Ecology

Ecology covers communities and interdependence, abiotic and biotic factors, adaptations, food chains and trophic levels, the carbon and water cycles, decomposition, biodiversity, and human impacts including pollution, deforestation and global warming.

Start with the vocabulary — population, community, ecosystem, habitat and niche are used precisely in mark schemes and confusing them costs marks. Sampling with quadrats and transects is a required practical and is examined both practically and mathematically, so be comfortable calculating a mean and scaling up to a population estimate. Food chain questions often ask about the consequences of removing one organism, which rewards thinking through the whole web rather than one link. Triple students also cover trophic level efficiency and food security. Human impact questions expect a balanced answer with specific consequences rather than general statements.