Practice MCAT Question - Q157 - Answer!
If a polygenic trait in plants involves genes at three different loci, which determine fruit weight, and each dominant allele contributes 0.5 lb, while each recessive allele contributes .25 lb, what would fruits weigh in individuals that are heterozygous at all three loci?
A. 2 lb
B. 2.25 lb
C. 2.5 lb
D. 2.75 lb
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The correct answer is (B). If the plant was heterozygous at all three loci (AaBbCc), and each dominant allele contributes 0.5 lb while each recessive allele contributes 0.25 lb, the fruit would weigh 2.25 lb.