Question

A population of animals found to be in Hardy-Weinberg equilibrium shows that 64% of them possess a dark brown coat. Assume the trait for coat color is inherited through simple dominance, and that dark brown is the dominant trait What is the frequency of the recessive allele in this population?

• A. 0.8
• B. 0.6
• C. 0.2
• D. 0.4
• E. The frequency cannot be determined from the information given.

Answer 1

The correct option is C 0.2

Hardy-Weinberg principle gives the geneticists a tool to determine when evolution is occurring. It uses the binomial expression p² + 2pq + q² to calculate the genotypic and allele frequencies of a population.

where, p² = % homozygous dominant individuals

p = frequency of dominant allele

q² = % homozygous recessive individuals

q = frequency of recessive allele

2pq = % heterozygous individuals

In the given question, dark brown coat is dominant trait. So, % homozygous dominant individuals i.e. p² = 64 % or 0.64

therefore, frequency of dominant allele i.e. p = 0.64^1/2 = 0.8

Since p+ q =1, therefore, frequency of recessive allele q = 1 - p = 1 - 0.8 = 0.2

So, the correct answer is '0.2'.