{"id":18375,"date":"2019-12-06T11:16:41","date_gmt":"2019-12-06T05:46:41","guid":{"rendered":"https:\/\/www.cbselabs.com\/?p=18375"},"modified":"2021-09-18T15:15:47","modified_gmt":"2021-09-18T09:45:47","slug":"important-questions-for-class-12-biology-cbse-the-origin-of-life-and-evidences-of-evolution","status":"publish","type":"post","link":"https:\/\/www.cbselabs.com\/important-questions-for-class-12-biology-cbse-the-origin-of-life-and-evidences-of-evolution\/","title":{"rendered":"Important Questions for CBSE Class 12 Biology The Origin of Life and Evidences of Evolution"},"content":{"rendered":"
1.<\/strong>The study of history of life forms on earth is called evolutionary biology<\/strong>.<\/p>\n 2.Evolution<\/strong> is a process that results in heritable changes in population spread over many generations leading to diversity of organisms on earth.<\/p>\n 3.Origin of life<\/strong> is considered a unique event in the history of universe. (ii)The earth<\/strong> was supposed to have been formed about 4.5 billion years back in the\u00a0solar system of the milkyway galaxy.<\/p>\n 4.Theories of origin of life<\/strong> were given by different thinkers and scientists. (iv)Theory of chemical evolution or Oparin-Haldane theory<\/strong> states that life originated from pre-existing non-living organic molecules and that formation of life was preceded by chemical evolution. 5.Miller\u2019s experiment<\/strong> provided experimental evidence for chemical evolution. 6.Origin of First Cell<\/strong> 7.Evidences of evolution<\/strong> come from (i)Palaeontology<\/strong> is the study of fossils. The fossils are the remains of past organisms\u00a0preserved in sedimentary rocks<\/p>\n (ii)Comparative anatomy<\/strong> and morphological<\/strong> evidences show the similarities and\u00a0differences among the organisms of today and those that existed years ago. For example, human DNA differs in only 1.8% of its base pairs from chimpanzee DNA and there is no difference between the two in the amino acid sequence for the protein cytochrome-c. III.Convergent evolution<\/strong> is development of similar adaptive functional structures in unrelated groups of organisms. Examples are:<\/p>\n (i) Wings of insect, bird and bat.<\/p>\n (ii) Spiny anteater and scaly anteater belong to different orders of class-Mammalia. They have acquired similar adaptations for food, e.g. leg ants, termites and insects.<\/p>\n (v) Embryological evidences Study of comparative embryology shows common patterns of development.<\/p>\n For example, during the life history, frog\u2019s tadpole larva resembles fishes, the ancestors of amphibia.The presence of gill clefts in all vertebrate embryos including human provides a strong evidence in support of organic evolution.<\/p>\n (vi)Anthropogenic evidences Excess use of herbicides, pesticides, etc has resulted in selection of resistant varieties in a lesser time scale. This is also true for microbes against which antibiotics or drugs have been used. All these evidences tell us that \u2018Elvolution is a stochastic process based on chance events in nature and chance mutation in the organisms\u2019.<\/p>\n 1.Why are analogous structures a result of convergent evolution?[All India 2014]<\/strong> 2.Name the type of evolution that, has\u00a0resulted in the development of structures like wings of butterfly and bird. What are such’structures Called?\u00a0 [Delhi 2014 C]<\/strong> 3.State the significance of the study of\u00a0fossils in evolution. \u00a0[Delhi 2012]<\/strong> 4.State the significance of biochemical similarities among diverse organisms in evolution.[Delhi 2012]<\/strong> 5.Write the similarity between the wing of a butterfly and the w*ng of a bat. What do\u00a0you infer from the above, with reference to evolution?[Delhi 2012]<\/strong> 6.Name the scientist who disproved spontaneous generation theory.[Delhi 2010]<\/strong> 7.Why are wings of butterfly and wings of bat called analogous?[Delhi 2009]<\/strong> 8.Mention the type of evolution that has brought the similarity as seen in potato tuber and sweet potato.[Delhi 2009]<\/strong> 9.Are the thorn of Bougainvillea and\u00a0tendrils of Cucurbita homologous or analogous? What type of evolution has brought such a similarity in them? \u00a0 [HOTS; Delhi 2009]<\/strong> 10.Name any two vertebrate body parts\u00a0that are homologous to human forelimbs. \u00a0 [All India 2008]<\/strong> 11.Name the placental mammals corresponding to the Australian spotted Cuscus and Tasmanian tiger cat, which have evolved as a result of convergent evolution.