AS Level Biology AQA Paper 1 2025

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AS
BIOLOGY
Paper 1


Monday 12 May 2025 Morning Time allowed: 1 hour 30 minutes
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.
4
• Fill in the boxes at the top of this page.
• 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
TOTAL
to be marked.

Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 75.




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outside the
Answer all questions in the spaces provided. box




0 1 . 1 Figure 1 shows the structure of the amino acid alanine.

Figure 1




Name the NH2 and COOH groups in the amino acid.
[1 mark]

NH2

COOH


Figure 2 shows the molecule formed from alanine and another amino acid.

Figure 2




0 1 . 2 Name the type of bond and the type of molecule formed when the two amino acids in
Figure 2 are joined.
[2 marks]

Type of bond

Type of molecule




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0 1 . 3 Table 1 shows the R groups of six different amino acids. box



Table 1


Amino acid R group Amino acid R group

Alanine CH3 Glycine H

Aspartic acid CH2COOH Serine CH2OH

Glutamine (CH2)2CONH2 Valine CH(CH3)2


Use the information in Table 1 to identify the amino acid joined to alanine in
Figure 2.
[1 mark]




Question 1 continues on the next page




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0 1 . 4 Figure 3 represents the structure of an antibody. box



Figure 3




The total number of amino acids in a particular antibody molecule is 1322

The ratio of amino acids in the heavy chains to the amino acids in the light chains is
2.13 : 1

Calculate how many amino acids there are in one heavy chain.

Give your answer to the nearest whole number.
[2 marks]




amino acids 6




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