Pike are fish that eat smaller fish called perch.
The number of pike in a lake increases.
What is most likely to happen next?
Perch numbers rise, then pike numbers rise because there is more food.
Perch numbers fall, then pike numbers fall because there is less food.
Perch numbers fall, then pike numbers rise because there is more space.
Perch numbers rise, then pike numbers fall because of more competition.
111 exam-style questions on OCR GCSE Biology 4.1 Ecosystems, covering 4.1.1 Cycling of materials in ecosystems, 4.1.2 Microorganisms in cycling materials, 4.1.3 The carbon and water cycles, 4.1.4 Factors affecting decomposition, 4.1.5 Levels of organisation in an ecosystem, 4.1.6 Abiotic and biotic factors affecting communities, 4.1.7 Interdependence and competition, 4.1.8 Trophic levels, 4.1.9 Pyramids of biomass, and 4.1.10 Efficiency of biomass transfers. Each one has a worked solution and a mark scheme showing where the marks go.