Edexcel Biology (B1) Revision Notes

Classification, Variation and Inheritance

Living things are put into groups according to how closely they are related to one another. The Kingdom is the largest group and species the smallest. Each species is given a two-part (binomal) name.
Living things have characteristics that enable them to live in their environment. This is called adaptation .
Members of species show differences called variation, which can be due to genetics or the environment, and which can be continuous or discontinuous.
Darwin's theory of natural selection explains how living things evolved due to variation and survival of the best-adapted.
Alternative forms of genes called alleles are passed from parents to offspring. A dominant allele masks the presence of a recessive allele.
Disorders such as sickle cell disease and cystic fibrosis are inherited. Gentic diagrams help us to analyse who in a family is at risk of having the disorder or being a carrier of the affected allele.