A researcher investigates eye drops that reduce contraction in one of the two sets of muscles in the iris.
The pupil diameter of the same person is measured after the eye has adjusted to each light intensity.
| Eye drops used | Light intensity in lx | Pupil diameter in mm |
|---|---|---|
| no | 800 | 2.0 |
| no | 5 | 6.0 |
| yes | 800 | 2.0 |
| yes | 5 | 3.0 |
Calculate the percentage change in pupil diameter caused by the eye drops at 5 lx.
Explain which set of iris muscles is affected by the eye drops and how the activity of both sets of muscles produces the result at 5 lx.
Suggest whether the eye drops provide extra protection against damage to the retina at 800 lx. Use the results in your answer.
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.