Question

A gene locus has two alleles A, a. If the frequency of dominant allele A is 0.4, then what will be the frequency of homozygous dominant, heterozygous and homozygous recessive individuals in the population?

(1) 0.36(AA); 0.48(Aa); 0.16(aa)

(2) 0.16(AA); 0.24(Aa); 0.36(aa)

(3) 0.16(AA); 0.48(Aa); 0.36(aa)

(4) 0.16(AA); 0.36(Aa); 0.48(aa)

Answer 1

Correct option: (3) 0.16(AA); 0.48(Aa); 0.36(aa)

Explanation:

Frequency of dominant allele (say p) = 0.4

Frequency of recessive allele (say q)

= 1 – 0.4 = 0.6

∴ Frequency of homozygous dominant individuals (AA)

= p2 = (0.4)2 = 0.16

Frequency of heterozygous individuals (Aa)

= 2pq = 2(0.4)(0.6) = 0.48

Frequency of homozygous recessive individuals (aa)

= q2 = (0.6)2 = 0.36