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A-level
BIOLOGY
Paper 1
Thursday 4 June 2020 Morning Time allowed: 2 hours
Materials For Examiner’s Use
For this paper you must have:
• a ruler with millimetre measurements Question Mark
• a scientific calculator. 1
2
Instructions
3
• Use black ink or black ball-point pen.
• Fill in the boxes at the top of this page. 4
• Answer all questions. 5
• You must answer the questions in the spaces provided. Do not write 6
outside the box around each page or on blank pages.
7
• 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). 8
• Show all your working. 9
• Do all rough work in this book. Cross through any work you do not want
10
to be marked.
TOTAL
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 91.
*JUN207402101*
IB/M/Jun20/E16 7402/1
, 2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 Figure 1 shows a cell from the lining of the ileum specialised for absorption of
products of digestion.
SGLT1 is a carrier protein found in the cell-surface membrane of this cell, it transports
glucose and sodium ions (Na+) into the cell.
Figure 1
0 1 . 1 The action of the carrier protein X in Figure 1 is linked to a membrane-bound ATP
hydrolase enzyme.
Explain the function of this ATP hydrolase.
[2 marks]
0 1 . 2 The movement of Na+ out of the cell allows the absorption of glucose into the
cell lining the ileum.
Explain how.
[2 marks]
*02*
IB/M/Jun20/7402/1
, 3
Do not write
outside the
0 1 . 3 Describe and explain two features you would expect to find in a cell specialised for box
absorption.
[2 marks]
1
2
Question 1 continues on the next page
Turn over ►
*03*
IB/M/Jun20/7402/1
, 4
Do not write
outside the
Figure 2 is a diagram of one SGLT1 carrier protein. box
Figure 2
0 1 . 4 Draw phospholipids on Figure 2 to show how the carrier protein, SGLT1, would fit into
the cell-surface membrane.
Do not draw more than eight phospholipids.
[2 marks]
*04*
IB/M/Jun20/7402/1
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