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Evolution — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYEvolution4 Marks
Question
  1. Explain taking one example of vertebrates anatomy that evolution of life has occurred on earth.
  2. 'Nature selects for fittest.' Explain with suitable examples.
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Answer

  1. The forelimbs of cheetah, bats and human have a similar anatomical structure. These have bones, humerus, radius, ulna, carpals, metacarpals and phalanges. It indicates divergent evolution, where the same structure has developed along different directions as adaption to different needs. Such structures are called homologous organs and homology indicates common ancestry.
  2. The members of a population vary in characteristics even though they look similar. The population will increase exponentially but the natural resources are limited leading to more competition. The individuals which are fit and adapt themselves are able to survive. They grow reproduce and survive. This is called natural selection by Darwin.

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