The compound phenylthiocarbamide (PTC) tastes very bitter to most persons. The inability to taste PTC is controlled by a single recessive allele. In the American white population, about 70% can taste PTC while 30% cannot (are non-tasters). Estimate the frequency of the Taster (T) and non-taster (t) alleles in this population, as well as the frequencies of the diploid genotypes.

p = 0.7, q = 0.3 and p² = 0.49  2pq = 0.42 and q²= 0.09

Explanation:

The alleleic frequency of T = p is 70% which is 70/100= 0.7

The alleleic frequency of t= q is 30% which is 30/100= 0.3.

check: p+q = 1= 0.7 + 0.3 = 1.

The tasters could exist in genotypes as TT (p) or as heterozygous Tt (2pq) while the none tasters exist generally as tt (q).

thus the genotypic frequency of TT (p²) = 0.7² = 0.49

the genotypic frequency of Tt (2pq) = 2 x 0.7 x 0.3 = 0.42

the genotypic frequency of tt (q²) = 0.32 = 0.09

check: p²+ 2pq + q² = 1