A food chain in a pond is shown.
algae → \rightarrow\,→ water flea → \rightarrow\,→ stickleback → \rightarrow\,→ heron
Which organism is the secondary consumer, and at which trophic level is it?
Water flea, at trophic level 3
Stickleback, at trophic level 2
Heron, at trophic level 3
Stickleback, at trophic level 3
61 exam-style questions on AQA GCSE Biology 7.4 Trophic levels in an ecosystem, covering 7.4.1 Trophic levels, 7.4.2 Pyramids of biomass, and 7.4.3 Transfer of biomass. Each one has a worked solution and a mark scheme showing where the marks go.