State the Hardy-Weinberg principle.

Allele and genotype frequencies remain constant in a population from generation to generation in the absence of evolutionary influences.

State the Hardy-Weinberg equation for allele frequencies.

p + q = 1, where p is the frequency of the dominant allele and q is the frequency of the recessive allele.

In the equation p + q = 1, what do p and q represent?

p is the frequency of the dominant allele and q is the frequency of the recessive allele.

In the Hardy-Weinberg genotype equation, what does each term represent?

p² is the frequency of homozygous dominant individuals, 2pq is the frequency of heterozygous individuals, and q² is the frequency of homozygous recessive individuals.

When using Hardy-Weinberg equations, how is the frequency of the recessive allele (q) initially determined?

By taking the square root of the homozygous recessive frequency (q²).

OCR A-Level Biology H420

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Patterns of Inheritance

The Hardy-Weinberg principle

2 things to know
Components 02 and 03

Overview

The allele and genotype frequency equations and what each term represents, and the order in which q, then p, then the genotype frequencies are calculated.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Numbers

State and use the Hardy-Weinberg equations.

Key term

Once q has been calculated using Hardy-Weinberg, how is p determined?

Questions from this subtopic

Each one with the model answer underneath.

1
State the Hardy-Weinberg principle.
Model answer
Allele and genotype frequencies remain constant in a population from generation to generation in the absence of evolutionary influences.
2
State the Hardy-Weinberg equation for allele frequencies.
Model answer
p + q = 1, where p is the frequency of the dominant allele and q is the frequency of the recessive allele.
3
In the equation p + q = 1, what do p and q represent?
Model answer
p is the frequency of the dominant allele and q is the frequency of the recessive allele.
4
State the Hardy-Weinberg equation for genotype frequencies.
Model answer
p² + 2pq + q² = 1
5
In the Hardy-Weinberg genotype equation, what does each term represent?
Model answer
p² is the frequency of homozygous dominant individuals, 2pq is the frequency of heterozygous individuals, and q² is the frequency of homozygous recessive individuals.
6
When using Hardy-Weinberg equations, how is the frequency of the recessive allele (q) initially determined?
Model answer
By taking the square root of the homozygous recessive frequency (q²).

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