1. TOPIC-EVOLUTIONPREPARED BY-S.ABHISHEKGROUP MEMBERS-AKASHRAJAT SAHOO-03S.ABHISHEK-04PRITHVI PATTANAIKARNAV PATTANAIKCLASS-XBGUIDED BY Mrs. S.TRIPATHY

2. EVOLUTIONThe gradual changes taking place in livingorganisms giving rise tonew organisms due to changes in theirgenetic composition is calledevolution. 3. ACQUIRED and INHERITED TRAITSa. Inherited traits :-Inherited traits are traits in an organism due to changes in thegenetic composition and it can be passed from one generation to thenext and it results in evolution..b. Acquired traits :-Acquired traits are traits which are acquired by an organismduring its lifetime and it cannot be passed from one generation to thenext and it does not result in evolution. 4. DIFFERENCE BETWEEN ACQUIRED andINHERITED TRAITSACQUIREDINHERITEDTRAITSTRAITSi-These are somatic variations. i- These are genetic variations.ii- Acquired traits develop due to theeffects of environmental factors, useand disguise of organs and special(conscious) efforts.ii- Inherited traits develop due toreshuffling of genetic material andmutations.iii- These traits develop throughoutthe lifetime of an individual, and diewith death of that individual.iii- these traits are transferred(inherited) by the parents to theiroffspring. These dont die but arepassed on to the next generation.iv- Example- Learning of dance,music, etc. and muscular body of awrestler.iv- Example- Attached or free earlobeand curly hair. 5. CHARLES DARWIN(1809-1882)Charles Robert Darwin (1809-1882) at the age of 22went around the world in a ship HMS Beagle. Duringis journey he collected a number of fossil, flora andfauna. He conducted various experiment andformulated his hypothesis that evolution took placedue to natural selection. In 1858, by mutualagreement, Darwin and Wallace presented a jointpaper on their theory. Darwin was an accomplishednaturalist and he also explained the role ofearthworms in soil fertility. Darwin didnt noticeMendels work as relevant to his. 6. CONCLUSIONS OF DARWINS THEORY All animals and plants have a natural tendency toproduce offspring The number of offspring is maintained at a constantlevel. Struggle for existence. variation and Heredity. Survival of the fittest. Original of species. Inheritance of useful variations. 7. ORIGIN of LIFE on EARTHA British scientist (he turned Indian citizen later) J.B.S. Haldane(1929) and Russian scientist Oparin (1924) proposed the theoryof origin of life. This theory states that:a) The lighter elements were present at atomic form.b) As the temperature of earth decreased the lighter elementscombined to form the water, methane , ammonia, hydrogenmolecules (H2) and carbon dioxide.c) All these molecules interacted in hot atmosphere of the earthand formed sugar, amino acids, alcohol, fatty acids, etc.d) By further interactions of these biochemicals, some complexorganic molecules were formed.Later on an experiment was conducted by Stanley Miller andHarold Urey in 1953 maintaining the similar atmosphericconditions those were existed on early earth. At the end of theexperiment they found that 15% of the carbon converted tosimple carbon such as amino acids which form the proteins. 8. SPECIATIONSpeciation is the formation of new species from pre-existingspecies. A new species may be formed from thepopulations occurring in different areas of distribution,the process is called allotropic speciation. While when anew species is formed from a fragment of population inthe same area due to mutation, it is called sympatricspeciation. Speciation also depends on type of evolutioni.e. micro-evolution and macro-evolution. 9. MICRO-EVOLUTIONMicro-evolution is the formation of a species due tosmall but significant changes such as a change in geneor gene mutation and gene recombination. Forexample, if the group of beetles in an illustration wehave discussed earlier, splits into two populations anddont breed together can be called two species. It isbecause they will develop some changes in genes forpesticide resistance, high temperature tolerance etc. 10. MACRO-EVOLUTIONMacro-evolution is the development of differentgenera and taxa. For such an evolution a part ofpopulation should by a barrier so that the two sectionsof a population cannot interbreed. 11. CLASSIFICATIONThe arrangements of different organisms into groupsand subgroups based on their physiological,biochemical and anatomical similarities anddissimilarity is called classification. These similarityand dissimilarity are the characteristics present in theorganisms. Characteristics are the details of physicalappearance, physiological and behavioristic featuresof an organism. For example, the presence of fourlimbs is a characteristics feature of human beings andthe process of photosynthesis is an importantcharacter of green plants. 12. ANCESTRAL CHARACTERISTICSThere are some basic characteristics found in allmembers of a large population . These charactersdecide the fundamental differences among differentgroups of organisms. For example, wings are found infish, forming two different groups of animals. 