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CHAPTER-WISE FOCUS AREA TOPICS, BIOLOGICAL CLASSIFICATION, Table 2.1 Characteristics of the Five, Kingdoms (RH. Whittaker's Classification), 2.3 Kingdom Fungi, (General characters of Fungi, page 22 and, 23), 2.6 Viruses (page 25 and 26), PLANT KINGDOM, 3.1 Algae (General characters of, algae, page 30 to 32) and Table 3.1, Divisions of Algae and their main, characteristics(page 33), 3.2 Bryophytes (page 34 to 35), MORPHOLOGY OF ANGIOSPERMS, 5.1 The Root, 5.1.2 Modifications of Root 5.2 The Stem, 5.2.1 Modifications of Stem, 5.3 The Leaf 5.4 The Inflorescence, 5.5 The Flower, 5.5.1 Parts of a Flower( 5.5.1.1 to 5.5.1.4), 5.9.1 Fabaceae (Floral characters and, Floral Formula), 5.9.3 Liliaceae (Floral characters and Floral, Formula), ANATOMY OF FLOWERING PLANTS, 6.1.1 Meristematic tissues, 6.1.2.2 Complex Tissues, 6.2.1 Epidermal Tissue System, 6.2.3 The Vascular Tissue System, 6.3.1 Dicotyledonous root, 6.3.2 Monocotyledonous root, 6.3.3 Dicotyledonous stem, 6.3.4 Monocotyledonous stem, 6.3.5 Dorsiventral (Dicotyledonous leaf), CEL THE UNIT OF LIFE, 8.4 Prokaryotic cells, 8.5.1 Cell Membrane, 8.5.4 Mitochondria, 8.5.5 Plastids, 8.5.6 Ribosomes, 8.5.10 Nucleus, , Prepared by, , CELL CYCLE AND CELL DIVISION, 10.1.1 Phases of Cell Cycle, 10.2 to 10.2.5 M Phase, Prophase,, Metaphase.Anaphase. Telophase. Cytokinesis:, 10.4 to 10.4.2- Meiosis,Meiosis I and Meiosis II, TRANSPORT IN PLANTS, 11.2.1 Water Potential, 11.2.2 Osmosis 11.2.3 Plasmolysis, 11.2.4 Imbibition, 11.3.1 How do plants absorb water?, 11.3.2.2 Transpiration Pull, 11.4 Transpiration, MINERAL NUTRITION, 12.2.1 Criteria for essentiality of elements, 12.6.1 Nitrogen cycle, 12.6.2 Biological Nitrogen fixation, Symbiotic, biological nitrogen fixation, Nodule Formation., PHOTOSYNTHESIS IN HIGHER PLANTS, 13.3 Where does Photosynthesis take place?, 13.4 How many types Pigments are involved in, Photosynthesis?, 13.5 What is light reaction?, 13.6 The Electron Transport, 13.6.1 Splitting of water, 13.6.2 Cyclic and Non-cyclic Photophosphorylation, 13.6.3 Chemiosmotic Hypothesis 13.7.1 The, Primary acceptor of CO2, 13.7.2 Calvin cycle, RESPIRATION IN PLANTS, 14.2 Glycolysis 14.3 Fermentation, 14.4 Aerobic respiration, 14.4.1 Tricarboxylic Acid Cycle, 14.4.2 ETS and Oxidative Phosphorylation, PLANT GROWTH, 15.4.1 Plant Growth Regulators Characteristics, 15.4.3.1 Auxins, 15.4.3.2 Gibberellins, 15.4.3.3 Cytokinins, 15.4.3.4 Ethylene, 15.4.3.5 Abscisic acid, 15.5 Photoperiodism, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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BIOLOGICAL CLASSIFICATION, , FIVE KINGDOM CLASSIFICATION, ,  R.H. Whittaker proposed the five-kingdom classification in 1969.,  This classification was based upon certain characters like mode of nutrition, thallus, organization, cell structure, phylogenetic relationships (evolutionary relationship) and, reproduction.,  This five kingdoms include Monera, Protista, Fungi, Plantae and Animalia., , III.KINGDOM FUNGI,  Fungi are eukaryotic heterotrophic organisms.,  They show a great diversity in morphology and, habitat.,  Common types include,,  Yeast (used to make bread and beer),  Puccinia (causative organism of wheat-rust, disease),  Penicillium (Source of antibiotic called, penicillin),  They are filamentous, with the exception of, unicellular Yeasts.,  The body of fungi consists of long, slender, thread-like structures called hyphae.,  The network of hyphae is known as mycelium., , Prepared by, ,  Some hyphae are continuous tubes filled, with multinucleated cytoplasm. These are, called coenocytic/aseptate hyphae.,  Others have septae or cross walls in their, hyphae they are called septate hyphae.,  Fungal cell wall is made up of chitin &, polysaccharides.,  Most fungi are heterotrophic and absorb, soluble organic matter from dead substrates, and hence are called saprophytes.,  The fungi that depend on living plants and, animals for their food are called parasites.,  Fungi can also live as symbionts in, association with algae as lichens and with, roots of higher plants as mycorrhiza., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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, , , , , , , REPRODUCTION IN FUNGI, Fungi reproduce vegetatively by, fragmentation, budding or fission., Asexual reproduction takes place through, spores called conidia, sporangiospores,, aplanospores or zoospores., Fungi reproduce sexually through oospores,, ascospores, zygospore or basidiospores., Sexual cycles involves the following steps, Plasmogamy: fusion of protoplasms, between two motile or non-motile gametes., Karyogamy: fusion of two nuclei, ,  VIRUS,VIROIDS,PRIONS AND LICHENS,  Five kingdom system of classification do not, include Virus, Viroids,Prions and Lichens.,  Viruses are non-cellular organisms having, inert crystalline structure outside the living, cell.,  Once they enter the living cell, they take over, the machinery of living cell to replicate, themselves.,  The name virus (means venom or poisonous, fluid) was given by Pasteur.,  D.J. Ivanowsky (1892) recognized certain, microbes that cause mosaic disease of, tobacco.,  They were smaller than bacteria because they, passed through bacteria-proof filters.,  M.W. Beijerinek (1898) demonstrated that, the extract of the infected plants of tobacco, could cause infection in healthy plants and, called the fluid as Contagium vivum, fluidum (infectious living fluid)., , Prepared by, ,  Meiosis: zygote undergoes meiosis resulting, in haploid spores.,  In higher fungi, karyogamy is delayed and, occurs just before meiosis.,  In such cases opposite nuclei remain paired, (n+n,Dikaryon) before fusion. Such cells are, called dikaryotic cells.,  Based on the morphology of the mycelium,, mode of spore formation and fruiting bodies,, the kingdom fungi are classified into 4 classes, ,  W.M. Stanley (1935) showed that viruses, could be crystallized and crystals consist, largely of proteins.,  In addition to proteins, viruses also contain, genetic material (RNA or DNA). No virus, contains both RNA & DNA.,  A virus is a nucleoprotein and the genetic, material is infectious.,  Usually plant viruses have single stranded, RNA; bacteriophages have double stranded, DNA and animal viruses have single or, double stranded RNA or double stranded, DNA,  The protein coat, called capsid is made of, small subunits called capsomeres, protects, the nucleic acid.,  These capsomeres are arranged in helical or, polyhedral geometric forms., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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PLANT KINGDOM, , , , , , , , , , , , ALGAE, Algae are chlorophyll-bearing, simple,, ii. Asexual Reproduction, thalloid, autotrophic and largely aquatic,  It occurs by a number of accessory spores,, (both freshwater and marine) organisms., such as zoospores, aplanospores,, The important salient features of algae are, akinetes,etc., given below,  The most common being the zoospores,, The plant body (thallus) is without, which are flagellated and hence motile., differentiation., iii.Sexual reproduction:, The basic form and size of algae is highly,  Through fusion of two gametes., variable,They include,  It is of many types:, o Microscopic unicellular forms: E.g.,  Isogamous: Fusion of gametes similar in, Chlamydomonas., size. They may be flagellated (e.g., o Colonial forms: E.g. Volvox, Chlamydomonas) or nonflagellated (nono Filamentous forms: E.g. Ulothrix and, motile, e.g. Spirogyra)., Spirogyra.,  Anisogamous: Fusion of two gametes, o A few marine forms such as kelps, form, dissimilar in size. E.g. Some species of, massive plant bodies. Reproduction, Chlamydomonas., The algae reproduces vegetatively, asexually,  Oogamous: Fusion between one large, nonand sexually., motile (static) female gamete and a smaller,, i. Vegetative Reproduction, motile male gamete. E.g. Volvox, Fucus., It occurs by fragmentation. Each fragment, gets develop into a new thallus/organism., ECONOMIC IMPORTANCE OF ALGAE, At least half of the total carbon dioxide,  used to culture bacteria.,  Algin obtained from brown algae and, fixation on earth is carried out by them. , carrageen from red algae used commercially., Increase oxygen level in the environment.,  Chlorella and Spirullina are unicellular, Many species like Laminaria, Sargassum, algae, rich in protein and used as food, etc. are used as food., supplement even by space travelers., Agar obtained from Gelidium and Gracilaria, are used in ice-creams and jellies and also, CLASSIFICATION OF ALGAE, , BRYOPHYTES,  They are also called amphibians of the, plant kingdom because they can live in soil, but need water for sexual reproduction., Prepared by, ,  They occur in damp, humid and shaded, localities., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 Their body is more differentiated than that, of algae.,  It is thallus-like and prostrate or erect, and, attached to the substratum by unicellular, or multicellular rhizoids.,  They lack true roots, stem or leaves. They, may possess root-like, leaf-like or stem-like, structures.,  The main plant body is haploid. It produces, gametes, hence is called a gametophyte.,  The male sex organ (antheridium) produces, biflagellate antherozoids.,  The female sex organ (archegonium) is, flask-shaped and produces a single egg., ,  Antherozoids are released into water where, they come in contact with archegonium.,  An antherozoid fuses with an egg to form a, zygote.,  Zygotes do not undergo meiosis, immediately. It divides and produce a, multicellular body called a sporophyte.,  Sporophyte is not free-living but attached to, the photosynthetic gametophyte and derives, nourishment from it.,  Some cells of the sporophyte undergo, meiosis to produce haploid spores.,  These spores germinate to form new, gametophyte., , ECONOMIC IMPORTANCE,  Bryophytes in general are of little economic, , importance.,  (i) Some mosses provide food for herbaceous, mammals, birds and other animals., ,  (ii) Species of Sphagnum (a moss), provides, peat that have long been used as fuel.,  (iii)Sphagnum has the capacity to hold, , water and hence it is used as packing, material for transshipment of living, material.,  Bryophytes are divided into liverworts and Mosses., , Prepared by, , (iv)They have great ecological importance, because of their important role in plant, succession on bare rocks/soil., Mosses along with lichens decompose rocks, making the substrate suitable for the, growth of higher plants., (v) Mosses from dense mats on the soil, they, reduce the impact of falling rain and prevent, soil erosion., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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MORPHOLOGY OF FLOWERING PLANTS, , , , , , , , , , , , , , , , , , , , , , , , THE ROOT, Primary roots are the direct elongation of, the radicle., Primary roots bear lateral roots of several, orders that are referred to as secondary,, tertiary roots, etc., Primary roots along with lateral roots forms, the Tap root system. Example: Mustard,, Gram, etc., , , , , , Functions of root system, 1.Absorption of water and minerals from the soil., 2. Storage of food materials., , MODIFICATION OF ROOTS, Roots are modified for storage, nitrogen, fixation, aeration and support., , Tap root of carrot, turnip and adventitious, root of sweet potato get swollen to store food., , Prop root of Banyan and Stilt root of maize, and sugarcane are, supporting