The idea of use and disuse of organs for evolution of organism was proposed by
The idea of use and disuse of organs for evolution of organism was proposed by
Options
Correct option: D — Lamarck
Jean-Baptiste Lamarck proposed that evolution occurs by the use and disuse of organs and the inheritance of acquired characters.
- His famous example: giraffes evolved long necks by continuously stretching to reach high foliage, and this acquired trait was passed on.
Marking Scheme
- 11 mark: correct option D (Lamarck).
- 2No marks for Darwin, who gave natural selection, not use and disuse.
Hint
'Use and disuse' + inheritance of acquired characters = one scientist's name.
Quick Oral Answer
The idea of use and disuse of organs and inheritance of acquired characters was given by Lamarck, so the answer is D.
Analysis & Explanation
Concept
Lamarckism (early 19th century) held that (i) organs used more become better developed while unused ones degenerate, and (ii) such acquired characters are inherited by offspring.
Why D is correct
'Use and disuse of organs' is the signature phrase of Lamarck's theory of evolution.
Why the distractors are wrong
- A — Charles Darwin: proposed natural selection / survival of the fittest, not use and disuse.
- B — Thomas Malthus: an economist whose essay on population growth influenced Darwin, but he gave no theory of organic evolution.
- C — Hugo de Vries: proposed the mutation theory (evolution by sudden large 'saltations'), based on his work on Oenothera (evening primrose).
Exam trap
Lamarck's mechanism was later disproved — acquired somatic characters are not inherited (Weismann's germplasm theory) — but the proposer is still Lamarck.
Common Mistakes
- 1Selecting Darwin — Darwin's mechanism was natural selection, not use and disuse.
- 2Confusing Hugo de Vries (mutation theory) with Lamarck's acquired-characters idea.
Interesting Facts
Lamarck published his theory in 'Philosophie Zoologique' in 1809, the same year Charles Darwin was born.
August Weismann's experiment of cutting off mice tails for many generations — with offspring still born with tails — is the classic disproof of Lamarck's inheritance of acquired characters.
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Frequently Asked Questions
What is Lamarck's theory of evolution?
Lamarckism states that organs used frequently become stronger and better developed while unused organs degenerate, and that these characters acquired during an organism's lifetime are inherited by its offspring, driving evolution — illustrated by the long neck of the giraffe.
Why is Lamarck's theory rejected today?
Acquired somatic (body) characters are not passed to offspring because they do not alter the DNA of germ cells. Weismann's germplasm theory and his mouse-tail experiment demonstrated that only changes in the reproductive cells are heritable.