A conservation worker finds purple-black spots on the leaves of wild rose plants. The affected leaves later turn yellow and drop from the plants.
Which is the most likely cause of these changes to the leaves?
A bacterium infecting the rose leaves
A virus infecting the rose leaves
A fungus infecting the rose leaves
An aphid feeding on the plant's sap
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.