, and weeds which tend to reduce productivity, of grasslands ., –, Occasional seedling with high yielding, leguminous herbs for maintaining soil fertility., , Wetland, l, , l, , l, , Wetlands are low lying flat, marshy, swampy or, peat lands which may get inundated upto depth of, six meters., Wetlands may be natural or artifical, temporary, or permanent, fresh water, brackish or saltish, with static or flowing water., Conservation of wetlands can be done by , –, Preparation of inventory of all wetlands., –, Identification of wetlands of critical, importance for immediate conservation., –, Checking dumping of wastage in wetlands., –, Bordering the wetlands with growth of trees, and shrubs so as to prevent excessive flow of, silt and nutrients.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ░ŕďń– ☻ĚřŐśŕĘĚř– ďňę– ♀ĺĚĽŕ– ►ŐňřĚŕŢŐň, , Table : Difference between fresh water and, marine wetlands., Fresh water wetlands, , Marine wetlands, , 1. They occur in land., , They occur in coastal, areas., , 2. The wetlands develop, in depressions where, rain water or flood, water can collect., , The wetlands develop at, the mouths of rivers or, shallow areas along the, sea coasts., , 3. Salt content is low., , Salt content is high., , l, , l, , l, , 4. Help in charging They have no such role., groundwater., 5. They are abode of Marine wetlands have, several resident birds no such function., and halting grounds, for migratory birds., 6. Are of 3 types Are of 2 types estuar, marshes, swamps, ies, mangroves., riverine., , SOIL RESOURCES, l, , l, l, , l, , l, l, , l, l, , l, , Soil is the upper weathered humus containing, part of earth’s surface that supports plant life on, earth., The study of soil is called pedology., Soil consists of the inorganic materials derived, from rocks; the organic material derived from dead, organism; the air & water occupying the pores, between the soil particles which are loosely packed;, small organisms like bacteria, fungi, nematodes, etc., The removal of the top fertile layer of soil by, agents like water, wind, etc. is called soil, erosion., Natural or geological erosion is extremely slow, removal of top soil due to rain water or wind., Human induced erosion is caused by removal of, plant cover through overgrazing, litter collection,, tree felling and leaving the soil unprotected during, agricultural operations., Sheet erosion is the removal of extremely thin layer, or sheet from soil surface., Rill erosion is the development of finger like or, groove like narrow depressions or rills due to, running water., Deeper, wider channels developed by cutting power, , l, , l, , l, , 555, , of running water, 15 30 m deep gullies, are called, ravines., Wind erosion is caused by carrying of very fine, soil particles as dust, saltation and surface creep of, larger particles., Soil conservation refers to various soil and, crop management practices that can minimize, er os i on & red uce nu tri ent de pl eti on of, agricultural soils., Soils erosion can be prevented or controlled by –, –, Crop rotation : The practice of sowing, different crops, usually legume and, nonlegume, in successive seasons on the same, piece of land for maintaining soil fertility., –, Mixed cropping : Growing two or more crops, stimultaneously on the same land., –, Covering of harvested field with plant litter, of polyethene (LDPE or low density, polyethylene) in order to decrease runoff,, prevent growth of weeds and retention of water, (called mulching)., –, Strip cropping : Sowing of perennial crops, alternating with annuals, or annuals with, different seasons of sowing and water., –, Contour Bunding : Raising small bunds on, edges of fields to prevent loss of top soil, through water or wind., –, Growth of several alternate rows of trees and, shrubs at right angles to prevalent direction of, wind for reducing its speed and preventing, carrying of soil particles., –, Afforestation and Reforestation : Plantation, of forests., –, Grazing is allowed in certain seasons and, only for limited number of animals., –, Contour ploughing – Ploughing is carried, out at right angles to the slope., –, Depending upon the climate and availability, of moisture, soil is seeded with drought, resistant grasses and leguminous herbs., Reduction of soil fertility is caused by water, logging, pH change, salination, leaching of, minerals, overgrazing and nonculture., Restoration of soil fertility can be done by green, manuring, rotation of crop, irrigation, maintenance, of soil pH and stoppage of overgrazing., Presence of excess salt (sodium potassium and, magnesium) is called soil salinity.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 556, , ŕďőĽę– ĐĽŐńŐĹť, , ORGANISM RESOURCES, , MINERAL RESOURCES, l, l, , l, , l, , l, , Minerals are largely nonrenewable inorganic, resources that are presently mined from lithosphere., Minerals are raw materials for industry in, manufacture of appliances, tools, implements and, materials required for every sector of human society., Minerals are of two types metallic (e.g., iron,, copper, aluminium, gold) and nonmetallic (e.g.,, asbestos, feldspar, phosphates, sand, salt)., Their (minerals) average abundance is called clarke, (e.g., 8% for aluminium, 0.001% for lead)., Wherever minerals occur in quantities many times, larger than their clarke, an ore body is present, from where the mineral is extracted., Mineral conservation may be done by –, –, Reuse of an article several time, –, Recycling of metals through reprocessing, –, Scarce metals can be substituted by more, abundant metal; and, –, Use and throw tendency should be checked., Table : Important minerals and their uses., , Mineral, Metal elements, Auminium, Chromium, Copper, , Gold, Iron, Lead, Manganese, Nickel, Platinum, Potassium, Silver, Uranium, , l, , l, , l, , l, l, , Selected uses, Sructural material, packaging, Chrome plate, steel alloys, Alloy material in gold jewellery,, silverware, brass and bronze, electric, wiring, pipes, cooking vessels, Jewellery, dentistry, alloys, Primary component of steel, Pipes, battery electrodes, pigments, Alloy steels, disinfectants, Coins, alloys, metal plating, Jewellery, equipments, industrial, catalyst, Fertilizer, glass, photography, Jewellery, vessels, photography, alloy, Nuclear bomb, electricity, tinting, glass, Cans/containers, alloys, Brass, electrodes, medicine, , Tin, Zinc, Nonmetal elements, Medicine, fertilisers, detergents, Phosphorus, Insecticide, rubber types, medicine, Sulphur, Liquid metal, element, Thermometer, dental inlays, electric, Mercury, switches, , l, , Plant constitute a renewable organic resource, which, being producers, form the basis of biotic, existence and manmade environment. They provide, us food, sugar, fibres, drinks, condiments,, medicines, timber, pulp for paper, rubber, gums,, resins, tannins, alcohol and organic acids., Plants maintain balance of CO2/O2, provide, shelter to numerous animals, moderate the, climate, increase periodicity of rainfall and, prevent soil erosion., Cultigens are plants whose ancestry has become, obscure and which cannot survive in nature without, human help, e.g., cabbage, maize etc., Eichhornia crassipes have became a serious weed, used in India., A few animal resources are domesticated and, exploited for–, –, Food : Fowls and ducks (eggs, meat), goat,, sheep, rabbit, pig (meat), cow, buffalo,, reindeer, sheep (milk and meat), honey bee, (honey), fish, oyster, prawn, mussel (meat)., Animal protein is most suitable for human, beings, pets : Dogs, cats, pigeons, wool :, Sheep, Angora rabbit, Kashmiri goat, silk, (silkworm), lac (lac insect), musk (musk deer),, ivory (elephant), cantharidine (blister beetle)., –, Leather goods from hides, draught animals,, pollinators and disseminators, aboratory, animals, source of hormones., Microorganism resources are exploited for, various reasons as –, –, Saccharomyces cerevisiae, S. elliposidens,, Rhizopus oryzae and Mucor javanicus in, preparation of wines, whisky, rum, beer, cider,, brandy etc., –, Yoghurt from milk by Streptococcus, thermophilus, buttermilk by Streptococcus, cremoris, S.lactis and Leuconostoc, dextranicum., –, Food yeast Rich in protein, vitamins and, minerals., –, Different organic acids like acetic acid, citric, acid, lactic acid, and fumaric acid, antibios,, vitamins are obtained from microorganisims., –, Pseudomonas and Clostridium help in retting, of stem and leaf fibres., –, Bacteria help in nitrogen fixation; nitrification;, ammonification; curing of tea, tobacco, coffee etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐęĽŢĚŕřĽŚť–, , 557, , Chapter 61, , Biodiversity, l, , l, , l, , l, , l, , l, , l, , l, l, , Biodiversity (synonym for ‘life on earth’) or, biological diversity (GK bioslife, diversityforms), is the occurrence of different types of ecosystem,, different species of organisms with their biotypes, and genes adapted to different climates,, environments along with their interactions and, processes., Biodiversity includes three interrelated, hierarchial levels. These are – genetic diversity;, species diversity; and community or ecosystem, diversity., Genetic diversity means variation of genes within, the species; the differences could be in alleles, (different variants of same genes), in entire genes, (the traits determining particular characteristics) or, in chromosomal structures., The genetic diversity enables a population to adapt, to its environment and to respond to natural, selection., The amount of genetic variation is the basis of, speciation (evolution of new species). It plays an, important role in the maintenance of diversity, at species and community levels., Genetic diversity is the basis of formation of new, species. The greater is the genetic diversity of a, species, the higher is its efficiency to adapt. The, greater the diversity the wider is the geographical, distribution., Lower genetic diversity within a species or variety, may be useful for uniformity in yield as a well as, higher yield., The variety in the number and richness of the species, of a region is known as species diversity., The number of species per unit area is called species, richness and the number of individuals of different, species represents species evenness., , l, l, , l, , l, l, , l, , l, l, , l, , l, , l, , Actually species diversity is the product of species, richness and species evenness., Diversity at the level of community and ecosystem, has three perspectives i.e. alpha(a) diversity, beta, diversity and gamma diversity., adiversity, also known as withincommunity, diversity, means diversity of organisms sharing the, same community/ habitat., adiversity is dependent upon species richness, and evenness., Such diversity shows a lot of competition,, adjustment and interrelationships among the, members of the same community., Beta diversity or between community diversity, means the rate of replacement of species along a, gradient of habitats or communities due to presence, of different microhabitat, niches and difference in, environmental condition., Gamma diversity is the diversity of the habitats, over the total landscape or geographical areas., The important factors causing loss of biodiversity, are – habitat loss, habitat fragmentation,, disturbance, overexploitation, pollution, exotic, species, intensive agriculture & forestry., Expanding population and development require, more industrial areas, extension of present towns, and cities, more area for agriculture, new roads,, canals, dams, etc. All these activities will result in, destruction of natural habitats (or habitat loss)., Destruction of habitat is the primary cause of, extinction of species. Grasslands were converted, into agricultural lands during colonisation of, America. New Zealand abounded in wetlands., In tropical areas human settlements required cutting, down of trees and burning of the remaining forests., Destruction of the habitat kills most of the, organisms.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 558, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Some organisms especially animals leave the habitat, but being alien in other habitats, they usually die, out there., Habitat fragmentation is the breaking of a large, habitat into smaller patches due to development of, agriculture, water body and other changes., The phenomenon of reduction in species diversity, in small patches is called insularization. Initially,, there may be increase in number of species in, patches but ultimately it decreases. This type of, decrease is called relaxation., Fragmentation reduces the core area and increases, the edge area., Species occupying the deep or interior portion of, the forests would be badly affected due to disruption, of their interrelationships., Most of them are relatively rare species (Gaston,, 1994) which tend to disappear as their habitat area, shrinks due to fragmentation., Forest patches having croplands, orchards,, plantation and urban settlements on their outskirts, are examples of fragmented habitats., Fragmentation of habitats (e.g., forest land, surrounded by croplands, orchards, plantation,, urban areas) results in disruption of complex, interactions amongst species, destruction of species, in the cleared regions, annihilation of species, restricted to deeper undisturbed parts of forests and, decreased biodiversity in the habitat fragments., Disturbance is alternation made in the habitat,, environment and the community of an area., Disturbance is both natural and anthropogenic., Natural disturbance is caused by natural calamities, like drought, excessive rain, landslides, floods, tree, falls, disease, defoliation by insects and dry weather, fires., Anthropogenic or manmade disturbance is, actually very high in intensity, rate and spatial, extent, e.g., tree felling, collection of litter, fire for, clearing forests., While some natural disturbances are beneficial for, biodiversity (Intermediate Disturbance Hypothesis,, Connel, 1978), large scale disturbance is harmful, to diversity. Corn and Bury (1989) found that timber, harvesting along the banks of streams reduced their, diversity., Overexploitation of any particular species reduces, the size of its population so that it becomes, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , vulnerable to extinctions, eg., hunting of animals,, collection of medicinal plants., Biological systems should not be exploited beyond, the degree of their renewability. Exploitation beyond, this level results in degradation and extinction of, the resource., Excessive tree felling in the forest, overgrazing,, uprooting of orchids and medicinal plants, hunting, of animals, etc. have resulted in degradation of, habitats and extinction of many species, e.g.,, Cheetah from India, Dodo from Mauritius. Both, orchids and medicinal plants have become, threatened plants., Pollution are harmful alterations made in our, surroundings by human activities like industrial, effluents, industrial emissions, automobile, emissions, pesticides, fertilizers, sewage, etc., Pollution load of our requirement is rapidly rising, so that it has already proved harmful to many, ecological systems., Acid rain (caused by excessive sulphur and nitrogen, oxide emissions) has destroyed more than 50% of, natural forests and several fresh water lakes in many, western countries., Oil spills in sea destroy plankton, algae, marine, animals and smearing of sea birds resulting in their, immobility and death. SO2 pollution of air kills, lichen population of the area. Pesticides often enter, food chains and undergo biomagnification. It caused, decline in population of fish eating birds and, falcons., Lead and other heavy metals entering water bodies, as effluents and wastes cause mortality in animals., Cattle regularly drinking such polluted waters may, get killed., Ducks, cranes and swans often die after taking in, spent shotgun pellets that fall in their aquatic, habitat., Nutrient enrichment of water bodies occurs by run, off from fields and sewage disposal. This causes, dense growth of plants. The phenomenon is called, eutrophication., Eutrophication leads to depletion of oxygen, death, of animals, accumulation of organic matter and, fouling of water., Any new species entering in a geographical region, are known as exotic (alien) species., Exotic species may cause disappearance of native
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐęĽŢĚŕřĽŚť, , l, , l, l, l, , l, , l, , l, , l, , species through changed biotic interactions. Like,, –, Water hyacinth (Eichhornia crassipers) was, introduced in Indian waters to reduce, pollution. It has clogged water bodies, including wetlands at many places resulting, in death of several aquatic plants and animals., –, Lantana camara (a straggling shrub) has, becomes a serious weeds which has replaced, many species in forests of U.P. and M.P., –, Eupatorium odoratum has reduced the, population of Tectona grandis in NorthEast., –, Parthenium hysterophorus has pushed out, several herbs and shrubs from open places in, the plains., –, Nile Perch, a large predator fish was, introduced in Lake Victoria of South Africa., It began to threaten the entire fresh water, ecosystem by feeding on small herbivorous, and detrivorous chichlid fish species which, were endemic to the aquatic system. Chichlid, species not only became extinct but finding, no food for itself, Nile Perch also died out., Exotic species on becoming invasive constitute, the second most potent factor (first being habitat, destruction) for extinction of species., With the pressure of increasing human population,, agriculture became both intensive and extensive., Extension of agriculture resulted in diminishing, of wetlands, grasslands and forests., Intensive agriculture is based on a few crops and, their few high yielding varieties and as a result, there is reduction in the genetic diversity. The, remaining varieties are disappearing fast. Similarly,, crops with smaller yields and returns are being, edged out of cultivation. It has decreased, biodiversity., Forestry is the tendency to grow economically, important trees in pure strands, e.g., sal, teak. It drives, away or annihilates other species found in forests., Today forestry means growth of exploitable forest, plants. There is, therefore, a tendency to grow only, these plants in almost pure strands., Other economically less important plants are being, ignored resulting in their extermination and hence, loss of biodiversity., Spread of agriculture at the cost of wetlands,, grasslands and forests and destruction of habitats, results in extinction of species., , l, , l, , l, , l, l, , l, , l, , l, l, , l, , 559, , Natural disturbance and degradation are caused, by spontaneous jungle fire, pest infestation,, defoliation by insects etc., Man made disturbance include felling of trees,, use of fire for clearing forest areas, collection of, litters and overexploitation of economically, important products., Extinction is the disappearance or elimination of, a species from earth. It is different from, disappearance of a local population which is called, extirpation., Complete extinction of a species results in complete, loss of genetic information contained in it., Extinction of species is a natural process when, older species disappear and new ones evolve to, take their place over the long period of time., A species becomes prone to extinction due to two, categories of attributes – drastic environmental, changes and population characteristics., Population traits which makes a species, susceptible to extinction are –, –, Large body size, e.g., elephant, rhinoceros,, Bengal tiger, lion, –, Small population size, –, Low reproductive potential, e.g., blue whale,, giant panda., –, Higher status of trophic level, e.g., bald eagle,, bengal tiger., –, Narrow range distribution or small, geographical range, e.g., woodland caribou., –, Lack of genetic variability, –, Inability to switch over to alternate foods., There are three types of extinction process – natural,, mass extinction and anthropogenic extinction., With the change in environmental conditions, some, species disappear and others, which are more, adapted to changed conditions, take their place., This loss of species, which occurred in the, geological past at a very slow rate, is called natural, or background extinction., Mass extinction is a catastrophic, widespread–, often global–event in which major groups of species, are wiped out over a relatively short period when, compared to normal (background) extinctions of, natural causes (in at least one case due to an asteroid, impacting the earth), in the earth’s history. During, these mass extinctions, certain groups of organisms, disappeared while others survived apparently
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 560, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , unscathed. And after each mass extinction, species, numbers rebounded as whole new groups of, organisms evolved and colonized the planet., Anthropogenic extinction is a manmade, extinction where an increasing number of species, are disappearing from the face of the earth due to, human activities. This extinction causes a very, severe depletion of biodiversity, especially because, it is occurring within a short period of time., IUCN is International Union of Conservation of, Nature and Natural Resources which is now, called World Conservation Union (WCU). It has, its headquarters at Morges, Switzerland., The species particularly susceptible to extinction, are : large body size (Bengal tiger, lion and, elephant); and small population size and low, reproductive rate (blue whale and giant panda)., The known and described number of species of all, organisms on the earth is between 1.7 and 1.8 million,, which is fewer than the 15% of the actual number., Wildlife Institute of India has divided the country, into ten biogeographical regions – Trans, Himalayas, Himalayas, Desert, Semiarid, Western, Ghats, Deccan Peninsula, Gangetic Plain, North, East, Coasts, Islands., Among the biogeographical regions of India,, Deccan peninsula has the most extensive coverage, of the Indian landmass (42%)., The most biodiversityrich zones are – Western, Ghats and North east, account for 4 and 5.2 percent, of the geographical area, respectively., TransHimalayas is cold desert with sparse, vegetation. It has a rich community of goat and, wild sheep besides snow leopard., NorthEast and Western Ghats have wild relatives, of number of cultivated plants like banana, citrus,, mango, pepper, etc., Most of the endemics restricted to a particular area, of a region occur in – NorthEast, NorthWest,, Western Ghats, Andaman Nicobar islands. Western, Ghats possess a very large number of endemic, amphibian species., In temperate region the climate is severe with short, growing period for plants, in tropical rain forest, the conditions are favourable for growth through, out the year., Degree of biodiversity shows two master, gradients – altitudinal and latitudinal., , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Biodiversity is minimum in the arctic region,, moderate in temperate area and maximum in, tropical regions. For example, the number of, species of vascular plants is 118236/0.1 ha in, tropical forests, 21–48/0.1 ha in temperate zone, and 0.0–10.0 ha in arctic area., The second master gradient of biodiversity is, observed when one ascends a mountain., Biodiversity is maximum at the base. It decreases, with the increase in altitude., Rise in altitude also decrease mean temperature, a, fall of 6.5ºC for every 1000 m increase in altitude., Lower temperature and greater seasonal variability, reduces diversity., Biodiversity is the source of food, medicines,, pharmaceutical drugs, fibres, rubber and timber., The diversity of organisms also provides many, ecological services which are responsible for, maintaining ecosystem health., Conservation of biodiversity is protection uplift, and scientific management of biodiversity so as to, maintain it at its optimum level and derive, sustainable benefits for the present as well as future, strategies., There are two basic strategies of biodiversity, conservation – in situ (on site) and ex situ (off, site)., All efforts should be made to preserve the species, that are endangered through out the range. The, threatened species should be given preference over, others in the conservation programme., [For more details on wild life conservation refer, chapter Wild Life & Conservation], Megadiversity centres are regions of world which, are extremely rich in species, especially the endemic, ones. Mittermeir and Werner (1990) have, recognized 12 megadiversity centres– India,, Malaysia, Indonesia, China, Zaire, Madagaskar,, Australia, Ecuador, Peru, Brazil, Columbia and, Mexico. India with only 2.4% of land area accounts, for nearly 8% species of the world., The concept of ‘Hot Spots’ of biodiversity was, developed by Norman Myers to designate priority, areas for in situ conservation., The criteria for determining hot spots are: number, of endemic species and degree of threat, that is, measured in terms of habitat loss.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 561, , ▲ĽŐęĽŢĚŕřĽŚť, l, l, , l, , l, , There are twentyfive hot spots identified, worldwide., There are two hot spots in India; they are (i), Western Ghats, and (ii) Eastern Himalaya; these, areas are rich in flowering plants, reptiles,, amphibians, swallowtailed butterflies and some, mammals, which show a high degree of endemism., Western ghats occur along the western coast of, India extending for almost 1600 km through, Maharashtra, Karnataka, Tamil Nadu and Kerala to, Srilanka. Rainfall is good., Forests lying at low elevation upto 500 m are, evergreen while those at moderate elevation, , l, , l, , (5001500 m) are semi evergreen. 1600 species of, plants are endemic to this area. Southern Western, Ghats are known as Malabar., It has high biodiversity as well as high degree of, threat perception to biodiversity. IUCN has, recognised three threatened areas – Agastyamalai, hills, Silent valley and Periyar National Park, (new Amambulam Reserve)., Eastern himalayas is meeting place of three, biogeographical regions– Indian, Malayan and, Chinese. It extends to Bhutan and through north, cast to Myanmar and is called IndoBurma hot, spot., , Table : Uses of Biodiversity, Used as, , Food, Source of fats, and oils, , Fibres, Drugs/medicines, , Asthetic value, , Sources, , Carbohydrate rich crop, wheat, corns, rice., Soyabean, coconut,, cotton, seed,, peanut,, s u n fl ow er, s es a m u m ,, safflower, rapeseed, mustard, and oil palm., Oil is also obtained from wild, gourd, bitter colocynth, jojoba., Cotton, flax, jute, hemp,, rosella, agave, abaca, and coir., Vinca rosea yields alkaloids, used for treatment of leukemia,, Papaver somniferummorphine, forpain, Cinchonaquinine(for, malaria), Taxus brevifolia taxol, for treating cancer. Rauwolfia, serpentinareserpine for blood, pressure and schizophrenia., Ecotourism, Birdwatching,, wild life pet keeping., , Used as, , Cultural benefits, , Ecosystem, services, , New varieties, (obtained from, crossing with wild, varieties), , Sources, , Sacred plants – Ocimum, sanctum (tulsi), Ficus religiosa, (Peepal), Prosopis cineraria, (Khejri), Sacred birds, snakes, are sometimes worshipped., Forests and oceans –, control climate & gaseous, temperature,, nutrient, cycling,conservation of water,, formation and conservation of, soil., Disease free rice plants are, obtained by crossing rice plants, with, Oryza, nivara, (wild), Potato resistant to late blight, (Solanum demissum), potato, mosaic virus, leaf roll virus, (Solanum acaule), nematodes, (S. spegazzeni) are also, obtained.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 562, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 62, , Pollution & Global, Environmental Changes, l, , l, , l, , l, , An undesirable change (may be physical , chemical, or biological) in air , water or soil due to excessive, accumulation of pollutant is called as pollution., The pollution by volcanic eruption, UV radiation,, soil erosion, dust storm, forest fire etc. are called, as natural pollution., The pollution caused by human beings (industrial,, water removal etc.) are called as anthropogenic, pollution., A pollutant is any substance, chemical or other factor, that changes the natural balance of environment., , l, l, , l, , l, , The increase in toxicity by reaction among the, pollutant is known as synergism., Pollution is different from contamination which, occurs in the presence of harmful organisms or, their products causing disease or discomfort., On the basis of emission of pollution, it can be, point source (from single point), line source (which, passes along a belt), area source (in mining area), and diffuse source (over a large area)., There are 5 types of pollution : air, water, land,, noise and radioactive pollution., , Pollutants, , on the basis of, Existence, Quantitative, those component, which become, pollutant when, its concentration, reaches beyond, a threshold value,, eg. CO, CO2, NO2, concentration in, the air, , Qualitative, do not occur, naturally in, nature, but, passed through, human, activities,, eg. DDT and, other pesticides, , Natural disposal, Biodegradable, quickly, degraded, by natural, means,, eg. sewage, , AIR POLLUTION, l, , Air pollution is the occurrence or addition of foreign, particles, gases or pollutants in the air which have, an adverse effect on human beings, animals,, vegetation etc., , Persistence, , Non, biodegradable, either do not, degrade or, degrade very, slowly in nature,, eg. mostly, inorganic, compounds, (like salts of heavy, metals, radioactive, materials etc.),, DDT, long chain of, phenolic chemical, etc., l, , Primary, pollutants, persists in form, in which they, are added to, the environment,, eg. plastic ware,, DDT, , Secondary, pollutant, formed by, interaction, among primary, pollutant, more, toxic than, primary pollutant,, eg. peroxyacyl, nitrates (PAN), and ozone, , The various causes of air pollution are –, –, Combustion of natural gas, petroleum, coal, and w ood in in dustries , automob iles,, aircrafts, railways, thermal pla nts,, agricultural burning, kitchens, etc. (soot,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐńńśŚĽŐň– ·– ◙ńŐĐďń– ◄ňŢĽŕŐňŇĚňŚďń– ►ĺďňĹĚř, , l, , l, , l, , l, , l, , l, , l, , l, , l, , flyash, CO2, C, nitrogen oxides, sulphur, oxides)., –, Metallurgical processing (mineral dust, fumes, containing fluorides, sulphides and metallic, pollutants like lead, chromium, nickel,, beryllium, arsenic, vanadium, cadmium, zinc,, mercury)., –, Chemical industries including pesticides,, fertilizers, weedicides, fungicides., –, Cosmetics., –, Processing industries like cotton textiles,, wheat flour mills, asbestos., –, Welding, stone crushing, gem grinding., The air pollutants have been classified into two, categories as primary air pollutants or primary, emissions and the secondary air pollutants., Primary emissions or pollutants include those, substances which are emitted directly from some, identifiable sources. These include – sulphur, compounds; carbon compounds [includes oxides, of carbon (CO, CO2) and hydrocarbons]; nitrogen, compounds (includes NO2 and NH3); halogen, compounds [includes hydrogen fluoride (HF) and, hydrochloric acid (HCl)]; particles of different size, and different substances are found suspended in, air., The oxides of sulphur, carbon, nitrogen,, hydrocarbons, photochemical oxidants and, fluorides are the common gaseous pollutants., Carbon monoxide (accounts for 50% of, atmospheric pollution) is the most poisonous gas, and is released from motor vehicles and industries., Carbon monoxide is harmful to man as it competes, with O 2 for haemoglobin and form, carboxyhaemoglobin., When a man inhales air containing normal, concentration of O2 and also carbon monoxide, he, suffers from suffocation because haemoglobin, combines with CO instead of O2 and the product, formed cannot dissociate., CO poisoning can lead to giddiness, laziness,, exhaustion, reduced vision, nervous and, cardiovascular disorder and even death., The CO2 increase in the air may cause rise in, atmospheric temperature which may melt the polar, ice, causing rise in ocean level and consequent, flooding of towns., Nitrogen oxide form about 10% of pollutants., , l, , l, l, , l, l, , l, l, l, l, , l, , l, , l, , l, , 563, , Oxides of nitrogen causes eye irritation,, respiratory troubles, lung oedema, blood, congestion and dilation of arteries. Nitrogen, monoxides like CO, lowers the oxygen carrying, capacity of the blood., Oxides of sulphur (sulphur dioxide and sulphur, trioxide) form about 18% of total air pollutants., They may cause respiratory diseases (asthma,, bronchitis, emphysema) and eczema in man. The, exhausts from Mathura Refinery are a threat to the, Taj at Agra., Burning of fossil fuels is the main cause of, sulphur dioxide pollution., SO2 and its transformation products in atmosphere, on plant cell causes membrane damage, plasmolysis,, chlorophyll destruction, metabolic inhibition,, growth and yield reduction., SO2 causes chlorosis, necrosis of vegetation, metabolic inhibition and growth reduction., The compounds of SO2 have mutagenic effects., Acid rain is mainly due to pollution of sulphur, dioxide (combined with water forming sulphuric acid)., Acid rain (term coined by Robert August in 1872), is rainfall and other forms of precipitation with a, pH of less than 5. (pH of normal rain is 5.6–6.5)., There are two types of acid deposition : wet, deposition and dry deposition. Wet deposition is, acidic water received through rain, fog and snow, while dry deposition is wind blown acidic gases, and particles in the atmosphere., Approx. half of the natural forest have been, destroyed by acid rain in Europe and NE United, States., Problems and impacts of acid rain are –, –, Soil acidity – affect land flora and fauna., –, Acidification of lakes and streams – affect, aquatic life, crop productivity, human., –, Corrodes buildings, monuments and statues, made of lime stones, bridges, fences, railings etc., In Greece and Italy, invaluable stone statues have, been partially dissolved and the Tajmahal in India, is affected by the acid rain., The nitrogen oxides by producing peroxy, acylnitrates, photochemical smog affects human, health and plant vegetation., Flourides causes leaf chlorosis, necrosis of, margins, tips and abscission of leaves,, fruits etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 564, , l, l, , l, , l, l, , l, , l, l, l, l, l, , l, l, l, l, l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Hydrogen flourides causes flourosis., Phosgene and methyl isocyanate were responsible, for the Bhopal gas tragedy that took place in, 1984 in India., Lead is a pollutant from automobile exhausts which, affects health adversely and causes, mental illness., Lead is believed to be responsible for the fall of, the Roman Empire., Hydrocarbons or volatile organic compounds are, formed naturally by incomplete combustion of, fuel in automobiles., Marsh gas or methane is produced during, decomposition of organic matter, paddy fields and, due to incomplete combustion in automobiles and, industries., Many hydrocarbons are carcinogenic. They also, cause irritation of eyes and bronchial constriction., Garden pea is SO2 pollution indicator., Lichens are grown as pollution indicator., Maize indicates flouride pollution., Particulate matter (PM) are air borne matters, which results not only from direct emission of, particles but also from emissions of some gases, that condense as particles directly or undergo, transformation to form particles., PM consists of soot, flyash, dusts of various types,, fur, hair, spores, pollen grains etc., Fine particles of ash present in fuel gas are called, fly ash. It is expelled from thermal power plants., Fly ash block the stomata and also reduces the, absorption of light energy by plants., Fly ash is absent in automobile exhausts., Particulate matter from processing industries, eg., cotton dust, iron mill dust, mine dust, flour mill, dust, gem grinding causes pneumoconiosis,, byssinosis, emphysema, siderosis and other, pulmonary problems (iron deposition in tissues)., Particulate matter can be settleable and suspended., Suspended PM can be further differentiated as, aerosol (less than 1 mm), dust (solid, more than, 1 mm) and mist (liquid, more than 1 mm)., Smoke causes about 10 – 15% of atmospheric, pollution., Most of the components of smoke are similar to, those present in automobile exhausts like sulphur, dioxide, sulphites, 34benzpyrene (causing lung, cancer) and oxides of nitrogen., Soot, lead particles from exhaust, asbestos, flyash,, , l, , l, , l, , l, l, l, , l, l, , l, , l, , l, , l, , l, , l, , l, , volcanic emission, pesticides, H2SO4, mist, metallic, dust, cotton, cement dust etc. when inhaled by man, cause respiratory diseases such as tuberculosis,, cancer and byssinosis (due to cotton dust)., Different bacterial cells, spores, fungal spores,, pollen grains can create bronchial disorders, allergy, and many other diseases in animals and plants., Secondary air pollutants are usually produced, photochemically from primary pollutants and are, called photochemical oxidants., Photochemical oxidants includes peroxyacyl, nitrate (PAN), ozone and aldehydes.These are, formed by the reaction of nitrogen oxide with the, hydrocarbons present in the air., Secondary pollutants are photochemical smog and, acid rain., The fog deposited with smoke and chemical fumes, forms a dark and thick covering, the smog., Smog is very common in almost all the industrial, areas and the cities situated in the basin experience, it more because there the smog is trapped for many, days by the stagnant air., Smog is of two types classical (London) smog, and photochemical (Los Angeles) smog., Classical smog, occurs at low temperature, contains, sulphur gases (hydrogen sulphide, sulphur dioxide),, smoke & dust particles., It is formed by condensation of water vapours with, H2S & SO2 over dust & smoke particles. In them, secondary pollutants are absent., It occurred in London during December 1952 when, it affected 50% of population & killed over 4000, persons., Photochemical or Los angeles smog, having, oxidizing environment, contains secondary, pollutants., It is formed at high temperature due to still air,, emission of nitrogen oxides & carbohydrates from, automobile exhausts & solar energy., The principal photochemical products are olefins,, aldehydes, ozone (described later), PAN, (peroxyacyl nitrate), PBzN and photochemical, smog., PAN is produced due to reaction between oxides, of nitrogen and hydrocarbons under effect of, ultra violet radiation of sunlight, when O3 is also, formed., There are three techniques for control of gaseous, pollutants – combustion, absorption and, adsorption method.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐńńśŚĽŐň– ·– ◙ńŐĐďń– ◄ňŢĽŕŐňŇĚňŚďń– ►ĺďňĹĚř–, l, , l, l, , l, , In combustion process, oxidisable gaseous, pollutants are completely burnt at a high, temperature., In absorption technique, gaseous pollutants are, absorbed in suitable absorbent materials., Adsorption technique is applied to control toxic, gases, vapours and inflammable compounds that, could not be efficiently removed or transferred by, the aforesaid technique., According to sizes of air pollutants range and types, of chemicals, different suitable devices are effective., Some new devices are most widely used as settling, chambers, cyclone collector, bag filters, wet, collectors, electrostatic precipitators (ESP, most, effective device), gas scrubbers, catalytic, combustion, incineration etc., , –, , l, l, , WATER POLLUTION, l, , l, , l, l, , l, , l, , Water pollution is the deterioration of the quality, of water due to addition of foreign substances,, factors (heat) and deprivation that makes it health, hazard, unfit for human use and aquatic organisms., Water pollutants may be of three types –, biological (viruses, bacteria, protozoa etc);, chemical (organic wastes, organic biocides,, inorganic chemicals); and physical (hot water, oil, spills etc)., Water pollution has two major sources – natural, and anthropogenic., Natural sources of water pollution includes clay, and slit from soil erosion, leaching of minerals,, falling of organic matter from the banks., Anthropogenic or manmade sources of water, pollution are domestic waste, sewage, soaps and, detergents, runoff from agricultural fields having, fertilizers and pesticides, industrial wastes, heat,, waste from animal sheds and slaughter houses, oil, pollution, etc., Sources of water pollution are –, –, Industrial discharge of chemical wastes and, byproducts, –, Discharge of poorlytreated or untreated sewage, –, Surface runoff containing pesticides, –, Slash and burn farming practice, which is often, an element within shifting cultivation, agricultural systems, –, Surface runoff containing spilled petroleum, products, , l, , l, , l, , l, l, l, , 565, , Surface runoff from construction sites, farms,, or paved and other impervious surfaces, e.g., silt, –, Discharge of contaminated and/or heated water, used for industrial processes, –, Acid rain caused by industrial discharge of, sulphur dioxide (by burning highsulphur, fossil fuels)., –, Excess nutrients added by runoff containing, detergents or fertilizers, –, Underground storage tank leakage, leading to, soil contamination, hence aquifer, contamination., Water pollutants may be organic or inorganic type., Some organic water pollutants are –, –, Insecticides and herbicides, a huge range of, organohalide and other chemicals, –, Bacteria, from sewage or livestock operations, –, Food processing waste, including pathogens, –, Tree and bush debris from logging operations, –, VOCs (Volatile Organic Compounds,, industrial solvents) from improper storage., Some inorganic water pollutants include –, –, Heavy metals including acid mine drainage, –, Acidity caused by industrial discharges, (especially sulphur dioxide from power plants), –, Chemical waste as industrial byproducts, –, Fertilizers, in runoff from agriculture including, nitrates and phosphates, –, Silt in surface runoff from construction sites,, logging, slash and burn practices or land, clearing sites., Organic matter in water provides nutrition for, decomposers such as bacteria and fungi. They, breakdown the organic matter using oxygen and, deficiency of oxygen kills fishes and other aquatic, animals., BOD (biological oxygen demand) is the amount of, dissolved oxygen required by bacteria in, decomposing the organic wastes of water. Higher, the BOD, lower would be the dissolved oxygen., When large amount of sewage is dumped into water,, the BOD will increase., Pure drinking water should have BOD of less than, 1 ppm., Chemical oxygen demand (COD) test is aimed to, determine the amount of oxygen needed to oxidise, all pollution materials.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 566, , l, l, , l, l, , l, , l, l, l, , l, l, , l, l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The value of COD is much higher than BOD., Many pesticides such as chlorinated hydrocarbons,, organophosphates, organochlorine compound etc, are nonbiodegradable and their residues have long, life. They enter the food chain and accumulates, mostly in fatty acids., Detergents are regarded as major pollutant in, surface water., Phosphorous and nitrates of fertilizers and, detergents dissolve in water and accelerate growth, of algae which form mat on the water surface., The algal growth deoxygenate water which are, responsible for death of fishes and other aquatic, animals., The increased productivity of lake and pond etc., due to nutrient enrichment is called eutrophication., Eutrophication causes reduction in dissolved, oxygen., Industrial wastes such as cadmium, arsenic,, mercury, lead, zinc etc. when released into water, may reach the human body with contaminated food, etc., which are very harmful for the health., The metals concentrate through the food chain to, levels that result in heavy metal poisoning., Main sources of mercury pollution are combustion, of impure coal, smelting of metallic ore, paper and, paint industries., Concentration of toxic material increases at every, trophic level. This is known as biomagnification., Radioactive waste from atomic power plants are, stored in underground tanks. Radioactive materials, reaches to crops, livestocks, and man through food, chain., Faecal pollution is indicated by number of, Escherichia coli in water., Warmer water has less oxygen (14 ppm at 0°C,, 1 ppm at 20°C), so thermal pollution causes, deoxygenation of water bodies which decreases the, decomposition of organic wastes and kills the, aquatic animals., Phosphate pollution is caused by sewage and, agricultural fertilizers., Polluted water affect the health and economy of, man as well as other living organisms. Pollutants, make water unfit for domestic and industrial use., Taking fishes and other eatable aquatic animals, poisoned with methyl mercury causes deformity, called minimata disease., , l, , l, , l, , l, , l, , l, l, , Itaiitai disease (in Japan) is caused due to, accumulation of cadmium, characterized by pain, in joints and bones ., In bluebaby syndrome excess nitrate reacts with, haemoglobin and forms nonfunctional, methaemoglobin in infants. It impairs oxygen, transport., Contamination of drinking water with arsenic, causes black foot disease. It is characterized by, diarrhoea., Excess use of fluoride tooth paste may lead to, skeletal fluorosis or knock knee disease in which, joints and bones become stiff and hard., Polluted water are treated in Effluent Treatment, Plant before their release into water bodies. There, are three steps in sewage treatment –, –, Primary treatment Physical treatments such, as sedimentation, floatation, fragmentation and, filteration are involved in primary treatment., –, Secondary treatment There are two ways, in secondary treatment : anoxic (it is through, the action of anoxic micro organisms and, macromolecules) and aerobic (it is by two, ways : trickling filter method and activated, sludge method)., –, Tertiary treatment Removal of nitrates and, phosphates takes place in this step., Sewage water treatment is very expensive that is why, only first two steps are followed in many countries., Treatment of industrial effluents involves, neutralization of acids and bases, precipitation of, metallic compounds, chemical oxidation etc., , SOIL POLLUTION, l, , l, , l, l, l, , Soil pollution, also called land pollution is addition, or removal of nutrients which reduces the, productivity of soil., The substances which are responsible for the, reduction of soil productivity is called as soil, pollutants., Soil pollutant alters the basic composition of the, soil that may kill important soil organisms., Pesticides, fertilizers, chemicals and radioactive, wastes etc. are the main sources of soil pollution., Various metals such as lead, tin, copper, cadmium, etc., insecticides such as BHC, DDT, aldrin,, melathion, fungicides, weedicides and many, fertilizers are responsible for soil pollution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐńńśŚĽŐň– ·– ◙ńŐĐďń– ◄ňŢĽŕŐňŇĚňŚďń– ►ĺďňĹĚř–, l, , l, l, l, l, , l, , l, , l, , Quality of land also deteriorate due to, deforestation, desertification, water logging,, flooding., There are two types of soil pollution : positive and, negative soil pollution., When there is addition of undesirable substance, in the soil then it is called as positive pollution., When there is reduction of soil fertility due to loss, of its top layer, it is called as negative pollution., Negative pollution is also, sometimes, called third, pollution or landscape pollution in which fertile, land is converted into barren areas by addition of, solid wastes like leather good, spoiled food items etc., Soil pollution can be checked by improving the, disposal wastes, appropriate use of chemical, fertilizers and use of biological pest control ., The most important measure to check land, degradation is restoration of forest, crop, rotation, improved drainage etc., There are two types of wasteland : unculturable, and culturable. Rocky area, snowcovered area,, steep slopes are unculturable area. Waterlogged, land, marshy area, forest land etc. are the example, of culturable land area., , RADIOACTIVE POLLUTION, l, l, l, , l, , l, , l, , l, , l, l, , Pollution of air, water and soil with radioactive, materials is called as radioactive pollution., Radioactive pollution may be natural or manmade., Cosmic rays which reaches the earth, radiation from, radioactive material present in rocks, soil etc. are, natural radiation., Atomic explosion, atomic reactors and nuclear fuel,, mining and refining of plutonium and thorium etc., are manmade radiation., Radioactive pollution affects all the organisms, including humans. It causes cancer, mutations and, even death in humans and animals., Radioactive wastes from various atomic reactors, should be changed into harmless form before, disposing off., Leakage of radioactive material from nuclear, reactors should be prevented. Atomic explosion and, use of atomic weapons should be banned., Radioactive pollution is not curable, hence it must, be checked., Radioactive substances that are carried to distant, places by wind and fall on the ground alongwith, rain water is called nuclear fall out., , l, l, l, l, , l, , l, , l, l, , l, , l, , l, , l, l, l, , 567, , Wastes from atomic power plants come in the form, of spent fuels of uranium and plutonium., In India, there are 4 atomic power plants : Narora,, Tarapur, Kalpakkam, and Rawat Bhata., Many radioactive isotopes like C14, I125, P32, O18 and, their compounds are used in scientific researches., On the basis of their action on cells, radiations are, divided into two categories – nonionising, radiations & ionising radiations., Nonionising radiations include ultraviolet rays, (100–300 nm) which are known to cause sunburn,, snow blindness, inactivation of organic bio, molecules formation of thyminedimer in DNA,, and skin cancer., Ionising radiations include Xrays, cosmic rays, and atomic radiations which damage the living, cells by ionisation (shifting the electrons from, one to other biomolecule)., High altitude plants have polyploidy as a protective, mechanism against radiations., Actively growing and dividing cells like those of, stratum germinativum, intestinal lining, bone, marrow, gonads and embryo (with all cells rapidly, growing and dividing) are more susceptible to, ionising radiations., Less active and nondividing cells like osteocytes, of bones, muscles fibres and neurons are not so, easily damaged by radiations., Strontium90 accumulates in the bones to cause, bone cancer and tissue degeneration in a number, of organs., Iodine131 damages WBCs, bone marrow, spleen,, lymph nodes, skin cancer, sterility and defective, eye sight., Radioactive iodine may also cause cancer of, thyroid glands., Cesium137 brings about nervous, muscular and, genetic changes., Uranium causes skin cancers and tumors in the miners., , NOISE POLLUTION, l, , l, , Unpleasent loud sound is called as noise (also, called slow killer) and disturbing level of noise, is known as noise pollution., Annoying noise from industries, transport vehicles,, agricultural machines, defence equipments,, domestic gadgets, music systems, public address, systems and demonstrations are various causes of, noise pollution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 568, , l, l, l, , l, l, , l, l, , l, l, l, , l, l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Noise pollution is measured in decibels., A sound more than 115 db is harmful to the ears., Moderate conversation has a noise value of 60 dB;, scooter, buses, trucks, etc. create noise of about, 90 dB; jets of about 150 dB and rockets of 180 dB., A decibel value above tolerable limit of noise is, about 140 dB., Noise pollution can cause damage to heart, increase, blood cholesterol and even raise blood pressure, and is also responsible for stomach disorders, (ulcers), reduced hormonal secretions and change, in the renal functions., Noise also causes anxiety and stress, increased rate, of heart beat, headache by dilating blood vessels etc., A constant exposure to noise of 130 dB, (explosions) may lead to partial or complete, deafening of the ears., A regular exposure to sound of 80 dB reduces, hearing by 15 dB in 10 years., Noise become uncomfortable above 100 dB., Noise stimulates the secretion of adrenaline which, increases irritability, nervousness, neuromuscular, tension and feeling of fatigue, so decreasing the, working efficiency., Noise causes vasoconstriction which decreases the, blood flow., Average street noise level in the metropolitan cities, like Mumbai, New Delhi and Calcutta is above 95 dB., Mumbai considered to be the third noisest city in, the world. Some areas in Mumbai have recorded, as high as 105 dB of noise., Reduction of noise level from the source, check, of noise transmission, and protection of human, beings from noise are the three main measures, to control noise pollution., Green muffler scheme involves the growing green, plants along roadsides to reduce noise pollution., , GLOBAL ENVIRONMENTAL CHANGES, l, , l, l, , The atmospheric green house gases forms a blanket, like covering around the earth. It controls the escape, of heat from the earth's surface to outer space and, keep it warm and hostile. This phenomenon is, known as green house effect., The capacity of atmosphere to keep the earth warm, depends on the amount of green house gases., The greenhouse effect is a phenomenon whereby, increased carbon dioxide emissions create a, condition in the upper atmosphere, causing a, , l, , l, , l, , l, l, , l, , trapping of excess heat and leading to increased, surface temperatures., The major natural greenhouse gases are – carbon, dioxide (60%), methane (20%), nitrous oxide (6%), and chlorofluorocarbons (14%). Also of minor, significance are water vapour and ozone., The major atmospheric constituents (N2 and O2), are not greenhouse gases, because homonuclear, diatomic molecules (e.g. N2, O2, H2) neither absorbs, nor emit infrared radiation as there is no net change, in the dipole moment of these molecules., When concentration of green house gases increase, in the atmosphere, it retains more and more infrared, radiation, resulting in enhanced green house effect., Due to enhanced green house effect, there is increase, in global mean temperature or global warming., Carbon dioxide, methane, chlorofluorocarbon and, nitrous oxide are radioactive gases which absorbs, long wave infrared radiations., Global warming has many fold effects as –, Table : Important legislations for the protection, of environment., Function, Name of Act, Law meant for the, 1. The Environment, Protection Act, 1986 protection of air, water,, soil and noise., 2. The Insecticide Act, Power of government to, regulate the import,, 1968, manufacture,, sale,, distribution and use of, insecticides., 3. The Water (prevention Deals with preservation, and, control, of and quality control of, water pollution., pollution) Act, 1974, 4. The Air (prevention and Deals with preservation, control of pollution) and control of air, pollution., Act, 1981, , –, , –, –, , Effect on weather and climate There is, increase in average temperature by 1.45.8, degree centigrade by the year 2100. Warming, of atmosphere increases its moisture, containing capacity. All these are responsible, for change in precipitation pattern. This, climatic change is harmful for human health., Sea level change The global warming is, responsible for increase in sea level and, melting of glaciers and green land ice sheets., Effects on range of species distribution
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ŐńńśŚĽŐň– ·– ◙ńŐĐďń– ◄ňŢĽŕŐňŇĚňŚďń– ►ĺďňĹĚř, , l, , l, , l, , l, , l, , l, , l, , l, , l, , Due to increase in global warming, many, species are expected to shift poleward or, towards high elevation in mountain regions., –, Food production Increase in temperature, causes extensive growth of weeds which, ultimately decrease crop production., Some strategies should be followed to deal with, global warming –, –, Vegetation cover should be increased for, photosynthetic utilization of carbon dioxide., –, Chlorofluorocarbon should be replaced with, some other substitute having little effect on, global warming., –, Reducing the use of nitrogen fertilizers to, reduce nitrous oxide emission., –, Minimizing the use of fossil fuel to reduce, the green house gas emission., Stratosphere have a thick layer of ozone which, protects life on earth from harmful effects of, UV radiations., Ozone in the Earth’s atmosphere is generally, created by ultraviolet light striking oxygen, molecules, which consist of two oxygen atoms (O2),, creating two single oxygen atoms, known as atomic, oxygen. The atomic oxygen then combines with a, molecule of O2 to create ozone, O3., Ozone absorbs most of the ultraviolet radiation, so, it shields earth against biologically harmful solar, radiations., Ozone depletionrefers to the phenomenon of reduction, in the amount of ozone in the stratosphere.The depletion, of O3 layer by human activities may have serious, implications and this has become a subject of much, concern over the last few years., Ozone layer depletion has various negative effects, on atmosphere. UV radiation increases more on, earth. In humans it causes skin cancer, cataract,, reducing the functioning of immune system. UV, radiation inhibits photosynthesis in phytoplanktons., Chloroflourocarbons or CFCs (CCl2F2 and CCl3F;, used as coolants in air conditioners and refrigerators,, cleaning solvents, aerosol propellants and foam, insulation), nitrogen oxides (coming from fertilisers), and hydrocarbons are responsible for O3 depletion., CFC produces active chlorine in the presence of, UV radiation. These destroy ozone, converting it, into oxygen., Nitrogen dioxide is a pungent gas; it produces a, , Ø, , Ø, , Ø, , Ø, , Ø, Ø, , Ø, , l, l, l, l, , l, l, , l, l, , 569, , Montreal Protocol : A landmark international, agreement to protect the stratospheric ozone by, agreeing to limit the production and use of ozone, depleting substances phasing out ozone depleting, substances & helping the developing countries to, implement use of alternatives to CFCs., Helsinki Declaration (May, 1989) : Montreal, Protocol was ratified by 82 nations at Helsinki., They pledged to phase out CFCs by 2000., In June 1990, 93 nations amended Montreal, Protocol and Helsinki Declaration. They agreed, to phase out CFCs and other ODS by the end of, 20th century., Intergovernmental Panel on Climate Changes, (IPCC, 1988) : Prepared a world climatic, programme (WCP)., Convention on Climate Change (CCC) Under, UN framework in 1991., Earth Summit (United Nations Conference on, Environment and Development, 1992). It was, held in RiodeJaneiro (Brazil) and adopted the, recommendations of CCC for reducing, greenhouse gases. The recommendations were, signed by 154 nations. They pledged to maintain, emission of green house gases at 1990 level., Kyoto Protocol : International conference held, in Kyoto, Japan (during December 1997), obtained commitments from different countries, for reducing overall greenhouse gas emissions, at a level 5% below 1990 level by 20082012., , brownish haze, causes nose and eye irritations and, pulmonary discomfort., Major aerosol pollutant present in jet plane, emissions is fluorocarbon., The ozone layer is destroyed by aerosols., Aerosols are certain chemicals released into the air, with force in the form of mist or vapour., The thickness of ozone shield is declining gradually., This is called as ozone hole (First discovered in, 1985 over Antarctica)., Dobson is an unit of ozone hole amount., UV radiation is nonionizing type and it is lethal, due to inactivation of proteins, pigments and, nucleic acids., Carotenoid pigments prevent the damage of plant, cells from ultraviolet rays., The molecular action of ultraviolet rays is mainly, reflected through destruction of hydrogen bonds, between DNA strands.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 570, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 63, , Wild Life & Conservation, l, , l, l, , l, , l, , l, l, , l, , l, , l, , l, l, , Wildlife includes animals, plants and micro, organisms in their natural habitat like grassland, forest, desert etc., William Hornady (in 1913) coined the term wild, life in his book “Our Vanishing Wild Life”, Wildlife is important because it balances, population, maintains food chains, natural, cycles, biodiversity, control pollution, prevent, soil erosion and it is the source of gene bank., Reasons behind the depletion of wildlife are large, scale destruction of habitat, poaching, hunting,, change of migratory route, introduction of exotic, species and exploitation of natural products, etc., Exotic species or species introduced from outside, produce ecological imbalance due to removal of, biological control., Ecological diversity occurs due to the presence of, large number of species in a community or area., Because of the presence of high degree of variability, in the gene pool and occurrence of a large number, of varieties, biotypes and cotypes, genetic diversity, occurs., The species which is found in a particular natural, habitat beyond which it is unknown, is called, endemic species, e.g., Ficus religiosa., Exotic species are those species which are not, native to an ecosystem, but often established, purposefully or inadvertently by human activity., Hunting are of three types sport hunting (for, recreation), subsistence hunting (for safety and, food) and commercial hunting (for food)., A species of wild life likely to disappear from the, world sooner or later is called threatened species., For conservation of wild life, the threatened, species have been classified as ‘endangered’,, ‘vulnerable’ and ‘rare’ according to the degree, of danger they face for survival., , l, , l, , l, , l, , l, l, , Rare species are species with small populations, either restricted geographically with localised, habitats or with widely scattered individuals. These, species are at risk of becoming more rare, but they, are not in immediate danger of extinction., Vulnerable species are species under threat of or, have actually declining number, or which have been, seriously depleted in the past and have not yet, recovered., Endangered one are species with low population, numbers that are in considerable danger of, becoming extinct., Critically endangered species are those that are, facing very high risk of extinction in the world and, can become extinct any moment in immediate future., Indeterminate species are in danger of extinction, but the reason is unknown., Red data book are directories and scheme compiled, Table : Some important abbreviations., UNESCO, MAB, , –, , IUCN, , –, , WWFN, IBP, ZSI, BSI, BNHS, , –, –, –, –, –, , IBWL, CITES, , –, –, , –, United Nations Educational,, Scientific and Cultural Organization, Man and Biosphere programme, (1971), International Union for the, conservation of Nature and Natural, resources (1948), Switzerland, World Wide Fund for Nature (1961), International Biological Programme, Zoological Survey of India, Botanical Survey of India, Bombay Natural History Society,, Bombay (1883), Indian Board for Wild Life (1952), Convention on International Trade, in Endangered Species of wild flora, and fauna (1976).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ♣Ľńę– ▌ĽěĚ– ·– ►ŐňřĚŕŢďŚŐň, , l, , l, , l, , l, , l, l, l, , l, l, , l, l, l, l, l, , l, , l, , by IUCN providing upto data informations of all, endangered animals and plants., Red data book has pink pages for critically, endangered species. As soon as a species recovers, it is deleted from the pink page and entered on, green page., Threatened species is liable to become extinct if, not allowed to realise full biotic potential by, providing protection from exotic species/human, exploitation / habitat deterioration/depletion of, food., The number of critically endangered animals and, plants in India is 18 and 44 respectively, eg Sus, salvanius, Berberis nilghiriensis., In India endangered animals are Ailurus fulgens, (Red Panda), Bentinckia nicobarica, Blue whale,, Asiatic wild Ass etc., Addax antelope is vulnerable species and its number, continue to decline., Great Indian Bustard (Ardeotis nigriceps) is a, rare species of birds found in India., The number of threatened plants is 474 while that, of animals is over 100, e.g., Newcomb’s snail,, goldenlion, tamarin etc., The rhinoceros, sloth bear, tiger, wild ass are, some endangered animals of India., Vulnerable species are likely to move into the, endangered category in near future if the casual, factors continue to operate., Snow leopard (Leo uncia) was listed as, indeterminate species., Wildlife Institute of India is located at Dehradun, (U.P.) ., Indian Institute of Forest Management is, situated at Bhopal., Hoolock gibbon is the only ape in India., The process in which careful exploitation,, protection and management of our natural resources, is carried out and the process by which these natural, resources are protected from destructive influence,, misuse and decay are together known as, conservation (Odum 1972.), Various methods by which wild life can be, conserved are enactment of wild life laws, species, preservation, assemblage protection, habitat, preservation, mass education etc., Important steps for conservation of wild life are :, (i) protection of life in natural as well as artificial, , l, l, , l, , l, , l, , l, l, l, l, , l, , l, , 571, , habitats, (ii) preference for threatened species over, others in conservation prog ramme, (iii), maintenance of lifesupporting systems (air,, water and land), (iv) safeguarding of critical, habitats, (v) preservation of the ecosystem rather, than a single species, (vi) discouraging the over, exploitation of species of ecosystem, (vii) stopping, trade of rare species, (viii) protection of migratory, animals by intern ational agreements, (ix), integration of national conservation programmes, with international ones, and (x) setting up of, national parks and sanctuaries., Conservation are categorized into insitu and ex, situ., In situ conservation is the protection and, management of important components of biological, diversity through a network of protected areas., Protected areas are ecological/biogeographical, areas where biological diversity alongwith natural, or cultural resources is protected, maintained and, ma nag ed throug h lega l or other effective, measures., In situ conservation is being undertaken by national, parks, wildlife sanctuaries and biosphere, reserves. It is being conducted by Ministry of, Environment and Forests. Joint Forest Management, (JFM) is practised in 10.25 million hectares of, degraded forests through 36075 village forest, protection committees., National parks are reserves of land, usually owned, by governments, that are protected from most human, development and pollution., Cultivation, grazing, forestry and habitat, manipulation are not allowed in the national parks., The idea of national park was first formulated by, painter George Catlin., The World’s first national park is Yellow stone, national park., The first National Park in India was set up in, 1935 in the foot hills of Himalayas in Uttar Pradesh, and was known as Hailey National Park. It is now, known as (after the famous wild life lover) Corbett, National Park., National parks are large areas as scenic & national, beauty maintained for scientific, educational &, recreational area., Dachigam National Park is famous for Hangul, (Kashmiri stag).