# Hardy Weinberg HELP ASAP?

3) A dominate allele, T, codes for the ability to taste the compound phenylthiocarbamide (PTC ). People who are homozygous for the recessive allele,t, are un able to taste PTC. In a Genetics class of 125 students, 88 students can taste PTC and 37 cannot.

A) calculate the expected frequencies for the T and t alleles in the student population.

B) How many students would you expect to be heterozygous for the tasting gene?

C) How many students would you expect to be homozygous dominant for the tasting gene?

D) How could you check your answers for parts (b) and (c)

### 2 Answers

- Anonymous8 years agoFavorite Answer
Hardy-Weinberg equilibrium equation:

p² + 2pq + q² = 1 (or TT + Tt + tt = 1)

p + q = 1 (T + t = 1)

In this problem: q² = tt =37/125 = 0.296

A) expected frequency for the t allele = q = √q² = √0.296 = 0.544

expected frequency for the T allele = p = 1 - q = 1 - 0.544 = 0.456

B) expected frequency for heterozygous genotype (Tt) = 2pq = 2*0.456*0.544=0.496

expected number of heterozygous students = 0.496 * 125 = 62 students

C) expected frequency for homozygous dominant genotype (TT) = p² = .456² = 0.208

expected number of homozygous dominant students = 0.208*125 = 26 students

D) You could check your answer for part b and c by mating the students who can taste PTC with the students who cannot to observe the phenotypes of the offspring. However, I personally think this is impossible.