Question

800 people dwell on an island, 16 are homozygous recessive for a trait that has only two different types of alleles in the population. Based on this information, find the number of heterozygotes in the population?

• A. 96
• B. 32
• C. 128
• D. 192

Answer 1

The correct option is D 192

Since 16 individuals are homozygous recessive for the trait
Frequency of homozygous recessive (aa)= $\frac{16}{800}$= 0.02
So $q^2$ = 0.02
Therefore, q = $\sqrt{q^2}$= $\sqrt{0.02}$
q = 0.14

We know that p + q = 1
p + 0.14 = 1
p = 1 - 0.14
p = 0.86


Frequency of heterozygous individual = 2pq
2pq = $2\times 0.86\times 0.14$
2pq = 0.24


To calculate the number of heterozygous individuals
Number of heterozygous individuals = (frequency of heterozygous individuals) X (total number of individuals)

Number of heterozygous individuals = $0.24\times 800$
Number of heterozygous individuals = 192