In the pupil reflex, an impulse travels along a motor neurone to a muscle in the iris. The distance along this motor neurone is 0.030 m. In a patient with damaged myelin, the impulse speed along this motor neurone is 1.2 m/s. All other parts of the reflex pathway work normally.
Calculate the time taken for the impulse to travel along the motor neurone in the patient.
Explain how the damaged myelin affects the protection that the pupil reflex gives to the eye in bright light.
111 exam-style questions on Edexcel GCSE Biology 2.3 The nervous system and brain, covering 2.3.1 Structures and functions of the brain, 2.3.2 Imaging brain function with scanning, 2.3.3 Limitations in treating nervous system damage, 2.3.4 Neurones and impulse transmission, and 2.3.5 Structure and function of a reflex arc. Each one has a worked solution and a mark scheme showing where the marks go.