roots coming, out, THE STEM, Stem is the aerial part of the plant and, , develops from plumule of the embryo., Stem bears nodes and internodes., , The region of stem where leaves are born are, called nodes and portion between two nodes, are called internodes., , The stem has axillary buds or terminal buds., The main function of stem is spreading, branches bearing leaves, flowers and fruits., MODIFICATION OF STEMS, Underground stem of potato, ginger and, , turmeric are modified to store food., They also act as organ of perennation in, unfavorable conditions., Stem tendril help plants to climb as in, cucumber, pumpkins, and grapes., , Axillary buds of stem may modify into woody,, straight and pointed thorns as in Citrus and, Bougainvillea., , Plants of arid regions modify their stem to, flattened (Opuntia), fleshy cylindrical, (Euphorbia) stem called phylloclade., , They help in photosynthesis and storage of, water., , Prepared by, , In monocot plants, primary root is short, lived after seed germination., It is replaced by large number of roots at the, base of the stem. Such roots constitute the, Fibrous root system. Eg. Wheat, rice etc., The roots that arise from any parts of the, plant other than radicle are called, adventitious roots. Example- Grass,, Banyan tree, Maize, etc., 3.Providing a proper anchorage to the plant, parts., 4.Synthesis of plant growth regulators, from lower node of stems., In Rhizophora, roots come out of the ground, and grow vertically upwards, These roots are, called Pneumatophores., They help to get oxygen for respiration as it, grows in swampy areas., , Stem arranges leaves in a way that it gets, direct sunlight to perform photosynthesis., It also conducts water and minerals from root, to leaves and product of photosynthesis from, leaves to other parts., Some stem perform special functions like, storage of food, support, protection and, vegetative propagation., , In some plants, a slender lateral branch arises, from the base of the main axis and after, growing aerially for some time arch, downwards to touch the ground (Stolons)., Example- mint and jasmine, A lateral branch with short internodes and, each node bearing a rosette of leaves and a, tuft of roots is found in aquatic plants, (Offset). Example- Pistia and Eichornia, In some plants lateral branches originate from, the basal and underground portion of the, main stem., These branches grow horizontally beneath the, soil and then come out obliquely upward, giving rise to leafy shoots ( Sucker). Examplebanana, pineapple, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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THE LEAF,  Leaf is a green,lateral flattened outgrowth,  In leguminous plants the leaf base may, which is borne on the node of a stem., become swollen, which is called the Pulvinus.,  Each leaf bears a bud in its axil called as the,  The structure that holds the leaf is called, axillary bud, which later develops into a, petiole., branch.,  The green exposed part of the leaf is known as,  Leaves are specialized organs for, lamina.  Lamina bears the veins or veinlets, photosynthesis., .Middle prominent vein is called midrib.,  Leaves originate from shoot apical meristem,  Veins provide rigidity to the leaf blade and act, and are arranged in an acropetal order., as channel for transport of water and,  A typical leaf consists of three parts- Leaf, minerals., base, Petiole, Lamina.,  Leaf is attached with stem by Leaf Base which, may bear two small leaf like structure called, stipule., INFLORESCENCE,  During the flowering season, the vegetative apex of the stem gets converted into a floral, meristem.,  The arrangement of flowers on the floral axis is termed as inflorescence.,  Based on whether the floral axis continues to grow or end in a flower,infloresence are of 2 main, types , racemose and cymose.,  Racemose,  Cymose,  The main axis continuous to grow., ,  Flowers are borne laterally in an acropetal, succession., ,  Example- Radish, Mustard., , , Main axis terminates in flower having limited, growth., Flowers are borne in a basipetal succession., Example- Jasmine, Bougainvillea, , THE FLOWER,  Flower is the part of angiosperm plants for, sexual means of reproduction.,  Stalk of the flower is called pedicel,  A typical flower has four whorls arranged on a, swollen end of pedicel called thalamus/, receptacle.,  They are Calyx, Corolla, Androecium and, Gynoecium.,  In flower like lily, the calyx and corolla are not, distinct and are called perianth,  When a flower has both androecium and, gynoecium, the flower is called bisexual.,  A flower having either androecium or, gynoecium only is called unisexual.,  When a flower can be divided into two equal, halves in any radial plane passing through the, centre, it is said to be actinomorphic (radial, symmetry) as in Mustard, Datura, and Chili.,  When flower can be divided into two similar, halves only in one vertical plane it is, zygomorphic as in Pea, Gulmohar, Cassia etc., , Prepared by, ,  A flower is asymmetric (irregular) if it cannot, be divided into two equal halves by any vertical, plane passing through the centre.,  Example- canna,  When Floral appendages are in multiple of, 3,4 or 5 the flowers are said to be trimerous,, tetramerous and pentamerous respectively.,  Flower with bracts are called bracteates and, without it is ebracteate.,  Based on the position of ovary with respect to, other floral part on thalamus, flowers are of, following types:, , ,  Hypogynous flower– Ovary occupies the, highest position. The ovary in such case is, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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, , , , , , , , , , , , , , called superior. Eg. Mustard, brinjal and, china rose., Perigynous flowers-If the gynoecium is, situated at the centre and other parts are on, the rim at same height. Ovary is called halfinferior., PARTS OF A FLOWER, Calyx is the outermost whorl of the, flower; its members are called sepals., They are generally green and leafy;, protect the flower in bud stage., It may be gamosepalous (sepals united), or polysepalous (sepals free)., AESTIVATION, The mode of arrangement of sepals or petals, in floral bud with respect to other members, of the same whorl is called aestivation., Valvate, sepals or petals in a whorl just touch one, another at the margin, without overlapping., E.g. Calotropis., Twisted :, One margin of the appendage overlaps that, of the next one. E.g. china rose., Imbricate :, The margin of sepals or petals overlap one, another but not in any particular direction, as in Cassia and gulmohur., ,  Epigynous flowers- The margin of thalamus, grows to completely cover the ovary. Ovary is, said to be inferior., ,  Corolla is composed of petals.,  Petals are brightly coloured to attract, the insects for pollination.,  They may be Polypetalous (petals are, free) or Gamopetalous (petals are united, or fused)., Vexillary,  In pea and bean flowers, there are five, petals- the largest (standard) overlaps the, two lateral petals (wings) which in turn, overlap two smallest anterior petals (keel).,  This type of aestivation is known as, vexillary or papilionaceous., , THE ANDROECIUM,  Androecium represent the male reproductive, parts of flower and consists of stamens.,  Each stamen consists of a stalk or filament, and an anther.,  Pollen grains are produced in pollen sacs of, the anther.,  Sterile stamen is called Staminode.,  When stamens are attached with petals,such, stamens are called epipetalous (Brinjal)., ,  A stamen is called Epiphyllous when it is, attached to the perianth. E.g. lily,  If Stamens in a flower are free,they are called, polyandrous.,  Stamens may be united in one bundle, (monoadelphous), two bundles, (diadelphous), more than two, (polyadelphous)., , THE GYNOECIUM,  Female reproductive part of flower is made, up of one or more carpels.,  Each carpel has stigma,style and ovary.,  Ovary is the enlarged basal part on which, lies the elongated tube, the style.,  The stigma usually at the tip of the style.It, receives pollen grain.,  When more than one carpel is present, it, may be free (apocarpous) as in lotus and, , Prepared by, , rose or fused together (syncarpous) as in, mustard and tomato.,  After fertilisation, ovules change into seeds, and ovary mature into fruits., PLACENTATION,  The arrangement of ovules within the ovary is, called placentation.,  Marginal: Ovules are arranged along the fused, margins of ovary., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 Axile: Margins of carpels fuse to form central,  Free central: Ovules borne on central axis,, axis.The ovules are attached to placenta in a, lacking septa., multilocular ovary .,  Basal: Placenta develops at the base of,  Parietal: Ovules develop on inner wall of ovary., ovary., , SEMI -TECHNICAL DESCRIPTION OF A TYPICAL FLOWERING PLANT,  The plant is described beginning with its, P for perianth, A for androecium and G for, habit, vegetative characters and then floral, Gynoecium., characters(inflorescence and flower parts).,  Fusion is indicated by enclosing the figure,  The floral formula is represented by some, within bracket and adhesion by a line, symbols., drawn above the symbols of the floral parts.,  In the floral formula, Br stands for bracteate,  A floral diagram gives information about, K stands for calyx , C for corolla,, number and fusion of floral parts,their, arrangement and relation., Family Fabaceae This family was earlier called Papilonoideae, a subfamily of family Leguminosae.,  Economic importance, Flower: bisexual, zygomorphic, Corolla: petals five, polypetalous, papilionaceous,, consisting of a posterior standard, two lateral wings,, two anterior ones forming a keel (enclosing stamens, and pistil), vexillary aestivation,  Androecium: ten, diadelphous, anther dithecous,  Plants belonging to this family are sources of pulses, like Gram, Arhar, Bean. Pea etc. and edible oils like, groundnut, soybean, etc., , , ,  Some plants belonging to the family are sources of dye like indigofera,fibre like sunhemp,fodder, like Sesbania, Trifolium.,  Ornamentals plants like Lupin and Sweet pea are also belongs to fabaceae ., Family Liliaceae,  Commonly called the ‘Lily family’ and is a,  It includes ornamental plants (Tulip), Medicine, characteristic representative of, (Aloe) ,vegetable (Asparagus) and colchicine, monocotyledonous plants., (Colchicum autumnale).,  Floral characters,  Inflorescence: solitary / cymose; often, umbellate clusters,  Flower: bisexual; actinomorphic,  Perianth tepal six (3+3), often united into tube;, valvate aestivation,  Androcium: stamen six, (3+3),  Gynoecium: tricarpellary, syncarpous, ovary, superior, trilocular with many ovules; axile, placentation, , , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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ANATOMY OF FLOWERING PLANTS, Tissue, A tissue is group of cells having common origin and performing a common function., There are two types of Tissues in plants, a) Permanent tissue and b) meristematic tissue, MERISTAMATIC TISSUES, Growth in plants is largely restricted to specialised regions of active cell division called, meristems.,  Based on its position in the plant body, the meristem is divided into three types – apical, meristem, intercalary meristem and lateral meristem., •, Apical meristem, •, Intercalary meristem, •, Lateral meristem, , , , , , , • Present along the sides of, at nodal region, the