A farmer finds that potato plants in three fields have yellow leaves and stunted growth.
Samples of plants and soil from each field were sent to a laboratory. The plants were tested for virus V.
The Table shows the results.
Table
| Field | Soil water content | Soil nitrate concentration | Percentage of plants with symptoms | Result of test for virus V |
|---|---|---|---|---|
| 1 | normal | normal | 34 | positive |
| 2 | normal | low | 30 | negative |
| 3 | normal | normal | 2 | negative |
Explain why the soil water content and soil nitrate concentration were measured.
Explain what the results show about the cause of the symptoms in field 1 and in field 2.
Suggest two ways the laboratory could increase confidence in the result for field 1.
45 exam-style questions on Edexcel GCSE Biology 5.2 Plant and body defences, covering 5.2.1 Physical plant defences, 5.2.2 Chemical plant defences, 5.2.3 Detecting plant diseases, and 5.2.4 Human physical and chemical defences. Each one has a worked solution and a mark scheme showing where the marks go.