The table shows population sizes during part of a predator–prey cycle.
| Month | Number of prey | Number of predators |
|---|---|---|
| 1 | 40 | 8 |
| 2 | 80 | 12 |
| 3 | 120 | 20 |
| 4 | 75 | 32 |
| 5 | 35 | 24 |
| 6 | 45 | 10 |
Which explanation best accounts for the changes from month 3 to month 4?
Predators increase as prey decline because reduced food availability increases the reproductive rate of predators.
Prey decline as predators increase because predators compete with the prey for the same food source.
Predators increase after earlier plentiful food improves reproduction, while greater predation contributes to the prey decline.
Prey decline before predators increase because fewer prey allow each predator to obtain more food overall.
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.