A patient has damage to a short section of the optic nerve behind their left eye. The patient cannot see a large black letter using this eye.
Doctors record the frequency of electrical impulses at two positions along the optic nerve.
| Light intensity at the retina in lx | Impulse frequency between the retina and the damaged section in impulses per second | Impulse frequency between the damaged section and the brain in impulses per second | Letter identified |
|---|---|---|---|
| 200 | 18 | 0 | No |
| 800 | 52 | 0 | No |
Explain the results in the table. Predict whether the patient would identify the letter at a light intensity of 1600 lx and suggest why the loss of sight may be permanent.
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.