plant body, • Primary meristem, • Secondary meristem, • Help the grasses to regenerate • Appears later stage of, parts removed by grazing, growth and responsible for, herbivores., increase in thickness ., Both apical meristems and intercalary meristems are primary meristems because they appear, early in life of a plant and contribute to the formation of the primary plant body., Axillary bud : The buds which are present in the axils of leaves and are responsible for forming, branches or flowers., COMPLEX TISSUES, Complex tissue consists of different types of cells but perform same function., Xylem and phloem constitute the complex tissues in plants and work together as a unit., XYLEM,  Tracheids are elongated or tube like cells with, Xylem functions as tissue for transport of, water and minerals from roots to the stem, thick and lignified walls and tapering ends., and leaves.,  Vessel is a long cylindrical tube-like structure, Xylem is composed of four different types of, made up of many cells called vessel members., elements, namely, tracheids, vessels, xylem,  Gymnosperms lack vessels in their xylem., fibres and xylem parenchyma.,  Vessel members are inter-connected by, perforations in their common walls.,  In flowering plants tracheids and vessels are, the main water transporting elements.,  Xylem fibers are dead cells with lignified cell, wall and central lumen.,  Xylem parenchyma are living and thin-walled, cells, and their walls are made up of cellulose.,  Radial conduction of water takes place by, specialise ray parenchyma cells., , • Occurs at the tips of, roots and shoots, • Primary meristem, • Increase the length of, plant, , , , , , , , , , • Occurs between mature tissue, , ,  Protoxylem & metaxylem,  Primary xylem is of two types – protoxylem, and metaxylem.,  The first formed primary xylem elements are, called protoxylem and the later formed, primary xylem is called metaxylem, Prepared by, ,  In stems, the protoxylem lies towards the, centre (pith) and the metaxylem lies towards, the periphery of the organ, this type of, primary xylem is called endarch.,  In roots, the protoxylem lies towards, periphery and metaxylem lies towards the, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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centre, such arrangement of primary xylem is, called exarch, PHLOEM,  Phloem transports food materials, usually, cytoplasm and a large vacuole but lacks a, from leaves to other parts of the plant., nucleus.,  Phloem in angiosperms is composed of sieve,  The functions of sieve tubes are controlled by, tube elements, companion cells, phloem, the nucleus of companion cells., parenchyma, and phloem fibres.,  The companion cells are specialised, parenchymatous cells, which are closely, associated with sieve tube elements.,  Phloem parenchyma is made up of elongated,, cylindrical cells which have dense cytoplasm, and nucleus.,  Phloem parenchyma is absent in most of the, monocotyledons.,  Phloem fibres (bast fibres) are made up of, sclerenchymatous cells.,  These are generally absent in the primary,  Instead of sieve tubes and companion cells, phloem but are found in the secondary, Gymnosperms have albuminous cells and, phloem., sieve cells.,  Phloem fibres of jute, flax and hemp are used,  Sieve tube elements are also long, tube-like, commercially., structures, arranged longitudinally and are, , The first formed primary phloem consists of, associated with the companion cells., narrow sieve tubes and is referred to as proto,  Their end walls are perforated in a sieve-like, phloem., manner to form the sieve plates., , Later formed phloem has bigger sieve tubes,  A mature sieve element possesses a peripheral, and is referred to as meta phloem., THE TISSUE SYSTEM,  On the basis of their location and function all the tissues of a plant can be classified in to three, tissue systems., EPIDERMAL TISSUE SYSTEM, transpiration and gaseous exchange.,  It forms the outermost covering of whole,  Each stoma is composed of two bean, plant body, which consists of epidermal, shaped cells known as guard cells which, cells, stomata, epidermal appendages, enclose stomatal pore., (trichomes and hairs).,  Epidermal cells adjacent to the guard cells,  Epidermis forms outermost protecting layer, become specialised in their shape and size, made up of is single layered parenchyma, and are known as subsidiary cells., cells.,  The stomatal aperture, guard cells and the,  The outside of the epidermis is often covered, surrounding subsidiary cells are together, with a waxy thick layer called the cuticle, called stomatal apparatus., which prevents the loss of water.,  The root hairs are unicellular elongation of,  Cuticle is absent in roots., epidermal cells and help in absorption of,  Stomata are structures present in the, water and mineral nutrients., epidermis of leaves.,  Trichomes are multicellular hairs present,  Stomata regulate the process of, on the stem., , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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, , , , , , , , VASCULAR TISSUE SYSTEM, The vascular system consists of complex, tissues, xylem and phloem that together, form vascular bundles., the arrangement of xylem and phloem are, different in roots and stem., In roots the xylem and phloem seen in, different radii. Such vascular bundles are, called radial vascular bundles.(Roots), In stem the xylem and phloem are arranged, ANATOMY OF DICOT ROOT, ,  The outermost layer of dicot root is, epiblema containing unicellular root hairs.,  The cortex consists of several layers of thinwalled parenchyma cells., ANATOMY OF MONOCOT ROOT, , in the same radius. Such vascular bundles, are called conjoint (stem and leaves).,  Conjoint vascular bundles may be open or, closed,  In open vascular bundle cambium ( a, meristem) is seen in between xylem and, phloem as in dicot stem,  In closed vascular bundle cambium is, absent as in monocot stem.,  The innermost layer of cortex is called, endodermis,,  Endodermal cell wall has thick deposition of, waxy material suberin,which is impermeable, to water,it is called casparian strip.,  Inner to endodermis lies a few layers of, thick-walled parenchyomatous cells referred, to as, pericycle.,  Xylem and phloem groups are limited in, number .Xylem elements are polygonal in, outline.,  The parenchymatous cells which lie between, the xylem and the phloem are called, conjuctive tissue.,  All tissues on the inner side of the, endodermis such as pericycle, vascular, bundles and pith constitute the stele., ,  The anatomy of the monocot root is similar, to the dicot root in many respects.,  It has epidermis, cortex, endodermis,, pericycle, vascular bundles and pith.,  Xylem and phloem groups are more in, number than dicot root.,  Pith is large and well developed., , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 Dicot Root, 1. Cortex is comparatively narrow, 2. Endodermis is less thickened casparian, stripes are more prominent, 3. The xylem and phloem bundles varies, from 2 to 6, 4. Pith is reduced or sometimes absent, 5 .Secondary growth takes place with the, help of cambium.,  ANATOMY OF DICOT STEM, , , , , , , , , , , , , , ,  Monocot Root, 1. Cortex is very wide., 2. Casparian strips are visible only in young, Roots, 3. Xylem and phloem are more than 6., (polyarch)., 4. Well developed and large pith is present., 5. Secondary growth is absent., , , , , , ,  Epidermis forms the outermost protective, layer of the stem.,  The multiple layers of cells arranged in, between epidermis and pericycle constitute, the cortex.,  It has three sub-zones,  Hypodermis: Layers of collenchymatous, cells just below the epidermis, which provide, mechanical strength to the young stem.,  Cortical layers: Layers of round thin walled, , , , , , , , , , parenchymatous cells with intercellular, spaces., Endodermis: The innermost layer of the, cortex rich in starch grains and hence called, Starch sheath, Pericycle is present on the inner side of the, endodermis and above the phloem., Vascular bundles limited in number and, arranged in a ring form., Vascular bundles are conjoint and open., Paren-chymatous tissue seen in between, vascular bundles constitute medullary, rays., A large number of rounded, parenchymatous cells occupy the central portion, of the stem constitute the pith., Conjoint vascular bundles may be open or, closed, In open vascular bundle cambium ( a, meristem) is seen in between xylem and, phloem as in dicot stem., , ANATOMY OF MONOCOT STEM,  The hypodermis is made up of, sclerenchyma.,  Vascular bundles are conjoint and closed.,  Vascular bundles are numerous and, scattered in the ground tissue,  Each vascular bundle is surrounded by a, sclerenchymatous bundle sheath.,  Phloem parenchyma is absent in monocot, stem and they have water-containing, cavities within the vascular bundles., , , Dicot Stem,  Monocot Stem, 1. The ground tissue is differentiated into, 1. The ground tissue is made up of similar, cortex, endodermis, pericycle and pith., cells. (Homogeneous), , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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2. The vascular bundles are arranged in a, ring, 3. Vascular bundles are open, without, bundle sheath., , , , , , , , , , 2. The vascular bundles are scattered in the, ground tissue., 3. Vascular bundles are closed,and, surrounded, by sclerenchymatous bundle sheath., 4. Secondary growth is absent., , 4. The stem shows secondary growth., ANATOMY OF DOSIVENTRAL (DICOT) LEAF, The leaf lamina of a dorsiventral leaf has 3 parts: epidermis, mesophyll and vascular system., The upper epidermis is called adaxial epidermis and lower one is called abaxial epidermis., More number of stomata are present on the abaxial epidermis., There are two types of cells in the mesophyll,upper layer called palisade parenchyma and lower, spongy parenchyma., There are numerous large spaces and air cavities between the cells of spongy parenchyma., Vascular bundles can be seen in the midrib and veins., Vascular bundles are surrounded by a layer of thick-walled bundle sheath cells., , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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CELL .THE UNIT OF LIFE, INTRODUCTION, Cell is the fundamental structural and, functional unit of all living organisms.,  Antony Von Leeuwenhoek first saw and, described a live cell.,  Robert Brown discovered nucleus., , , All organisms are composed of cells., Some organisms are composed of a single, cell and are called unicellular organisms.,  Others composed of many cells,they are, called multicellular organisms., , , , PROKARYOTIC CELLS,  Represented by bacteria, blue-green algae,, mycoplasma and PPLO.,  Smaller and multiply more rapidly than, eukaryotic cells.,  The four basic shapes of bacteria are, bacillus (rod shaped) coccus (spherical),, vibrio (comma shaped) and spirillum (spiral)., ,  All prokaryotes have a cell wall that, surrounds the plasma membrane.,  There is no well defined nucleus and hence, the genetic material is basically naked .,  A specialized differentiated form of cell, membrane called mesosome is present., , EUKARYOTIC CELLS,  Eukaryotic cells are present in Protista,, plants, Animals and Fungi.,  The cells contain well organized nucleus, with nuclear membrane.,  The genetic materials are arranged in, CELL MEMBRANE,  The cell membrane is composed of lipids, that are arranged in a bilayer.,  The lipids are