​Consider alleles ‘A’ and ‘a’ in a population. The frequency of heterozygotes will be highest when:​

Correct option is C

Explanation:

The frequency of heterozygotes (Aa) in a population can be determined using the Hardy-Weinberg equilibrium equation:

P²  + q² + 2pq = 1

where:

• p = frequency of allele A
• q = frequency of allele a
• p²= frequency of AA (homozygous dominant)
• q² = frequency of aa (homozygous recessive)
• 2pq = frequency of Aa (heterozygotes)

The frequency of heterozygotes (2pq) is maximized when p = q = 0.5 because:

$$2pq=2(0.5\times 0.5)=0.5$$

When A and a are equally frequent (p = q = 0.5), the product pq is maximized, leading to the highest heterozygote proportion.

Information Booster

1. Hardy-Weinberg Principle: Describes how allele frequencies remain constant in an ideal population without evolutionary influences.
2. Maximum Heterozygosity: The heterozygote frequency (2pq) is highest when both alleles A and a have equal frequencies (p = q = 0.5).
3. Effect of Unequal Allele Frequencies: If p > q or q > p, heterozygote frequency decreases.
4. Homozygote Frequency: As one allele becomes more frequent, homozygote frequency increases, and heterozygote frequency decreases.
5. Applications in Population Genetics: Understanding heterozygosity is crucial in evolutionary studies, genetic diversity assessment, and conservation biology.
6. Deviations from Hardy-Weinberg Equilibrium: Mutation, selection, genetic drift, migration, and non-random mating can alter allele frequencies.

Additional Information

• Option (1) Frequency of ‘A’ is more than frequency of ‘a’ (Incorrect)

  • If p > q, pq is lower than when p = q, reducing heterozygotes.

• Option (2) Frequency of ‘A’ is less than frequency of ‘a’ (Incorrect)

  • If p < q, pq is still lower than its maximum possible value.

• Option (4) Frequency of ‘A’ and ‘a’ affects the frequency of homozygotes, not heterozygotes (Incorrect)

  • This statement is misleading because allele frequencies affect both heterozygotes and homozygotes.