AQA
A-level
BIOLOGY
7402/3
Paper 3
Version: 1.0 Final
*jun237402301*
IB/M/Jun23/E12 7402/3
For Examiner’s Use
Question
... [Show More] Mark
1
2
3
4
5
6
7
TOTAL
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
to be marked.
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 78.
Please write clearly in block capitals.
Centre number Candidate number
Surname
Forename(s)
Candidate signature
I declare this is my own work.
A-level
BIOLOGY
Paper 3
2
*02*
IB/M/Jun23/7402/3
Do not write
outside the
Section A box
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
3
*03*
Turn over ►
IB/M/Jun23/7402/3
Do not write
outside the
box 0 1 . 2 Use 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
6
4
*04*
IB/M/Jun23/7402/3
Do not write
outside the
box 0 2 A 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
5
*05*
Turn over ►
IB/M/Jun23/7402/3
Do not write
outside the
box 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]
Answer mm s–1
6
*06*
IB/M/Jun23/7402/3
Do not write
outside the
box 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 [Show Less]