Question

If you examine a population for a particular gene where b represents the dominant allele and b represents the recessive allele, you find that the allele frequencies for this gene are p = 0.3 and q = 0.7. if this population is not evolving, what would be the frequency of the heterozygous genotype?

a. 0.09
b. 0.21
c. 0.30
d. 0.42
e. 0.49

Answer 1

Assuming Hardy-Weinberg equilibrium

B=dominant, P(B)=0.3
b=recessive, P(b)=0.7

Genotypes are given by:

(P(B)+P(b))^2=(0.3+0.7)^2=0.3^2+2*0.3*0.7+0.7^2=0.09+0.42+0.49=1

P(BB)+P(Bb)+P(bb)=1

Which means

P(BB)=0.09 (homozygous dominant genotype)

P(Bb)=0.42 (heterozygous genotype)

P(bb)=0.49 (homozygous recessive genotype)