A grower recorded the increase in height of sunflower plants over 7 days.
| Plant group | Mean increase in height in 7 days (cm) |
|---|---|
| Healthy plants | 10.8 |
| Diseased plants | 2.6 |
The grower then investigated how often plants should be inspected for disease. Two growth rooms each contained 60 sunflower plants. The rooms had the same environmental conditions.
On day 0, one plant in each room was infected with the same pathogen. Plants showing signs of disease were removed when they were detected.
| Growth room | Inspection interval | Day the disease was first detected | Total number of plants that had shown signs by day 15 |
|---|---|---|---|
| R | Every day | 1 | 6 |
| S | Every 5 days | 5 | 30 |
Using the data, identify the sign of disease shown by the diseased sunflower plants.
Use calculations to explain why the results support inspecting the plants every day.
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.