[All India 2008 C]<\/strong> 12.Identify the following pairs as homologous of analogous organs:<\/strong> 13.What was proposed by Oparin and\u00a0Haldane on origin of life? How did SL Miller’s experiment support their proposal? [Foreign 2014]<\/strong> 14.List the two main propositions of\u00a0Oparin and Haldane.\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 [All India 2013]<\/strong> 15.Write the Oparin and Haldane’s hypothesis about the origin of life on earth. How does meteorite analysis favour this hypothesis? [All India 2013]<\/strong> 16.Write about the ancestry and evolution of bat, horse and human on the basis of a comparative study of their forelimbs. What are these limbs categorised as? [Delhi 2013c]<\/strong> 17.Divergent evolution leads to homologous stmctures. Explain with the help of an example.[All India 2011 C]<\/strong> 18.Convergent evolution leads to analogous stmctures. Explain with the help of an example. [All India 2011 c]<\/strong> 19.Mention the contribution of SL Miller’s experiments to origin of life.[Delhi 2010]<\/strong> 20.Why are wings of butterfly and birds said to be analogous organs? Name the type of evolution the analogous organs are a result of. [Foreign 2010]<\/strong> 21.What is adaptive radiation? How did\u00a0Darwin explained this process of evolution? [Delhi 2008 C]<\/strong> 22.(i) Explain adaptive radiation with\u00a0the help of suitable example.<\/strong> 23.Given below is a diagrammatic representation of the experimental set-up used by SL Miller for his experiment<\/strong> 24.State the theory of biogenesis. How does Miller’s experiment support this theory?[Delhi 2012]<\/strong> 25.Convergent evolution and divergent evolution are the two concepts explaning organic evolution. Explain each one with the help of an example.[Foreign 2011; Delhi 2010]<\/strong> 26.Explain adaptive radiation and convergent evolution by taking example of some of Australian marsupials and Australian placental mammals. [Foreign 2010]<\/strong> 27.Anthropogenic action hasten evolution. Explain with the help of suitable<\/strong> 28.(i) Mention the specific geographical region, where these organisms are found.<\/strong> 29.(i)Write your observations on the variations seen in the Darwin’s finches shown\u00a0below.<\/strong> 30.The study of<\/strong> Evolution\u00a0Important Questions for CBSE Class 12 Biology The Origin of Life and Evidences of Evolution 1.The study of history of life forms on earth is called evolutionary biology. 2.Evolution is a process that results in heritable changes in population spread over many generations leading to diversity of organisms on earth. 3.Origin of life is considered …<\/p>\n","protected":false},"author":27,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[2],"tags":[],"yoast_head":"\n
\n(i)The Universe<\/strong><\/p>\n\n
\n
\n(i)Theory of special creation<\/strong> states that God created life by his divine act of creation.
\n(ii)Theory of panspermia\/cosmozoic<\/strong> theory, given by early Greek thinkers states that the spores or panspermia came from outer space and developed into living forms.
\n(iii)Theory of spontaneous generation<\/strong> states that life originated from decaying and rotting matter like straw, mud, etc.<\/p>\n\n
\nThe conditions on the earth that favoured chemical evolution were very high temperature, volcanic storms and reducing atmosphere that contained CH4<\/sub>,NH3<\/sub>, water vapour, etc.<\/p>\n
\n(i)The experiment was carried out by SL Miller and HC Urey in 1953.
\n(ii)He took a closed flask containing CH4<\/sub>,H2<\/sub>,NH3<\/sub> and water vapour at 800\u00b0C and created electric discharge. These conditions were similar to those in primitive atmosphere.
\n(iii)After a week, formation of amino acids were observed. Complex molecules like sugars, nitrogen bases, pigments and fats were seen in the flask by other scientist.
\n(iv)Analysis of the meteorite also revealed the presence of similar compounds.
\n(v)Chemical evolution of life was more or less accepted.
\n<\/p>\n
\n(i)First non-cellular life forms originated three million years ago.
