Food can be preserved by canning. The food is heated to a high temperature and is then closed inside an airtight metal can.
Explain why food that has been canned does not decay.
A few cans become swollen because a gas builds up inside them. Suggest what has happened inside these cans.
40 exam-style questions on AQA GCSE Biology 7.2 Organisation of an ecosystem, covering 7.2.1 Levels of organisation, 7.2.2 How materials are cycled, 7.2.3 Decomposition, and 7.2.4 Impact of environmental change (HT only). Each one has a worked solution and a mark scheme showing where the marks go.