A-Level Biology AQA 7402

Species exist as one or more populations.

A population as a group of organisms of the same species occupying a particular space at a particular time that can potentially interbreed.

The concepts of gene pool and allele frequency.

The Hardy–Weinberg principle provides a mathematical model, which predicts that allele frequencies will not change from generation to generation. The conditions under which the principle applies.

The frequency of alleles, genotypes and phenotypes in a population can be calculated using the Hardy–Weinberg equation:

$p^2+2pq + q^2=1$

where $p$ is the frequency of one (usually the dominant) allele and $q$ is the frequency of the other (usually recessive) allele of the gene.