13. DERIVED CHARACTERISTICSThese are the characteristics developed due to theevolutionary changes in ancestral or basic characteristics.Derived characteristics determine the subgroups orsmaller groups of organisms. These characteristics help inthe classification of different organisms into smaller unitsor groups. The presence of similar characteristics indifferent organisms suggest their origin from thecommon ancestor. 14. COMMON CHARACTERISTICS SHAREDBY MOST OF THE LIVING ORGANISMS Cell is the basic unit of life in all organisms. On the basis of presence or absence of well defined nucleus,organisms can be divided into two groups- prokaryotes andeukaryotes. The eukaryotes which have the cells with well definednucleus can be further divided into two groups unicellularand multicellular organisms based on whether they aremade up of a single cell or many cells. The multicellular organisms may have cellular level oforganisms or tissue level of organisms. The multicellularorganisms can also be classified based on whether they cando photosynthesis or not . The multicellular organisms who can do photosynthesis arecalled plants and those who cannot do so are called animals. The multicellular animals can be grouped on the basis ofpresence or absence of skeletons inside the body. 15. Evidences of evolutionThere are a number of common features in differentorganisms which provide evidence to showevolutionary relationship. The mainevidences of evolution are from the studyof:-Homologous organs, Analogous organs and Fossils 16. Homologous organsThe organs which are similar in structure but different infunctions. Eg :- The fore limbs of amphibians, reptiles, birds, andmammals have similar structures but different functions. Frog(amphibian) uses its fore limb to raise the front of the body. Lizard(reptile) uses its fore limb for walking and running. Birds forelimbs are modified as wings for flying. Mammals use the forelimbs for grasping, walking, running, swimming, flying etc. Thisshows evolutionary relationship. 17. ANALOGOUS ORGANSThe organs which are different in structuresbut similar in functions.Eg :- The wings of butterfly, bird and bat havedifferent structures but similar functions. Thisshows evolutionary relationship. 18. FOSSILSThe remains of organisms which lived long agoare called Fossils . From the study of fossilswe can know their structures and the timeperiod in which they lived. The fossils ofcomplex and recent organisms are foundcloser to the surface of the earth and thefossils of simpler organisms are found deeperinside the earth. The age of fossils can bedetermined by Radio Carbon Dating. The studyof fossils show evolution of simpler forms intocomplex forms and their evolutionaryrelationship. 19. Tree trunk fossil Fish fossil (Knightia)Ammonite Invertebrate Trilobite Invertebrate Dinosaur skull - Rajasaurus 20. TYPES OF FOSSILSTrilobite- It is a Paleozoic arthropod with trilobeddorsal plates, joint appendages and a pair ofantennae.1. Ammonite It is a spirally coiled shelled mollusewhich underwent mass scale extinction alongwith dinosaurs.2. Rajasaurs- The Rajasaurs (dinosaurs) skull wasfound only a few years ago in the Narmada Valley. 21. EVOLUTION by STAGESComplex organisms and its organs developed fromsimpler organisms gradually over generations.i) Evolution of eyes :- The eyes of planaria are just eyespots to detect light. It developed gradually into acomplex organ in higher animals.ii) Evolution of feathers :- Feathers were firstdeveloped in dinosaurs and used for protection fromcold. Later birds used them for flying.iii) Evolution by artificial selection :- Humans cultivatedwild cabbage for over 2000 years and produceddifferent vegetables from it by artificial selection.Eg :- Cabbage by selecting short distance betweenthe leaves.Cauliflower by selecting sterile flowers.Kale by selecting large leavesKohlrabi by selecting the swollen stemBroccoli by arresting flower growth 22. Embryology 23. Evolution should not be equated with progressEvolution has not resulted in progress. Evolution has resulted inthe formation of several complex species from simpler speciesdue to variations, genetic drift and natural selection. This does notmean that one species gets eliminated when new species areformed or that the new species are better than the older species.Species get eliminated only if they are not able to adapt to thechanges in the environment. Several species which could adapt tothe changes in the environment still continue to survive forexample bacteria. Human beings have not evolved fromchimpanzees. They had a common ancestor from which theyevolved separately. Human beings are not the pinnacle ofevolution but they are only one species among the severalevolving species. 24. Human evolution :- (Homo sapiens) There is a great diversity among human beingsin their form and features around the world.Human beings evolved in Africa. Some of themstayed there and others migrated to differentparts of the world. Then due to genetic variationsand the environmental changes in differentgeographical regions they developed changes intheir forms and features.