Page 1 :
gery ars, , Amy k Er, Chapter 07 ~ olution, , origin and evolution of fe forms, , , , The study of history of life forms on farth Le, the study., of Earth is called volutionary Wolony., les Daryan, veho., , cies from pre existing speciok through, , , , , sradual changes. Ch, Dose ent ait | modification’, , , , , , iouanrisiaasiie, Gnigin of a “Spe, , , , Origin of Universe:, , stars, and galazies,, , The Universe or Cosmos is the totality of existence, including planets,, clouds of intergalactic gas, dust and energy. The stud verse is called © Cosmology and, , { origin | of universe isc called | Cosmogeny., found by astronomical, , , , the stud, , , , aRe of Universe is about 15 - 20 billion years,, SE, , , , Estimate, observations, _ Big bang theor, , unt According to this theory,, , unimaginable in physical terms., The universe expanded and temperature came down Hydrogen a, , later, The gases condensed under gravitation and formed galaxies, , tempts to explain the origin of, a singular huge explosion,, , , , , , , proposed by Abbe Lemaitre, in 1931, the universe originated by, , , , Se., , nd helium were formed, , Earth:, In the solar system of Milky Way galaxy, earth was supposed to have been formed about, , 4.5 billion years back., There was no atmosphere in the early earth, , Water vapour, methane, carbon dioxide and ammonia released from molten masses, covered the surface., , The UV rays from sun broke up water into hydrogen and oxygen. The lighter hydrogen, , escaped., ed with ammonia, methane to form water, carbon dioxide etc, , Oxygen combin, The ozone layer formed and as it cooled, the water vapour fell as rain, , - Life originated 500 million years after the origi iLe., about 400 billion years back., Interesting facts, , There are about 100 billion galaxies and each galaxy has stars ranging from ten million, , to 1 trillion. These stars orbit galaxy's center. A supermassive black hole is believed to, ilky Way has a supermassive black, , have in center of most galaxies. Our own galaxy,, , hole in its center.
Page 2 :
origin of life refers to origin of the, many theories are formulated,, , 1, Theory of Special Creation;, es, , This theory is based on conve, created Life by his divine, , Father Suarez., , living org, , tional re!, , - — act of creatio, , i. Allliving organisms t hat we see ti, 0., , ii. Diversity was always the same sin, iii. Earth is about 4000 years old., , Id., All these are strongly challenged during 19", Note: The theory of special creation was, , Cosmozoa or Panspermia theory:, Panspermia theory:, , Ritcher (1865) proposed this theory., Accordin i i, , or g to this theory life came to earth from other heavenly bodies in the form of, resis ant spores called Panspermia or cosmozoa through meteorites., Still some astronomers believe in this theory., , ORIGIN OF LIFE (PR, , , , Nn. This theory has 3 Connotations:, , day are created as such., Ce creation and will be the same in future also., , century., , Abiogenesis or Spontaneous Generation, , , , ligious literature, According to this the, , , , OTOBIOGENESIS), , , , ANIsms., on the earth surface. To explain origin of life, , ory God, , Proposed by Hebrew et_al., and supported by, , According to this Life arose spontaneously from non-living matter or inanimate substance, , like decaying straw, mud etc., , Louis Pasteur disproved the theory of spontaneous generation and gave the scientific, explanation that life originates from pre-existing life. His experiments are popularly called, , ‘Swan necked flask’ experiments., , He showed in __ pre, , , sterilized flask, life did not., , come from killed yeast ., , in another _ flask, , open to_air, new, organisms arose ___from, ‘killed yeast’. Though the, experiments of Louis, Pasteur disproved the, concept of abiogenesis, it, Sor no -ancwer how first, , life form arose on earth., , while, , living..., , , , No microorganisms, appeared even after, days, , ed, , microorganisms, appeared within, , 24hours, , , , , , Yeast containing, broth in flask is, boiled ta starllize, , As broth cools, condensing, water collects and serve as, , , , , , If nack of flask Is later, broken, outside alr carry, , , , , , , , dust trap to filter the Incoming air, , microorganisms into broth, , , , LOUIS PASTEUR'S SWAN NECKED FLASK EXPERIMENT
Page 3 :
SUPPLEMENT j, ainst the conce,, Iss F sd this theory to aero wae mrotieed, |. Theory of Blogenests: [10 = Hi ; living organisms, Og Ct hes r ing to this, living, sous generation of life aio non-living. Francisco Redi, Louls Pasteur, and, from ducted classical experiments to, , ‘of spontanc, ‘i ivi id not, rom pre-exisUing living an b CG ononzatl are the three prominent scientists who € eck ablogenesis of Maggots. Louis, » theory of abiogenesis. Francisco Redi disprove long careaei, ig hala 1 fiments served as a ath blow pt of, , dispr ? :, Pasteur ‘Swan necked flask’ expe, , Spontaneous generation., et, , ancisco Redl propose, , volution (Physicochemical theory): _, Scena ed by Haeckel and developed, , 4, Theory of Chemical E, Haldane (in 1928). The theory, , The modern hypothesis of origin of life was formulat, , independently by A.I. Oparin of Russia (in 1923) and