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 572, , l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Indian rhinoceros is the most important, protected species in Kaziranga National Park., Orang National Park (Assam) is one of India’s, youngest national park and home of the World’s, third largest population of the one horned, rhinoceros. It covers only 78.8 sq. km area., Sanctuaries are tract of land with or without lake, where wild animals or fauna can take shelter without, being hunted., Keoladeo Ghana National Park, popularly, known as Bharatpur is India’a best known bird, sanctuary., The Bharatpur Bird Sanctuary known as largest, bird sanctuary in Asia, which is much more, famous as a refuge of migratory birds, like barons,, ibis, pelicans and painted storks that make it their, temporary home during the winter months., Two splendid protected habitats situated in the, Himalayan foothills are the Corbett National, Park and the Dudhwa National Park that provide, an unforgettable wildlife experience., Ashoka was the first ruler in recorded history to, order the establishment of wild life sanctuaries., Project tiger was started in 1973. Its aim is to, create reserves in selected areas of India to increase, the tiger population., Number of national parks and sanctuaries, selected for ‘Project Tiger’ as per latest, information are 18., The famous tiger reserves in India are Corbett, and Dudhwa in U.P., Kanha and Indravati in, M.P., Simplipal in Orissa etc., The largest tiger reserve in India is Nagarjuna, sagar, Hyderabad., The concept of biosphere reserve was evolved in, 1986 by MAB (Man and Biosphere) programme, of UNESCO., Biosphere reserves are multipurpose protected, areas which are meant for preserving genetic, diversity in representative ecosystem by, protecting wild population, traditional life style, of tribals and domesticated plant and animal, genetic resources., A biosphere reserve is basically divided into the, following zones core zones (no human activity, is allowed), buffer zone ( limited human activity, is allowed), manipulative zone (where human, activity is allowed but ecology is not permitted to, , l, l, l, l, , l, l, l, l, l, , l, l, l, l, l, l, l, l, l, , l, , l, , 3rd October is known as World animal day., 29th December is known as biological diversity, Day., 5th June is World environment day., Wild life week is first week of October., , be disturbed) and restoration zone (degraded area, for restoration to near natural form)., First biosphere reserve in India was set up in, 1986 in Nilgiri., There are about 243 biosphere reserves in 65, countries of the world., Salim Ali Centre for Ornithology and Natural, History is situated at Coimbatore., Asian lion is only found in Gir forest of Gujarat., Siberian crane is most peculiar winter visitor, of Ghana bird sanctuary. In this sanctuary, saurus, crane is renowned for its breathtaking courtship, dance., Golden Langur is found in the jungles of Assam, state., Autobiography of Dr. Salim Ali is “Father of a, Sparrow”., Fastest animal of the world is Cheetah. Its speed, is 79 to 115 km per hour., Largest living bird is African Ostrich., Fastest flying bird is the swift. Flying speed is, 171 km per hour., Bird that flies at maximum height is Barheaded, Due that can fly at a height of 20,000 meters., “The old man of the jungle” is used for, Orangutan., Animal with maximum height is Giraffe., There have been about 83 national parks and 21, sanctuaries with a total area of about 1, 41, 298, sq.Km., Few protected Indian wild life are – Himalayan, newt (Tylototriton verrucous), Gharial (Gavialis, gangeticus), Leathery turtle (Dermochelys, coriacea), Python (Python molurus), Great Indian, bustard (Choriotis nigriceps), Great Indian hornbill, (Buceros bicornis), Large falcons (Falco, peregrinus), Siberian white crane (Grus, leucogeranus), Black buck (Antelope cervicapra),, Chital (Axis axis), Gangetic dolphin (Platanista, gangetica), Golden langur (Presbytis geci)., Gahirmatha marine sanctuary in Orissa is the, conservation breeding site for turtles.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 573, , ♣Ľńę– ▌ĽěĚ– ·– ►ŐňřĚŕŢďŚŐň, , Some country symbols based on animals are, India Tiger, Australia Kangaroo, China Giant, panda, USA Bald eagle, RussiaWhite bear etc., The first recorded bird that is now no more was, Dodo of Mauritius., The number of vertebrate species facing extinction, is 1000., Famous snake garden of India is situated in, Madras., Flamingoes are protected in Chilka lake,, Orissa., ś›ģ ‡π•…ģ ˘“‚‡˚†‰ˇ•π“‚ is the conservation outside, their (organism) habitats by perpetuating sample, populations in genetic resources centres, zoos,, botanical gardens etc., Ex situ conservation includes offsite collection and, gene banks., Offsite collection are live collections of wild and, domesticated species in botanical gardens, zoos,, arboreta etc., Gene banks are institutes that maintain stocks of, viable seed (seed banks), live growing plants, (orchards), tissue culture and frozen germplasm, with the whole range of genetic variability., Seeds are of two types – orthodox and recalcitrant., Orthodox seeds can tolerate reduction in moisture, content (upto 5%), anaerobic conditions and low, temperature of –10º to –20ºC or even lower for, prolonged periods, e.g., cereals, legumes., Recalcitrant seeds are those seeds which get killed, on reduction of moisture and exposure to low, temperature, eg., tea, cocoa, jackfruit, coconut. They, , l, , l, l, l, l, lģ, , l, l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , can be stored for shorter duration after treatment, with fungi in rooms having humid air and normal, oxygen., Plants with recalcitrant seeds are grown in orchards, where all possible strains and varieties are, maintained, e.g., litchi, oil palm, rubber tree, etc., Tissue culture is carried out through callus, formation, embryoids, pollen grain culture and, shoot tip culture for those plants which are either, seedless, have recalcitrant seeds, variable seed, progeny or where clone is to be maintained., This method is useful in maintaining a large, number of genotypes in small area, rapid, multiplication of even endangered species and, for hybrid rescue., Shoot tip culture maintains virus free plants. It, is used for international exchange of germplasm, in vegetatively multiplied cultivars, e.g., banana,, potato., Cryopreservation is preservation at –196ºC (liquid, nitrogen) and which can maintain tissue culture,, embryos, animal cells/tissues, spermatozoa, indefinitely. The cryopreserved material is revived, through special technique when required., Major ex situ conservation of biodiversity is being, managed by National Bureau of Plant, Animal, and Fish Genetic Resources. There is an, International Crop research Institute for SemiArid, Tropics (ICRISAT) in Hyderabad for conserving, germplasm of groundnut, pigeon pea, chick pea,, pearl millet and sorghum., , Table : Important protected wildlife and associated protected areas., Protected animal, , Protected area/areas, , 1., , Panthera leo (Lion), , Gir National Park, Junagarh (Gujarat)., , 2., , P. tigris (Tiger), , 18 National parks/sanctuaries under “Tiger Project”, e.g. Corbett National Park (Uttranchal),, Hazaribagh Sanctuary (Bihar), Sunderbans Tiger, Reserve (W. Bengal), Ranthambore N. Park, (Rajasthan), etc., , 3., , Rhinoceros unicornis (Rhino), , Kaziranga National Park (Assam), , 4., , Moschus mosciferus (Musk deer), , Shikari Devi Sanctuary (H.P.), , 5., , Choriotis nigriceps (Great Indian Bustard), , Desert National Park (Rajasthan), , 6., , Cervus elephus hanglu (Kashmiri stag), , Dachigam National Park/Sanctuary (J&K).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 576, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Biosphere reserves of India, Biosphere Reserve, , State(s), , 1., , Nilgiri [First biosphere reserve, established in India (1986)], , 2., , Namdapha, , Arunachal Pradesh, , 3., , Nanda Devi (1988), , Uttar Pradesh, , 4., , Uttarakhand (Valley of flowers), , Uttaranchal in North Western Himalayas, , 5., , North Islands of Andamans, , Andaman and Nicobar Islands, , 6., , Gulf of Mannar, , Tamil Nadu, , 7., , Kaziranga, , Assam, , 8., , Sunderbans, , West Bengal, , 9., , Thar Deserts, , Rajasthan, , 10., , Manas, , Assam, , 11., , Kanha, , Madhya Pradesh, , 12., , Nokrek (Tura range), , Meghalaya, , 13., , Great Nicobar, , Andaman and Nicobar, , 14., , Little Rann of Kutch, , Gujarat, , Kerala, Karnataka and Tamil Nadu., , Table : Some special projects for endangered animal species., Name of Project, , Characters, , 1., , Tiger project, , There are 25 tiger reserves in 13 or 19 states to save tigers., It was launched on 1st April, 1973., , 2., , Lion project (Gir Lion Project), , Asian lion is found only in Gir forest of Gujarat. It was, started in 1972., , 3., , Crocodile breeding project, , It was started in Orissa to save crocodiles in 1975. There are, three species of crocodiles in India : (i) saltwater (Crocodylus, porosus), (ii) fresh water muggar (Crocodylus palustris),, (iii) gharial (Gavialis gangeticus). Being run by UNDP and, central govt., , 4., , Rhino conservation project, , It was started in Assam in 1987. Dudhwa National park was, selected for the rhino reintroduction project., , 5., , Snow leopard project, , There are 12 snowleopard reserves in Himalayas., , 6., , Hangul project, , It was started in 1970 to protect hangul or Kashmiri stag, (Cervus elephus hanglu)., , 7., , Browantlered deer project, , It was started in Manipur since 1977 to protect browantlered, deer (Cervus eldi eldi)., , 8., , Musk deer project, , It was started by U.P. Government, IUCN and Central, Government to protect muskdeer (Moschus moschiferus)., , 9., , Elephant project, , It has been recently started (1991) to protect elephants., , Yak Project Research Centre, , It is in Arunachal Pradesh., , 10.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŚĚĘĺňŐńŐĹť– ·– ◙ĚňĚŚĽĘ– ◄ňĹĽňĚĚŕĽňĹ, , 577, , Chapter 64, , Biotechnology & Genetic, Engineering, BIOTECHNOLOGY, l, , l, , l, , l, , l, , l, , l, , l, , l, , Biotechnology means any technological, application that uses biological systems, living, organisms, or derivatives thereof, to make or, modify products or processes for specific use., Biotechnology is an important tool used for the, production of food crops, livestock management,, human health care, chemical industries and, environmental management., “Biotechnology” generally refers to recombinant, DNA based and/or tissue culture based processes, that have only been commercialized since the 1970s., One aspect of biotechnology is the direct use of, organisms for the manufacture of organic products, (examples include beer and milk products)., Biotechnology is also used to recycle, treat waste,, clean up sites contaminated by industrial activities, (bioremediation), and produce biological weapons., There are also applications of biotechnology that, do not use living organisms. Examples are DNA, microarrays used in genetics and radioactive tracers, used in medicine., Red biotechnology is applied to medical processes., Some examples are the designing of organisms to, produce antibiotics, and the engineering of genetic, cures through genomic manipulation., White biotechnology, also known as grey, biotechnology, is biotechnology applied to, industrial processes., Green biotechnology is biotechnology applied to, agricultural processes. An example is the designing, of transgenic plants to grow under specific, environmental conditions or in the presence (or, absence) of certain agricultural chemicals., , l, , Applications of biotechnology are –, –, Food and dairy products : Yoghurt, cheese, and butter require specific strains of micro, organisms during their preparation., –, Alcoholic and nonalcoholic beverages :, Beers, wines, etc. are produced through, fermentation of different food by suitable, microorganisms. Curing of coffee beans and, tea leaves is also a microbial process., –, Biofertilizers : They are nitrogen fixing micro, organism which may live freely in soil or in, association with plants., –, Organic acid : A number of organic acids, (acetic acid, lactic acid, etc.) are obtained, through biotechnology., –, Vitamins : Some vitamins are still, manufactured with the help of micro, organisms. Food yeast is rich in both proteins, and vitamins., –, Antibiotics : Barring a few, all others are, products of microorganisms., –, Vaccines : These contain attenuated or killed, pathogens or their antigens., –, Monoclonal antibodies : Antibodies against, pathogen can now be obtained in pure form, from clonal cultures., –, Hormones : Insulin, growth hormone and, other hormones are presently synthesized, through the use of microbes and genetic, engineering., –, Tissue culture : An important tool for, improvement of agriculture, forestry, synthesis, of specific biochemicals etc., –, Genetic engineering : Recombinant DNA, technology is applied to several
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 578, , l, , l, , l, l, l, , l, , l, , l, , l, l, l, l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , biotechnological processes in obtaining, particular biochemicals, improvement of, genetic make–up of an organism and fighting, undertaken for production of offspring of, desired parents., –, Steroids : Microorganisms are employed for, transformation of one type of steroids into, other types. These are required in antifertility, formulations., Yeast, (Saccharomyces cerevisiae) is the most, important and most extensively used micro, organism in biotechnology., Yeast cells are used in the manufacture of bread, and also as a source of food, vitamins and other, growth factors., There are two types of yeasts: baker’s yeast and, alcohol yeast., Baker’s yeast is grown on molasses and sold as, a food flavouring agent., Alcohol yeast is used by brewing industry for the, production of different types of alcoholic beverages, depending upon the medium and fermenting agent., There are two types of fermentation process: batch, fermentation (or closed system) and continuous, process (or open system)., Downstream processing is the name given to the, stage after fermentation when desired product, is recovered and purified., Cheese is prepared by the coagulation of casein, and other minor milk proteins (curdling of milk) by, an enzyme rennin extracted from calf gastric, mucosa., Streptococcus and Lactobacillus species are, involved in the manufacture of most cheese., In cheese manufacture, microorganisms are, important in both souring and ripening processes., Semisoft blue Roquefort cheese of France is, produced using the mold Penicillium roqueforti., Yoghurt is a preserved milk product having a, distinct taste and a thick texture than milk., Yoghurt is made by fermenting whole milk with a, mixture of Lactobacillus bulgaricus, Streptococcus, lactis and S. thermophilus at 40º to 46ºC., Gibberellins, a plant growth hormone or, phytohormone is obtained from a fungus called, Fusarium moniliformae (or Gibberella fujikuroi)., This was isolated by Yabuta and Sumuki (1939)., At this time, over 52 gibberellins have been, discovered from different plants., , l, , l, l, , l, l, , l, l, , l, l, , l, , l, l, , l, l, l, , l, , Louis Pasteur found that beer is produced by activity, of yeast and yeast like microorganisms. Yeast, species used in alcoholic fermentation are, Saccharomyces cerevisiae (Brewer’s yeast), S., ellopsoidens (Wine yeast), S. sake (Sake yeast) and, S. pireformis (Ginger beer/Ale yeast)., Acetic acid is the most important organic acid used, in industry., Vinegar is the product resulting from the, conversion of ethyl alcohol to acetic acid by the, bacteria Acetobacter., Lactic acid was the first acid to be produced, microbially by Lactobacillus delbrueckii., Aspergillus niger and Mucor sp and yeast can, ferment sugar to produce citric acid. It is used in, medicine, flavouring extracts food and candies,, manufacturing of ink, dyeing and engraving., Gallic acid is obtained using Aspergillus niger., Gluconic acid is manufactured with the help of, Penicillium purpurogenum and P. chrysogerium. It, is used in pharmaceuticals. Calcium gluconate is, used as a source of calcium in feeding infants, and pregnant women and for treatment of milk, fever in high producing dairy cows., Dextran is a plasma expander used in blood, transfusions., Dextran is a complex polysaccharide prepared, either through partial hydrolysis of starch or, polymerization of sucrose by the bacterium, Leuconostoc mesenteroides., Some important enzymes produced industrially by, microbes are amylase, glucoamylase, glucose, isomerase and proteases., Amylase which attacks starch is used in the, manufacture of beer, bread and textiles., Glucose can be attacked by glucose isomerase to, produce fructose corn syrup which is sweeter, than either glucose or sucrose and is used in the, production of soft drinks and in baking industry, to sweeten biscuits and cakes., The enzyme Tissue Plasminogen Activator (TPA), is used for dissolving blood clots., The technique of anchoring an enzyme in or on, support material is called immobilization., Immobilized enzymes are generally used for, bioreactors in a continuous process., Crosslinking of enzymes involves the chemical
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 579, , ▲ĽŐŚĚĘĺňŐńŐĹť– ·– ◙ĚňĚŚĽĘ– ◄ňĹĽňĚĚŕĽňĹ, , l, l, l, l, , l, , l, , reaction of the amino group of enzyme protein with, glutaraldehyde., The bonding of enzyme can be done through, adsorption, ionic bonding or covalent bonding., Enzyme inclusion involves the incorporation of, enzyme into a semipermeable membrane., Most of the vitamins are made commercially by, chemical synthesis., Vitamin C was the first vitamin to be produced, by a fermentation process using Acetobacter, a wild, bacterium., Bacteria used for industrial production of vitamin, B 12 are Propionibacterium shermanii,, P. frendenreichii and Pseudomonas denitrificans., Vitamin B2 (Riboflavin) is synthesized by many, microorganisms including bacteria, yeasts and, fungi. The fungus, Ashbya gossypii is used for the, microbial production of vitamin B2., , l, , l, , l, l, , l, l, , Antibiotics are chemical substances produced by, certain microorganisms that kill or inhibit the, growth of other microorganisms., Alexander Fleming, Howard Florey and Ernst, Boris Chain received Nobel Prize in 1945 for the, discovery and development of Penicillin., Streptomycin was first isolated by Selman A., Waksman., Grampositive bacteria are usually more sensitive, to antibiotics than Gramnegative bacteria., An antibiotic that acts on a variety of pathogenic, organisms is called a broad spectrum antibiotic., Vaccination or administration of vaccine was, discovered by Edward Jenner (1796) when he, immunised a boy against small pox by inoculating, him with milder cow pox. The technique of, attenuating or weakening of pathogen was, , Table : Types of antibiotic with their source and action, Source, , Action, , Penicillin, , Penicillium chrysogenum, P. notatum +, Phenyl Acetic Acid, , Tonsilitis, Sore Throat, Gonorrhoea,, Rheumatic Fever, some Pneumonia types, , Griseofulvin, , Penicillium griseofulvum, , Antifungal, especially for Ringworm, , Nystatin, , Streptomyces noursei, , Antifungal for Candidiasis and overgrowth, of Intestinal Fungi during excessive, antibiotic treatment., , Hamycin, , Streptomyces pimprei, , Antifungal for Thrush, , Fumagillin, , Aspergillus fumigatus, , Broad spectrum antibacterial especially, against Salmonella and Shigella., , Bacitracin, , Bacillus licheniformis, , Syphilis, Lymphonema or Reticulosis., , Streptomycin, , Streptomyces griseus, , Meningitis, Pneumonia, Tuberculosis and, Local Infections. Toxic in some through, eighth cranial nerve., , Chloramphenicol, Chloromycetin, , Streptomyces venezyelae, S. lavendulae, Now, synthetic, , Typhoid, Typhus, Whooping cough,, Atypical Pneumonia, Bacterial Urinary, Infections, , Tetracyclines/, Aureomycin, , Streptomyces aureofaciens, , Viral pneumonia, Osteomyelitis, Whooping, Cough. Eye infections., , Oxytetracycline/, Terramycin, , Chlorotetracycline ® Hydrogenation, Streptomyces rimosus, , Intestinal and Urinary Infections, (Spirochaetes, Rickettsiae, Viruses), , Erythromycin, , Streptomyces erythreus (= S. erythraeus), , Typhoid, Common Pneumonia, Diphtheria,, Whooping Cough, etc., , Gentamycin, , Micromonospora purpurea, , Effective against Gram (+) bacteria, , Polymixin, , Bacillus polymyxa, , Antifungal, , Antibiotics
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 580, , l, , l, , l, l, , l, , l, l, l, l, , l, , l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , discovered by Louis Pasteur (1879, against cholera)., Vaccines are suspensions or killed or modified, pathogenic microorganisms; when injected into, an animal, these produce immunity to a particular, disease., Biotechnology has proved successful in the, development of recombinant vaccines also known, as ‘secondgeneration vaccines’ and even ‘third, generation vaccines’ (synthesized vaccines)., Hepatitis B vaccine is a second generation vaccine., Vaccines produced using genetic engineering can, usually be made faster than those manufactured by, traditional methods., Genetically engineered vaccines are safer, more, reproducible and can be administered in high doses, without fear of side effects., Monoclonal antibodies are made outside the body, by the hybrid cell cultures known as hybridomas., The cells obtained from cancerous tumors are, known as myeloma., Blymphocytes are mixed with myeloma cells, resulting in hybridoma., The hybridoma cells are identified when all cells, are grown in a medium deficient in the nutrient, needed by myeloma cells., To produce monoclonal antibodies, Bcells are, removed from the spleen of an animal that has, been challenged with the relevant antigen., These Bcells are then fused with myeloma tumor, cells that can grow indefinitely in culture (myeloma, is a Bcell cancer)., This fusion is performed by making the cell, membranes more permeable., The fused hybrid cells (called hybridomas), being, cancer cells, will multiply rapidly and indefinitely, and will produce large amounts of the desired, antibodies., They have to be selected and subsequently cloned, by limiting dilution. Supplemental media containing, Interleukin6 (such as briclone) are essential for, this step., Monoclonal antibodies are true magic bullets,, striking specific molecules and leaving the rest of, the body unharmed., Monoclonal antibodies (mAb) are antibodies that, are identical because they were produced by one, type of immune cell and are all clones of a single, , l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , parent cell., One clinical application of monoclonal antibodies, is immune suppression for kidney transplantation., Monoclonal antibodies have also been used in, genetics engineering for identifying and, measuring levels of gene products not detectable, by other methods., Monoclonal antibodies are used in pregnancy, testing, diagnosis of disease, treatment of disease,, preventing rejection of transplants and tissue, typing for transplants., They are also very useful in immunohistochemistry, which detect antigen in fixed tissue sections., Monoclonal antibodies can also be used, to purify a substance with techniques called, immunoprecipitation and affinity chromatography., One possible treatment for cancer involves, monoclonal antibodies that bind only to cancer cell, specific antigens and induce an immunological, response against the target cancer cell., Such mAb could also be modified for delivery of, a toxin, radioisotope, cytokinin or other active, conjugate; it is also possible to design bispecific, antibodies that can bind with their Fab regions both, to target antigen and to a conjugate or effector cell., In fact, every intact antibody can bind to cell, receptors or other proteins with its Fc region., Insulin is a protein consisting of two short, polypeptide chains A and B of 21 and 30 amino, acids respectively interconnected by two disulphide, bridges., Insulin regulates sugar metabolism and, insufficiency or lack of insulin leads to high blood, sugar level and the disease is called diabetes., Banting and Best (1921) isolated insulin from, pancreas of dog and demonstrated its efficacy in, curing diabetes in humans., In 1983, 5 July, American Company Eli Lilly, prepared two DNA sequences corresponding to A, and B insulin chains when introduced in plasmids, of E. coli, insulin chains were formed. They were, extracted and fused to produced humulin (human, insulin)., Growth hormone is required to overcome pituitary, dwarfism caused by nonsecretion of hormone from, anterior pituitary., The DNA/gene cDIVA (without introns) required, for synthesis of growth hormone is first synthesized
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŚĚĘĺňŐńŐĹť– ·– ◙ĚňĚŚĽĘ– ◄ňĹĽňĚĚŕĽňĹ, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , l, , l, , and integrated with bacterial plasmid (trp gene)., The latter produces the required hormone. It has, been also been produced produced inside silk worm., Interferons (antiviral proteins) were produced by, Charles Weismann of Zurich University through, recombinantDNA technology in E. coli in 1980., Transgenic plants are plants with specific genes, or traits obtained through genetic engineering of, DNA recombinant technology, e.g., resistance to, hornworm larvae (tomato), resistance to corn borer, (Bt corn with gene from Bacillus thuringiensis),, resistance to overripening (tomato), good protein, content (potato), herbicide resistance (tobacco)., Transgenic animals are animals having specific, genes obtained from outside, e.g., tissue, plasminogen activator in milk (goat), blood clotting, factor VIII (sheep from progeny of ewe Eithel)., Cowdung, farm refuse, garbage etc are placed in, biogas plants where anaerobic conditions allow, methane bacteria to produce methane and other, fuel gases called as biogas. The organic remains of, the biogas plants are used as manure., Biofertilizers are mostly nitrogen fixing micro, organisms which may live free in the soil or form, associations with plants. Special strains of these, organisms are now inoculated to soil or seeds., The main technique involved in agricultural, biotechnology is called tissue culture., The medicinally important plant products can be, manufactured on a commercial scale by using cell, and tissue culture techniques., Recombinant DNA technology is applied to several, biotechnological process in obtaining particular, biochemicals, improvement of genetic make up of, an organism and fighting genetic defects., Test tube babies and embryo transplants are now, being routinely undertaken for production of, offspring of desired parents., Steroids are complex crystalline lipids having, tetracyclic hydrocarbon core, with one 5carbon, ring and three 6carbon rings., Most steroid bioconversions involve hydroxylation, and a variety of different fungi are used, industrially to carry out one or another specific, hydroxylations., Four major steroids currently produced by, bioconversion are hydrocortisone, cortisone,, , l, , l, , 581, , prednisone and prednisolone., Some microbes used in microbial transformations, of steroids are Rhizopus nigricans, R. arrihizus,, Cunninghamella blakesleeana, Curvularia lunata, and Corynebacterium simplex., Steroids are used medicinally in correcting, hormonal imbalance, as anabolic stimulants,, birth control pills (progesterone ± estrogen),, antifertility drugs (e.g., diosgenin), anti, inflammatories, for relieving pain and, suppressing immune responses., , Biopatent, Biopiracy and Biowar, l, , l, , l, , l, , l, , l, , l, , A patent is a monopoly granted to a person who, has either invented a new and useful article, made, and improvement of an existing article or invented, a new process of making an articles., A patent is granted by the legal system, therefore, it is a subject which cannot be fully understood, without knowing the law on the subject., Biopatents are awarded for the following as strains, of microorganisms, cell lines, genetically modified, strains of plants and animals, DNA sequences, the, proteins encoded by DNA sequences, various, biotechnological procedures, production processes,, products and product applications., The human breast cancer gene (BRCA1) was, patented in the US once its base sequence had been, determined and attempts are being made to patent, the second breast cancer gene (BRCA2)., Biopiracy (or biocolonialism) is the appropriation, of another’s knowledge of use of biological, resources., Intellectual Property Right (IPR) claims by the, formal sector over the work of the informal, constitutes biopiracy., Three aspects of biopiracy are –, – Intellectual Piracy: This makes a false claim, to novelty and invention, even though the, knowledge has evolved since ancient time., – Resource Piracy: This divests scarce biological, resources to monopoly control of corporations, thus depriving communities and indigenous, practitioners., – Economic Piracy: It creates market monopolies, and excludes the original innovators from their, rightful share to local, national and international, markets.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 582, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Neem, Azadirachta indica, has been used by the, people of India in a variety of ways for time, immemorial., The patenting of the fungicidal properties of neem, was an example of biopiracy., An American university patented the healing, properties of turmeric powder, cherished in India, since ancient times for its powder to cure the, wounds., Biological resources or bioresources include all, those organisms that can be used to derive, commercial benefits., Traditional knowledge related to bioresources is, the knowledge developed by various communities, over long periods of history, regarding the utilization, of the bioresources, e.g., use of herbs as drugs., Biowar or biological war or bioterrorism is the, deployment of biological weapons against people,, their crops and animals., A biological weapon or bioweapon carries and, delivers to the target organism a pathological, biological agent or a toxin derived from it., Massproduced pathogens or their toxins are, delivered either as powder or in the form of spray,, using a variety of delivery devices., Among weapons of mass destruction, biological, weapons are more destructive than chemical, weapons including nerve gas., Bioweapons (a) are lowcost weapons, (b) cause, far more casualities than chemical or conventional, weapons, and (c) bioweapon agents are invisible, and extremely difficult to detect., The first reported use of biological weapons was, in 5th century BC, when Assyrians poisoned enemy, wells with rye ergot., During many occasions, smallpox was used as a, biological weapon., Iraq is reported to have conducted research and, development work on anthrax, botulin, aflatoxin,, wheat cover smut and ricin., Anthrax spores were used against USA and her, allied countries by AlQaeda activists., Various poisons produced by different biological, pathogens act like some neurotoxin, such as, saxitoxin can kill individuals by blocking nerve, conduction directly., The possible defences against bioweapons include, the use of respirator or gas mask, vaccination,, , l, , l, , l, , l, , l, l, , administration of appropriate antibiotics and, decontamination., Biological warfare agents include –, – Pathogens : Smallpox virus, Viral, encephalitides, Viral haemorrhagic fevers,, Bacillus anthracis, Brucella suis, Coxiella, burnetii, Francisella tularensis, Yersinia pestis., – Toxins : Botulinum, Ricin, Stylococcal, enterotoxin B., – Anticrop agents : Rice blast, Rice stem rust,, wheat stem rust., Bioethics is the branch of ethics, philosophy and, social commentary that deals with the biological, sciences and their potential impact on society., The major bioethical concerns pertaining to, biotechnology are –, – Use of animals in biotechnology causes great, suffering to them., – When animals are used for production of, pharmaceutical proteins, they are virtually, reduced to the status of a ‘factory’., – Introduction of a transgene from one species, into another species violates the ‘integrity of, species’., – Transfer of human genes into animals (and vice, versa) dilutes the concept of ‘humanness’., – Biotechnoloy is disrespectful to living beings, and only exploits them for the benefit of human, beings., – Biotechnology may pose unforeseen risks to, the environment, including risk to biodiversity., Bioinformatics is an interdisciplinary field which, addresses biological problems using computational, techniques., The field is also often referred to as computational, biology., It plays a key role in various areas, such as functional, genomics, structural genomics, and proteomics, and, forms a key component in the biotechnology and, pharmaceutical sector., , GENETIC ENGINEERING, l, , Genetic engineering is the technology involved in, synthesis of artificial genes, repair of genes, through fusion, deletion, inversion, shifting of, genes, products of recombinant DNA &, manipulating them for improvement in human
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŚĚĘĺňŐńŐĹť– ·– ◙ĚňĚŚĽĘ– ◄ňĹĽňĚĚŕĽňĹ, , l, l, l, , l, , l, , l, l, , l, , l, l, l, , l, , beings, plants, animals and microbes., Genetic engineering is the most powerful, technique available in applied genetics., An important aspect of genetic engineering is, recombinant DNA technology., Recombinant DNA technology is employed for, combining DNA from two different organisms to, produce recombinant DNA., The process involves the following steps –, –, Separation of a desired DNA segment from, donor organism, –, Selection of suitable vector, –, Cutting DNA into specific fragments using, enzyme restriction endonuclease and joining, the fragments with the help of enzyme, ligase., The technology of genetic engineering came into, existence after the introduction of genes of SV40, into the bacterium with the help of lambda phage, (Berg 1970s)., Paul Berg is the father of genetic engineering, (Nobel Prize, 1980)., First nonfunctional artificial gene of alanine, t RNA having 77 nucleotides pairs was synthesized, by H.G.Khorana et al (1968)., First functional artificial gene was tyrosine tRNA, gene with 207 nucleotide pairs (H.G.Khorana et al, 1971)., In 1981, Edge et al synthesized IFNa gene (human, leucocyte interferon gene) with 514 base pairs., Addition of DNA ligases produces recombinant, DNA., The technology associated with the construction, and application of recombinant DNA (which is, generated in vitro by covalently joining DNA, molecules from different sources) is referred to as, genetic engineering or gene splicing or gene, manipulation., Enzymes used in genetic engineering to perform, specific functions are –, –, Restriction endonuclease (cut DNA at, specific sites), –, DNA ligase (join the cut DNA), –, Exonuclease (digest the base pairs on 5¢ or 3¢, end of a single stranded DNA or at single, stranded nicks or gaps in double stranded, DNA), , Endonuclease (cleave the double stranded, DNA at any point except the ends), –, DNA polymerase (polymerises the DNA, synthesis on DNA template), –, Reverse transcriptase (used to synthesize, cDNA by using mRNA template)., Vectors (also known as vehicle DNAs) are those, DNA molecules that can carry a foreign DNA, fragment when inserted into it., The vectors are grouped into bacterial plasmids,, bacteriophage, cosmids and phasmid., The vehicle DNA carrying passenger DNA is, called recombinant DNA (chimeric DNA)., Plasmids (like pBR322, pBR324, pC194 etc) are the, extrachromosomal, selfreplicating and double, stranded closed and circular DNA molecules present, in the bacterial cell., Cohen et al (1973) for the first time reported the, cloning DNA by using plasmid as vector., Bacteriophages (a virus that eats upon bacteria) are, required for cloning of large DNA fragment., The cosmids (like pJC74, pJC720 etc.) can be defined, as the hybrid vectors derived from plasmids, which contain cos site of phage l., A phage genome containing att site and one or, more plasmid molecule (s) is known as phasmid., One use of transgenic animals is to produce, relatively large quantities of rare and expensive, proteins for use in medicine, a process sometimes, referred to as ‘pharming’ of drugs., Detecting mutant genes in an individual is known, as genetic screening., Genetic screening reduces suffering of both, victims of genetic disease (Thalassemia, sickle cell, anaemia) and their families., Eugenics is the study of the possible improvement, of the genetics of a species., Genetic counselling is the advice given to a couple, or prospective couple or their families about the, possibility of genetic disorders in the future, (unconceived) baby and in an early foetus as an aid, to decision making about marriage or having, children. Advice is given by physicians or, professional human geneticists. They are called, genetic counsellors., Genetic engineering techniques give a scope to learn, a great deal about the human genome., –, , l, , l, l, l, , l, l, l, , l, l, , l, l, , l, l, , l, , 583
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 584, , l, l, , l, , l, , l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , The human genome contains some 3.2 billion bases., Genome sequencing has revealed that organisms, have many genes in common. Surprisingly, humans, have a small genome, only a third larger than, nematode worm., Proteomics, the next step of human genome project, deals with cataloguing and analysis of every protein, in the human body., A biochip is a discrete collection of gene fragments, on a stampsized chip that can be used to screen, for the presence of particular gene variants., Biochips allow rapid screening of gene profiles, a, tool that promises to have a revolutionary impact, on medicine and society., Biochips can help in identifying precise forms of, cancer., Gene therapy is the treatment of disease by, replacing, altering, or supplementing a gene that is, absent or abnormal and whose absence or, abnormality is responsible for the disease. Gene, therapy is unique in that it employs the genetic, material, DNA, itself as the means of treatment., During gene therapy, DNA that codes for specific, genes is delivered to individual cells in the body., Gene therapy is being used in many ways. For, example, to:, –, Replace missing or defective genes, –, Deliver genes that speed the destruction of, cancer cells, –, Supply genes that cause cancer cells to revert, back to normal cells, –, Deliver bacterial or viral genes as a form of, vaccination, –, Provide genes that promote or impede the, growth of new tissue, –, Deliver genes that stimulate the healing of, damaged tissue., A large variety of genes are now being tested for, use in gene therapy. Examples include : a gene for, the treatment of cystic fibrosis (a gene called CFTR, that regulates chloride); genes for factors VIII, and IX, deficiency of which is responsible for, classic haemophilia (haemophilia A) and another, form of haemophilia (haemophilia B), respectively;, genes called E1A and P53 that cause cancer cells, to undergo cell death or revert to normal; AC6, gene which increases the ability of the heart to, , contract and may help in heart failure; and VEGF,, a gene that induces the growth of new blood vessels, (angiogenesis) of use in blood vessel disease., , Cloning, l, l, l, l, , l, , l, , l, , l, , l, , l, l, , Cloning is the production of copies that are, genetically identical to the parent., Cloning is absent in higher animals except for, occasional monozygotic split ups., Cloning is of three types – cell cloning, gene, cloning and organismal cloning., Cell cloning is the formation of multiple copies of, the same cell. Cells of a clone are identical, genetically, morphologically and physiologically., Totipotency or ability to divide indefinitely and, differentiate into full fledged organisms is present, in most plants cells. In case of animals, it is found, only in zygote (fertilized egg) and embryonic stem, cells., Animal cells can have pleuripotency or potential, ability to develop into any other type of cell in, the animal body, e.g., kidney cells, heart cells,, liver cells, nerve cells., HeLa cells are aneuploid strain of cell lines from, cervix carcinoma of a patient Henrietta Lacks which, have been grown continuously since 1952. They, have been used in the study of various life processes, including infection by viruses., Hybrid cells are obtained through protoplast fusion, of human and mouse cells (first carried out by, Burski et al, 1960). Hybrid cells can be made to, grow and divide indefinitely under proper culture, conditions. The cells are used for mapping genes,, study of cancer formation and regulation of gene, expression., Recently techniques are being perfected to grow, full fledged organs from small pieces containing, stem cells and organ cells. Pig organs can also be, used in organ transplantation provided they are, genetically modified to prevent rejection from, human immune system. This technique is called, organ culture., Gene cloning is the formation of multiple copies, of same gene., It is achieved by recombinant DNA technology., The steps include –, –, The production of a lineage of cells all of, which contain one kind of DNA fragment of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŚĚĘĺňŐńŐĹť– ·– ◙ĚňĚŚĽĘ– ◄ňĹĽňĚĚŕĽňĹ, , l, , l, , l, , l, , l, , l, , interest derived from a population of many, kinds of DNA fragments., –, Operational by inserting (recombining) a, population of DNA molecules., –, Known to contain the DNA of interest, into, a population of vector DNA molecules in such, a way that each vector molecule contains only, a single DNA molecule from the original, population., –, Transforming a population of host cells with, the vector DNA recombinants such that each, host cell takes up only one vector., –, Growing single host cells separately (cloning), by plating at low density to form a collection, of separate colonies., –, Screening the colonies (clones) formed for, the presence of the DNA of interest., Organismal cloning is the formation of one or, more genetically identical individual from a single, parent., The lamb Dolly is the first successful clone derived, from differentiated animal cell (Wilmut and, Campbell 1997)., They took cells from the udder of a six year old, sheep. The cells were arrested in G0 – phase by, serum starvation. Unfertilized egg of another adult, sheep was taken out when it was receiving optimum, amount of maturation promoting factors. The egg, was denucleated. Nondividing nucleus of an udder, cell was taken out and inserted in the denucleated, egg. In nutrient medium the egg began to undergo, cleavage. The young embryo was implanted in the, womb of a third sheep. The surrogate mother gave, birth to normal healthy lamb, Dolly, on February, 13, 1997., In molecular cloning, the DNA fragment of interest, is amplified in vivo in a population of proliferating, cells., A cloning vector is a genetic element derived from, a plasmid or virus which is exploited to carry, extra DNA (donor, foreign, insert or passenger, DNA)., Crown gall producing bacterium, Agrobacterium, tumefaciens, possesses tumor inducing or Ti, plasmids. The plasmids pass the tumor producing, gene into the genome of the host plant. The, transformed host genome produces galls. Because, , l, , l, l, , l, , l, , l, , l, , l, , 585, , of this Agrobacterium functions as natural genetic, engineer of plants., The modified plasmid of Agrobacterium is made, to carry the desired gene. It is called TDNA. The, same can be directly inserted into nucleus of host, plant cells., Alternately TDNA is also made to carry a gene for, antibiotic resistance., Agrobacterium mediated gene cloning has been, carried out in many dicotyledonous plants (e.g.,, sunflower, cotton, potato, tomato) as well as all the, major cereals recently (viz. wheat, maize, rice)., The animal, derived from a mixture of two, genetically different types of cells, some derived, from the normal stem cells and some derived from, the transformed stem cells, is known as chimera., Gene bank or genomic library is a complete, collection of cloned DNA fragments which, comprises the entire genome of an organism., Gene banks are a means of preserving genetic, material, be it plant or animal. In plants, this could, be freezing the plant, or the seeds themselves., In plants, it is possible to unfreeze the material and, sow it, however, in animals, a living female is, required for artificial insemination., Despite this, it has proven very difficult to utilize, the genes after freezing., , Techniques of genetic engineering, PCR, l, Polymerase chain reaction (PCR) is a, biochemistry and molecular biology technique for, enzymatically replicating DNA without using a, living organism, such as E. coli or yeast., l, Like amplification using living organisms, the, technique allows a small amount of DNA to be, amplified exponentially., l, PCR can amplify specific sequences or add, sequences (such as endonuclease recognition, sequences) as primers to cloned DNA., l, The enzyme used in PCR is Taq polymerase., l, As PCR is an in vitro technique, it can be performed, without restrictions on the form of DNA and it can, be extensively modified to perform a wide array of, genetic manipulations., l, PCR is commonly used in medical and biological, research labs for a variety of tasks, such as the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 586, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Products from genetically engineered microbes, , l, l, , 1., , Escherichia coli (gut bacterium), , Human insulin, human growth factor, interferons, interleukin,, tissue plasminogen activator, epidermal growth factors, lung, surfactant protein, factor VIII, viral vaccines., , 2., , Bacillus thuringiensis (soil bacterium), , Endotoxin (Bt toxin), highly potent, safe and biodegradable, insecticide., , 3., , Rhizobium meliloti (symbiont nitrogen, fixing bacteria), , Transfer of ‘Nif’ genes to cereal crops., , 4., , Pseudomonas fluorescence (bacterium), , Prevents frost damage (e.g., Strawberry) on which it grows., Biochemicals extracted from bacterium also have similar effect., , 5., , Pseudomonas putida (bacterium), , Bioremediation or purification of environment – scavenging, oil spills by digesting hydrocarbons, metabolism of heavy, metals and other biochemicals., , 6., , Trichoderma (fungus), , Produces enzyme chitinase for biocontrol of fungal diseases, in plants., , 7., , Trametes (fungus), , Removal of lignin from wood pulp., , detection of hereditary diseases, the, identification of genetic fingerprints, the, diagnosis of infectious diseases, the cloning of, genes, paternity testing, and DNA computing., The reaction is easy to execute., It requires no more than a test tube, a few simple, reagents, and a source of heat.”, , RAPD, l, RAPD stands for random amplification of, polymorphic DNA., l, It is a type of PCR reaction, but the segments of, DNA that are amplified are random., l, The scientist performing RAPD creates several, arbitrary, short primers (812 nucleotides), then, proceeds with the PCR using a large template of, genomic DNA, hoping that fragments will amplify., l, No knowledge of the DNA sequence for the targeted, gene is required, as the primers will bind somewhere, in the sequence, but it is exactly not certain where., l, This makes the method popular for comparing the, DNA of biological systems that have not had the, attention of the scientific community, or in a system, in which relatively few DNA sequences are, compared (it is not suitable for forming a DNA, databank)., l, Due to the fact that it relies on a large, intact DNA, template sequence, it has some limitations in the, use of degraded DNA samples., , l, , Its resolving power is much lower than targeted,, species specific DNA comparison methods, such, as short tandem repeats., , RFLP, l, In molecular biology, the term restriction fragment, length polymorphism (or RFLP, often pronounced, “riflip”) is used in two related contexts: as a, characteristic of DNA molecules (arising from their, different nucleotide sequences) by which they may be, distinguished, and as the laboratory technique which, uses this characteristic to compare DNA molecules., l, The technique is utilized in genetic fingerprinting, and paternity testing., DNA fingerprinting or Genetic fingerprinting, l, DNA finger printing is the technique in which the, banding pattern of DNA fragments is compared, and can be used in many species, including human,, to indicate relatedness (used for rape victim,, paternity, other criminals)., l, Dermatoglyphics is the science of finger printing, which was developed during a murder investigation, in Jalpaiguri (WB) in 1897., l, It deals with the study of pattern of ridges of the, skin of fingers, palms, toes and soles., l, Dermatoglyphics is used in establishing identity, of individuals. It can also indicate genetic, abnormalities.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŚĚĘĺňŐńŐĹť– ·– ◙ĚňĚŚĽĘ– ◄ňĹĽňĚĚŕĽňĹ–, l, , l, , l, , l, , l, , l, l, l, l, , l, , l, l, , l, , l, , More sensitive version of DNA finger printing, is DNA profiling (most commonly used method in, forensic work)., Genetic fingerprinting, DNA testing, DNA, typing, and DNA profiling are techniques used, to distinguish between individuals of the same, species using only samples of their DNA., Its invention by Sir Alec Jeffreys at the University, of Leicester was announced in 1985. Two humans, will have the vast majority of their DNA sequence, in common., Genetic fingerprinting exploits highly variable, repeating sequences called minisatellites, (VNTR’s)., DNA of each individual has some noncistronic, hyper variable repeat minisatellite sequence. These, repeat minisatellite sequence flanked by conserved, restriction site are commonly called as (VNTRs), variable number of tandem repeats., VNTRs are similar in twins only., Two unrelated humans will be likely to have different, numbers of minisatellites at a given locus., By using PCR enough DNA is obtained to detect, the number of repeats at several loci., It is possible to establish a match that is extremely, unlikely to have arisen by coincidence, except in, the case of identical twins, who will have identical, genetic profiles., Genetic fingerprinting is used in forensic science,, to match suspects to samples of blood, hair, saliva, or semen., It has also led to several exonerations of formerly, convicted suspects., It is also used in such applications as identifying, human remains, paternity testing, matching organ, donors, studying populations of wild animals,, and establishing the province or composition of, foods., It has also been used to generate hypothesis on, the pattern of the human diaspora in prehistoric, times., Testing is subject to the legal code of the jurisdiction, in which it is performed., , Southern blotting, l, Southern blotting is a method in molecular biology, of enhancing the result of an agarose gel, , l, l, , 587, , electrophoresis by marking specific DNA, sequences., The method is named after its inventor, the British, biologist Edwin Southern., This caused other blot methods to be named, similarly as plays on Southern’s name (for, example, Western blot, Northern b lot,, Southwestern blot (Detection of RNA is termed, northern blotting.)., , Western blotting, l, A western blot is a method in molecular biology/, biochemistry/immunogenetics to detect protein, in a given sample of tissue homogenate or, extract., l, It uses gel electrophoresis to separate denatured, proteins by mass. The proteins are then transferred, out of the gel and onto a membrane (typically, nitrocellulose), where they are “probed” using, antibodies specific to the protein., l, As a result, researchers can examine the amount of, protein in a given sample and compare levels, between several groups., l, Other techniques also using antibodies allow, detection of proteins in tissues (immunohisto, chemistry) and cells (immunocytochemistry)., l, The name western blot was given to the technique, by W. Neal Burnette (1981)., , Application of genetic engineering, l, , l, , l, , l, l, , l, , Human insulin or humulin is the first genetically, engineered pharmaceutical product, developed by, Eli Lilly and company in 1982., Genetech, a Californiabased company, have, produced human growth hormone (hGH) from, genetically engineered bacteria., Somatostatin is the first polypeptide, which was, expressed in E. coli as a part of the fusion, peptide., BST or Bovine Somatotropin is produced for a, large quantity of milk production in cows., It is possible to cure phenylketonuria disease by, using recombinant DNA techniques in early period, of pregnancy., Urokinase is involved in dissolution of blood clots., It has been synthesized in huge quantity by using, genetically engineered bacteria with urokinase, genes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 588, , ŕďőĽę– ĐĽŐńŐĹť, , Outline of applications of genetic engineering, techniques in different areas, , l, , mRNA/DNA, mDNA/DNA, fragments, DNA probe, cDNA bank, DNA bank, Plant cell/, protoplast culture, , Cloning vector, (plasmid, cosmid, virus), , l, , Recombinant DNA, , Transformed cells, e.g. vaccines, interferon,, e.g. nif genes, antibiotics, chemicals,, stress and disease resistant super bugs, monoclonal, genes, other genes, antibodies, etc., , l, , l, , l, , Ligation, , Desired products, , l, , l, , Human globin genes has also been developed and, cloned., By using gene cloning techniques the clotting factor, VIII:C gene was cloned which expressed in, mammalian cell lines and produced the protein, VIII:C responsible for blood clotting., Recombinant DNA technology has helped in, increased production of antibiotics; for example,, the rate of penicillin produced at present is about, 1,50,000 unit/ml against about 10 unit/ml in 1950s., , l, , l, , l, , A genetically engineered bacteria is capable of, cleaning up oil spills., Organisms that have been genetically altered using, the techniques of genetic engineering are generally, referred to as transgenic., Transgenic salmon (a fish) is produced by inserting, recombinant growth hormone genes into developing, salmon embryos. They are 11 times heavier than, nontransgenic salmon., Weevilproof peas, herbicide resistant crops and, wiltproof flowers are produced by using genetic, engineering., Human enkephalin gene has been expressed in, plants thus producing medical drugs from crops, instead of food., Gene transfer during transgenic plant formation, includes (i) electroporation, (ii) particle, bombardment (iii) micro injection, (iv), Agrobacterium mediated gene transfer, (v) co, cultivation (protoplast transformation method), (vi), leaf disc transformation method, (vii) virus, mediated transformation, (viii) pollenmediated, transformation, (ix) liposome mediated, transformation etc., In 1999, the Indian scientist at ICGEB, New Delhi, have successfully produced transgenic maize,, tobacco, rice etc. capable of producing interferon, gamma (INFg).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– Őě– ▓ńďňŚř– ďňę– ►ŕŐő– ▀ŇőŕŐŢĚŇĚňŚ, , 589, , Chapter 65, , Domestication of Plants &, Crop Improvement, DOMESTICATION OF PLANTS, l, , l, , l, , l, , l, , l, l, l, , l, , l, , Domestication is a phenomenon whereby a wild, biological organism is habituated to survive in the, company of, or by the labour of, human beings., Domesticated animals, plants, and other organisms, are those whose collective behaviour, life cycle, or, physiology has been altered as a result of their, breeding and living conditions under careful human, control for multiple generations., Humans have brought these populations under, their care for beneficial uses. It may be to produce, food or valuable commodities (such as wool, cotton,, or silk), for help with various types of work,, transportation and to enjoy as pets or ornamental, plants., Plants domesticated primarily for aesthetic, enjoyment in and around the home are usually called, house plants or ornamentals, while those, domesticated for largescale food production are, generally called crops., All the present species of cultivated plants are of, wild species origin and this process of cultivation, of wild species in order to fulfil human needs is, called domesticaton of plants., Domestication plays foremost role in development, of human civilization., Effective agriculture is the result of domestication, of crop plants., Origin of agriculture dates back to 7000–13,000, years ago in high and well watered lands of Indus,, Tigris, Nile and Euphrates., According to Carl Scanner, nitrogen loving plants, were the first wild weed plants, which were then, brought under cultivation., Cultivation of plants started with the help of, , l, l, l, , l, , l, , l, l, , l, , l, , vegetative parts in the form of tubers, bulbs,, rhizomes, etc., but later on ability of seed to develop, into new plant was recognized and most of the, early civilizations like Babylonian, Egyptian, etc.,, developed on the basis of seedgenerated crops like, wheat, rice, maize, barley, etc. (cereals)., Actually, the method of obtaining plants from seeds,, is known as cultivation., The earliest human attempts at plant domestication, occurred in Asia., There is early evidence for conscious cultivation, and trait selection of plants by preNeolithic groups, in Syria: grains of rye with domestic traits have, been recovered from EpiPalaeolithic (ca. 11,000, BC) contexts at Abu Hureyra in Syria, but this, appears to be a localised phenomenon resulting, from cultivation of stands of wild rye, rather than, a definitive step towards domestication., By 10,000 BC the bottle gourd (Lagenaria, siceraria) plant, used as a preceramic technology, container, appears to have been domesticated., The domesticated bottle gourd reached the Americas, from Asia by 8000 BC, probably with peoples, migrating into the continent from Asia., Cereal crops were first domesticated around 9000, BC in the Fertile Crescent in the Middle East., Origin of cereals actually took place in montaineous, parts of both old world (Asia, Africa and Europe), and new world (America) and present day cereals, were infact wild weeds., Cereals were actually the first group of plants,, which were brought under domestication because, of rapid growth, sufficient amount of reserve food, and weediness., After direct food plants like cereals, plants with, cooking qualities were brought under cultivation.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 590, , l, l, , l, , l, , l, l, l, l, , l, , l, l, l, l, , l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Discovery of fire was an important reason behind it., So, now different other food plants like pulses, oil, seeds along with cereals were discovered and man, turned into actual farmer., The first domesticated crops were generally annuals, with large seeds or fruits. These included pulses, such as peas and grains such as wheat., The Middle East was especially suited to these, species; the drysummer climate was conducive to, the evolution of largeseeded annual plants, and, the variety of elevations led to a great variety of, species., Domestication was gradual, a process of trial and, error that occurred slowly., Over time perennials and small trees began to be, domesticated including apples and olives., In different parts of the world very different species, were domesticated., In the Americas squash, maize, and beans formed, the core of the diet. In East Asia millets, rice, and, soya were the most important crops., Some areas of the world such as Southern Africa,, Australia and California and southern South, America never saw local species domesticated., Over the millennia many domesticated species have, become utterly unlike their natural ancestors., Corn cobs are now dozens of times the size of their, wild ancestors., A similar change occurred between wild, strawberries and domesticated strawberries., After discovery of single purpose plants,, multipurpose plants were known and these brought, into cultivation, e.g., coconut, date palm, hemp,, mulberry, etc., Despite long enthusiasm about revolutionary, progress in farming, few crops became, domesticated., Domesticated species, when bred for tractability,, companionship or ornamentation rather than for, survival, can often fall prey to disease: several sub, species of apples., One sideeffect of domestication has been causing, of disease., Domestication of wild species is still being done, and is likely to continue for a long time in future., This is because the human needs are likely to change, with time., The wild species of little importance today may, , l, , assume great significance tomorrow. This is, particularly true for microorganisms producing, antibiotics, involved in nitrogenfixation and, producing timber and other commercial products,, medicinal plants., A notable case of recent domestication is that of, several members of Euphorbiaceae producing latex., The latex of these plants may be commercially used, for extraction of petroleum products including, petrol and diesel., , Origin of cultivated plants, l, , l, , l, , l, , l, l, , l, , l, , The earliest view of origin of cultivated plants is, that these plants are given by god in form of gifts., Later on it was said that wild types converted into, cultivated types due to their cultivation under good, agronomic conditions., Most important contribution made by a Russian, worker called N. I. Vavilov (1926), who on the, basis of his studies reported that there are eight, primary centres of origin of cultivated plants, where, all grades of variations from wild type species to, cultivated types occur., These primary centres are dominated by dominant, genes. In the course of cultivation, the plants spread, to different parts of the world., In some areas certain crop species show, considerable diversity to form although they did, not originate there. Such areas are known as, secondary centres of origin of these species., The centres of origin are also called the centres, of diversity., There are 8 main centres of origin as proposed, by Vavilov China, Hindustan, Central Asia, Asia, Minor, Mediterranean, Abyssinia, Central America, and South America., China – This centre consists of the mountainous, regions of Central and Western China and the, neighbouring low lands. It is the largest and the, oldest independent centre of origin. It is the, primary centre of origin for soyabean, radish,, opium, poppy, brinjal, pears, peaches, plums,, oranges and chinese tea and secondary centre of, origin for maize, rajma, cowpea and sesame., Hindustan – This includes Burma, Assam, Jalaya,, Java, Sumatra and Phillipines but excludes North, Western India and NorthWestern Frontier, provinces. It is the primary centre of origin for
