Question

In humans, Rh-positive individuals have the Rh antigen on their red blood cells, while Rh-negative individuals do not. If the Rh-positive phenotype is produced by a dominant gene (A), and the Rh-negative phenotype is due to its recessive allele (a), what is the frequency of the Rh-positive allele if 84% of a population is Rh-positive?A. 0.04.B. 0.16.C. 0.48.D. 0.60.E. 0.84.

Answer 1

Answer:

D. 0.60

Explanation:

If the population is in Hardy-Weinberg equilibrium, the genotypic frequencies are:

• freq AA = p²
• freq Aa = 2pq
• freq aa = q²

p is the frequency of the Rh positive allele (A) and q is the frequency of the Rh-negative allele (a).

If 84% of the population is Rh-positive, then 16% is Rh-negative and has the genotype aa. Therefore:

q² = 0.16

q = √0.16

q=0.4

And because p+q=1,

p = 1 - 0.4

p = 0.6

The frequency of the Rh-positive allele is 0.6