Green algae growing on a sea wall are eaten by grazing snails. Shore crabs eat the grazing snails.
In a scale drawing of the pyramid of biomass, the bar for the shore crabs is 1.6 mm wide.
| Biomass comparison | Relationship |
|---|---|
| Shore crabs and grazing snails | For every 1 g of shore crab biomass, there are 5 g of grazing snail biomass. |
| Grazing snails and green algae | For every 4 g of grazing snail biomass, there are 100 g of green algae biomass. |
How wide should the bar for the green algae be drawn?
8 mm
200 mm
40 mm
0.32 mm
103 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.