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– Őě– ▓ńďňŚř– ďňę– ►ŕŐő– ▀ŇőŕŐŢĚŇĚňŚ, , l, , l, , l, , l, , l, , l, , rice, pulses (arhar, gram, cowpea, mung),, cucumber, nobel canes (Saccharum officinarum),, cotton, mango and banana., Central Asia – It includes NorthWestern India,, whole of Afganistan, Tazakistan and Uzebekistan., It is the primary centre of origin for wheat, pea,, linseed, sesame, onion, garlic, spinach and grape, and the secondary centre of origin for rye., Asia Minor – It is also known as Near East Centre, of origin and includes interior of Asia Minor, whole, of Iran and high lands of Turkmenistan. It is the, primary centre of origin for rye, alfa alfa, carrot,, oat, fig, pomegranate, apple and nuts. and the, secondary centre of origin for rape (Brassica, campestris) and black mustard (B. nigra)., Mediterrean – It is the primary centre of origin, for durum wheat, emmer wheat, barley, lentil,, several species of Lathyrus, pea, beets, lettuce,, onion, garlic and cloves., Abyssinia – It includes Ethopia and Eritrica. It is, the primary centre of origin for jowar, bajra,, sem, safflower, castor, linseed and coffee and, secondary centre of origin for broad bean., Central America – It includes both Mexico and, Central America. It is the primary centre of origin, for maize, cotton, rajma, pumpkin, papaya,, guava and avacado., South America – It includes high mountain regions, of Peru, Bolivia, Eucador, Colombia, parts of Chile, and Brazil and whole of Paraguay. It is primary, centre of origin for tomato, potato, tobacco,, groundnut, rubber and pineapple., , Degrees of domestication, l, , l, l, , l, , A classification system that can help solve the, confusion might be set up on a spectrum of, increasing domestication., Wild – These species experience their full life cycles, without deliberate human intervention., Raised at zoos or botanical gardens – These, species are nurtured and sometimes bred under, human control, but remain as a group essentially, indistinguishable in appearance or behaviour from, their wild counterparts. (It should be noted that, botanical gardens sometimes exhibit domesticated, plants such as some orchids)., Domesticated – These species or varieties are bred, and raised under human control for many, generations and are substantially altered as a group, in appearance or behaviour., , l, , l, l, , 591, , This classification system does not account for, several complicating factors as genetically modified, organisms, feral populations, and hybridization., Many species that are farmed or ranched are now, being genetically modified., This creates a unique category because it alters the, organisms as a group but in ways unlike traditional, domestication., , Natural and artifical selection under, domestication, l, , l, , l, , l, , l, , Selection may be described as the phenomenon in, which some genotypes from a population leave, behind more progeny than the others., In nature, there is a continuous selection by natural, forces, eg., temperature, soil, moisture, pests,, diseases, etc., The genotypes more suited to a given environment, leaves behind more progeny than the less adapted, ones. This process is known as natural selection., The artificial selection (selection by man) often, permits only the selected plants to reproduce. Thus,, man exerted considerable selection on the, domesticated plant species., Artificial and natural selection have led to several distinct, changes in characteristics of domesticated species., , Changes under domestication, l, , Some important changes that have occurred under, domestication are enumerated as –, –, Reduction in shattering of pods, spikes, etc., –, Elimination of dormancy in several crop species., –, Decrease in toxins or other undesirable, substances., –, Cultivated plants show altered tillering,, branching, leaf characters, etc., –, Decrease in plant height as in the case of, cereals and millets., –, Increase in plant heights as in the case of jute,, sugarcane and forage grasses., –, Reduction in life cycle as in the case of cotton, and arhar., –, Increase in fruit and grain size., –, Promotion of sexual reproduction as in the, case of sugarcane, potato, sweet potato, etc., –, Variability within a variety has drastically, decreased under domestication (a negative, effect)., –, Preference for polyploidy, for instance, potato,, wheat, sweet potato, tobacco, etc. while,, diploid plants are present in nature.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 592, , ŕďőĽę– ĐĽŐńŐĹť, , CROP IMPROVEMENT, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , Crop improvement proposes to obtain crops with, higher yield, better quality, resistance to disease, and shorter duration which are suitable to, particular environmental conditions., It involves two types of measures – improved, agricultural preparation and improvement of, crop varieties., Agricultural preparation includes, application of, manures and fertilizers, protection against diseases, and pests, proper irrigation, improved reaping,, transport and storage of products., Improvement of crop varieties is a permanent, measures which creates genetic potentiality in crop, plants for higher and better yield., Genetic improvement of crops, along with the, control of important diseases of crops, are very, useful in increasing food production and food, quality., Scientists connected with improvement of crop, varieties are called plant breeders., Plant breeding is an applied branch of botany and, deals with the improvement of cultivated varieties, (cultivars) of plants., It is the improvement in the heredity of crops and, production of new crop varieties which are far better, than original types in all respects., The aims of plant breeding differ with the type, of crop, soil, climate, etc. However, some common, objectives are listed below –, –, To get higher yield., –, To improve the quality, size, shape, colour,, taste and storability (keeping quality) of the, produce., –, To improve resistance to drought, diseases,, frost, salinity etc., –, To prevent the premature falling of buds, fruits etc., –, To change the duration of the crop i.e., to, develop early maturing (short duration) or late, maturing (long duration) crops., –, To increase the efficiency of use of fertilizer., –, To change the growth habit i.e., to produce, dwarf or long varieties, profusely branched or, sparsely branched varieties., –, To make harvesting easier., –, To induce the adaptability of a crop to different, climatic and soil conditions., A cultivated variety having majority of the above, characters is regarded as a superior variety., , Methods of plant breeding, There are different methods of plant breeding., They are – introduction, selection, hybridization,, mutation breeding, polyploidy breeding, tissue, culture, and genetic engineering., Different methods of breeding are based on the, type of reproduction and pollination operating in, a crop., , l, , l, , Plant introduction, l, It is the process of introduction of high yielding, varieties of plants from their growing locality to, another, with changed climatic condition., l, Acclimatization is the adaptation of introduced, plant in the changed environment., l, Uncontrolled plant introduction in the past are, res ponsible for in trodu ction of h azard ous, diseases (like late blight of potato, flag smut of, wheat, leaf rust of coffee, fire blight of apple, and pear)., l, l, , l, l, l, l, , l, l, l, l, l, l, , Indian Plant Breeders, Sir. T.S. Venkatraman – Pioneer Indian Plant, breeder famous for sugarcane improvement., Choudhary Ram Dhan – Wheat breeder, who is, famous for C591 variety of wheat, which made, Punjab as wheat granary of India., Dr. B.P. Pal – Famous wheat breeder, who produced, many NP wheat varieties., Dr. K. Ramiah – Famous rice breeder of, international fame., Dr. Pushkar Nath – Famous potato breeder., Dr. Boshi Sen – Famous maize breeder., Historical Account, As early as 700 BC, Assyrians and Babylonians, used to cross pollinate date palms artificially., In 1694 Camararius proved that there is sexual, differentiation in plants., In 1717, Thomas Fairchild produced the first hybrid, plant artificially., In 1761, Cotton Mather recognized the process of, natural selection in maize., During 170666 Joseph Koelreuter produced many, hybrids in tobacco., During 19th and 20th centuries, techniques of plant, breeding like, selection, hybridization, were, improved. L.L. Vilmorin (France), Burbank (USA),, Michurin (USSR) are some of the famous plant, breeder of that time.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– Őě– ▓ńďňŚř– ďňę– ►ŕŐő– ▀ŇőŕŐŢĚŇĚňŚ–, l, , l, , l, , l, , l, , l, , But achievements of plant introduction are also, numerous, eg., new plants like maize, potato,, groundnut, chillies, coffee etc. are the result of, plant introductions., Similarly, many improved varieties of different crop, plants are also outcome of these introduction, eg.,, Ridley and Sonora – 64 varieties of wheat., Quarantine is careful examination of all the, introductions for the presence of weeds, insects,, and diseasecausing organisms. This is because with, every introduction of new variety of a species, there, are also chances of coming new weeds, insect pests, and diseases from other countries. Quarantine is, also applied to animals and, sometimes, to humans, to reduce the risk of entry of a pathogen in the, country., The progeny produced by crossing two varieties,, species or genera having desired genes and, bringing together the useful character in it is called, hybrid., Introduced plants serve as a good source of, parental material for hybridization experiments., Introduced plants can be subjected to “selection”, to get better results., Plants pathogens and pests may also seek entry, along with the introduced plant material. They may, multiply rapidly in the new climate and cause, serious damage to the introduced variety. For, example, pathogens like Phytophthora infestans, (late blight of potato) from Europe (1883), Hemileia, vastatrix (coffee rust) from Ceylon (1876),, Urocystis tritici (flag smut of wheat) from Australia, were introduced into India., , Selection, l, Selection is the oldest breeding method. It is of, two types – natural and artificial., l, Natural selection is a natural process. Evolution, is the ultimate result of natural selection only., According to the Darwin’s principle – “Survival of, the fittest”, plants which survive through the, adversities of nature are preferred and the weaker, ones are wiped out. Thus, nature itself selects the, fittest organisms., l, In artificial selection the selecting agent is man., Man exploits the variations existing among the, species. He picks up a few plants of better qualities, from mixed populations and tries to propagate them., l, There are three methods of artificial selection–, , l, , l, , l, , l, , l, , l, , l, , l, , l, , 593, , mass selection, pureline selection, and clonal, selection., Mass selection is the simplest and the oldest, method of crop improvement practised by, farmers. It is practised in cross pollinated crops., Plants are in heterozygous condition. Seeds of best, plants, showing high vigour are collected and, pooled up. These seeds are used to raise the crop, in the next year., The same process is carried out for 7 or 8, generations. Finally they will be multiplied and, distributed to the farmers for cultivation., Good results are obtained if the existing variations, are more in the population. Mass selection is based, on external characters (phenotype) only. Hence it, is easy to follow this., Merits of mass selection are –, –, It is the easiest and quickest method of crop, improvement., –, It needs no scientific knowledge., –, The newly produced variety need not be tested., –, Pollination need not be controlled to produce, a new variety., –, Mass selection is the only method of, improving wild or local varieties., Demerits of this process are –, –, Importance is given to phenotypic characters, only., –, This method is applicable only to cross, pollinated crop., –, The new variety produced is always, heterozygous., –, There is no control over pollination as a result, the degree of heterozygosity increases and the, desirable qualities gradually diminish., –, It is not possible to increase the yield of a, variety because importance is given to, maternal characters only and yield is subjected, to environmental influences., A pure line may be defined as the “progeny of a, single individual obtained by selfing” – Sinnot et, al., A group of plants obtained from a single self, fertilized homozygous plant is called a pure line., The term pure line was first introduced by W.L., Johannsen in 1903., This method is mostly applicable to self pollinated, crops. The progeny of a pure line selection are
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 594, , l, , l, , l, , l, l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , similar phenotypically and genotypically., Sometimes minor variations may occur in a pure, line. These variations are simply due to the influence, of environment., 50100 plants or heads are selected from the mixed, population of the field before harvest and seeds, are collected separately., The progeny of each such plant are grown in a, separate line. Plants with desirable characters are, selected from each line again. 2550 seeds from, such plants will be grown in separate rows in a, plot., The same process is followed for 7 to 8 generations, until a new variety is isolated., Merits of pure line selection are –, –, This is the only method to improve local, varieties of self pollinated crops., –, This method is easier than hybridization., –, New plant varieties produced by this method, are uniform, similar in phenotype and, genotype., –, This method is also useful for the production, of pure lines and inbred lines in cross, pollinated crops., Demerits of this method are –, –, It is a very lengthy and laborious process., –, New characters (new genotypes) cannot be, introduced into a plant variety., –, It is not possible to improve a variety beyond, a certain level of homozygosity., –, Extreme homozygosity may result in low yield, and other undesirable characters., –, Due to high degree of homozygosity,, variations among the varieties are also limited., Therefore, their adaptability to varied, conditions is also poor., Selection of desirable clones from the mixed, population of a vegetatively propagated crop is, called clonal selection., The progeny of a single plant obtained by vegetative, propagation is known as a clone or all the vegetative, progenies of a single plant are called a clone., Clonal selection is a method of improving, vegetatively propagated crops such as sugarcane,, banana, potato, citrus, mango, grapes, sugar beet, etc. All the plants of a clone are similar in phenotype, and genotype. Just like in pureline selection, here, also, importance is given to the phenotype only., , l, , l, , Merits of clonal section are –, –, Varieties developed by clonal selection are, more stable., –, As there is no segregation, variations do not, usually appear., –, Even after many years of cultivation, the, characters are not disturbed or lost., –, Hybrid vigour of a plant can be maintained or, preserved for many generations by clonal, selection., –, This is the only method to improve the, vegetatively propagated crops improved by, hybridization which are also finally selected, by this method., Demerits of this method are –, –, This method is not applicable to crops, propagated by seeds., –, This method is useful only to isolate best, genotypes already present in the populations., –, New genotypes cannot be developed by this, method., , Hybridization, l, Hybridization can be defined as mating between, two (or more) individuals or lines differing in, genotype. It is the most common method of, creating genetic variation., l, The technique of hybridisation involves crossing, two plants to get a new synthetic one possessing, the combination of good qualities of the parental, plants. Hybridisation is often done in green house, under controlled conditions., l, The process of hybridisation involves following, steps –, –, Selection of parents: An individual /lines used, in hybridization are called parents., –, Selfing of parents to induce homozygosity., –, Emasculation: If the two parents have, bisexual flowers, before the flowers of female, parent open and shed pollen, their anthers are, carefully removed. This is called emasculation., –, Bagging: This is the process by which male, and female plants are kept in isolation by, enclosing them in bag., –, Pollination: Pollen is then collected from the, flowers of male parent and placed on the, stigma of flowers of female parent. The seeds, produced by these flowers of female parent, are the hybrid or F1 seeds.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– Őě– ▓ńďňŚř– ďňę– ►ŕŐő– ▀ŇőŕŐŢĚŇĚňŚ–, l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , Hybridization or crossing leads to hybrid vigour, or heterosis, which is defined as “superiority of, hybrid over its parents”. Selfing results in, inbreeding., The term heterosis was given by G.H. Shull in, 1914 (Heteros different; Osis Condition), i.e.,, different condition of hybrid from its parents., Hybrid vigour has been commercially exploited in, different commercial crops like maize, sorghum,, bajra, tomato, sugarbeet, petunia, zinnia and, cucumbers., Heterosis is used in genetics & breeding. It is the, possibility to obtain a “better” individual by, combining the virtues of its parents. Heterosis is, often the opposite process of inbreeding depression, which increases homozygosity., Effect of Heterosis – Heterosis does not affect an, individual as a whole but only in separate parts, such as root in carrot, tuber in potato, hypocotyl in, turnip, flower in cauliflower/fruits in pea, lobia,, bhindi and curcurbits etc. The effects of heterosis, in these plants can be expressed in the following, ways – greater height, weight, size and number of, the different parts of the plants, increase in yield, and growth, greater fertility and viability, more, efficient seed germination, longivity, earlier, flowering and maturity, and increased resistance to, disease., Importance of heterosis – This phenomenon, results in hybrids that have better characters. Many, ornamentals and fruit trees, valuable vegetables,, good quality cereals are results of cross breeding, inbreeds., Besides plant breeding, heterosis is also practicable, in animal breeding., When the offsprings are produced by self, fertilization or breeding between closely related, parents it is called inbreeding. It is a form of mating, system in a sexual organisms., Thus, selffertilization or selfing is an extreme form, of inbreeding. Inbreeding results in increase in, homozygosity., The most revealing impact of inbreeding is the loss, of vigour and physiological efficiency of the, organisms characterized by reduction in size., A number of lethal and defective characters appear, , 595, , in the population which has undergone inbreeding, (selfing). “This loss of fitness in the progenies or, decline in character expression with decreased, heterozygosity arising from self mating is known, as inbreeding depression or inbreeding decline., l, Haldane (1948) referred inbreeding to be – “the, enemy of vigour and yield of plant”., l, The effects of inbreeding are of great importance, in plant breeding and are given below as –, –, Inbreeding tends to increase the genetic, correlation between relatives. It determines, the success of pure line inbreeding for, improvement of self pollinated crops., –, Since inbreeding split the population into, genetically divergent families with little, additive variation at intrafamily level but, ample at interfamily level, selection is, effective only between family., –, Inbreeding is useful for progeny testing since, close inbreeding (selfing) is the only effective, method of differentiating heritable differences, from nonheritable differences (characters)., –, Inbreeding is used to develop inbreeds in, crosspollinated crops., Mutation breeding, l, Hugo de Vries was the first person who defined, “mutation as sudden phenotypic changes which, are heritable”. When mutated plants are used in, plant breeding, new varieties of crops are produced., l, Sharbati Sonora and Pusa lerma are the two, important varieties of wheat produced by gamma, rays treatment of Sonora 64 and Lerma Roja 64, (Mexican dwarf wheat varieties)., l, Sharbati Sonora is the amber grain coloured variety, of wheat produced by Dr. M.S. Swaminathan and, is responsible for green revolution in India., l, In rice, about 45 varieties upto 1992 have been, produced by mutation breeding. Important ones are, Remei variety and Atomita 2., l, Mutation breeding has some important, limitations as –, –, Most of the induced mutations are invaluable, to the breeders and many of them are lethal., –, Mutation rate is extremely low., –, Stability of mutants is sometimes doubtful as, some mutants have tendency to revert back to, original type., –, Most of the mutations are recessive.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 596, , –, , ŕďőĽę– ĐĽŐńŐĹť, , The main uses fall in 3 categories – genic, manipulations, chromosomal engineering and, diffusing specific plant breeding problem., , Polyploid breeding, l, The organism (plant) which contains more than, two complete sets of chromosomes, is called, polyploid., l, Depending upon the number of chromosomal sets,, the individuals are given different names as , monoploids, diploids, triploids, tetraploids,, pentaploids and hexaploids (eg., wheat)., l, Polyploids are characterized by gigantism or, increase in cell size and hence organ size and thus, overall size. These polyploids are used in crops, improvement, eg., triploids are present naturally, in different crop plants and generally in triploids,, seedlessness is present., l, Most of the varieties of banana are triploids and, hence their fruits are seedless., l, These triploids are not of any use in such plants, where seeds are of commercial importance., l, Polyploidy can also be induced artificially by, colchicine treatment. Colchicine is an alkaloid, obtained from Colchicum autumnale (Liliaceae)., Tissue culture, l, This is one of the latest and most promising methods, of crop improvement in such plants, where all other, conventional methods of breeding fail., l, Tissue culture technique is based on totipotent, nature of plant cell or phenomenon of, totipotency, i.e, each and every plant cell has, inherent capacity to develop into complete plant, [For more detail refer chapter ‘Plant Tissue Culture’]., , l, , Genetic engineering, l, This is the latest method of crop improvement in, which instead of involving whole chromosomal set, (genome), manipulation of a segment of DNA, (gene) is done., l, In this technique, introduction or deletion of one, or more genes is done into an organism or plant., [For more refer chapter Biotechnology & Genetic, Engineering ]., , l, , Green revolution, l, Green revolution is rapid increase in agricultural, output as witnessed in India during 1970s., l, It has been achieved through introduction of high, yielding varieties, increased irrigation facilities,, , l, , l, , l, , fertilizer application, weed, pest and pathogen, control, multiple cropping and better agricultural, managment., N.E. Borlaug – Famous Mexican plant breeder,, who was awarded Nobel Peace Prize (1970) for, developing high yielding dwarf wheat varieties like, Norin10, Sonora64, Lerma rojo64, etc. He is, known as “Father of green revolution”., Dr. M.S. Swaminathan – He is pioneer mutation, breeder. He has produced Sharbati Sonora, a variety, of wheat by mutation, which is responsible for green, revolution in India. Dr. Swaminathan is called, ‘Father of green revolution in India”., Dwarf Rice – A dwarfing gene, deegeowoogen,, was noted in Taiwan. It was introduced in Rice, varieties (IR8, IR24) by IRRI. Philippines., To check Grassy stunt virus, Dr. Gurudev S. Khush, crossed 13 rice varieties from six countries and, Oryza nivara (Wild Rice from Central India) to, produce early maturing, high yielding and resistant, variety IR36., , Transgenic crops/plants, l, , l, , l, , l, , l, , The most important use of plant biotechnology is, the production of superior transgenic crops/plants, which are having not only the resistance against a, variety of biotic and abiotic stress, but also having, some improved value added properties like, nutritional quality of food., Transgenic plants are those plants in which a, foreign gene has been introduced and stably, integrated into host DNA., A gene that has been transferred using the tools of, molecular biology is called transgene., The first transgenic plants are produced in tobacco, (Nicotiana tabacum). Some other higher plants, where transgenic plants have been produced are, Lycopersicum esculentum (tomato), Solanum, melongena (brinjal), Vitis vinifera (grapes), Zea, mays (maize), Avena Sativa (oat) etc., India has permitted the commercial cultivation of, three varieties of BtCotton, the first genetically, modified crop of the country. This has been, developed by MAHYCO (Maharashtra Hybrid, Seeds Company) in collaboration with American, company Monsanto. BtCotton is resistant to Boll, worm disease of cotton., Nowadays, there is a debate on biosafety issues of, transgenic plants. The key points are –
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– Őě– ▓ńďňŚř– ďňę– ►ŕŐő– ▀ŇőŕŐŢĚŇĚňŚ, , –, –, , l, , l, , Potential of GM crops to become weeds., Opportunities of gene flow from a GM plant, to other plants., –, Impact of growing transgenic plants on, biodiversity., –, Capacity of pests and pathogens to adapt to, the cultivation of GM crops., The area under transgenic crops will continue to, rise and thus will result in more food derived from, transgenic crops are called “GM foods” or, genetically modified foods., The main concerns about the potential of GM foods/, crops relate to –, –, Increase in toxins., –, Introduction to allergens., –, Changes in the levels of essential nutrients., –, Reduced efficacy of antibiotics., , l, , l, , l, , Social forestry, l, , l, , l, , Social forestry is raising of fast growing and, multipurpose species of trees and shrubs by local, people on public and common vacant lands and, roadsides etc for fulfilling their fodder, fuel and, small timber requirement., The species of plants selected for social forestry, vary from one locality to another. It reduces the, pressure on real forests and also manages soil and, water conservation, saves dung for manure and, biogas and moderates climatic conditions., Important plants recommended for social, forestry programme are – Dalbergia sisso,, Moringa, Morus, Tectona, Zizypus etc., , l, , l, , New and under utilized crops, l, , l, , l, l, , Out of about 3,50,000 known plants at this time,, a few, i.e, about 100 plants are being used for, fulfilling man’s daily requirements., Scientists are in search of less known and under, utilized crop plants, which can be used for food, and other purposes and thus exploitation of, traditional plants can be reduced., Such underutilized and under exploited plants are, known as new crops., Triticale is the first man made cereal or crop,, which has been produced by intergeneric, hybridization between common wheat (Triticum, aestivum) and European rye (Secale cereale) with, a view to combine characters of these two parents, plants., , l, , 597, , Guayule [Parthenium argentatum (Fam, Asteraceae), commonly known as carrot grass or, congress grass] – This is native of America and, nowadays it is most troublesome terrestrial weed, in India and is present in almost all states of India., The roots of this plant secrete transcinnamic acid,, which inhibits the growth of other plants, (allelopathy). This is shrub and can grow on poor, desert soils., Subabul or Leucaena [Leucaena leucocephala, (Famleguminosae)] is a fast growing small tree, and is native of Central America. This plant is, nowadays being planted on a large scale under social, forestry. These plants are used as wind breaks, fire, breaks, wood as fuel timber etc., Jojoba (Simmondsia chinensis) is a shrub, which, is native of Mexican deserts. It is important drought, desert plant and hence is being grown in deserts., The seeds of this plants contain about 50% liquid, wax, which is similar to sperms whale oil, (spermaceti). This liquid wax was originally used, in cosmetics, but now is also being used in high, performance lubricants., Winged bean [Psophocarpus tetragonolobus, (Fam leguminosae)] is a herbaceous plant, which, has capacity of nitrogen fixation. This plant can be, used as a green manure plant, fodder plant and also, as a cover crop., Some potential oil yielding plants are there, which, provide edible and nonedible oils after suitable, treatments. They are – Margosa or Neem, Mahua,, Sal, Mustard tree etc., Fodder trees includes Acacia nilotica (Kikar or, Babul), Albizzia lebbeck (Siris), Ficus religiosa, (Peepal), Morus alba (white mulberry) etc., , Conservation of genetic resources, l, , l, , It is the conservation of genetic diversities present, in different varieties of a species and related species, which are likely to be required for improvement of, existing crop plants., FAO (Food and Agricultural Organisation of UNO), established an International Board for plant Genetic, Resources in 1971 with several centres. Two of, them are –, –, IRRI – International Rice Research Institute,, Los Banos, Philippines., –, ICRISAT – International Crops Research
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 598, , ŕďőĽę– ĐĽŐńŐĹť, , Institute for SemiArid Tropics, Hyderabad,, India conserving germplasm of groundnut,, pigeon pea, chick pea, pearl millet and, sorghum., Exsitu conservation, l, It is conservation of selected rare plants/animals in, places outside their natural homes., l, Exsitu conservation includes offsite collections and, gene banks but it is often restricted to channeling, the selected organisms into trade for nature lovers,, agriculturists and horticulturists., l, Ginkgo biloba (ginkgo tree), once in the list of, endangered species is now flourishing in gardens., In situ conservation, l, It is maintanance of biological diversity in natural, habitats like forests and nature preserves by setting, national parks, wildlife sanctuaries and biosphere, reserves., Gene banks, l, For plant breeding purpose (i.e., for improvement, of plants), large number of varieties with different, characters are needed., l, Hence number of plants (both wild and cultivated), are collected and stored at suitable place., l, The place or institution where different plant, material (genes) are kept or preserved, is called a, gene bank. In gene bank, storage is done either in, the form of seeds or vegetative materials, but best, and convienent way is storage of seeds., l, Storage of dry seeds is done at low temperature, (–10 to – 20º C), because under these conditions,, their metabolic activities are minimum which, check their germination., l, Seeds are of two types – orthodox seeds and, recalcitrant seeds., l, Orthodox seeds are those which are not killed or, damaged as a result of decrease in moisture contents, and temperature., , l, , l, , l, l, , These can even live upto – 196ºC, eg., seeds of, wheat, rice, maize, oat, barley (cereals) and also, different pulses or legumes., Recalcitrant seeds are those which are killed or, damaged as a result of drying and decrease in, temperature., These can be stored for a short span, eg., seeds of, rubber, tea, coconut, jack fruit, litchi, oil palms etc., Conservation of crops with these types of seeds, can be made by Insitu conservation method and, also by tissue culture method., , GENETIC EROSION, l, , l, l, l, , Genetic erosion is the appearance of genes/alleles, from the gene pool and reduction in the genetic, resources of the earth., 20th century has seen a loss of 75% genetic diversity, of crop plants., By 1990 high yielding varieties had occupied more, than 50% areas of wheat and rice lands., Genetic erosion occurs due to –, –, Deforestation – It not only reduces natural, population of plants and animals but also, causes disappearance of many species., –, Crop number – Originally a large number, of plants were exploited for different uses, but slowly the number of exploitable plants, have decreased. For example, out of 3000, food plant sp ecies, only 150 were, commercialised. Agriculture is dominated by, only 12 species out of which four yield more, than 50% of the total (rice, wheat, maize,, potato)., –, Crop varieties – There is a tendency to, incorporate the maximum good qualities in a, single variety. As soon as a better variety is, developed, the same is distributed far and, wide. The older varieties are discarded and, their specific alleles lost for ever.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ♀ĽřřśĚ– ►śńŚśŕĚ, , 599, , Chapter 66, , Plant Tissue Culture, l, , l, , l, l, , l, , l, , l, , l, , l, , Previously genes could be transferred only through, hybridisation/breeding activity usually carried out, in the field., In later half of 20th century techniques were, developed which could transfer genes from any, source., The phenomenon is called recombinant DNA, technology/Genetic engineering., During the later half of the twentieth century,, scientists made great strides to synthesize a plant, in the laboratory from single cell, tissue or organ, grown in nutrient medium in glass containers under, specific conditions., The cultures of microbes are used in recombinant, DNA technology and in variety of industrial, processes while cultures of plant cells and tissues, are used for variety of gene manipulation., Plant tissue culture is one of the latest and most, promising methods of crop improvement in such, plants where all other conventional methods of, breeding fail., Plant tissue culture can be defined as the, maintenance and growth of plant cells, tissues, and organs on a suitable culture medium in vitro, (in a test tube). Plant tissue culture is dependent on, specialized laboratory facilities and technical skill., Plant tissue culture, also called micropropagation,, is a practice used to propagate plants under, sterile conditions, often to produce clones of a, plant., Different techniques in plant tissue culture may, offer certain advantages over traditional methods, of propagation. Like –, –, The production of exact copies of plants that, produce particularly good flowers, fruits, or, have other desirable traits., –, To quickly produce mature plants., , –, , l, l, , l, l, , l, , The production of multiples of plants in the, absence of seeds or necessary pollinators to, produce seeds., –, The regeneration of whole plants from plant, cells that have been genetically modified., –, The production of plants in sterile containers, that allows them to be moved with greatly, reduced chances of transmitting diseases,, pests, and pathogens., –, The production of plants from seeds that, otherwise have very low chances of, germinating and growing, i.e., orchids and, Nepenthes., –, To clean particular plant of viral and other, infections and to quickly multiply these plants, as ‘cleaned stock’ for horticulture and, agriculture., The plant part which is cultured is called explant., Explant is excised from its original location and, used for initiating a culture. The explants may be, root, stem, shoot tip, leaf petiole, embryo etc. The, growth regulators or hormones are required for cell, division and organ regeneration from the cultures., The ability of plant cells to regenerate into complete, plants is called totipotency., Regeneration is the development of an organized, structure, like root, shoot or somatic embryo from, cultured cells., Gottlieb Haberlandt started the technique of, plant tissue culture in 1902., , TECHNIQUES OF PLANT TISSUE, CULTURE, l, , l, , There are three important aspects of in vitro, culture, namely nutrient medium, maintenance, of aseptic conditions and aeration of the tissue., Nutrient medium – Culture medium should
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 600, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , provide the nutrition that is required for the desired, growth and development of the explants. Standard, media are available for most purposes. These media, contain –, –, Inorganic salts of major and minor elements, –, Vitamins, –, Sucrose (as a source of carbon and energy), –, Growth regulators such as auxins (2,4, dichlorophenoxyacetic acid) and cytokinins, (e.g., benzylaminopurine)., Tissue culture can be maintained in a solid medium, or a liquid medium. Solid media are particularly, suitable for callus culture., Callus culture are prepared by mixing the liquid, nutrient solution with gelling agent (usually agar), at a concentration of about 12%. It also contains, the auxin 2, 4D, and a cytokinin like BAP., Liquid media or suspension culture may be placed, in test tube, stoppered by a plug of cotton wool or, a metal cap. Adding a small quantity of cells to the, medium is called inoculation. After inoculation,, the medium is kept in incubator at the optimum, growth temperature. Liquid medium usually, contains the auxin 2,4D., Aseptic conditions ( germ free conditions ) are, maintained by preventing entry and growth of, microbes, which can compete with growing tissue, and finally kill it., There are three main sources of contamination, of the medium –, –, The vessels, media(solutions) and instruments, should be treated with steam, dry heat or, alcohol, or subjected to filtration to make them, free from microbes. This process is called as, sterilization., –, Microbes may be carried along with the tissue, that is being cultured. The explants are, therefore, treated with specific antimicrobial, chemicals; this procedure is called surface, sterilization., –, Precaution should be taken to prevent entry, of microbes during the culture experiment., The chamber used for culture is sterilized with, ultraviolet light., Aeration of growing tissue is necessary to provide, air to the developing callus. It is achieved by, occasionally stirring the medium by stirrers or by, automatic shaker., , l, , l, , l, , l, , l, , l, , l, , l, , Plant tissue cultures are classified according to the –, –, Type of in vitro growth, viz., callus and, suspension cultures, –, Type of explant used for culture initiation,, e.g., embryo culture, anther culture, etc., In callus culture, cell division in the explant forms, a callus. Callus is an unorganised mass of cells., It is maintained on gel medium usually with agar., When an explant is placed on such a medium, many, of the cells become meristematic and begin to divide., Suspension culture grows much faster than, callus culture. Suspension culture consists of, single cells and small group of cells suspended, in a liquid medium. This culture must be, constantly agitated at 100200 rpm (revolutions, per minute)., Agitation serves the following three purposes –, –, Aeration of culture, –, Constant mixing of the medium, –, Breakage of cell aggregates into smaller cell, groups., Suspension cultures can be maintained in any of, two forms –, –, Batch culture – It is initiated as single cells, in a flask which are propagated by transferring, regularly small groups of suspensions to a fresh, medium., –, Continuous culture – It is maintained in a, steady state for long period by draining out, the used medium and adding fresh medium., The following three things happen in all type of, plant tissue cultures –, –, Cell/tissue dry matter (biomass) increases, –, The level of nutrients in the medium decreases, –, The medium volume declines due to, evaporation., If tissue cultures are kept in the same culture vessel,, they will die in due course of time. For this, cells, or tissues are regularly transferred into new, culture vessels containing fresh media. This, process is known as subculturing., Plantlets can be obtained from cultured cells by, two different ways –, –, Shoot regeneration followed by rooting of, the shoots, –, Somatic embryo regeneration followed by, their germination.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 601, , ▓ńďňŚ– ♀ĽřřśĚ– ►śńŚśŕĚ–, Explant, , Type of Explant, , Explants cultured, on agar medium, , Explants cultured, in, , Callus, (callus culture), , Suspension of cells, (suspension culture), Regeneration, , Shoot, Rooting, , Anther, , Protoplasts, , Callus, , Embryo, , Shoot, , Germination, , l, , l, , Germination, , Established in the field, B, , Shoot regeneration is promoted by a cytokinin like, BAP while root regeneration is promoted by an, auxin like NAA (naphthalene acetic acid). In fact,, shoot and root regenerations are basically controlled, by auxincytokinin balance., –, Cytokinin (BAP) ® promotes shoot, regeneration, –, Auxin ( e.g., NAA) ® promotes root, regeneration, –, High Cytokinin/Auxin ratio ® develops, shoots only, –, Low Cytokinin/Auxin ratio ® develops roots, only, –, Intermediate Cytokinin/Auxin ratio ®, develops shoots as well as roots., –, Intermediate Cytokinin/low Auxin ratio ®, continued growth as callus., Soma tic emb ryo reg en era tion is in d uced, usually by a relatively high concentration of, an auxin, such as 2,4D. These young embryos, develop into mature embryos either on the same, med ium or on the other medium. Mature, somatic embryos germinate and yield complete, plantlets., One can use different type of explant for culture, initiation, like meristems, anthers, protoplast,, embryo etc., , Meristem culture, l, , Plantlets, , Somatic hybrid, plantlets, Hardening, , l, , Explants containing, pre existing meristems, (shoot tips/nodal), , Plantlet, (embryo culture) Multiple shoots, (meristem), , Haploid Somatic hybrid cells, , Somatic embryo, , Plantlet, Hardening, Established in the field, A, , Young, embryos, , Explants that contain preexisting shoot meristems, , l, l, , Fig. A flow chart showing the, various types of plant tissue culture, and recovery of complete plants, from them. A : Callus and, suspension culture B : Anther,, protoplast, embryo and shoot type., , and produce shoots from them are used in meristem, culture., Shoot tips and nodal segments containing axillary, buds are commonly used in meristem culture., They are raised in cytokinin (eg., BAP) rich, medium. Cytokinin promotes formation of axillary, buds (it overcomes apical dominance). Therefore,, multiple shoots are formed. The technique is, therefore also called multiple shoot culture., Nodal explant, multiple shoots, (axillary branching), , l, , single shoot, (no axillary branching), , nodal segment, individual shoot, Meristem cultures can be used for –, –, Rapid clonal multiplication, –, Production of virus free plants, –, Germplasm conservation, –, Production of transgenic plants., , Anther culture, l, , The technique was developed by Guha and, Maheshwari (1964). It is highly useful for, immediate expression of mutations and quick, formation of pure lines. Very young unopened floral, buds are first sterilised in clorox (common bleach), for 10 – 20 minutes. They are then opened to remove, anthers. Anthers are introduced over culture, medium.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 602, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , When anthers, are used for culture in suitable, medium they produce haploid individuals. This, is called anther culture., The plants produced through anther culture are, homozygous. In many species, the pollen grains, can be isolated and cultured to obtain haploids., Haploids are important because they are used to, produce homozygous lines in 23 years. The, progeny from homozygous plants are subjected to, selection to isolate superior homozygous lines. This, approach has been successfully used to develop, several varieties., Year 1(Field), , l, , l, , Parent 1 × Parent 2, aa, AA, , Year 2 (Greenhouse), Tissue culture, laboratory, , A, , Year 2, (Greenhouse), , A, , Year 2, (Greenhouse), , AA, , F1 hybrid Aa, , Meiosis, a, anther culture, , Haploid plants a, aa, , Somatic hybridization, l, , l, , A hybrid produced by fusion of somatic cells of, two varieties or species is called somatic hybrid, and the process of producing somatic hybrids is, known as somatic hybridization., The somatic hybridisation helps in transfer of, desirable characters from wild or unrelated crop, species to our crop plants. Somatic hybrids can, be identified by using several approaches., Cellulose + pectinase, Plant cell, Protoplast, (plant cell, lacking cell wall), Parent A protoplast, , Nucellus culture, l, , Parent B protoplast, , polyethylene, glycol (PEG), cell fusion, nuclear fusion, somatic hybrid cell, , Embryo culture, l, Excision of young / fragile / dormant embryos from, developing seeds and their cultivation on a nutrient, , medium is called embryo culture. Embryo culture, has many applications., The plantlets obtained from this culture can be, removed from culture vessels and established in, the field. During hardening process plantlets are, kept under reduced light and high humidity for a, suitable period of time. It makes the plantlets, capable of tolerating the relatively harsher, environments outside the culture vessels., Embryo culture is used in –, –, Embryo Rescue : It is taking out the fragile, embryos from fertilised ovules of interspecific, crosses before their abortion (due to, nonfunctioning of endosperm and other, postfertilisation barriers) and culturing them, to form viable hybrid seedlings, e.g., Jute, (Corchorus oliorius X C. capsularis), Tomato, (Lycopersicon, peruvianum, X, L., lycopersicum), Bean (Phaseolus vulgaris X, P. angustissimus), Rice (Oryza sativa X O., officianalis)., –, Orchids : Orchid seeds lack stored food., Embryo culture helps in developing seedlings, from all the seeds. The technique is also used, in clonal multiplication., –, Dormant seeds : Inhibitors present in, endosperm and other parts of seeds do not, allow the embryos to grow. Embryos of such, seeds can be excised and grown over culture, medium to form seedlings. It eliminates the, action of inhibitors and dormancy., –, Rare plants : The technique is useful in, multiplication of some rare plants, e.g.,, Makapuno nut., , l, l, , Strictly parental type plants can be obtained, through nucellus culture, which is completely free, of microorganisms including viruses. Such plants, obtained through nucellus culture maintain their, characters for a long time., In plant biotechnology, most useful product is a, plantlet that have been genetically altered., There are many uses of genetically altered plantlets., These are as follows –, –, Rapid clonal propagation : A clone is a group, of individuals or cells derived from a single, parent individual. All plantlets regenerated, from a callus or suspension culture have same
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 603, , ▓ńďňŚ– ♀ĽřřśĚ– ►śńŚśŕĚ, , –, –, , genotype and constitute a clone. These, plantlets can be used for rapid clonal, propagation of superior lines., Somaclonal variation : It is genetic variation, present among plant cells of a culture. It has, been used to develop several useful varieties., Transgenic plants : A gene that is transferred, into an organism by genetic engineering is, called transgene. An organism that contains, and expresses a transgene is known as, transgenic organisms. The cells containing and, expressing transgenes can be easily selected in, vitro. Ultimately, plantlets can be regenerated, from these cells. These plantlets give rise to, the highly valuable transgenic plants., , l, , l, , Application of plant tissue culture, Some important applications of plant tissue culture, are – micropropagation, production of disease free, seeds, androgenic haploids, somatic hybridization,, cryopreservation etc., Micropropagation – Micropropagation or cloning, , l, , l, , l, , is applied to a technique devised to produce strong, and healthy plantlets by vegetative multiplication, in large quantity. It has been successfully used for, commercial production of potato, bananas,, cardamoms, orchids, gerberas etc., Production of disease freeplants – The multiple, shootlet production technique is used to get, disease – free healthy plants such as cassava, potato,, sugarcane, strawberry, dahlia, sweet potato etc.., Androgenic haploids and uses – Haploid plants, are very useful because they possess only one set, of chromosomes. The advantage of haploids in crop, improvement are that they are useful for induction, of mutations, when haploids are treated with, colchicine, they produce homozygous diploids,, during hybridization, haploids combine the, advantage of recombination, segregation etc., Protoplast, technology, and, somatic, hybridization – The naked protoplast of two, different plants fuses together to form a hybrid., This is known as somatic hybridization. Somatic, , Table : Important applications of microorganisms, animal cells and plant cells in agriculture, industry and, human health, S.N., , Organism/cell, , Applications, Agriculture Industry and Human health, Nontransgenic strains/lines, , 1., , Microorganisms, , Biofertilizer, Biopesticide, , Vaccine production, antibiotic, production, vitamins, organic, compounds, single cell protein, , 2., , Animal cells, , –, , Vaccine production, animal proteins, (including antibodies), , 3., , Plant cells, tissues and organs, , Micropropagation, plants, Somatic, Somaclonal variants, , Haploid Secondary metabolites including, hybrids pharmaceutical compounds,, micropropagation, , Transgenic strains/lines, 4., , Microorganisms, , –, , Noval pharmaceutical proteins, vaccines, new products, , 5., , Animals cells, , –, , New pharmaceutical proteins,, vaccines, antibodies, , 6., , Plant cells, , Transgenic crops with resistance New pharmaceutical proteins, New, to herbicides, insects, viruses; high value products, genetically, modified quality; improved modified food, nutrition
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 604, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , hybridization has been successfully used in many, crops. Pomato in an example of somatic, hybridization between tomato and potato., In vitro plant germplasm conservation &, cryopreservation – Storage of plant germplasm, can be done by storing their seeds and their, propagules. Seeds and their vegetative materials, are stored and maintained in gene bank. It provides, valuable materials to plant breeders., Artificial seeds – Artificial seeds of those plants, which either do not produces seeds or produces, seeds in very less quantity, are produced through, biotechnology. Artificial seeds are produced by, cellular totipotency and somatic embryogenesis., Biotechnology is involved in the preparation of, useful products (like foods, dairy products,, alcohol beverages, biogas, biofertilisers, organic, acids, enzymes, vitamins, antibiotics, vaccines,, hormones monoclonal antibodies) and used in, sewage treatment, tissue culture, genetic, engineering by using microbes., , GENETICALLY MODIFIED CROPS, (GM CROPS), l, , l, , l, , l, , l, , Genetically modified or GM crops contain and, express one or more useful foreign genes or, transgenes., Genetically modified crop or transgenic crop are, prepared by transferring genes from one plant to, other. The plant in which foreign genes are, introduced are known as transgenic crops., There are two ways to introduce foreign genes in, plant cells –, –, Through vector, –, Through direct introduction of DNA involves, cocultivation,, electroporation, and, microinjection., This technology is superior to breeding, programmes because in breeding only the already, present genes are reshuffled and that changes would, occur in all traits for which the parents are different., A transgene can perform four functions –, –, Mask expression of a native genes. In ‘Flavr, Savr’ variety of Tomato, expression of gene, for production of polygalacturonase was, blocked. Enzyme polygalacturonase degrades, pectin. In the absence of enzyme, pectin, degradation is stopped and the fruit remains, , l, , l, , l, , fresh for long. It retains flavour, has superior, taste and higher quantity of total soluble solids., –, Modify an existing biosynthetic pathway :, Transgenic Golden Rice and transgenic, Potato produce respectively higher content, of vitamin A and protein., –, Produce a protein of interest : The protein, hirudin present in leech prevents blood, clotting. Its gene was chemically synthesised, and introduced in Brassica napus. The seeds, of the latter came to have hirudin which could, be extracted and purified., –, Produce a phenotype : Soil bacterium, Bacillus thuringiensis possesses a gene cry, which produces a number of crystal or Cry, proteins. Each type of Cry protein is toxic to, certain group of insect larvae. cry gene of, Bacillus thuringiensis has been successfully, transferred to a cotton variety called Bt cotton., It is not attacked by bollworm and other, insects. The variety is being sown in India, and several other places. Other GM crops are, being cultivated in USA, Europe and many, more countries. However, caution is required, in developing GM crops without proper, safeguards because (i) Pollen of transgenic, crops may carry the transgenes to wild, relatives. (ii) Gene transfer from GM crops to, weeds would make them more virulent. (iii), Transgenic crops may become persistent, weeds. (iv) Transgenic crops would disturb, the balance of nature and damage the, ecosystem., In India, it has been argued that transgenic crops, may be harmful to the environment. The transgene, may be transferred through pollen from these crops, to their wild relatives. In many cases, such a gene, transfer may make the weeds more persistent and, damaging. In view of this, transgenic crops should, not be grown in those areas where their wild, relatives occur in the fields or the surrounding areas., The food prepared from the product of genetically, modified (=transgenic) crops is called genetically, modified food or GM food., GM food differs from the food prepared from, the product of conventionally developed varieties, because it contains the protein produced by, transgene, enzyme produced by antibiotic resistant
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ♀ĽřřśĚ– ►śńŚśŕĚ, , l, , gene that was used during gene transfer by genetic, engineering and contains the antibiotic resistant, gene itself., GM food could lead to the some problems when, they are consumed such as it may cause toxicity or, produce allergies, bacteria present in the alimentary, canal of the human could take up the antibiotic, resistant gene and become resistant to the concerned, antibiotic. As a result, these bacteria could become, difficult to manage., , SUSTAINABLE AGRICULTURE, l, , l, , l, , l, , l, , l, , Sustainable agriculture is the practice of, management and successful use of bioresources in, agriculture to meet the present demand without, compromising the ability of future generations to, meet their own needs., Sustainable agriculture should use renewable, resources, should not cause pollution and should, maintain optimum yields., Biotechnology contributes to sustainable agriculture, by developing biofertilisers, biopesticides,, disease – and insect resistant varieties and single, cell proteins., Biofertilisers are microorganisms that make, available to plants either atmospheric oxygen or soil, phosphorus. There are several microorganisms such, as bacteria, cyanobacteria that can fix atmospheric, nitrogen and make them available to plants. Some, of these are Rhizobium, Anabaena and mycorrhiza., Biopesticides consists of viruses, bacteria,, protozoa, fungi or mites that help control diseases,, insects or weeds. Biological control of pests, (organisms that damages plant or plant product), involves bioherbicide and bioinsecticides., Bioherbicides utilizes insects which would feed, selectively on a weed, e.g., a cochineal insects,, feed upon Opuntia., , l, , l, , l, , l, , l, , l, , l, l, , 605, , Bioinsecticides includes pathogen, parasites and, predators. A large number of harmful insect pest, are controlled by other insects, pathogens, parasites, or predator, e.g., frogs, birds etc. eat insect pests., Integrated pest management involves various, types of controls to ensure continued production, from soil without excessive use of synthetic, pesticides. IPM suggest different physical, chemical, and biological methods integrated to provide better, protection., Genetic engineering has enabled the development, of crop varieties resistant to certain insects and, diseases. Plant diseases are caused by viruses,, bacteria, fungi and nematodes. The most successful, approach for the production of virusresistant, plants is the transfer of virus coat protein gene, into the plants., Incorporation of Bt/cry gene in cotton has made, it largely resistance to bollworm and other insects., Similar resistance is being developed in other, plants., Development of disease and insect resistant varieties, would minimise the use of pesticides, prevent, pollution and enhance agricultural production., Single cell protein (SCP) is production of microbial, biomass for consumption as human food or animal, feed by growing algae, fungi, yeasts and bacteria, over agricultural wastes (e.g., sawdust, paddy straw,, paddy husk) and organic wastes of industry., Commercially SCP is being produced by yeasts, and Fusarium graminearum., SCP provides a valuable protein rich supplement, in human diet. It also reduce the pressure on, agricultural production systems for the supply of, required proteins. SCP production based on, industrial effluents helps reduce environmental, pollution.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 606, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 67, , Economic Botany, l, l, , l, , l, , l, , l, l, , Economic botany is broadly defined as the study, of the relationship between humans and plants., This interdisciplinary study encompasses the fields, of arthopology and botany as it explores the, countless ways humans employ plants for food,, medicine, textiles, shelter and more., Economic botanists explore the interface between, people and plants to describe the cultural uses of, plants, explain the origin of specific useful plants, and develop strategies of the sustainable use of, plant resources., Ethnobotany is the study of how people of a, particular culture and region make use of indigenous, plants., Ethnobotany has its roots in botany, the study of, plants. Botany, in turn, originated in part from an, interest in finding plants to help fight illness., Pharmacognosy is the study of medicinal and toxic, products from natural plant sources., As modern medicine and drug research advanced,, chemicallysynthesized drugs replaced plants as the, source of most medicinal agents in industrialized, countries., , FOOD PLANTS, l, , l, l, l, , l, l, l, l, , l, l, l, , l, , l, , Food plants can be classified as cereals, pulses,, nuts, vegetables, fruits, spices and beverages., , Cereals, l, , l, , The term cereals has been derived from the Roman, Goddess namely ‘ceres’. According to Romans, ‘ceres’ is giver of grains., The cereals are caryopsis fruits belonging to family, Poacea., Cereals are major (paddy, wheat, maize), minor, (rye, barley, oats), small grains and millets (jowar)., Rice (Oryza sativa) probably originated in Indo, china or India., , l, l, , l, l, l, , Rice is the principal cereal of tropics. A.P., Assam,, Bihar, M.P., Maharashtra, Tamilnadu and West, Bengal are the main rice growing states in India., Rice grains are used as first staple food in World, and India. It is also used as stock and poultry feed., These plants are 60 – 120 cm. tall herbs with, adventitious fibrous root system., The inflorescence is terminal and the spikelets are, arranged in panicles., Rice grains contain about 90% carbohydrate,, 8–10% proteins, 1% fats and about 1% mineral, matter., The grain with its brown lemma and palea is termed, as hull., The polished rice has low nutritive value as it, lacks proteins, vitamin and fat contents., Some of the common varieties of rice are Basmati, 307, IR24, IR48, Krishna, Jaya, Padma, Ratna,, Pankaj, Jamuna, Sabermati, ADT27 etc., New varieties of rice are being developed at Indian, Agricultural Research Institute, New Delhi, Rice, Research Institute, Cuttack and International Rice, Research Institute, Manila (Philippines)., Its flour is used in pastries, puddings, icecreams, etc. Rice bran oil is used in preparing soap and, cosmetics. Sake (beverage of Japan) is obtained by, fermenting rice., Wheat is the principal food in temperate countries, and the second staple food of our country., Wheat has multiple origin: soft wheat from south, west India and Afghanistan, Durum wheat from, Algeria and Greece and Einkorn from Asia minor., The plants are annual herbs whose grains contain, 69–70% carbohydrates., USA is the largest wheat producing country in, the world., The main wheat producing states in India are
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ĘŐňŐŇĽĘ– ▲ŐŚďňť, , l, l, , l, , l, , l, , l, l, l, l, , l, l, , l, , l, , l, l, , l, l, , Bihar, Madhya Pradesh, Maharashtra, Punjab,, Rajasthan and Uttar Pradesh., The grains are generally sown in the months of, October/November in our country (Rabi crop)., At least nine kinds of wheat has been identified, namely – Einkorn, Emmer, Spelt, Polish wheat,, Poulard wheat, Club wheat, Durum wheat,, Common wheat and Tinopheevi., The diploid wheat is the oldest and unfit for human, consumption. The tetraploids came into being due, to a probable crossing of diploid with the grass, Aegilops speltoides. The hexaploids are the most, recent., Some high yielding varieties of wheat include Kalyan, Sona (HD1593), Sonalika (HD1553), Pratap (HD, 1981) and disease resistant varieties like HD2135,, HD2189, Lerma Rojo, Sonara64, Arju, Hera, Janak,, WH147, KSML3, C306, UP115 etc., Norman Borlaug is called the father of green, revolution for his discovery of Sonara64, Lerma, rojo64 etc., The flour of wheat is used for various purposes., The straw is used as fodder., Corrugated paper is made from wheat straw., Maize (Zea mays) or ‘Indian corn’ is the gift of, America of cereals., In India, it is grown in Andhra Pradesh, Bihar,, JammuKashmir, Madhya Pradesh, Punjab and, Uttar Pradesh., Maize is grown as kharif crop in India., The important varieties of maize are – Ganga Safed2,, Ganga5, Him123, Decan 101, Vijay, Ganga9,, Histarch, Jowahar, VL54, Amber, Deccan etc., The plants are tall herbs measuring from 1 to 4.5, meters in height, with adventitious fibrous and, stilt root systems., The fruit is a caryopsis possessing two types of, endosperm, white and yellow, thus exhibiting, the phenomenon of Xenia., Maize grains are deficient in amino acid lysine,, tryptophan and rich in thymine., Beside pop corn, flakes, poultry grit and animal, feed, corn starch, industrial alcohol and syruph are, also made from maize grains., An artificial fibre is also prepared from the maize, protein, Zein., Barley (Hordeum vulgare) was first domesticated, cereal., , l, l, l, l, l, l, , l, , l, , 607, , It is sown as rabi crop and used in making malt,, whisky, and other alcoholic beverages., Its flour is used for making chapatis., Oat (Avena sativa) is most nutritious among cereals, as it contains high proteins, fats and minerals., United States leads the world in production of oats., Oats are thought to be having multiple origin., Oat meal is used mainly in cakes biscuits, etc. It, is not good for preparing breads because glutein, content is absent in grains., Rye (Secale cereals) is of more recent origin as, compared to other cereals. It is probably a native, of Black and Caspian Seas region of Central, Eurasia., It is mainly used in preparing bread as the grain, contains glutein., Triticale (Triticosecale) is the first man made, cereal or crop produced by intergeneric, hybridization between wheat (Triticum sps.) and, European rye (Secale cereale), i.e.,, Triticum × Secale cereale ®, Triticosecale or Triticale., It is like wheat but grains are shrievelled., , l, l, , l, , l, , l, l, , Small sized grains are called millets whose edible, portion is endosperm., The important millets are – Jowar (Shorghum, vulgare), bajra (Pennisetum typhoides), Ragi, (Eleusine corana), common millet (Panicum, miliacium), foxtail millet (Setaria italica) etc., Sometimes seeds of other plants are used like cereals, and millets as source of food, although they are not, grasses, these seeds are known as pseudocereals., There are two widely used pseudocereals –, –, Buck wheat : Fagopyrum sagittatum or F., esculentum (Kuttu)., –, Gorgannut : Euryale ferox (Makhana)., The seeds of buck wheat are grinded and flour is, used for porridge, pancakes, etc., Buck wheat is a source of a glucoside, rutin which, is used in the treatment of hypertension and high, blood pressure., , Pulses, l, , l, , Pulses are next to cereals as source of human food., They belong to family Leguminosae which has a, characteristic fruit called a legume or pod., Type of foods present in the pulses are proteins,, carbohydrates and oils.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 608, , l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Proteins occur as aleurone grains. This high protein, content is due to the presence of root nodules in, legumes., Pulses store food materials in their cotyledons,, seeds of pulses are nonendospermic., Cultivation of pulse crops increases the fertility, of land since Rhizobium are present in their root, nodules which fixes atmospheric nitrogen for plant., Pulse crops are useful for crop rotation and in, mixed cropping., Some of the important pulses are : gram (Chick, Pea) – Cicer arietinum, Red Gram (Pigeon Pea,, Arhar, Tur) – Cajanus cajan, Black Gram (Urd) –, Vigna or Phaseolus mungo, Green Gram (Mung) –, Vigna radiatus = Phaseolus aureus, Pea (Mattar), – Pisum sativum, Soyabean – Glycine max, Mat, Bean (Moth) – Vigna aconitifolia = Phaseolus, aconitifolius, Lentil (Masur), Lens culinaris, (L. esculenta), Red kidney bean (Rajmah) –, Phaseolus vulgaris, Lablab – Lablab purpureus, (Dolichos lablab), Guar/cluster bean – Cyamopsis, tetragonoloba, Cow Pea/Lobia – Vigna unguiculata, (V. sinensis), Phaseolus lunatus., Soyabean contains 40% proteins, lower cholesterol, and LDL. An anticancer ingredient called genistein, is also present. Also yields oil. Soyabean milk is, a refreshing drink., Lathyrism, a crippling disability marked by, muscular weakness, tremors and paraplegia is, caused by eating seeds of Lathyrus sativus (Grass, Pea, Chickling Vetch, vern, Khesari Dal). The seeds, contain osteotoxin bamino propionitrile (BAPN), and water soluble neurotoxin bNoxalyl amino, alanine (BOAA). Red Kidney Bean and French, Bean possess lectins which are destroyed only on, boiling for some time. Low temperature cooking, or eating raw soaked beans can be dangerous., , l, l, , l, l, , Urease enzyme is obtained from arhar which is, used in estimation of urea in urine and blood., Ardil protein is obtained from ground nut (=Arachis, hypogea, pea nut) which is used in manufacturing, fibres., Tree legume is Prosopis juliflora., Rotenone is a white crystalline substance obtained, from dry roots of Derris and Lonchocarpus. It is, used in fish poisoning and as insecticide., , Nuts, l, l, , l, , l, , l, , l, , l, , Literally a nut is defined as a simple, dry,, indehiscent fruit having a hard pericarp., The nuts have high protein contents (Prunus,, Pistacia), high oil content (Cocos, Anacardium,, Juglans), and high carbohydrate content, (Castanea, Quercus)., The cashew nut (Anacardium) is a native of Brazil., It’s seeds contain 47% fats, 22% carbohydrates and, 21% proteins. They are eaten raw or roasted., Besides, a beverage is also prepared from it., The almond (Prunus amygdalus) is a native at, Mediterranean region. The trees produce drupes, and the seeds may be sweet or bitter., The pistachio nut (Pistacia vera) originated in West, Asia. The drupes contain green seeds which are, eaten raw or roasted or salted., The English walnut (Juglans regia) are trees, producing drupes with edible cotyledons and the, plant produces useful timber., The coconut (Cocos nucifera) is a native of Malaya., The plants are trees showing palm habit. It is, perhaps the economically most useful plant. All, parts are used, as kernels are edible, endosperm, edible, copra yields oil, mesocarp provides coir,, dry leaves used for thatching., , Vegetables, l, , l, l, , l, , l, , l, , The vegetables store food material in different parts., They may be classified as earth vegetable, herbage, (leafy) vegetables and fruit vegetables., The earth (underground) vegetable may store, food material in their root, stem or leaves., Among the most common edible roots are Beta, vulgaris (beet), Brassica rapa (turnip), Daucas, carota (carrot), Ipomoea batata (sweet potato) and, Raphanus sativus (radish), Manihot esculenta, (Tapioca), Dioscorea alata (yams)., The underground stem vegetables include, Solanum tuberosum (potato), Colocasia esculenta, (Arvi), Helianthus tuberosus (Hathichuk) etc., The underground leaves include Allium cepa, (onion) and A. sativum (garlic)., Onion is a tunicated bulb and store reserve food, in its scaly leaves. It has a pungent taste which is, due to presence of an acrid oil, allyl sulphide., The herbage vegetables include Brassica oleracea, var. botrytis (Cauliflower), B. oleraceae var.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 610, , ŕďőĽę– ĐĽŐńŐĹť, , Table : Some common edible fruits, , 1., , Common, Name, Apple, , 2., , Mango, , Pome of false, fruit, Mangifera indica Fleshy drupe, , 3., , Lemon, , Citrus limon, , Hesperidium, , 4., , Orange, , Citrus reticulata, , Hesperidium, , 5., , Grapes, , Vitis vinifera, , Berries, , 6., , Banana, , Musa paradisiaca Berries, , 7., 8., , Litchi, Pineapple, , Litchi chinensis, Ananas comosus, , 9., 10., 11., 12., , Pomegranate, Mulberry, Guava, Papaya, , Punica granatum, Morus alba, Psidium guajava, Carica papaya, , 13., , Custard, apple or, Sugar, apple, Fig, Bel, , Annona squamosa –, , –, , –, –, –, Papain enzyme is obtained from, papaya used for digesting protein, –, , Ficus carica, Aegle marmelos, , –, –, , –, –, , 14., 15., , Botanical name, , Type of fruit, , Pyrus malus, , l, , Plants which are used for obtaining industrial raw, materials are called industrial plants., Common industrial material obtained from plants, are wood, latex, oils, gums, dyes, sugar and paper, etc., , l, , l, l, , Wood, l, , l, , l, , –, , Mesocarp, , Rich source of vitamin A, C and, K, Source of vitamin C, , Juicy placental, hairs, Juicy placental, hairs, Pericarp and, placenta, Pulp (mesocarp, and endocarp), , Syconus, Balausta, , Forest besides regulating the climate, temperature, and checking erosion, produces wood and, industrial materials., The wood is superior to any metal in it’s, availability, cheapness, toughness, strength and, elasticity., The secondary xylem mainly constitutes the ‘wood’., , l, l, l, l, , Uses, , Thalamus, , One seeded nut Fleshy aril, Sorosis, Mesocarp and, endocarp (juice), Balausta, Succulent testa, Sorosis, Perianth, –, –, –, –, , INDUSTRIAL PLANTS, l, , Edible part, , Source of vitamin C, –, High content of carbohydrates,, fats proteins. Plantain is cooked,, or make into flour, –, –, , The secondary xylem formed in spring forms the, spring wood or early wood and the one formed, in autumn forms the autumn wood or late wood., The spring wood is light coloured whereas, the, autumn wood is dark coloured., The wood is made up of tracheids, vessels, fibers, and parenchyma. It is also identified on the basis, of ray characteristics, it’s grain, figure and texture., Due to absence of vessels in gymnosperms its wood, is called nonporous wood., The structural arrangement of various wood, components is called as grain of wood., The relative size and quality of various wood, elements is termed as texture of wood., The design or pattern that appears on the surface
