Question

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait ( aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

Answer 1

Answer:

Option C

Explanation:

Complete question

A large population of laboratory animals has been allowed to breed randomly for a number of generations. After several generations, 25% of the animals display a recessive trait ( aa), the same percentage as at the beginning of the breeding program. The rest of the animals show the dominant phenotype, with heterozygotes indistinguishable from the homozygous dominants.

What is the estimated frequency of allele A in the gene pool?

Select one:

a. 0.05

b. 0.25

c. 0.50

d. 0.75

e. 1.00

Solution

Given

heterozygotes  are indistinguishable from the homozygous dominants

This means that the phenotype of offspring with genotype Aa and AA would be the same

We know that frequency of recessive individual in the total population is equal to $0.25$

Considering the population is in HW equilibrium-

$q^2 = 0.25\\q = 0.5$

As per the first equilibrium equation of HW, we know that

$p + q = 1\\0.5 + p = 1\\p = 1-0.5\\p = 0.5$

Here p represents the frequency of A allele in the population

Hence, option C is correct