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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 1
Thursday 4 June 2026 Afternoon Time allowed: 2 hours
Materials For Examiner’s Use
For this paper you must have:
Question Mark
• a ruler with millimetre measurements
• 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.
*jun267402101*
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2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 Figure 1 shows a molecule of antidiuretic hormone (ADH).
Figure 1
The ADH molecule is made up of nine amino acids joined by peptide bonds.
0 1 . 1 Use information in Figure 1 to describe two other structural features of ADH.
[2 marks]
1
2
*02*
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3
Do not write
outside the
0 1 . 2 Name the biochemical test used to detect ADH in a solution. box
Describe the positive result.
[2 marks]
Name of test
Positive result
ADH is produced when enzymes hydrolyse the preproprotein, AVP. This hydrolysis
produces three smaller polypeptides, ADH, Copeptin and NPII.
0 1 . 3 A scientist determined that ADH contains 6.38% of the amino acids in an AVP
preproprotein. He counted 39 amino acids in the Copeptin protein.
Calculate the number of amino acids in the NPII polypeptide.
Use Figure 1 to help you answer this question.
[1 mark]
Answer
0 1 . 4 The hydrolysis of AVP by these enzymes always produces ADH, Copeptin and
NPII polypeptides.
Explain why.
[2 marks]
7
Turn over for the next question
Turn over ►
*03*
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4
Do not write
outside the
0 2 . 1 Explain why the genetic code is described as universal and degenerate. box
[2 marks]
Universal
Degenerate
Table 1 shows information about the genome of a human sperm cell.
Table 1
Log10 (total number of nucleotide pairs) 9.5
Percentage of nucleotide pairs not coding for polypeptide 98.5
Total number of genes coding for polypeptides 20 000
0 2 . 2 Use information in Table 1 to calculate the mean number of nucleotide pairs coding
for a polypeptide per gene in a sperm cell.
Show your working.
[3 marks]
Answer
0 2 . 3 What term is used to describe nucleotide pairs within a gene that do not code for an
amino acid sequence?
[1 mark]
*04*
IB/M/Jun26/7402/1
Check Out ExamLab For More Resources : https://www.stuvia.com/user/examlab
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 1
Thursday 4 June 2026 Afternoon Time allowed: 2 hours
Materials For Examiner’s Use
For this paper you must have:
Question Mark
• a ruler with millimetre measurements
• 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.
*jun267402101*
Check Out ExamLab For More Resources : IB/M/Jun26/G4005/V13 7402/1
https://www.stuvia.com/user/examlab
,Check Out ExamLab For More Resources : https://www.stuvia.com/user/examlab
2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1 Figure 1 shows a molecule of antidiuretic hormone (ADH).
Figure 1
The ADH molecule is made up of nine amino acids joined by peptide bonds.
0 1 . 1 Use information in Figure 1 to describe two other structural features of ADH.
[2 marks]
1
2
*02*
IB/M/Jun26/7402/1
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3
Do not write
outside the
0 1 . 2 Name the biochemical test used to detect ADH in a solution. box
Describe the positive result.
[2 marks]
Name of test
Positive result
ADH is produced when enzymes hydrolyse the preproprotein, AVP. This hydrolysis
produces three smaller polypeptides, ADH, Copeptin and NPII.
0 1 . 3 A scientist determined that ADH contains 6.38% of the amino acids in an AVP
preproprotein. He counted 39 amino acids in the Copeptin protein.
Calculate the number of amino acids in the NPII polypeptide.
Use Figure 1 to help you answer this question.
[1 mark]
Answer
0 1 . 4 The hydrolysis of AVP by these enzymes always produces ADH, Copeptin and
NPII polypeptides.
Explain why.
[2 marks]
7
Turn over for the next question
Turn over ►
*03*
IB/M/Jun26/7402/1
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4
Do not write
outside the
0 2 . 1 Explain why the genetic code is described as universal and degenerate. box
[2 marks]
Universal
Degenerate
Table 1 shows information about the genome of a human sperm cell.
Table 1
Log10 (total number of nucleotide pairs) 9.5
Percentage of nucleotide pairs not coding for polypeptide 98.5
Total number of genes coding for polypeptides 20 000
0 2 . 2 Use information in Table 1 to calculate the mean number of nucleotide pairs coding
for a polypeptide per gene in a sperm cell.
Show your working.
[3 marks]
Answer
0 2 . 3 What term is used to describe nucleotide pairs within a gene that do not code for an
amino acid sequence?
[1 mark]
*04*
IB/M/Jun26/7402/1
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