The figure shows the junction between two neurones, P and Q.
Figure: The junction between two neurones

Name the gap labelled X.
Describe how an impulse is passed from neurone P to neurone Q.
A drug blocks the receptors on neurone Q.
Suggest the effect of this drug on the reflex action.
4 exam-style questions on AQA GCSE Biology 5.2.1 Structure and function. Each one has a worked solution and a mark scheme showing where the marks go.