A commercial hydroponics facility is investigating methods to optimize the yield of spinach (Spinacia oleracea). They are researching how different concentrations of nitrogen in the nutrient solution affect both the rate of photosynthesis and the final dry biomass of the crop.
The table below shows the results of their investigation:
| Nitrogen concentration (mg L−1^{-1}−1) | Rate of photosynthesis (arbitrary units) | Dry biomass produced (g/plant) |
|---|---|---|
| 20 | 4.5 | 3.2 |
| 60 | 7.8 | 6.4 |
| 100 | 10.2 | 9.6 |
| 140 | 11.5 | 11.2 |
| 180 | 11.8 | 10.8 |
| 220 | 9.2 | 8.4 |
Explain why there is a direct link between the rate of photosynthesis and the dry biomass produced by the crop.
Identify the nitrogen concentration that produced the highest dry biomass.
Calculate the percentage increase in dry biomass when changing the nitrogen concentration from 20 mg L−1^{-1}−1 to 140 mg L−1^{-1}−1.
Suggest why the rate of photosynthesis and the dry biomass produced do not follow a perfectly proportional pattern across all nitrogen concentrations.
State three environmental factors, other than nitrogen concentration, that the facility must control to optimize the rate of photosynthesis and crop growth.
74 exam-style questions on Edexcel IGCSE Biology Food production. Each one has a worked solution and a mark scheme showing where the marks go.