2023 AQA A-level BIOLOGY 7402/3 Paper 3
Question Paper & Mark scheme (Merged) June
2023 [VERIFIED]
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A-level
BIOLOGY
Paper 3
Wednesday 21 June 2023 Morning Time allowed: 2 hours
Materials
For this paper you must have:
• a ruler with millimetre measurements
• a scientific calculator.
Instructions
• Use black ink or black ball-point pen.
• Fill in the boxes at the top of this page.
• Answer all questions in Section A.
• Answer one question from Section B.
• You must answer the questions in the spaces provided. Do not
write outside the box around each page or on blank pages.
• If you need extra space for your answer(s), use the lined pages at the end of
this book. Write the question number against your answer(s).
• Show all your working.
• Do all rough work in this book. Cross through any work you do not want
For Examiner’s Use
Question Mark
1
2
3
4
5
6
7
TOTAL
to be marked.
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 78.
2
Section A
Answer all questions in this section.
You are advised to spend no more than 1 hour and 15 minutes on this section.
0 1 . 1 Describe how stimulation of a Pacinian corpuscle produces a generator potential.
[3 marks]
Scientists investigated the stimulation of a Pacinian corpuscle in the skin of a fingertip.
The scientists applied two different pressures to the fingertip and recorded the
changes in membrane potential of the Pacinian corpuscle’s sensory neurone.
Figure 1 shows the scientists’ results.
Figure 1
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outside the
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0 1 . 2Use Figure 1 to describe what is meant by the all-or-nothing principle.
[2 marks]
0 1 . 3 On Figure 1, from 0.6 ms to 4.0 ms, no new generator potential could be produced.
What is this time period called?
[1 mark]
Turn over for the next question
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6
4
0 2A student investigated the effect of different sugars on the rate of respiration in yeast. Yeast
normally respires glucose.
Figure 2 shows the method she used for her first experiment.
Figure 2
0 2 . 1 Other than those stated, suggest two variables the student needed to keep constant in
her investigation.
[1 mark]
1
2
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Figure 3 shows the result she obtained for yeast in glucose solution.
Figure 3
0 2 . 2 Use Figure 2 and Figure 3 to calculate the rate of carbon dioxide production in
mm s
–1
for yeast in glucose solution.
Give your answer in standard form and to 2 significant figures.
Show your working.
[2 marks]
Do not write
outside the
box
Answer mm s–1
Turn over ►
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0 2 . 3 The student repeated the experiment using yeast in maltose solution. She found the rate
of carbon dioxide production was slower than with yeast in glucose solution.
Suggest why.
[2 marks]
0 2 . 4 A second student used a different method to investigate the effect of different sugars
on the rate of respiration in yeast.
He set up a tube with yeast in glucose solution and added bromothymol blue.
Bromothymol blue changes from blue to yellow when carbon dioxide is produced.
To determine the rate of respiration, he timed how long it took for the solution
to change from blue to yellow.
Suggest:
• why the method the second student used would be less accurate than
the method the first student used
• how the accuracy of the method the second student used could be improved.
[2 marks]
This method would be less accurate because
The accuracy of this method could be improved by
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outside the
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0 2 . 5 Complete the boxes A to D in Figure 4 to show the link reaction.
Fig [Show Less]