Question

A genetics researcher finds that a form of human albinism in a certain population is controlled by the recessive allele, a, for the absence of skin pigment and the completely dominant allele, A, for presence of skin pigment. If the recessive allele occurs in 30% of this population, what percent of the population has skin pigment but also carries the recessive allele?

21 percent
42 percent
91 percent
51 percent

Answer 1

The correct answer will be 42%

Answer 2

Option A

Percent of the population that has skin pigment but also carries the recessive allele is
`21\\` percent

Step-by-step explanation:

As per hardy-weinberg equation,

`p^2+q^2+2pq = 1\\`------------- Eq(A)

where

`p^2= \\`frequency of the homozygous genotype (dominant)

`q^2= \\`frequency of the homozygous genotype (recessive)

`pq= \\`frequency of the heterozygous genotype (recessive)

Also, sum of the allele frequencies at the locus is equal to one.

Thus,
`p + q = 1\\` ------------- Eq(B)

Here frequency of recessive allele i.e
`q = 30\\`%

Substituting this in equation B, we get

`p + 0.3 = 1\\p = 1-0.3\\p= 0.7\\`

frequency of dominant allele i.e
`q = 70\\`%

Substituting the value of frequency of both dominant and recessive allele in equation A, we get

`(0.3^2) + (0.7^2) + 2pq = 1\\pq = (1-0.3^2-0.7^2)/(2) \\pq = (0.42)/(2) \\pq = 0.21\\`

Thus, percent of the population that has skin pigment but also carries the recessive allele is
`21\\` percent