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Evolution — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYEvolution3 Marks
Question
State the views of Oparin and Haldane on evolution. How does S.L. Miller's experiment support their views?

OR

  1. Explain the theory of abiogenesis.
  2. How did Miller demonstrate experimentally the chemical evolution that happened three billion years ago?
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Answer

  1. Theory of chemical evolution or abiogenesis was proposed by Oparin and Haldane.
  2. It states that the first form of life could have come from pre-existing non-living organic molecules (like RNA, proteins, etc.) and that formation of life was preceded by chemical evolution, i.e. formation of diverse organic molecules from inorganic constituents.

Miller's experiment:

  1. He created conditions similar to the primitive earth in the laboratory
  2. Electric discharge was produced by using electrodes) in a closed flask, containing methane, hydrogen, ammonia and water vapour.
  3. The temperature was kept at 800°C.
  4. After a week, he observed formation of amino acids.
  5. Such molecules must have reacted among themselves to form giant, self-replicating molecules, the first form of life.

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