The Figure shows a section through the human eye.
Figure

Name structures P and R.
Describe the function of structure Q.
Explain how structures P and R help to produce a clear image.
State the function of structure S.
102 exam-style questions on Edexcel GCSE Biology 2.4 The eye, covering 2.4.1 Structure and function of the eye and 2.4.2 Eye defects and their correction. Each one has a worked solution and a mark scheme showing where the marks go.