A gene exists as two alleles in a population of freely mating individuals. If 40% of the population carries the recessive allele (a) for the gene, what percentage of the population has the homozygous recessive aa genotype?

Question

Quizplus · Accepted Answer

Assuming Hardy-Weinberg equilibrium, we can use the equation p + q = 1, where p is the frequency of the dominant allele and q is the frequency of the recessive allele. Since we know that 40% of the population carries the recessive allele, q = 0.4. Therefore, p = 0.6. 
To find the frequency of the homozygous recessive genotype (aa), we can use the equation q^2 = 0.4^2 = 0.16 or 16%.

A Gene Exists as Two Alleles in a Population of Freely