A food chain in a reed bed is:
reeds → water snails → perch → herons
The table shows the biomass at the first three trophic levels.
| Organism | Biomass in kg |
|---|---|
| Reeds | 1200 |
| Water snails | 180 |
| Perch | 30 |
A student draws a pyramid of biomass in which the bar for the reeds is 20.0 cm wide.
The efficiency of biomass transfer from perch to herons is the same as the efficiency of biomass transfer from reeds to water snails.
Calculate the width of the bar for the herons.
Give your answer in 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.