Evolution
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Explain the salient features of Hugo de Vries theory of mutation. How is Darwin theory of natural selection different from it? Explain.

Hugo de Vries based on his work on evening primrose suggested that variations occurred due to mutations. Hugo de Vries gave the name saltation (single step large mutation) to the mutations that brought about speciation. Darwin aboard the H.M.S Beagle observed that all existing living forms share similarities among themselves and also with other life forms that existed millions of years ago of which many are extinct. The evolution of life forms has been gradual and those life forms better fit in environments that leave more progeny. This is called natural selection and is a mechanism of evolution. Mutations are random and directionless while the variations that Darwin talked about were small and directional.
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    (a) Name the primates that lived about 15 million years ago. List their characteristic features.

    (b) (i) Where was the first man-like animal found?

    (ii) Write the order in which Neanderthals, Homo habilis and Homo erectusappeared on earth.

    State the brain capacity of each one of them.

    (iii) When did modern Homo sapiens appear on this planet?

    Answer

    Which of the following statements is correct

    • Lion and leopard show convergent evolution.

    • Cryptic camouflage is seen in Biston betularia

    • Natural selection is responsible for extinction of dinosaurs.

    • Homo habilis and Homo erectus are closely related.

    Answer

    Analogous structures are a result of

    • convergent evolution

    • shared ancestry

    • stabilising selection

    • stabilising selection

    Answer

    Convergent Evolution' is shown by

    • homologous organs

    • analogous organs

    • vestigial organs

    • all of the above

    Answer
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