A researcher monitored primrose plants in four areas of a woodland. Yellow patches were first observed on leaves in area A.
The table shows the percentage of primrose plants with yellow patches.
| Area | Distance from area A in m | Day 0 | Day 14 | Day 28 |
|---|---|---|---|---|
| A | 0 | 40% | 70% | 90% |
| B | 10 | 0% | 25% | 60% |
| C | 20 | 0% | 0% | 30% |
| D | 40 | 0% | 0% | 0% |
Soil tests on day 0 and day 28 showed that the primrose plants did not have a shortage of magnesium ions.
Explain how the results support the conclusion that the yellow patches are caused by a communicable disease rather than by magnesium deficiency.
Explain why these results cannot identify the exact pathogen. Suggest a suitable method for finding out, within a few minutes in the woodland, whether one particular pathogen is present. Explain why the method is suitable.
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.