The leaves of some of the lettuce plants in a large field have pale spots on them. The other plants in the field look healthy. The farmer wants to know what is causing the spots.
Describe how the farmer could detect and identify the cause of the pale spots, and explain why it is important to do this quickly.
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.