Answer: c - The proportion of the population that is heterozygous (Aa) for this trait is 0.50
Explanation: Percentage of those with homozygous recessive alleles (aa) in the population has been given as 25%. We can represent this as q².
Recall that Hardy-Weinberg provides the equation p² + 2pq + q² = 1, where
P² = homozygous dominant alleles
q² = homozygous recessive alleles
2pq = heterozygous alleles
q² = 25% = 25/100 = 0.25
q = √0.25 = 0.5
Also recall that for two alleles, p and q, p + q = 1.
Therefore, p = 1 - q = 1 - 0.5 0.5
Since we now have the values of p and q, we can calculate the proportion of heterozygous alleles (Aa) as 2pq = 2 x 0.5 x 0.5 = 0.5
