SAT Subject Biology Practice Question 117: Answer and Explanation

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Question: 117

7. An ecosystem undergoes a sudden drastic change that now favors organisms with an extreme phenotype. This is an example of

A. genetic drift
B. founder effect
C. artificial selection
D. disruptive selection
E. directional selection

Correct Answer: E


Selection for an extreme phenotype would shift the mean for the population in the direction of that extreme. This is known as directional selection. It is not disruptive selection because only one extreme is selected for.

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