Caffeine is a drug that decreases reaction time - AQA - GCSE Biology Combined Science - Question 5 - 2021 - Paper 2
Question 5
Caffeine is a drug that decreases reaction time.
A group of sixteen students investigated the effect of caffeine on reaction time.
The students were all 15-year-ol... show full transcript
Worked Solution & Example Answer:Caffeine is a drug that decreases reaction time - AQA - GCSE Biology Combined Science - Question 5 - 2021 - Paper 2
Step 1
Suggest one control variable the students should have used in the investigation.
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Answer
One control variable the students should have used in this investigation is the previous intake of caffeine that day.
Step 2
Suggest two sources of random error when using this method to measure a person's reaction time.
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Answer
Student A does not press both start buttons simultaneously.
Student B could be distracted while timing.
Step 3
Why can a mode not be determined for the data in Table 1?
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Answer
A mode cannot be determined for the data in Table 1 because all the values, results, or numbers are different.
Step 4
Describe how the students calculated the mean decrease in reaction time.
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Answer
The students calculated the mean decrease in reaction time by adding together all the decreases recorded for the 8 pairs and then dividing the total by the number of pairs (which is 8), excluding the anomalous result from pair 8 if required.
Step 5
Explain how the effect of adrenaline on heart rate may cause reaction time to decrease.
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Answer
Adrenaline increases heart rate, which raises blood flow. This results in more oxygen and glucose reaching the brain and muscles, improving their efficiency. Increased respiration also provides more energy, allowing for quicker muscle contraction, thereby decreasing reaction time.
Step 6
What is the name of the gap labelled X?
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The name of the gap labelled X is the synapse.
Step 7
Suggest why reaction time decreases when caffeine binds to adenosine receptors.
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Answer
Reaction time decreases when caffeine binds to adenosine receptors because fewer adenosine molecules can bind to the receptors, thus reducing their inhibitory effect on the relay neurones, leading to more frequent impulses and faster reaction times.
