A scientist grows two groups of duckweed plants in transparent cabinets. The light intensity, temperature, water supply and mineral ion supply are the same in both cabinets. The carbon dioxide concentration differs.
After the same growth period, the scientist measures the mean biomass of the plants.
| Carbon dioxide concentration (%) | Mean biomass at the start (g) | Mean biomass at the end (g) |
|---|---|---|
| 0.04 | 2.40 | 2.70 |
| 0.10 | 2.40 | 3.15 |
Calculate how many times as large the increase in mean biomass was at 0.10% carbon dioxide compared with the increase at 0.04% carbon dioxide.
Explain how the difference in carbon dioxide concentration could account for the difference in biomass gain.
87 exam-style questions on Edexcel GCSE Biology 6.1 Photosynthesis, covering 6.1.1 Photosynthetic organisms as producers, 6.1.2a Limiting factors on the rate of photosynthesis, 6.1.2b Interactions of limiting factors on photosynthesis, and 6.1.3 Inverse square law and light intensity. Each one has a worked solution and a mark scheme showing where the marks go.