Bark is made of layers of dead cells around the stem of a tree. The outer bark flakes off as the tree grows. Which statement best explains how the flaking of bark defends the tree against disease?
The new bark underneath contains antibacterial chemicals
Flaking bark exposes living cells that can fight infection
Flaking bark makes the stem too rough for insects to feed
Pathogens on the dead outer layers are shed with the bark
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.