\n(ii)These molecules were like RNA, protein and polysaccharides.
\n(ii)Cellular life form first evolved about 2000 million years ago.
\n(iv)These were single-celled formed in aquatic environment.
\n(v) This form of abiogenesis, i.e. the first form of life arose slowly through evolutionary\u00a0forces from non-living molecules It is accepted by many scientists.<\/p>\n
\n(i) Palaeontology\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (ii) Comparative anatomy and morphology
\n(iii) Biochemical\/Physiology\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 (iv) Biogeography
\n(v) Embryology<\/p>\n\n
\nThe evidences come from comparative study of external and internal structure.
\nI.(a) The organs with same structural design and origin but different functions are called homologous<\/strong> organs.<\/strong> Examples are forelimbs of some animals like whales, bats and cheetah have similar anatomical structure, such as humerus, radius, ulna, carpals, metacarpals and phalanges.
\n(b)Homology<\/strong> in organ indicates common ancestry.
\n(c)Other examples of homology are vertebrate hearts or brains. In plants also, thorns and tendrils of Bougainvillea and Cucurbita represent homology.
\n(d)Homology is based on divergent evolution. The same structure developed along different directions due to adaptations to different needs. The condition is called divergent evolution.<\/strong>
\n
\nII.(a) Organs which are anatomically different but functionally similar are called analogous organs. For example, wings of butterfly and birds.
\n(b)Analogy refers to a situation exactly opposite to homology.
\n(c)Analogous organs are a result of convergent evolution. It is the evolution in which different structures evolve for same function and hence, have similarity.
\n(d)Other examples of analogy are eyes of Octopus and mammals; flippers of penguins and dolphins. In plants, sweet potato (root modification) and potato (stem modification)
\n
\nIII.Vestigial organs<\/strong> like homologous organs provide evidences for organic evolution.
\nThese are degenerate, non-functional and rudimentary organs to the possessor, while correspond to fully developed and functional organs of related organisms.
\n(a)There are about 90 vestigial organs in the human body. Same of them are tail bone (coccyx), wisdom teeth, nictitating membrane, vermiform appendix, etc.
\n(b)Some examples from other animals are hip girdles and bones of the hind limbs in some whales and certain snakes and wings of flightless birds.
\n(iii)Biochemical Evidences<\/strong><\/p>\n\n
\n(iv)Biogeographical evidences The species restricted to a region develop unique features. Also, species present in far separated regions show similarity of ancestry.
\nThis can be explained with the help of following processes:
\nI.Adaptive radiation<\/strong> is an evolutionary process in which an ancestral stock gives rise to new species adapted to new habitats and new ways of life. Examples are
\n(i) Darwin\u2019s finches<\/strong> These were small black birds, which Darwin observed in Galapagos island.<\/p>\n\n
\n(ii)Marsupials of Australia<\/strong> A number of marsupials, different from each other evolved from an ancestral stock, all within the Australian island continent.
\nII.Parallel evolution<\/strong> refers to independent development of similar characters in two animal groups of common ancestry living in similar habitats of different continents. Examples are
\nMarsupial mammals in Australia<\/strong> show parallel evolution as they have evolved from placental mammals. All these closely resemble and look similar to a corresponding marsupial.
\nFew examples are mentioned in the table.
