AS and A Level Biology

Outline the theory of evolution as a process leading to the formation of new species from pre-existing species over time, as a result of changes to gene pools from generation to generation

Outline the following examples of selective breeding: • the introduction of disease resistance to varieties of wheat and rice • inbreeding and hybridisation to produce vigorous, uniform varieties of maize • improving the milk yield of dairy cattle

Describe the principles of selective breeding (artificial selection)

Use the Hardy–Weinberg principle to calculate allele and genotype frequencies in populations and state the conditions when this principle can be applied (the two equations for the Hardy–Weinberg principle will be provided, as shown in the Mathematical requirements)

Outline how bacteria become resistant to antibiotics as an example of natural selection

Explain how selection, the founder effect and genetic drift, including the bottleneck effect, may affect allele frequencies in populations

Explain how environmental factors can act as stabilising, disruptive and directional forces of natural selection

Explain that natural selection occurs because populations have the capacity to produce many offspring that compete for resources; in the ‘struggle for existence’, individuals that are best adapted are most likely to survive to reproduce and pass on their alleles to the next generation

Use the t-test to compare the means of two different samples (the formula for the t-test will be provided, as shown in the Mathematical requirements)

Explain the genetic basis of discontinuous variation and continuous variation