Practice question

Homozygous dominant genotype frequency equals p squared under Hardy-Weinberg equilibrium expectation. Given p squared equals 0.64, p corresponds to square root of genotype frequency, since squaring allele frequency yields genotype proportion. Square root of 0.64 equals 0.8, implying allele A exists at eighty percent frequency in population. Consequently q equals 0.2, giving heterozygotes at 0.32 and recessive homozygotes at 0.04 after expansion. This direct conversion illustrates relationship between observed genotype counts and underlying allele frequencies, essential when dominant phenotype lumps AA and Aa indistinguishably.