The figure shows the leaves of two diseased plants, A and B.
Figure: The leaves of two diseased plants, A and B

Which leaf, A or B, is from the plant infected with tobacco mosaic virus?
Give one reason for your answer to part a).
Explain why a tomato plant infected with tobacco mosaic virus produces a smaller mass of tomatoes.
58 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.