Lysozyme is an enzyme found in tears, saliva and mucus.
A student wrote:
"Lysozyme protects the eye by trapping bacteria so they can be washed away."
Explain why the student is wrong.
Some people make fewer tears than normal.
Explain why these people are more likely to get eye infections.
Explain why lysozyme can kill bacteria but does not damage human cells.
Lysozyme does not destroy viruses.
Suggest why.
45 exam-style questions on Edexcel GCSE Biology 5.2 Plant and body defences, covering 5.2.1 Physical plant defences, 5.2.2 Chemical plant defences, 5.2.3 Detecting plant diseases, and 5.2.4 Human physical and chemical defences. Each one has a worked solution and a mark scheme showing where the marks go.