Multiple choice

The ultimate source of organic variation is

  1. natural selection

  2. sexual reproduction

  3. hormonal action

  4. mutation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Mutation is the ultimate source of all genetic variation in organisms. Mutations are random changes in DNA that create new alleles. Natural selection acts on existing variation, sexual reproduction reshuffles it, and hormones don't create genetic variation. Without mutation, there would be no new genetic material for evolution to work on.

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