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◄ĘŐňŐŇĽĘ– ▲ŐŚďňť, , l, , l, , l, , l, , l, , of wood is referred to as figure of wood., The properties possessed by any wood are it’s, strength, stiffness, toughness, hardness and, cleavability. The lightest wood is that of Ochroma, lagopus (specific gravity 0.12) and heaviest south, American iron wood (Krugiodendron ferreum) and, Guaiacum officinals., The reaction wood is formed in response to a, physical stress. It is of two types : compression, wood and tension wood., Removal of moisture from the wood is called as, timber seasoning. It is done in two ways : air, seasoning and kiln seasoning., Some specific items are made from specific wood, such as –, – Cricket bat – Salix alba and its other, species., – Hockey sticks – Stick from Morus alba and, blade from Dalbergia sissoo., – Pencils, – Juniperus sp., – Gun stocks – Juglans regia., Some other wood obtained from various trees, are – Indian black wood (Dalbergia latifolia), ebony, wood (Diospyros ebenum), red wood (Sequoia, Sempervirous)., Table : Common wood plants, , Scientific name, Tectona grandis, (Sagoun), , Used for, Construction purposes, furni, ture, railway sleepers, carving, etc., Shorea robusta, Used for railway sleepers, doors,, (Sal), windows, beams, planks, bod, ies of carts and boat building., Dalbergia sissoo (Shisam) Used for making musical instru, ments, shuttles, sports goods,, shoe heels, hookah tubes and, tobacco pipes. The timber is also, used for furniture, cabinet and, carriages., Pinus roxburghii, Used in packing boxes, match, (Pine), boxes, household goods, con, struction works and cheap, furnitures., Cedrus deodara, Used for house building, rail, (Deodar), way sleepers, ports, floor, boards, window frames and light, furnitures., , Sugar, l, , The main source of sugar is Saccharum, officinarum. Beside this Beta vulgaris (sugarbeet), , l, l, , l, , l, , l, , l, l, , l, , 611, , and palm are also the source of sugar., Sugarcane stem contains about 80% juice., Glucose is the first sugar manufactured by a green, plant. Commercially the glucose or grape sugar, is prepared from starch., Fructose is also called as fruit sugar. It is present, in many fruits along with glucose. Commercially,, it is prepared from inulin, a polysaccharide present, in the roots of Dahlia and Helianthus., Mannose does not occur freely in plants. However, it can be obtained from the juice of Fraxinus, ornus (Manna ash) by oxidation., Maltose does not exist freely in plants but can be, obtained from starch by the action of the enzyme, diastase., Molasses is the juice left after the crystallization, of sugar., From molasses, ethyl alcohol, rum, acetic acid and, glycerine are prepared. Bagasse (fibrous residue, left after the extraction of juice) is used in the, manufacture of paper and cardboard., Some other sugar yielding plants are Phoenix, sylvestris, Borassus flabellifer, Caryota urens., , Paper, l, l, l, l, l, l, , Egyptians made paper from Cyperus papyrus and, from this, the name is derived., Paper is a felted or matted sheet of cellulose (or, synthetic) fibres., The raw materials for paper manufacture are, contributed by wood fibers, cotton and linen etc., Wood pulp is generally obtained from Picea, Abies, Betula lutea etc., Fine grade paper is prepared from cotton and linen, fibres., Pulp of bamboo (Bambusa arundinacea) is used, for the manufacture of printing paper., , Dyes, l, l, , l, l, , Different parts of many plants produce dyes which, are chiefly used in textile industry., Dyes come from the roots of Berberis, Moringa,, Rubia and rhizomes of Curcuma. They are also, produced in the bark of Quercus, Tectona etc. and, also in the leaves of Indigofera and Lawsonia., The flowers of Butea, Carthamus, Crocus,, Nyctanthes, Toona and Wrightia produce dyes., Dyes are also obtained from the fruits of Mallotus, and Rhamnus, seeds of Bixa and Wrightia and gum, resin of Garcinia.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 612, , ŕďőĽę– ĐĽŐńŐĹť, , Fibres, l, l, l, l, l, , l, , l, l, l, l, , l, , Fibres fulfill the second most necessary, requirement of human beings i.e., clothings., Botanically fibres are the sclerenchymatous cells, occurring in different parts of the plants., They are made up of cellulose or hemicellulose, with deposition of lignin., The longest fibre of Boehmeria nivea measures, 55 cms in length., Some other fibre yielding plants are Hibiscus cannabinus, (bimbli juli), Boehmerea nivea (remie), Cannabis, sativa (hemp), Agave sisalana (sesal hemp) etc., Largest, toughest, strongest and most durable, fibres are obtained from secondary phloem, used, for ropes, brushes, carpets etc., Textile fibres are categorised in three categories, surface fibers, soft fibers and hard fibers., Surface fibres are short fibers occurring on surface, eg. cotton., Soft fibres are the bast fibers belonging to pericycle, and phloem, e.g. jute, flax, hemp etc., Hard fibres are found particularly in the leaves of, monocots, e.g. coir., , l, , l, , Brush fibres are obtained from the leaves of, Borassus, Caryota, inflorescence of Sorghum, etc., Planting and rough weaving fibers are used for, making hats, mats, baskets etc. In all these cases, fibres from palms and grasses are used., The filling fibres comes from Bombax, Calotropis, and Typha., , Oils, l, l, l, l, , l, , The oils are generally classified as essential or, volatile oils and fatty or fixed oils., The essential oils are extracted by distillation or, expression or by solvents., They are either used in perfumery or in other, industries., The essential oils used in perfumery are, contributed by many plants such as Cananga, odorata, Jasminum spp., Lavendula officinalis,, Rosa spp., Santalum album (chandan)., Several plants yield essential oils used in other, industries, e.g., Cinnamonum camphora (kapur),, Eucalyptus spp., Syzygium aromaticum (clove)., , Table : Fibre yielding plants, Comman, name, , Scientific name, , Fibre obtained, from, , Cotton, , Gossypium sp., , Epidermal hair, of seed, , Important varieties of cotton are : Virnar, Jarlia, Daulet,, Jayawant, Vijay, Digvijay, etc. Cotton is very useful raw, material for various industries, i.e., plastic, rayon and, explosives fibres are present in the stalk of the plant which, are used for paper making. Cotton seed oil is obtained, from kernels which is one of the most important fatty, oils., , Jute, , Corchorous, capsularis, , Bast fibers, obtained from, secondary, phloem of stem, , These fibres are used in making carpets, curtains, twines,, ropes, etc. Jute fibres deteriorate rapidly when exposed, to moisture., , Sunhemp, , Crotolaria, junceae, , These are used in making coarse cloth, ropes and twine,, etc., , Flax, , Linum, usitatissimum, , Bast fibers, present in, phloem region, just outside, cambium, Fibres occurring, in pericycle, , Coir, , Cocos nucifera, , Mesocarp, , Uses, , Flax fibres are moisture or water resistant so used in, making fishing nets, ropes. These fibres become more, strong when wet than dry., Highly resistant to water.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 613, , ◄ĘŐňŐŇĽĘ– ▲ŐŚďňť–, l, , l, , l, , l, , l, l, , The fatty oils are categorised as drying oils, semi, drying oils, nondrying oils, vegetable fats and, waxes., The drying oils dry up forming an elastic film., They are contributed by plants like Glycine max,, Juglans regia and Linum usitatissimum. Besides,, species of Cannabis, Papaver and Perilla also, provide drying oils., The semi drying oils are contributed by plants like, Brassica spp., Gossypium spp., Helianthus annuus,, Sesamum indicum, Zea mays., The non drying oils are contributed by Arachis, hypogea, Olea europea, Ricinus communis and also, by Camellia sansaqua and Moringa oleifera., The vegetable fats come from Cocos nucifera,, Elaeis guinensis (palm), Madhuca indica (mahua)., The waxes are produced by plants like Calathea, lutea, Ceroxylon andicola, Euphorbia, antisyphilitica, Myrcia and Simmondsia sinensis, (jojoba)., , Rubber, l, , Rubber is obtained from the latex of various, woody plants, especially from Hevea brasiliensis, belonging to family Euphorbiaceae., , l, , l, , l, l, l, l, l, , The latex is present in laticiferous cells and vessels, distributed in the bark, leaves and other tender parts, of the tree., The latex is a milky white emulsion in water, containing acids, salts, sugar, oils, resins, gums,, proteins and hydrocarbons., Latex is tapped by making a sharp incision in the, bark. Collected latex is processed to get rubber., Vulcanization is done by heating rubber with, sulphur., Indian rubber (Ficus elastica) family moraceae is, found in Assam and Khasia hills., Rubber is also obtained from species of Castilla,, Ficus, Manihot, Parthenium and Taraxacum., Other latex products are gutta percha from, Palaquim gutta, chicle from Achras sapota (for, making chewing gum) and balata from Malinkara, bidentata., , Tannins, resins and gums, l, , l, , Tannins are complex organic substances,, chiefly glucosidal in nature and medicinally, astringents. They are used for tanning hides and, making inks., Tannins is obtained from various parts of plants, , Table : Essential oil and their uses, Type of oil, , Scientific name, Vetiveria zizanioides, , Uses, , It is obtained from roots and rhizomes and is used for preparing and, flavouring fruit juices, icecreams, etc., It is obtained by distillation of oleoresin which is an exudate coming, Pinus longifolia, Terpentine oil, out after wounding the tree., Jasminum auriculatum This oil is obtained from flowers of the plant used in hair oils and, Jasmine oil, perfumes., The oil is used in perfumes, soaps and in medicines., Sandal wood oil Santalum album, Lavendula officinalis The fresh flowering tops of the plants are used for obtaining oil. It, Lavender oil, is a constituent of Eau de Cologne and other high grade perfumes., This oil is obtained from the peels of fruit and used in confectionery,, Citrus reticulata, Mandarin oil, soaps, etc., Lemongrass oil Cymbopogon citratus The leaves on distillation give a reddishyellow oil with high citral, content (7080%), which is used in perfumes, cosmetics, toilet soaps,, bath salts, etc., This oil is obtained by distillation of leaves of this grass, which is, Cymbopogan nardus, Citronella oil, used in cheap soaps, perfumes and also as an insect repellant., This oil is obtained by distillation of heart wood of this eastern red, Cedar wood oil Juniperus virginiana, cedar. It is used as clearing agent in preparation of permanent, microscopic mounts, in perfumes, soaps, deodorants and also used, in fly sprays and as moth repellant., Khus oil
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 614, , l, l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , like roots (eg. Rumex, Polygonun), bark (eg., Acacia, Casuaria, Zizyphus), leaves (eg. Rhus),, fruits (Terminalia, Quercus)., These are basis of blue black inks., Gums are complex carbohydrates which are widely, distributed in the plants. They are found as, cementing substances in the cell walls or produced, by cellulose decomposition., Commercial gum is obtained from the stems of, Acacia senegal (gumarabic), Sterculia urens, (Kuteera gum), Butea monosperma, Boswellia, Serrata, Achras Sapota (chewing gum) plants., The exudates of gum are collected after making, incisions in the bark. It exudes drop by drop as, viscous liquid and finally hardens., Different gums are used differently but in general, they are used as adhesive, in printing, polishes,, syruphs, cosmetics, as sizing material in cotton, and paper industries and in medicines., Resins are oxidation products of essential oils., Present in the specific canals resins are obtained by, , l, l, l, l, l, l, , tapping., Resins possess antiseptic qualities and hence, prevent the plant from decay., Being insoluble in water and soluble in organic, solvent resins are used in paints and varnishes., Resins are classified as hard resins, oleoresins, and gumresins., The common hard resins are damars, copals,, ambers, shellacs, lacquers, and mastics., The oleoresins include turpentines, balsams etc., The common gumresins are asafoetida,, galbanums, ammoniacum etc., , MEDICINAL PLANTS, l, , l, , Some plants have medicinal value due to the, presence of some chemical substances in their, parts which have a definite physiological effect, on body., Depending upon the plant organ from which the, drug is obtained, the drug plants are divided into, following categories given in the table., , Table : Medicinal plants, Uses, , Name of Drug/plant Scientific name, Aconite, , Aconitum napellus, , For cholera and leprosy., , Belladona, , Atropa belladona, , Atropine alkaloid is obtained from it which is used for dilating, pupil of eye (i.e., in eye testing)., , Liquorice, , Glycyrrhiza glabra, , The roots contain glycyrrhizic acid. It is expectorant, laxative, given in bronchitis and chest complaints., , Serpentine, , Rauwolfia serpentina, , About 30 alkaloids are extracted from root of this plant. Out, of which ‘reserpine’ is the most important one having sedative, influence and is used in lowering the blood pressure., , Ashwagandha, , Withania sominifera, , It is effective in treatment of rheumatic pain, inflammation, of joints, ulcers and to promote healing processes., , Asafoetida, , Ferula asafoetida, , This is oleoresin gum exuding from the roots. It is carminative,, digestive and antispasmodic., , Holy basil, , Ocimum sanctum, , The leaf juice is given in cold, cough and chronic fever and, is used to check vomiting., , Vasaka, , Adhatoda vasica, , The alkaloid vaccine is present in the leaves which is expectorant, and antispasmodic., , Saffron, , Crocus sativus, , The dried stigmas and tops of the style are medicinally used., , Santonin, , Artemisia cina, , A valuable drug santonin is present in the dried unopened, flower heads of the plant. This drug is one of the best remedies, of intestinal worms (wormicide)., , Violet, , Viola odorata, , The flowers are used for the treatment of coughs., contd...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 616, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 68, , Plant Pathology, l, , l, , l, , l, , l, l, l, l, l, l, , l, , l, , l, l, , Any distortion from the healthy structure and, normal physiological activities of the plant body, is called plant diseases., Such type of structural and physiological, abnormalities are harmful to the plant or its parts, or products and thus, reduce its economic value., A simple dictionary meaning of disease is any, departure from health, presenting marked, symptoms, malady, illness and disorder., The branch of botany or biological science that, deals with the study of nature, causes,, development, resulting losses and control of, plant diseases is known as plant pathology or, phytopathology (Phyton = plant, pathos =, suffering, logos = knowledge)., The causal agent of a disease is called pathogen., The plant harbouring the pathogen is called host., The chain of events that lead to the development, of disease in the host is pathogenesis., The establishment of a pathogen within the host, after its entry or penetration is called infection., The potential ability of a pathogen to cause, infection is called its pathogenicity., Theophrastus recorded his observations on, plant diseases, such as rust of wheat and barley, etc. in his book "Enquiry into plants"., Kuhn (1856) published the first book on plant, pathology entitled ‘Die Krankheiten der Kultur, Zewachge’., Famous plant pathologists are Butler, De bary,, Micheli, K.C. Mehta, Mundukar, Tirumalachar, Rangaswamy., Micheli (16791737) was the first scientist to, study fungi and their spores., Bacteria and fungi are pathogens postulated by, Robert Koch., , l, l, l, l, , l, l, , l, l, , l, l, l, l, , K.R. Kirtiker was the first Indian scientist who, collected and identified fungi., Germ theory of disease was proposed by Pasteur., Wheeler (1969) classified plant diseases on the, basis of symptoms., The science of plant pathology deals with four, major objectives. These are –, –, Etiology To study the living (animate) or, nonliving and environmental (inanimate), causes of plant diseases (i.e., the study of, pathogen)., –, Pathogenesis To study the mechanisms of, diseases development by pathogen (host, pathogen interaction)., –, Epidemiology To study the spread of, disease and modes of their transmission., –, Control To develop the suitable methods, of controlling the diseases and reducing the, losses caused by them., Pathogens are divided into three groups –, inanimate, viral and animate., Inanimate agents are abiotic, nonparasitic and, noninfectious agents, e.g. chemicals, pollution, etc., Viruses are intermediate between animate and, inanimate types, e.g. TMV, CMV. etc., Animate are biotic agents that remain in intimate, association with their host plants, e.g. bacteria,, fungi, algae, nematodes etc., Incubation is the interval between infection and, appearance of disease., Susceptible plants are those which are easily, attacked by some pathogen., Resistant plant are those which resists against, the effect of pathogenic activity., Inoculum is the source of infection or the organism, which initiates infection.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ▓ďŚĺŐńŐĹť, , TYPES OF PLANT DISEASES, l, , l, , l, , l, , On the basis of causes, plant diseases are –, –, Noninfectious diseases : The diseases, which are not related to animate or viral, pathogen are noninfectious and cannot be, transmitted from one diseased plant to, another associated with these diseases, they, are also known as nonparasitic diseases., –, Infectious diseases : These are caused by, parasitic organisms or viral pathogens under, a set of suitable environments. These, diseases are always infectious, sometimes, contagious (disease spread through, pathogen very rapidly) and are transmitted, from diseased to healthy plants in the field., On the basis of their occurrence diseases may be –, –, Endemic disease : A disease prevalent in and, confined to a specific area (district or country), and occurs more or less constantly year after, year, it is called endemic to that area., –, Epidemic or epiphytotic disease : The, epidemic or epiphytotic disease is one which, occur severely and widely among a large, section of population, but its occurrence is, periodic., –, Sporadic diseases : The disease occurs at, very irregular intervals and is not confined, to a particular area., A disease is said to be –, –, Localized, when it affects only and special, organs or parts of the plant., –, Systemic, when the effect is spread to entire, plant., On the basis of the nature of the causal agent,, the plant diseases may be grouped into following, categories –, –, Nonparasitic diseases : The diseases, caused by nonparasitic or abiotic agents, are known as nonparasitic diseases. Many, of the nonparasitic diseases cause heavy, loss but cannot be readily controlled because, they occur due to the improper environmental, conditions that are beyond man’s reach as, – low temperature, high temperature,, unfavourable, oxygen, relations,, unfavourable soil moisture relations,, accumulation of injurious impurities,, lightening injury, mineral deficiencies,, mineral excesses, injurious atmospheric, , l, , l, , 617, , gases, etc. Such diseases are not caused by, animate agencies or viruses. Therefore, they, remain noninfectious and are not, transmitted from one plant to other plants., –, Parasitic diseases : The diseases caused, by fungi, slime moulds, bacteria, algae,, parasitic, flowering plants, nematodes,, protozoa, birds, rodents etc. are known as, parasitic diseases., When the pathogen of a disease survives and, spread through soil, it is called soilborne, pathogen and such disease is called soilborne, disease., When the perpetuation and dispersal of disease, is through seed, they are known as seedborne, disease., , Common symptoms of plant diseases, l, , l, , l, l, , l, , l, l, l, l, l, l, l, l, , If entry of pathogens induces reactions in the, body of their hosts, resulting in the appearance, of certain abnormalities, such visible effects, induced in a host by the presence of the pathogen, are called symptoms., Symptoms may be divided into two groups on the, basis of whether the pathogen makes its external, appearance or causes internal disorders, resulting in symptoms., Death and discolouration of tissues/parts of, leaves, stems and roots is called necrosis., Pustules are small blister like elevations of, epidermis which are produced by pushing of, spores that are produced below., Excessive growth of tissue are of two types –, hypertrophy (increases in cell size) and, hyperplasia (increase in cell numbers)., In stunting growth is poor so that the size of the, plant and its leaves remain short., Pitting is the formation of series of depressions, on the surface of stem and fruits., Discolouration, softening and degeneration of a, succulent tissue is called rot., Mosaics are intermingled patches of green and, yellow colouration., Chlorosis is yellowing of otherwise green, structures such as leaves., Wilting is loss of turgidity and drooping of leaves, or shoots generally due to insufficiency of water., Excessive root branching occurs in nematode, infection., Galls are swelling or growth on all parts of plants.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 618, , l, l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , ‘Witches Broom’ is broom like growth of a, number of small narrow branches., Damping off is falling off of the seedling on the, ground due to destruction of tissues at the level, of soil surface., In leaf curls there is disturbance and curling of, leaves. Parts may also become thickened., Spots are dead tissues killed by parasites present, in leaves., In blight large number of leaves, blossoms and, twigs die., , l, l, l, , Types of pathogens, Fungi, l, There are over 10,000 fungal pathogens of plants., l, The fungal plant pathogens themselves fall into, two major groups, the biotrophs which feed from, living plant tissue and the necrotrophs which kill, plant cells and then live on the nutrients released., l, However, many plant pathogens adopt a hybrid, lifestyle, initially acting as biotrophs before, converting to a necrotrophic lifestyle. These are, called hemibiotrophs., l, The majority of phytopathogenic fungi belong, to the ascomycetes and the basidiomycetes., l, The fungi reproduce both sexually and asexually, via the production of spores., l, These spores may be spread long distances by, air or water, or they may be soil borne., l, Many soil borne spores, normally zoospores are, capable of living saprophytically, carrying out the, first part of their life cycle in the soil., l, Fungal diseases can be controlled through the, use of fungicides in agriculture, however new, races of fungi often evolve that are resistant to, various fungicides., Protozoa, l, There are a few examples of plant diseases caused, by protozoa., l, They are transmitted as zoospores which are very, durable, and may be able to survive in a resting, state in the soil for many years., l, They have also been shown to transmit plant viruses., l, When the motile zoospores come into contact, with a root hair they produce a plasmodium and, invade the roots., Bacteria, l, Most bacteria that are associated with plants are, actually saprophytic, and do no harm to the plant, itself., , l, l, , However, a small number, around 100 species, are, able to cause disease., Bacterial diseases are much more prevalent in sub, tropical and tropical regions of the world., Most plant pathogenic bacteria are rod shaped, (bacilli). In order to be able to colonise the plant, they have specific pathogenicity factors. There are, 4 main bacterial pathogenicity factors –, –, Cell wall degrading enzymes : used to break, down the plant cell wall in order to release the, nutrients inside. Used by pathogens such as, Erwinia to cause soft rot., –, Toxins : These can be nonhost specific, and, damage all plants, or host specific and only, cause damage on a host plant., –, Phytohormones : For example Agrobacterium, changes the level of auxin to cause tumors., –, Exopolysaccharides : These are produced, by bacteria and block xylem vessels, often, leading to the death of the plant., Bacteria control the production of pathogenicity, factors via quorum sensing., Mollicutes (bacteria that lack cell wall) are normally, transmitted by sapsucking insects, being transferred, into the plants phloem where it reproduces., , Viruses, l, There are many types of plant virus, and some are, even asymptomatic., l, Normally plant viruses only cause a loss of yield, and therefore it is not economically viable to try to, control them. The exception being when they infect, perennial species, such as fruit trees., l, Most plant viruses have small, single stranded, RNA genomes., l, These genomes may only encode 3 or 4 proteins:, a replicase, a coat protein, a movement protein, to allow cell to cell movement and sometimes a, protein that allows transmission by a vector., l, Plant viruses must be transmitted from plant to, plant by a vector., l, The vector is normally an insect, but some fungi,, nematodes and protozoa have been shown to be, viral vectors., Nematodes, l, Nematodes are small, multicelluar worm like, creatures., l, Many live freely in the soil, but there are some
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ▓ďŚĺŐńŐĹť, , l, , l, , species which parasitise plant roots. They are, mostly a problem in tropical and subtropical, regions of the world, where they may infect crops., Root knot nematodes have quite a large host, range, whereas cyst nematodes tend to only be, able to infect a few species., Nematodes are able to cause radical changes in, root cells in order to facilitate their lifestyle., , l, , l, , Dissemination of plant diseases, l, , l, , l, , Dissemination by wind : The spores of many, pathogens are disseminated by the wind., Sometimes, the diseased plant parts help, dissemination of diseases. Eg Rusts of cereals,, caused by Puccinia graminis, and late blight of, potato, incited by Phytophthora infestans, are, the common examples in which dissemination of, disease occurs by means of wind., Dissemination of water : The diseases like, wart, disease of potato, caused by Synchytrium, endobiotichum, and club root of crucifers, caused, by Plasmodiphora brassicae, are disseminated, from one field to another through irrigation or, flood water. Many of the bacterial diseases, e.g.,, citrus canker, caused by Xanthomonas citri, are, disseminated by splashing of rain drops., Dissemination by insects : Insects act as, important agents in the spread of plant diseases., A number of viral diseases are disseminated by, insects like leafhoppers, mealy bugs and aphids., Some insects are known to feed on diseased host, tissue thus carrying the inoculum. When such, insects visit the diseasefree plants, they cause, infection (Ergot of rye disease, caused by, Claviceps purpurea)., , Prevention and control of plant diseases, l, , l, l, , l, l, , The main object of plant diseases control is to, prevent the quantitative and qualitative loss of, crops due to the attack of pathogen and to, increase the economic value of the crop., The disease control follows two main principles, prevention and cure., Prevention is the protection of the host from, infection and exposure to the pathogen or from, environmental factors favourable to disease, development. This is called prophylaxis., Cure involves the destruction of the pathogen, after it has gained the entry of the host., Such methods are known as curative or, therapeutic measures., , l, l, , l, , l, , 619, , The various methods of prevention and control, of plant diseases are physical, chemical and, biological control methods., Physical control method involves the following, measures , –, Quarantine : Plant quarantine is the legal, restriction that aims at preventing the entry, of pathogens from infected to noninfected, areas., –, Eradication of alternate hosts : Many, diseases persist through alternative hosts, of the pathogen which provide shelter to, them under unfavourable conditions. Due, to removal of such host the pathogens are, not able to complete the life cycle., –, Certification and inspection : In various, countries, there are inspecting departments, which assure the entry of only certified seeds, or planting materials from abroad, or from, one part of the country to another., –, Crop rotation : When a particular crop is, grown for several years in the same field, continously, the soil borne pathogens of that, crop perennate in the soil and multiplies, increasing its population. Crop rotation will, not allow the pathogen to survive., –, Field sanitation : Necessary for the control, of soil borne, saprophytes and facultative, parasitic pathogens., –, Environmental modification : It includes the, modifications of such cultural practices, which discourage pathogen development, and help in reducing disease incidence and, loss in crop., Chemical control methods include the application, of chemicals to plants for the control of pathogens., The chemicals used oppose the germination,, growth and multiplication of the pathogen or, directly destroy it by toxicity., Depending upon the nature of pathogen, the, chemicals used are known as fungicides,, bactericides, insecticides, nematicides, viricides, and herbicides or weedicides. Commonly, they, are togetherly termed as pesticides., [For more on pesticides refer Chapter Pesticides, and Biofertilizers]., Biological control methods can be divided into, three categories –, –, Breeding resistance varieties : It is the, development of varieties having resistance, to pathogenic infection.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 620, , –, –, , ŕďőĽę– ĐĽŐńŐĹť, , Hyperparasitism : It involves the control of one, pathogenic organism with the help of another, organism parasitise or antagonize the pathogen., Trap crops and antagonism : Many plants, secrete some substances after infestation by, some pathogens, these substances become, toxic to the pathogens. Such hosts are called, traps or antagonistic plants., , Important plant diseases, l, , l, l, l, , l, l, , l, l, l, , l, , l, l, l, , l, , l, , Pathogens of damping off are Pythium,, Phytophthora,, Fusarium,, Rhizoctonia,, Helminthosporium, Colletotrichum., Damping off of tobacco is caused by Pythium., Damping off of groundnut is caused by, Rhizoctonia sps., If rotting occurs in a root it is called root rot. If, the root rot extends to the base of stem it is called, foot rot., Root rot affects the transport of water and mineral, nutrients. Leaves turn yellow due to root rot., Pathogens of root rot are Ophiobolus graminis,, Phymatotrichum omnivorum, Fusarium, moniliforme, Fusarium solani var phaseoli,, Thielaviopsis basicola, Sclerotium rolfsii., Thielaviopsis & Fusarium survive in the soil in, the form of chlamydospores., Sclerotium survives in the form of sclerotia., Host plants generally affected by root rot are –, wheat, barley, paddy, cotton, bean, potato,, tomato, carrot, beet., Loss of turgor leads to vascular wilting. The, petioles of lower most leaves droop due to this, disease and this phenomenon is called epinasty., Xylem vessels are blocked with fungal mats,, tyloses, gums., Bacteria and fungi grow in the vascular tissues causing, the non transportation of water and food materials., Toxins and pectinolytic enzymes produced by, these pathogens play an important role in, vascular wilting., Bacterial wilts are –, –, Wilt of maize, caused by Erwinia stewarti, –, Wilt of potato, caused by Pseudomonas, solanacearum., –, Wilt of sugarcane, caused by Xanthomonas, vasculorum., Fungal wilts are –, –, Wilt of cotton, caused by Fusarium, vasinfecti., , Wilt of redgram, caused by Fusarium, oxysporium., Downy mildews appears when the atmosphere is, with high humidity., Fungi causing downy mildews belong to the order, peronosporales., White cotton like or grey coloured, sporangiophores appear in clusters on the lower, side of the leaves., Downy mildew of sorghum is caused by, Sclerospora sorghi., Downy mildew of bajra is caused by Sclerospora, graminicola., Downy mildew of grapes is caused by, Plasmopara., Downy mildew of cucurbits is caused by, Pseudoperonospora., Downy mildew of millet is caused by Sclerospora, graminicola., Downy mildew of onion is caused by, Perenospora destructor., Powdery mildews are caused by fungi belonging, to the family Erysiphaceae (Class –, Ascomycetes)., Pathogens of powdery mildews are Erysiphe,, Sphaelotheca, Phyllactinia, Ansynula., Powdery mildew of wheat is caused by Erysiphe, graminis., Powdery mildew of rose is caused by, Sphaerotheca pannosa., The rust symptoms appears as small pustules of, rusty spores formed by bursting of host epidermis., Symptoms of rusts appear on vegetative parts., Fungi causing rusts belong to the order, uredinales (Class – Basidiomycetes)., Pathogens of rust are Puccinia, Uromyces,, Melampsora, Hemiliea., Host plants of rust are cereals, millets, coffee,, castor., Rust of wheat is caused by Puccinia graminis., Rust of pea is caused by Uromyces fabae., Rust of linseed is caused by Melampsora linii., Rust of coffee is caused by Hemilia vastatrix., Smut is named as smut due to sooty black spore, masses., Fungi causing smuts belong to ustilaginales, (Class : Basidiomycetes)., Symptoms of smut are usually found in the, reproductive organ., Pathogens of smut are Sphaecelotheca,, –, , l, l, l, , l, l, l, l, l, l, l, , l, l, l, l, , l, l, l, l, l, l, l, l, l, l, l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ńďňŚ– ▓ďŚĺŐńŐĹť, , l, l, l, l, l, l, l, , l, l, l, l, l, , l, , l, , l, , l, l, l, l, , Tolyposporium, Tilletia, Cladosporium,, Entyloma., Smut of jowar is caused by Sphaecelotheca, sorghi., Long smut of jowar is caused by Tolyposporium, ehrenbergi., The blighted host parts turn yellow and gradually, disintegrate., Pathogens of blight are Phytophthora,, Alternaria., Late blight of potato is caused by Phytophthora, infestans., Early blight of potato is caused by Alternaria, solani., Charcoal black coloured spotting on the, infected region like leaves and fruits are called, anthracnose., The causative fungi pathogen of anthracnose, belongs to Deuteromycetes., Acervuli are formed in these spots., Anthracnose disease of bean is caused by, Colletotrichum spp., Anthracnose of lime is caused by Gloeosporium, limetticola., In the region of the leaf spot the tissue shrinks, and separates from the healthy tissue leaving a, hole called shot hole., Pathogens of leaf spots are Cercospora,, Pseudomonas, Pyricularia, Helminthosporium,, Ascochyta, Botrytis., Leaf spot of groundnut is caused by Cercospora, personata. Leaf spot of cherry is caused by, Pseudomonas., Infected leaves show uneven thickenings, (wrinkles) due to abnormal multiplication of, palisade cells along the veins. It is called leaf, curl., Leaf curl of peach is caused by Taphrina, deformans., Witches broom of cherry is caused by Taphrina, cerasi., Crown galls of apple is caused by Agrobacterium, tumefasciens., The tumors that develop on root system by, nematodes are called root knots., , l, l, l, l, l, l, l, l, l, , l, l, l, l, l, , l, , l, l, , l, , l, l, , 621, , Root knot of tomato is caused by Meloidogryne, hapla (a nematode)., Canker is a dead area in the bark or cortex., Tumorous region of callus is present around the, canker., Citrus canker is caused by Xanthomonas citri, (a bacterium)., Apple canker is caused by Nectria galligena, (a fungus)., Ergot of rye is caused by Claviceps purpurea., Red rust of tea plant is due to Cephaleurous, (a parasitic alga)., Blast disease of rice is caused by Pyricularia, oryzae., External seed borne inoculum in blast of rice can, be eliminated by treating the seed with, organomercurial compounds like agrosan., Use of resistant variety is the most effective, method to prevent blast of rice., Red rot of sugarcane is caused by Colletotrichum, falcatum., The perfect stage of C. falcatum is Glomerella, tucumanensis., Tikka disease of groundnut is caused by, Cercospora sp., The main symptom of red rot of sugarcane is the, presence of red coloured elongated spots, developed in the midrib. Minute, black coloured, acervuli are present in these patches., Ireland famine of 184445 was due to late, blig ht of p otato cau sed by Ph ytop htho ra, infestans., Bengal famine of 1940's is due to the attack of rice, field by Helminthosporium oryzae., During 1867 1871 whole coffee plantations of Sri, Lanka were cut down due to the attack by coffee, rust caused by Hemileia vastatrix., In France, the whole wine industry was closed due, to the attack of grape vine by the fungus Plasmopora, viticola., Black heart of potatoes is due to poor ventilation, and high temperature., Tip burn disease of paddy leaves is due to reduced, oxygen supply and Zn deficiency.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 622, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 69, , Pesticides & Biofertilizers, PESTICIDES, l, , l, , l, , l, , l, l, , Pesticide may be a chemical substance or biological, agent (such as a virus or bacteria) used against, pests including insects, plant pathogens, weeds,, molluscs, birds, mammals, fish, nematodes, (roundworms) and microbes that compete with, humans for food, destroy property, spread disease, or are a nuisance., First commercial pesticide was discovered by, Millardet (1882). It is called Bordeaux mixture, (after the name of university)., Common household pesticides are baygon spray, (propoxur, a carbamate), finit/flit (having, malathion, an organophosphate), mosquito, repellent cakes and coils and BHC (benzene, hexachloride)., DDT (dichlorodiphenyltrichloroethane) is the, most well known because of its being the first, major synthetic pesticide and later its persistent, toxicity., Pesticides are generally biocides because they are, often broad spectrum., Pesticides includes chemical pesticides and, biopesticides., , Chemical pesticides, l, , l, , Chemical pesticides are very effective but are, poisonous chemicals and mostly non, biodegradable. Therefore they can cause, environmental pollution., It includes organochlorines, organophosphates,, carbamates, triazines etc. (Refer table)., , Biopesticides, l, , Biopesticides are certain pesticides derived from, natural or biological agents like animals, plants,, bacteria, viruses, fungi etc. to destroy or control, , l, , weeds, insects and pathogens., According to nature of organism – biopesticides, are of different types as microbial pesticides, plant, pesticides and biochemical pesticides., , Microbial pesticides, l, Microbial pesticides consist of a microorganism, (e.g., a bacterium, fungus, virus, or protozoan) as, the active ingredient., l, Microbial pesticides can control many different, kinds of pests, although each separate active, ingredient is relatively specific for its target pest(s)., l, For example, certain fungi control certain weeds;, other fungi kill specific insects., l, The most widely used microbial pesticides are, subspecies and strains of Bacillus thuringiensis, (Bt)., l, Each strain of this bacterium produces a different, mix of proteins and specifically kills one or only, a few related species of insect larvae., l, Whereas some species of B. thuringiensis control, moth larvae found on plants, others are specific for, larvae of flies and mosquitoes., l, The target insect species are determined by whether, the particular Bt produces a protein that can bind, to a larval gut receptor, thereby causing the insect, larvae to starve., l, Microbial insecticides are applied as sprays, dusts,, or granules just as conventional pesticides., l, Microbials may kill insects a little more slowly, than do conventional pesticides., Plant pesticides, l, Plantpesticides [Plant incorporated protectants, (PIPs)4] are pesticidal substances that plants produce, from genetic material that has been added to the, plant.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ĚřŚĽĘĽęĚř– ·– ▲ĽŐěĚথńĽŮĚŕř, , A systemic pesticides is a pesticides applied to a, plant which is absorbed into its sap and so, distributed throughout the plant to make all parts, of it poisonous to pests, without harming the plant,, although systemic insecticides which poison pollen, & nectar in the flowers may kill needed pollinators., l, , Biochemical pesticides, l, Biochemical pesticides are naturally occurring, substances that control pests by nontoxic, mechanisms., l, Conventional pesticides, by contrast, are generally, synthetic materials that directly kill or inactivate, the pest., l, Biochemical pesticides include substances such as, insect sex pheromones that interfere with mating, as well as various scented plant extracts that attract, insect pests to traps., l, Biochemical products also include hormones such, as growth regulators and enzymes., l, Insect growth regulators (IGRs) are nontoxic., They disrupt the balance in the insect between, juvenile hormone, which regulates development,, and the hormone that regulates emergence into, adulthood, causing abnormal pupation or adult, development., l, According to nature of action biopesticides are, of various types are as bioherbicides and, bioinsecticides., l, Bioherbicides are those organisms or their extracts, that destroy weeds without harming useful plants., l, Bioherbicides are of various types –, –, Predator herbivore : Specific insects that, feed on weeds. Cactoblastis cactorum, (Cochineal insect) has controlled spread of, Opuntia in India and Australia. Chrysolina, beetles have overcome Klamath weed, (Hypericum perforatum) in U.S.A. Beetle, Zygogramma bicolorata is biological control, of Parthenium hysterophorus., , Smoother crops : Crops that do not allow, weed to grow, e.g., sunflower, soyabean,, barley, rye, sorghum, etc. Rotation with such, crops gives protection from weed., –, Mycoherbicides (first bioherbicides) : Fungi, that are used as herbicide. Phytophthora, palmivora does not allow milkweed vine to, grow in Citrus orchards. ‘Devine’ and, ‘Collego’ are fungal spores which can be, sprayed over weeds for their elimination., –, Transgenic crops : They are crops having, genes of smoother crops, pest and herbicide, resistance, e.g., transgenic tomato (against, Hornworm larvae), transgenic tobacco (against, herbicides)., –, Vegetables : Certain weeds can be eliminated, or made useful by using them as vegetable or, fodder, e.g., Amaranthus, Chenopodium., Bioinsecticides are organisms or their products, which are used to kill or repel specific insects., They are of different types – predators, parasites, and pathogen, sterile male, insect hormones and, natural insecticides., Predators are specific natural organisms that are, introduced to control plant pests without harming, useful insects. Lady bug and praying mantis can, control scale insects or aphides of vegetables,, cotton and apple. Vedalia beetle (Radiola, cardinalis) of Australia has been used in several, countries against cottony cushion scale. Predator, bug has been successfully employed in Hawaii in, controlling sugarcane leaf hopper (Perkinsiella, saccharicida)., Parasites are organisms that feed on other living, organisms (hosts) without devouring them., Parasitoids are organisms that live a parasitic life, in younger stages (egg and larval) but lead a free, life later on., Pathogens are disease producing microorganisms., Egg parasitoids of Trichogramma are able to control, a number of pests of cotton, sugarcane and pulses., Fungus Bauveria bassiana can control potato beetle, and codling moth, fungus Entomophthora ignobilis, green peach aphid, bacterium Bacillus thuringiensis, cabbage looper (Trichoplausian), bacterium, Bacillus popilliae causes milky diseases in Japanese, Beetle Popilia (which is a serious pest of vegetable, and fruits) and virus Baculovirus heliothis Cotton, –, , For example, scientists can take the gene for the Bt, pesticidal protein and introduce the gene into the, plant’s own genetic material. Then the plant, instead, of the Bt bacterium, manufactures the substance, that destroys the pest. Both the protein and its, genetic material are regulated by the, Environmental Protection Agency (EPA); the, plant itself is not regulated., , l, , l, , l, l, , l, , 623
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 624, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , Bollworm (Heliothis zea)., Sporeine developed in Germany is the first, commercial bioinsecticide obtained from Bacillus, thuringiensis., A large number of sterile males are introduced that, mate without producing offsprings., Insect hormones are different types of hormones, used for controlling pests, like –, –, Juvenile hormone : Does not allow insect to, reach maturity., –, Pheromone : Biochemicals used to disrupt, mating behaviour of insects. Pheromone traps, like cylindrical traps coated internally with, female pheromones will attract all males. In, confusion pheromone technique small paper, pieces having female pheromones are thrown, over the area. Males will not be able to locate, females., –, Moulting hormone : It causes premature, moulting of larvae resulting in death., Natural insecticides : Refer table : Types of pesticides, (natural insecticide) on page no. 626627., , often kill predators or higher trophic level, organisms, bringing about ecological imbalance., (Environmental Protection Agency`)., Integrated pest Management (IPM), IPM involves use of different pest control, methods, which are ecologically sound (i.e., not, cause hazard to environment), e.g., biological, control methods, better agricultural practices like, crop rotation, sanitation, etc., starvation method,, i.e., growing of target crop away from major, crop, ultra low volume spraying method, i.e.,, use of very low and most effective concentration, of chemicals, which does not cause pollution,, etc., Organic farming, It is the technique of raising crops through the, use of manures, fertilizers and pesticides of, biological origin, resistant varieties, crop, rotation, intercropping etc. It gives unpolluted, plant and animal products., Sustainable agriculture, It is the practice of obtaining optimum, agricultural yield as per changing human needs, while maintaining or enhancing the quality of, environment and conserving natural resources, through judicious management of available, resources., , Hazards caused by use of pesticides, l, l, , l, , l, , l, l, l, , l, l, , Storage – Opened pesticide cans/bottles may poison, food, stored fodder, implements, etc., Field workers/sprayers – Pesticides are inhaled,, absorbed or ingested by persons involved in their, spray., Factory accidents – Any slackness in control leads, to accidents like the one at Bhopal (methyl, isocyanate) in 1984 in Union Carbide Plant,, Bolsover England (1968) and Soverso Italy (1976)., Pesticide treadmill – It is the phenomenon of, requirement of progressively larger and larger doses, with the passage of time., Persistance – Most pesticides degrade very slowly, and persist., Resistance – Pests tend to develop resistance to, pesticides., Biomagnification/Bioconcentration – This is, increase in percentage of a chemical in the body of, organisms with the rise in trophic level. Most, organochlorines are fat soluble and undergo, biomagnification (13 31ppm of DDT in human, body in India)., Biocides – Pesticides are biocides and kill even the, nontarget organisms., Ecological imbalance – Being biocides, pesticides, , FERTILIZER, l, , l, , l, l, , l, l, l, , l, , Fertilizers are inorganic materials containing, elements in the form of soluble or readily available, chemical compounds., Fertilizer is a substance that is added to the soil or, provided as foliar spray in order to provide required, nutrients to plants., It is of two types chemical and biological., Chemical fertilizers are synthetic or chemical, formulations that supply the soil with requisite, minerals directly., Mostly they are inorganic (eg., calcium ammonium, nitrate etc.)., Chemical fertilizers are mostly synthesized from, fossil fuels., To increase agricultural productivity, chemical, fertilizers and pesticides are being used by the, farmers on a large scale., The ill effects of chemical fertilizers are –
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 626, , Types/Names, , ŕďőĽę– ĐĽŐńŐĹť, , Examples, , Character/effect, , –, , Pyrethroids synthetic derivatives of, pyrethrum (pyrethrin), e.g., allethrin, cyclethrin, & barthrin, , Volatile liquid (fumigant), Poisonous, kill insects,, nematodes & other animals or, plants that damage stored foods, or seeds, human dwellings etc., , Ethyl dibromide, , 5. Nematicides, , Chemicals, nematodes, , Methyl bromide, ethylene dibromide, chloropicrin., , 6. Rodenticides, 7. Bactericides, , Chemicals that kill rodents, Chemicals used for control of, bacteria as –, , Sodium fluroacetate, warfarine, zinc sulphate, , Disinfectants, , – Active chlorine, active oxygen, iodine, alcohols etc., , that, , destroy, , Antibiotics, , – Blasticidin, agrimycin, streptomycin, viridin, , 8. Virucides, , Chemicals used to control, viruses, , – Imaniun, , 9. Miticides, , Chemicals used to control mites, , Phomix, fluvalinate, , –, –, , l, , l, l, , l, , l, , They are expensive, Their manufacture depends upon the, dwindling resources of energy as petroleum, and coal etc, –, Their production releases pollutants, –, They are lost readily when applied in field by, surface run off and thus pollute soil & other, water resources., Biological fertilizers are nutrient materials obtained, from living organisms or their organic remains, which are used for enhancing fertility of soils., Biological fertilizers are of two types manures, & biofertilizers., Green manures, biofertilizers and biological control, methods have been introduced to combat the ill, effects of agricultural chemicals., Agricultural chemicals are chemicals employed, in agriculture for protecting crop plants from pests, and enhancing the yield of crop plants by meeting, their nutritional requirements., They include chemical fertilizers, growth, regulators and pesticides., , MANURES, l, , Manure is a semidecayed organic matter which is, added to the soil in order to maintain its fertility,, , l, l, , l, , l, , l, , crumb structure, aeration and hydration capacities., It is of three types farmyard manure, compost, and green manure., Farmyard manure Dung, farm refuse, fallens, leaves, twigs, etc. are dumped in heaps to undergo, decomposition and form dark amorphous manure., Compost/composited manure is rotten vegetable, matter, garbage, sewage sludge and animal refuse, often enriched with small amount of chemical, fertilizers during decomposition stage., Ghai and Thomas (1989) have defined green, manuring as ‘a farming practice where a, leguminous plant which has derived enough, benefits from its association with appropriate, species of Rhizobium is ploughed into the soil and, then a non legume is grown and allowed to take the, benefits of the already fixed nitrogen., Various leguminous plants to be used as green, manure are : cultivated annual legumes (e.g.,, Crotalaria juncea, C. striata, Cassia mimosoides,, Cyamopsis pamas, Glycine wightii, Indigofera, linifolia, Sesbania rostrata, Vigna radiata),, perennial legumes (e.g., Acacia nilotica, Cassia, hirsuta, Sesbania aegyptica, Leucaena, leucocephala), and wild annual legumes (e.g.,, Cassia cobanensis, Lathyrus sativus, Mimosa, invisa, Mucuna bacteata).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ĚřŚĽĘĽęĚř– ·– ▲ĽŐěĚথńĽŮĚŕř–, l, , l, l, , In India, for small and marginal farmers, green, manuring may be important because of high cost, of chemical fertilizers., Moreover, reclamation of “Usar lands” can also be, done by green manuring., In addition to nitrogen, green manures also, provide organic matter, N, P, K (nitrogen,, phosphorus, potassium) and minimize the, number of pathogenic microorganisms in soil., , –, , l, , BIOFERTILIZER, l, , l, , l, , l, , l, , l, , Biofertilizers are ready to use live formulates of, such beneficial microorganism which on, application to seed, root or soil mobilize the, availability of nutrients by their biological activity, in particular and help build up the micro flora and, in turn the soil health in general., Nitrogenous biofertilizers harvest atmospheric, nitrogen and converts into ammonical form, which, in due course is made available to the plants or is, released in the soil., Phosphate solutions solubilize fixed forms of, phosphorus already present in the soil and make it, available for use of plants., Compositing biofertilizers are used for hastening, the process of compositing and for enriching its, nutrient value., With the introduction of green revolution, technologies the modern agriculture is getting more, and more dependent upon the steady supply of, synthetic inputs (mainly fertilizers) which are, products of fossil fuel (coal + petroleum)., Excessive dependence of modern agriculture and, the supply of these synthetic inputs and the adverse, effects being noticed due to their excessive and, imbalanced use has compelled the scientific, fraternity to look for alternatives., , Advantages of biofertilizers over chemical, fertilizers, l, l, , Availability and cost : Increasing costs are getting, unaffordable by small and marginal farmers., Effect of chemical fertilizers in soil and, environment., –, Excessive and imbalanced use of chemical, fertilizers has adversely affected the soil, causing decrease in organic carbon, reduction, in microbial flora of soil, increasing acidity, and alkalinity and hardening of soil., , 627, , l, , l, , l, , Excessive use of Nfertilizer are contaminating, water bodies thus affecting fish fauna and, causing health hazards for human beings and, animals., –, Production of chemical fertilizers adds to the, pollution., To overcome the deficit in nutrient supply and to, overcome the adverse effects of chemical cultivation, it is suggested that efforts should be made to exploit, all the available resources of nutrients under the, theme of integrated nutrient management., Under this approach the best available option lies, in the complimentary use of biofertilizers, organic, manures in suitable combination of chemical, fertilizers., This integrated approach of nutrient management, not only ensures higher productivity but also ensures, the good health of our soil and environment., Biofertilisers are essential components of this, approach and are being promoted to harvest the, naturally available, biological system of nutrient, mobilization., , Types of biofertilizers, l, , l, , l, , For nitrogen, –, Rhizobium for legume crops, –, Azotobacter/Azospirillum for nonlegume, crops, –, Acetobacter for sugarcane only, –, BGA and Azolla for low land paddy, For phosphorus, –, Phosphatika for all crops to be applied with, Rhizobium, Azotobacter, –, Azospirillum and Acetobacter, For enriched compost, –, Cellulolytic fungal culture, –, Phosphotika and Azotobacter culture, , Micro-organisms used as biofertilizers, l, , l, , Bacteria, cyanobacteria (blue green algae) and fungi, are the different types of organisms that act as, biofertilizer., Bacteria and cyanobacteria (also Frankia) are known, to fix atmospheric nitrogen while mycorrhizal fungi, draw nutrients from organic matter to provide to the, plant with which it is associated., , Bacteria as biofertilizers, l, There are three major categories of bacteria that, are used as biofertilizers.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 628, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Free living nitrogen fixing bacteria, –, These are bacteria of diverse nutritional status, which absorb molecular nitrogen (N2) from, soil, air and convert it into nitrogen salts or, amino acids., –, They include the following : Azotobacter,, Beijerinckia aerobic, Clostridium anaerobic, Rhodospirullum & Chromatium photosynthetic., Symbiotic nitrogen fixing bacteria, –, These bacteria form a mutually beneficial, associations with the plants., –, The bacteria obtain food & shelter and in turn, help the plants to obtain nitrogen by fixing it., –, The most important of such type is Rhizobium, leguminosarum which forms nodules on the, roots of legume plants., –, The other species of Rhizobium are R. lupini,, R. trifolii, R. phaseoli, R. meliloti., –, A root nodules has a growing point, vascular, strand and reddish pigment leghaemoglobin, but lacks root cap and root hair., –, Its central infection zone has large cells with, groups of bacteroids covered by membrane, lined by leghaemoglobin., –, Frankia is present in root nodules of, nonleguminous plants, e.g., Casuarina, Alnus,, Myrica, Rubus., –, In Sesbania the stem nodule contains, Aerorhizobium caulinodans, Xanthomonas is, present in leaf nodules of Ardisia., Phyllosphere and Rhizosphere nitrogen fixing, bacteria (loose association)., –, These bacteria live freely around roots and, leaves of higher plants without any intimate, relationship., –, They provide the nitrogen fixed to the plants, and obtain their nutrition from the exudations., –, This relationship is termed as associative, mutualism., , Cyanobacteria as biofertilizers, l, Cyanobacteria or blue green algae are the simplest, living autotrophic plants that act as biofertilizers, which are of extremely low costs., l, Cyanobacteria derive the energy needed for nitrogen, fixation through photosynthesis., l, They are of 2 main types free living & symbiotic, nitrogen fixing bacteria., , l, , l, , Free living nitrogen fixing cyanobacteria, –, They increase nitrogen content of the moist, soil and water bodies., –, The most important nitrogen fixing, cyanobacteria are Anabaena, Nostoc,, Aulosira, Tolypothrix, Stigonema., –, Aulosira fertilissima is the most active, nitrogen fixer of rice fields., –, Cylindrospermum licheniforme grows in, sugarcane and maize fields., Symbiotic nitrogen fixing bacteria, –, Nitrogen fixing cyanobacteria form symbiotic, associations with many plants like Cycas roots,, lichens, liverworts, Azolla etc., –, Azolla pinnata is a small aquatic fern added, to the rice fields of SouthEast Asia., –, It contains symbiont Anabaena azollae in its, leaf cavities which fixes atmospheric nitrogen., –, A part of this nitrogen is excreted in the, cavities for use of the fern., –, The ferns in turn give this to the rice field, while decay., , Fungi as biofertilizers/mycorrhiza, l, Mycorrhiza (fungus roots) is a distinct, morphological structure which develops as a result, of mutualistic symbiosis between some specific, rootinhabiting fungi and plant roots., l, Plants which suffer from nutrient scarcity,, especially P and N, develop mycorrhiza i.e., the, plants belong to all groups, e.g., herbs, shrubs, trees,, aquatic, xerophytes, epiphytes, hydrophytes or, terrestrial ones., l, In most of the cases plant seedling fails to grow if the, soil does not contain inoculum of mycorrhizal fungi., l, The shape of the root is irregular or coralloid with, wooly covering but no root hairs or root cap., l, Mycorrhiza helps in absorption of water, minerals, from organic matter and protection from soil borne, pathogenic fungi., l, Depending upon the location of the fungus, mycorrhiza are of two types ectomycorrhiza and, endomycorrhiza., l, Ectomycorrhiza, –, It is found among gymnosperms and, angiosperms. In short roots of higher plants, generally root hairs are absent. Therefore, the, roots are infected by mycorrhizal fungi which,, in turn, replace the root hairs (if present) and, form a mantle.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▓ĚřŚĽĘĽęĚř– ·– ▲ĽŐěĚথńĽŮĚŕř, , –, , l, , The hyphae grow intercellularly and develop, Hartig net in cortex. Thus, a bridge is, established between the soil and root, through the mycelia., –, The root cells secrete sugar and nutrients into, the intercellular spaces for fungal feed, e.g., Eucalyptus, oak, peach, pine etc., –, The main functions of these fungi are, absorption of water, solubilization of organic, matter of the soil humus, release of inorganic, nutrients, absorption and transfer to roots., –, Plants with ectomycorrhiza are known to, absorb 23 times more of nitrogen,, phosphorus, potassium and calcium., –, The fungus secretes antimicrobial substances, which protect the young roots from pathogen, attack., Endomycorrhiza, –, The morphology of endomycorrhizal roots,, after infection and establishment, remain, unchanged., –, Root hairs develop in a normal way., –, The fungi are present on root surface, individually., –, They also penetrate the cortical cells and get, established intracellularly by secreting, extracellular enzymes., –, Endomycorrhizas are found in all groups of, plant kingdom, eg., grasses, crop plants,, orchids and some woody plants., –, Intercellular growth occurs in order to, obtain nourishment because unlike, ectomycorrhiza, the cortical cells do not, secrete sugars in the intercellular spaces., –, The hyphal tips passing into cortical cells, either produce swollen vesicles or finely, branched masses called arbuscules., –, The major benefits of VAM (vesicular , arbuscular mycorrhiza) to the plant is the, supply of inorganic nutrients as well as, enchanced water absorption., –, Phosphate which is mostly present in the, unavailable form in the soil, becomes, abundantly available to the plant., , Utility of biofertilizers, l, l, , It is a low cost and easy technique, and can be used, by small and marginal farmers., It is free from pollution hazards and increase, soil fertility., , l, , l, , l, l, l, , l, , l, , 629, , On application of algal biofertilizers increase in, rice yields ranges between 10 45 per cent and, about 40 50 kg N is left over in the soil which, in turn is used for the subsequent crops., Cyanobacteria secrete growth promoting substances, like IAA, IBA, NAA, aminoacids, proteins,, vitamins, etc. They add sufficient amount of organic, matter in soil., Rhizobial biofertilizers can fix 50 150 kg N/ha/, annum., Azotobacter and Azospirillum, besides supplying, N to soil, secrete antibiotics which act as pesticides., Azolla supplies N, increases organic matter and, fertility in soil and shows tolerance against heavy, metals., The biofertilizers increase physicochemical, properties of soils such as soil structure, texture,, water holding capacity, cation exchange capacity, and pH by providing several nutrients and sufficient, organic matter., The mycorrhizal biofertilizers make the host plant, available with certain elements, increase longevity, and surface area of roots, reduce plant response to, soil stresses, and increase resistance in plants. In, general, plant growth, survival and yield are increased., , Precautions, l, l, l, l, l, , l, l, l, l, l, , Biofertilizer packets should be stored in cool and, dry place away from direct sunlight and heat., Right combination of biofertilizers must be used., Rhizobium is crop specific, so should be used in, specified crop., Should not be mixed with chemicals., While purchasing ensure that each packet is, provided with necessary information like name of, the product, name of the crop for which intended,, name and address of the manufacturer, date of, manufacture, date of expiry, batch No and, instructions for use., Packet should be used before expiry, only on the, specified crop, by the recommended method., Biofertilizers are live product and require care in, storage., For best results both nitrogenous and phosphatic, biofertilizers must be used., Use of biofertilizers is being emphasized along with, chemical fertilizers and organic manures., Biofertilizers are not replacement of fertlizers but, can supplement their requirement.