Question 9
The ability to taste PTC is due to a single dominate allele "T". You sampled 215 individuals in biology, and
determined that 150 could detect the bitter taste of PTC and 65 could not. Calculate the frequency of the
heterozygous genotype.
a
50%
b
72%
c
34%
d
17%
The ability to taste PTC is due to a single dominant allele "T". If 150 individuals can detect the bitter taste of PTC, they must be either homozygous dominant (TT) or heterozygous (Tt).
Let's assume that the individuals who cannot taste PTC (65 individuals) are homozygous recessive (tt).
So, for the 215 individuals sampled:
- 150 can taste PTC (TT or Tt)
- 65 cannot taste PTC (tt)
Let's calculate the frequency of the heterozygous genotype (Tt) by using the formula for allele frequency:
Frequency of T allele = (Number of individuals with allele T * 2) / (Total number of alleles in the population)
Number of individuals with allele T = Number of individuals who can taste PTC = 150
Total number of alleles in the population = (150 * 2) + 65 = 365
Frequency of T allele = (150 * 2) / 365 = 300 / 365 = 0.8219
Now, let's calculate the frequency of the heterozygous genotype (Tt) using the Hardy-Weinberg equation:
Frequency of TT = p^2 = (0.8219)^2 = 0.6758
Frequency of tt = q^2 = (1 - 0.8219)^2 = 0.0296
Frequency of Tt = 2pq = 2 * 0.8219 * (1 - 0.8219) = 2 * 0.8219 * 0.1781 = 0.2924
Therefore, the frequency of the heterozygous genotype (Tt) is approximately 29.24%.
The closest option is 34%, so the answer is:
c) 34%