DP Biology (last assessment 2024)
Question 18M.3.HL.TZ2.7b
| Date | May 2018 | Marks available | [Maximum mark: 1] | Reference code | 18M.3.HL.TZ2.7b |
| Level | HL | Paper | 3 | Time zone | TZ2 |
| Command term | State | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 1]
18M.3.HL.TZ2.7b
An organism’s diminished response to a repeated stimulus is referred to as habituation. The diagrams show the experiments performed on habituation to a stimulus in a sea slug (Aplysia californica). The sea slug is a mollusc that has an external gill for gas exchange. If the siphon of the sea slug is stimulated mechanically, it withdraws the gill in a simple reflex action.
(b)
With reference to the experiments on habituation, state the effect of repeated stimulation on the level of neurotransmitter in the synapses.
[1]
Markscheme
less neurotransmitters/dopamine are released «to the synaptic cleft by presynaptic interneurons»