arranged within the, membrane with the polar head towards the, outer sides and the hydrophobic tails, towards the inner part.,  This arrangement ensures that the nonpolar, tail of saturated hydrocarbons is protected, from the aqueous environment., , , , chromosomes.,  Plants cells differ in having cell wall,, plastids and large central vacuole as, compared to animal cells.,  Animal cells have centrioles, which are, absent in plant cell.,  The lipid component is mainly composed of, phosphoglycerides.,  Later it was found that protein is also, present in cell membrane.,  Ratio of protein and lipids varies in different, cells.,  Membrane protein may be integral or, peripheral. Integral protein remains buried, in membrane but peripheral protein lies on, the surface.,  Singer and Nicholson (1972) proposed fluid, mosaic model.,  According to this model the quasi-fluid, nature of lipid enables lateral movement of, protein within the bilayer of lipids.,  The main function of plasma membrane is, the transport of molecules across it., ,  ACTIVE TRANSPORT,  PASSIVE TRANSPORT,  1.The transport involves an expenditureof 1. The cells do not spend energy in,  energy by the cells.,  passive transport., , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 It occurs against the concentration, gradient.,  It is a rapid process., MITOCHONDRIA,  Mitochondria is double membrane bound, structure with the outer membrane and, inner membrane dividing its lumen in two, compartments.,  The inner membrane forms a number of, infoldings called cristae towards the matrix.,  Mitochondria are sites for aerobic, respiration.,  They produce cellular energy in form of ATP, so, they are called power house of the cells.,  The matrix of mitochondria also contain, , , , PLASTIDS, ,  This transport is always along the, concentration gradient.,  It is comparatively slow process., , circular DNA molecules, a few RNA, molecules, ribosomes and components of, protein synthesis., , , , Found in plant cells and in euglenoides,  Based on the type of pigments plastids can, be classified into chloroplasts, chromoplasts, and leucoplasts.,  The chloroplasts contain chlorophyll and, carotenoid pigments which are responsible, for trapping light energy essential for, photosynthesis.,  In the chromoplasts, fat soluble carotenoid, pigments like carotene, xanthophylls etc. are, present.,  Leucoplasts are colourless plastids that, store food.,  There are three types of leucoplasts,  I) Eliaoplast–stores oil and fat ii), Amylopast–stores starch iii) Aleuroplast –, stores protein,  Chloroplasts of the green plants are found, in the mesophyll cells of the leaves.,  Chloroplasts are double membrane, structures.,  The space limited by the inner membrane of, , the chloroplast is called the stroma.,  A number of organised flattened, membranous sacs called the thylakoids.,  Thylakoids are arranged in stacks like the, piles of coins called grana.,  There are flat membranous tubules called, the stroma lamellae connecting the, thylakoids of the different grana.,  The stroma contains enzymes, double, stranded DNA molecules, ribosomes, ,  Ribosomes are granular structure first, observed by George Palade (1953).,  Non-membranous cell organelles made up of, ribonucleic acid (RNA) and proteins.,  Eukaryotic ribosomes are 80S while the, prokaryotic ribosomes are 70S., , ‘S’ (Svedburg unit)stands for sedimentation, coefficient.(measure of density and size).,  Both 70S and 80S ribosomes consists of two, subunits.,  Primary function is protein synthesis hence, called protein factory of the cell., ,  Function : Site of photosynthesis, and, imparts colours to fruits and flowers., , RIBOSOMES, , NUCLEUS :,  Nucleus as a cell organelle was first, described by Robert Brown in 1831., Prepared by, ,  The interphase nucleus has highly extended, and elaborates nucleoprotein fibres called, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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, , , , , , , , , , , , chromatin., The nucleus also contains nuclear matrix, and spherical bodies called nucleolus., Nucleolus is the site of active ribosomal RNA, synthesis., Nuclear envelope consists of two membranes, –outer and inner with a space between them, called the perinuclear space.,, Minute openings on the nuclear envelop, (Nuclear pore) allow the movement of RNA, and protein in both directions., The nuclear matrix or nucleoplasm contains, nucleolus and chromatin., Chromatin contains DNA and some basic, proteins called histones, some non-histone, proteins and RNA., During cell division the chromatins, condensed to form chromosomes., A single human cell contains approximately, two meter long thread of DNA in 46, chromosomes., Each chromosome essentially has a primary, constriction or the centromere., On each side of centromere there is disc, shaped structures called kinetochores., Based on the position of the centromere, , Prepared by, , , , , , , , , chromosomes are classified into four types., i)Metacentric: centromere at the middle, with two equal arms., ii)Sub-Metacentric: centromere near the, centre with one short arm and one long arm., iii)Acrocentric: centromere near the tip, with one extremely short arm and a very, long arm., iv)Telocentric: with terminal centromere., A few chromosomes have non-staining, secondary constrictions at a constant, location., This gives the appearance of a small, fragment called the satellite., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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CELL CYCLE AND CELL DIVISION,  INTRODUCTION,  Growth and reproduction are characteristics, of living cells.,  The mechanisms of division and, multiplication of cells together constitute, cell reproduction,  The cycles of growth and division allow a, single cell to form a structure consisting of, millions of cells., PHASES OF CELL CYCLE,  The duration of cell cycle can vary from, organism to organism.,  Cell cycle is divided into two basic phases:, Interphase and M phase,  The M Phase represents the phase when the, actual cell division or mitosis occurs and the,  interphase represents the phase between, two successive M phases.,  The M Phase starts with the nuclear division,, corresponding to the separation of daughter, chromosomes known as karyokinesis and, usually ends with division of cytoplasm, G1 PHASE,  G1 phase corresponds to the interval, between mitosis and initiation of DNA, replication.,  Cell is metabolically active and grows in size, but does not replicate its DNA., G2 PHASE,  Cell growth continues.,  Synthesis of RNA and proteins continues, and cell is prepared for mitosis phase.,  G0 PHASE,  Some cells do not show division. E.g. heart, cells.,  Many other cells divide only occasionally to, replace damaged or dead cells., , CELL CYCLE,  Cell division, DNA replication, and cell, growth have to take place in a coordinated, way to ensure correct division and formation, of progeny cells.,  It is the life period of a cell during which a, cell synthesizes DNA (replication), grows in, size and divides into two daughter cells., known as cytokinesis,  The interphase, commonly called the resting, phase, is the time during which the cell is, preparing for division by undergoing both, cell growth and DNA replication in an orderly, manner.,  The interphase is divided into three further, phases:,  G1 phase (Gap 1),  S phase (Synthesis),  G2 phase (Gap 2 ), S PHASE,  During S or synthesis phase, the amount of, DNA per cell doubles, but there is no, increase in the chromosome number.,  In animal cells, during the S phase, DNA, replication begins in the nucleus, and the, centriole duplicates in the cytoplasm., , , , The cells that do not divide further exit G1, phase and enter an inactive stage called, quiescent stage (G0).,  In animals, mitotic cell division is seen only, in the diploid somatic cells.,  In plants mitosis takes place in both haploid, and diploid cells, , MITOSIS,  It is a process of cell division where, chromosomes replicate and get equally, distributed into two daughter cells. Hence, it, is also called equational division.,  The process of mitosis keeps the, chromosome number equal in daughter as, well as parental cell., , Prepared by, ,  Mitosis usually takes place in somatic cells.,  Mitosis is divided into four stages of nuclear, division (Karyokinesis):,  1.Prophase, 2.Metaphase,  3.Anaphase, 4.Telophase, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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1.PROPHASE,  Prophase is the first stage of mitosis, which, follows the S and G2 phases of interphase.,  The centrosome moves towards opposite poles, of the cell.,  Each centrosome radiates out microtubules, called asters., 2.METAPHASE,  Metaphase chromosome is made up of two, sister chromatids, which are held together by, the centromere.,  Small disc-shaped structures, where spindle, fibres attach to the surface of the centromeres, are called kinetochores.,  Chromosomes are arranged at the centre of, ANAPHASE,  Centromere splits and daughter, chromosomes move towards two opposite, poles.,  The centromere of each chromosome is, towards the pole with the arms of the, chromosome trailing behind., , The two asters together with spindle fibres, forms mitotic apparatus.,  Chromosomal material condenses to form, compact mitotic chromosomes.,  Chromosomes are seen to be composed of two, chromatids attached together at the, centromere., , , the cell with the help of spindle fibres.,  This arrangement is called metaphase plate, formation.,  The plane of alignment of the chromosomes at, metaphase is referred to as the metaphase, plate., , , , , , CYTOKINESIS,  Cytokinesis involves the division of cytoplasm, of a cell.,  In animal cells, a furrow develops in the, plasma membrane, which gradually deepens, and ultimately joins in the centre dividing the, cell cytoplasm into two.,  It is achieved in plant cell by cell plate, formation., , TELOPHASE, Chromosomes finally reach their respective, poles., The chromosomes begin to de-condense and, return into a undifferentiated mass., Nuclear envelope assembles around each, chromosome clusters., Golgi bodies and ER complex, which had, disappeared after prophase start to reappear., , , , The formation of the new cell wall begins with, the formation of a simple precursor, called, cell-plate that represents the middle lamella, between the walls of two adjacent cells.,  When karyokinesis is not followed by, cytokinesis, a multinucleated condition, arises. This is called Syncytium.,  Example- liquid endosperm in coconut., , MEIOSIS,  The cell division that reduces the number of chromosome into half and results in the, production of haploid daughter cells..,  It helps in production of haploid phase in the life cycle of sexually reproducing organism.,  It involves following events.,  Two sequential cycles of nuclear and cell division called meiosis I and meiosis II but single, cycle of DNA replication.,  It involves pairing of homologous chromosome and recombination of them.,  Four haploid daughter cells are formed at the end of meiosis II.,  The phases of meiosis are as shown below, , MEIOSIS-I, 1.Prophase I,  It comprises of 5 stages:, LEPTOTENE,  During Leptotene, the chromosome becomes, , Prepared by, , distinct and visible under microscope.,  Compaction of chromosome continues, throughout the leptotene phase., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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, , , , , , , , , , , , , , , , , , , , , ZYGOTENE, Pairing