A horticultural researcher grows groups of young bean plants in pots of compost. Each group is watered with the same volume of solution, but the solutions contain different concentrations of nitrate ions. After 21 days, the researcher measures the mean dry mass of the whole plant in each group.
| Nitrate ion concentration in the watering solution (mg/dm³) | Mean dry mass of a whole plant (g) |
|---|---|
| 10 | 2.1 |
| 25 | 3.4 |
| 50 | 4.6 |
| 100 | 5.3 |
Give the nitrate ion concentration that produced the greatest mean dry mass.
Explain how the availability of nitrate ions could affect the growth of the plants.
133 exam-style questions on AQA GCSE Biology 3.3 Plant disease, covering 3.3.1 Detection and identification of plant diseases and 3.3.2 Plant defence responses. Each one has a worked solution and a mark scheme showing where the marks go.