A scientist grew three groups of radish seedlings for four weeks. All conditions were identical except for the concentration of magnesium ions in the nutrient solution.
The increase in dry mass was used as a measure of growth.
| Magnesium ion concentration in mg/dm³ | Mean chlorophyll content in mg per g of leaf | Mean increase in dry mass in g | Leaf colour |
|---|---|---|---|
| 0 | 0.42 | 0.68 | yellow |
| 25 | 1.18 | 1.92 | green |
| 50 | 1.22 | 1.95 | green |
Explain the results in the table.
The scientist divided the seedlings that had received no magnesium ions into two groups. The scientist grew both groups for another two weeks.
| Treatment during the next two weeks | Mean chlorophyll content in mg per g of leaf | Mean increase in dry mass during the two weeks in g |
|---|---|---|
| Magnesium ions added | 1.10 | 0.72 |
| No magnesium ions added | 0.35 | 0.20 |
Explain why these results support the conclusion that the yellow leaves were caused by a non-communicable disorder rather than by a pathogen.
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.