Scientists allowed aphids to feed on sweet pepper plants. While the aphids were feeding, the scientists collected liquid flowing through their mouthparts. They compared this liquid with sap taken from two tissues in the plants.
| Sample | Concentration of dissolved sugars in mg/cm³ | Concentration of mineral ions in mg/cm³ |
|---|---|---|
| Sap from xylem | 0.4 | 2.8 |
| Sap from phloem | 180 | 0.9 |
| Liquid from aphid mouthparts | 172 | 1.0 |
From which tissue did the aphids feed? Use both concentration measurements in the table to support your answer.
Explain why feeding by large numbers of aphids could reduce the increase in dry mass of the sweet pepper plants.
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.