\n<\/p>\n\n
Previous Year\u00a0Examinations Questions<\/span>
\n 1 Mark Questions<\/span><\/h3>\n
\nAns<\/strong>.When two species have structures that are\u00a0similar in function but differ in origin and anatomy are called analogous structures. This is because both move from different areas to a habitat where they adapt themselves accordingly, therefore it is called convergent evolution.<\/p>\n
\nAns<\/strong>.Convergent evolution has resulted in the\u00a0development of structures like wings of butterfly and bird and such structures are called analogous organs.<\/p>\n
\nAns<\/strong>.Fossils help us to know the morphological\u00a0details of the organisms in the past and relate them to the organisms in the present for understanding the process of evolution. We can also trace the time at which the organism existed.<\/p>\n
\nAns.<\/strong>Similarities in biochemicals such as DNA, helps in deriving the line of evolution. Organisms with more similar DNA sequences are considered close relatives or have evolved from the same ancestor,<\/p>\n
\n or<\/strong>
\n Comment on the similarity between the wings of a cockroach and the wings of a bird. What do you infer from the above, with reference to evolution? \u00a0[All India 2012]<\/strong>
\n or<\/strong>
\n Comment on the similarity between the flippers of dolphin and penguins, with reference to evolution.\u00a0\u00a0\u00a0 [Foreign 2012,2009]<\/strong>
\nAns<\/strong>.Similarity between the wings of both the\u00a0organisms is that they perform similar functions. They are thus, analogous organs. With reference to evolution, it can be inferred that these are result of convergent evolution<\/p>\n
\nAns<\/strong>.Louis Pasteur disproved the spontaneous\u00a0generation theory.<\/p>\n
\nAns<\/strong>.They are called analogous because they\u00a0perform similar functions, but are dissimilar in their development and basic structure.<\/p>\n
\nAns.<\/strong>Convergent evolution has bought the\u00a0similarity as seen in potato tuber and sweet potato.<\/p>\n
\nor<\/strong>
\nAre the wing of a bird and the forelimb of a horse homologous or analogous? Name the type of evolution that explains the development of such structures.[Foreign 2009]<\/strong>
\nAns<\/strong>.They are homologous. Divergent evolution has brought this similarity in them<\/p>\n
\nAns<\/strong>.Wings of birds and forelimbs of horses are\u00a0homologous to human forelimb.<\/p>\n
\nAns<\/strong>.Australian spotted cuscus – Lemur\u00a0Tasmanian tiger cat – Bob cat.<\/p>\n2 Marks Questions<\/span><\/strong><\/h3>\n
\n (i)Sweet potato and potato.<\/strong>
\n (ii) Eye of Octopus and eye of mammals.<\/strong>
\n (iii)Thoms of Bougainvillea and ‘ tendrils of Cucurbits.<\/strong>
\n (iv)Forelimbs of bat and whale.[Delhi 2014]<\/strong>
\nAns<\/strong>.The given pairs are identified as
\n(i) Analogous organs.
\n(ii) Analogous organs.
\n(iii) Homologous organs.
\n(iv) Homologous organs.<\/p>\n
\nAns<\/strong>.Oparin and Haldane proposed that life originated on earth sponataneously from non-living matter, i.e. organic molecules. SL Miller conducted an experiment where he created conditions similar to primitive atmosphere, in laboratory such as high temperature, reducing atmosphere
\nconsisting of CH4<\/sub>, NH3<\/sub>, etc. When he created a electric discharge in the flask containing all of these at 800\u00b0C. Organic molecules, e.g. amino acids were formed. This supports the above hypothesis that life could have originated from organic matter.<\/p>\n
\nAns.<\/strong>Two main propositions of Oparin and Haldane were
\n(i) The primitive atmosphere was reducing,
\ni.e.free oxygen was absent.
\n(ii) There was high temperature, high methane, ammonia and hydrogen gas in the atmosphere.<\/p>\n
\nAns<\/strong>.Oparin-Haldane theory states that origin of\u00a0life is the result of a long series of physicochemical changes, brought about first by chemical evolution and then by biological evolution.
\nAnalysis of meteorites also revealed the presence of similar compounds as found in the atmosphere, indicating occurrence of similar processes else where in space.<\/p>\n
\nAns<\/strong>.Bat, horse and human (all mammals) share\u00a0similarities in the pattern of bones of forelimbs. Though these forelimbs perform different function in these animals, they have similar anatomical structure, i.e. all of them have humerus, radius, ulna, carpals, metacarpals and phalanges in their forelimbs.<\/p>\n
\nAns<\/strong>.Divergent evolution is a process where the same structure develops along different directions in different organisms due to adaptations to different needs.\u00a0Divergent evolution leads to homologous structures, as they all have similar anatomical structure and origin, but perform different functions.
\nExamples, the thorn of Bougainvillea and tendrils of Cucurbita are homologous organs as both of them are modified stem which perform different functions.<\/p>\n
\nAns<\/strong>.Convergent evolution is a process of evolution, where anatomically dissimilar structures in different organisms perform similar functions.
