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Whales, bats, cheetah and human (all mammals) share similarities in the pattern of bones of forelimbs. Though these forelimbs perform different functions in these animals, they have similar anatomical structure- all of them have humerus, radius, ulna, carpals, metacarpals and phalanges in thelr forelimbs.
Such similarities can be interpreted to understand whether common ancestors were shared or not Hence, in these animals, the same structure developed along different directions due to adaptations to different needs. This is divergent evolution and these structures are homologous. Homology indicates common ancestry.
(i) Which of the following information is not appropriate regarding Divergent Evolution ? (a) It forms organs which are similar in appearance b ut have different functions. (b) It shows adaptations for the same function in organisms with different ancestors. (c) It is a change due to different needs in organisms with a common ancestor, which results in structurally distinct organs. (d) It can only b e proven by the study of fossils.(ii) Based on the diagram and text, which statement is incorrectly interprets the relationship between homologous organs and divergent evolution ? (a) Similarity of anatomical structure provides evidence of common ancestor. (b) Variation in functions is due to adaptation to different environmental habitats. (c) Structural similarity suggests the similar habitats and similar needs always lead to similar physical structure (d) Even in animals that appear to be very different such as whales and cheetahs, the pattern of bones is anatomically similar.(iii) What is the key difference between homology and analogy, which is made clear by this case study ? (a) Homology indicates similar function, where analogy indicates common ancestor. (b) Homology indicates similar anatomy but differ in function and common ancestors; where analogy contradicts this. (c) Homology is only seen in aquatic animals, where analogy is seen in terrestrial animals. (d) Homology is the result of convergent evolution.(iv) (Based on figure): In the given figure, comparing the skeletons of 'whale' and 'bat', what adaptation is seen in the bones for swimming and flying ? (a) The humerus is absent in bats, while it is very long in whales. (b) In bats, the phalanges (finger bones) have become extremely long which support the wings, while in whales, they are short and strong which form an oar like structure. (c) In whales, the radius and u lna are fused, while in bats, they are separate. (d) The number of carpals in bats is twice that of whales.

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