Question Constellation Sign up for free AQA · GCSE · Biology · Higher
Synaptic transmission and reaction time
The scientists gave the hypothesis:
‘Optimum blood glucose concentration increases the production of chemicals that diffuse across synapses.’
Describe how an increase in the chemicals could decrease reaction time.
Write your answer first. You can study the marking guidance whenever you need it.
Study the marking See what earns credit and compare it with a full-mark answer.
Marking points
- 1 Explains faster chemical diffusion across the synapse.
- 2 Explains an increased likelihood/speed/strength/number of impulses in the next neurone.
- 3 Explains that an impulse reaches the muscle more readily or quickly, or causes faster contraction.
Full-mark answer
A higher concentration of neurotransmitter diffuses across each synapse faster. This makes an impulse in the next neurone more likely, so the impulse reaches the muscle sooner and the muscle contracts sooner, reducing reaction time.
Why this answer loses marks
The signal travels faster.
“Signal” alone is ignored; link extra neurotransmitter to diffusion and an impulse in the next neurone or reaching the muscle.