If a population is in Hardy-Weinberg equilibrium and the frequency of the recessive allele is 0.3, what percentage of the population is expected to be heterozygous?

• A. 30%
• B. 42%
• C. 72%
• D. 10%

Answer: (B)

To determine the frequency of heterozygous individuals in a population in Hardy-Weinberg equilibrium, we can use the Hardy-Weinberg principle, which provides formulas to calculate the expected genotype frequencies based on allele frequencies.

In this scenario, the frequency of the recessive allele (denoted as q) is given as 0.3. The frequency of the dominant allele (denoted as p) can be calculated using the relationship p + q = 1. Thus, if q = 0.3, then p = 1 - 0.3 = 0.7.

The frequency of heterozygous individuals (represented as 2pq) can be calculated by substituting the values of p and q into the formula:

2pq = 2(0.7)(0.3)

Calculating this:

2pq = 2 * 0.7 * 0.3 = 2 * 0.21 = 0.42

To express this as a percentage, we multiply by 100:

0.42 * 100 = 42%

Therefore, in this population, 42% of the individuals are expected to be heterozygous, which corresponds to the choice indicated. This