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 ?

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

Answer 1

Answer: (A)

Frequency of dominant allele (say p) $= 0.4$
Frequency of recessive allele (say q)
$= 1 - 0.4 = 0.6$
$\therefore $ 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 $(aa)$
$= q^2 = (0.6)^2 = 0.36$