A temporary treatment prevents the radial muscles in a person's iris from contracting but does not affect the circular muscles.
The pupil diameter is measured at two light intensities before and after the treatment.
| Treatment | Pupil diameter at 600 lux in mm | Pupil diameter at 5 lux in mm |
|---|---|---|
| before treatment | 2.2 | 6.4 |
| after treatment | 2.3 | 2.9 |
Explain how the treatment changes the pupil response and how this affects the amount of light reaching the retina at 5 lux.
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.