EvolutionNEET Zoology · Class 12 · NCERT Chapter 3

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Forelimbs of cats, lizards, whales, and bats, despite their different functions, share a common ancestral structure, making them homologous organs. NCERT XII chapter Evolution discusses homologous organs as structures with a common evolutionary origin but different functions, so option (c) is correct.

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Wings of bats and wings of pigeons are analogous structures, as they serve a similar function (flight) but have different evolutionary origins. NCERT XII chapter Evolution defines analogous structures as those with similar functions but different evolutionary backgrounds, so option (a) is correct.

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Industrial melanism is an example of natural selection.

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Analogous structures are a result of convergent evolution.

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Artificial selection to obtain cow yielding higher milk output will shift the peak to one direction, hence, will be an example of Directional selection. In stabilizing selection, the organisms with the mean value of the trait are selected. In disruptive selection, both extremes get selected.

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Hugo de Vries proposed that evolution occurs through saltation, which refers to large, sudden mutations that result in new species. NCERT XII chapter Evolution discusses de Vries' mutation theory, emphasizing saltation as a key mechanism, so option (b) is correct.

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Divergent evolution leads to different structures in different organisms, but the eye of octopus, bat, and man are examples of convergent evolution, where similar structures evolve independently. NCERT XII chapter Evolution discusses these examples, so option (d) is incorrect.

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The similarity of bone structure in the forelimbs of many vertebrates is an example of homology, indicating a common ancestry. NCERT XII chapter Evolution defines homologous structures as those with a common evolutionary origin, so option (c) is correct.

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Ref. XII NCERT Chapter- 05, Page No. 76 Law of Segregation is universally followed.

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Flippers of penguins and dolphins are examples of convergent evolution, where unrelated organisms develop similar traits due to similar environmental pressures. NCERT XII chapter Evolution discusses this concept, so option (b) is correct.

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Darwin’s Finches evolved due to natural selection in response to environmental changes, and drug-resistant eukaryotes have evolved due to the use of drugs, both examples of anthropogenic influence. Man-created breeds of domesticated animals and herbicide-resistant weeds are also influenced by human activity, but the question specifically asks for organisms that have evolved due to changes in the environment, making option (b) the most accurate.

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S.L. Miller's experiment used a mixture of ${\text{CH}}_4$, ${\text{H}}_2$, ${\text{NH}}_3$, and water vapor at a high temperature (800°C) to simulate early Earth conditions and produce amino acids. This setup is described in NCERT XII chapter Evolution, so option (a) is correct.

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Karl Ernst von Baer criticized the idea that embryos of different species pass through the same stages of development, which was a key argument for embryological support of evolution. NCERT XII chapter Evolution discusses von Baer's critique of recapitulation theory, so option (a) is correct.

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- Adaptive radiation: Darwin's finches (iv)
- Convergent evolution: Wings of butterfly and bird (iii)
- Divergent evolution: Bones of forelimbs in Man and Whale (ii)
- Evolution by anthropogenic action: Selection of resistant varieties due to excessive use of herbicides and pesticides (i)

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Option (2) is correct because in directional natural selection more individuals acquire value other than the mean character value. Option ( 3) is incorrect because in disruptive change, more individuals acquire peripheral character value at both ends of the distribution curve. Option (4) is incorrect because there is no random change in natural selection. Option (1) is incorrect because natural selection leads to stabilisation when more individuals acquire mean character value.

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Option (4) is the correct answer bec ause flippers of penguins and dolphins are analogous organs as they help in swimming but do not have the same structure. Option (3), (1) and (2) are true statements and hence cannot be the correct answer. Homologous organs have the same structure but have different functions according to the needs of the organisms. Hence, homology indicates common ancestry. Analogous structures have developed for the same function but do not show a similarity in structure. Hence, they are a result of convergent evolution. Sweet potato is a root modification for food storage whereas potato is an underground stem modification for storage. Hence they are analogous.

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RNA mutates at a higher rate due to its less stable structure and lack of proofreading mechanisms, making Statement I true. Viruses with RNA genomes and shorter life spans, such as HIV, indeed mutate and evolve faster, making Statement II true. Both statements are supported by NCERT XII chapter Evolution, so option (b) is correct.

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Correct answer is option (4) because the correct sequence of stages of human evolution from past to recent is Homo habilis → Homo erectus → Homo neanderthalensis → Homo sapiens

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The correct answer is option (3), because the flippers of the Penguins and Dolphins perform similar function but they are not anatomically similar structures. This is example of analogous structures.

- Option (1) is incorrect as adaptive radiation is the process of evolution of different species in a given geographical area starting from a point and literally radiating to the other areas of geography.

- Option (2) is incorrect as natural selection is a key mechanism of evolution.

- Option (4) is incorrect as divergent evolution results in the formation of homologous structures.

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The correct answer is option no. (4) (A) Mesozoic Era – (III) Birds & Reptiles (B) Proterozoic Era – (I) Lower invertebrates (C) Cenozoic Era – (IV) Mammals (D) Paleozoic Era – (II) Fish & Amphibia

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As in the F₁ generation the carrier female and non-affected (normal, not carrier) had affected male child that means the genetic disorder is sex-linked recessive.

The consanguineous mating between female (X^cX) and male (X^cY)

Out of 4 child only one is carrier i.e. $\frac{1}{4}$.