Question 19M.3.SL.TZ2.7
| Date | May 2019 | Marks available | [Maximum mark: 4] | Reference code | 19M.3.SL.TZ2.7 |
| Level | SL | Paper | 3 | Time zone | TZ2 |
| Command term | Explain | Question number | 7 | Adapted from | N/A |
Explain the autonomic control of the pupil of the eye and how the pupil reflex is used to determine brain damage.
[4]
a. iris sphincter muscle / circular muscle / pupil constriction is controlled by the parasympathetic system ✔
b. iris dilator / radial muscle / pupil dilation is controlled by the sympathetic system ✔
c. at low light intensity pupil dilates
OR
at high intensity it constricts
OR
a reflex that controls the diameter of the pupil in response to intensity of light entering the eye ✔
d. «under normal conditions» pupils of both eyes respond identically to a light stimulus «regardless of which eye is being stimulated» ✔
e. response in one pupil without the other pupil responding is sign of a problem ✔
f. delayed response may indicate damage to brain / optic nerve / problems in oculomotor nerve/brain stem / use of depressant drugs / brain death ✔
Accept no response
Most candidates scored two marks for explaining the autonomic control of the pupil of the eye and how the pupil reflex is used to determine brain damage. The main error was mixing up the two autonomic systems. The answers were often scattered and confused.
