An optometrist tests a patient's eye before and after a medicine. The medicine has stopped one of the two sets of iris muscles from contracting. After the medicine, the patient can still focus clearly on a distant object.
| Light condition | Pupil diameter before the medicine | Pupil diameter after the medicine |
|---|---|---|
| 50 lux | 6.2 mm | 6.3 mm |
| 800 lux | 2.4 mm | 6.1 mm |
Use the results to explain which set of iris muscles has been affected and the effect this has on the eye. Suggest the changes that will occur in the eye when the patient then reads a page held close to their face.
135 exam-style questions on OCR GCSE Biology 3.1 Coordination and control – the nervous system, covering 3.1.1 Structure of the nervous system, 3.1.2 Coordinated response, 3.1.3 The reflex arc, 3.1.4 Structure of the eye, 3.1.5 Defects of the eye, 3.1.6 Structure and function of the brain, 3.1.7 Difficulties of investigating brain function, and 3.1.8 Limitations in treating nervous system damage. Each one has a worked solution and a mark scheme showing where the marks go.