MARK SCHEME JUNE 2025
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A-level
BIOLOGY
Paper 3
Wednesday 18 June 2025 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 in Section A. 5
• Answer one question from Section B. 6
• You must answer the questions in the spaces provided. Do not write
7
outside 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 of TOTAL
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 want
to be marked.
Information
• The marks for the questions are shown in brackets.
• The maximum mark for this paper is 78.
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, 3
Do not write
outside the
Section A box
Answer all questions in this section.
You are advised to spend no more than 1 hour and 15 minutes on this section.
0 1.1 Describe binary fission in bacteria.
[3 marks]
Question 1 continues on the next page
Turn over ►
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, 4
Do not write
outside the
0 1 . 2 Microbiologists investigated the effect of two temperatures on the population growth of a box
species of bacterium.
They grew separate bacterial cultures in identical nutrient media at 20 °C and 24 °C
for 8 hours.
Figure 1 shows the estimated final population size of each culture.
Figure 1
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