\nIt leads to analogous structures, in different group of organisms as they perform similar function, but are anatomically different,Example, potato (stem modification) and sweet potato (root modification), flippers of penguins and dolphins<\/p>\n
\nAns<\/strong>.SL Miller’s experiment provided experimental evidence for chemical evolution. Result of the experiment showed that the first non-cellular forms of life were created about three million years ago. Experiment also demonstrated that non-cellular biomolecule exist in the form of DNA, RNA, polysaccharides and proteins.<\/p>\n
\nAns.<\/strong>Wings of butterfly and birds are analogous structures because they are morphologically different but performs same function.i.e, flying. It occurs due to convergent evolution.<\/p>\n
\nAns<\/strong>.Adaptive radiation is the process of\u00a0evolution of different species in a given geographical area starting from a point and radiating to other habitats.Darwin went to Galapagos islands and observed that there were many varieties of finches in the same island. All the varieties evolved on the island itself. Darwin reasoned that after originating from a common ancestral seed eating stock, the finches must have radiated to different geographical areas and undergone adaptive changes in their beaks enabling some to become insectivorous.<\/p>\n
\n (ii)Cite an example where more than one adaptive radiations have occurred in an isolated geographical area. Name the type of evolution your example depicts and state why it is so named?\u00a0[All India 2014]<\/strong>
\nAns<\/strong>.(i)The process of evolution of different\u00a0species in a given geographical area starting from a point and literally radiating to other areas or habitat is called adaptive radiation such as alterations in beaks of finches on Galapagos island.
\n(ii) An example where more than one adaptive radiations have occur in an isolated geographical area is Australian Marsupials, where a number of different marsupials evolved from an ancestral stock but within the isolated Australian island, but adapted to different habitats, e.g. Tasmanian wolf (marsupial) and placental wolf (placental mammals).
\nThe above cited example depicts convergent evolution as these marsupials show development of similar adaptive functional structures in unrelated groups of organisms<\/p>\n3 Marks Questions<\/span><\/strong><\/h3>\n
\n <\/strong>
\n (i)Write the names of different gases contained and the conditions set for the reaction in the flask A.<\/strong>
\n (ii)State the type of organic molecule he collected in the water at B. [Delhi 2013C]<\/strong>
\n (iii)Write the conclusion he arrived at. [Foreign 2011]<\/strong>
\nAns<\/strong>.(i)Gases are methane, ammonia,\u00a0hydrogen and water vapour. In ‘A’ flask-electric discharge is created using electrodes.
\n(ii) The organic molecules collected in water at’B’ are amino acids.
\n(iii) He concluded that life could have come from pre-existing non-living organic molecules and their formation was preceded by chemical evolution.<\/p>\n
\n or<\/strong>
\n State the views of Oparin and Haldane on evolution. How does SL Miller’s experiment support their views?\u00a0 [Delhi 2011 c]<\/strong>
\nAns<\/strong>.The theory of biogenesis was proposed by Oparin and Haldane. It states that life could have come from pre-existing non-living organic molecules (e.g. RNA, protein, etc.) and that formation of life was preceded by chemical evolution, i.e. formation of diverse organic molecules from inorganic constituents.
\n
\nIn 1953, Urey and Miller conducted an experiment to prove this theory. They created the conditions of primitive earth-high temperature, volcanic storms, reducing atmosphere containing CH4<\/sub>, NH3<\/sub>, etc. at laboratory scale. They then stimulated electric discharge in a closed flask containing CH4<\/sub>, H2<\/sub>, NH3<\/sub> and water vapour at 800\u00b0C. They observed formation of amino acids. In similar experiments, others observed formation of sugars, nitrogen bases, pigment and fats. These small organic molecules are the building blocks for proteins and other components. Hence, this experiment supported that life has came from pre-existing non-living organic molecules<\/p>\n
\nAns.<\/strong>Divergent evolution is a process where the same structure develops along different directions in different organisms due to adaptations to different needs.\u00a0Divergent evolution leads to homologous structures, as they all have similar anatomical structure and origin, but perform different functions.
\nExamples, the thorn of Bougainvillea and tendrils of Cucurbita are homologous organs as both of them are modified stem which perform different functions.
\nConvergent evolution is a process of evolution, where anatomically dissimilar structures in different organisms perform similar functions.
