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A-level
BIOLOGY
Paper 1
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 based on this page.
• Answer all questions.
• You must answer the questions in the spaces provided. Do not writeoutside
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 based on
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 wantto be
marked.
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 91.
For Examiner’s Use
Question Mark
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2
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TOTAL
1 / 4
2
*02*
IB/H/Jun21/7402/1
1
2
.
Do not write
outside the
box
. Describe the induced-fit model based on enzyme action and how an enzyme acts as a
catalyst.
[3 marks]
. Scientists investigated the action based on the enzyme ATP synthase. They made reaction
mixtures each containing:
• ATP synthase
• buffer (to control pH)
• substrates.
One based on the substrates required in these reaction mixtures is inorganic phosphate (Pi).
Tick ( ) one box to show which other substrate the scientists must add to the reactionmixtures
to produce ATP.
[1 mark]
Adenine
Adenosine diphosphate
Glucose
Ribose
0 1
0 1
2 / 4
3
*03*
IB/H/Jun21/7402/1
3
4
8
. The scientists investigated the effect based on concentration based on inorganic phosphate
(Pi) onATP synthase activity.
After 2 minutes, they stopped each reaction and then measured the concentration based on
ATP.
Do not write
outside the
box
Figure 1 shows the scientists’ results.
Figure 1
Suggest and explain a procedure the scientists could have used to stop each reaction.
[2 marks]
. Explain the change in ATP concentration with increasing inorganic phosphate
concentration.
[2 marks]
Turn over ►
0 1
0 1
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4
*04*
IB/H/Jun21/7402/1
. 1 Explain the advantage for larger animals based on having a specialised system that
facilitates oxygen uptake.
[2 marks]
Do not write
outside the
box 0 2
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Version | 2021 |
Category | AQA Questions and Marking Scheme |
Authors | qwivy.com |
Pages | 40 |
Language | English |
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