Question

In a population at Hardy Weinberg equilibrium, the allele frequency of ‘A’ is 0.3, the expected frequency of ‘Aa’ individuals is
A. 0.21
B. 0.42
C. 0.63
D. 0.18

Answer 1

Hint: A mathematical equation was given by Hardy Weinberg. It is a type of equation that can be used to calculate the genetic variation of a certain population at equilibrium. If allele frequencies are known then, the frequency of three genotypes can be calculated.

Complete answer: The Hardy Weinberg equation can be used to estimate the occurrences of alleles in a population.
The equation is as follows-
$p^2+2pq+q^2=1$
In the above equation, where p is the frequency of the dominant allele and q represents the frequency of the recessive allele. According to the information provided in the question, p is represented by A, and q is represented by a. The three expressions indicate the frequencies of three genotypes-
$P^2=$frequency of the homozygous dominant genotype AA
$2Pq=$frequency of heterozygous genotype Aa
$$q^2=$$frequency of homozygous recessive genotype aa
Thus,
$\left(p+q\right)=1$
$\left(0.3+q\right)=1$
$$q=1-03=0.7$$
$Aa=2\times 0.3\times 0.7=0.42$
Hence, the correct option is (B), i.e., 0.42

Note: Allele frequency is the number of occurrences of an allele in a population. It can be determined by using the Hardy Weinberg equation. It states that the genetic variation in a population remains constant from one generation to the next in the absence of some disturbing factors. It is a type of null model between genotypic frequencies and alleles. The population should not experience any mutation, random mating, etc.