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 630, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 70, , Mental health, Addiction, and Community Health, l, l, , l, l, , l, , l, , l, , l, , l, , l, , l, , Mental health is an important aspect of, physiological health & social effectiveness., Mental illness of a person is characterized by his, abnormal behaviour and talk causing distress and, suffering both to the person and people around him., Mental illness can be classified into three types :, psychosis, neurosis and epilepsy., Psychosis is a severe mental disorder in which the, individual loses contact with reality (madness), not, aware of his illness, refuses to take help., A person suffering from psychosis is incapable of, functioning normally in society and usually requires, hospitalization., Neurosis is a mild type of mental illness with, excessive or prolonged emotional reactions (anger,, fear, sadness, vague aches, etc.)., Phobias are generally associated with neurosis., Neurotic people remain in touch with reality and, seek help., These disorders (psychosis & neurosis) are, categorised into following types like anxiety,, obsessive compulsive disorder (OCD), depression, etc., Anxiety are a diverse group of disorders including, neurotic anxiety (an over reaction to stressful, events associated with bodily symptoms like, palpitation, sweating, nausea, trembling, diarrhoea, and muscular tension), separation anxiety and, school phobia., Obsessivecompulsive disorders are characterised, by compelled performance of an action/idea despite, attempt to resist it, e.g., violence, constant doubts,, concern about infection by germs/dirt., Attention deficit disorder occurs more in boys than, in girls, which exhibits under achievement,, behavioural problems and a tendency to be disliked, by other children., , l, , l, , l, , l, l, , l, , Mood disorders are characterised by occassional, doubts of high or low mood. These include, depression which is characterised by sadness,, hopelessness, low self esteem, decline in interest, and concentration and change in sleep pattern and, appetite, its cause may be death in family, failure, in examination/interview or losing a job, the, depressed mood may alternate with over activity, like quick talking, talking multiple tasks at the same, time and endogenous depressions which arise from, internal, biochemical or genetic factors, and are, symptomised by lethargy, self hatred, irratic sleep, pattern and uncontrollable weeping., Border line personality disorder (BPD) is, characterised by unpredictable moods, outbursts of, emotion, quarrel some behaviour and conflicts with, others. Individuals with BPD often attempt to injure, or kill themselves and have little sense of self., Epilepsy is usually characterised by fits of, convulsions, the person loses consciousness and, falls down., Parkinson’s disease is a sporadic disorder of, middle and late life., Parkinson’s disease is characterised by stooped, posture, stiffness and slowness of movements, fixity, of facial expression and rhythmic tremor of limbs, (most pronounced in hands) which subsides on, relaxation or actively willed movement., Parkinson’s disease is caused by development of, melanin containing nerve cell aggregates in brain, stem with varying degree of nerve cell loss, Lewy, bodies (eosinophilic, rounded concentrically, laminated inclusions, Lewy 1913) in the cells and, reduced secretion of dopamine in dopamine, containing regions of brain.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▐ĚňŚďń– ŘĚďńŚĺΘ– ○ęęĽĘŚĽŐň– ďňę– ►ŐŇŇśňĽŚť– ŘĚďńŚĺ–, l, , l, l, , l, , l, , l, , l, , l, , l, l, l, , l, , l, , Alzheimer’s disease is a progressive degenerative, disease of brain which is caused by senile plaques, and neurofibrillary tangles resulting in loss of, choline acetyltransferase activity., Alzheimer’s disease commonly appears after the, age of 40, though it can occur in any age group., Schizophrenia is a type of mental illness or, psychotic disorder which is characterised by, progressive deterioration of personality,, shallowness of emotional life, auditory, hallucinations, delusions, illogical thinking, sense, of being influenced by others and feeling of being, controlled by outside forces., Schizophrenia can be caused by excessive, dopamine production, alterations in, neuropeptides, increased ventricular brain ratios and, decreased frontal lobe activity., The main causes of mental illness are : changes in, the brain, hereditary factors, childhood experiences,, home atmosphere and special factors., Antipsychotic drugs like phenothiazine and, lithium are used to calm or sedate the cases of, acute psychoses., Most antipsychotic drugs block the action of, dopamine, a chemical that stimulates nerve activity, in the brain., Shock treatment (ECT) is suited in some cases and, can bring about dramatic improvement in severe, depression., Psychotherapy also assists a person in adjusting, himself to the surroundings., Social therapy (rehabilitation) has an important, role to play., Psychology is study of the behaviour of man and, animals, and related mental and physiological, processes., Psychiatry is a branch of medicine dealing with, diagnosis, treatment and prevention of mental, disorders., Mental health services in a community are, concerned not only with early diagnosis and, treatment, but with the preservation and promotion, of mental illness. The mental health services, comprise –, –, Early diagnosis and treatment, –, Rehabilitation, –, Group and individual psychotherapy, –, Mental health education, , l, , 631, , –, Use of modern psychoactive drugs, –, Aftercare services, Mental hygiene is scientific study and application, of methods to reserve and promote mental health., , ADDICTION, l, l, , l, l, l, , l, , l, , l, l, l, , l, , l, l, l, , l, l, l, , The term ‘addiction’ refers to a dependence on, and, craving for, tobacco, alcohol or a particular drug., Addictive disorders are the state of body when it, requires continuous presence of psychoactive, substance within it., Tobacco is the dried leaves of the plant Nicotiana, tabacum and N. rustica (family solanaceae)., Nicotine is the substance that causes addiction to, tobacco., Nicotine acts as a tranquillizer, but also stimulates, the release of adrenaline leading to high blood, pressure., Nicotine is highly poisonous; nicotine present in, a cigarette is sufficient to kill a person if injected, intravenously., Nicotine (a) stimulates passage of nerve impulses,, (b) causes muscles to relax, (c) causes increased, heart rate., In pregnant women, nicotine causes retardation of, the growth of foetus., Tobacco smoke contains – carbon monoxide,, polycyclic aromatic hydrocarbons, and tar., The main harmful effects of smoking are, respiratory diseases (lung cancer, bronchitis and, emphysema) and cardiovascular diseases, (coronary artery disease and peripheral vascular, disease)., Smokers can expect to live about ten years less than, the nonsmokers. Smoking causes greater illhealth, than any other drug., One of the common cancers attributed to cigarette, smoking is lung cancer., Mouth cancer is commonly found among tobacco, chewers., The withdrawal symptoms includes irritability,, anxiety, craving, sleep problems, headache, termor, & lethargy. It may continue for 46 weeks & craving, may continue for many month., Central Tobacco Research Institute is situated at, Rajahmundry (A.P.), China has the biggest cigarette market., Antitobacco Day is celebrated on May 31.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 632, , l, , l, l, l, , l, l, , l, , l, , l, , l, , l, l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Ethanol or ethyl alcohol is the active constituent, of alcoholic drinks such as beer (5 per cent by, volume), wine (10 per cent by volume) and whisky, (40 per cent by volume)., In medicine, alcohol is used as an antiseptic and, a solvent., Low level of alcohol causes facial flushing,, talkativeness and increases social confidence., High level of alcohol causes disturbed thinking,, irritability, reduced selfcontrol, slurred speech,, drowsiness, difficulty in remaining upright, etc., Alcohol decreases the activity of CNS, thereby, reducing anxiety, tensions and inhibitions., Alcohol decreases the secretion of ADH (anti, diuretic hormone) from posterior pituitary causing, increased urine output., Heavy drinkers become dehydrated. Thirst, dry, tongue and hangover are associated with effects of, alcohol., In the liver, alcohol is converted into a more toxic, substance, acetaldehyde, which is used by cells for, energy., Liver synthesises fats from alcohol; the extra fat, decreases the production of enzymes and structural, proteins., The accumulation of fat results in ‘fatty liver, syndrome’ leading to cirrhosis (replacement of, liver cells by fibrous tissue)., Alcohol addiction lowers blood sugar level,, adversely affecting the brain., Alcohol and driving do not go together as alcohol, causes –, –, Reduced ability to judge distance,, –, Reduced coordination of limbs, head and eyes,, –, Reduced alertness,, –, Reduced field of vision (tunnel vision),, –, Increased reaction time,, –, Changed behaviour., Physicians prescribe drugs to prevent or cure, diseases or otherwise enhance physical and mental, welfare., These drugs have sedative or intoxicative effects, on the body. Constant & regular use of these drugs, forms a habit and once acquired it becomes very, difficult to leave these habits. This condition is, called as drug dependence., Drug abuse is defined as self administration of a, drug for nonmedical reasons. Abused drug include, , l, , l, , l, l, , l, l, , l, l, l, l, l, l, , l, , l, l, l, l, , l, l, l, , anabolic steroids, analgesics and antibiotics., Drugs are classified on the basis of their way of, production in two classes : natural drugs and, synthetic drugs., Drugs are also classified on the basis of their mode, of action on brain into two categories –, –, Psychoactive or psychotropic drugs, –, Psychedelic or hallucinogenic drugs, Psychoactive or psychotropic drugs are also called, as mood altering or neurological drugs., Psychedelic or hallucinogenic drugs produce, psychological effect like illusions and, hallucinations., Psychotropic drugs act on the brain and alter the, behaviour, consciousness and powers of perception., Four categories of psychotropic drugs are –, sedatives and tranquillizers, opiate narcotics,, stimulants and hallucinogens., Sedatives and tranquillizers have a depressing, (switching off) effect on the activity of the brain., Sedatives may produce a feeling of calmness,, relaxation or drowsiness., In higher dose, sedatives induce deep sleep., Tranquillizers reduce tension and anxiety without, inducing sleep., Opium is obtained from the unripe seed pods of, the poppy plant, Papaver somniferum., Opium has an analgesic (painkilling) effect and, may also reduce anxiety and tension, and lowers, the blood pressure and breathing rate., Opium and its derivatives, which include, morphine, codeine and heroin are among the drugs, collectively known as narcotic drugs., Morphine has sleep and dream inducing properties., Codeine is milder than morphine and used in, cough syruph., Narcotics induce addiction if used repeatedly and, heroin is the most dangerous narcotic., Another opium derivative is brown sugar,, chemically known as diacetylmorphine, hydrochloride., Stimulants are also known as ‘mood elevators’., Stimulants increase nerve activity in the brain by, initiating the release of noradrenaline., There are two main groups of stimulant drugs:, central nervous system stimulants (e.g.,, amphetamine drugs) and respiratory stimulants, (e.g., analeptic drugs).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 633, , ▐ĚňŚďń– ŘĚďńŚĺΘ– ○ęęĽĘŚĽŐň– ďňę– ►ŐŇŇśňĽŚť– ŘĚďńŚĺ–, l, , l, , l, l, l, l, , l, , l, , l, , l, l, l, , Mildest among the stimulants is caffeine which is, commonly taken in the form of tea, coffee and cola, drinks., Caffeinism is caffein intoxication characterized by, restlessness, nervousness, excitement, insomnia,, gastrointestinal complaints, etc., Amphetamines and cocaine are strong stimulants., Cocaine is obtained from the leaves of Erythroxylon, cocca., “Crack” is a purified form of cocaine; it can cause, seizures and cardiac arrest., Hallucinogens include certain drugs of abuse, also, called psychedelic drugs, such as LSD, marijuana,, mescaline and psilocybin., These drugs have a strong effect on cerebrum and, sense organs and take the user to a world of fantasy, giving him false and temporary happiness., LSD (lysergic acid diethylamide) is one of the, most dangerous hallucinogens of modern times, derived from Ergot fungus, Claviceps purpurea., The products of hemp plant, Cannabis sativus, like, bhang, marijuana, ganja, hashishcharas, etc. are, other examples of hallucinogens., Reserpine alkaloid is obtained from the roots of, Rauwolfia serpentina (family apocynaceae)., Reserpine is used for the treatment of blood, pressure, snake bite and mental disorders., The drug belladona is extracted from the dried, leaves and roots of Atropa belladona (family, solanaceae)., , l, , l, , l, , l, , l, , l, , l, , Belladona is a narcotic, d iuretic and, antispasmodic. Leaves contain atropine, used to, dilate pupil of eye., Mode of Drug Action. Drugs act at the synapses, by inhibiting (depressants) or accelerating, (stimulants) secretion of neurotransmitter., Pharmacology is the science dealing with drugs,, their sources, appearance, chemistry, actions and, uses., Community health services give special attention, to –, –, The sanitation of environment, –, Prevention and control of communicable, diseases, –, Maternal and child health, and family welfare, –, School health services., Universal immunization programme was, launched by W.H.O. in 1974 for the global, immunization of children to protect them from six, preventable diseases, i.e., diphtheria, whooping, cough (pertussis), tetanus, polio, tuberculosis and, measles., MMR vaccination programme was launched, in India for the first time on 14th November, 1999., This vaccine which is to be given to all children, above 15 months of age only once, gives life long, and complete protection from dreaded diseases like, Measles, Mumps and Rubella., , Table : National immunization schedule, Age, , Vaccine, , Disease, , 3 – 12 months, , DPT, , 3, , Polio (Sabins oral), BCG (intradermal), , Diphtheria, Pertussis (Whooping cough), and Tetanus, Poliomyelitis, Tuberculosis, , 9 – 15 months, , Measles, , Measles, , 1, , 18 – 24 months, , DPT, , Diphtheria, Pertussis and Tetanus, , 1, , Polio (oral), , Number of doses, , 3, 1, , 1, , 5 – 6 years, , DT, Typhoid vaccine, , Diphtheria, Tetanus and Typhoid, , 1, 2, , 10 years, , Tetanus toxide, Typhoid vaccine, , 1, 1, , 16 years, , Tetanus toxoide, Typhoid vaccine, , 1, 1
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 634, , ŕďőĽę– ĐĽŐńŐĹť, , ADOLESCENCE, l, , l, l, , l, l, , l, , The period of rapid growth, the physical and mental, development poised between childhood and, adulthood (between 818 years for girls and 719, years for boys) is called adolescence., The period of adolescence extends from puberty to, complete sexual maturity., Changes taking place during adolescence are –, accelerated physical growth and development of, reproductive organs; changes in functioning to the, neuroendocrine system; shift of moods and, emotional turbulance prompted by increased, production of hormones, including sex hormones;, and self assertion (egocentrism), and concurrent, developments of selfidentity, self esteem and self, respect., Common problems of adolescence are – acne,, phobias and post traumatic stress disorders., Acne (pimples) results from clogged pores of skin, due to a side effect of the influx of sex hormone,, androgen which increases self conciousness., Hypochondria is a form of anxiety and, psychosomatic disorder characterised by undue, concern about health., , l, , l, , l, l, , l, , l, , Neurosthenia is characterised by the inability to, concentrate on or enjoy things, and may lead to, irritability, fatique, insomnia, depression and, headache., Physiological aberrations including absence of, monthly periods in females or perpetual, disturbances., Phobias are intense dread of things or creatures or, situations like crowded places, vast open places etc., Post traumatic stress disorder are due to traumatic, experiences like rape or robbery. In such cases, surviving victims and bystanders are affected, equally., Addiction to drugs, tobacco and alcohol is also, common among adolescents. The main reasons of, addicition are curiosity, advertisements, peer, pressures, frustration and depression, feeling of, independence, false belief of enhanced physical, mental/intellectual performance., Social and moral implications. During, adolescence an individual moves out from the, familial periphery and begins to identify and define, his/her position in relation to the outer world. He, undergoes physiological and behavioural, transformations, and acquires higher levels of moral, standings.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▀ŇŇśňĚ– ☼ťřŚĚŇ– ·– ▼ĚěĚňĘĚ– ▐ĚĘĺďňĽřŇř, , 635, , Chapter 71, , Immune System & Defence, Mechanisms, l, , l, , l, , l, , l, , l, , l, l, , l, , Animals including human beings are exposed to, various infectious agents like bacteria, viruses, fungi, and parasites. The system of animal body, which, protects it from various infectious agents and cancer,, is known as immune system., The immune system consisting several organs, as, well as white blood cells in the blood and lymph, has the job of fighting off invading pathogens and, preventing the growth and spread of cancers., The lymphoid organs are divided into 3 categories –, primary lymphoid organs, secondary lymphoid, organs and dispersed immune cells., Primary lymphoid organs are bone marrow (in, the hollow centre of bones), the thymus gland, (located behind the breastbone above the heart), and foetal liver which are the major sites of, production of lymphocytes., Bone marrow manufactures the billions of WBC, needed by the body every day. Some newly produce, WBC remain in the bone marrow to mature and, specialize, while others travel to the thymus to, mature., Secondary lymphoid organs, present at or near, possible portals of entry for pathogens, includes, lymph nodes, adenoids tonsils, spleen (located at, the upper left of the abdomen, and groin), Peyer’s, patches (within the intestine), and the appendix., Lymph nodes filter pathogens from the lymph and, expose them to WBC., The spleen filters pathogens from the blood. It is, stocked with WBC that respond to the trapped, pathogens., In addition to the organized lymphoid tissues, there, are other sites, particularly the mucosae, where many, immunocytes are dispersed between other cells, for, example within gut epithelium and lamina propria., , l, l, , l, , l, l, l, , l, , l, , Immunology is the science of development of, immunity against particular pathogen/pathogens., The foundations of science of immunology were, discovered by 3 workers Edward Jenner (1796);, Louis Pasteur (1879); Von Behring (1891)., Immunity may be defined as the body’s ability, to destroy pathogens or other foreign material, and to prevent further cases of certain infectious, diseases. This ability is of vital importance, because the body is exposed to pathogens from, the moment of birth., Immunity was defined by Sir Mac Farlane Burnet., Immunity developed in three ways – by vaccination,, antitoxin and through diseases., The immune system has a series of dual natures,, the most important of which is self/nonself, recognition. The others are: general/specific,, natural/adaptive = innate/acquired, cellmediated/, humoral, active/passive, primary/secondary., Parts of the immune system are antigenspecific, (they recognize and act against particular antigens),, systemic (not confined to the initial infection site,, but work throughout the body), and have memory, (recognize and mount an even stronger attack to, the same antigen the next time)., Self/nonself recognition is achieved by having, every cell display a marker based on the major, histocompatibility complex (MHC). Any cell not, displaying this marker is treated as nonself and, attacked. The process is so effective that undigested, proteins are treated as antigens., , TYPES OF DEFENCE MECHANISM, l, , There are two kinds of defence mechanism against, microbes. These are nonspecific and specific, defence mechanism.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 636, , ŕďőĽę– ĐĽŐńŐĹť, , Non-specific defence mechanism, l, l, , l, , l, , Non specific defence mechanism is also known as, innate or inborn or natural immunity., Innate immunity prevents entry of micro, organisms into tissues or, once they have gained, entry, eliminates them prior to the occurrence of, disease., Innate immunity present from birth are non, specific (acts on many organism) and does not, become more efficient on subsequent exposure to, same organisms., The non specific defence mechanism is further of, two types – external defence (or first line of, defence) and internal defence (or second line of, defence)., , External defence, l, First line of defence comprises physical and, chemical barriers to the entry of pathogens into, the blood., l, Physical barriers are of two kinds – skin and, mucous membrane and chemical barriers includes,, chemicals secreted by skin and mucous membrane, like skin secretion and bacteria, saliva, tears, bile,, gut secretion and bacteria, nasal secretion, cerumen,, vaginal bacteria., l, Mechanically, pathogens are expelled from the, lungs by ciliary action as the tiny hairs move in an, upward motion; coughing and sneezing abruptly, eject both living and nonliving things from the, respiratory system; the flushing action of tears,, saliva and urine also force out pathogens, as does, the sloughing off of skin., l, Saliva, tears, nasal secretions, and perspiration, contain lysozyme, an enzyme that destroys gram, positive bacterial cell walls causing cell lysis., Vaginal secretions are also slightly acidic (after, the onset of menses). Spermine and zinc in semen, destroy some pathogens. Lactoperoxidase is, powerful enzyme found in mother’s milk., l, The stomach is a formidable obstacle in sofar as its, mucosa secrete hydrochloric acid (0.9 < pH 3.0,, very acidic) and proteindigesting enzymes that kill, many pathogens. The stomach can even destroy, drugs and other chemicals., l, An opsonin is a plasma protein binding to, bacteria. This promotes adheshion between the, opsonised bacteria and macrophages because the, , l, , ops on in b in ds to recep tors on ph ag ocyte, membrane, e.g., complement with complement, receptors and phagocytes. Opsonisation and, phagocytosis are more efficient in immune, individuals., A phagocyte is a cell that attracts (by chemotaxis),, adheres to, engulfs, and ingests foreign bodies., , Internal defence, l, When the first line of defence fails to prevent access, of pathogens to the tissues, the body’s second line, of defence come into play., l, The body’s internal defence is carried on by white, blood corpuscles, macrophages, inflammatory, reactions, fever, interferons and complement, system. All the six devices operate together to check, damage to the body by pathogens., l, Macrophages (big eaters) are large phagocytic cells, that arise by enlargement of monocytes., l, Promonocytes are made in the bone marrow, after, which they are released into the blood and called, circulating monocytes, which eventually mature, into macrophages., l, Some macrophages are concentrated in the lungs,, liver (Kupffer cells), lining of the lymph nodes and, spleen, brain, microglia, kidney mesangial cells,, synovial A cells and osteoclasts. They are long lived,, depend on mitochondria for energy, and are best at, attacking dead cells and pathogens of living within, cells., l, Macrophages are of two types fixed and, wandering., l, Fixed macrophages are located in the lining of, blood and lymphatic capillaries in spleen, lymph, nodes, liver and bone marrow., l, The wandering (nonfixed) macrophages occur in, the connective tissue throughout the body. They, move to the site of infection like the leucocytes, and dispose of the microbes. They are called, histiocytes also., l, The macrophages are among the first cells that, respond to the infection., l, Macrophages have many functions –, –, Defence : Wandering macrophages (also called, histiocytes) dispose of microbes in the, connective tissue. Fixed macrophages destroy, microbes in the blood and lymph., –, Giant cell formation : Many macrophages
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▀ŇŇśňĚ– ☼ťřŚĚŇ– ·– ▼ĚěĚňĘĚ– ▐ĚĘĺďňĽřŇř, , Table : Types of Macrophages., Type, Histiocytes, Microglia, Kupffer cells, A l v e o l a r, macrophages, • Sinus lining, macrophages, • Mesanglia cells, • Osteoclast, •, •, •, •, , l, , l, , l, , Location, Connective tissue, Brain, Liver, Lung, Spleen, lymph nodes, thymus, gland, Glomerular of nephrons, Bone, , may fuse to form a large multinucleate giant, cell to capture a foreign body too big for a, single macrophage to engulf., –, Scavenging : Macrophages also dispose of, dead tissue cells and noncellular foreign, matter., –, Antigen display : Macrophages carry the, antigens of the engulfed microbes on their, surface to display them to the lymphocytes in, the lymphatic nodes. This activates the, immune system., –, Secre tion of endogenous pyrog en :, Macrophages secrete interleukin1 (IL1),, also called endogenous pyrogen. It plays a, role in inflammatory response, in causing, fever, and in activation of other phagocytic, cells as well as the T and Bcells to produce, their effect., Inflammatory response is a reaction that causes, redness, heat, swelling, and pain in the area of, infection. Redness and heat are due to capillary, dilation resulting in increased blood flow. Swelling, is caused by the passage of plasma from the blood, stream and into the damaged tissue. The pain is, mainly due to the tissue destruction and to a lesser, extent the swelling., Inflammation is localised to area of infection/tissue, injury by release of substances from micro, organisms or chemicals (chemicals mediators), released from cells in tissues, e.g, histamine from, mast cells. Once organisms destroyed inflammation, settles down., Body temperature in human is controlled by, hypothalamus. The body responds to activating, heat promoting mechanism, eg. shivering and, vasoconstriction untill the new higher temperature, , l, , l, , l, , l, , l, , l, , l, , l, , 637, , is reached. When the thermostat is reset to the, normal level, heat loss mechanism are activated., Body temperature rise causes fever. Fever is often, the result of infection and is caused by release, of chemicals (pyrogens) from damaged tissues, and the cells involved in inflammation. When, enough pyrogens reach the brain, the body’s, thermostat is reset to a higher temperature,, allowing the temperature of the entire body to, rise., Interferons (discovered first by Issacs and, Lindermann) are a heterogenous group of, glycoprotein (Mol wt. 20,00040,000 Dalton), produced by human and other animal cells against, viral infections (or after exposure to other inducers), and which exerts many immunomodulating, functions., Although interferon cannot save an invaded cell,, it works as a warning signal for healthy cells, in, which it interferes with viral replication. These, effects on a virus slow down the progress of, infection and often give the specific defenses of, the immune system time to respond., Interferons are divided into three groups based on, the cell of origin, namely leucocyte (alpha),, fibroblast (beta) and lymphocyte (gamma)., a and b are induced by virus whereas gamma, interferon is induced by antigens and is one of the, effectors of cell immunity., Complement is heat liable i.e. it is inactivated by, heating serum at 56°C for 30 minutes., Immunoglobulins are not inactivated at this, temperature., The complement system can be activated in two, main ways –, –, The first and most potent occurs when IgG (or, IgM) binds to antigen at the surface of a cell., This exposes the Fc region of the antibody such, that the first complement protein (C1) binds., –, The second means of activation is part of, the natural (innate) immune response (i.e.;, neither antibodies or T cell receptors are, involved.) Here certain polysaccharides found, on the surface of bacteria activate the system., This can occur immediately and does not, require prior exposure to the molecules., The complement system plays an essential role in, host defence against infectious agents and in the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 638, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , inflammatory process. It consists of about twenty, plasma proteins that function either as enzymes, or as binding proteins. They are synthesized mainly, in liver., When a pathogen invades the body, a macrophage, brings the foreign antigen to the B cells (plasma, cells). In this way, the B cells “LEARN” about the, antigens on the pathogens surface and START to, make appropriate antibodies. The B cells then, circulate through the body, releasing antibodies that, bind to the new antigen., The complement system triggers a constellation of, effects that helps deal with an infection like, opsonization, chemotaxis, inflammation, lysis, antibody coated cells., , l, , l, , Specific defence mechanism, l, , l, l, , l, , l, l, , l, l, , l, , If a pathogen is able to get pass the body’s, nonspecific defences the immune system reacts with, a series of specific defences that attack the disease, causing agent., Responses of the immune system to specific, pathogens are called specific defences., Specific defence mechanisms is the third line of, defence and developed by an animal in response, to a disease caused by infections of microbes., This third line of defence will recognize, attack,, destroy and remembers each foreign substance and, pathogen that enters the body. It does this by making, specialized cells and antibodies that make the, pathogen useless. For each type of pathogen the, immune system produces cells that are specific for, that particular pathogen., Specific defence mechanism is also called acquired, immunity., Acquired immunity occurs after exposure to an, agent, is specific and is mediated by antibody and, by T lymphocyte namely T cells, cytotoxic T, cells., Acquired immunity is of two types – natural or, active and artificial or passive., Active immunity is resistance induced after contact, with foreign antigens, eg. microorganisms and, activated helper and cytotoxic T lymphocyte. Main, advantage of this immunity is that resistance is, long term and its major disadvantage is its slow, onset especially the primary response., Active immunity is produced by clonal selection, and expansion., , l, , Clonal selection leads to the eventual production, of –, –, A pool of antibodysecreting plasma cells., Plasma cells are Bcells that have booled, up (e.g., forming a large endoplasmic, reticu lum) for mas sive syn thes is a nd, secretion of an antibody. The antibody is, the secreted version of the BCR (Bcell, receptor for antigen)., –, A pool of “memory” cells. These are B, lymphocytes with receptors of the same, specificity as those on the original activated, B cell., Passive immunity is developed to counteract snake, venom, rabies, tetanus toxin and Salmonella, infection., Passive immunity has the advantage of providing, immediate relief having prompt availability of large, amount of antibodies. However, passive immunity, offers some problems: it is not long lasting (short, life span of antibodies); antibodies, being foreign, proteins, may cause reactions; body may produce, its own antibodies to destroy the foreign antibodies,, which may be useful., , IMMUNOGLOBULINS, l, , l, , l, , l, , The globulins, a plasma proteins, plays a major, role in the immunological reactions. These include, reactions involving the antigens and antibodies., Immunoglobulins or specific antibodies or, gamma globulins are blood proteins, which are, found to be defensive only against the specific, microorganisms, or their toxins that evoked that, particular antibody., The antibody molecules may be bound to a cell, membrane or they may remain free. The free, antibodies have three main functions –, –, Agglutination of particulate matter, including, bacteria and viruses, –, Coating of bacteria to facilitate their, subsequent phagocytosis by cells, –, Neutralization of toxins released by bacteria,, e.g., tetanus toxin., Immunoglobulin are glycoproteins, made up of 4, polypeptide chains (linked by disulphide bonds)., There are two long chains, called heavy or H, chains, and two short chains, called light or L, chains. The four polypeptide chains are held
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▀ŇŇśňĚ– ☼ťřŚĚŇ– ·– ▼ĚěĚňĘĚ– ▐ĚĘĺďňĽřŇř, , l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , together to form Yshaped molecule. The top two, tips of this Y shaped molecule bind to the specific, antigens in a lock and key fashion, forming an, antigenantibody complex., Light and heavy chains are subdivided into variables, and constant. The variable portion is used for, binding to antigen and a constant portion, determines its adherence and diffusivity (i.e. for, various biological functions), e.g. complement, activation and binding to cell surface receptors., Constant regions of heavy chains define five, classes of Igs, some with subclasses and two, identical light chains belongs to one of 2 types—, Kappa (k) and l (lambda)., Types of immunoglobulins are – IgG, IgM, IgA, (IgA 1 and 2), IgD and IgE (IgE 1, 2, 3, and 4)., IgG, the most abundant immunoglobulin, is, found in blood, lymph and intestine, protects, the body against bacteria, fungi and viruses by, activating complement system, enhancing, phagocytosis (opsonizes) and neutralising, toxins., It is the only isotype that can pass through, placenta, protects against blood cell antigens as, well as provide passive immunity to new born., It is the predominant antibody in secondary, response., IgA is the second most abundants, immunoglobulin in human serum and is the, primary immunoglobulin of exocrine secretions., It is available in colostrum and mother’s milk, the, immunoglobin is abundant in all secretions of the, body including saliva and tears. It is also common, in mucous membranes of throat, bronchi, nose,, intestine, etc. It is effective against a number of, antigens, providing local immunity., In milk these antibodies are thought to provide, immune protection to nursing infants, whose own, immune systems are not yet fully developed., IgM (macroimmunoglobulin) is the largest of, the immunoglobulins and the first to reach the, site of infection being present in circulating fluids., It increases IgG production and complement, fixation. The immunoglobulin is involved in ABO, incompatibility., IgM is the antibody made in greatest amounts by, the foetus. It can be produced by the foetus in, certain infections. Because it is a large molecule,, , l, , l, , l, , l, l, , l, l, l, l, , l, , l, , 639, , it cannot diffuse well, and is found in the, interstitium only in very low quantities., Due to its polymeric nature, IgM possesses high, avidity, and is particularly effective at complement, activation. It is also a socalled “natural antibody”., It is found in the serum without any evidence of, prior contact with antigen., IgD is present in small quantity in serum tissue, where it functions as a receptor for various toxins, and allergens. While lgD’s functions is not yet, completely understood, it is often coexpressed with, lgM and is used as a marker, naive B cells. It may, also be involved in the differentiation of B cells, into plasma and memory cells., IgE is a monomeric immunoglobulin with the, heavy chain. It is involved in immediate allergic, reactions triggering the release of histamine, and other inflammatory chemicals. It is, concentra ted in lungs, s kin a nd mucou s, membrane. Excess secretion causes asthma. It is, the main host defence against helminthes, infections. They donot activate complement., Only IgE is heat labile., The antibody molecule is the basic functional, unit of the immune response., Antigen is a substance that when introduced into, a vertebrate host provokes an immune response, leading to acquired immunity. It stimulates the, immune system to produce protective chemicals, or special cells to destroy the antigens., The protective chemicals are called antibodies., The ability of the antigen to stimulate antibody, formation is called antigenicity., Antigens of proteinaceous nature are known as, complete antigens., Some antigens consisting of lipids and, carbohydrates cannot produce antibodies on their, own, are known as haptens. Haptens stimulate, antibody formation by binding with proteins., Antigen and antibody have complementary reactive, sites that fit together like lockandkey. Antibodies, react with antigens and make them inactive or, harmless., Interaction between antigen and antibody involve, noncovalent binding of an antigenic determinant, (epitope) to the variable region (complementary, determining region CDR) of both heavy and light, immunoglobulin chains.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 640, , ŕďőĽę– ĐĽŐńŐĹť, , Polyclonal or Monoclonal antibodies, Antibodies that arise in an animal in response to, typical antigens are heterogeneous, because they, are formed by several different clones of plasma, cells; i.e, they are polyclonal. Antibodies that arise, from a single clone of cells, e.g, in a plasma cell, tumor (myeloma), are homogeneous; i.e., they are, monoclonal. Monoclonal antibodies also can be, made in the laboratory by fusing a myeloma cell, with an antibodyproducing cell. Such hybridomas, produce virtually unlimited quantities of, monoclonal antibodies that are useful in diagnostic, tests and in research. Hence hybridoma are hybrid, cell culture formed of antigen sensitised cells, fused, with myeloma cancerous bone marrow cells for, indefinite production of monoclonal bodies., Monoclonal antibodies are also used in, immunoassay. They are used to detect the, hormones present in urine (pregnancy test kits), in, detecting drugs in urine (for athletes) and in, detecting HIV virus., , l, , l, l, , l, , l, , IMMUNE RESPONSE, l, , The immune response can be defined as a particular, reactions induced in a host by an antigenic stimulation., , l, , Immune responsive cells can be divided into five, groups based on (i) the presence of specific surface, components and (ii) function: Bcells (B, lymphocytes), Tcells (T lymphocytes), Accessory, cells (Macrophages and other antigenpresenting, cells), Killer cells (NK and K cells), and Mast cells., Immune response may be primary or secondary., The reaction of the body’s immune system to the, first attack of microbes (antigens) is called primary, immune response., During a primary response, the antigens eventually, disappear from the blood, having been destroyed, by antibodies and killer Tcells or macrophages., This takes about a week (510 days) after the, microbial attack. During this period, B cells divide, and mature into plasma cells that produce enough, antibodies to destroy the antigens. It takes about a, week or so for the influenza symptoms to disappear., Recovery from an infection shows that the body’s, immune system is working., The reaction of the body’s immune system to any, subsequent infection of the same microbe is termed, secondary immune response., This response is quicker and more intense than, the primary immune response. This is so because, , Table : Functions of the immune cells, Immune cells, , Functions, , Features, Lymphoid lineage cells, , (A) Lymphocytes, , –, –, , Main constituents of the lymphoid tissues, Functionally two types – T lymphocyte, and B lymphocytes, , – Secrete lymphokines to activate T C , T S and, B cell response., – Activate macrophage system., , (i) Tlymphocytes, Subsets of, Tlymphocytes, are, – T helper, , –, , – TH cells act as memory cells., , – T suppressor, , –, , Get mature in the thymus gland in the, presence of thymic hormones, Mainly responsible for cell mediated, immunity, Functionally heterogenous, Classified into regulator cells and, effector cells, Develop and mature in bone marrow of, adult, Functional Bcells are called plasma cells, Plasma cells produces respective antibodies, , –, – T cytotoxic, – T delayed type –, (ii) Blymphocytes, , –, –, –, , – Suppressor T cells offers immune tolerance, – TC cells destroy cancer cells, – TD cells are involved in hypersensitivity, – Specific antibodies for antigen is produced, – Exhibit characteristic antigen – antibody, reactions, contd ...
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 641, , ▀ŇŇśňĚ– ☼ťřŚĚŇ– ·– ▼ĚěĚňĘĚ– ▐ĚĘĺďňĽřŇř, , Immune cells, , (B) Null cells, , (i) Natural killer, (NK) cells, (ii) Killer (K) cells, , Features, –, –, –, –, , Cytoplasm bear large granules, Cell surface lacks immunoglobulins, Kidney shaped nucleus, Two types – NK and K cells, , –, –, , Nonphagocytic cells, Do not require antigenic stimulation, , –, –, –, , Nonphagocytic cells, Requires antibody mediation, Requires participation of complement, system., , Functions, , – Kill tumor cells, – Defend viral infections, – Kill tumor cells, viruses, bacteria, fungi and, parasites., , Myeloid lineage cells, (A) Monocytes, , (B) Polymorpho, nuclear cells, (PMN), , (C) Accessory cells, , (i) Mast cells, , –, –, –, –, , Circulating phagocytic cells, Large, motile, amoeboid cells, Phagocytes of blood, These get differentiated into macrophages, when migrate to body tissues, , – Responsible for lytic activity, – Remove dead cells, debris and pathogens by, microbiocidal activity, , –, –, –, –, , Contains multilobed nucleus, Cytoplasm contain rich granules, Exhibit staining property, Three different kind of PMN are, neutrophils, basophils and eosinophils, , – Destroy bacteria and viruses, – Eosinophils provide immunity to helminthes, parasites, – Basophils participates in allergic reactions, , –, , Additional cells present throughout the, body for assisting the immune response., They are of three types mast cells,, Antigen presenting cells, Platelets, , –, , – Mediators of hypersensitivity, – They are modified basophils, – Mediate the inflammatory reactions., – Present throughout the body tissue, – Secretes serotonin, histamine, heparin etc. – Immunity against parasites., , (ii) Antigen, presenting, cells (APC), , – Process the antigens, – These are nonlymphocytic cells, – Involved in the presentation of antigens – Help in recognition of antigen, – Some of the cells involved in the antigen – Assist the immunocompetent cells., presentation are – follicular dendritic cells,, interdigitating dendritic cells and, Langerhan’s cells, , (iii) Platelets, , – They are nonnucleated cells, – Spherical and colourless derived from, megakaryocytes, – They secrete histamine and serotonin, , – Have role in blood clotting, – Involved in inflammation, – Contribute to immediate hypersensitivity, reactions
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 642, , l, , ŕďőĽę– ĐĽŐńŐĹť, , the memory B cells are present to quickly deal with, the invading microbes by forming antibodies. Body, “remembers” that it has previously encountered this, type of infection., Primary and secondary humoral response are of, two types of humoral immune response., , CELLULAR BASIS OF IMMUNE SYSTEM, l, l, , l, , l, , l, , l, , Lymphocytes (a type of WBCs) are the main cells, of immune system of the body., Lymphocytes, meant for immune system, are of, two types: Tcells and Bcells. Both types of cells, develop from the stem cells found in the liver and, yolk sac of the foetus and in the bone marrow cells, during adult life., Those lymphocytes that migrate to the thymus and, differentiate under its influence are called ‘Tcells’,, while those cells that continue to be in the bone, marrow for differentiation are known as ‘Bcells’., The thymus and bone marrow (or the bursa in birds), are the primary lymphoid organs. The final, maturation of young lymphocytes occur in, secondary lymphoid tissues like lymph nodes,, spleen and tonsils., Blymphocytes are independent of the thymus, and in man probably complete their early, maturation within the bone marrow., Tcells are responsible for cellular immunity,, however, Bcells produce the antibodies—about, 20 trillions per day that take part in the humoral, immunity., The Blymphocytes and Tlymphocytes form, humoral (or antibody mediated) immune system, (AMIS) and cellmediated immune system, (CMIS) respectively. Both the immune systems, need antigens to come into action, but they respond, in different ways., , Humoral immune system, l, , l, , Antibodymediated (or humoral) immunity is, associated with the appearance of antibodies,, secreted by cells of the Blymphocyte series, in the, extracellular fluids such as plasma, lymph and, external secretions., The AMIR defends the body against (a) some, viruses, (b) bacteria with polysaccharide capsules, and (c) toxins that enter the body fluids (blood and, lymph)., , l, , l, l, , l, , l, , l, , When antibodies on a B cell’s surface bind antigens,, the B cell is activated and divides, producing a, clone of daughter B cells. The daughter cells, specialise into plasma B cells and memory B cells., Plasma B cells (also known as effector cells) are, antibody factories., Plasma cells are highly specialized cells that, produce defensive proteins and secrete them into, the blood., The plasma cells do not migrate to the site of, infection and act through a fluid (lymph). Hence,, they are said to form humoral immune system (L., humor = liquid). The Blymphocytes are short, lived and are replaced every few days from the, bone marrow., Memory B cells live for a long time and serve to, quickly dispose of the antigens in case reinfection, of the same virus or bacterium occurs., The antibodies fight the antigens in five different, ways –, –, Neutralization. Some antibodies neutralize, the antigens, termed toxins (viral toxins,, bacterial toxins, snake venom), and make them, ineffective. They are called antitoxins. The, phagocytes dispose of the neutralized antigen, antibody complexes., –, Agglutination. Certain antibodies cause the, particulate antigens (bacteria, red corpuscles), stick together in clumps, thus immobilizing, them for easy disposal by the phagocytes, through ingestion. They are termed, agglutinins., –, Precipitation. Other antibodies combine with, the antigens to form precipitates that are easily, ingested by the phagocytes. They are known, as precipitins., –, Opsonization. Some antibodies coat the, surface of the microbes and make them more, susceptible to phagocytosis. Such antibodies, are known as opsonins., –, Complement activation. Antibodyantigen, complexes activate complement proteins, which may –, –, Lyse cells walls of bacteria, causing their, disintegration, –, Incite inflammatory response, –, Opsonize antigens, –, Attract phagocytes to areas of infection.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▀ŇŇśňĚ– ☼ťřŚĚŇ– ·– ▼ĚěĚňĘĚ– ▐ĚĘĺďňĽřŇř, , Cell mediated immune system, l, , l, , l, , l, , l, , l, , l, l, , l, l, , l, , l, , Cellmediated immunity is mediated by cells of, the Tlymphocyte series with antigenspecific, receptors on their surfaces., The CMIR defends the body against viruses, fungi, and some bacteria which have entered the host’s, cells., On stimulation by contact with antigens, the T, lymphocytes produce by division a clone of Tcells,, the lymphoblasts. There are separate Tcells for each, type of antigen that invades the body. The Tcells, leave the lymphoid tissue and migrate to the site of, infection. The Tcells have a lifespan of 4 to 5 years, or even longer. The Tcells comprising the clone are, committed Tcells having specific functions., Tcell perform several important function which, can be divided into 2 categories – regulatory and, effector., The regulatory functions are mediated by helper, (CD 4 positive) Tcells which produces interleukins, and the effector functions are carried out, primarily by cytotoxic (CD 8 positive) Tcells, which kill virus infected cells, tumor cells and, allografts., They are similar morphologically but of 4 types, functionally killer or cytotoxic cells, helper, Tcells, suppressor T cells and memory Tcells., Cytotoxic T cell are WBCs that attack and destroy, foreign and dangerous cells (cancer)., Cytotoxic Tcells attach to foreign, antigenbearing, cells, such as bacteria cells, and interact directly, i.e., by celltocell contact. This type of response, is called cellmediated immunity., Cytotoxic or killer T cells (CD8+) do their work by, releasing lymphotoxins, which cause cell lysis., Helper T cells (CD4+) serve as managers, directing, the immune response. They secrete chemicals called, lymphokines that stimulate cytotoxic T cells and B, cells to grow and divide, attract neutrophils, and, enhance the ability of macrophages to engulf and, destroy microbes., Lymphokines are chemical factors produced by, lymphocytes for regulating activity of various cells, of immune system. They include interleukins,, granulocyte monocyte colony stimulating factor,, interferong., Suppressor T cells inhibit the production of, cytotoxic T cells once they are unneeded, lest they, cause more damage than necessary., , l, , l, , 643, , Suppressor T cells help to shut down the immune, response after the pathogen has been cleared from, the body., Memory T cells are programmed to recognize and, respond to a pathogen once it has invaded and been, repelled., Ø, , Ø, , Ø, , Ø, , Cytokines are soluble, nonantibody proteins, released by cells of the immune system, e.g.,, interleukin1 produced by macrophages,, perforin secreted by killer Tcells., Antiseptic is an agent that prevents the, growth of microorganisms by killing them., Examples : spirit, dettol., The principle that the phylogenies of parasites, and their hosts generally evolve in parallel, are known as Fahrenholz’s Rule., Herd immunity is the indirect protection, from infection of susceptible members of a, population and the protection of the, population as a whole, which is brought about, by the presence of immune individuals., , DISORDERS OF IMMUNE SYSTEM, l, , l, , l, l, , l, l, , An improper function of the immune system gives, rise to the following groups of disorders :, hypersensitivity (allergy), auto immune, diseases, and immunodeficiency., Hypersensitivity is the excessive immune response, to common antigens. These antigens are present, on/in certain substances called allergens (e.g., dust,, pollen, moulds, certain foods, some medicines)., Allergy involves mainly IgE antibodies and, histamine., Asthma is a common manifestation of allergy., Sometimes a sudden violent and fatal reaction may, occur in sensitive individual due to an allergen. It, is called anaphylaxis., Antihistamine is a medicine that gives relief from, allergy, eg avil., Types of hypersensitive reactions are –, –, Type I reactions (i.e, immediate, hypersensitivity reactions) involve, immunoglobulin E (IgE)–mediated release of, histamine and other mediators from mast cells, and basophils., –, Type II reactions (i.e, cytotoxic, hypersensitivity reactions) involve, immunoglobulin G (IgG) or immunoglobulin
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 644, , l, , l, , l, , l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , M (IgM) antibodies bound to cell surface, antigens, with subsequent complement, fixation., –, Type III reactions (i.e, immunecomplex, reactions) involve circulating antigen, antibody immune complexes that deposit in, postcapillary venules, with subsequent, complement fixation., –, Type IV reactions (ie, delayed, hypersensitivity reactions, cellmediated, immunity) are mediated by T cells rather than, by antibodies. One type of Type IV reaction, involves patients who have become sensitized, to tuberculin, found in Mycobacterium, tuberculosis, the causative agent of, tuberculosis., Autoimmune diseases result when the immune, system attacks and destroys selfcells and, molecules, e.g., multiple sclerosis (caused by the, attack of antibodies on the myelin sheath of nerve, cells), insulin dependent diabetes, rheumatoid, arthritis, etc., Many autoimmune diseases are found more, commonly in old age, for example rheumatoid, arthritis and a number of autoimmune thyroidithis, conditions (e.g., Hashimoto’s disease)., Immunodeficiency diseases are caused due to a, defect in one or more components of the innate or, adaptive immunity., Immuno deficiency may result from gene, mutations, e.g., severe combined immunodeficiency, (SCID); infections, e.g. AIDS caused by HIV, and, malnutrition or accidents., SCID, due to defective gene for adenosine, deaminase, is a congenital disorder in which both, the B and T lymphocyte are absent and due to, which patient dies of even minor infection., SCID is the first genetic disorder to be combated, with gene therapy., AIDS is caused by the infection from a retrovirus, known as human immunodeficiency virus (HIV)., The virus has a single stranded RNA genome, which, reverse, transcribed and incorporated into the host, genome. HIV specifically attacks Thelper cells, of the immune system., [For more details on AIDS refer chapter Common, Human Diseases], Western blot test confirm the elisa test in AIDS,, through the detection of HIV proteins., , l, , l, , l, , l, , The Russian Biologist, Ivanowsky (1892) was the, first to demonstrate the presence of viruses in, tobacco leaves suffering from mosaic disease., Infact, the first virus was discovered by Ivanowsky., W.M. Stanley (1935) an American microbiologist, and Nobel Prize Winner (1946) isolated Tobacco, Mosaic Virus (TMV) from infected leaf., Arthur Ashe, a ground breaking Black tennis player, died of AIDS. He was infected by a blood, transfusion during his heart bypass surgery, probably, in 1983., Lentivirus is a slow acting virus, eg. HIV., , IMMUNISATION, l, , l, , l, l, , l, l, , l, , l, , l, l, , l, , Immunisation is the phenomenon of specific, antibody production in an individual against the, potential attack of a pathogen. It is carried out, through vaccination (active) and inoculation of, antiserum (passive)., The aim of vaccine is to provide effective immunity, by establishing adequate levels of antibody and a, population of memory lymphocytes which can, expand rapidly on renewed contact with antigen., Live attenuated vaccine are more potent (active), than killed vaccine., Vaccination is the process of introduction of a, preparation of antigenic proteins of pathogens or, inactivated weakened pathogens (vaccine) into the, human body., Vaccination has its origin from the works of Edward, Jenner and Louis Pasteur., Edward Jenner was able to develop resistance to, small pox in a boy by introducing the fluid from, sore of a milkmaid who was suffering from cowpox., Louis Pasteur observed that, cholera bacteria from, ageing cultures, when injected into chickens, they, became immune to fowl cholera. Using this method, Pasteur developed vaccine against rabies in 1885., A vaccine consist of a preparation of antigenic, proteins of the pathogen or weakened/inactivated, pathogen itself., Toxinosis is a disease or lesion caused by the action, of a toxin., Serology is the study of serum, especially of specific, immune or lytic serums (L. serum = whey, G. logos, = study)., Antitoxins are agents which can neutralise the, toxins produced by pathogens and the ones present, in venoms.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▀ŇŇśňĚ– ☼ťřŚĚŇ– ·– ▼ĚěĚňĘĚ– ▐ĚĘĺďňĽřŇř–, l, , l, , l, , l, , l, l, , l, , Passive immunisation may be induced by –, administration of an antibody containing, preparation, transfer of maternal antibodies across, the placenta; and by transfer of lymphocyte to, induce passive cellular immunity., The antigenic protein may be prepared from the, pathogen, or produced in a transgenic organism, eg., hepatitis B vaccine is produced from transgenic yeast., A proper matching of proteins (called human, leucocyte antigens or HLA) is essential for a, successful organ transplant or skin graft., A transplant should be given preference as under., Identical twins > Sibling > Parent > Unrelated, donor., Passive immunization can be natural or artificial., Natural passive immunization includes the passage, of maternal IgG across the mammalian placenta. In, regions with a high incidence of tetanus, immunization, of pregnant women with tetanus toxoid results in them, making antitetanus IgG which is transmitted across, the placenta to the foetus, and can protect the newborn, from tetanus. In humans, IgA is transmitted to the, baby’s gut via colostrum and milk., Artificial passive immunization is effected when, immunodeficient patients are given doses of, antibodies from a donor; travelers to the tropics, may be given ‘pooled gglobulins’ (antibodies) from, donors who live in the visited areas; hopefully, the, cocktail of donated antibodies may protect them, from endemic diseases., , ORGAN TRANSPLANT, l, , l, , l, , l, , Transplantation involves the removal of damaged/, injured tissues or organs from the body of a person, and their substitution by similar tissues/organs from, a donor., In autografts one’s own tissue is grafted to another, part of the body, e.g. skingrafts for burn treatment, or plastic surgery. The most successful, transplantation is the autograft., In isografts the donor and recipient are genetically, identical, e.g., transplantation from a twin, brother or sister., Allografts is the transplantation between, individuals of same species, but with different, genetical background. The success of this transplant, is moderate; it is generally used as temporary, , l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , 645, , measure until the damaged tissue is able to repair, itself., Xenograft transplant occurs between animals of, different species. This type of transplantation is, used primarily as a physiological dressing over, serious burn injuries., Transplantation may result in the rejection of, transplanted organs. The immune system, recognizes the protein in the transplanted tissue or, organs as foreign and initiates cellular immunity., Grafts will not be rejected if the graft is not, vascularized, the host and donor have the same, genotype and so have the same MHC genes (e.g.,, identical twins or members of inbred strains of, mice), etc., To suppress the immune response during, transplantation, histocompatibility antigen and, immunosuppresants play an important role., Histocompatibility is the property of having the, same, or mostly the same, alleles of a set of genes, called the major histocompatibility complex., The Major Histocompatibility Complex (MHC), is a set of molecules displayed on cell surfaces that, are responsible for lymphocyte recognition and, “antigen presentation”., The major histocompatibility complex is encoded, by several genes located on human chromosome 6., Major histocompatibility complex (MHC) also, referred to in humans as the HLA (or Human, Leucocyte Antigen) system., These genes are expressed in most tissues as, antigens, to which the immune system makes, antibodies. The immune system at first makes, antibodies to all sorts of antigens, including those, it has never been exposed to, but stops making, them to antigens present in the body., Immunosuppressive, drugs, or, immunosuppressants are drugs, that are used in, the immunosuppressive therapy to inhibit or, prevent activity of the immune system., Clinically immunosuppressants are used to prevent, the rejection of transplanted organs and tissues (e.g., bone marrow, heart, kidney, liver), treatment of, autoimmune diseases or diseases that are most likely, of autoimmune origin (e.g. rheumatoid arthritis,, Myasthenia gravis, systemic lupus erythematosus,, ulcerative colitis).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 646, , ŕďőĽę– ĐĽŐńŐĹť, , Chapter 72, , Common Human Diseases, l, , l, , Any condition which interferes with the normal, structure & function of human body that is, manifested by a characteristics sets of symptoms &, sign whose etiology, pathology & prognosis may, be known or unknown is called disease., Terms related to diseases are –, –, Infection : It refers to the entry and, development or multiplication of viruses and, organisms in the body of larger organisms. It, implies body’s response to defend itself in, some way against the invaders. A disease, resulting from an infection is called infectious, disease. Factors influencing infection are –, number of invading pathogens, virulence, of pathogens, resistance of the body of, disease and immunity., –, Contamination : It refers to the presence of, diseasecausing agents in nonliving materials,, such as water, milk, and food, used by the, host, without any response to the pathogens., –, Infestation : It refers to the lodgement,, development and reproduction of parasites,, generally arthropods, on the surface of the, body, or in the clothing, e.g., louse infestation., –, Incubation period – It is the time elapsed, between exposure to a pathogenic organism, and when symptoms and signs are first, apparent., –, Etiology : Etiology (alternately aetiology,, aitiology) is the study of causation. It is the, study of all factors that may be involved in, the development of a disease, including the, patient’s susceptibility, the nature of the, disease causing agent, and the way in which, the person’s body is invaded by the agent., –, Epidemiology : It is the study of the, distribution and determinants of disease in, , l, l, l, , l, l, , human populations, and the application of this, study to control of health problems., –, Prophylaxis : It refers to any medical or public, health procedure whose purpose is to prevent,, rather than treat or cure, disease. Roughly,, prophylactic measures are divided between, primary prophylaxis (to prevent the, development of a disease) and secondary, prophylaxis (where the disease has already, developed and the patient is protected against, worsening of this process)., –, Reservoir of infection for pathogens : Every, pathogen has some reservoir where it normally, lives when it is outside the host susceptible to, the disease. The reservoir varies for different, pathogens. It may be soil, water, animals, air, and other persons called carriers. The animals, which act as reservoirs do not contract the, diseases and are known as reservoir hosts., On the basis of their occurrence diseases are of, two types – congenital and acquired disease., Congenital diseases are inborn disease present, from the birth., These diseases are generally inheritable, caused, by ge ne or chromosoma l muta tion, eg ., haemophilia, Down's syndrome, alkaptonuria etc., (For congenital diseases refer chapter Human, Genetics & its Disorders)., Acquired disease occur only after birth & are, noninheritable., Two types of acquired diseases are – communicable, disease & noncommunicable disease., , COMMUNICABLE DISEASES, l, , Communicable diseases are infectious diseases, and caused by pathogens which spread from, infected persons to healthy persons.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 647, , ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř–, l, l, , l, , l, , l, l, , Communicable diseases are of two types –, contagious and noncontagious disease., Contagious diseases are transmitted from infected, persons to healthy person through simple contact., Eg. syphilis, chickenpox, measles, leprosy etc., Noncontagious diseases are transmitted from, infected to healthy one through an agency of, water, food or air (eg. ascariasis, cholera, typhoid), or by microorganisms infected inside the human, body by some carrier or vector host (eg. measles,, filariasis, plague etc)., Depending upon the causative agent, communicable diseases are of following types –, viral, bacterial, protozoan, helminthic,, mycoplasmal, rickettsial, chlamydial etc., Disease caused by mycoplasma are bronchitis,, acute leukaemia etc., Fungi causes ringworm, thrush, Tinea,, pulmonary aspergillosis & athelete's foot diseases, etc., , Viral diseases, l, l, , Viral diseases are transmitted by direct contact,, fomite & droplet method., Types of viral diseases are – influenza/flu, small, pox, chicken pox, measles, mumps, poliomyelitis,, rabies, hepatitis & dengue., , Influenza, l, Influenza (also called flu) is an acute respiratory, tract infection caused by influenza virus., l, Influenza virus, Myxovirus influenzae is a ribovirus, (RNA virus) with fragmented genome., l, Influenza is characterized with bronchitis,, coughing, sneezing, ear infection & pneumonia etc., through inflammation of respiratory tract & eyes., l, Incubation period of influenza virus is 23 days., l, Influenza is epidemic, endemic & pandemic., l, Endemic influenza is caused by Haemophilus, infleunzae, a gram (–) ve bacterium., l, Asian flu is viral influenza., l, Influenza virus has 3 forms – A, B, & C. Vaccine, is available against influenza virus A., Small pox, l, Small pox is highly contagious disease., l, Causative agent for small pox is DNA virus,, Variola virus., l, Incubation period is 12 days in case of small pox., , l, , l, l, l, , Small pox is characterised by high fever, headache,, appearance of rashes followed by papules, vesicles,, pustules & finally scabs., Permanent pox marks left on skin lead to blindness, also., First vaccination against small pox was developed, by Edward Jenner in 1796., Small pox has been eradicated globally., , Chicken pox, l, Chicken pox is caused by DNA virus, Varicella zoster with 1416 days of incubation period., l, It is more common & less severe in children &, severe but rare in adults., l, Scabs in chicken pox falls off without leaving, any mark., l, Boric acid, calamine and benzyl benzoate reduces, itching and tendency to scratch., l, Passive immunity in chicken pox is possible through, Zoster immunoglobulins (ZIG)., Measles, l, Measles is highly infectious eruptive viral disease., l, It is caused by RNA containing Rubella virus/, Polynosa morbillorum., l, Measles is also transmitted to developing foetus, through placenta., l, Measles is accompanied by coughing, sneezing,, skin eruptions of small red spots (rubeola),, conjunctivitis etc. with incubation period of 10, 14 days., l, Antibiotics & sulpha drugs are effective in, measles., l, German measles is caused by Rubella virus., l, It is known to cause congenital problems resulting, in eye defects, deafness & cardiac problem., Kyasanur forest disease, Kyasanur forest disease (KFD) is a viral, haemorrhagic fever caused by infection with a, flavivirus from small wild animals. KFD was first, recognised in 1957 during a fatal epizootic of wild, monkeys in Mysore (Karnataka), India. Forest, workers are particularly at risk, and mortality may, reach 10%. The causative virus is a tickborne, virus belonging to the genus Flavivirus of the, family Flaviviridae, which has been isolated from, ticks, monkeys, and humans. The principal vector, appears to be the tick Haemaphysalis spinigera,, whereas the vertebrate reservoir is uncertain.