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Flashcards · Biology · Variation and Evolution

Evolution and Natural Selection

16 cards

  1. What is evolution?

    A change in the inherited characteristics of a population over time, through natural selection.

  2. How long ago did the first simple life forms develop?

    More than three billion years ago.

  3. What does natural selection act on?

    The variants in a population that give phenotypes best suited to the environment.

  4. What happens to the best-suited individuals?

    They are more likely to survive and breed successfully.

  5. What is passed on to the next generation in natural selection?

    The alleles that gave the advantage.

  6. What is the source of new alleles?

    Mutations.

  7. Does natural selection happen to one individual in its lifetime?

    No. It changes a population over many generations.

  8. What is a selection pressure?

    A factor, such as a predator, that affects survival.

  9. When have two populations formed two new species?

    When they can no longer interbreed to produce fertile offspring.

  10. How can isolation lead to a new species?

    Different environments select different phenotypes, so the populations grow apart.

  11. Why did dark peppered moths become common in industrial areas?

    The trees were blackened by soot, so dark moths were better camouflaged and survived to breed.

  12. Why did pale peppered moths become common again?

    The air was cleaned, the trees became lighter, and pale moths were better camouflaged.

  13. Why is saying "the moth changed colour to hide" wrong?

    Individuals do not change. Mutations are random and the environment selects.

  14. Name two selection pressures.

    Predation and disease (or competition for food).

  15. What must an individual do for its alleles to be passed on?

    Survive and breed.

  16. Three panels of beetles with no labels, showing the green beetles being eaten and the brown ones becoming more common. Describe what is happening in each panel, using the words variation, survive, breed and allele. (Beetles on soil, eaten by birds.)

    Panel 1: there is variation in colour. Panel 2: the green beetles are easier to see, so more are eaten and fewer survive. Panel 3: the brown beetles survive and breed and pass on their alleles, so most of the next generation is brown.