Question

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

• A. 0.16(AA); 0.48(Aa); 0.36(aa)
• B. 0.16(AA); 0.24(Aa); 0.36(aa)
• C. 0.16(AA); 0.36(Aa); 0.48(aa)
• D. 0.36(AA); 0.48(Aa); 0.16(aa)

Answer 1

The correct option is A 0.16(AA); 0.48(Aa); 0.36(aa)

Recall the the Hardy-Weinberg equation - ${}^{}$ p^2+2\mathrm{pq}+q^2=1${}^{}$

Given in the above question :-

Frequency of dominant allele (say p) = 0.4;

Frequency of recessive allele (say q)

Following the formula: p +q = 1

Therefore, q = 1 - 0.4 = 0.6

Frequency of homozygous dominant individuals (AA)

$p^2={(0.4)}^2=0.16$

Frequency of heterozygous individuals (Aa)

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

Frequency of homozygous recessive individuals (aa)

$q^2={(0.6)}^2=0.36$