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 648, , ŕďőĽę– ĐĽŐńŐĹť, , Mumps, l, Mumps is caused by RNA containing Paramyxo/, mumps virus., l, It spreads through droplet infection or direct, contact with the mucus membranes of mouth., l, It is characterised by swollen parotid gland (hence, infectious parotitis) due to which patient has, difficulty in swallowing & opening of mouth., l, Secondary infections may also cause sterility/, infertility when it involves male & female gonads., l, Incubation period is 1226 days., l, MMR vaccine is used against mumps, measles, & rubella., Poliomyelitis, l, Poliomyelitis is highly infectious disease of infants, & children., l, Causative agent of poliomyelitis is a small RNA, containing Polio virus or enterovirus., l, Poliovirus multiplies in alimentary canal then passes, to lymph, blood & finally to CNS in dorsal horn, cells of spinal cord & brain stem resulting in paralysis, in children. Hence also called infantile paralysis., l, Vaccine for polio are killed Salk's vaccine & live, Sabin's oral vaccine., Rabies, l, Rabies or hydrophobia is caused by RNA virus,, Rabies virus (Lassa virus)., l, Rabies is 100% fatal disease and affects all warm, blooded animals and is exclusively transmitted, by the bites of carnivores., l, It is transmitted to human beings by biting/saliva, of rabid dog, monkey, cats etc., l, It leads to encephalitis, fear of water, (hydrophobia), high fever, severe headache, spasm, of throat & chest leading to death., l, Characteristic cytoplasmic inclusions called Negri, bodies found in many neurons helps in rapid, diagnosis., l, Rabies virus is neurotrophic i.e., damage motor, neurons of brains., l, Vaccine against rabies was developed by, Louis Pasteur., Hepatitis, l, Hepatitis is a gastroenterological disease featuring, inflammation of liver., l, It is caused by the infecton with one of the five, viruses called hepatitis A, B, C, D and E., , l, , l, , l, , l, l, l, , l, , l, l, , l, l, , l, , l, , l, l, , l, , Hepatitis B virus (HBV) is the most serious type, of viral hepatitis and the only one causing chronic, hepatitis for which vaccine is available., In addition to the hepatitis viruses, some other, viruses can cause hepatitis including cyto, megalovirus, EpsteinBarr virus, yellow fever virus,, Rubella virus etc., Hepatitis A virus (also called catarrhal jaundice), causes hepatic anorexia resulting in liver damage, or jaundice., Its mode of transmission is by faccaloral route., It is formerly called infectious hepatitis or, epidemic hepatitis., Hepatitis B, popularly called serum hepatitis or, transfusion hepatitis, is caused by hepatitis B, virus. It also called Dane particle., Identified methods of transmission of hepatitis B, includes blood (blood transfusion, now rare),, tattoos (both amateur and professionally done),, horizontally (sexually or through contact with, blood and bodily fluids) or vertically (from mother, to her unborn child)., Hepatitis B virus is spherical and double shelled., Genetic material is circular ds DNA., Hepatitis C (originally non A nonB hepatitis) can, be transmitted through contact with blood, (including through sexual contact)., The HCV (hepatitis C virus) has single stranded, positive RNA., Hepatitis D (Delta hepatitis) is caused by, simultaneous infection of HBV and delta virus, HDV., Delta virus has single stranded small circular minus, sense RNA. The genome can encode only for its, nucleoprotein but not the capsid., Hepatitis D virus cannot proliferate without the, presence of hepatitis B virus, because its genome, lacks certain genes., Symptoms are similar to those of hepatitis B but, are more severe and cause large scale damage., Hepatitis E is enterically transmitted non A, non, B hepatitis (HNANB). The virus is naked (non, enveloped) and spherical with a diameter of 2728, nm. It possesses a single positive stranded RNA., Hepatitis E was first recorded in 1955 in Delhi, when some 29000 cases were identified. Like, hepatitis A, hepatitis E spread through faecal, contaminated water and food.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř–, l, l, , l, , l, , l, , l, , l, l, , Incubation period is 56 weeks (28 weeks)., Symptoms are similar to those of hepatitis A but, bilirubin levels are usually higher. Jaundice is, deeper and prolonged., Personal cleanliness, boiled water, properly heated,, cooked and clean food articles and control of files, are required in period of epidemic. Vaccine is, available., Ethanol, mostly in alcoholic beverages, is an, important cause of hepatitis. Usually alcoholic, hepatitis comes after a period of increased alcohol, consumption., Alcoholic hepatitis is characterized by a variable, constellation of symptoms, which may include, feeling unwell, enlargement of the liver,, development of fluid in the abdomen ascites, and, modest elevation of liver blood tests., Alcoholic hepatitis can vary from mild with only, liver test elevation to severe liver inflammation, with development of jaundice, prolonged, prothrombin time, and liver failure. Severe cases, are characterized by either obtundation (dulled, consciousness) or the combination of elevation, bilirubin levels and prolonged prothrombin time;, the mortality rate in both categories is 50% within, 30 days of onset., Alcoholic hepatitis is distinct from cirrhosis, caused by long term alcohol consumption., Alcoholic hepatitis can occur in patients with, chronic alcoholic liver disease and alcoholic, cirrhosis. Alcoholic hepatitis by itself does not lead, to cirrhosis, but cirrhosis is more common in, patients with long term alcohol consumption., , Yellow fever, l, Yellow fever caused by an arbovirus is a, haemorrhagic disease transmitted by the infected, Aedes aegypti., l, Symptoms of yellow fever are headache, fever,, vomiting, rupture of veins in kidneys, spleen, liver,, etc. In severe cases, the skin of the sufferer becomes, yellow from jaundice, hence the name yellow fever., l, Max Theilder in 1951 got Nobel Prize for the, development of vaccine for yellow fever., Dengue, l, Dengue fever is caused by a RNA containing arbo, virus (arthropod born virus) of flavi virus group, which also causes yellow fever., , 649, , Dengue is caused by viruses DEN1, DEN2, DEN, 3, DEN4., l, Dengue virus is spread by a day time biting of, female tiger mosquito or Aedes aegypti., l, Aedes aegypti is primarily a daytime feeder and, mainly bites in the morning or late in the afternoon, in covered areas., l, Two types of dengue fever are – classical dengue, fever & dengue haemorrhagic fever., l, Classical dengue fever (break bone fever) is more, severe in adults & characterised bymild conjunctivitis,, high fever, backache, retro – orbital pain etc., l, Dengue haemorrhagic fever is a fatal form with, nausea, headache, vomiting, abdominal pain etc., AIDS, l, AIDS (Acquired Immunodeficiency Syndrome), sometimes called slim disease., l, AIDS is a chronic life threatening disorder which, damages the human body’s immune system., l, AIDS is caused by HIV (Human Immunodeficiency, virus) which belongs to retrovirus (group of RNA, virus)., l, There are two types of HIV namely HIV 1 and, HIV 2, the most common virus currently associated, with AIDS is HIV1., l, The HIV virus can only survive in body fluids like, blood, semen, vaginal secretion etc., l, HIV is transmitted through body fluids by –, –, Sexual contact with an HIV infected partner, (it account for 75% of infection)., –, Infected blood, –, Shared needles, syringes, shaving razors, contaminated with infected blood, –, Mother to child (during child birth or breast, feeding), –, In rare cases the virus may be transmitted, through organ or tissue transplants, artificial, insemination through donated semen, or un, sterilized dental or surgical equipment., l, HIV is not transmitted through – ordinary, contact (hugging, dancing, sneezing, talking,, touching, or shaking hands) with someone who, has HIV or AIDS; sweat, tears or saliva, or, through sharing food, utensils, towels, bedding,, a swimming pool, telephone or toilet seat with, someone who has AIDS; bedbugs or mosquitoes., l, HIV virus, 1st reported in green monkey, was, isolated by Monlagnier et al (1983) in France and, later by Gallo et al in USA (1984)., l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 650, , l, l, l, , l, , l, , l, l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , HIV is a part of family or group of virus called, lentivirus (slow acting virus)., The major cell affected by HIV is the helper, Tlymphocyte., The HIV virus multiplies and slowly begins to, destroy the CD4 lymphocytes (Tcells or helper T, cells), which are the white bloods cells responsible, for the coordination of the entire immune system., The length of the time between initial HIV infection, and the development of AIDS (called window, period) varies greatly, and some people may remain, without symptoms for years., AIDS was first recognised in Hatai (USA) in 1981, among a group of young homosexuals who were, addicts of heroin and other narcotics and had lost, immunity competence to pneumonia and skin cancers., AIDS is the end of the disease., A number of infections (called opportunistic, infections, OIs) commonly occur at this stage and/, or cancers that occur in people with otherwise, unexplained defects in immunity. Getting on OI is, not the same thing as having AIDS. In order for a, patient who is infected with HIV to have AIDS, the, immune system must be severely damaged. The, severity of the immune system damage is measured, by a CD4 lymphocyte count. If a person infected, with HIV has a CD4 count less that 200/ml, and, have one or more of these ‘official’ OIs then the, person is said to have AIDS. (Normal CD4, lymphocytes count ranges from 600/ml to 1000/, ml). Death is due to uncontrolled or untreatable, infection., Most serious form of AIDS is known as AID related, complex (ARC) which is characterized by swollen, lymph nodes, fever, night sweats and weight loss., 25% ARC patients may develop full blown AIDS., HIV antibodies can be detected by the ELISA test, (enzymelinked immunosorbent assay)., Elisa is a technique which can detect and even, quantitate extremely small amount of a protein,, antibodies or antigens with the help of enzymes., The commonly used enzymes are perodixases and, alkaline phosphatase., A positive ELISA should be confirmed using, another test called the western blot test. Western, blot test is the culturing of blood and testing plasma, for virus., , l, , l, , Western blot test will confirm the result of repeated, test through the detection of HIV proteins., If all three tests are positive a diagnosis of HIV, infection will be given., Viral load test measures the amount of virus in the, blood which willl help in determining the probable, progression of the disease., The currently approved viral load test is called the, Amplicor HIV1 Monitor Test or PCR (Polymerase, Chain Reaction) test. Viral load tests are also used, in the management of drug treatments., , Bacterial diseases, l, , Types of bacterial diseases are – cholera,, pneumonia, plague, tuberculosis (TB), pertussis, (whooping cough), tetanus, diphtheria, typhoid,, leprosy etc., , Cholera, l, Cholera is highly communicable bacterial disease., l, Cholera is caused by Vibrio cholerae., l, Houseflies are the vectors of cholera., l, It is an acute diarrhoeal disease characterised, by vomiting, muscular cramps, anuria (no urine) &, rapid dehydration., l, Most important antibiotic for cholera are, tetracycline & chloramphenicol., l, Cholera is commonly called as Haiza., l, It is mainly a water borne diseases but also, spreads through contaminated food and drinks or, touching by contaminated hands., l, The virus mainly infects intestines and parts of, digestive tracts., l, V. cholerae produces a cholera toxin enterotoxin, which induces excessive sccretion of an isotonic, electrolyte solution by the intact intestinal mucosa., This solution is lost in the shool., l, To prevent cholera water must be disinfected with, tropical lime of chloride (TLC) or chlorogen (strong, chlorine solution)., Pneumonia, l, Pneumonia, a disease of lung, is caused by, Streptococcus or Diplococcus pneumoniae., l, It is of two types – bronchopneumonia (young, children, elderly person) & lobar pneumonia, (10–50 years)., l, Pneumonia is characterised by sudden chill, chest, pain, cough with rusty mucoid sputum, rapid, shallow breathing & high temperature.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř–, l, , Important drugs for pneumonia are, erythromycin, tetracycline & sulphonamide., , Plague, l, Plague is primarily a disease of rat., l, It is caused by rod shaped nonmotile bacterium,, Pasteurella/Yersinea pestis & spread through the, bite of infected rat flea (Xenopsylla cheopsis) on, lower extremities., l, Pasteurella pestis is endoparasite of gut of rat flea, (which are the ectoparasite of rat & mice)., l, Head louse (Pediculus) & bedbug (Cimex) may, also transmit the germ from man to man., l, Plague is also called black death. It is of 3 types –, bubonic plague, pneumonic plague & septicemic, plague., l, Bubonic plague is characterised by high fever,, weakness, enlargement of lymph nodes (especially, of armpit & groin), delerium exhaustion and, haemorrhages which turn black. The patients dies, there after. Hence plague is also called black death., l, Pneumonic plague is characterised by, haemorrhage of bronchi & lungs., l, Pneumonic plague spreads from human to human, (without ratflea) through droplets & fomites., l, Septicemic plague is characterised by anaemia,, fever, chill etc., l, Streptomycin injection & tetracycline are, effective drugs against plague bacilli., Tuberculosis, l, Tuberculosis (TB) is caused by rod shaped gram, (+) ve bacteria, Mycobacterium tuberculosis., l, Disease is spread by direct contact and droplet, method., l, Koch (1882) discovered Mycobacterium, tuberculosis., l, During infection bacteria produce a toxin called, tuberculin., l, TB is of 2 types – pulmonary & extrapulmonary., l, Pulmonary TB is characterised by fever,, coughing, chest pain, difficult breathing & blood, in sputum (haemoptysis) etc., l, Milk is a source of bovine tuberculosis., l, BCG (Bacillus Calmette Guerin) vaccine for TB, was obtained from bovine bacillus by Calmette, & Guerin in 1921., l, Antituberculosis drugs are streptomycin, PAS, (para amino salicylic acid), rifampicin, ethambutol, etc., , l, l, , 651, , Sputum, tuberculin, Xray and gastric analysis, are carried out to diagnose tuberculosis., Tuberculin test is also called mantoux test., , Pertussis, l, Pertussis or whooping cough is caused by bacillus, bacterium Bordetella pertussis or Haemophilus, pertussis., l, It is one of the most dangerous disease of, childhood., l, It is spread through droplet infection and direct, contact., l, It is characterised by mild fever, vomiting & attack, of irritating cough accompanied by inspiratory, whoop/gasp (loud crowing inspiration)., l, Most effective antibiotic for whooping cough are, erythromycin, ampicillin, chloramphenicol &, streptomycin., l, Vaccine for pertussis is available in the form of, DPT (i.e., diphtheria, pertussis, tetanus) at monthly, interval., Tetanus, l, Tetanus, an incurable bacterial disease, is caused, by Clostridium tetani., l, Its infection is acquired by contamination of, wounds with tetanus spores as these infected spores, are abundant in the soil manured with animal dung., l, Incubation period is 3 to 25 days during which, bacteria secrete a neurotoxin, tetanospasmin which, is carried to the CNS., l, Tetanus involves degeneration of motor neurons, & characterised by painful muscular contraction, of jaw (lock jaw)., l, The common symptoms are stiffness of the jaw,, difficulty in chewing and swallowing, fever,, headache, and spasm of facial muscles., l, Injection of ATS (antitetanus serum) gives passive, immunity while TT (tetanus toxoid) gives active, immunity., Diphtheria, l, Diphtheria is caused by gram (+) ve bacterium,, Corynebacterium diphtheriae., l, It is highly infectious and spread through droplet, infection and direct contact., l, Diphtheria can be diagnosed by schick test., l, Endotoxin produced by pathogen causes nasal, diphtheria, pharyngeal diphtheria &, laryngotracheal diphtheria.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 652, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , In severe cases, respiratory tract is blocked causing, difficulty in breathing & even death due to choking., Antibiotic recommended in case of diphtheria are, penicillin & erythromycin., , Typhoid, l, Typhoid is caused by Salmonella typhi., l, Bacteria responsible for typhoid is commonly, found in intestine of man., l, Typhoid spreads through food, milk and water, contaminated with intestinal discharges either, directly or through flies and personal hygiene., l, It is characterised by headache, lesion of intestinal, mucosa, haemorrhage, ulceration of intestine, rose, coloured rash on chest & upper abdomen., l, Typhoid is diagnosed by widal test., l, Antibiotic against typhoid are ampicillin &, chloramphenicol., l, Sometimes cholecystectomy is carried out to, remove the source of typhoid infection., l, TAB vaccine provide immunity for about 3 years., Peptic ulcers are eroded areas in the lining of, stomach & duodenum. It is caused by excessive, secretion of acid in gastric juice. According to, new findings ulcers occurs due to attack of, Helicobacter pylori., Leprosy, l, Leprosy (Hansen's disease) is contagious chronic, bacterial disease., l, It is caused by Mycobacterium leprae., l, Mycobacterium leprae was discovered by Hensens, (1973)., l, Presence of lepromin in skin test can indicate the, appearance of leprosy., l, Leprosy is of 2 types – tuberculoid leprosy, (involves tuberculoid granuloses formed by, aggregation of macrophages) & lepromatous, leprosy (characterised by nodular aggregates of, lipid laden macrophages, lepra cells)., l, Tuberculoid leprosy give positive test with, lepromin while lepromatous leprosy is negative to, lepromin test., l, Leprosy is characterised by hypopigmentation of, skin, thickening of peripheral nerves, numbness in, some body parts, rupturing of nodules & formation, of ulcers etc., l, Leprosy is a dreaded disease due to social stigma, attached with it., , l, , Surgery along with drugs (diaminodiphenyl, sulphone or dapsone, ofloxacin, chaulmoogra oil), can cure the disease., , Anthrax, l, Anthrax is an acute infectious disease caused by, spore forming bacterium Bacillus anthracis., Anthrax is most common in agricultural regions, where it occurs in animals., l, It most commonly occurs in wild and domestic, lower vertebrates (cattle, sheep, goats, camels,, antelopes and other herbivores), but it can also, occur in humans when they are exposed to infected, animals or tissue from infected animals., l, Anthrax infection can occur can three forms –, cutaneous, inhalation and gastrointestinal., l, Symptoms are –, –, Cutaneous : Itchy bump that resembles an, insect bite and develops into a vesicle and, then a painless ulcer within 12 days with a, characteristic black necrotic area in the centre., –, Inhalation : Common cold which may, progress to severe breathing problems and, shock. It is usually fatal., –, Intestinal : Acute inflammation of the, intestinal tract with initial signs of nausea,, loss of appetite, vomiting, fever abdominal, pain, severe diarrhoea., l, If left untreated, anthrax in all forms can lead to, septicemia and death., l, Anthrax is considered to be a potential agent for, use in biological warfare., , Diarrhoeal diseases, l, l, , l, l, l, l, l, , Diarrhoeal diseases are group of infections of the, intestinal tract., It is characterised by food poisoning, abdominal, cramps, frequent passage of stool having blood &, mucus leading to dehydration., Bacteria causing diarrhoeal diseases are E.coli,, Shigella sp., Campylobacter & Salmonella., A protozoan Giardia and certain viruses also cause, similar conditions., Rotavirus causes gastroenteritis with acute watery, diarrhoea in infants & children., Norwalk viruses causes gasteroenteritis in all age, groups., ORS is oral rehydration solution used for correcting, dehydration caused by diarrhoea in all age groups.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř–, l, , ORS contains 1.5 gm glucose,3.5 gm NaCl, 2.9 gmKCl, & 2.9 gm trisodium citrate., , Sexually transmitted diseases, l, , l, , l, l, , l, l, l, l, , l, , l, , The sexually transmitted diseases (STD) are, transmitted predominantly by sexual contact and, caused by a wide range of bacterial, viral, protozoal, and fungal agents and ectoparasites., Two types of sexually transmitted diseases or, veneral disease caused by bacteria are syphilis &, gonorrhoea., Syphilis is caused by Treponema pallidum with, incubation period of 35 week., It is characterised by lesion in the mucous, membrane of urinogenital tract, ulcers on genitalia, & swelling of local lymph nodes., Syphilis is also transmitted to foetus from infected, mother through placenta., Appropriate antibiotics recommended for syphilis, are tetracycline & penicillin., Gonorrhoea is caused by diplococcus bacterium,, Neisseria gonorrhoea., It is characterised by inflammation of mucous, membrane of urinogenital tract resulting in burning, sensation during urination., It may also lead to arthritis & eye infection called, gonococcal ophthalmia in children of gonorrhoea, afflicted mother., Antibiotics for gonorrhoea are penicillin &, ampicillin., Table : Some STD and their pathogens, Disease, Pathogen, Bacterial, Syphilis, Treponema pallidum, Gonorrhoea, Neisseria gonorrhoea, Chancroid, Haemophilus ducreyi, Vaginitis, Gardnerella vaginalis, Viral, Herpes genitalis, Condyloma acuminatum, Molluscum contagiosum, Protozoal, Trichomoniasis, , HSV2 (DNA) virus, Papova (DNA) virus, Pox (DNA) virus, Trichomonas vaginalis, , Chlamydial disease, l, l, , Trachoma is an eye disease and caused by, Chlamydia trachomatis (a primitive prokaryote)., Chlamydia trachomatis are obligatory intracellular, , l, l, l, , l, , 653, , parasite & are larger than virus., It is commonly called Rohe or kukre or kheel., It is transmitted by direct contact, fomite & flies., Trachoma is characterised by inflammation &, discharge from eyes & ulceration of cornea &, conjunctiva resulting in blindness., Trachoma is responsible for 5% of the viral, impairment and blindness in India., , Protozoan diseases, Malaria, l, Malaria is the most common protozoan disease, of human being., l, Malaria is caused by Plasmodium species & spread, through female Anopheles., l, Plasmodium is nonpathogenic to mosquito host., l, Laveran (1880) discovered malarial parasite in, blood of malarial patient., l, Pfeiffer (1892) proposed that malaria is spread by, blood sucking insect., l, Discovery of Plasmodium & its transmission by, Anopheles (female) was confirmed by, Ronald Ross (1897)., l, Different species of Plasmodium causes different, types of malaria. The species are – P. vivax, P., falciparum, P. malariae and P. ovale., l, Quotidian malaria occurs due to secondary, complication of malignant tertian or due to multiple, or mixed infection by more than one species of, Plasmodium., l, Quartan malaria caused by P. malariae is, characterised by the reccurrence of fever every 4th, day i.e., interval of 72 hours., l, P. ovale causes benign tertian malaria., l, Tertian malaria is caused by P. vivax, P. falciparum, & P. ovale., l, P. falciparum causes malignant or subtertian, or, aestivoautumnal or pernicious or cerebral or, tropical malaria resulting in high death rate due, to clumping of infected RBC & blocking capillary, blood circulation in brain, lung, heart, spleen etc., l, Black water fever, caused by infection ofP. falciparum,, resulting in the excretion of haemoglobin in urine., l, Clinical fever in malaria is due to erythrocytic, schizogony., l, Malaria is characterised by recurring rigors, lasting 6–10 hours. There are three stages –, –, Cold stage : Chill and shivering.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 654, , ŕďőĽę– ĐĽŐńŐĹť, , Hot stage : Temperature rise to 100ºC., Sweating stage : There is perspiration and, gradual fall in temperature., l, Malaria results in anaemia, toxaemia and, splenomegaly (enlarged spleen)., l, Antimalarial drugs are quinine (extracted from, bark of Cinchona tree), chloroquine, paludrine,, daraprim etc., l, Daraprim drug kills the parasitic stages present in, both liver cells & RBCs of blood., Amoebiasis, l, Amoebiasis (amoebic dysentry or enteritis) is, caused by intestinal endoparasitic protozoan,, Entamoeba histolytica of man., l, Infection is transmitted by contamination., l, Entamoeba secretes cytolysin that erodes the, mucous membane of intestine., l, It is characterised by abdominal pain, alternating, diarrohea and constipation, stool with blood,, mucous and mucous membrane pieces., –, –, , Giardiasis, l, Giardiasis or backpacker's disease is caused by, Giardia intestinalis., l, It inhabits upper part of small intestine, (duodenum and jejunum)., l, Infection is transmitted by contamination of cyst, with food and drinks., l, It is characterised by mild diarrhoea involving, passage of pale bulky, foul smelling and greasy, stool., Pyorrhoea or peridontitis caused by E.gingivalis,, is characterised by bleeding gums & falling of, teeth., Kala azar, l, Kala azar or Leishmaniasis is caused by, Leishmania donovani & spread by sandfly, (Phlebotamus)., l, Kala azar is characterised by fever & enlargement, of visceral organs., l, Kala azar is also known as dumdum fever., l, Leishmania braziliensis causes espundia with, ulcers appearing first on legs later on throat, nose, etc., l, Oriental sore is caused by Leishmania tropica., Trypanosomiasis, l, Trypanosoma is a flagellate protozoan whose, different species causes different types of, trypanosomiasis., , l, , l, , l, l, , l, , Trypanosomiasis is characterised by high fever,, swelling of neck & armpit, weakness, anaemia,, muscle spasm, lethargy, unconsciousness & death., Gambian fever or West African sleeping sickness, caused by T. gambiense, is spread by both sexes of, tsetse fly (Glossina palpalis)., Rhodesian or East African sleeping sickness,, caused by T. rhodesiense, is spread by G. morsitans., Chagas disease is also called South American, sleeping sickness. It is caused by T.cruzi & spread, by Panstrongilus sp., and Triatoma sp., It is more common in children & young adults., , Ciliary dysentry (Balantidiasis), l, Ciliary dysentry is caused by a ciliated protozoan, Balantidium coli. The latter inhabits the human, large intestine (colon). It is also seen in pigs and, monkeys. In pigs they are nonpathogenic., l, It reproduces asexually by transverse binary fission, and sexually by conjugation. The latter is followed, by cyst formation. Cysts pass out in the host’s, faeces., l, Infection occurs by ingesting cysts with food and, drinks., l, Balantidium coli causes ulcers in the colon and, invades mucous membrane by secreting an enzyme, hyaluronidase. This generally results in diarrhoea,, but may also lead to severe or fatal dysentry., l, Protection of food articles from dust and files, that, may carry cysts, can prevent human infection., l, Tetracycline or iodoquinol are effective treatments., , Helminthic diseases, l, l, , l, , Helminthic diseases are transmitted through dirty, hand, contaminated soil & food., Helminthes are multicellular parasites which causes, many diseases in man. It consists of roundworm, and flatworms., Types of diseases – are filariasis, taeniasis,, ascariasis etc., , Filariasis, l, Filariasis is caused by Wuchereria bancrofti., l, It is also known as elephantiasis due to excessive, enlargement of body part like legs., l, It is characterised by fever, proliferation of, endothelial cells & deposition of metabolites in the, wall of lymph vessels., l, Secondary host of filariasis is Culex or Aedes, mosquitoes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř, , Taeniasis, l, Taeniasis is caused by intestinal endoparasite of, man called Taenia solium., l, The disease accompanied by abdominal pain,, indigestion, loss of appetite (anorexia), nausea,, vomiting etc., l, Cysticerci larva of Taenia causes cysticercosis, which causes damage to different body parts,, blindness (in eyes), epilepsy like fits in brain., Ascariasis, l, Ascariases, caused by A.lumbricordes is more, common in children., l, Ascaris is intestinal endoparasite of man., l, Vectors for ascariasis are flies & cockroaches, containing embryonated eggs of Ascaris, contaminated with food and water., l, Ascariasis is characterised by colic pain,, indigestion, diarrhoea, vomiting, weakness, retarded, physical or mental efficiency etc., l, Scratch test, dermal test & stool test can be done, to detect the roundworm infection (Ascaris)., Other diseases, l, Enterobiasis, ancylostomiasis, trichinosis, &, schistosomiasis (also called bilharzia) are caused, by Enterobius vermicularia (pin or seat worm),, Ancylostoma duodenale (hook worm), Trichinella, spiralis (trichina worm) & Schistostoma, haematobium (blood fluke) respectively., l, Enterobius vermicularis (Oxyuris) is found in large, intestine and appendix, causes anal itching,, appendicitis, nervous problem. No intermediate, host. Transmission is direct by contaminated food., l, Trichinella spirillis is found in the human intestine,, causes muscular pains and pneumonia or, Trichiniasis. It is transmitted by eating infected pork., l, Schistosoma haematobium is transmitted by snail., It is found in urinary baldder, blood vessels and, caused itching rashes aches, fever and eosinophilia., l, Dracunculus medinensis (Guinea worm) are found, in the subcutaneous tissues of body. It causes, Guinea worm disease, characterised by blisters, on skin. Like small pox it is considered to be an, extinct disease in India., l, Loa Loa (The eye worm) is found in the, subcutaneous tissues of eyes, causes conjunctivitis., l, Trichuris trichura (whip worm) is found in the, caecum and appendix, cuases anaemia, bloody, stools and pain., , 655, , Table : Some diseases and their confirmatory, immunological tests, Test, Disease, Ames test, Carcinogenicity, Dick test, Scarlet fever, Mantoux text, Tuberculosis, RoseWaaler test, Rheumatoid fever, Schick test, Diphtheria, Wassermann test, Syphilis, Widal test, Typhoid, Wayson stain test, Plague, Tourniquet test, Dengue fever, Presence of lepromin in skin Leprosy, , NONCOMMUNICABLE DISEASES, l, l, l, , l, , l, l, , l, , l, , l, , Noncommunicable diseases develops in persons, suffering from them., These diseases are noninfectious as these do not, spread from infected persons to healthy one., On the basis of their causative agent non, communicable diseases are of the following types –, deficiency, degenerative, cancerous and allergy., Deficiency diseases occur due to absence of those, factors which are important in body growth and, development., These are of two types hormonal and nutritional., Hormonal diseases occur due to hypoactivity or, damage to endocrine gland, e.g. diabetes insipidus, caused due to hyposecretion of vasopressin secreted, by posterior lobe of pituitary gland and diabetes, mellitus caused by hyposecretion of insulin secreted, by pancreas., Nutritional deficiency diseases are kwashiorkar, (protein deficiency) and pellagra (vitamin B5niacin, deficiency)., Degenerative diseases occur due to degenerative, changes in some vital organs of the body. These are, of following types – like cardiovascular disease,, brain disease and arthritis., Allergies are caused when the body which has, become hypersensitive to certain foreign substance,, comes in contact with that substance. Hay fever is, an allergic disease., , Cardiovasular diseases, l, l, , Cardiovascular diseases are degenerative diseases, of heart and blood vessels of the body., Heart diseases are the most common cause of, deaths in human beings in the present century.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 656, , l, l, , l, , l, l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Arteriosclerosis is the most common type of, cardiovascular disease., It occurs in elderly person whereby the arteries, thicken and lose their elasticity due to hardening, and thickening of fibrous tissue which lead to, hypertension causing cerebral or visceral, haemorrhage., Atherosclerosis is narrowing of arteries and, arterioles due to insolubilisation and deposition of, cholesterol inside and over the intima., Enzyme paraoxonase present in blood checks, cholesterol deposition., Rheumatoid heart disease (RHD) is caused by, the toxins produced due to repeated attack of, rheumatic fever (due to Streptococcal infection of, throat)., RHD is characterised by damaged heart walls,, heart muscles, scarring and malfunctioning of heart, valves especially atrioventricular one., Hypertensive heart disease are caused by, increased blood pressure (continuous hypertension), which may lead to heart attack., Hypertension and hypotension is characterised, by persistent high and low blood pressure, respectively., Main cause of hypertension is obesity,, arteriosclerosis, mental and emotional stress etc, resulting in nephritis, stroke etc., Heart attack is failure in working of heart due to, valvular obstruction or degeneration, blood, insufficiency or myocardial infarction., It involves the irregular pulse, pain in chest in, the area of heart, murmur, constant high/low, blood pressure etc., Myocardial infarction is necrosis or death of a, part of myocardial tissue/middle layer of heart wall,, due to reduced blood supply., Coronary heart disease are characterised by, impaired heart function due to reduced blood flow, to the heart., Blood flow may be reduced to heart due to, hardening and narrowing of coronary arteries, and coronary thrombosis., Thrombosis is the appearance of blood clot causing, vascular obstruction at the point of its formation., Thrombosis occur in coronary arteries is called, coronary thrombosis & if it occurs in brain, it is, called cerebral thrombosis., , l, , l, , l, l, , l, l, l, , l, l, l, , l, , l, , Coronary thrombosis is occulsion of coronary, vessel by a clot of blood, stoppage of blood supply,, causing cardiac tissue necrosis leading to heart, attack., Anticoagulant drugs like TPA (tissue plasminogen, activator) and streptokinase are effective if given, within 4 hours of attack. Disprin is also used on, regular bases., Angina pectoris is a severe temporary cardiac pain, due to decreased blood supply at the time of stress., The pain arise as a result of cramp may spread out, from the centre of the chest to the neck, jaws, arms, (especially left) & back., Angina occurs when heart needs more blood., Vasodilator drugs like nitroglycerin are effective, to give immediate relief from angina pain., Heart disease and heart attacks can be reduced by, taking low cholesterol diet, avoiding smoking,, alcohol, becoming obese, overwork, tension free, work etc., Arrhythmia is irregular heart beat due to atrial, fibrillation, atrial flutter, heart block etc., Atrial fibrillition means rapid random atrial, contraction causing irregular ventricular beats., Atrial flutter's is regular rapid contraction but, submultiple ventricular contraction. Atrial rate is, 200300/min., In flutter (as compared) to fibrillation the frequency, of irregular heart beat is much higher (about 300, 500 per min) and is more difficult to treat and, hence more dangerous., Varicose vein are unusually distended vein which, develops due to excessive stretching and, inflammation of vein wall. The causes for this, conditions are heredity, obesity, excessive sitting,, standing etc., , Stroke, l, , l, , l, , Stroke [cerebrovascular (brain blood vessel), accident or CVA] is the most common, degenerative disease in man., Stroke is a brain damage due to stoppage of blood, supply resulting from cerebral thrombosis, cerebral, haemorrhage, cerebral embolism and sustained, contraction or spasm of an artery., Cerebral haemorrhage is rupturing of an artery, due to weakening of its wall & hypertension (high, blood pressure).
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř–, l, , l, , Embolism is the sudden blocking of an artery by, a clot or foreign materials like air, fat etc. which, has been brought by the blood from another vessels, & forced into a smaller one., Stroke is characterised by degeneration of motor, neurons of brain due to reduced supply of oxygen, resulting in paralytic attack of some body part, especially limb, loss of memory, speech, hearing, and even death., , Arthritis, l, l, l, l, , l, , l, , l, l, , l, l, l, , l, , Arthritis is a common disease of old age in which, inflammation of the joints occurs., Arthritis is of several types rheumatoid arthritis,, osteroarthritis and gout., Rheumatoid arthritis generally attack woman, (between 2040 years)., It generally involves the chronic painful, inflammation of the synovial membrane of the, joints resulting in stiffening of joint and painful, movements. In severe cases, it eventually results in, crippling deformalities., Rheumatoid arthritis is believed to be caused by, bacterial infection that provides an antibody called, rheumatoid factor or macrogammaglobulin., Osteoarthritis is degenerative arthritis where, secretion of synovial fluid decreases and bone, head develops excrescences (bony/fibrous, extensions) that limit movements causing joint, fixation (ankylosis)., It is common in old persons, mainly affecting, weight bearing joints., Gout is a diet related disease. Person suffering, from gout should avoid meat which are a rich source, of nucleic acids including purines., Gout is an inherited disorder of purine, metabolism, occurring especially in men., Gout develops when no uric acid is excreted from, the body., It occurs due to accumulation of uric acid crystals, in the synovial joints. (especially joint of great, toe)., It is characterised by sudden acute pain especially, in great toe accompanied by swelling, chill, fever,, headache, tachycardia., , Cancer, l, , A group of diseases characterised by uncontrolled, mitotic division of cells having ability to invade, , l, l, , l, , l, l, l, , l, l, , l, , l, l, , l, , l, , l, l, , 657, , other tissues or parts of body is called cancer., Cancer is not a contagious disease., Cancerous cells have high invasiveness (ability to, rapidly grow, infiltrate into blood vessels and, subsequently spread to other parts of the body, especially to metabolic organs like liver)., Neoplasm (also called tumor) is a new abnormal, tissue which is capable of continued growth,, formation of tumor and disruption of normal cells., All tumors are not cancerous., Tumors may be benign and malignant., Benign tumor is a large localised mass of abnormal, tissue enclosed in connective tissue which does, not invade adjacent tissue., Malignant tumor is not encapsulated and is capable, of invading adjacent tissues and distant sites., Metastasis is a spread of cancerous cells from one, part of the body to other part through blood, lymph, and secondary form of malignant tumor., Symptoms of cancer are –, –, Thickening or lump in the breast or any other, part of the body, –, Changes in bowel or bladder habits, –, Obvious change in a wart or mole, –, A sore that does not heal, –, Nagging cough or hoarseness, –, Indigestion or difficulty in swallowing, –, Unexplained changes in weight, –, Unusual bleeding or discharged., Types of cancers are carcinoma, sarcoma,, leukemia and lymphoma., Carcinoma is a cancer of epithelial tissue and, their derivatives like mucous membrane, skin, lungs,, breast etc., Sarcoma is a cancer of primitive mesodermal, tissue like connective tissue, bone, muscle, lymph, nodes etc., Depending upon the tissue involved, sarcoma is of, following type –, –, Fibrosarcoma – fibrous connective tissue, –, Liposarcoma – adipose tissue, –, Chondrosarcoma – cartilage cells, –, Osteosarcoma – bone, –, Leiomyosarcoma – smooth muscles, –, Rhabdomyosarcoma – stripped muscles, Ewing sarcoma (family of tumors) and Kaposi’s, sarcoma are the common types of sarcomas., Leukemia is a blood cancer. It involves the
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 658, , l, , l, l, , l, l, l, , l, , l, , l, , increased WBC count (200,000, Cell, 1000,000/mm 3) of blood due to, Due to gene mutation, increased formation in the blood, & carcinogens like soot,, marrow resulting in decreased, Uncontrolled mitotic, coal tar, cadmium oxide,, division, erythropoiesis and RBC count., aflatoxin etc., In myelocytic leukemia (9th and, Abnormal mass capable of, Neoplasm continued growth, formation, 22nd chromosomes bring their, of tumor & disrupt normal cells., jump ing, genes, together), erythroblastic tissue of bone marrow, Irregular mass of relatively, Tumor, undifferentiated cells., degenerates followed by bleeding at, different places with enlarged tonsils, May be, and cervical glands., Vincristin and vinblastin drugs, (Cancerous), (Non cancerous), ob ta ined from C athar anthus, Benign, Malignant, rosesus are effective in controlling, (not, encapsulated), (encapsulated), leukemia., Bone marrow grafting is used for, Does not, Large mass, invade adjacent, of abnormal, the treatment of leukemia., tissue, tissue, Lymphomas affect the lymphatic, Invade adjacent tissue/, system, a network of vessels and nodes, other metabolic organs, that acts the body’s filter., like liver etc. by spreading, Protooncogenes are inactive cancer, through blood, lymph., genes., Cancer, Oncogenes (active forms of proto, Types, oncogenes) are cancer causing genes., Carcinogens are factors or physical, Carcinoma, Sarcoma, Leukemia, or chemical agents which induces the, cancer growth, e.g. coal tar, asbestos,, Cancer of epithelial, Cancer, of blood, Cancer of, cells.Eg. skin, lungs,, mesodermal, cadmium oxide, aflatoxin etc., breasts etc., tissue like, Anticarcinogens occurring in green, connective, yellow vegetables, fruits and milk, tissue, bone,, muscle, lymph etc., prevent the action of carcinogens., Some viruses, parasites and, On the basis of tissue involved, excessive secretion of hormones are, Osteoma, Lymphoma, Lipomas, believed to produce cancer. Eg. cervix, (lymph vessel) (adipose tissue) (bone), cancer is caused by virus., The carcinogens are of following, Flow chart : Cancer at a glance, three types –, –, Agents causing alterations in the genetic, l, Cancerassociated genes can be divided into the, material (DNA), resulting in oncogenic, following three categories –, transformation, e.g., radiations and certain, –, Genes that induce cellular proliferation, e.g.,, chemicals., genes encoding growth factors, growth factor, –, Tumor promoters that promote proliferation, receptors, transcription factors etc., of cells, which have already undergone genetic, –, Genes that inhibit cellular proliferation (tumor, alterations, e.g., some growth factors and, suppressor cells)., hormones., –, Genes that regulate programmed cell death, –, Cancer causing DNA and RNA viruses (tumor, (apoptosis)., viruses)., Metastasis, , l, , ŕďőĽę– ĐĽŐńŐĹť
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ►ŐŇŇŐň– ŘśŇďň– ▼ĽřĚďřĚř–, l, , l, , l, , l, , Apoptosis, referred to as programmed cell death is, another intricate piece of the cell cycle. Apoptosis, is a distinct form of death that is a programmed, event and occurs in response to certain stimuli., Apoptosis is essential for normal tissue, development. In addition, this system allows cells, to selfdestruct after detecting DNA damage rather, than perpetuating mutations that might be lethal to, the whole organism., Examples of tumor supressor genes are –, –, Wilms Tumor – Involved in Wilms tumor of, the kidneys (nephroblastoma). Appears to shut, down division of a small subset of kidney, cells during development., –, BRCA1 Inheritable breast cancer (5%) &, ovarian cancer. Codes for a protein that binds, strongly to DNA, inhibiting an enzyme, involved in DNA breakage., –, p53; a transcription factor that blocks entry, into S phase if there is DNA damage. If there, is too much damage to repair, it causes, apoptosis., Other cancer genes includes –, –, Telomerase : Activation of telomerase is, necessary for immortality, –, Angiogensis genes : Tumors need to promote, the growth of new blood vessels to support, their growth, –, Metastasis genes : Proteinases to cut through, the extracellular matrix, etc., Cancer of stomach is the most common cancer, in both male & female human beings., Table : Some cancercausing agents and, their targets, Carcinogen, Soot, Coal tar (3, 4benzopyrene), Cigarette smoke, (Nnitrosodimethylene), Cadmium oxide, Aflatoxin (a mold metabolite), Mustard gas, Nickel and chromium, compounds, Asbestos, Diethylstibestrol (DES), Vinylchloride, , Target tissue, Skin and lungs, Skin and lungs, Lungs, Prostate gland, Liver, Lungs, Lungs, Lungs, Vagina, Liver, , l, , l, , l, , l, l, l, , l, , l, l, , l, , l, , l, , l, , 659, , The most common cancers in India are mouth, throat cancer in men and uterinecervical cancer, in women., Cancer can be diagnosed by biopsy of tissue,, endoscopy (gastroscope for stomach and, laproscope for pelvic region), Xrays, ultrasound., Therapy used in the treatment of cancer are, radiotherapy, chemotherapy and hormonal, therapy., In radiotherapy cancerous parts of body is exposed, to radioactive isotopes., The biological effect of radiation depends on the, amount of energy absorbed per unit mass., Chemotherapy involves the use of chemicals/drugs, which are more toxic to cancer cells than normal, cells., Chemotherapy have many side effects like, vomiting, nausea, loss of hair, shortness of breath,, constantly tired, feeling anxious or tense, loss of, weight etc., Taxol is anticancer drug obtained from, Taxus baccata., In hormonal therapy hormone causing cancer is, treated with another hormone which neutralizes the, carcinogenic hormone. Eg. breast cancer can be, controlled by testosterone., The major advantage of hormonal therapy over, chemotherapy is the less severe side effects than, those associated with cytotoxic drugs., Pap's test is originally developed to detect the, cancer of cervix and barium test is performed for, alimentary canal., Ames test is a routine screening test developed by, Bruce Ames to know the mutagenicity and, carcinogenic nature of substance., Most cancers are treated by combination of surgery,, drugs & radiation therapy., , Occupational diseases, l, , l, l, , l, , Occupational diseases arises among those people, who are exposed to air pollutants generated from, the industries where they are working., Types of occupational disease are: asbestosis,, silicosis, byssinosis, bagassosis, anthracosis., Asbestosis is characterised by pulmonary fibrosis, leading to respiratory unsufficiency & death,, carcinoma of bronchus & gastrointestinal, tract etc., Silicosis is characterised by dense nodular fibrosis,, impart of total living component etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 660, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Byssinosis is characterised by chronic cough,, progressive dyspnoea, ending in chronic bronchitis, & emphysema., Bagassosis is characterised by breathlessness,, cough, haemoptysis & slight fever., Anthracosis is characterised with little ventilatory, impairment, progressive massive fibrosis causes, severe respiratory disability & results in premature, death., All these diseases are caused by dust, called, pneumoconiosis., , l, , l, , l, , Pneumoconiosis may gradually cripple a man by, reducing his working capacity due to lung fibrosis, and other complication., Oxides of sulphur & its hydrates, H2SO4 in moderate, concentration cause suffocation & irritation in the, upper respiratory tract & continuous exposure, causes lung diseases like chronic asthma, bronchitis, etc., Carbon dioxide causes headache, dizziness,, palpitation, tickering before eyes & finally it may, lead to collapse, unconsciousness & even death., , Some other Animal Diseases, Ø, , Ø, , Ø, , Ø, , Ø, , Rinderpest, Rinderpest is an acute, usually fatal, contagious viral disease principally of cattle. The disease affects the gastrointestinal, and respiratory systems. It is a devastating disease of cattle and some wild artiodactyls (African buffalo, giraffe, eland and, kudu) with death rates during outbreaks approaching 100%. Rinderpest is caused by a virus (a single stranded RNA virus),, belonging to the family paramyxoviridae, genus morbilli virus. Virus is found in expired air, eye and nose discharges,, saliva, faeces, urine and milk. Transmission is mainly through aerosols. Rinderpest virus is a relatively fragile virus. Sunlight, is lethal, and the vaccine must therefore be kept in a brown bottle and protected from light; virus in a thin layer of blood, is inactivated in 2 hours. Moderate relative humidity inactivates the virus more quickly than either high or low humidity., The virus is very sensitive to heat, and both lyophilised and reconstituted virus should therefore be kept cold; lyophilized, virus stored at –20°C is viable for years. Rinderpest virus is rapidly inactivated at pH 2 and 12 (10 minutes); optimal for, survival is a pH of 6.5 7. The virus is inactivated by glycerol and lipid solvents., Foot and mouth disease, Foot and mouth disease (FMD) is an acute, highly contagious picornavirus infection of cloven animals (pigs, sheep, cattle,, goats, deer etc). The virus (FMDV) is sensitive to environmental influences, such as pH less than 5, sunlight and dessication,, however it can survive for long period of time at freezing temperatures. The disease is highly contagious and may spread, over great distances with movement of infected or contaminated animals, products, objects and people. It causes vesicles, or blisters on the feet and in the mouth and on the nose. The animals become sick (fever, loss of appetite, salivation,, depression and young animals can die) and lose productivity., Cowpox, Cowpox is a contagious viral disease of cows and is mild form of smallpox. Cowpox virus is related to the virus of smallpox., Also called variola, it is characterised by pustular lesions on the teats and udder. Cowpox is transmitted by contact, inducing, a mild infection of the hands in persons who milked infected cows, Coccidiosis, Coccidiosis is an infection caused by a protozoan (onecelled organism) called coccidia. Unlike most reptile endoparasites, (those that live inside the host), coccidia are not worms; but live in the actual cells of the intestine walls. A bad infestation, of coccidia can cause diarrhoea and for this reason may be mistakenly identified as a worm problem., Tick Fever, Tick Fever is an illness caused by a virus carried by small mammals, such as ground squirrels, porcupines, and chipmunks,, and by ticks. Tick fever (babesiosis) is an important disease of cattle. The disease was probably introduced as early as 1829, with cattle from Indonesia infested with the cattle tick Boophilus microplus.Babesiosis is caused by two organisms : Babesia, bovis and Babesia bigemina. Of the two species, B bovis is by far the most important, causing about 80 per cent of, outbreaks and an even higher percentage of deaths. Both Babesia species are single cell organisms that develop in the red, blood cells of cattle and are transmitted in Australia by the cattle tick Boophilus microplus. Transmission of B bovis takes, place when engorging adult female ticks pick up the infection, pass it on to their progeny (larval or seed ticks) which, in, turn, pass it on when feeding on another animal. Transmission of B bigemina is also from one generation of ticks to the, next but with engorging adult ticks picking up the infection and nymphal and adult stages of the next generation passing, it on to other cattle.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 661, , ▲ĽŐŇĚęĽĘďń– ♀ĚĘĺňŐńŐĹĽĚř–, , Chapter 73, , Biomedical Technologies, l, , l, l, , l, , Biomedical technology involves the application, of engineering and technology principles to the, domain of living or biological systems., Usually biomedical denotes a greater stress on, problems related to human health and diseases., Biomedical engineering combined with, biotechnology is often called biomedical, technology or bioengineering., Examples of concrete applications of biomedical, , l, , l, , engineering are the development and manufacture, of biocompatible prosthesis, medical devices,, diagnostic devices and imaging equipment such as, MRIs and EEGs, and pharmaceutical drugs., With the advancement in the field of science and, technology a number of new techniques and, sophisticated instruments have come to help in, accurate diagnosis of diseases., Techniques and instruments which are free from, Biomedical technologies, , Biomedical techniques, , Diagnostic lab test, Divided into, , Invasive, When causes discomfort to, patient or injury to the tissue., Eg. Endoscope, Xray (if, repeated rapidly), , Diagnostic, Instrument, EEG, ECG, EPs, SQUID,, MET, autoanalyzer, , Noninvasive, When these are free from, risk or injury to body., Eg. ECG, EEG, EPS, MRIs, etc., , Imaging, Instrument, CT Scan, PET, MRI,, ultrasound imaging,, Xray imaging, , Implants, ∙ Artificial heart valves, ∙ Vascular grafts, , Disposables, Oxygenator, , Bubble, , Devices, , Therapeutic, Instrument, Pacemaker, medical lasers,, Intraaortic, balloon pumping, , Types, , Liquid, , Three, categories, , External, Prosthesis, Limb prosthesis, Film, , Membrane
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 662, , l, , ŕďőĽę– ĐĽŐńŐĹť, , risk of injury to body are called noninvasive, eg., ECG, EEG etc., Instruments which causes discomfort to the, patient are called invasive, eg. endoscope etc., , DIVISION OF BIOMEDICAL, TECHNIQUES, l, , l, , Biomedical techniques are divided into diagnostic, instruments, imaging instruments, therapeutic, instruments and devices., , Diagnostic instruments, Electroencephalogram (EEG), l, Electroencephalograph is an electricity operated, instrument having electrodes which when attached, to scalp gives information about the electric waves, emanating from different parts of brain., l, Electroencephalogram is recording of electrical, potentials originating from different parts of the, brain in the form of waves., l, The electrical activity of the exposed animal brain, was discovered by Satton in 1875., l, This device is used to assess brain damage, epilepsy, and other problems. EEG can also be used in, conjunction with other type of brain imaging., l, This test is only one part of the investigation into, diagnosing epilepsy. Further information on how, epilepsy is diagnosed can be obtained through, epilepsy action., l, Neuroscientists and biological psychiatrists use, EEGs to study the function of the brain by recording, brain waves during controlled behaviour of human, volunteers and animals in lab experiments. Theories, to explain sleep often rely on EEG patterns recorded, during sleep sessions., l, Historically four major types of brainwaves are, recognized – alpha, beta, delta and theta., l, Alpha is the frequency range from 8.5 Hz to 12, Hz. It’s often associated with an alert adult and, is present by the age of two years. Alpha rhythms, are best seen with the eyes closed. It attenuates, with drowsiness and eyes open., l, Beta is the frequency range above 12 Hz. It’s often, associated with active, busy or anxious thinking, and active concentration. It is a smaller and faster, wave., l, Theta is the frequency range from 4.5 Hz to 8 Hz, , l, l, , and is associated with drowsiness, childhood,, adolescence and young adulthood. Theta can also, be produced by hyperventilation in people without, it being an abnormal phenomena., Delta is the frequency range up to 4 Hz and is often, associated with the very young and certain, encephalopathies and underlying lesions. It is, seen in sleep, but generally is associated with other, frequencies to become waveforms such as vertex, sharp waves., Delta waves indicates brain disorders., Significance of EEG, –, EEG is used to diagnose epilepsy and other, seizure disorders. In epilepsy abnormal, discharges of certain neurons cause excessive, electrical activity that interferes with the, normal functioning of brain. EEG helps to, detect and locate the specific regions., –, EEG is used to study normal brain activity as, well as to diagnose brain infections, metabolic, and drug effects, sleep disorders, degenerative, diseases, hematoma, trauma, brain tumors,, drug induced hypothermic necrotic and periods, of unconsciousness and confusion., –, EEG is used to determine the brain death also., When there is complete absence of brain waves, in two EEGs taken 24 hours apart, it is, considered as brain death., , Evoked potentials, l, Evoked potentials (EPs) is a measure of the brains, electrical activity in response to sensory stimuli., l, EPs is obtained by placing electrodes on the surface, of the scalp, repeatedly administering a stimulus, and then using a computer to average the results., l, It is a diagnostic tool used to evaluate the function, of the central nervous system., l, An evoked potential is also known as an evoked, response., l, An evoked potential test measures the electrical, signals sent by the brain when nerves are stimulated., These are called evoked responses., l, The most common types of evoked potential tests, are visual, auditory (hearing), and somatosensory,, which refers to the pathway of nerve impulses, between the limbs and the brain., l, Evoked potential tests can be used to diagnose, diseases of the nervous system, such as multiple, sclerosis, that affect the patient’s response time
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚęĽĘďń– ♀ĚĘĺňŐńŐĹĽĚř, , because of damage to the nerves. They are also, used to diagnose hearing loss, vision loss caused, by optic nerve damage, and to test brain response, in infants and abnormal electrical discharges in, people with epilepsy., Electrocardiogram, l, Electrocardiograph (ECG) is a noninvasive, instrument employed to record myoelectrical, changes during cardiac cycle., l, Electrocardiogram is the recording of electrical, potential produced during cardiac cycle from, initiation and spread of cardiac impulse from SA, node to AV node., l, The waves produced in ECG are known as P, Q,, R, S and T., –, P wave : Represents depolarization of the, atria., –, PR interval : Interval from first atrial, depolarization to the beginning of the Q wave., It decreases when heart rate increases and vice, versa. A longer PR interval may indicate that, conduction velocity through the AV node is, slowed (e.g., heart block)., –, QRS : Represents depolarization of the, ventricles. Note that there is no wave that, represents repolarization of the atria; atrial, repolarization is masked by the large QRS, complex., –, QT interval : QT interval is measured from, the beginning of the Q wave to the end of the, T wave. It represents the entire period of, depolarization and repolarization of the, ventricles., –, ST segment : This is the segment from the, end of the S wave to the beginning of the T, wave. It represents the period when the, entire ventricles are depolarized., –, T : Represents repolarization of the ventricles., l, This method causes no discomfort to a patient, and is often used for diagnosing heart disorders, such as coronary heart disease, pericarditis or, inflammation of the membrane around the heart,, cardiomyopathy or heart muscle disease, arrhythmia, (heart rhythm problems), changes in the electrical, activity of the heart caused by an electrolyte, imbalance in the body and coronary thrombosis., l, The electrocardiography is a painless and quick, procedure., , l, l, , l, , l, , l, , 663, , Einthoven is father of electrocardiography., Echocardiography is sonographic (ultrasound), imaging of heart, great vessels like aorta, heart, valves, heart wall etc. to know any abnormality. It, is also used to record blood flow velocity and blood, turbulence., Multichannel monitor measure and display the, ECG, blood pressures in various heart chambers, and other physiological data., Doppler echocardiography is a technique which, allows the indirect measurement of the flow of, velocity as it passes through the heart., Vectorcardiography is employed for analysis of, Q wave and intraventricular conduction, abnormalities., , SQUID and Autoanalyser, l, SQUID is superconducting quantum interference, device, e.g. magnetoencephalograph., l, SQUID and MET (magnetoencephalographic, technique) give information about the health of, various parts of the brain., l, Autoanalyser is a fully automatic, computerised, instrument which can analyse qualitatively and, quantitatively various biochemicals present in, body fluids like urea, uric acid, ketones, cholesterol,, glucose, proteins, enzymes etc., The abbreviation EMG is for electromyogram, a, recording of electrical activity in muscle. In case, of nerve injury, with the help of EMG the actual, site of nerve damage can often be located., , Imaging instruments, Ultrasound imaging or sonography, l, Sonography is a noninasive technique which uses, ultrasound for producing images of internal, body parts., l, Ultrasound is sound beyond human hearing, power or above 20,000 Hz or 20 kHz., l, Diagnostic ultrasound used in sonography has a, frequency of 1 – 15 MHz (MHz = 1 million, oscillations/sec)., l, Ultrasound is produced through piezoelectric, effect. It is based on the principle when an electric, potential is applied to crystals of lead zirconate,, they get excited and start vibrating. These vibrations, are the source of the production of ultrasound., l, Sonography is also known as ecography. The, visual record is known as echogram or sonogram.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 664, , l, l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Ultrasound has wide applications in medicine and, is especially useful in obstetrics., In obstetrics it is used to the study the age, sex, and level of development of the foetus and to, determine the presence of birth defects or other, potential problems., Sex determination of foetus by sonography is now, banned under prenatal diagnostic techniques act,, 1994., Doppler ultrasound scanning is used in scanning, blood flow in vessels, blood clots and heart, abnormalities., , Xray imaging, l, Xrays are highly penetrating electromagnetic, radiation of extremely short wavelengths or high, frequency (i.e. high energy). It is because of their, high energy, Xrays can penetrate through many, objects., l, When a beam of Xrays is directed at a part of the, body such as chest, the rays are absorbed more by, dense structures such as the ribs or heart muscles, than by less dense structures such as the skin or, lungs., l, Xray imaging is commonly employed for, diagnosing diseases of the heart, lungs and, detection of bone and joint injuries., l, Xray imaging is the oldest and perhaps also the, most common medical imaging method which, began with the accidental discovery of Xray by, William Kornad Roentgen, a German Physicist, in 1895., l, The branch of science that deals with the study of, Xrays for detection and treatment of diseases is, called radiology., l, However there are differences in penetration, through different materials due to the differences, in the material densities. For example, Xrays can, penetrate through fat/muscle/soft tissues of the body, easier than through bone, which is the basis for, imaging the body with Xrays. Xray imaging is, usually applied in detecting bone factures and, dislocations., l, The Xray imaging technique has some drawbacks,, e.g., the plain Xray images fail to differentiate, soft tissues and superimpose a number of structures, from front to back on the image. Moreover, the, images are not sharp to study the internal organs, in detail. Xray imaging is potentially harmful, , l, l, , l, l, , specially when the body is repeatedly exposed to, it. Therefore, this technique is invasive., The introduction of contrast Xray imaging, techniques increases the usefulness of Xrays., Most commonly used contrast Xray techniques, are urography, barium Xray examinations and, angiography., Urography is performed to obtain Xray pictures, of the urinary system., Barium Xray examination is useful to investigate, the digestive tract., , CTscanning, l, CT scanning (Computerised / Computed, Tomographic Scanning) is an invasive, radiographic technique which passes short Xrays, through the patient’s body., l, CAT (Computerised axial tomography) scanner is, specialised radiological technique (Xray) for study, of various parts inside the skull., l, Now CAT is replaced by CT scanning., l, CT scanning employs more than 30,000, 2 4 mm, beams of Xrays falling into different horizontal, planes and the images picked up by special Xray, detectors., l, It uses low level of radiations so that radiation, damage is little., l, The technique is useful in diagnosis of disorders, in any body part like abdomen, chest, spinal, cord, brain, tumors, oedema etc. It is commonly, used to investigate the brain following a stroke., l, CT scan is advantageous than simple Xrays, studies as it provides more detailed information., CT scan uses Xrays but the images are stored in, a computer. The computer is used for constructing, the 3 d images instead of directly recording them, on a photographic paper as in Xrays., l, CT was first developed by a scientist Godfey, Hounsfield in 1968 who got a Nobel prize in, 1979., , PET, l, , l, , PET (Positron Emission Tomography or Positron, Emission Tomographic Scanning) is a diagnostic, technique based on detection of positrons, (positively charged electrons) emitted by radio, isotopes such as 11C, 13N, 15O and 18F generated by, the cyclotron., These radio isotopes are then incorporated by chemical
