AP BIOLOGY

EVOLUTION

HARDY WEINBERG EQUILIBRIUM

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
T7. What does the variable q represent?
A
Frequency of the heterozygote genotype
B
Frequency of the homozygous recessive genotype
C
The frequency of the recessive allele
D
The frequency of the dominant allele
Explanation: 

Detailed explanation-1: -To determine q, which is the frequency of the recessive allele in the population, simply take the square root of q2 which works out to be 0.632 (i.e. 0.632 x 0.632 = 0.4). So, q = 0.63. Since p + q = 1, then p must be 1-0.63 = 0.37.

Detailed explanation-2: -The Hardy–Weinberg principle relates allele frequencies to genotype frequencies in a randomly mating population. Imagine that you have a population with two alleles (A and B) that segregate at a single locus. The frequency of allele A is denoted by p and the frequency of allele B is denoted by q.

Detailed explanation-3: -In the equation, p2 represents the frequency of the homozygous genotype AA, q2 represents the frequency of the homozygous genotype aa, and 2pq represents the frequency of the heterozygous genotype Aa. In addition, the sum of the allele frequencies for all the alleles at the locus must be 1, so p + q = 1.

Detailed explanation-4: -Hardy-Weinberg Equations The variable ‘p2’ denotes the homozygous dominant genotype (AA), ‘2pq’ denotes the heterozygous genotype (Aa), and ‘q2’ denotes the homozygous recessive genotype (aa). The following conclusions can be inferred through this law: Only sexual reproduction is possible. Mating is a random process.

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