SAT Subject Biology Practice Question 114: Answer and Explanation

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Question: 114

4. Crabs and lobsters are both members of the suborder Pleocyemata. Both possess a tail; however, in the crab, this structure is very small and not used. This structure can be considered an example of all of the following EXCEPT

A. convergent evolution
B. vestigial structure
C. divergent evolution
D. genetic fitness
E. homologous structure

Correct Answer: A


Convergent evolution occurs when two unrelated species over time adapt the same structure. This is the reverse of what has occurred with tails in lobsters and crabs. An unused evolutionary relic can be termed a vestigial structure and also a homologous structure. This is an example of divergent evolution, where close relatives have begun to adapt differently from one another.

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