Rose black spot is caused by a fungus that infects rose leaves. A gardener collected and burned every fallen leaf under a rose bush each autumn. The following summer, fewer of the leaves on the bush were infected. Which explains this?
Fewer fungal spores were present to infect the new leaves
The bush made more antibacterial chemicals in its new leaves
The waxy cuticle of the new leaves was thicker and tougher
The bush grew a thicker layer of dead cells around its stems
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.