Question

The presence of freckles is due to a dominant allele. Four percent of the individuals in a particular population lack freckles. Use the Hardy-Weinberg formula to calculate the percentage of individuals in this population who are homozygous dominant for freckles.

a) 32%
b) 80%
c) 64%
d) 20%
e) 4%

Answer 1

Using the Hardy-Weinberg principle, the frequency of individuals in the population who are homozygous dominant for freckles is calculated as 64%, making (c) the correct answer.

Step-by-step explanation:

The presence of freckles is due to a dominant allele, and we're told that 4 percent of the individuals in a particular population lack freckles, which means they are homozygous recessive (aa). In Hardy-Weinberg equilibrium, the frequencies of alleles must add up to 1 (p + q = 1), where p is the frequency of the dominant allele and q is the frequency of the recessive allele. The frequency of the recessive genotype (q²) is given as 0.04, so q equals the square root of 0.04, which is 0.2. Therefore, p would be 1 - q, which is 1 - 0.2, equaling 0.8. To find the frequency of individuals that are homozygous dominant (AA), we calculate p² which is 0.8². This equals 0.64, or 64%.

The percentage of individuals in this population who are homozygous dominant for freckles is therefore 64%, making (c) the correct answer.

Answer 2

Option C

Step-by-step explanation:

Allele for dominant freckle trait is "F"

Allele for recessive no freckle trait is "f"

Given -

Population lacking freckles
`= 4`%

As per Hardy Weinberg's equilibrium equation

p represents the frequency of dominant allele in a given population and
`p^2` represents the frequency of dominant individuals in a given population

Like wise

q represents the frequency of recessive allele in a given population and
`q^2` represents the frequency of recessive individuals in a given population

`q^2 = 0.04\\q = 0.2`

Frequency of dominant allele
`= 1- 0.2\\= 0.8`

Frequency of homozygous recessive individual

`q^2 = 0.4`

Frequency of homozygous dominant individual

`q^2 = 0.4`
`0.8^2\\= 0.64`

Option C is correct