of homologous chromosomes called, synapsis occurs., A pair of synapsed homologous, chromosomes is called bivalent., Synapsis occurs with help of complex, cytochemical substance called, synaptonemal complex., PACHYTENE, Exchange of genetic material between nonsister chromatids of homologous, chromosome occurs (crossing over)., The crossing over is enzyme – mediated, process which involves enzyme recombinase., DIPLOTENE, It is recognized by dissolution of, synaptonemal complex and tendency to, separation of bivalent except at the site of, crossing over., The X-shaped structures formed during, separation are known as chiasmata., DIAKINESIS, Terminalisation of chiasmata can be, observed., By the end of this stage, the nucleolus, disappears and the nuclear envelope breaks., Metaphase I, The bivalents align at the equatorial plate., Microtubules from the opposite poles attach, to the pairs of homologous chromosomes., Anaphase I, The two chromosomes of each bivalent, , Prepared by, , , , , , , , , , , , , , , , , , , separate and move to the opposite ends of, the cells., The sister chromatids are attached to each, other., Telophase, Nuclear membrane and nucleolus reappears, and cytokinesis follows., This is called as diad of the cells., The stage between two meiotic divisions is, called interkinesis and it is short lived, that, follows Meiosis II., MEIOSIS II, Prophase II, The chromosomes begin to condense, accompanied by the dissolution of the, nuclear membrane and the disappearance of, the Golgi apparatus and ER complex., Metaphase II, Chromosomes align at the equator., Spindle fibres attach to kinetochores of, sister chromatids at each pole., Anaphase II, Chromatids separate by splitting of, centromere., As a result, chromatids move towards their, respective poles in the cell., Telophase II, The two groups of chromosomes get, enclosed by a nuclear envelope., Cytokinesis follows resulting in the, formation of tetrad of cells i.e., four haploid, daughter cells., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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TRANSPORT IN PLANTS, , , , , , , , , , , , , , , , , , , , , , , , , , , WATER POTENTIAL (Ψ), It is a concept fundamental to the, understanding of water movement., Water potential is determined by solute, potential (Ψs) and pressure potential (Ψp)., Water molecules possess kinetic energy., The greater the concentration of water in the, system, the greater is its kinetic energy or, water potential., So pure water has greatest water potential., Water potential is denoted by Greek symbol, Psi (Ψ) and is expressed in pressure unit, Pascal (Pa)., Water pressure of pure water is taken as zero, at standard temperature and pressure., A solution has less water potential due to less, water concentration., The magnitude of lowering of water potential, due to dissolution of solute is called solute, OSMOSIS, The plant cell is surrounded by a cell, membrane and a cell wall., The cell wall is freely permeable to water, and substances in solution hence is not a, barrier to movement., In plant cells, the cell membrane and the, membrane of the vacuole, the tonoplast, together are important determinants of, movement of molecules in or out of the cell., Osmosis is the diffusion of water across a, semi-permeable membrane. ., The net direction and rate of osmosis, depends upon the pressure gradient and, concentration gradient., ater will move from its region of higher, concentration to region of lower, concentration until equilibrium is reached., Solute A has more water and less solutes so, high water potential in comparison to the, solution in B container., Osmosis is demonstrated by Thistle funnel, experiment., Semi permeable membrane fixed at mouth, region of thistle funnel separates pure water, in the beaker and concentrated solution in, the funnel., Water in the beaker will move into the funnel,, resulting in rise in the level of the solution in, Prepared by, , potential.,  Solute potential is always negative. More the, solute molecules in the solution lesser the, solute potential.,  For a solution at atmospheric pressure, (water potential) Ψw = (solute potential) Ψs .,  If a pressure greater than atmospheric, pressure is applied to pure water or, solution, its water potential increases.,  Pressure can build up in a plant, system,when water enters a plant cell due to, diffusion. it makes the cell turgid.,  Pressure potential is usually positive., Pressure potential is denoted as (Ψp).,  Water potential of a cell is affected by both, solute and pressure potential.,  The relationship between them is as follows:, Ψw = Ψs + Ψp, the funnel., , ,  This will continue till the equilibrium is, reached.,  External pressure can be applied from the, upper part of the funnel such that no water, diffuses into the funnel through the, membrane.,  This pressure required to prevent water, from diffusing is the osmotic pressure.,  It is the function of the solute, concentration(osmotic potential), more the, solute concentration, greater will be the, pressure required to prevent water from, diffusing in.,  Numerically osmotic pressure is equal to, osmotic potential but sign is opposite.,  Osmotic pressure is the positive pressure, while osmotic potential is negative, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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PLASMOLYSIS,  The behaviour of the plant cells with regard to, water movement depends on the surrounding, solution,  If the surrounding solution balances the, osmotic pressure of cytoplasm, the solution is, called, isotonic.,  If the external solution is more dilute than, cytoplasm, it is hypotonic and If the external, solution is more concentrated than, cytoplasm, it is hypertonic.,  Cells swell in hypotonic solutions and shrink, in hypertonic ones.,  Plasmolysis is the shrinkage of the cytoplasm, of the cell away from its cell wall under the, influence of hypertonic solution.,  When the cell is placed in an isotonic, solution, there is no net flow of water towards, , , , , , , , , the inside or outside., The process of plasmolysis is usually, reversible., When the cells are placed in a hypotonic, solution (higher water potential or dilute, solution as compared to the cytoplasm),, water diffuses into the cell causing the, cytoplasm to build up a pressure against the, wall, that is called turgor pressure., The pressure build up against the wall due, to movement of water inside is called turgor, pressure., The pressure exerted by the protoplasts due, to entry of water against the rigid walls is, called pressure potential Ψp, It is responsible for enlargement and, extension growth of cells, , IMBIBITION,  Imbibition is a special type of diffusion when, water is absorbed by solid (colloids) causing, them to increase in volume.,  For example absorption of water by seeds, and dry woods.,  Imbibition is the initial step in seed, germination.,  Imbibition is also a kind of diffusion, , because movement of water is from higher, concentration to lower concentration.,  Water potential gradient between the, absorbent and liquid imbibed is essential for, imbibition.,  For any substance to imbibe any liquid,, affinity between the adsorbant and the, liquid is also a pre-requisite., , ABSORPTION OF WATER,  Water is absorbed along with mineral, solutes by root hairs by diffusion.,  Root hairs are thin-walled slender, extensions of root epidermal cells that, greatly increase the surface area for, absorption., 1.apoplast pathway 2.symplast pathway, APOPLAST AND SYMPLAST PATHWAY, , , , , , , endodermis in the roots., The inner boundary of cortex, endodermis is, impervious to water due to suberised matrix, called Casperian strip., The apoplastic movement of water occurs, exclusively through the intercellular spaces, and the walls of the cells., Movement through the apoplast does not, involve crossing the cell membrane., The apoplast does not provide any barrier to, ,  The apoplast is the system of adjacent cell, , walls, that is continuous throughout the, plant, except at the casparian strips of the,  water movement and water movement is through mass flow., , , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 The symplastic system is the system of, interconnected protoplasts.,  Neighbouring cells are connected through, cytoplasmic strands that extend through, plasmodesmata.,  During symplastic movement, the water, travels through the cells–their, cytoplasm;intercellular movement is through, the plasmodesmata.,  Endodermis prevents water or any solutes, dissolved in water from passing through the, layer via apoplastic pathway.,  Water can pass through the endodermis by, crossing the membrane of the endodermis.,  That is water moves through the symplast, and crosses a membrane to reach the cells of, the xylem., , TRANSPIRATION PULL, ,  Water is mainly ‘pulled’ through the plant body, due to driving force of transpiration from the, leaves.,  It is termed as cohesion – tension –, transpiration pull model of water transport.,  Transpiration is evaporative loss of water from, plant leaves.,  It occurs mainly through stomata (sing. :, stoma).,  Besides the loss of water vapour in, transpiration, exchange of oxygen and carbon, dioxide in the leaf also occurs through these, stomata.,  Normally stomata are open in the day time and, close during the night.,  The opening and closing of stomata is because, of turgidity of guard cells.,  The inner wall of each guard cell, towards the, pore or stomatal aperture,is thick and elastic.,  When turgidity increases within the two, guard cells flanking each stomatal aperture, or pore, the thin outer walls bulge out and, force the inner walls into a crescent shape.,  When the guard cells lose turgor, due to, water loss, the elastic inner walls regain, their original shape, the guard cells become, flaccid and the stoma closes,  Transpiration is affected by several external, factors: temperature, light, humidity, wind, speed.,  Plant factors that affect transpiration, include number and distribution of stomata,, per cent of open stomata, water status of the, , Prepared by, ,  The movement of water through the root, layers is ultimately symplastic in the, endodermis.,  Some plants have additional structures, associated with roots that help in water and, mineral absorption,  A mycorrhiza is the symbiotic association, between a fungus and angiospermic roots.,  The fungal filaments forms a network, around the young root to have large surface, area that help to absorb mineral ions and, water from the soil.,  The fungus provide minerals and waters and, roots in turn provide organic and nitrogen, containing compounds.,  Pinus seeds cannot germinate and establish, without the presence of mycorrhizae., plant, canopy structure etc.,  The transpiration driven ascent of xylem sap, depends on physical properties of water,, which are as follows:,  Cohesion – mutual attraction between, water molecules.,  Adhesion – attraction of water molecules to, polar surfaces (such as the surface of, tracheary elements).,  Surface Tension – water molecules are, attracted to each other in the liquid phase, more than to water in the gas phase.,  These properties give water high tensile, strength, i.e,(an ability to resist a pulling, force) and, high capillarity, i.e., the ability to rise in, narrow tubes.,  In plants capillarity is aided by the small, diameter of