The Hardy-Weinberg principle is written as an equation: p 2 + 2 pq + q 2 = 1. What does the q represent?

frequency of the dominant allele

the size of the population

frequency of the recessive allele

the size of the gene pool

The correct answer is "frequency of the recessive allele".

Explanation:

The Hardy-Weinberg principle, also known as the Hardy-Weinberg equilibrium, establishes that the frequencies of the alleles of certain genes in a population will remain constant over time in the absence of external evolutionary influences. This equilibrium is given by the equation: p2 + 2 pq + q2, where "p" represents the frequency of the dominant allele and "q" represents the frequency of the recessive allele. Under this condition, the sum of p plus q will always be equal to 1.

There is no rigid rule, since the equation is symmetric. p and q could be either the frequency of the dominant allele, or the recessive, as long as we keep track of what's what.

However, general practice usually puts the frequency of the dominant allele as p, and leave q for the frequency of the recessive.