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚęĽĘďń– ♀ĚĘĺňŐńŐĹĽĚř, , l, , l, l, , l, , l, , l, , MRI, l, , l, l, l, , l, , l, , methods into biological molecules such as glucose,, amino acids, carbon dioxide and ammonia and then, injected in very small amounts into or inhaled by the, experimental animals or human subjects., These positron emitting compounds are injected, into the bloodstream and are taken up in greater, concentration by areas of tissues that are more, metabolically active., Specific centres in brain, like colour processing in, visual cortex of humans can be detected by PET., PET is useful in measuring, –, Metabolic rates, –, Regional blood volume and blood flow, –, Area of abnormalities like disease and defects, –, Identification of specific centres in brain like, colour processing in visual cortex of humans., PET scanning provides threedimensional images, that reflect the metabolic and chemical activity of, tissues being studied., PET scanning is used for detecting tumors, for, locating the origin of epileptic activity within brain, and for examining brain function in various mental, illnesses. It is used to study epilepsy, schizophrenia,, Parkinson’s disease and drug addiction., PET scanning was developed by Louis Soko Loff, of USA in 1985., MRI (Magnetic Resonance Imaging) is a non, invasive technique which uses strong magnetic, field for generating resonance and low radio, frequency in protons present in the body., The most common protons are 1Hnuclei of water, molecules that form 70 – 80% of body., Nuclei of carbon, phosphorus and sodium can also, produce magnetic resonance., MRI detects water because it focuses on the, behaviour of hydrogen atoms in water molecules., This allows MRI to distinguish between water poor, and water rich tissues. Therefore, tissues surrounded, by bones (water poor), such as spinal cord (water, rich) are readily observable in MRI., MRI is used to detect tiny lesions of multiple, sclerosis on brain and spinal tissue, joint injuries,, slipped disc in the spinal column and minute, cancerous tumors., MRI can map internal tissues, highlight pathological, changes and study tissue metabolism with the help, of spectroscopy., , l, , l, l, , l, , l, , 665, , MRI is superior to CT and PET because (i) No, ionising radiations are employed. (ii) MRI gives 2, and 3 dimensional pictures. (iii) Images can be, obtained from any plane instead of only cross, sectional area. (iv) Study of tissue metabolism (PET, gives information of regional metabolism rate, CT, only static anatomic images), brain and heart, functions. (v) It gives a better contrast of soft tissues., (vi) MRI can be used to study blood flow. (vii) It, provides better information about infections,, cancers and tumors., However, MRI cannot be used in patients fitted, with pacemakers and metal implants., Functional magnetic resonance imaging (fMRI), is used to visualize brain function, by visualizing, changes in chemical composition of brain areas or, changes in the flow of fluids that occur over, timespans of seconds to minutes., Patients with internal ferromagnetic (metallic, iron) devices such as a pacemaker, metal cardiac, valve or metal in the area of the examination cannot, be scanned. The powerful MRI magnets would, interfere with these metal devices. In this patient, CT scan is performed., Medical use of MRI was first reported by Raymond, Damadian., , NMR, l, NMR (Nuclear Magnetic Resonance Imaging), was first discovered by Purcell and Bloch working, independently in 1952., l, The basis of this technique is that the magnetic, resonance generated by the nuclei of hydrogen, atoms is subjected to an external magnetic field., (The hydrogen atoms are present in abundance in, all the biological tissues)., l, The external strong magnetic fields required for, NMR are obtained by using either large water cooled, resistive magnets or superconductive magnets using, liquid helium., l, The imaging NMR technique is superior to CT, scanning technique in two ways –, –, It does not use iodised radiations and so free, from all hazards, –, It can obtain images in any plane unlike CT, scanning which is more or less restricted to, crosssectional imaging., l, NMRtechnique is also useful in the study of tissue, metabolism by spectroscopy. Instead of using
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 666, , ŕďőĽę– ĐĽŐńŐĹť, , hydrogen nuclei, other nuclei of carbon, phosphorus, and sodium can also be used to understand, metabolic activities at the tissue level., Endoscopy, Endoscopy is a technique which enables a doctor, to view directly and/or indirectly the body parts, like bronchus, stomach, colon, urinary bladder etc., Using an endoscope a surgeon is able to carry out, minor operations without cutting through overlying, tissues., Endoscopes are named after the part of the body, they are designed to view. For instance a, gastroscope is used to examine the stomach for, an ulcer, a laparoscope to detect cysts or infections, of uterus, fallopian tube and ovaries, and so on., , Therapeutic instruments, Pacemaker, l, Pace maker is an electric device, first developed by, Greatbach and Chardack (1960)., l, A pacemaker has a pulse generator having long, lasting lithium halide cells., l, It is a device implanted in the heart of patients so, that the heart beat is generated by them. Therefore,, its function is to pace the heart on a long term, basis., l, Pacemaker is used when the heart beat drops to, about 30 to 40 per minute due to any reason. So, it is a life saving device., l, Pacemaker may be of various types external, pacemaker (worn on belt), epicardial pacemaker,, endocardial pacemaker, permanent pacemaker etc., l, Anyone fitted with a pacemaker should avoid, powerful radio or radar transmitters and, should not pass through security screens at, airports., l, An artificial pacemaker (introduced by Chardack,, 1960) is implanted when a person’s sinuatrial, node is not functioning properly., l, Demand pacemaker discharges impulses only when, the heartrate slows or a beat is missed. A normal, heartrate and beat suppresses the pacemaker., Medical lasers, l, Laser is a beam of very high energy particles., l, Laser is an acronym for light amplification by, stimulated emission of radiation., l, Lasers are also used for sealing of bleeding arteries, , l, l, l, , l, , in peptic ulcers, the destruction of abnormal cells, in various parts of the body such as the cervix and, treatment of endometriosis., Gall bladder stone and kidney stones can be treated, (by making it into fine powder) by using laser., Laser is also used in breaking of chromosomes at, specific points for genetic engineering., Depending upon the source of elements or, compound used, different types of lasers can be, generated like arson laser, neon laser and carbon, dioxide laser., By using a technique called laser photo bleaching, technique, the fate of a hormone bound to the, specific receptor on the cell surface can be known., , Intraaortic balloon pump, l, Intraaortic is meant for improving blood supply, to heart walls and other organs., l, A small balloon is positioned in the descending, thoracic aorta. It is connected to an external machine, which can inflate (with helium) and deflate it, rhythmically., l, The intraaortic balloon is inflated during diastole, or relaxation phase of ventricle. This pushes some, blood into coronary arteries. The balloon is deflated, during systole. The process is continued for hours/, days till normal functioning of the organ is restored., Angioplasty, l, Angioplasty is a technique of opening a blocked, coronary artery through ballooning. The process is, called percutaneous transluminal coronary, angioplasty (PTCA)., l, Coronary arterybypass surgery (CAS) is resorted, to when the main left coronary artery or threevessel, coronary artery is blocked., l, PTCA was first applied by Gruentzigin in 1977., l, PTCA literally means repairing of the coronary, artery (coronary angioplasty) by passing a catheter, through the skin (percutaneous) and reaching the, coronary artery via the lumen of the intervening, arteries (transluminal)., l, A deflated dilation catheter and a guiding catheter, are advanced over a guide wire into the blocked, segment of coronary artery., l, The balloon is inflated with several atmospheres of, pressure for 3040 sec for two or more times till, the blockage is removed. The same is confirmed, through coronary angiography.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚęĽĘďń– ♀ĚĘĺňŐńŐĹĽĚř–, l, , l, , Angiography is special Xray procedure that takes, pictures of blood vessels. It is usually done by, inserting a catheter into an artery or vein in groin., It is radiography in which a radioopaque contrast, medium or fluoroscopic chemical is passed through, catheter into the various parts of the heart to study, health of walls, valves, atria, ventricles, coronary, arteries, etc., For study of coronary arteries (coronary, angiography), the chemical is injected directly into, each coronary artery orifice and filming the progress, of chemical 3060 times per second., , l, l, , l, , Devices, Implants, l, Implants are devices used for replacing a diseased, organs or tissue within the body., l, Artificial heart valves may be either mechanical, or made of human or animal tissues., l, Mechanical valves are made of special, biocompatible plastics, metal alloys and ceramics,, having ball/disc occluder. Mechanical valves, develop tendency of blood coagulation. Hence,, blood anticoagulants are required., l, Tissue valves are obtained directly from pigs,, cadavers, (corpses) or made from pericardium of, animals. The valves have the tendency to calcify, with time, especially in young., l, Artificial arteries or vascular grafts are pliable, tubes generally made of fibrous plastic of dacron, (terylene) or teflon (polytetra fluoro ethylene)., Disposables, l, Disposables are devices used only once and then, thrown away. They prevent spread of diseases, from one person to another. It includes syringes,, needle, blood bags, oxygenators, blood dialysers, etc., l, Blood bag is used in storing blood, separation, of components (through centrifugation) and, transfusion of blood., l, Disposable blood bags decrease chances of, spreading diseases. Substitute of blood is also, being found. Perfluorocarbon can function as, artificial blood., l, Oxygenator is used in openheart surgery to, oxygenate the blood passing through the heartlung, machine., l, The first open heart surgery was performed in 1953, , l, , l, l, l, , 667, , by the use of the technique called “heartlung, bypass”. In this technique, the heart and lung of the, patient are bypassed and their vital functions’ i.e.,, circulation and respiration are carried out by a, “heartlung machine”. The function of the heart is, carried out by a rollerpump and the oxygenation, of blood is done by an “oxygenator”., Oxygenator can be called as an artificial lung., Common types of oxygenators are bubble, oxygenator, film oxygenator, membrane, oxygenator and liquid liquid oxygenator., Bubble oxygenators are used for short term, operations whereas membrane oxygenators are, more suitable but damages RBCs in long term, operation for longer operations and for operation, of infants., The main function of kidney in the body is to remove, the metabolic wastes from the body in the form of, urine. If, due to some reasons, kidneys do not, function properly then the metabolic wastes are to, be eliminated from the body by artificial means., This is known as blood dialysis or artificial, kidney., Artificial kidney can do only the passive filtration, process., The function of an artificial kidney is based on, the physicial laws of diffusion and osmosis., Various components of an artificial kidney are –, –, A blood dialyser having the membrane and, a rinsing fluid., –, A pumping system to pump the blood into, the body., –, The heating equipment with thermostat., –, Dialysing fluid, having same constitution as, that of blood plasma but deficient in nitrogenous, waste products, phosphates and sulphates with, slight excess of glucose to make it isotonic., –, The oxygen supply system to supply oxygen, to the blood., –, An arrangement to prevent the clotting of, blood (heparin and antiheparin)., , Prosthesis, l, External prosthesis are devices that are attached to, our body externally like an externally arm, leg or, denture (artificial teeth) so they help the body to, function normally., l, A myoelectric arm has also been developed which, can move prosthetic wrist and fingers to hold objects.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 668, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , Great achievement in this field have been, obtained by Dr. P.K. Sethi of Jaipur, India who, has evolved a prosthesis foot very similar to the, natural foot. It is very light in weight and can be, moved in all directions with great ease., Even a “denture” can also be regarded as an external, prosthesis as it remains in the mouth and not strictly, within the body., , Biotechnology applications, l, , Biotechnology (technology involving living beings, or their products for formation of useful materials), is being increasingly used in reconstructive surgery,, early diagnosis of various diseases, treatment of, hormonal, metabolic and genetic disorders etc., , Diagnostic kits, l, The kits are based on recombinant DNA and, immunological tests involving specific antibodies, for different antigens. For examples, malaria can, be tested even without seeing parasite in RBC, through precipitation of specific antibodies., l, Other tests available with the help of kits are, hepatitis, pregnancy, allergies, blood sugar, blood, urea and other biochemicals, urine tests, test of, cerebrospinal fluid, etc. In some cases colour, reactions are used for the tests., Cryopreservation of tissues and organs, l, This involves the use of natural tissues taken from, humans and other animals of the reconstructive, surgery., l, In this technique, cornea transplantation has been, done with great success. It is because of the fact, that cornea is not difficult to preserve, it also does, not link up with the blood supply and the immune, system of the recipient and the donor is also not, complicated., l, However, the preservation of other organs like, kidney, liver and heart is very complicated and may, evoke immune rejection., l, In case of skin transplant or graft, patient’s own, skin can be from an undamaged part (autograft), or may be taken from another organism of the same, species (allograft) or of another species, (heterograft). In allografts or heterografts, there, are more chances of skin rejection by the recipient, because of high immunogenicity property of the, skin. For this purpose the skin removed is subjected, to special treatment to neutralise immune specific, , proteins and then cryopreserved for emergency use., This can later be used at any time. However, it, should be noted that these transplants are not, permanent., Hormones and enzymes by recombinant DNA, technology, l, Discrete genes, mRNAs, proteins, hormones and, enzymes can be obtained in sufficient quantity, through rDNA technology for treating different, diseases., l, Plasmids carrying DNA sequences for A and B, insulin chains have been successfully introduced, in Escherichia coli for production of humulin, (human insulin). Gene for human growth hormone, cDIVA has been integrated with ‘trp’ gene of, plasmid to form the biochemical., l, Cultured leucocytes/lymphocytes/fibroblasts can be, used to produce interferons., l, Plasminogen activator produce enzyme plasmin in, the blood plasma to dissolve clots inside the arteries., Gene therapy involves introducing genes through, specific vectors like disabled viruses to overcome, genetic deficiency., [For more on biotechnology application refer, chapter Biotechnology and Genetic engineering], , Diagnostic laboratory test, l, , l, l, , l, , Laboratory tests are tools helpful in evaluating the, health status of an individual., The basic test is a screening test of blood and, urine., The tests are carried out for the following reasons –, –, Presence, excess or deficiency of various, biochemicals for knowing the state of, metabolism., –, Diagnose a disease (like anaemia, leukemia,, bleeding disorders, neutropenias etc), –, Confirm an early diagnosis., –, To know the stage of the disease., –, To screen individuals for diseases which are, yet to show their symptoms., –, For prognosis or forecasting sequence of, events of a disease., There are several types of test – haematology,, immunology, biochemistry, microbiology and the, emerging area of molecular diagnostics.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚęĽĘďń– ♀ĚĘĺňŐńŐĹĽĚř–, , 669, , Table : Blood test with their applications, Medical applications, , Blood tests, , l, , l, l, , l, l, , 1., , Total Leucocyte Count (TLC), , Increased leucocyte count (leucocytosis) occurs during Burns,, Haemorrhage, Leukemia and acute infections such as, Appendicitis, Pneumonia, Tonsillitis, Ulcers, Diphtheria, etc., Decreased leucocyte count (leucopenia) occurs during, Typhoid, Measles, Influenza, Liver cirrhosis, Dengue, Hepa, titis, etc., , 2., , Differential Leucocyte Count (DLC), , DLC is important to diagnose the type of infection., For example—(i) Neutrophils rise in neutrophilia;, (ii) Eosinophils rise in allergies; (iii) Basophils increase in, Leukemia; (iv) Lymphocytes increase in chronic infections;, (v) Monocytes increase in chronic inflammatory conditions., , 3., , Erythrocyte Sedimentation Rate (ESR) Increased ESR is observed during Pregnancy, Rheumatoid, Arthritis, Tumor formation, Chronic infections and in Tu, berculosis., , 4., , Lipid profile, (Estimation of cholesterol), , Evaluation of risk of heart disease. Increased levels of, serum cholesterol is observed during atherosclerosis, (hardening of blood vessels), Nephrosis (a disease of kidney),, Diabetes, Jaundice and Myxoedema. A decreased level of, cholesterol is observed during hyperthyroidism, nutritional, malabsorption and anaemia., , 5., , Haemoglobin Estimation, , Deficiency in haemoglobin is called anaemia., , 6., , Blood Sugar Estimation, , Level of blood sugar is increased in diabetes mellitus., , 7., , Blood Urea Estimation, , Increase in blood urea occurs with loss of body fluids and, Renal failure. Blood urea is decreased under normal preg, nancy., , 8., , ELISA Test, (Enzyme linked immunosorbent Assay), , Used for the diagnosis of Hepatitis, AIDS (caused by HIV),, thyroid disorder, and sexually transmitted diseases., , 9., , Widal Test, , Applied for the detection of typhoid., , Haematology is the study of blood formation and, the diseases which occur when the process goes, wrong., Routine blood test is also called as the complete, blood count or CBC., Blood tests are laboratory tests done on blood to, gain an appreciation of disease states and the, function of organs., Blood for laboratory tests can be capillary or, venous blood., Capillary blood is obtained from the tip of a, finger while venous blood from the upper part of, the arm., , l, , l, , l, , l, , Blood obtained is to be mixed with the, anticoagulants which could be oxalates, EDTA, or, heparin. EDTA is the most abundant used, anticoagulant., The haematocrit (Ht) or packed cell volume, (PCV) is the proportion of blood volume that is, occupied by red blood cells., The length of the tube containing blood cells,, divided by the length containing cells or plasma, gives the PCV., The packed cell volume can be determined by, centrifuging the blood in a capillary tube (a, haematocrit tube), which forces the cells to one end.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 670, , l, l, l, , l, , l, , l, , l, , l, , l, l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , A significant drop in the value of PCV means, anaemia while a higher value means polycythemia., The number of RBC/ L gives an indirect estimate, of the haemoglobin content of blood., Amount of haemoglobin per 100 ml of blood is, called haemoglobin count and is measured by an, instrument called haemometer., The mean corpuscular volume (or MCV) is a, measure of the average red blood cell volume that, is reported as part of a standard complete blood, count., In patients with anaemia, it is the MCV, measurement that allows classification as either, a microcytic anaemia (MCV below normal range), or macrocytic anaemia (MCV above normal, range)., MCV can be calculated by multiplying the, haematocrit percentage by ten, and dividing the, product by the RBC (red blood cell) count. The, result is typically reported in femtoliters., Haemoglobin concentration can be estimated by, the oxyhaemoglobin method, cyanmethaemoglobin, method, by specific gravity method or by chemical, method., TLC gives the total leucocyte count per cubic, millimetre of blood. The counting is done by, hemocytometer also called counting chamber., Increased TLC means leucocytosis while, abnormal low count means leukopenia., Normal value of TLC, Adults, – 7.5 ± 3.5 × 103/mm3;, New born, – 18 ± 8 × 103/mm3;, Full term pregnant woman – 15 ± 3 × 103/mm3;, Infant (1 year), – 12 ± 6 × 103/mm3;, Children (47 years), – 11 ± 5 × 103/mm3;, Children (812 years), – 9 ± 4.5 × 103/mm3;, It is, therefore clear that TLC value slowly declines, from birth to adulthood., DLC (Differential leucocyte count) gives the, percentage of different types of leucocytes., A change in the percentage of a specific leucocyte, indicates a specific disorder or disease. For example,, high neutrophil count indicates bacterial infection, while high eosinophil count indicates allergic, reaction., The erythrocyte sedimentation rate (ESR), also, called a sedimentation rate is a nonspecific, measure of inflammation that is commonly used as, a medical screening test., , l, , l, l, , l, , l, , l, , l, l, l, , l, l, , l, , l, , l, , ESR is the rate of sedimentation of RBC’s in a, given period of time. It helps in differentiating, between the degenerative disease and functional, disease., It is most commonly done by westergren pepette, or wintrobe tube., Factors like anaemia, increased level of fibrinogen,, globulins and cholesterol increase ESR while, removal of fibrinogen, increased albumin and sickle, shaped RBC decrease ESR., Lipid profile of blood is done on blood plasma., Generally it measures total cholesterol, HDL, cholesterol and triglycerides., Value of serum cholesterol, Normal value. 150250 mg/dl. Increase with age, and pregnancy are to be taken into consideration., The value is lower in neonates, infants and children., Value of HDL cholesterol, Normal value. (i) Men. 3555 gm/dl, average 44, mg/dl (ii) Women. 4564 mg/100 ml, average 55, mg/dl., Value of LDL, Normal value. 62185 mg/dl. Average. 150 mg/dl., Normal value of serum triglyceride is 80150 mg/, dl, Increase in glucose level is called hyperglycaemia, while decrease in glucose level in blood is called, hypoglycaemia., Blood glucose level increases in diabetes mellitus, and stress and decreases in Addison’s disease., Normal values of sugar., – Whole blood sugar (Fasting) 90 120 mg/100, ml. It includes 20 30 mg/dl nonglucose, saccharoid fraction., – Plasma/Serum Sugar (Fasting) : 70 110 mg/dl., – Plasma/Sugar Post Prandial Sugar :, 100 140 mg/dl., – Whole Blood Post Prandial Sugar : 140 180 mg/dl., Blood urea level may vary with the protein intake, of individual. It may increase during kidney disease, and decrease during liver failure., Concentration of blood urea indicates the health of, excretory system. There are two methods for, estimating the same – Nessler’s reaction and, Berthelot’s reaction. In both cases, urea is broken, down by enzyme urease to liberate ammonia., Nessler reagent is aqueous solution of 5%, potassium iodide, 2.5% mercuric chloride and 16%, potassium hydroxide. In Berthelot’s reaction,
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐŇĚęĽĘďń– ♀ĚĘĺňŐńŐĹĽĚř, , l, l, , l, , ammonia reacts with phenol and hypochlorite to, produce bluecoloured indophenol., Normal value blood urea is 3040 mg/dl., ELISA test (enzymelinked immunosorbent assay, test) is based on the detection of specific antigens, or antibodies of patient’s blood with the help of, enzymelinked antibodies or antigens respectively, in the ELISA wells of a polystyrene or polyvinyl, chloride microtitre plate., ELISA is very quick diagnostic technique for, detection of a wide variety of pathogens, disorders,, , l, , l, , 671, , allergens and hormones, e.g., (i) Pregnancy test, through presence of human chorionic gonadotropin, in urine or blood. (ii) AIDS or HIV infection., (iii) Hepatitis. (iv) STD or sexually transmitted, disease. (v) Rubella virus. (vi) Thyroid disorder., Widal test helps to diagnose typhoid or enteric, fever. A positive test indicates the presence of, gram negative bacteria Salmonella found in the, human intestine., A urinalysis (or “UA”) is an array of tests, performed on urine., , Biopsy, A biopsy is a small sample of tissue taken for microscopic examination so that the nature of a disease process, can be accurately determined. The word ‘biopsy’ literally means ‘taking a look at life’., Biopsy is a valuable and accurate way of finding out exactly what is wrong with a person and by, establishing an important diagnosis at an early stage, it is often lifesaving. Biopsies, especially from the, skin, may often be taken after a simple injection of local anaesthetic, the skin opening then being closed, with one or two stitches., Types of biopsies –, – Excisional biopsy : The entire lump or tumor is removed (excised)., – Incisional biopsy : A portion of the lump is removed surgically. This type of biopsy is most commonly, used for tumors of the skin to distinguish benign conditions and diagnose cancers and other tumors. This, can be done by ‘shave’, ‘curette’ or ‘punch’ methods., – Fine needle aspiration: A needle no wider than that typically used to give injections is inserted into, a lump (tumor), and a few cells are drawn up (aspirated) into a syringe.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 672, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 74, , Domestication &, Improvement of Animals, l, , l, , l, , l, , l, , Domestication of animals started during the, “hunting and gathering phase” of human, civilization. When man realised the utility of, domestic animal, he began improving them by, selective breeding., Animal husbandry is the science of rearing,, feeding, caring, breeding improvement and, utilization of domesticated animals., One the earliest animals to be domesticated was, dog. Dogs are represented in Egyptian monuments, as far back as 3400 BC and various breeds of dogs, existed during the height of the roman civilization., The cattle (cows, buffaloes and goat) were, domesticated during the New Stone Age in both, Europe and Asia. These provide milk to be taken, as such or in the form of butter, curd and ghee., Domestication perhaps began when these animals, were used as draft animals, probably in the first, steps of the tillage of the soil. As civilization, developed, feed became more abundant, methods, of caring for livestock improved, and the latent, possibilities for rapid growth, fat storage, and milk, production began to be realised under man’s, selection., , LIVESTOCK, l, , Livestock are those domesticated animals, or farm, animals who are kept for use or profit. On the basis, of the utility the livestock can be put into the, following categories –, –, Milk giving animals – Cows, buffaloes and, goats provide us with milk which provide, animal protein and serve as a perfect natural, diet. Milk is also used in preparing curd, butter,, ghee, cheese etc., –, Meat and egg giving animals – A large, , l, , number of animals such as sheep, goat, pigs,, ducks and fowls provide us meat and eggs., –, Animals utilized as motive power –, Buffaloes, horses, donkeys, bullocks, camels, and elephants are used in transport and, ploughing the fields., –, Wool giving animals – Sheep are reared for, obtaining wool from their hide., –, Miscellaneous uses – The hides of cattle are, used for making a variety of leather goods., Horns of animals and feathers of birds are, used for making a variety of goods and articles, of decoration. India is the largest exporter of, hides and skin in the world. Dung is used for, maintaining the soil fertility and also as fuel., The most important livestocks of India are cattle, and buffaloes which yield milk and help in, agriculture., , Zebu cattle or cow, l, , l, l, , l, , Cow (Bos indicus) is raised for milk. Bullocks, have been used in agricultural operations and, drawing carts. Hides are used for preparing leather, goods. Droppings yield gas and manure. Meat, bone, metal, glue and gelatin are other articles., A cow produces 8 – 10 calves during its, reproductive period., Breeding is of two types : natural and artificial., Natural breeding can be random or controlled (=, selective). Artificial breeding is through artificial, insemination. It involves introduction of semen of, selected bull artificially when the cow is in heat., The method is superior because –, –, It prevents spread of infection., –, The bull is not required at the time of heat., –, Exotic superior quality bulls can be kept far, away in environment suitable for them.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 673, , ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř, , –, –, , A single bull can inseminate a large number, of females., Superovulation (more ova and hence more, embryos), embryo transplantation and, surrogate mothers also help improve, breeds. Deep freezing (–190°C) is used for, keeping seven day old embryos for several, years. They can be transplanted when, required., , Exotic breeds are foreign breeds of animals, which are introduced in a country and require, special environment, e.g., Friesian, Holstein,, Brown Swiss, Jersey. They have been hybridized, with Indian cows to develop locally acclimatized, high performance cattle, e.g., Karanswiss,, Sunandini, JerseySindhi, Brown SwissSahiwal,, AyreshireSahiwal., ataka, , Buffalo, (Water buffalo, Indian buffalo, Bubalus bubalus =, Bos bubalus), l, Buffalo population in India is about 83.5 million, (1992 census). It is raised for milk. Buffalo bull, is used for agricultural operations and driving carts., Number of buffaloes is one third of cows but their, milk yield and hardness is better., l, Buffalo is better than cow in many respects –, –, The average annual milk yield of a buffalo is, 491 litres as against 173 litres of a cow in, India., –, Buffalo’s milk has about 50% more fat content, than cow’s milk., –, Buffalo milk also has higher mineral contents, than cow’s milk., –, Buffalo has better adaptability and disease, resistance., –, Buffalo lives longer than cow., –, The buffalobullock is an animal of strength., It moves slowly but can draw very heavy loads, over long distances., l, Breeding season of buffalo extends from September, to February. Average lactation period for a milch, buffalo is about 281 days. Buffalo has lower heat, tolerance than a cow., l, Infertility in local breeds of cattle has been, overcome through the use of pregnant mare serum, gonadotropin. Sterile and immature cows can be, induced to lactate through stilbesterol., , Table : Breeds of buffaloes, , Nili and Ravi, , Punjab,, , Sheep, l, , l, , l, , l, , l, , Sheeps (Ovis aries) are reared for wool and, mutton, mostly in hilly tracts. Sheep graze on grass, and herbs. Farm waste, mineral mixture, oil cake, and other cattle feeds can also be given., Deccani and nellore breeds are raised only for, mutton. Patanwadi provides wool for army, hosiery while narwari yields coarse wool., Four breeds yields good wool : Rampur Bushair, (brown fleece for superior cloth), lohi (quality wool,, also milk), bakharwal (undercoat for shawls) and, nali (carpet wool)., Exotic breeds include merino, dorset horn, and, suffolk correidale. They have been crossed with, Indian breeds to improve the quality of the latter., Advantages of sheep farming : Sheep farming is, more economical than raising other kinds of, livestock., –, A simple open pen with a fence of dried, thorny
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 674, , –, –, –, –, –, –, –, –, , ŕďőĽę– ĐĽŐńŐĹť, , babul branches is enough for keeping sheep., Expensive sheds are not required., Sheep do not need special care and facilities., Establishing of the foundation stock of sheep, is cheap and the flock swells up rapidly., Sheep can thrive on natural grasses, weeds, and farm wastes., Sheep give 4 products : milk, wool, skin and, lambs., Sheep do not damage trees unlike goats., Sheep are excellent weed destroyers., Sheep droppings form excellent manure., Mutton eating is not forbidden in any, community.Thus,there is a great scope for, raising mutton producing sheep., , –, –, , l, , The fat obtained is used for soap manufacture., Pig droppings are a good source of nitrogen,, phosphorus and potassium for agriculture., –, Ham, bacon and sausages are prepared from, pig meat., Pig is harmful too. Pork may contain encysted larvae, of the tapeworm Taenia solium. Therefore, pork, should be well cooked to avoid tapeworm infection., Table : Important breeds of pigs, Native pigs, Desi, , Uttar Pradesh, Bihar,, Punjab, Madhya Pradesh, , Ghori, , Mani pur, Assam,, Meghalaya, Arunachal, Pradesh, , Goat, l, , l, l, l, , Goat (Capra capra = C. hircus) is called poor, man’s cow because it yields a small quantity of, milk. However,the milk carries protein, lectoperoxide (LP) which is effective against a, number of disease causing bacteria., Goat feeds on a variety of wild plants, even prickly, ones., Goat also yields meat, skin and pashmina in case, of Kashmiri goats., Common breeds of goats are – malabari (Kerala),, berari (Maharashtra), bengal (Bihar, Orissa),, marwari (Rajasthan) , beetal (Punjab), jamunapuri, (U.P., M.P.), gaddi and chamba (Himachal Pradesh),, and kashmiri and pashmina (Himachal Pradesh,, Kashmir and Tibet)., , Exotic pigs, Berkshire, U.K., Large white Yorkshire U.K., Landrace, Switzerland, Denmark., , Horse, l, , l, l, , Pigs, l, l, , l, , l, , In India, pigs (Sus scrofa) raising and pork, production are in a primitive state., Pig (also called hog or swine) rearing is almost, entirely in the hands of poor people with little, resources, who continue to follow old and primitive, methods., The common village pig in India, is a scrub animal, and has no definite characteristics. It is a slow, grower and the pork is of poor quality. It is small, sized and produces small litters., Uses of pig, –, Pig meat is called pork. It is inexpensive and, is taken by the poor., –, Hide of the pig is used as leather and its bristles, for making brushes., , Horses are intelligent and are known for their, robust common sense. For thousands of years, horses have been used to carry man on their back,, pulled the carts and chariots both in peace and war., The horses are fast learners and loyal friends., They adopt themselves to all kinds of climates., They are used by the armed forces and police and, are used for transport at high altitudes. They are, used for riding, race and polo., , 1., 2., 3., 4., 5., 6., l, , l, , Table : Important breeds of Indian horse, Name, Regions, Kathiawari, Rajasthan and Gujarat, Marwari, Rajasthan, Bhutia, Punjab and Bhutan, Manipuri, Northeastern mountains, Spiti, Himachal pradesh, Zanshari, Ladakh, , Horses should be kept in hygenic and comfortable, stables. Stables should be able to provide sufficient, protection from inclement weather, excessive heat,, cold and rain. Cool places with good ventilation, are preferable to warm, close stables., Horses, as compared to other animals, have a low
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř, , reproductive rate. They are more difficult to, breed and have a long gestation period. Horse, breeding by controlled natural mating has been in, practice for long time in our country., , Donkeys, l, , l, , l, , l, , l, , l, , Donkeys are smaller than horses but have larger, head, longer pinnae and narrower hoofs. There, mane is erect and tail has a tuft of hair at the tip., Donkey is the most simple and unselfish animal., It can withstand adverse weather conditions. It is, a hardy animal and can work incessantly (continual), without rest on poor forage., Donkeys are used for riding and transport , mainly, of clothes, earth, bricks, etc. They are also employed, for pulling carts in some regions., There are two breeds of donkeys in our country :, small, dark grey; and large, light grey to almost, white. The grey donkey occurs in most parts of the, country. The white donkey, also called wild ass,, occurs in Rann of Kutch., Donkeys have descended from the wild ass Equus, asinus of Abyssinia. They were domesticated around, 4,000 B. C. in Mesopotamia and Egypt., The donkeys are generally bred at the age of 2.5, to 3 years. They can breed throughout the year,, there being no particular breeding season., The gestation period is 11.5 to 12 months. The, optimum time for mating is the third day of heat., Usually one young is born at a time., , Camels, l, , l, , l, , l, , Mules, l, l, l, , l, , A mule is a hybrid of a male donkey and a female, horse., The hybrid from a reciprocal cross is called hinny., Mules show hybrid vigour. They are sturdier than, the horse and larger than the donkeys. Both male, and female mules are infertile., Indian army has imported male donkeys from, Europe for breeding mules. Army uses two types, of mules : (i) general service type, and (ii) mountain, artillery type. The latter are firm footed and can, carry heavy loads on steep terrain., , Elephant, l, l, , Elephant is the largest land animal. It was used in, war, for religious purposes and in royal processions., It is regarded in India as a remover of obstacles and, a symbol of good fortune., , 675, , Camel has been aptly described as the ship of the, desert. It is the valuable beast of burden and, transport in the hot and arid desert regions., There are two species of camels. The Bactrian, camel is an inhabitant of Central Asia. It has two, humps. The second is Arabian or Dromedary camel, with one hump. In India, only the onehumped, camels are found. The Arabian camels is less heavily, built and longer in the hind. Its skin is soft and, comparatively thin., Adaptations for desert life –, –, Extraordinary power to resist thirst and hunger., –, It can live on thorny shrubs., –, Long neck and thick foot pads for movement, on loose hot sands., –, Thick skin over the body to prevent water, loss., –, Long eye lashes to prevent the eyes from sand., –, Hard lips to browse thorny bushes., –, Hump acts as an emergency foodstore in, the form of fatty tissues to enable it to live, under drought conditions., Camel is used for riding, carrying loads, ploughing, and threshing grains. It is also used for pulling, carts, drawing water from wells. It is used as a, motive power in surgarcane and oil seed crushing, mills. Hair of camel are used for making garments,, brushes and cords. Its dung is used as fuel. Hide, provides leather for making saddles. Camel’s milk, and meat are taken by the desert dwellers., , POULTRY, l, , l, , l, , Poultry is a rearing of domesticated fowls, (chicken), ducks, geese, turkeys, guinea fowls and, pigeons, but it is more often used for fowls., Keeping fowls for eggs, raising browlers (table, birds) for meat, poultrybreeding and hatcheries, are the common poultry enterprises. Other allied, professions are egg and meat processing, egg and, poultry marketing processing and sale of food, poultry equipment., Poultry farming has now become popular, and many, of the farms have several thousands layers. The, factors favourable for the growth of poultry, farming are : small initial investment, quick return,, requirement of small area and use of various kinds, of food stuffs.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 676, , l, l, , l, l, , l, , l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť–, , Domestic fowl (Gallus domesticus) constitutes the, major poultry bird., Poultry birds exclusively grown for meat are called, broilers (eg. plymouth rock), layers are for egg, production, cockerel are young male fowls and, rooster are mature male fowls., Pullet is young hen of less than one year., Broilers are generally quick growing birds which, are generally males but can also be female. They, are grown for 810 weeks when they attain a weight, of 1.52.0 kg. Broilers are sold in fresh or frozen, form after dressing (removal of feathers, head and, feet)., Layers are females which have a high rate of egg, production. They are debeaked twice (21st day, and after 4 months). Debeaking is removal of tip, of beak. It reduces chances of injury when birds, fight amongst themselves. Birds are given fresh, balanced diet everytime. Extra care is required for, young birds. It is called brooding period. It lasts, for 68 weeks. Dubbing is removal of wettles and, combs of young birds. Females start laying eggs in, about 22 weeks. It continues for 1215 months., When egg production becomes uneconomical, the, layers are sold for slaughtering., Breeds of fowls are –, –, Indigenous breeds (desi breed) : Chittagong,, Punjab brown, Aseel, Bursa, Danki,, Tellicherry, Karaknath etc. Aseel is one the, best table bird but it can not be raised on, commercial purpose because of its poor, growth and low fertility., –, American breeds : Polymouth Rock (most, popular breed of USA), wyandotte, Rhode, Island Red, New Hampshire., –, Asiatic breeds : Brahma, Langshan, Cochin., –, English breeds : Sussex, Orpington,, Australorp, Cornish, Dorking, Red cap., –, Mediterranean breeds : Leghorn, Minorca,, Ancona, Spanish, Andalusian and Buttercup., The largest and the most healthy fowls are, Brahma, Australops, Orpington, Langshan, Sussex., Monarcha is the best layer of lange sized eggs., Aseel is one of the best table birds with plenty of, flavoured flesh., The desi birds (indigenous breeds) generally have, poor egg laying capacity., For poultry breeding two aspects are kept in mind, , l, , l, , l, , l, l, , (i) improving the birds for poultry meat, and (ii), improving the birds for more eggs. For meat fast, growing chickens are selected. When the production, of eggs is the prime consideration, the high egg, laying varieties of chickens are selected. The hens, with characters for high egg production give better, results., Cross breeding is done between the males and, females of desired characters. Cross breeding has, resulted in higher rate of hatching of eggs, more, efficient and faster gains in weight and lower rate, of chick mortality., Some of the important diseases of poultry are, given below :, –, Viral diseases, these are Fowl fox and Ranikhet, or New castle disease., –, Bacterial disease, these include fowl cholera,, salmonellosis and coryza., –, Fungal disease, Aspergillosis., –, Parasitic diseases, the parasites are of two, types – internal parasites (roundworms,, tapeworms and thread worms) and external, parasites (fowl mite, chickenmite, fleas, ticks,, lice, etc)., Ducks form only 6% of our country’s poultry, population. They are commonly raised in the, southern and eastern regions of the country., There are 20 breeds of ducks, the native ones, include Indian Runner and Syhlet meta, and the, exotic ones include Muscori, Pekin, Aylesbury and, Campbell. Domesticated ducks have been derived, from the wild duck named mallard (Anas boscas)., Brown and white geese (Anser) are common in India., Turkey (Meleagris) was domesticated in Mexico, in the 16th century. It is highly esteemed as a, table bird. It is associated with Christmas, festivities in U.K. and with those of Thanks giving, in U.S.A. The turkey breeds in demand at these, occasions include Narfold, British white, Broad, Beasted Bronze and Beltsville Small White., , FISHERIES, l, , Fisheries is a water body having fishes and other, aquatic animals which are reared and caught for, food which is rich in protein, vitamins A and D., Marine animals are also richer in iodine. Shark, liver oil and Cod liver oil are very good source of, vitamin A and D.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř–, l, , l, , Aquaculture is rearing and management of useful, aquatic plants and animals like fishes, oysters,, mussels, prawns, etc., Pisciculture is rearing, catching and management, of catching of fish., , l, , Types of fisheries, Fresh water fisheries or Inland fishery, l, They are small scale fisheries found inland. Inland, fisheries are of further two types– brackish water, and fresh water., l, Brackish water fisheries (estuarine fisheries), develop in lagoons, mangroves, estuaries, back, waters, etc. Prawn (Penaeus, Metapenaeus), Mullet, (Mugil), Perch (Lates), Chanos and Ladyfish, (Sillago) are some eg’s., l, Fresh water fisheries : India has a large area of, 16 million hectares under fresh water in the from, of rivers, canals, irrigation channels, reservoirs,, lakes, tanks, ponds and pools. Important products, of inland fisheries are fresh water prawns, (Palaeomon, Macrobrachium) and fish like Labeo, rohita (Rohu), Labeo calbasu (Calbasu), Catla catla, (Catla), Wallago altu (Malli), Clarias betrachus, (Magar), Msytus singhala (Singhara),, Heteropneustes heteropneustes (singhi)., l, Capture and culture fisheries are two types of, inland fisheries., l, Capture fishery is practice of only catching the, fish available naturally as in large water bodies of, lakes, reservoirs, tanks, etc. Marine fisheries are, also capture fisheries., l, Culture fisheries is the type of fishery found in, small water bodies where fish is first reared and, then harvested. Culture fishery of three types –, –, Monoculture : Growing of only one type of, fish, eg. cat fish., –, Polyculture : Growing of two or more types, of fish in the same water body, e.g., Tilapsia, and Carp., –, Composite culture : It is rearing of food fish, and other food animals in the same water, because they do not harm one another but, reside and feed at different levels like surface,, middle and bottom., Marine fishery, l, Marine fishery deals with the fishery aspects of the, sea water or ocean. Some of the important marine, , 677, , fishes are – Hilsa (Hilsa), Aluitheronema (Salmon),, Sardinella (Sardine), Harpodon (Bombay duck),, Stomateus (Pomphret)., Crustacean fisheries constitute the most, important class of marine fisheries of the country., They include prawns, lobsters and the crabs. Indian, prawn industry constitutes 18 per cent of the world, production. The annual catch is about one lakh, tonnes and is second only to the U.S.A. Prawn, pulp is exported to several countries., , Molluscan fishery, l, The commercial culture of molluscs such as edible, oysters and mussels had been old practice in, European countries and Japan., l, The bivalves, gastropods and cephalopods are the, molluscs of economics importance. This group, constitutes a good percentage of sea food. Pearls, and shells are also very important articles of trade., , Fish farming, l, , l, , l, , l, , l, , Fish farming (pisciculture) aims at the cultivation, of selected varieties of fishes in ponds by providing, them suitable physicochemical and biological, conditions. Cultivation is done in a manner that a, maximum amount of fish is produced within a short, period of time, and in a limited amount of water., Various techniques of fish farmings have been, successfully developed in the country and may be, classified as – complete fish farming, restricted, fish farming, extensive fish farming, intensive fish, farming, depending on natural habitat of fish,, monoculture, polyculture, monosex culture and, integrated fish farming etc., Complete fish farming : This technique began, with the production of eggs and culminates in the, formation of full size fishes, which may be utilized, as food, for marketing or as breeding stocks. The, farm must therefore have the necessary types of, ponds and facilities required for feeding, breeding, and growth of fish., Restricted fish farming : This type of fish culture, is restricted to one or more stages of fish growth., Fish seeds, fry or fingerlings may be produced and, allowed to grow in the ponds of the farm. Hatcheries, may also be established where, after induced, spawning the collected fishes may be sold to, fisherman for restocking their ponds., Extensive fish farming : Here the fishes are
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 678, , l, , l, , l, , l, , l, l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , cultivated on the natural food available in the pond, and their productivity corresponds to natural, productivity., Intensive farming : This cultivation is based on, artificial feeding, so that the production is a, maximum quantity of fish in minimum quantity of, water. A semiintensive farming of fish is a, transitional phase between extensive and intensive, fish farming., Depending on natural habitat of fish : Fish, farming may be done in cold water, warm water,, fresh water or brackish water depending on the, habitat of the fish selected for cultivation., Monoculture : It is the culture of only a single, type of fish species in a pond. It may be Tilapsia, of one species or common carp or any other species., Polyculture : Here two or more species of fishes, are cultivated together in a pond, e.g. a mixture of, Chinese carp, grass carp and big head carps are, cultured together. It is also sometimes called, composite culture., Mono sex culture : It is the culture of only one sex, of a species of fish in a pond., Integrated fish farming : In this type of fish, farming, the culture of fish is done along with the, agricultural crops such as paddy and banana., Also fish culture may be carried out by placing the, fishes in a cage and suspending it in water, released, from the farmers house and animal shelter (cage, culture)., , By products of fishing industry, l, , l, , l, l, , Fish oil : It is extracted from adipose tissue of fish., It is a mixture of triglycerides, cholesterols,, alcohols, pigments, vitamins etc. Fish oil is grouped, into body oil and liver oil. Body oil is generally, used in lubricants, cosmetics, paints etc. Liver oil, is extracted from liver of fishes and is of, pharmaceutical value as it is main source of vitamins, A, C, D and E. Liver oil of hammer headed fish, and sharks has highest percentage of vitamin A., Fish meal : It is prepared from the wastes of fish, oil or from the whole fish. It is used as major food, of domestic animals like pigs, poultry etc., Fish flour : It is highly nutritive food for infants, of 3 to 4 months as it is easily digested., Fish roes : It is rich source of thymine, ichthulin,, creatine, tyrosine, xanthine, hypoxanthine, vitamin, , l, , l, , l, , l, l, , l, , l, , B, C, D and E etc. It is widely used because of its, easily digestibility and high nutritional value., Fish selage : It contains high percentage of, unaffected vitamins. It is semi solid material, prepared from fresh pieces of fish treated with, sulphuric acid, formic acid and molasses., Fish fertilizer : The wastes obtained during the, preparation of fish meal is widely used as manure, for coffee, tea and tobacco plantation. It is of 3, types :, –, Dry fish manure : Whale fish is dried in, sunlight and used as manure., –, Pit fish : It is obtained by burning the fish, waste into pits., –, Fish guana : The refuse of cooked fish body, obtained after proper pressing during the, extraction of oil is fish guana., Fish skin : The skin of some fishes like sharks and, rays are used for making jewel boxes, purses and, several other ornamental purposes., Fish glue : It is prepared from skin and bones of fishes., Chum : The residue obtained during extraction of, glue after proper drying is used as poultry feed or, fertilizer., Isinglass : It is produced from air bladder of cat, fishes and carps. It is used for preparation of purse,, book and ribbon etc., Squalene : It is a constituent of the unsaponifiable, fraction of fish oil. It is used as a mordant in the, dyeing of synthetic fibres., Induced Breeding, Induced breeding is a technique whereby ripe, fish breeders are stimulated by pituitary hormone, injection to breed in captivity. The stimulation, promotes a timely release of eggs and sperms, from ripe g onads. The hormone is the, gonadotropin playing a role in bringing about, spawning. A substitute of the pituitary hormone,, natural or synthetic may be equally effective and, is preferred for commercial usage because of the, difficulty of obtaining large quantities of pituitary, hormones for large scale usage, which in turn, would mean a larger number of fish donors. The, mammalian chorionic gonadotropin (CG),, synahorrin (combination of CG and pituitary, extract) and SZK (from pregnant mare serum), are some of the tested substitutes.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř, , SERICULTURE, l, , l, l, , l, l, , Sericulture is the breeding and management of, silkworm and the raw silk they produce. Depending, upon the number of crops of silkworm cocoons, raised per year., Sericulture is univoltine, bivoltine or multivoltine., Silk is a natural fibrous secretion which is secreted, by caterpillar over it during cocoon formation., Cocoons are dipped in hot water to kill the pupa, and separate the fibres., India ranks third in the production of silk., Karnataka ranks first in production of raw silk., Fine texture silk is the product of the domesticated, type or mulberryfeeding silkworms belonging to, the family Bombycidae, whereas silk of other, varieties Eri, Muga, Tasar, are products of the larvae, of wild or semi wild types of moths belonging to, the family Saturniidae., , Silk, l, , l, , l, , Silk is a natural fibrous substance obtained in the, form of a long, continuous filament from cocoons, (pupal nests) spun by a large variety of moth, caterpillars, known as silkworms. At the end of the, fifth or last stage in the growth and development, of these caterpillars, silk is exuded from the silk, glands present inside their body (i.e., located on, the ventrolateral sides of the body cavity, which, is extended from the 4th to the 8th segment of the, abdominal part of the body) through the spinneret, to spin the cocoons. Silk filaments from these, cocoons are reeled out after proper treatment into, raw silk, made of usually 810 filaments., Silk is tough and bright but at the same time it is, soft, light and elastic. The silk fibre never creates, any reaction on the skin and can be used in all, season. Hence silk, the most beautiful of all textile, fibre, is acclaimed as the queen of textiles., Silk is composed of two kinds of very large, molecular weighted amphoteric colloidal proteins, – fibroin and sericin. Fibroin (C15 H26 N5 O6), constitute about 75% and sericin (C15 H25 N5 O8), the remaining 25% of the silk thread., , Structure of silk gland, l, l, , Each gland is divided into three regions, viz., anterior, middle and posterior regions., The anterior sections of both the sides of the glands, , l, , l, , l, , 679, , are narrow and united near the mouth to form the, spinneret., The middle part is broad and is termed as reservoir, where as the posterior section is long, narrow and, coiled., The posterior region produces the inner core, (fibroin) and the middle part secretes three kinds, of sericin., A pair of Lyonet’s glands or De Filippis gland, is located near the spinneret. The secretion of, those glands mixes with the silk thread and, lubricates it., , Species of silkworm, Mulberry silkworm, l, Bombyx mori belongs to the family Bombycidae., China is the native place of this silkworm but it has, now been introduced in India, Japan, Korea, Russia, and France., l, The natural food of this worm is mulberry leaf., l, The silk produced by this moth is white or yellow, in colour, called mulberry silk., l, Mulberry specially grown for silkworm is called, moriculture., Tasar silkworm, l, Antheraea paphia belongs to the family Saturniidae, are common in India, China and Sri Lanka., l, The caterpillar feeds on ber, oak, sal and fig plants., The moths do not breed easily in captivity., l, The silk produced by them is called tasar silk., Muga silkworm, l, Antheraea assama also belonging to family, Saturniidae are semidomesticated in nature., l, The native place of this species is Assam., l, The caterpillars of this worm feed on Machilus, plant and the silk produced by this moth is known, as muga silk., Eri silkworm, l, Attacus ricinii belongs to the family Saturniidae., l, It feeds on castor leaf and cocoons cannot be reeled, but have to be spun., Oak silkworm, l, Antheraea pernyi produces good quality silk., Giant silkworm, l, Attacus attas belongs to family Saturniidae. It is, the largest of the living insects reaching upto, 11 inch in wing span.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 680, , ŕďőĽę– ĐĽŐńŐĹť, , Life history of mulberry silkworm, Silkworm is dioecious i.e., sexes are separate., Fertilization is internal, preceeded by copulation., l, Development includes complete metamorphosis., l, Life history of silkworm includes eggs, caterpillar,, or larva, pupa, imago., Eggs, l, After fertilization each female lays about 300500, eggs in clusters upon leaves of mulberry trees., l, The egg of Bombyx mori is a very small and hard, structure whose shell provides a protective covering, for embryonic development. Female covers the eggs, by a gelatinous secretion., l, After laying the eggs the female does not take food, and dies within 45 days., l, In India, and other tropical countries, the silkmoth, lays nondiapause eggs with continuous growth and, development, which enables to raise 2 to 7, generations within a year. In temperate (cold), countries, diapause eggs are laid which rest until, spring when growth is resumed, so that a single, generation is produced per year., Caterpillar or larva, l, The larva which hatches from egg in about 10 days, is known as caterpillar. During growth the larva, will moult 4 times., l, The period between successive moults is called an, instar. The I instar larva moves about in a, characteristic looping manner. Its head bears, mandibulate mouthparts with which it at once starts, feeding on mulberry leaves and grows very quickly., After 45 days it stops feeding and becomes inactive, after which moulting or ecdysis takes place. The, earlier skin bursts and a new caterpillar emerges, out. It starts eating voraciously and then moults, again. This process is repeated four times., l, A full grown V instar caterpillar has biting and, chewing mouthparts and 3 pairs of true legs. A pair, of salivary glands develop in the lateral sides of its, body., Pupa or chrysalis, l, Mature caterpillar stops feeding and returns to a, corner among the leaves. Its salivary glands now, secrete a sticky fluid through a narrow pore of the, spinneret situated on the hypopharynx (lower lip of, its mouth). This sticky substance turns into a fine,, long, solid thread of silk in contact with air. The, , l, , saliva is continuously poured out for three or four, days., l, Silk thread is composed of 5 filaments stuck, together by sericin secreted by two other glands. It, becomes wrapped around the body of caterpillar, forming a pupal case known as cocoon., l, The silkworm transforms inside cocoon into a, tubular pupa or chrysalis., Imago, l, Active metamorphic changes take place during, pupation. Unsegmented abdominal legs (prolegs), disappear. Thorax develops two pairs of wings. The, pupa finally metamorphosis into the imago. It, secretes an alkaline fluid to moisten one end of, cocoon and then escapes by forcing it way out of, the softened silk. After emergence the male and, female moths mate, lay eggs and die within 3 to 4, days., l, Life history of a silk moth illustrates a type of, complete metamorphosis (holometaboly) among, insects. Eggs of this moth hatch out into larvae, which differ greatly in appearance and food habits, from the adults., l, Silkworm seeds or eggs are usually of two kinds, – hibernating and nonhibernating., l, Hibernating or annuals eggs which are deposited, by the moth in spring, undergo a diapause, (aestivation during summer and autumn,, hibernation during winter) and hatch out only in, the next spring. Nonhibernating eggs are those, derived from successive generations without any, pause in a year., l, Laying of hibernating or nonhibernating eggs, depends upon the voltine character of the silkworm, race i.e., univoltine worms lay hibernating eggs, hence from them only one crop is taken in one, year. Multivoltine worms lay nonhibernating eggs., Some races are also bivoltine, trivoltine etc., depending upon the number of generations, produced in a year., l, Voltinism is a specific characteristic and is, hereditary but can be radically influenced by factors, like temperature, light, humidity, etc., l, Darkness favours laying of nonhibernating eggs., Light favours the deposition of hibernating eggs., Hibernating eggs are usually coloured bluish grey,, whereas non hibernating eggs are either pale yellow, or cream coloured.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř–, l, , Silk spinning activity of the silkworms is a, physiological function by which the larvae, probably get rid of excess of protein acquired from, the mulberry leaves during the period of their, growth., , Rearing of silkworm, It is the most important aspect of sericulture, requiring great skill, care and patience, constant, vigilance and cleanliness. In India, sericulture is a, subsidiary industry, carried on without much cost, of labour in different parts of the country., l, The most important appliances used for rearing, silkworms in India include bamboo trays, mounting, or spinning trays (chandrikas), nets for transferring, worms from one tray to another, knife or bonti for, cutting leaves into chips etc., l, Two methods of rearing silkworms practiced in, India are –, –, Cellular rearing which means rearing of, individual layings separately, and, –, Mass rearing meaning rearing of worms in, bulk for production of cocoons for reeling, purpose., Steps of rearing operations, l, Grainage management, –, The aim of the establishment of grainage is to, provide good quality of seed to rearers and, maintenance of original quality of races., Proper nutrition and protection from the attack, of diseases should be provided right from the, caterpillar stage., –, After final selection of good quality of “crop, of silkworm”, the cocoons are kept for mass, emergence., –, Males and females just after emergence have, to be separated. Female of one lot is kept with, the males of the other lot and copulation is, allowed., –, Fertilized females are subjected to egg laying., l, Egg laying, –, Within 24 hours the females complete egg, laying process after which they will die. The, eggs are called as seed and are kept in sterilized, trays and stored at 4°C under laboratory, conditions. One female may lay 400 to 500, eggs depending on the race., –, This commercial seed is supplied to the rearers., , l, , l, , l, , l, , l, , l, , l, , l, , 681, , Hatching, This is an important phase of sericulture industry, since as soon as the larvae are hatched they start, feeding voraciously. So sericulturists should be able, to supply sufficient amounts of fresh mulberry, leaves to the young hatched larvae., Supply of seed to rearers and commercial rearing, –, Next step involves the supply of seed or, caterpillars to the farmers., –, The old rearers well versed with the rearing, technique may purchase eggs for rearing but, new and untrained rearers should always be, given II instar caterpillars for this purpose., –, Fully grown fifth instar larva stops feeding., Spinning of coccons, –, This is the period when the caterpillar stops, feeding and starts secreting a pasty, substance from the silk gland., –, In this condition worms should be picked up, and transferred to the spinning trays and kept, in a position of slope to the sun for a short, period., –, Within three days spinning is over and the, cocoon is formed and this is the last phase of, the rearing of the silkworm., Post cocoon processing is the method of obtaining, silk thread from cocoon. This includes stifling and, reeling., Stifling is the process of killing the cocoons., Selected good sized cocoons are dropped into hot, water. The killing of the cocoon in boiling water, helps in softening the adhesion of the silk threads, among themselves and loosening of the outer, threads to separate freely, facilitating the unbinding, of silk threads., Reeling and spinning : The process of removing, the threads from the killed cocoon and combining, them together to make a thread of raw silk is called, reeling. 4 or 5 free ends of the threads of these, cocoons are passed through eyelets and guides to, twist into one thread and wound round a large wheel, from which it is transferred to spools. The silk, obtained on the spool is known as raw silk or, reeled silk. The waste outer layer or damaged, cocoons and threads are separated, teased and then, the filaments are spun. This silk is called as “spun, silk”., The raw silk is further boiled, stretched and purified
