SAT Subject Biology Practice Question 288: Answer and Explanation

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Question: 288

18. In chickens, the allele for long tail feathers (T) is dominant over the allele for short tail feathers (t). If a pure-breeding long-tailed chicken (TT) mates with a pure-breeding short-tailed chicken (tt), what percentage of their offspring (if mated with the correct genotype) could give rise to chickens with long tails?

A. 25%
B. 50%
C. 75%
D. 100%
E. unable to determine from the information given

Correct Answer: D

Explanation:

D If a pure-breeding long-tailed chicken (TT) mates with a pure-breeding short-tailed chicken (tt), all of their offspring (the F1 generation) will have the genotype Tt (and have long tails). Thus all of them could produce offspring with long tails.

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