the tracheary elements – the, tracheids and vessel elements.,  The process of photosynthesis requires, water and the system of xylem helps in the, supply of water from roots to leaf veins.,  During this process, the evaporation of, water takes place via stomata, thin film of, water result in pulling effect in leaves from, xylem.,  Because of lower concentration of water, vapor in atmosphere in comparison to substomatal cavity and intercellular spaces,, water gets diffused in the surroundings and, creates a “Pull ”., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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MINERAL NUTRITION, , CRITERIA FOR ESSENTIALITY, ,  The criteria for essentiality of an element are, given below:,  The element must be absolutely necessary, for supporting normal growth and, reproduction. In the absence of the element, the plants do not complete their life cycle.,  The requirement of the element must be, specific and not replaceable by another, element..,  The element must be directly involved in the, metabolism of the plant.,  Based upon the above criteria only a few, elements have been found to be absolutely, essential for plant growth and metabolism.,  These elements are further divided into two, broad categories based on their quantitative, requirements. (i) Macronutrients, and (ii), Micronutrient,  Macronutrients are generally present in, plant tissues in large amounts (in excess of, 10 mmole Kg –1 of dry matter).,  The macronutrients include carbon,, hydrogen, oxygen, nitrogen, phosphorous,, sulphur, potassium, calcium and, magnesium., , NITROGEN METABOLISM, ,  Micronutrients or trace elements, are, needed in very small amounts (less than 10, mmole Kg –1, , , , , , , , , , for both Rubisco and PEPcase.,  Some essential elements can alter the, osmotic potential of a cell. Potassium plays, an important role in the opening and closing, of stomata., , , , , , , , , 2,  Nitrogen is the most prevalent, element in, living world along with C, H and O.,  It is the main constituent of proteins,, nucleic acids,, 2 fats, hormones, enzymes etc.,  Nitrogen exists as two nitrogen atoms joined, , Prepared by, , of dry matter)., These include iron, manganese, copper,, molybdenum, zinc, boron, chlorine and, nickel., Essential elements can also be grouped into, four broad categories on the basis of their, diverse functions., Essential elements as components of, biomolecules and hence structural elements, of cells (e.g., carbon, hydrogen, oxygen and, nitrogen)., Essential elements that are components of, energy-related chemical compounds in, plants (e.g., magnesium in chlorophyll and, phosphorous in ATP)., Essential elements that activate or inhibit, enzymes, For example- Mg2+ is an activator, , , , , , , by a very strong triple covalent bond (N ≡ N)., The process of conversion of nitrogen to, ammonia is called nitrogen fixation., In nature lightening and ultraviolet, radiation provide energy to convert, atmospheric nitrogen into nitrogen oxide (, NO, NO2 and N2O)., Decomposition of organic nitrogen of dead, plants and animals into ammonia is called, ammonification., Ammonia is first oxidized to nitrite by, bacteria Nitrosomonas or NitrococcUs which, is further oxidized to nitrate with help of, bacteria Nitrobactor., These processes are called nitrification., These nitrifying bacteria are, chemoautotrophs., +, 2NH3+ 3O2 → 2NO + 2H + 2H20, 2N0 - + O2 → 2N0-3, The nitrate thus formed is absorbed by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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plants and is transported to the leaves.,  In leaves, it is reduced to form ammonia, that finally forms the amine group of amino, acids., ,  Nitrate present in the soil is also reduced to, nitrogen by the process of denitrification.,  Denitrificationis carried by bacteria like, Pseudomonas and Thiobacillus., , BIOLOGICAL NITROGEN FIXATION, ,  Reduction of nitrogen to ammonia by living, , organisms is called biological nitrogen, fixation (BNF).,  The enzyme nitrogenase,present in, , prokaryotic organism is capable for nitrogen, , fixation., SYMBIOTIC BIOLOGICAL NITROGEN FIXATION,  Most common symbiotic nitrogen fixation is, observed in Legume-Rhizobium relationship.,  Rhizobium forms root nodules in leguminous , plants, and Frankia produces nitrogen-fixing, root nodules on the roots of non-leguminous, , plants.,  The nodules are small outgrowths on the, roots., ,  Central portion of nodule is pink or red due to, presence of leguminous haemoglobin or, leg- haemoglobin, ,  Both Rhizobium and Frankia are free living in, , soil, but they can fix atmospheric nitrogen, only in a symbiotic association.,  Nodule formation involves sequence of, , interaction between root and Rhizobium as, follows Rhizobia multiply and colonise epidermis of, , roots.,  Root hairs curls and bacteria invade it.,  An infection thread is formed that carries the , bacteria into cortex of root.,  Nodule formation starts in cortex of root.,  Bacteria is released from thread to cells, , Nitrogen fixing microbes (Nitrogen fixers) may, be Aerobic free living bacteria like, Azoospirillum and Beijerinckia, Anaerobic free living forms like Rhodospirillum., Free living cyanobacteria such as Anabaena, and Nostoc, which leads to formation of specialized, nitrogen fixing cells., Nodules establish direct vascular, connection with host for exchange of, nutrients., Nodule contains all necessary biochemical, components like enzyme nitrogenase and leghaemoglobin., Enzyme nitrogenase is a Mo-Fe protein and, catalyses the conversion of atmospheric, nitrogen into ammonia., The reaction is as followsThe enzyme nitrogenase is highly sensitive to, molecular oxygen and needs anaerobic, condition., To protect this enzyme from oxygen, the, nodules contain an oxygen scavenger called, leg- haemoglobin., The ammonia synthesized by nitrogenase, enzyme requires high amount of energy (8, ATP for each NH3 produced)., It is interesting to note that these microbes, live as aerobes under free-living conditions, (where nitrogenase is not operational), but, during nitrogen-fixing events,they become, anaerobic., 4, , , , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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PHOTOSYNTHESIS IN HIGHER PLANTS, , , , , , , , , , , , , , , , SITE OF PHOTOSYNTHESIS, Generally photosynthesis takes place in the, green leaves of plants., The mesophyll cells in the leaves, have a, large number of chloroplasts., Usually the chloroplasts align themselves, along the walls of the mesophyll cells., Chloroplasts are green plastids which, function as the site of photosynthesis in, eukaryotic photoautotrophs., Within the chloroplast there is a, membranous system consisting of grana, the, stroma lamellae and the fluid, stroma., The membrane system is responsible for, synthesizing light energy for the synthesis of, ATP and NADPH., The stroma has enzymes, which are, responsible for the reduction of carbon, PIGMENTS IN PHOTOSYNTHESIS, Pigments are substances that have an, ability to absorb light, at specific, wavelengths., The colour of the leaves is due to four, pigments such as, o Chlorophyll a (bright or blue green in the, chromatogram),, o chlorophyll b (yellow green),, o xanthophylls (yellow) and, o carotenoids (yellow to yellow-orange), Chlorophyll a absorb lights of different, wavelengths and it is the chief pigment ., Absorption spectrum shows the ability of, chlorophyll-a to absorb lights of different, wavelength., , dioxide into carbohydrates and formation of, sugars..,  The reaction in which light energy is, absorbed by grana to synthesis ATP and, NADPH is called light reaction.,  The later part of photosynthesis in which is, reduced to sugar, light is not necessary and, is called dark reaction., , ,  Maximum absorption by chlorophyll a, occurs in blue and red regions of visible, spectrum.,  Major part of the photosynthesis takes place, in the blue and red regions, while some of, the photosynthesis takes place at other, wavelengths also(Action spectrum),  Other thylakoid pigments, like chlorophyll, b, xanthophylls and carotenoids, also, absorb light and transfer the energy to, chlorophyll a. Hence they are called, accessory pigments/antennae molecules.,  These pigments help to make, photosynthesis more efficient by absorbing, different wavelengths of light.,  They also protect chlorophyll a from photooxidation, , LIGHT REACTION,  Light reactions or the ‘photochemical’ phase,  The LHC are made up of hundreds of, include light absorption, water splitting,, pigment molecules bound to proteins.,  Each photosystem has all the pigments, oxygen release, and the formation of high(except one molecule of chlorophyll a), energy chemical intermediates, ATP and, forming a light harvesting system (antennae, NADPH.., molecule).,  The pigments are organised into two discrete, photochemical light harvesting complexes,  The single chlorophyll a molecule forms the, (LHC) within the Photosystem I (PS I) and, reaction centre., Photosystem II (PS II).,  In PS I the reaction centre ,chlorophyll a has an absorption peak at 700 nm, hence is called, P700, while in PS II it has absorption maxima at 680 nm, and is called P680., , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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THE ELECTRON TRANSPORT SYSTEM,  The photosynthetic electron transport chain, electrons are downhill., initiates by the absorbance of light by the,  Electron in the PSI also get excited due to, photosystem-I, light of wavelength 700nm and are, transferred to another accepter molecule,  Reaction centre of photosystem II absorbs, light of 680nm in red region and causing, having a greater redox potential., electron to become excited.,  The electrons then are moved downhill to a,  These electrons are picked by an electron, molecule of energy-rich NADP+ and the, acceptor and pass on to electron transport, addition of these electrons reduces NADP+, system consisting of cytochromes., to NADPH + H+.,  The electrons are passed on to the pigments,  The whole scheme of transfer of electron is, called Z-scheme due to its shape., of photosystem PS I, and the movement of, SPLITTING OF WATER,  In this process the water splits into protons, electrons and oxygen.,  The complex for water splitting is associated with the photosystems-II that is located on the, inner side of the thylakoid membrane.,  Photolysis of water release electrons that provide electron to PS II. Oxygen is also released, during this process., , CYCLIC AND NON-CYCLIC PHOTO-PHOSPHORYLATION,  Phosphorylation is the process through, which, ATP is synthesised by cells (in, mitochondria and chloroplasts) is named, phosphorylation.,  Photophosphorylation is the synthesis of, ATP from ADP and inorganic phosphate in, the presence of light.,  Non-cyclic photophosphorylation is the type, CYCLIC PHOTO-PHOSPHORYLATION,  It is the type of photophosphorylation in, which only PS-I is taking part and the, electron released from the reaction centre, P700 returns to it after passing through a, series of carriers,  The cyclic photophosphorylation takes place, in the stromal lamellae of the chloroplast.,  This happens because the stromal lamellae, CHEMI-OSMOTIC HYPOTHESIS,  This hypothesis was given by Peter Mitchell, (1961) in order to explain the ATP synthesis, in photosynthesis.,  The synthesis of ATP is directly linked to the, development of a proton gradient across the, thylakoid