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 682, , ŕďőĽę– ĐĽŐńŐĹť, , –, , by acid or by fermentation and then carefully, washed over again and again to bring about the, well known lustre on the thread., , Diseases, l, , The common diseases of silkworm are –, –, Pebrine or pepper disease by protozoan, Nosema bombycis. Parasite infects eggs and, is, therefore, transmitted to next generation. It, kills caterpillars., –, Flacherie is an infectious viral disease marked, by body flaccidity and digestive disorders., –, Muscaridine is caused by a fungus, Spicaria, or Botrytis., –, Grasserie is caused by Borrelina virus, bombycis, , Economic Importance, l, l, l, , l, l, , Silk is the finest textile fibre which is known for, its softness, lustre and durability., It is mixed with other textile fibres to produce, terisilk and cotsilk., Because of its strength and durability, it is used in, the manufacture of parachutes, filter cloth, fishing, fibres, insulation coils, etc., It earns a lot of foreign exchange for India., It is cottage industry and can be undertaken by, villagers on a large scale., , APICULTURE, l, , l, , l, , Apiculture or bee keeping is care and management, of honey bees. Honey bees give us honey and wax., They are also good pollinators., Honey bees are these days raised in apiaries. Apiary, is the place where bees are cultured and bred to get, commercial products., Common breeds of honey bee are –, –, Apis dorsata (Rock bee) : Largest bee. Due to, its ferocious and irritable nature, specific hive, and migratory habit it is very difficult, rather, practically impossible to domesticate them for, bee keeping industry., –, Apis indica : Indian bee, commonly found in, forest & plain regions of India. This species, is very gentle in nature & so can be, domesticated easily., –, Apis florea : Little bee. Due to its docile nature, & rare stinging behaviour the combs can be, removed easily for the honey., , Apis mellifera : European bee. Due to its docile, nature they can be domesticated easily and, can be improved by breeding for several, hundred years. Out of its several variety, the, Italian variety is reared every where in Europe, & America in artificial hives for honey., , Honey bee, Honey bees are highly specialized insects, both in, structure and habits. Sense organs, mouthparts,, wings, legs and many internal organs are more, diversified and specialized than in cockroach or, grasshopper., l, They are social insects living in colonies and, exhibiting polymorphism and division of labour., l, The nests (or beehives) of honey bees, harbouring, thousands of individuals, are seen hanging down, the tree branches or ceilings of houses and old, buildings. These are built by their cooperative, efforts and manifest a spectacular engineering feat., l, Behive are formed of a secretion from the wax, glands of workers. It consists of two layers of, hexagonal chambers of cells. Some chambers are, packed with honey and pollen. They are called the, storage cells and are closed with a lid of wax. In, other chambers, young ones are brought up. These, are known as the brood cells. The latter are of, different sizes to accommodate different castes., l, Honey bees feed on pollen and nectar of flowers., They communicate with each other through a sign, language. Mating occurs in a nuptial flight and, development includes metamorphosis., l, Three types of individuals (castes) found in the, colony of honey bees are – queen, drones and, workers., Queen, l, Queen (25) is the only fertile female which lays, eggs continuously for 25 years., l, Normally one queen is found in one nest. It is 15, to 20 mm in length and can be easily distinguished, by her long tapering abdomen, short legs and wings., Structurally it is unable to produce wax or honey, and gather pollen nector., l, Egg laying is the only function of queen., Drones, l, Drones (45 days of life span or five weeks) are males, which mate with queen. Their number in the colony, is not much. The sting and wax gland are absent., , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 683, , ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř–, , Drones are smaller but stouter than queen with, broader abdomen, longer appendages and larger, wings., Workers, l, Workers (312 months) are sterile females and, performs various duties of the colony., l, The queens and drones are fed by the workers., l, The worker bees are darker and smallest members, of the colony. They have chewing and lapping type, of mouth parts, modified for collecting nectar and, pollen of the flowers., l, The abdomen contains the wax glands and the sting., l, Wax glands are the glandular area secreting wax, lies on the ventral surface of the last 4 visible, segments of abdomen. Wax is secreted through, minute pores in the form of flat scales. It is, masticated by the mandibles before its use for, building the “cells” of the honeycomb., l, Sting is the modified ovipositor of the insect, and is used for injecting poison for protection., It is composed of two straight grooved stylets, or lancets. Their distal free ends are provided, with many anteriorlypointed spines or barbs, which prevent the removal of sting. The muscles, associated with the sting help in the operation, of lancets. A set of 3 chitinous plates on either, side act as levers to move the barbs. A pair of, filiform po iso n g la nds secrete th e a cid ic, material that is stored in a saclike storage, poison sac located at the base of the sting., Associated with it is an elongated alkaline gland, that secretes an alkaline material. The two, materials mix to form the poison or been venom, that flows down the sting into the wound of the, victim. After stinging, the worker bee leaves, the sting apparatus and dies. Sting of queen bee, is longer but less barbed and can be withdrawn, without injury to her own body. Males do not, have a sting because they have a copulatory, apparatus instead of an ovipositor., l, The worker bees of a hive fall into three major, age groups or cases. These are–, –, Scavenger (or Sanitary) bees : For the first, three days each worker bee acts a scavenger., –, House (or Nurse) bees : From the fourth, day onwards, each worker been feeds like, a foster mother, with a mixture of honey, and pollen. From the seventh day, the, , maxillary glands of a worker bee secrete, “royal jelly” to feed young larvae, the queen, and those older larvae which are destinated, to develop into future queens. From the, twelfth to the eighteenth day, each worker, bee develops wax glands. Wax is secreted, in the form of thin scales., Foraging (or Field) Bees : When a worker, bee is about 15 days old, it takes up the job, of foraging. It means they explore new sources, of nectar and pollen and collect these and, water. These bees are also called scout bees., Worker bees live for a few weeks only., , l, , –, , Life history, l, , l, , l, l, , l, , When the colony becomes overcrowded, the old, queen leaves the hive along with some workers, and drones. They fly to a new place to establish, another colony. This is called swarming., Swarming takes place during the spring or early, summer. New queen is then formed in the old, colony. She soon undertakes a marriage, or nuptial, flight with the drones. Mating occurs in the air., Drones dies during the course of copulation. The, queen mates only once in a life time., The queen, after mating, returns to the hive, it stores, the sperms in its spermatheca, which suffice to, fertilize all the eggs laid by her and wards off the, drones after copulation. She does not leave again, till she becomes old when swarming occurs., Queen lays 2 types of eggs – fertilized [diploid, (32 chromosomes)] and unfertilized [haploid, (16 chromosomes)]., Queen lays, Unfertilized eggs (n), , Fertilized eggs (2n), , Natural, parthenogenesis, Larva fed on, (arrhenotoky), , Drone, , royal jelly, Queen, , l, l, , l, , Larvae fed, on honey, Worker, (sterile female), , The life cycle includes complete metamorphosis, or holometabolic development., Larvae emerge out from fertilized as well as, unfertilized eggs which are completely different in, external structure, many internal organs and mode, of living from adult., The drones are developed parthenogenetically
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 684, , l, , l, l, , l, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , (called arrhenotoky) from unfertilized egg,, whereas workers develop from fertilized eggs., The worker bees have a pollen collecting, apparatus, honey storing mechanism and wax, secreting glands. Queen from its mandibular glands, secrete a queen substance which inhibits the worker, bees from building the brood chamber for future, queen bees., Drones take 24 days to develop from egg to the, adult stage., Larvae from fertilized eggs if fed upon royal jelly,, develop into queen whereas if fed upon honey, develop, into workers. Thus workers are sterile females., The royal jelly consists of digested honey and pollen, mixed with glandular secretion into mouth of, workers. After 5 days of feeding the cell is sealed, and larvae undergo pupation., Queen takes about 15 days whereas workers take, about 21 days to complete their development., Life span of queen, drone and worker is 2 to 5, years, 57 days and 3 to 12 months respectively., , Communication, l, , l, l, , Ernest Spytzner (1788) was the first to draw, attention to the fact that bees communicate by means, of definite movements now called “bee dances”., Prof Karl von Frisch (1946 to 1969) got Nobel, Prize for decoding the language of “bee dances”., He discovered that scout bees perform two types, of dances for communication –, –, Round dance is performed when a newly, discovered food source is close (less than 75, metres) to the hive., –, Tail wagging dance is performed for long, distance food source (farther than 75 m)., , vitamins (B1, B6, C and D). Sugars include laevulose, (Lfructose, 41%), glucose (35%), sucrose (1.9%), and dextrin (1.5%)., l, Honey is a natural sweetener., l, It is laxative, expectorant and blood purifier., l, Honey is a tonic and immediate source of energy., It is good for children and convalescing persons., l, It is used in preparation of honey biscuits and honey, bread., Bees wax, l, It is a yellowish brown and insoluble in water but, soluble in ether. It is secretion of worker bees from, their wax glands. Bees wax is used in cosmetics,, creams, ointments, paints and polishes., l, Candles are only occasionally produced because, bees wax tends to crack in cold. The candles are,, however, smokeless., Bees venom, l, Venom from sting is used in the treatment of, rheumatoid arthritis., Propolis, l, It is resin derived from plants (auxiliary buds)., Propolis has antiseptic and antibiotic properties., Pollination, l, The biggest use of honey bee is that it is the major, pollinator of many crop plants., , LAC CULTURE, l, , l, , Diseases, l, , l, , Two common diseases are (i) Nosema disease by, protozoan Nosema apis; and (ii) Acarine disease, by parasitic mite Acarpis woodi., A number of animals feed on honey bees or attack, their hives for honey. They include wax moth, (Galleria mellonella), bear, monkey, lizard, spider,, wasp, kingcrow, black ant, etc., , Economic importance, Honey, l, It is a near neutral aromatic sweet syruph having, 1725% water, 7080% sugars, 3.3% minerals and, , l, l, , l, , l, , Lac is the resinous secretion produced by lac insect, as protective covering around its body. It belongs, to genera Laccifera or Tachardia., Lac is a complex substance having large amount of, resins, together with sugar, water and other alkaline, substances. The percentage of various, constituents are – resin 68 to 90%, dye 2 to, 10%, wax 6%, albuminous matter 5 to 10%,, mineral matter 3 to 7%, water 3%., Laccifera lacca is the common Indian lac insect., Lac insects and their products have been known to, naturalists since very early times. The first scientific, reference regarding the lac and the lac insect is the, report of Kerr and Glover in 1782., Three products from the lac insects viz, the lac, dye, lac wax and lac (resin) have been items of, trade and commerce., The lac insects have more than one host plant., Common host plants are given in the table.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▼ŐŇĚřŚĽĘŐň– ·– ▀ŇőŕŐŢĚŇĚňŚ– Őě– ○ňĽŇďńř, , Host Plants, Kusum, Babul, Ber, Palas, Peepal, Gular, Mango, Shisham, Fig, , .., .., .., .., .., .., .., .., .., , Schleichera oleasa, Acacia, nilotica, Zizyphus lylopyra, Butea monospema, Ficus religiosa, F. glomerata, Mangifera indica, Dalbergia sisso, Ficus carica, , Processing of lac, l, l, , l, l, , Life history, l, , l, , l, , The lac insect (Tachardia lacca) is a minute,, resinous insect which inserts its beak into plant, tissue, sucks juices and grows. It secretes lac from, the hind end of the body and ultimately gets covered, with lac in the “cell”. Lac is actually secreted for, its protection and not for the food of the insect., Male is red in colour and secretes bright creamy lac., Female is larger than male. The female after, fertilization lays about 200500 eggs in a cell in, which it is enclosed. After 6 weeks of laying, the, eggs are hatched into first instar nymphs. The nymphs, emerge in large number and this mass emergence of, nymph is called “swarming”. These nymph suck, the sap from host plant and grow in size. Various, morphological changes occur and after a period of, 6 to 8 weeks they are metamorphosed as a result of, which about 30% active winged males and 70%, wingless females emerge. The females get fixed on, the host plant in a resinous mass. The males walk, over the encrustation of females and fertilize them., Due to short life period males do not take major, part in the secretion of lac but female secretes lac, throughout her life and its life span is larger, than males. Thus major quantity of lac is secreted, by females., , Lac cultivation, l, , l, , l, , In order to obtain lac, lac insects cultured and the, technique of lac production is known as the lac, culture., For the purpose of propagation the older branches, containing crusts are tied with new branches and, this method is called oculation., When new crusts are formed, the old twigs are, removed (approximately 20 – 30 cm long) and this, is known as harvesting., , 685, , When the crop matures fully most of the lac is, harvested and some part is left on the host plant., The twig bearing the lac along with eggs is called, a “brood lac stick” and lac is known as “brood or, stick lac”. The processing starts with scraping of, the stick lac from the twig. Brood lac is subjected, to various processing steps to obtain purest form, of lac, called “shell lac”., The quality of lac depends upon the host plant., Palas and Ber produce the best quality lac known, as kusumi lac while Dhak lac is supposed to be, the worst and cheapest one., , Economic importance of lac, l, l, l, l, l, l, , It is used as filling material in gold jwellery., It is used in making polishes, paints and varnishes., It is utilized for preparation of toys, buttons in, pottery and artificial leather., It is used as an insulating material for electric goods., It is used as sealing wax., It is used in the manufacture of photographic, material and lithographic ink., , Lac industry in India, l, , l, , India has monopoly on the production of lac. Other, countries like Africa, Australia, Brazil, China,, Thailand, Japan etc. also produce lac., About 50% of the total lac produced in India is, obtained from chhotanagpur region. ‘India Lac, Research Institute’ Namkum, Ranchi had been, established in 1925 which is producing good quality, of white lac., , SNAKE VENOM AND ANTIVENIN, l, , l, , l, , There are two biting teeth in poisonous snakes called, fangs (modified maxillary teeth). The fangs are, connected to poison gland which are modified, salivary glands (parotid and labial)., The snake poison is of two types – neurotoxic, which causes respiratory arrest due to, neuromuscular paralysis, eg. – cobra, krait, sea, snake and hematoxic which causes wide spread, haemorrhage and destruction of body tissues,, e.g. – viper., Antivenin is prepared by immunising horses against, common poisonous snakes. For this purpose the, horse is given frequent and increasing doses of
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 686, , l, l, , ŕďőĽę– ĐĽŐńŐĹť, , toxin (venom) injection that the animal can tolerate, the toxicity. The blood from such immunized horses, is taken out and allowed to clot. Serum is separated, from clotted blood which is now called as, ‘antivenin’. Antivenin is packed in phials for, commercial purpose., Antivenin is prepared at Haffkine institute,, Mumbai., The snake venom is used in the treatment of a, number of diseases like arthritis, epilepsy, neuritis,, migraine, asthma, insomnia etc. Russell viper’s, venom is used in treatment of haemophilia as it has, coagulating property., , IMPROVEMENT OF ANIMALS, l, , The improvements of animals is brought about by, selection for desirable tracts by –, –, Inbreeding and selection., –, Outbreeding or hybridization and selection., –, Artificial insemination., , Inbreeding & Selection, l, , The process of mating among closely related, individuals is known as inbreeding. Inbreeding, combined with selection over a period of time has, resulted in many valuable breeds of domestics, animals. For example –, –, Merino sheep known for producing fine wool, are developed in Spain as a result of inbreeding, and selection conducted for about 170 years., Rambouillet sheep were developed in France, from Merino breed., –, Modern race of horses are the descendents of, three Arabian stallions imported into England, between 1686 and 1730 and mated with, several local mares of the slow and heavy, horse type., , Hybridization, l, , It is practised for creating new breeds. Some, examples of hybridization or controlled breeding, are –, , –, , –, , A cross breeding between white short horn, and the black Angus cattle produces a Blue, roan hybrid which had the vigour, rapid, growth, economical utilization of food and, high quality of beef., A cross between Brahman Bull, a race found, in India with domestic cattle of European, origin produced hybrids which showed greater, adaptability to warm and humid climate., , Artificial insemination, In India, artificial insemination was first exercised in, 1944 at Indian Veterinary Institute, Izatnagar. In this, method the semen from the better quality bulls is, collected, stored and artificially introduced into the, oviducts of females. The semen can be preserved for, long time and can also be transported to different places., Advantages of artificial insemination, –, It is very economical and makes possible a, wider use of superior bulls. A bull normally, produces 50 to 60 calves per year by natural, mating. By restoring to artificial insemination, it is possible to produce about 1000 calves in, a year from one bull., –, The semen can be collected from the bull and, used at distant places, while transportation of, bull is not practicable., –, The spread of diseases can be controlled. A, large number of foreign breeds of cows, bulls,, buffaloes and other animals have been, introduced in India. Some of these are : Jersey, (England), Ayrshire (Scotland), Brown Swiss, (Switzerland), Holstein, Freisian (Holland) etc., By cross breeding with Indian varieties, following hybrid varieties have been, developed : JerseySindhi, AyrshireSahiwal,, Brown SwissSahiwal etc. Animals like, chicken, ducks, pigs, boars, etc. have also been, improved by introduction. Boars of foreign, breed like Large White Yorkshire, Middle, White Yorkshire and Berkshire have been, introduced in India for improving Indian pigs., , l
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ▲ĚĺďŢĽŐśŕ–, , 687, , Chapter 75, , Animal Behaviour, l, l, , l, , l, , Behaviour can be defined as the way an organism, responds to stimuli in its environment., The ethology (Gr. ethos, habit; logos, study) deals, with the study of animal behaviour and is one of, the recent branches of zoology., Ethology is concerned primarily with natural, behaviour exhibited by a wide variety of animals, living under natural and seminatural conditions., Kandel (1976) defines animal behaviour as all, observable muscular and secretory responses to, changes in an animal’s internal and external, environment., Branches of ethology, – Relationships between, behaviour of a species, and its environment., Ethophysiology, – Physiological basis of, behaviour., Neuroethology, – Sensory process and, central nervous system, that, underline, a, particular behaviour., Ethoendocrinology – Relations, between, hormones and behaviour., Ethogenetics, – Genetic basis, of, behaviour., Behavioural, – Prenatal development of, embryology, behaviour pattern., Human ethology – Study, of, human, behaviour, , l, , l, , l, , Ecothology, , l, , l, , The scientific study of animal behaviour has its, origins in the work of Gilbert White (17201793), and Charles Leroy (17231789)., The most significant starting point in the, understanding animal behaviour came from the, works of Charles Darwin (18091882). He is, , l, , regarded as the father of the scientific study of, animal behaviour., Two important works of Darwin with reference to, animal behaviour are: ‘The Expression of the, Emotions in Man and the Animals’ (1873) and, ‘The Descent of Man in Relation to Sex’ (1871)., The work of Charles Whitman (18421910),, Wallace Craig (18761954) and Oskar Heinroth, (18711945) provided further basis for future, development of ethology., Konrad Zacharius Lorenz (19031989) from, Vienna, Karl Von Frisch (18861983) from, Germany and Nikolaus Tinbergen (19071988), from Holland are generally regarded as the founders, of modern ethology. In 1973, all the three were, awarded the Nobel Prize in Physiology and, Medicine for their pathbreaking contributions to, behavioural science., Karl Von Frisch’s greatest material contribution, was his work on honey bee communication (1943), and sensory biology., , INNATE AND LEARNED BEHAVIOUR, l, , Animal behaviour may be broadly classified into, two types – innate and learned behaviour., , Innate behaviour, l, l, , l, , l, , The term innate refers to the activities, characteristic of the species., Innate behaviours are also called inherited,, inherent, inborn, stereotyped or instinctive, behaviours., In this behaviour, the organism is to a large extent, stimulus bound where a pattern of stimuli trigger, a sequence of responses., Innate behaviour is an outcome of inherited, properties of the nervous system of the organism.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 688, , l, , l, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , The animal behaves in a stereotyped and predictable, manner., Innate behaviour is independent of the experience, of the individual; it is determined by heredity and, is a part of the animal’s original makeup., Innate behaviours are modified by natural, selection and also by genetic factors and the, experience of the individual., Innate behaviour is of three types – taxes, reflexes, and instincts., Taxes means the orientation of the body with, respect to the source of stimulation., The animal’s body takes up a particular direction, which may be combined with locomotion., Types of taxes, – Receptor incapable to, discriminate the source of, stimulation., Trophotaxis – Simultaneous comparison of, stimulation by bilaterally, symmetrical receptors., Telotaxis, – Taxis without simple balance, between two sources of, stimulation., Menotaxis – Also known as light compass, response, involve orientation, at a constant angle., Mnemotaxis – Taxes without involvement of, configuration stimuli., Phototaxis – Locomotory movement caused, by light., Thermotaxis – Response to temperature., Chemotaxis – Response to chemical stimuli., Geotaxis, – Response to gravity., Rheotaxis, – Response to current of water., Thigmotaxis – Response to contact., Galvanotaxis – Response to electric current., , l, , l, l, , l, l, , l, , Klinotaxis, , l, l, l, l, l, , Reflexes, like taxes are relatively stereotyped, behaviours controlled by inherited neural mechanisms., There are two types of reflexes namely tonic, reflexes and phasic reflexes., Tonic reflexes are slow, long lasting adjustments, like muscle tone, posture and equilibrium., Phasic reflexes are quick, short lived adjustment as, found in the flexure response., The reflex response is one of the major modes of, adaptation in animals., , l, l, , l, , l, , l, l, , l, , Instinct is the most controversial term in ethology, and is frequently understood as an innate behaviour, mechanism expressed in ordered movement, sequences., Instincts involve complex and often highly rigid, pattern of behaviour., A fixed action pattern (FAP) is a type of instinct, found to be same in all members of a species, (stereotype)., The notion of the fixed action pattern was, formulated by Konrad Lorenz., A fixed action pattern is a specific and stereotyped, sequence of activities that is triggered by a specific, stimulus called a sign stimulus or releaser., Fixed action pattern sequences are inherited; they, require no previous experience and are characteristic, of the species., FAP cannot be influenced in performance by, external stimuli., A classic example of FAP is provided by the study, of eggrolling behaviour of the greylag goose, (Anseranser)., Occasionally responses (FAPs) occur in the absence, of the appropriate stimulus called vacuum, behaviours., Insectivorous birds deprived of flying insects, for, example, may fly out and go through all the motions, of catching, killing and eating an imaginary insect., Some artificial stimuli were found to elicit responses, more effectively than the natural, normal stimuli., Exaggerated form of stimulus which releases a, particular behaviour pattern more effectively than, the appropriate natural stimulus is called, supernormal releaser., The building of a web by a spider is an example of, a fixed action pattern., , Learned behaviour, l, , l, l, , In addition to innate (inherited) behaviours, most, animals develop learned behaviour (acquired, behaviour) patterns from interacting with their, environment., The modification of a behaviour as a result of, experience is called learning., During learning, new relationships develop among, neurons in the nervous system, allowing the animal, to acquire new behaviours and modify inherited, responses.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ▲ĚĺďŢĽŐśŕ–, l, , l, l, , l, l, , l, l, l, l, , l, , l, , l, , l, , l, , l, , l, , Nonassociative learning is the simplest type of, learning which does not require an animal to form, an association between two stimuli or between a, stimulus and a response., Simple nonassociative learning involves, habituation and sensitization., Habituation can be defined as a decrease in, response to a repeated stimulus that has no, positive or negative consequences., Sensitization is characterized by an increased, responsiveness to a stimulus., Associative learning is a behavioural alternation, that involves an association between two stimuli or, between a stimulus and a response., The behaviour is modified or conditioned, through, the association., This form of learning is more complex than, habituation or sensitization., Two main types of associative learning are –, classical conditioning and operant conditioning., In classical conditioning, an association is formed, between a previously neutral stimulus and a, physiological response controlled by the autonomic, nervous system., Classical conditioning is also called Pavlovian, conditioning, after the Russian physiologist Ivan, Pavlov (18491936) who first described it., Pavlov worked on the condition reflex and showed, that if the presentation of food to a dog was, repeatedly accompanied by the sound of a bell, then, the dog would come to respond to the bell as if it, was food., Pavlov regarded the salivation of the food as an, unconditional response and the subsequent, salivation to the bell alone as a conditional response., Pavlov is responsible for many of the basic concepts, and can be regarded as the founder of the, experimental study of animal learning., Pavlov received a Nobel Prize in 1904 but it was, for his work on digestive physiology rather than, for his work on conditioning., In operant conditioning, associations are formed, between a completely voluntary response and the, stimulus associated with the consequences of the, response., Animal training in which behaviour is “shaped” by, rewarding or punishing acts, is an example of, operant conditioning., , l, l, , l, l, , l, , l, , l, , l, , l, , l, , 689, , Imprinting is another kind of learned behaviour., It is the imposition of a stable behaviour pattern in, a young animal by exposure to particular stimuli, during a critical period in the animal’s development., Imprinting was observed at least as early as the first, century AD. by the Roman naturalist Pliny., Konrad Lorenz was first to study imprint, objectively and systematically and given credit for, developing the concept of imprinting in 1937., Imprinting is genetically programmed to take place, during specific, sensitive periods, lasting only a few, hours or days., Although imprinting typically occurs in the very, young, it can also occur at any point during an, animals life., Imprinting is found to influence the associations of, young with their parents, mate selection, choice of, habitat and a variety of social behaviours including, parental care., Maximum work on imprinting is carried out in, groundnesting birds, but it also has been observed, in other vertebrates ranging from hoofed mammals, to domestic dogs., Osker Heinroth (1871 1945), a German zoologist,, is often given the credit for being the first to use, the term ‘imprinting’., Imprinting is a rapid form of learning and is critical, to normal behavioural development., , ANIMAL COMMUNICATION, l, l, , l, l, l, , l, l, , Communication is the passage of information from, one animal to another through messages or signals., Many signals are simple and direct, whereas others, are extremely complex, involving complex, interaction among animals., “Communication” is usually treated equivalent to, “social behaviour”., Most examples of communication are intraspecific, social interactions., The basic general characteristic of the common, concept of communication include a signal (coded, information or message), a sender and a receiver., Both sender and receiver, but not always, belong to, the same species., Animals communicate through the use of, c he m ic a l, vis ual, a uditor y, ta c tile a n d, electrical signals that can be perceived by other, individuals.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 690, , ŕďőĽę– ĐĽŐńŐĹť, , Chemical communication, l, l, l, l, , l, l, , l, , Molecules used for chemical communication, between individual animals are called pheromones., Pheromones can communicate very specific, messages that contain a great deal of information., Pheromone message last a long time, but they, cannot be changed quickly., An important feature of pheromones is that once, they are released, they remain in the environment, for a long time., When a female gypsy moth is ready to inseminated,, she releases a pheromone called gyplure., Pheromoneproducing glands are found in black, tailed deer. They include metatarsal, tarsal, anal,, interdigital and forehead glands., Scents from the metatarsal are rubbed onto other, regions of the body such as the forehead, which in, turn, is rubbed on twigs., , l, , l, l, l, , l, l, , Tactile communication, l, , Visual communication, l, , l, l, l, , l, l, , l, l, l, l, l, , Many species use visual communication which is, transmitted instantaneously and can carry a large, amount of information., Visual signals are known as displays, often include, specific movements and postures., A display or signal is a behaviour that has evolved, to influence the behaviour of other individuals., Visual signals are easy to produce, can be, changed rapidly and clearly indicate the position, of the signaler., Most animals are sensitive to light and can therefore, receive visual signals., Birds are highly visual and have evolved a vast, diversity of patterns of coloured feathers used in, communication., Because visual communication requires light, it is, not useful for many species at night., Visual communication cannot be used over great, distance., It is blocked easily by obstacles so that the sender, and receiver must be in direct line of sight., Fireflies use an enzymatic mechanism to create, flashes of light., By emitting flashes in speciesspecific patterns, fireflies, can advertise for mates at night by sending visual signals., , Auditory communication, l, , Humans are very familiar with communicating by, sound., , Compared to visual communication, auditory, communication has several advantages and, disadvantages., Sound can go around obstacles that would interfere, with visual signals., Sound is better than visual signal at getting the, attention of a receiver., Sound is good for communicating over long, distance. The humpback whales use their complex, song to locate each other over vast areas of ocean., Most invertebrates do not produce loud sound,, cicadas and crickets are marvelous exceptions., Sound may be transmitted by the air or water or via, the substrate. Many spiders, for example,, communicate by vibrations of the web., , l, l, l, , l, , Tactile communication is generally found in, situations of close bodily contact between, individuals., This communication occurs in combination with, olfactory, visual or auditory signals., Communication by touch is extremely common in, social insects such as ants, termites or honeybees., One of the most remarkable and best studied uses, of tactile communication is the dance of honeybee, to convey information about distance and direction, of the food source., Dancing bees also make sounds and carry odours, on their bodies., , Electric communication, l, , l, l, l, , In addition to being used for sensing objects in the, immediate surrounding, electric signals are used, to communicate messages in fishes., Some fish use electrosensors to gather information, about their murkey environment., Glass knife fish (Eigenmannia) males emit lower, frequencies than females., The most dominant male has the lowest frequency and, the most dominant female has the highest frequency., , HUMAN BEHAVIOUR, l, , l, , Like all other animal behaviour, human behaviour, consists of genetically determined and learned, components., An important characteristic of human behaviour, is the extent to which it can be modified by the, experience.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ○ňĽŇďń– ▲ĚĺďŢĽŐśŕ–, l, , l, l, , l, , l, l, , l, l, l, l, , The transmission of learned behaviour from, generation to generationcultureis the hallmark of, humans., The structure and many functions of our brain are, coded in our genome., Biological drives such as hunger, thirst, sexual, desire and sleepiness are inherent to our nervous, system, The emotions such as anger, aggression, fear, love,, hate and jealousy may not be solely the, consequences of learning., Human sensory systems enable him to use certain, subsets of information from the environment., The structure of human nervous system makes it, more or less possible to process certain types of, information., Humans possess the most highly advanced, communication ability of any living species., The capacity of human language is familiar to all., Language is a major and every day of human life., Verbal communication is deeply rooted in the, human evolution., , l, l, l, l, , l, , l, l, , l, , 691, , Reading and writing are relatively recent products, of human culture., The chemical senses including taste and olfaction,, are perhaps the most universal among animals., Human chemical sense appears to be crude and, insensitive., The simple fourclass taste system (salt, bitter, sour, and sweet) is applicable to humans, certainly does, not apply to all animals., Sleep is the most extreme state of inactivity. It has, been studied and described most extensively in, humans., Some motor patterns are programmed into our, nervous system., Basic similarities of facial expression and body, language in human population have little or no, contact with one another., Infants born blind smile, and show other facial, expression at appropriate times, even though, they have never observed such expressions in, others.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 692, , ŕďőĽę– ĐĽŐńŐĹť–, , Chapter 76, , Bioenergy, l, , l, , l, , l, , l, , l, , l, l, , l, , l, , l, , Bioenergy is stored energy from the sun contained, in materials such as plant matter & animal wastes,, known as biomass., Biomass is actually a product of solar energy that, has been stored by the photosynthetic activity of, plants., Biomass is present in many common waste, such, as agricultural waste, forest waste, municipal waste, food processing waste, pulp and paper mill residue,, urban wood waste, energy crops, landfills methane, and animal waste., Biomass does not add carbon dioxide to the, atmosphere as it absorbs the same amount of carbon, in growing as it releases when consumed as a fuel., Its advantages is that it can be used to generate, electricity with the same equipment or power plants, that are now burning fossil fuels., Biomass is an important source of energy and, the most important fuel worldwide after coal,, oil & natural gas., Biomass is essentially a renewable energy source, because it replenish more quickly without, permanently depleting the Earth’s natural resources, and helps to conserve soil and water., About 0.2 percent of the solar energy which, reaches the earth’s surface is converted into biomass., Biomass can be used to generate producer gas, to run irrigation pumps, to replace petrol, to get, alcohol, to generate biogas or to generate, electricity., The total quantity of matter (dry mass) in the, organisms forming a trophic level or population or, inhabiting a given region is called biomass., Most of energy which mankind has been using or, which mankind still uses, is derived directly or, indirectly from sun., Bioenergy is obtained from following types of, , l, , l, l, l, , l, l, , l, , l, , l, , l, , l, , biological sources: animal energy, biofuels and, fossil fuels., Animal energy can be classified into human, muscle power (HMP) and draught animal power, (DAP)., Energy used by labourers, farmers, and household, working women is human muscle power., Energy used by animals in agriculture and transport, is called draught animal power., DAP is of significant importance in the rural and, hilly areas, where most of the work is done by, draught animals., Biofuels are the combustible bodies of plants or, combustible product derived from biomass., Biofuels are renewable. If they are used properly, and efficiently they can help overcome energy, problems of India., Major sources of biofuels are – wood, agro, industrial residues and petroleum and oil, producing plants., Wood is defined as the main strengthening and, water conducting vascular tissues in stems & roots, of plants., Good firewoods must be highly combustible;, should produce high calories on burning; when, burnt, it should not split; can be dried easily; should, be nonresinous and should not produce smoke,, and should not release offensive smell., Dicotyledonous woods (called hard woods) are, considered better than gymnospermous woods, (called softwoods) because these burn for a longer, time and provide uniform heat., Good fire woods are – Acacia senegal (Gum Arabic),, Acacia nilotica (Kikar), Albizzia (Siris), Azadirachta, indica (Neem), Quercus (Oak), Casurina (Jhau),, Adina cordifolia (Yellow teak), Hopea (Dammar, tree), Dalbergia sisso (Shisham), etc.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ▲ĽŐĚňĚŕĹť–, l, , l, l, , l, , l, l, l, , l, , l, , l, , l, , l, , l, , l, , Bad fire woods are – Pinus roxburghii (Chir pine);, Mangifera indica (Mango); Madhuca indica, (Mahua); Bauhinia racemosa (Kachnar) etc., Fuelwood constitutes the most important source, of energy in developing countries of the world., Fuelwood consumption provides almost 43% of, the total energy consumed in developing countries, and amounts to about 14% of the total world’s, energy production., Coal, oil and natural gas represent the, photosynthetic output of green plants which, occurred millions of years ago., Forms of energy obtained from wood are, carbonisation, gasification, pyrolysis etc., Carbonisation of wood is heating of wood till it, gets converted into charcoal/carbon., Gasification is the process in which the wood is, heated and air/steam is allowed to pass over, incandescent coke to produce the producer gas., Pyrolysis is the heating of wood & waste wood to, high temperature to produce charcoal, pyroligenous, acid, tar, oil etc., Producer gas is mixture of approximately 25%, carbon monoxide, 55% nitrogen, 13% hydrogen &, 7% other gases., Producer gas is cheap & used as a fuel mainly in, glass furnaces & metallurgical furnaces. It also, serves as a fuel in gas engines to operates tractors,, motor cars etc., The following three methods have been suggested, to overcome fuel wood crisis–, –, Growing of energy plantations with fuel wood, efficiency., –, Improved chullahs should be used. The present, day chullahs have a very low efficiency, resulting in loss of useful energy., –, Processes like carbonisation (conversion of, wood into carbon), gasification (conversion, into gas) and pyrolysis (thermochemical, conversion) are being used., Energy plantations are the plantations where fuel, wood trees are grown. Such plantations would, ensure the supply of firewood to nearby areas., Coppicing means thick growth of branches from, the stump after the aerial branches have been, removed., Afforestation of all available lands (not held by, the forest department) by communities of people to, , l, , l, , l, , l, l, l, , l, , l, , l, l, , 693, , obtain ecological and environmental security,, fodder, fuel wood, fibre, fruits etc., is called social, forestry., Direct combustion is the simplest, cheapest and, most common method of obtaining energy from, biomass., Global warming is an increase in the average, temperature world wide believed to be caused by, green house effect., Biogas, also called digester, typically refers to, methane produced by the fermentation of organic, matter including manure, waste water sludge,, municipal solid waste, or any other biodegradable, feedstock, under anaerobic condition., Biogas is also called swamp gas, landfill gas &, marsh gas depending on where it is produced., Biogas contains 5070% methane, 3040% CO2,, traces of hydrogen, hydrogen sulphide and nitrogen., Stages in anaerobic digestion during biogas, formation are –, –, The facultative anaerobic microorganisms, break down the polymers into soluble, monomers with the help of enzymatic, hydrolysis. Lignin cannot be broken down by, microorganism, so it remains as residue along, with inorganic salts., –, The monomers become the substrate for micro, organisms. These are then converted into, organic acids., –, In this stage, soluble organic acids (acetic acid), are formed for the substrates of the last stage., –, Finally methanogenic anaerobic bacteria, produce methane (biogas)., Scarcity of firewood, indoor health problems with, cooking on firewood or cowdung fire, and loss of, fertilizer from burning cowdung are the problems, of biogas plants in India., Biogas can be easily stored to provide more efficient, source of energy which has wider uses than the, traditional energy sources., The production of biogas results in the formation, of a stabilised residue that acts as the fertilizer., Petroleum plants or Petrocrops are plants which, can yield large amount of latex having long chained, liquid hydrocarbons, e.g., Jatropha, Euphorbia, lathyris (family Euphorbiaceae), Brickellia (family, compositae), and other members of euphorbiaceae,, compositae, asclepiadaceae and apocynaceae.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 694, , l, l, l, , ŕďőĽę– ĐĽŐńŐĹť, , The product can be used directly or broken through, cracking to yield a number of petroleum products., Utilising petroleum plants for energy cropping was, first suggested by Melvin Calvin., Latex is fluid product of laticiferous plants that, exudes from the cut surfaces as a milky juice. It, contains long chained liquid hydrocarbons. The, latex can be used directly or broken through, cracking to yield petroleum products., , l, , l, , l, , Alcohol can be used as a fuel for automobiles either, or as 1015 per cent blend with petrol or as entire, fuel, the mixture is called gasohol., Proalcohol programme of Brazil is aimed at, completely replacing petrol with alcohol for running, automobiles., The crops which can be used for the production of, alcohol are called energy crops. Some energy crops, are maize, sugarcane, sugarbeet, tapioca and molasses., , Table : Application of bioenergy, Potential users, , Sources of bioenergy, , Industrial, , Pulping liquor and wood residues are burnt in large, boilers. Wood residues are processed using, gasification to produce fuel gas., Forestry and agricultural residues are processed using, liquifaction pyrolysis to produce biooils., , Municipal, , Municipal solid waste is burnt directly or digested, in a landfill to produce landfill gas. Municipal, sewage is processed biologically in anaerobic, digesters to producer biogas., , Residential, , Chunk wood or pellets are burnt in highefficiency, enclosed fireplaces, boxstoves, furnaces and cook, stoves., , Commercial, , Wood or agricultural residues are burnt in furnaces, to produce direct heat or to heat water in boilers., The biomass can be made into a more efficient fuel, by transforming it into pellets, briquettes and logs., , Automobile fuel, , General public, , Straw and corn stover are converted to sugars that, are fermented to produce ethanol., , Heavy vehicle fuel, , Trucking industry, , Oilseed is processed using extraction to produce bio, diesel fuel., , Bioenergy applications, , Process heat and/or electricity, , Space and water heat
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ŕŐţŚĺ– Őě– ŘśŇďň– ▓ŐőśńŐň–, , 695, , Chapter 77, , Growth of Human Population, l, , l, l, , l, , l, l, l, , l, l, l, , l, , l, , Clark (1954) defined population as a group of, individuals of a species occupying a definite, geographic area at a given time., Human population all over the world belongs to, single species i.e. Homo sapiens., The scientific study of human population is called, demography. It involves three major, phenomenon – changes in population size; the, composition of population; the distribution of, population., There are five “demographic processes”, namely, fertility, mortality, marriage, migration and, social mobility. These five processes determine, size, composition and distribution., Population growth is determined by biotic potential, and environmental resistance., Biotic potential is the capacity of organisms to, produce offspring., The environmental factors which can check the, growth of population size constitute environmental, resistance. The factors include nonavailability of, food and shelter; drought, cloud burst etc. and, certain biotic factors like pathogens, parasites,, predators etc. Thus environmental resistance does, not allow population growth to soar towards infinity., Population grows when the number of births is, greater than the number of deaths., Population size may change when individuals enter, or leave the population., If more individuals enter then population will grow, and if more individuals leave the population, the, population will shrink., The rapid increase in human population size over, a relatively short period is called human, population explosion., Human population growth rate is measured as the, ‘annual average growth rate’. It is calculated as, follows:, , Average annual growth rate (in %), , l, l, , l, l, , l, , l, , l, l, , l, , æ p - p1 ö, =ç 2, ÷ ´ 100., è p1 ´ N ø, where, P1 = Population size in the previous census,, P2 = population size in the present census., N = Number of years between the two census., The time required for a population to double itself, is called the doubling time., Population growth rate depends on factors like, fertility, mortality, migration, age and sex, structure., Fertility is the ability of reproductively active, individuals to produce babies., The number of babies produced per thousand, individuals is called birth rate (natality). The birth, rates do not indicate the current fertility pattern. It, increases the population size and population density., Total fertility rate (TFR) is the average number of, children that would be born to a woman during her, life time, assuming the agespecific birth rate of a, given year., Replacement level (RL) is the number of children a, couple must produce to replace them. The actual RL, is always slightly higher than 2.0 since some children, will die before reaching reproductive age. In developed, countries, RL is attained at 2.1, where as in developing, countries, it is around 2.7 due to a higher death rate, at immature age, and shorter life expectancy., Mortality is the death rate per thousand individuals., The death rate has dropped mainly due to improved, personal hygiene, sanitation and modern medicines., A decrease in death rate results in increased, population growth rate., The difference between the number of births and, that of deaths is the rate of natural increase. If, birth and death rates are equal a zero population, growth rate will result, which is called
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 696, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť, , demographic transition., Migration refers to the movement of individuals, between different places. The movement of, individuals into a place/country is called, immigration, while the migration out of a place/, country is called emigration. Migration between, the countries influences a nation’s population., The movement of individuals into a place/country, is called immigration, while the migration out of, a place/country is called emigration., Migration emigration and immigration are three, types of population dispersal. Population dispersal, is the movement of individuals or propagules into, or out of population for preventing overcrowding,, obtaining food, avoiding predators and other, adverse conditions., The population of individuals of different ages, within a particular population is called its age, structure, while the population of male and female, individuals in a population is called its sex, structure., The proportion of reproductively active males and, females in a population influence the population, growth. Most of the developing countries like India, have larger number of young people and represent, rapidly growing populations., Age composition or age ratio is relative abundance, of prereproductive, reproductive and post, reproductive individuals in a given population., Prereproductive is before the age of child bearing., It is 1418 years in human beings; reproductive, have individuals in the age group of child bearing,, 1445 years in woman and 1859 years for men and, postreproductive have individuals after the age, of 4559 years when they are not able to bear, children., Age pyramid is graphic representation of, abundance of individuals of different age groups, with perreproductive at the base, reproductive in, the middle and postreproductive at the top., Age pyramids are of three types – triangular age, pyramids, bell shaped age pyramid and, urnshaped age pyramid., Triangular age pyramid has high proportion of, prereproductive individuals, moderate number of, reproductive individuals, and fewer post, reproductive individuals. It represents young or, rapidly growing population., In bellshaped age pyramid the number of pre, , l, , l, , l, l, l, l, , l, , l, , l, , l, , l, , l, , reproductive and reproductive individuals is almost, equal. Post reproductive individuals are comparatively, fewer. It represents stable or stationary population, where growth rate is near zero., In urnshaped age pyramid the number of, reproductive individuals is higher than the number, of prereproductive individuals. It represents, declining or diminishing population., Growth of a population can be expressed by a, mathematical expression, called growth curve in, which logarithm of total number of individuals in, a population is plotted against the time factor., Growth curves represent interaction between, biotic potential and the environmental resistance., Population growth curves are of two major types:, the Jshaped curve and the Sshaped curve., The Jshaped curve shows three stages: lag phase,, exponential phase and crash phase., The Jshaped curve is a biopotential curve when, environmental resistance is zero; it is produced, because larger populations increase more rapidly, than smaller ones., Jshaped growth curve is shown by small population, of reindeer experimentally reared in a natural, environment with plenty of food but no predators., Lag phase is period of adaptation of animals to, new environment so is characterised by slow or no, growth in population., Logarithmic or exponential phase is characterised, by rapid growth in population which continues till, enough food is available. But with the increase in, reindeer population, there is corresponding decrease, in the availability of food which finally becomes, exhausted, which leads to mass starvation and, mortality. This sudded increase in mortality is, called populatio crash or crash phase., The Sshaped curve (sigmoid curve) is generated, when a population approaches the environment’s, carrying capacity., Carrying capacity is defined as the feeding capacity, of an environmet of a ecosystem for a population, of a species under provided set of conditions. The, limit beyond which no major increase can occur is, represented by K. When population reaches the, carrying capacity of its evironment, the, population has zero growth rate., The Sshaped curve shows three phases –, –, Early phase (Lag phase): Little or no growth, takes place due to small size of population, and lack of adaptation.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 697, , ◙ŕŐţŚĺ– Őě– ŘśŇďň– ▓ŐőśńŐň, , Middle phase (Log phase or exponential, phase): There is geometrical increase in, population size owing to abundance of food, and other favourable conditions., –, Stationary phase (Zero growth or Plateau, rate): Birth and death rates are equal, the, population stabilizes around the carrying, capacity of the environment. So there is zero, growth phase., Sshaped growth is shown by yeast cells and most, of organisms. Sigmoid growth curve was described, by Verhulst (1839)., In 1798, T.R. Malthus, a British economist, put, forward a theory of human population growth., –, He stated that population grows geometrically, when unchecked, whereas the means of its, subsistence like food grow only arithmetically., –, Naturally, after some time an imbalance would, occur in the population and the environment., –, When the imbalance reaches a certain value,, some factors like hunger, epidemics, floods,, earthquakes, war etc, will bring the population, to desired level. Such a population crash is, called catastrophic control of population., These factors were called positive checks by, Malthus., Causes of icrease in human population are –, –, Control of disease (decline in deathrate) :, In old days, people used to die in thousands, because of illness. But the development of, medical sciences has protected them from such, unnatural deaths. So there is decrease in death, rate and not the increase in birth rate that has, led to the increase in population., –, Development of agriculture : Man needs food, for all his body requirements. For this he developed, the techniques to grow more food. Thus he could, afford food for more people on this earth. Not, only agriculture, but other animals that are used, as food by man were also reproduced successfully, using scientific methods., –, Storage conditions : Food is not available at, all the times. So people used to die of, starvation when food was not available. With, the better storage conditions, the food could, be made available at all times., –, Transport : With the development of means, to go from one place to another safely, the, population also increased. Food growth in one, region could be transported to another region, –, , l, , l, , l, , l, , l, , where it could not be grown. Thus people, living in remote places were also fed., –, Protection from nature : Man formed houses, so that he can protect himself from wild, animals and enviornmental calamities. He then, formed villages, cities and countries., Consequences of over population leads to a, number of not only national but also individual, family problems. Some of them are described, below–, –, Poverty : If in a family there are more persons, and the income is less, so naturally it becomes, poor. With the addition of evey child, the, poverty increases., –, Food supply : If the population increases and, the production of food does not increase, this, will lead to a shortage of food supply., –, Hygenic condition : More people in a small, area generally make the hygenic conditions, bad. There will be an accumulation of waste, material as it is not removed that early., –, Unemployment : More number of people, means more jobs and if sufficient number of, jobs are not available, it leads to, unemployment., –, Housing problem : For more people, more, houses are required and the houses are not, built at high rate., –, Pollution : There will be an added problem of, population. As every thing is taken from, environment in excess, so it will result in, pollution., –, Education problem : It becomes difficult for, the government to provide education to all., Measures to control over population are –, (i) Education : People, particularly those in the, reproductive age group, should be educated about, the advantages of a small family. Mass media and, educational institutions can play an important role, in this campaign. (ii) Age of marriage : Raising, the age of marriage is more effective means to, control the population. (iii) Family planning :, There are many birth control measures which can, check birth rate., , BIRTH CONTROL, l, , The regulation of conception by preventive methods, or devices to limit the number of offspring is called, birth control.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, 698, , l, , l, , l, , l, , l, , l, , l, , l, , l, , ŕďőĽę– ĐĽŐńŐĹť–, , A variety of methods are known for birth control., The birth control methods which deliberately, prevent fertilization are referred to as, contraception., Contraceptive methods are preventive methods, to help woman avoid unwanted pregnancies. These, methods are of 2 main types: temporary and, permanent., Temporary methods includes natural methods (safe, period, coitus interruptus, abstinence), chemical, method, mechanical means and physiological, (oral) devices (hormonal)., A week before and a week after menses is considered, the safe period (rhythm method) for sexual, intercourse. The idea is based on the following facts:, (i) ovulation occurs on the 14th day (may be 13th, to 16th day) of menstruation; (ii) ovum survives for, about 2 days; (iii) sperms remain alive for about 3, days. This method may reduce the chances of, pregnancy by about 80 percent. It has certain, drawbacks also., Coitus Interruptus is the oldest method of birth, control. It involves withdrawal of the penis by the, male before ejaculation so that semen is not deposited, in the vagina and there is no fertilization. This method, also has some drawbacks. Male produces some, lubricating fluid from his Cowper’s glands before, ejaculation. This fluid contains many sperms., Abstinence is the best and 100% reliable way to, avoid conception is to abstain from sexual, intercourse. It is an unnatural mode of birth control,, and seems impracticable. Some couples practice, abstinence at certain times with success., Chemical means (Spermicides) : Foam tablets,, jellis, pastes and creams, if introduced into the, vagina before sexual intercourse, adhere to the, mucous membrance and immobilise and kill the, sperms by inhibiting oxygen uptake. These contain, spermicides such as lactic acid, citric acid, boric, acid, potassium permanganate and zinc sulphate., Mechanical means are of 3 types – condom;, diaphragm and cervical cap; and intrauterine, devices., Condom (Nirodh) is a rubber sheath to cover the, erect penis. It is the most widely used contraceptive, by males in India as it is cheap and easily available., It is also given free by government. It is a simple, but effective method and has no side effect. It checks, pregnancy by preventing deposition of semen in, , l, , l, , l, , l, , l, , the vagina. Condom should be used regularly and, put on before starting coital activity, otherwise, spermcontaining lubricating fluid may be left in, the vagina. Condom should be discarded after a, single use. Condom is also a safeguard against AIDS, and sexual diseases., Diaphragm and cervical cap are rubber plastic, covers that are fitted on the cervix in the female’s, vagina, and check the entry of sperms into the, uterus. These must be kept fitted for at least six, hours after sexual intercourse. They are smeared, with a spermicidal jelly or cream cap and is the, counterpart of condoms in the female., Intrauterine devices (IUDs) are plastic or metal, objects placed in the uterus by a doctor. These, include loop, copperT , spiral, ring, bow, shield,, etc. They prevent the fertilization of the egg or, implantation of the embryo. Their presence perhaps, acts as a minor irritant and this makes the egg to, move down the fallopian tubes and uterus rather, quickly before fertilization or implantation., Hormone releasing devices increases the viscosity, of the cervical mucus and thereby prevent sperm, from entering the cervix. They also maintain high, levels of progesterone in the endometrium and thus,, releasing low levels of estrogen, thereby sustaining, an endometrium unfavourable to implantation., Commonly used IUDS are plastic loop and, copper T., –, Copper T releases Cu 2+ which prevents, implantation of fertilized eggs. Copper seems, to enhance the cellular response in the, endometrium. It also affects the enzymes in the, uterus. By altering the biochemical composition, of cervical mucus, copper ions may affect sperm, motility, capaciation and survival., –, Plastic loop (especially Lippes loop) is double, Sshaped device made of polyethylene that is, nontoxic, non tissue reactive material. The, larger sized loop usually has a greater anti, fertility effect and a lower expulsion rate but, a high removal rate because of side effects, such as pain and bleedings., Drawbacks of IUDs include their spontaneous, exp u ls ion, even w ith ou t the w oma n ’s, knowledge, occasional haemorrhage; and chance, of infection., Physiological (Oral) Devices (Hormonal) includes, birth control pills.
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R. K. MALIK’S Downloaded from rkmaliksnewtonclassesranchi.wordpress.com, NEWTON CLASSES, ◙ŕŐţŚĺ– Őě– ŘśŇďň– ▓ŐőśńŐň–, l, , l, , l, , Birth control pills (oral contraceptives) check, ovulation by inhibiting the secretion of follicle, stimulating hormone (FSH) and luteinizing, hormone (LH) that are necessary for ovulation., High (but not too high) levels of these hormones, prevent follicle development (high estrogen/, progesterone from the pill inhibits GnRH release, from the anterior pituitary) and hence inhibits FSH, (estrogen effect) and LH (progesterone effect), release so follicle does not rupture. The low LH, prevents the follicle from rupturing so there is no, ovulation. Hence, no eggs are released in a woman, on the pill and conception cannot occur., The birth control pills have side effects such as, nausea, breast tenderness, weight gain and break, through bleeding (slight blood loss between, menstrual periods) and high blood pressure. On the, other hand, the oral contraceptives reduce the chances, of certain types of cancer to occur in their users., A combined pill is the most commonly used birth, control pill. It contains synthetic progesterone and, estrogen in doses high enough to check ovulation., Pill Mala D is taken daily, and the pill Saheli is, taken weekly., , I. Combined oral pill, (containing both estrogen, and progestin), , l, l, , l, , l, , l, , l, , prevent the release of, ovum from the ovary, achieved by, , l, , Blocking the pituitary se, cretion of gonadotropin, (necessary for ovulation, to occur), II. Progesterone only renders, preparations, , Also inhibit tubal mot, ility and delay the tran, sport of the sperm and, of the ovum to the, uterine cavity, , Cervical mucus thick, and scanty, thereby inhibit, , Sperm penetration, , Flow chart : Mechanism of action of oral pills, l, , Abortion is the medical termination of pregnancy, (MTP) before the foetus becomes viable. It is one, of the most widely used methods of fertility control, in the world. Certain pills act as abortants. They, function by inducing menstruation which checks, the implantation of the zygote or detaches the, implanted egg., , l, , 699, , Permanent method includes sterilization., Sterilization provides a permanent and sure birth, control. It is called vasectomy in man and, tubectomy in woman., Vasectomy involves a cut in the scrotal sac, cutting, or burning of the vas deferens (tubes that carry, sperm), and blocking both cut ends. Vasectomy, prevents the passage of sperm into seminal fluid, by blocking the vas deferens., Following vasectomy, sperm production and, hormone output are not affected. Production of, testosterone continues and its distribution does not, need the ducts. The sperm produced are destroyed, intraluminally by phagocytosis. This is a normal, process in the male genital tract, but the rate of, destruction is greatly increased after vasectomy., Vasectomy is a simpler, faster and less expensive, operation than tubectomy., Female sterilization prevents fertilization by, interrupting the passage through fallopian tube., Eggs continue to be produced because the ovaries, are intact, but they fail to pass into the uterus and, sperms fail to reach the eggs for fertilization., Female sterilization can be done as an interval, procedure, postpartum or at the time of abortion., Two procedures have become most common,, namely laparoscopy and minilaparotomy., Laparoscopy is a technique of female sterilization, through abdominal approach with a specialized, instrument called “laparoscope”. The abdomen is, inflated with gas (carbon dioxide, nitrous oxide or, air) and the instrument is introduced into the, abdominal cavity to visualise the tubes. Once the, tubes are accessible, the Falope rings (or clips) are, applied to occlude the tubes. Laparoscopy is not, advisable for postpartum patients for 6 weeks, following delivery. Haemoglobin per cent should, not be less than 8. There should be no associated, medical disorders such as heart disease, respiratory, disease, diabetes and hypertension., Minilaparotomy (minilap operation) is a, modification of abdominal tubectomy. It is a much, simpler procedure requiring a smaller abdominal, incision of only 2.5 to 3 cm conducted under local, anaesthesia. The minilap/Pomeroy technique is, considered a revolutionary procedure for female, sterilization. It has the advantage over other methods, with regard to safety, efficiency and ease in dealing, with complications. Minilap operation is suitable, for postpartum tubal sterilization.
