AP BIOLOGY

Detailed explanation-1: -1 = p2 + 2pq + q2 P and q each represent the allele frequency of different alleles. The term p2 represents the frequency of the homozygous dominant genotype. The other term, q2, represents the frequency of the homozygous recessive genotype.

Detailed explanation-2: -To determine q, which is the frequency of the recessive allele in the population, simply take the square root of q2 which works out to be 0.632 (i.e. 0.632 x 0.632 = 0.4). So, q = 0.63. Since p + q = 1, then p must be 1-0.63 = 0.37.

Detailed explanation-3: -In the equation, p2 represents the frequency of the homozygous genotype AA, q2 represents the frequency of the homozygous genotype aa, and 2pq represents the frequency of the heterozygous genotype Aa. In addition, the sum of the allele frequencies for all the alleles at the locus must be 1, so p + q = 1.

Detailed explanation-4: -As given, the frequency of a recessive phenotype is 25% (tt). So 25% is the phenotypic ratio of 3:1 of the F2 generation of a monohybrid cross. Therefore, the frequency of the dominant phenotype will be 75%.