J.B.S., , was summarized by A.I. Oparin in his book ‘The Origin of Life’., , The theory of Chemical Evolution or Oparin-Haldane theory states that:, , i. Life could have originated from pre-existing non-living matter (abiogenetically) some 3.5, ‘billion years ago, in prim ive atmosphere, through a process of chemical evolution., , ii Initial atmosphere of the earth was reducing as there was no free oxygen., , iii, Primitive earth atmosphere made up of CHa, NH3, Hz and Water vapour etc., , iv. Solar radiations, high temperature of the earth and lightening provided energy for, , evolution of molecules., Electrode, , Miller’s Experiment:, , Stanley Miller and Harold Urey, were first to put to test the, Oparin-Haldane theory, in 1953. T¢, * They conducted the experiment pump ~, simulating prebiotic earth, condition using Spark discharge _, apparatus. The spark discharge, ey, , apparatus is made up of closed, system of glass, except, tungsten electrode., , ~ Spark, , , , ==» Water out, —==}-<t— Water in, , Water droplets, , , , , , , Water containing, , Steps:, organic compound, , 1. Evacuated the apparatus., , 2. A mixture of Methane,, Hydrogen and Ammonia were, passed into the apparatus., , Ey, , Boiling water, , , , Liquid in water trap, , , , SPARK DISCHARGE APPARATUS
Page 4 :
The water in the flask was boiled to produce steai, m., , : mixture of gases (CH, a, THe ical disch (CHa, NHs, Ha and H,0 vapour) were circulated and exposed to high, electrical discharge of 75,000 volts that produced temperature of 800°C, , 5, The product formed were cooled and liquefied, , The liquid of U-trap analyzed., , Result:, , Conclusion:, , mber of organi ., , Anu : ganic compounds related to life like several amino acids, fatty acids and urea, were synthesized. OE, were see, , Only 4 amino acus were not found: Alanine, Aspartic acid, Glycine and Glutamic acid., Control experiment conducted without using energy showed no organic compounds., , , , Proves that_in_ pre from the, , , , ic earth simple organic, primitive gases. In similar experiments by others observed the formation of sugars,, bases, pigments and fats. Analysis of Meteorite contents _also have revealed similar, compounds indicating that similar processes are occurring elsewhere in space., , nitrogen, , With limited evidence, the chemical evolution was more or less accepted., , Origin of Organisms:, gin of Organisms: | -- pflulo~, , —, First non-cellular life forms originated about 3 billion years ago- These molecules were like, 3 blleon eS, , RNA, Proteins and polysaccharides with the ability to reproduce their molecules. First, , Cellular life forms evolved about 2000 million years ago. These were probably single-cells., , A number evidences and postulations are in favour of origin of life in aquatic medium and, , that too in{marine environment. The important argument favouring this is:, , i. The intercellular flui i is saJine., , ii. Majority of acellular forms are found in seas., , iii. Living organisms need oxygen, carbon dioxide and light for sustaining life. These factors, are profusely found in the intertidal zones of the sea. Therefore, it is obvious that life, , originated in the inter-tidal zones of the sea and invaded the freshwaters and terrestrial, , areas., , Mile stones in Origin of Life:, , Origin of Universe: 15 -20 billion years, Origin of Earth : 4.5 billion years, ii. Origin of Life: 3.9 - 4 billion years., , iii, First non-cellular forms of life: 3 billion years, iv. First cellular forms of life: 2 billion years
Page 5 :
FVIDENCES OF EVOLUTION, , A several kinds of evidences, , , , , , , established by takin}, jution has taken place can be este, The fact that evo!’ on ha, The evidences COME from MM,, oe evnile ‘ ae ', a Palae atology riggs, y orpholoky { i, =, b Comparative anatomy and mort . hat a. :, « Molecular homology GSS ; be, CERATORS 7, d Biogeography etc, oe ¢ i, preranopon, cal Evidences: ; srt ima, EY, , , , 1. Palacontologi, , , , palacontology is the study of fossils of Exe, , = tits. cocoa, , Fossils are the remains OF impressions, reserved _in, , of past of anisms, , sedimentary rocks., piel dctadle Ghia ree, , , , , , “ARCHAKORTER®, , Significance:, Fossil records serv!, for Organic evolution., Fossils obtained from different earth, , sediments representing different times, different life forms. This shows that ne, , as direct evidence, STEGOSAURUS, , , , BRANCHIOSAURUS, w forms of life have, , of geological period have shown, arisen at different times in the history of earth., impler than present day forms., , e reptiles are, , Earliest life forms were S, ated by Dinosaurs that have become extinct and th, , Mesozoic era was domin, now represented by forms like Crocodiles., , Evidences from Comparative and Anatomy Morphology:, Morphology refers to study of external features; anatomy refers to the internal structures., , The study of morphology and comparative anatomy of organisms provides ample evidences, of evolution. The sources of evidences of evolution from comparative anatomy and, , morphology are the following the following:, a. Homologous structures, , b. Analogous structures, , c. Adaptive radiation, , d. Vestigial organs, , e. Atavism etc.,
