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
The students should have controlled the previous intake of caffeine that day to ensure it did not affect the results.
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 may not press both start buttons simultaneously, which could lead to timing discrepancies.
Either student could be distracted, affecting their ability to react accurately.
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 because all the values in Table 1 occur only once, meaning there is no value that appears more than once.
Step 4
Describe how the students calculated the mean decrease in reaction time.
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The students added the decrease in reaction times from the other seven pairs and then divided the total by 7 to find the mean.
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 enhances blood flow. This increases oxygen delivery to the brain and muscles, improving their responsiveness and resulting in a quicker reaction time.
Step 6
What is the name of the gap labelled X?
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Answer
Synapse.
Step 7
Suggest why reaction time decreases when caffeine binds to adenosine receptors.
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Answer
Caffeine binding to adenosine receptors prevents adenosine from signaling, leading to fewer inhibitory effects on the relay neurone, thus increasing the frequency of impulses and resulting in a quicker reaction time.
