Scientists grew identical crop plants for the same length of time. Each group received the same amount of light energy and the same range of wavelengths.
| Treatment | Temperature in °C | Carbon dioxide concentration in ppm | Percentage of light energy transferred into new biomass |
|---|---|---|---|
| A | 10 | 400 | 0.5 |
| B | 10 | 800 | 0.5 |
| C | 25 | 400 | 0.9 |
| D | 25 | 800 | 1.4 |
The crop plants are part of this food chain:
crop plant → leaf beetle → insect-eating bird
Using the data, suggest why increasing the carbon dioxide concentration had different effects at 10 °C and 25 °C.
Scientists apply a transparent coating to another group of plants. The coating reduces the proportion of light reflected from the leaf surface. Temperature and carbon dioxide concentration do not limit photosynthesis in these plants.
Suggest how the coating would affect the percentage of light energy transferred into new biomass. Explain your answer.
The scientists predict that using the conditions in treatment D instead of treatment C would increase the biomass of the birds. Explain why the increase in the mass of bird biomass would be much smaller than the increase in the mass of plant biomass.
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.