Recall that in Mendel's garden peas, the yellow gene determines flower color, with the A (yellow) allele dominant to the a (green) allele. In a population of 200 plants, the genotype frequencies are 50% AA, 25% Aa, and 25% aa. What are the allele frequencies?
A)50% A, 50% a
B)50% A, 25% a
C)87.5% A, 12.5% a
D)62.5% A, 37.5% a
E)75% A, 25% a

Question

Quizplus · Accepted Answer

Since the total number of alleles in the population is 2*200=400, we can calculate the frequency of the dominant allele (A) by adding up the frequency of AA and half the frequency of Aa (since A is dominant, both AA and Aa individuals will express the yellow phenotype). The frequency of A is therefore (0.5*2 + 0.25*1) / 2 = 0.625 or 62.5%. The frequency of the recessive allele (a) can be calculated by adding up the frequency of aa and half the frequency of Aa (since Aa individuals will only express the yellow phenotype). The frequency of a is therefore (0.25*1 + 0.25*1) / 2 = 0.375 or 37.5%. Therefore, the correct answer is D.

Recall That in Mendel's Garden Peas, the Yellow Gene Determines