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3 marksBiological Evolution

CSEC Biology · May/June 2021 · Paper 2 · Question 6(d)(i)

A species of toxic toad was introduced to an island inhabited by iguanas that ate mainly toads. Many iguanas died, but some survived. Several years later, biologists observed that the adult iguanas' tail length had increased by 10 percent.

Suggest three possible reasons for the increase in tail length observed in these iguanas.

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Other parts of this question

  1. 6(a)Outline Darwin's theory of natural selection.[2 marks]
  2. 6(b)Explain why the development of antibiotic resistance by bacteria is considered to be an example of natural selection.[2 marks]
  3. 6(c)A farmer wishes to use artificial selection to alter the characteristics of his crops. Suggest two ways in which artificial selection will benefit the farmer.[2 marks]
  4. 6(d)(ii)Provide an explanation to support the conclusion that the iguanas with longer tails were not a new species.[2 marks]
  5. 6(e)Describe two situations which may lead to the evolution of a new species.[4 marks]

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