SAT Subject Biology Practice Question 203: Answer and Explanation

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Question: 203

13. Which of the following is the smallest unit that can evolve through natural selection?

A. Cell
B. Clade
C. Organism
D. Population
E. Species

Correct Answer: D


Natural selection changes the frequency of alleles within populations. A population is the smallest unit that can be affected by natural selection. An individual organism cannot be changed, within its lifetime, through natural selection.

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