Question

In chickens, a flat single comb is a recessive trait, while the short, thick rose comb is dominant. In a particular population of chickens, 45 are homozygous for the dominant trait, 30 are heterozygous dominant, and 25 have the recessive trait. Which expression is the correct way to calculate the frequency of the recessive allele?

Answer 1

Answer:

The correct answer would be 0.5

The same can be explained with the help of Hardy-Weinberg equation

p² + q² + 2pq = 1

p + q = 1 Where,

• p refers to the frequency of a dominant allele in a population.
• q refers to the frequency of a recessive allele in a population.
• P² refers to the frequency of homozygous dominant trait.
• q² refers to the frequency of homozgous recessive trait.
• 2pq refers to the frequency of heterozygous dominant trait.

Total number of individuals = 45 + 30+ 25 = 100

So, the frequency of recessive trait = 25/100 =0.25.

Thus, the value of q² = 0.25

So, q would be equal to square root of 0.25 which comes out to be 0.5

Answer 2

The Hardy-Weinberg equation is as follows:p² + 2pq + q² = 1

Where p is the frequency of the homozygous dominant genotype, q is the frequency of the homozygous recessive genotype and 2pq is the frequency of the heterozygous genotype. Using the 2pq term here,

Frequency of heterozygous = 2 * 0.7 * 0.3

There fore, the answer is 2 x (0.70) x (0.30)