A scientist investigated the effect of the waxy cuticle on bacterial infection in sunflower plants.
The scientist used a method to remove the waxy cuticle without damaging the leaf cells. All the plants were sprayed with the same bacterial suspension and kept under the same conditions.
| Group | Treatment of leaves | Number of plants | Number of plants infected after 10 days |
|---|---|---|---|
| 1 | Waxy cuticle left unchanged | 50 | 4 |
| 2 | Waxy cuticle removed | 50 | 37 |
Calculate the difference, in percentage points, between the percentages of plants infected in the two groups.
Explain why more plants were infected in group 2 and why some plants in group 1 were still infected.
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.