In peas, a gene controls flower color such that R = purple and r = white. In an isolated pea patch, there are 36 purple-flowering plants and 64 white-flowering plants. Assuming Hardy-Weinberg equilibrium, what is the value of q for this population?

a. 0.36.

b. 0.64.

c. 0.75.

d. 0.80.

D

Explanation:

R = Purple,

r = white

Let q for recessive allele and p for dominant allele

p+q=1

Frequency of q² = 64/100 = 0.64

So the frequency of the recessive genotype is 0.64, that is, the frequency of qq (q²) is 0.64.

So by Hardy-Weinberg equilibrium

Therefore, the frequency of the recessive allele, usually called q, is √0.64 = 0.80