A pharmacist is testing whether a new medicine affects communication between neurones. Fig. 1 shows a synapse, the tiny gap between the ending of one neuron...
Question 1 Report
A pharmacist is testing whether a new medicine affects communication between neurones. Fig. 1 shows a synapse, the tiny gap between the ending of one neurone and the next cell. In the test, the medicine prevents some neurotransmitter molecules from binding to receptor molecules.
(a) Name the gap between the two neurones shown in Fig. 1. [1]
(b) Name the chemical released from the end of the first neurone. [1]
(c) Explain how preventing neurotransmitter binding could reduce the number of impulses in the next neurone. [3]
(d) Describe two features of a synapse that allow transmission in only one direction. [2]
(e) State one reason why testing this medicine on isolated cells before testing it in a person is useful. [1]
Answer Details
(a) The gap is the synapse, also called the synaptic cleft. [1]
(b) The chemical released from the first neurone is a neurotransmitter. [1]
(c) If fewer neurotransmitter molecules bind to receptors, fewer ion channels open and the next neurone is less likely to depolarise. Its threshold is reached less often, so fewer nerve impulses are produced. [3]
(d) Neurotransmitter-containing vesicles that release transmitter occur only at the end of the first neurone. Receptor molecules occur only on the membrane of the next neurone. These arrangements make transmission one-way. [2]
(e) Testing isolated cells can identify an effect or toxicity before a person is exposed to unnecessary risk. [1]
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