What is a feature of neurons?
A. Relay neurons transmit impulses from motor to sensory neurons.
B. The cell body of a motor neuron is in the CNS.
C. Sensory neurons carry impulses away from the CNS.
D. Relay neurons form synapses with receptors.

B

This was a very badly answered question with less than 20% of candidates answering it correctly. This is lower than the expected 25% success rate from guessing. Some teachers felt that it was not part of the HL program, but the correct answer could be deduced from Assessment Statements 6.5.2 and 6.5.3 and the answer could also be identified by eliminating the three distractors using understanding gained from these Assessment statements. Students who had studied Option E were at a slight advantage. Every effort is made to avoid advantages in Paper 1 for those who have studied a particular Option, but in some cases where the Option amplifies part of the Core or AHL it is almost inevitable. The commonest answer was D, which was the incorrect statement that relay neurons form synapses with receptors, but many candidates also chose A which stated that relay neurons transmit impulses from motor to sensory neurons. At least some candidates will have misread the question and chosen it without going on to read the other choices.