AQA AS Biology Paper 1 2025 | Exam & Mark Scheme

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AS
BIOLOGY
Paper 1 N




Monday 12 May 2025 N N N Morning Time allowed: 1 hour 30 minutes
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Materials ForNExaminer’sNUse
For this paper you must have:
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Question Mark
 a ruler with millimetre measurements
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 a scientific calculator.
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Instructions 3
 Use black ink or black ball-point pen.
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 Fill in the boxes at the top of this page.
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 Answer all questions. N N
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 You must answer the questions in the spaces provided. Do not write
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outside the box around each page or on blank pages.
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 If you need extra space for your answer(s), use the lined pages at the end of
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this book. Write the question number against your answer(s).
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 Show all your working.N N N 9
 Do all rough work in this book. Cross through any work you do not want
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to be marked.
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Information
 The marks for the questions are shown in brackets.
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 The maximum mark for this paper is 75.
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Answer all questions in the spaces provided.
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0 1 . 1 N Figure 1 shows the structure of the amino acid alanine.
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Figure 1 N




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




COOH N




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




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




Type of bond
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N Type of molecule
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0 1 . 3 Table 1 shows the R groups of six different amino acids.
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Table 1 N




Amino acid
N R group
N Amino acid
N R group
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Alanine CH3 Glycine H

Aspartic acid
N 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
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Figure 2. N


[1 mark]
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Question 1 continues on the next page
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Turn over ►
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0 1 . 4 Figure 3 represents the structure of an antibody.
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Figure 3 N




The total number of amino acids in a particular antibody molecule is 1322
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The ratio of amino acids in the heavy chains to the amino acids in the light chains is
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2.13 : 1
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Calculate how many amino acids there are in one heavy chain.
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Give your answer to the nearest whole number.
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[2 marks]
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amino acids
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