SAT Subject Biology Practice Question 415: Answer and Explanation

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Question: 415

5. A self-pollinating plant with orange flowers and alternating leaf arrangement produces 47 plants with red flowers and alternating leaves, 103 plants with orange flowers and alternating leaves, and 51 plants with yellow flowers and alternating leaves.

If a yellow-flowered offspring were self-pollinated, what would the resulting plants' flowers look like?

A. 100% yellow
B. 100% red
C. 100% orange
D. 50% yellow, 50% red
E. 75% red, 25% yellow

Correct Answer: A

Explanation:

A The only way plants can have yellow flowers is if they are homozygous for yellow allele. If a plant is homozygous for a particular trait and is self-pollinated, it can only produce plants with that trait.

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