membranes of a chloroplast.,  The development of proton gradient results, due to the reasons given below, (i) As the water molecule splits into the inner, side of the membrane the protons or hydrogen, ions that are produced by the water splitting, gets accumulate within the thylakoids lumen., (ii) Transportation of protons takes place, across the membrane when the electron, Prepared by, , of photophosphorylarion in which both the, photosystems (PS-I and PS-II) cooperate in, light driven synthesis of ATP.,  During this cycle, the electron released from, PS-II does not return to it hence, it is known, as non-cyclic photophosphorylation,  Both ATP and NADPH + H+ are synthesised, by this kind of electron flow., does not possess enzyme NADP reductase, (essential for reducing NADP+ to NADPH), and PS-II.,  The cyclic flow hence, results only in the, synthesis of ATP, but not of NADPH + H+ .,  Cyclic photophosphorylation also occurs, when only light of wavelengths beyond 680, nm are available for excitation., moves through the photosystems.,  The primary acceptor of electron is located, towards the outer side of the membrane,, which transfers electron to the proton (H+), carrier and not to the electron carrier.,  So, this molecule, while transporting an, electron removes a proton from the stroma,, thus, release of proton takes place into the, inner side, i.e., on the lumen of the, membrane.,  (iii) The enzyme NADP reductase is present, on the stromal side of the membrane., , Thus, along with the electrons that comes, from the acceptor of electrons of PS-I,, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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, , , , , , , , protons are also necessary to reduce NADP+, to NADPH + H+, Hence, within the chloroplast, protons in the, stroma decrease in number, while in the, lumen there is accumulation of protons., This creates a proton gradient across the, ATPsynthaase Enzyme, The enzyme ATPsynthase consists of the, following two parts, F0 Particle, This portion remains embedded in the, membrane and forms a transmembrane, channel, which carries out facilitated, diffusion of protons across the membrane., F1 Particle, This portion protrudes towards the outer, surface of the thylakoid membrane which, faces the stroma., Conformational change occurs in F1 particle, , thylakoid membrane as well as a measurable, decrease in pH in the lumen.,  The gradient is broken down due to the, movement of protons across the membrane, to the stroma through the transmembrane, channel of the F0 of the ATPsynthase., of ATPsynthase, which caused due to the, breakdown of the gradient, which allows the, enzyme to synthesise several molecules of, ATP.,  Thus, Chemiosmosis requires a membrane,, a proton pump, a proton gradient and ATP, synthase.,  The ATP thus, produced will be used, immediately in the biosynthetic reaction (in, stroma), responsible for the fixing of CO2, and synthesis of sugar., , CALVIN CYCLE (C3-PATHWAY), , pathway.,  This is a cycle biochemical pathway of, reduction of CO2 or photosynthetic carbon,,  Regeneration is the generation of RuBP, cycle, which was discovered by Melvin Calvin., molecules for the continuation of cycle. This, process require one molecules of ATP.,  The Calvin cycle runs in all photosynthetic, plants, no matter they shows C3, C4 or any,  Hence, for every CO2 molecule that- enters, other pathways., the Calvin cycle, required are 3 molecules of, ATP and 2 molecules of NADPH., Primary Acceptor of CO2 in C3 Pathway,  After a long research and conducting many,  The cyclic phosphorylation takes place in, experiments it was concluded by the scientists, order to meet the difference in the number of, that in C3 pathway, the acceptor molecule is a, ATP and NADPH used in the dark reaction., 5-carbon ketose sugar, i.e., Ribulose Bis,  Thus, in order to produce one molecule of, phosphate (RuBP)., glucose through the Calvin pathway, 18 ATPs,  Calvin cycle can be described under three, and 12 NADPHs are required., stages: carboxylation, reduction and, regeneration.,  Carboxylation is the fixation of CO2 into 3phosphoglyceric acid (3-PGA).,  Carboxylation of RuBP occurs in presence of, enzyme RuBP carboxylase-oxygenase, (RuBisCO) which results in the formation of, two molecules of 3-PGA.,  Reduction is series of reaction that leads to, formation of glucose.,  Three molecules of ATP and two molecules of, NADPH are required for reduction of one, molecules of CO2., .,  Hence, the fixation of 6 molecules of CO2 and, 6 turns of the cycle are required in order to, release one molecule of glucose from the, #############, , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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RESPIRATION IN PLANTS, GLYCOLYSIS,  Glycolysis is a step-wise process by which one, derived from sucrose, undergoes partial, molecule of glucose (6C) breaks down into two, oxidation to form two molecules of pyruvic, molecules of pyruvic acid (3C)., acid.,  The scheme of glycolysis was given by Gustav  In plants this glucose is derived from sucrose, Embden, Otto Meyerhof and J Parnas and is, (end product of photosynthesis) or from, often referred as the EMP pathway., storage carbohydrates.,  e is converted into glucose and fructose by the,  It is a common pathway in both aerobic and, enzyme, invertase, and these two, anaerobic modes of respiration., monosaccharides readily enter the glycolytic,  But in case of anaerobic organisms, it is the, pathway., only process taking place during respiration.,  Glycolysis is the process in which glucose,, , STEPS INVOLVED IN GLYCOLYSIS., , , , , , , , , ,  Glucose and fructose are phosphorylated to, give rise to glucose-6- phosphate by the, activity of the enzyme hexokinase.,  Isomerisation of this phosphorylated glucose6-phsophate takes place to form fructose-6phosphate with the help of an enzyme, phosphohexose isomerase,  This fructose-6-phosphate is again, , phosphorylated by ATP in order to form, fructose 1, 6-bisphosphate in the presence, of an enzyme phosphofructokinase and, Mg2+., Splitting of fructose 1, 6-bisphosphate takes, place into two triose phosphate molecules, i.e.,, dihydroxyacetone, phosphate, and, 3phosphoglyceraldehyde (i.e., PGAL)., Each molecule of PGAL removes two redox, equivalents in the form of hydrogen atom and, transfer them to a molecule of NAD+ (This, NAD+ forms NADH + H+)., Glyceraldehyde 3-phosphate is converted to, 1,3- bisphosphoglyceric acid by the enzyme, glyceraldehyde 3- phosphate dehydrogenase, 1,3-bisphosphoglyceric acid is converted to 3phosphoglyceric acid by the enzyme, phosphoglycerate kinase., 3-phosphoglyceric acid is converted to 2phosphoglycerate by the enzyme, phophoglyceromutase., ,  2-phosphoglycerate is converted to, Phosphoenol Pyruvate(PEP) with the release, of one molecule of water,  Pyruvate kinase converts phosphoenol, pyruvate to pyruvate., , Metabolic Fate of Glycolysis,  ATP is utilised at two steps: first in the, conversion of glucose into glucose 6phosphate and second in the conversion of, fructose 6-phosphate to fructose 1, 6bisphosphate.,  When 3-phosphoglyceraldehyde (PGAL) is, converted to 1, 3-bisphosphoglyceric acid, , Prepared by, , (BPGA), NADH + H+ is formed from NAD+.,  Conversion of 1,3-bisphosphoglycerate to 3phosphoglycerate and phospho-enol pyruvate, to pyruvate, are energy-yielding process,, where energy is trapped by the formation of, ATP.,  The overall reaction of glycolysis can be, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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depicted as, Glucose + 2Pi + 2ADP + 2NAD+ —> 2 Pyruvate + 2ATP + 2NADH+H+,  Two molecules of NADH+H+ on oxidation, produce 6 molecules of ATP. Therefore, a net, gain of 8ATP molecules occurs during, glycolysis.,  There are three major ways in which different, cells handle pyruvic acid produced by, glycolysis.,  These are lactic acid fermentation,, alcoholic fermentation and aerobic, , respiration.,  Fermentation takes place under anaerobic, conditions in many prokaryotes and, unicellular eukaryotes.,  For the complete oxidation of glucose to CO 2, and H2O, organisms follow Krebs’, cycle,which is also called as aerobic, respiration., , FERMENTATION, ,  Fermentation is the incomplete oxidation of, glucose under anaerobic conditions by sets of, reactions.,  Fermentation is of two types,  1.Alcoholic fermentation 2.Lactic acid, fermentation.,  In alcohol fermentation, pyruvic acid is, converted to CO2 and ethanol by pyruvic acid, decarboxylase and alcohol dehydrogenase.,  It is done under two steps,  (а) Pyruvic acid is first de-carboxylated to, acetaldehyde in the presence of enzyme, pyruvic acid decarboxylase.,  (b) This acetaldehyde is further reduced to, ethyl alcohol or ethanol in the presence of, enzyme, i.e., alcohol dehydrogenase.,  During lactic acid fermentation, organisms, like some bacteria produces lactic acid as an, end product from pyruvic acid.,  In some animal cells(muscles during exercise), when oxygen is inadequate for cellular, respiration pyruvic acid is reduced to lactic, acid by lactate dehydrogenase.,  In the alcoholic and lactic acid fermentation,, NADH+H+ is the reducing agent which is, , , , , , , , , , , , oxidized to NAD+., The energy released in both the processes is, not much and the total sum of ATP molecules, produced during fermentation is 2 ATP., In both lactic acid and alcohol fermentation, not much energy is released., i.e., not more than 7% of the energy is, released from glucose and not all of it is, trapped as high energy bonds of ATP., The fermentation processes are proved to be, hazardous in nature because either acid or, alcohol is produced on oxidation., Apart from this, yeasts may also poison, themselves to death if the concentration of, alcohol reaches about 13%., In eukaryotes complete oxidation of glucose, take place within the mitochondria and this, requires O2., Aerobic respiration is the process that leads, to a complete oxidation of organic substances, in the presence of oxygen, and releases CO 2 ,, water and a large amount of energy present, in the substrate., , AEROBIC RESPIRATION, ,  The complete breakdown of glucose molecules, in the presence of oxygen to release energy is, called aerobic respiration.,  For aerobic respiration, pyruvate is, transported from the cytoplasm into the, mitochondria.,  The crucial events in aerobic respiration are:, 1.The complete oxidation of pyruvate by the, stepwise removal of all the hydrogen atoms,, leaving three molecules of CO2 ., 2.The passing on of the electrons removed as, Prepared by, , part of the hydrogen atoms to molecular O2, with simultaneous synthesis of ATP,  First event takes place in the matrix of the, mitochondria while the second process is, located on the inner membrane of the, mitochondria.,  In mitochondria, Pyruvate undergoes, oxidative decarboxylation by a complex set of, reactions catalysed by pyruvic dehydrogenase, with the participation of several coenzymes,, including NAD+ and Co-enzyme A., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 Two molecules of NADH are produced from the metabolism of two molecules of pyruvic acid.,  The acetyl CoA then enters a cyclic pathway, tricarboxylic acid cycle, more commonly called, as Krebs’ cycle after the scientist Hans Krebs who first elucidated it., , TRICARBOXYLIC ACID CYCLE, ,  The TCA cycle starts with the condensation of, acetyl Co-enzyme A with oxaloacetic acid, (OAA) and water to