Exam Focus

Ecosystems and communities appear regularly on AQA Paper 2, typically in 2-mark definition questions and 4-6 mark extended response questions on interdependence and food webs. Key question patterns include:

• Definition questions (1-2 marks): "State the difference between a population and a community" — use the one-species vs all-species distinction precisely.
• Interdependence questions (4-6 marks): "Explain how removing species X would affect species Y and Z" — always trace the full chain of effects with clear causal language ("because", "therefore", "as a result").
• Abiotic/biotic factor questions (2-3 marks): Identify whether a given factor is abiotic or biotic and explain how it affects a named organism.
• Food web analysis (3-4 marks): Predict population changes from a change to one species — always consider both predators AND prey of the species affected.

Common mark-losing errors: Defining ecosystem as only the living things; forgetting abiotic components; tracing only one direction of effect in interdependence questions; confusing population with community.

Edexcel 1BI0 Paper 2 (T9 — Ecosystems and Material Cycles): Edexcel ecosystems questions typically present a food web diagram or species population data table, then ask you to predict and explain population changes if one species is removed or introduced. "Suggest" questions are common — apply your knowledge of food web interactions to a novel species scenario. Questions on abiotic and biotic factors may include biodiversity data from different habitats, asking you to identify patterns and suggest explanations. Edexcel mark schemes use "Accept…" and "Allow…" for equivalent descriptions of interdependence and energy flow.