Question

With the help of an algebraic equation, how did Hardy-Weinberg explain that in a given population the frequency of occurrence of alleles of a gene is supposed to remain the same through generations? [2]

Answer 1

According to Hardy–Weinberg principle the allele and genotype frequencies in a population will remain constant from generation to generation in the absence of other evolutionary influences [1]

In a population of diploid organisms. [0.5]
If frequency of allele A = p
And frequency of allele a = q, then the expected genotype frequency under random mating are -
$AA=P^2$ (for AA homozygotes)
$aa=q^2$ (for aa homozygotes)
Aa =2pq (for Aa heterozygotes)

In the absence of selection, mutation, genetic drift or other forces, p and q are constatnt through generations.

Therefore, $p^2+2pq+q^2=1$ [0.5]