yield citric acid.,  The reaction is catalysed by the enzyme, citrate synthase and one molecule of CoA is, released.,  Citrate is then isomerised to isocitrate.,  It is followed by two successive steps of, decarboxylation, leading to the formation of, α-ketoglutaric acid and then succinyl-CoA.,  In the next step Succinyl-CoA is oxidised to, OAA allowing the cycle to continue.,  During the conversion of succinyl-CoA to, succinic acid a molecule of GTP is, synthesised.This is a substrate level, phosphorylation., ,  In a coupled reaction GTP is converted to, Output of Krebs’ Cycle or Citric Acid Cycle,  During this cycle of reactions, 3 molecules of, , NAD+ are reduced to NADH + H+, and one, molecule of FAD+ is reduced to FADH2., ,  uring this one molecule of ATP is reduced, directly from GTP (by substrate level, phosphorylation)., Pyruvic acid + 4 NAD+ + FAD+ + 2H2O + ADP + Pi, , , , , , , , , , , , GDP with the simultaneous synthesis of ATP, from ADP., , For continuous oxidation of acetyl Co-A,, continued replenishment of oxalo acetic acid is, necessary., In addition to this regeneration of NAD+ from, NADH and FAD+ from FADH2 are also, required., 3CO2 + 4NADH + 4H+ + FADH2 + ATP, At the end, glucose has been broken down to release CO 2 and 8 molecules of NADH+H+, two, FADH2 are synthesised and just two molecules of ATP., ELECTRON TRANSPORT SYSTEM (ETS) AND OXIDATIVE PHOSPHORYLATION, These reactions in the respiratory process are to release and utilise the energy stored in, NADH+H+ and FADH2., The metabolic pathway through which the electron passes from one carrier to another, is called, the electron transport system (ETS) and it is present in the inner mitochondrial membrane., This is accomplished when they are oxidised through the electron transport system and the, electrons are passed on to O2 resulting in the formation of H2O., Electrons from NADH produced in the mitochondrial matrix during citric acid cycle are oxidised, by an NADH dehydrogenase (complex I), and electrons are then transferred to ubiquinone, located within the inner membrane., Ubiquinone also receives reducing equivalents via FADH2 (complex II) that is generated during, oxidation of succinate in the citric acid cycle., The reduced ubiquinone (ubiquinol) is then oxidised with the transfer of electrons to cytochrome, c via cytochrome bc1 complex (complex III)., Cytochrome c is a small protein attached to the outer surface of the inner membrane and acts, as a mobile carrier for transfer of electrons between complex III and IV., Complex IV refers to cytochrome c oxidase complex containing cytochromes a and a3 , and two, copper centres., Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 When the electrons pass from one carrier to another via complex I to IV in the electron, transport chain, they are coupled to ATP synthase (complex V) for the production of ATP from, ADP and inorganic phosphate., OXIDATIVE PHOSPHORYLATION,  When the electrons pass from one carrier to, depends on the nature of the electron donor., another via complex I to IV in the electron,  Oxidation of one molecule of NADH gives rise, transport chain, they are coupled to ATP, to 3 molecules of ATP, while that of one, synthase (complex V) for the production of, molecule of FADH2 produces 2 molecules of, ATP from ADP and inorganic phosphate., ATP.,  The electron transport and movement of,  Although the aerobic process of respiration, protons creates a proton gradient across the, takes place only in the presence of oxygen, the, mitochondrial membrane., role of oxygen is limited to the terminal stage,  The protons are pumped through a, of the process., membrane protein called complex-V.,  The presence of oxygen is vital, since it drives,  This complex consists of two major, the whole process by removing hydrogen from, components, F1 and F0., the system.,  The F1 headpiece is a peripheral membrane,  Oxygen acts as the final hydrogen acceptor., protein complex and contains the site for,  During respiration ,the energy of oxidationsynthesis of ATP from ADP and inorganic, reduction utilised for the phosphorylation and, phosphate., hence the process is called oxidative,  F0 is an integral membrane protein complex, phosphorylation., that forms the channel through which protons, cross the inner membrane.,  The energy derived from the proton pumping, is used for the synthesis of ATP.,  For each ATP produced, 2H+ passes through, F0 from the intermembrane space to the, matrix down the electrochemical proton, gradient.,  The number of ATP molecules synthesised, , , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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PLANT GROWTH AND DEVELOPMENT, PLANT GROWTH REGULATORS,  The plant growth regulators (PGRs) are small,, , simple molecules of diverse chemical, composition.,  Examples- Indole compounds (indole-3, acetic acid, IAA); adenine derivatives (N6furfuryl- amino purine, kinetin), derivatives, , of carotenoids (abscisic acid, ABA); terpenes, (gibberellic acid, GA3); gases (ethylene,, C2H4).,  The PGRs can be broadly divided into two, , groups based on their functions,Plant, growth promoter and Plant growth, inhibitor, PHYSIOLOGICAL EFFECTS OF PLANT GROWTH, 1.Auxins,  The term ‘auxin’ is applied to the indole-3acetic acid (IAA), and to other natural and, , synthetic compounds having certain growth, regulating properties., ,  They are generally produced by the growing, , apices of the stems and roots.,  IAA and indole butyric acid (IBA) have been, isolated from plants(natural) and NAA, (naphthalene acetic acid) and 2, 4-D (2, 4, dichlorophenoxyacetic) are synthetic auxins.,  They help to initiate rooting in stem cuttings,, promote flowering, prevent fruit and leaf drop, at early stages, induce parthenocarpy, , (example- tomato).,  Auxin help to prevent fruit and leaf drop at, early stages but promote the abscission of older, 2.Gibberellins,  All gibberellins are acidic and are denoted as, , GA1, GA2,GA3 …and so on.,  Gibberellic acid (GA3 ) was one of the first, , gibberellins to be discovered.,  Their ability to cause an increase in length of, axis is used to increase the length of grapes, , stalks.,  They help to elongate and improve shape of, fruits, delay senescence,, 3.Cytokinins,  Cytokinins were discovered as kinetin (a, , modified form of adenine, a purine) from the, autoclaved herring sperm DNA., ,  Zeatin is a natural cytokinin isolated from, corn-kernels and coconut milk., , Prepared by, , Plant growth promoters are involved in, growth promoting activities, such as cell, division, cell enlargement, pattern formation., Major growth promoters include auxins,, gibberellins and cytokinin., Plant growth inhibitors are involved in, various growth inhibiting activities such as, dormancy and abscission.Example- abscisic, acid, Ethylene acts as both promoter and, inhibitor, though it is largely an inhibitor of, growth activities., REGULATORS, mature leaves and fruits., Auxin also controls xylem differentiation and, helps in cell division., Auxin promotes apical dominance., In most higher plants, the growing apical bud, inhibits the growth of the lateral (axillary), buds, a phenomenon called apical, dominance., Removal of shoot tips (decapitation) usually, results in the growth of lateral buds. It is, widely applied in tea plantations, hedgemaking., Auxins are widely used as herbicides., Example- 2, 4-D is widely used to kill, dicotyledonous weeds., Spraying sugarcane crop with gibberellins, increases the length of the stem, thus, increasing the yield, Gibberellins also promotes bolting (internode, elongation just prior to flowering) in beet,, cabbages and many plants with rosette habit., Gibberellins also promotes bolting, defined as, internode elongation just prior to flowering, in, beet, cabbages., Natural cytokinins are synthesised in, regions where rapid cell division occurs, for, example, root apices., Cytokinin helps to produce new leaves,, chloroplasts in leaves, lateral shoot growth, and adventitious shoot formation., , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode

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 Cytokinins help overcome the apical, dominance, and, promote, nutrient, 4.Ethylene,  Ethylene is a simple gaseous plant growth, regulator synthesized by tissues undergoing, senescence and in ripening fruits.,  Influences of ethylene on plants include, horizontal growth of seedlings, swelling of the, axis and apical hook formation in dicot, seedlings.,  Ethylene promotes senescence and, abscission of plant organs,and ripening of, fruits.,  It enhances the respiration rate during, ripening of the fruits.This rise in rate of, respiration is called respiratory climactic.,  Ethylene breaks seed and bud dormancy,, initiates germination in peanut seeds,, sprouting of potato tubers.,  Ethylene promotes rapid internode/petiole, 5.Abscisic Acid,  Abscisic acid (ABA) was discovered for its, role in regulating abscission and dormancy.,  ABA inhibits seed germination.,  ABA stimulates the closure of stomata and, increases the tolerance of plants to various, kinds of stresses. Therefore, it is also called, the stress hormone.,  ABA plays an important role in seed, development, maturation and dormancy.,  By inducing dormancy, ABA helps seeds to, withstand desiccation and other factors, unfavourable for growth .,  ABA acts as an antagonist to Gibberellin., , , , , , , , PHOTOPERIODISM, , mobilisation which helps in the delay of leaf, senescence., , , , , , , , , , elongation in deep water rice plants. It helps, leaves/ upper parts of the shoot to remain, above water., Ethylene also promotes root growth and root, hair formation, thus helping the plants to, increase their absorption surface., Ethephon is the most widely used compound, as a source of ethylene in agricultuer., Ethephon in an aqueous solution is readily, absorbed and transported within the plant, and releases ethylene slowly., Ethephon hastens fruit ripening in tomatoes, and apples and accelerates abscission in, flowers and fruits., It promotes female flowers in cucumbers, thereby increasing the yield., , ,  Interaction between Plant Growth, Regulators,  For every phase of growth, differentiation, and development of plants, one or the other, PGR has some role to play.,  These can either act synergistically or, antagonistically.,  Similarly many functions in the plant body, are controlled by more than one planr, growth regulator.Eg. dormancy in seeds/, buds, abscission, senescence, apical, dominance, etc, , certain critical period .Eg. ChrysanthEMUm,, sugarcane,  (ii) Long day plants (LDP) : These plants, begin flowering when the day length exceeds a, critical length.,  The critical duration is different for different, plants.,  (iii) Day neutral plants :These plants can, flower in all possible photoperiods. The day, neutral plants can blossom throughout the, year. e.g., cucumber, cotton, sunflower,, tomato, ################, , The response of plants to periods of day/night, is termed photoperiodism, The effects of photoperiods or daily duration, of light periods (and dark periods) on the, growth and development of plants, especially, flowering is called photoperiodism., The site of perception of light/dark duration, are the leaves., (i) Short day plants (SDP):These plants, initiate flowering when the day, length(Photoperiod) become shorter than a, , Prepared by, , Dowloaded from HSS Reporter, , Ismail Parambath,KKM.Govt.HSS,Orkatteri,Kozhikkode