Inheritance, variation and evolution

Inheritance, variation and evolution is a cornerstone of GCSE Biology, exploring how traits are passed from parents to offspring and how species change over time. You'll start with DNA, genes, and chromosomes, learning how genetic information is stored and replicated. This leads into understanding how alleles determine characteristics, from dominant and recessive traits to codominance and sex-linked disorders. The topic also covers variation — both genetic and environmental — and how it provides the raw material for natural selection. Finally, you'll study evidence for evolution, including fossils, antibiotic resistance in bacteria, and the work of Darwin and Wallace.

This topic is crucial because it explains the diversity of life on Earth and has real-world applications in medicine, agriculture, and conservation. For example, understanding inheritance helps predict the risk of genetic disorders like cystic fibrosis, while knowledge of evolution guides the development of new antibiotics and vaccines. In the AQA GCSE exam, this topic appears in both Paper 2 and as part of the 'Synoptic' questions that link different areas of biology. Mastering it will also help you understand topics like classification, biodiversity, and genetic engineering.

You'll need to recall specific terminology (e.g., homozygous, heterozygous, genotype, phenotype) and apply it to genetic crosses using Punnett squares. You'll also need to evaluate evidence for evolution and explain how natural selection leads to adaptation. The topic builds on earlier work on cells and reproduction, so make sure you're confident with mitosis, meiosis, and the structure of DNA before diving in.