\nIt leads to analogous structures, in different group of organisms as they perform similar function, but are anatomically different,Example, potato (stem modification) and sweet potato (root modification), flippers of penguins and dolphins<\/p>\n
\n or<\/strong>
\n Australian marsupials and placental mammals are suitable examples of adaptive radiation and convergent evolution. Explain giving reasons. \u00a0[All India 2010 c]<\/strong>
\n or<\/strong>
\n (i)What is adaptive radiation?<\/strong>
\n (ii)Explain with the help of a suitable example, where adaptive radiation has occurred\u00a0to represent convergent evolution. \u00a0[Delhi 2009 c]<\/strong>
\nAns<\/strong>.The process of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitat) is called adaptive radiation. Australian marsupials are a good example.
\nMany Australian marsupials, each different from the other, e.g. kangaroo, sugar glider, etc. evolved from a common ancestral stock, but all within the Australian island continent.
\nWhen more than one adaptive radiation occur in an isolated geographical area, it can be called as convergent\u00a0evolution.
\nAustralian placental mammals also show adaptive radiation in evolving into varieties of such placental mammals, each one of which appear similar to a corresponding marsupial, e.g. placental wolf and Tasmanian wolf, anteater and numbat, etc.<\/p>\n
\n example. \u00a0 [Foreign 2010]<\/strong>
\nAns<\/strong>.Human activities’ i.e. anthropogenic action are found to enhance evolution.
\nFor example,
\n(i) Excessive use of DDT as a fertiliser in crops resulted in evolution of DDT resistant mosquitoes.
\n(ii) Evolution of antibiotic resistant microbes occur due to overuse of antibiotics.<\/p>\n\n
\n (ii)Name and explain the phenomenon that has resulted in the evolution of such diverse species in the region.<\/strong>
\n (iii)Explain giving reasons the existence of placental wolf and Tasmanian wolf sharing\u00a0the same habitat. \u00a0 [Delhi 2009]<\/strong>
\n <\/strong>
\nAns.<\/strong>(i) Australia
\n(ii) The phenomenon responsible for evolution to such diverse species in the region is the adaptive\u00a0radiation. It is evolutionary phenomenon in which different species are evolved in a given geographical area starting from a point and literally radiating to other habitats in that area.
\n(iii) Tasmanian wolf and placental wolf share same habitat since, they exhibit adaptive radiation and evolved into varieties.<\/p>\n
\n (ii) How did Darwin explain the existence of different varieties of finches on Galapagos islands? [All India 2009]<\/strong>
\n or<\/strong>
\n Darwin observed a variety of beaks in small black birds inhabiting Galapagos islands. Explain what conclusion did he draw and how? \u00a0 [All India 2009]<\/strong>
\n <\/strong>
\nAns.<\/strong>(i)Darwin’s finches show variations in beaks due to adaptation to different food habits.
\n(ii) Darwin’s explanation<\/p>\n\n
\n
\n(i)fossils of dinosaurs.<\/strong>
\n(ii) forelimbs of cheetah, bat, whale and human.<\/strong>
\n(iii) thorns of Bougainvillea and tendril of Cucurbita.<\/strong>
\nShows that evolution of life forms has indeed taken place on earth. Explain.[Alt India 2008 C]<\/strong>
\nAns<\/strong>.(i) Fossils of dinosaurs<\/strong> provide palaeontological evidences for evolution. Different aged rock\u00a0sediments contain fossils of different life forms who probably died during the formation of the particular sediment. Some of them appear similar to modern organisms. They represent extinict organisms (e.g. dinosaurs).
\n(ii) Forelimbs of cheetah, bat, whale<\/strong> and human<\/strong> provide evidences from comparative anatomy and morphology. These organisms share similarities in the pattern of bones of forelimbs. Though these forelimbs perform different functions in these animals, they have similar anatomical structure.
\n(iii) Thorns of Bougainvillea<\/strong> and tendril of Cucurbita<\/strong> provide evidences from comparative anatomy and morphology. The thorns of these plants represent homology. They are not anatomically similar structures, though they perform similar functions. Hence, analogous structures are a result of convergent evolution.
\nThese evidences indicate that the evolution of life forms has indeed taken place on earth
\nImportant Questions for Class 12 Biology<\/a>Class 12 Biology<\/a>NCERT Solutions Home Page<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"