Label the following diagram of the eye.

Outline how the pupil reflex can be used to indicate brain death.

The diagram below shows a synapse where the neurotransmitter is dopamine and some of the processes that take place during nerve transmission.  

Explain the effect of cocaine on neurotransmission at a synapse.

I iris
II vitreous humour
III choroid
IV fovea (do not accept yellow spot)
Award [1] for every two correct answers.

a. pupil normally constricts when light is shone on it;
b. light detected in the retina and impulse sent to brain;
c. lack of (motor) response indicates no brain processing taking place/brain death;

a. dopamine initiates depolarization of post-synaptic membrane;
b. cocaine binds to (transporter) carrier proteins/proteins in pre-synaptic membrane;
c. cocaine blocks reabsorption (of dopamine);
d. cocaine causes dopamine build up in synaptic cleft/space;
e. so stimulus continues/cocaine is excitatory;

It was disappointing how many candidates could not label the diagram of the eye correctly. 

Although many were able to get 1 mark for understanding that a lack of pupil response to light indicated no brain processing and therefore brain death, few were able to get a second mark. Many were using incorrect terminology to describe what happened to the pupil in response to light. A persistent misconception seemed to be that the pupil "detects" light and not the retina.  

In general, candidates did poorly on this question with many only getting one mark. Many were incorrectly saying cocaine is a neurotransmitter or that it caused more dopamine to be produced rather than it caused dopamine build up in the synaptic cleft due the fact it blocks the reabsorption of dopamine. Many were relying on general ‘street’ knowledge rather than any biological information.