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A-Level OCR 2025 Biology B Paper 1

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A-Level OCR 2025 Biology B Paper 1 Fundamentals of biology

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Oxford Cambridge and RSA

Thursday 5 June 2025 – Afternoon
A Level Biology B (Advancing Biology)
H422/01 Fundamentals of biology
Time allowed: 2 hours 15 minutes

You must have:
• a ruler (cm/mm)
You can use:
• a scientific or graphical calculator




Please write clearly in black ink. Do not write in the barcodes.

Centre number Candidate number


Revision303 First name(s) Revision303 Revision303
Last name


INSTRUCTIONS
• Use black ink. You can use an HB pencil, but only for graphs and diagrams.
• Write your answer to each question in the space provided. If you need extra space use
the lined pages at the end of this booklet. The question numbers must be clearly shown.
• Answer all the questions.
• Where appropriate, your answer should be supported with working. Marks might be
given for using a correct method, even if your answer is wrong.

INFORMATION
• The total mark for this paper is 110.
• The marks for each question are shown in brackets [ ].
• Quality of extended response will be assessed in questions marked with an asterisk (*).
• This document has 44 pages.

ADVICE
• Read each question carefully before you start your answer.




Turn over



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2
Section A

You should spend a maximum of 40 minutes on this section.

Write your answer for each question in the box provided.

1 Which type of blood cell is shown in the annotated drawing?

Non-granulated cytoplasm




Kidney-bean shaped nucleus




A Erythrocyte

B Lymphocyte

C Monocyte

D Neutrophil

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Your answer
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[1]



2 Which technique uses fluorescent markers to tag cells so they can be counted and identified
when passed through a laser beam?

A Differential staining

B Flow cytometry

C Gel electrophoresis

D Haemocytometry

Your answer [1]




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3
3 Which statement about ATP is not correct?

A It can be hydrolysed to form AMP.

B It contains the pentose sugar, ribose.

C It contains the pyrimidine nitrogenous base, adenine.

D It is a phosphorylated nucleotide.

Your answer [1]



4 The percentage base composition of DNA from a species of octopus is shown in the table.

Base Adenine X Y Z
% base composition 33.2 17.6 17.5 31.7
of DNA


Which option correctly identifies bases X, Y and Z?

A Base X is cytosine, Y is guanine and Z is thymine.

B Base X is cytosine, Y is guanine and Z is uracil.

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C Base X is thymine, Y is cytosine and Z is guanine. Revision303
D Base X is uracil, Y is cytosine and Z is guanine.

Your answer [1]



5 A student calculated cardiac output (CO) using the equation:

CO = heart rate × stroke volume.

What unit of measurement is appropriate for cardiac output?

A bpm cm–3

B cm3 bpm

C dm–3 min–1

D dm3 min–1

Your answer [1]




Turn over



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4
6 Which of the following statements about the advantages of a closed circulatory system is/are
correct?

1 Deoxygenated and oxygenated blood are separated.

2 Higher blood pressure is maintained in both pulmonary and systemic circuits.

3 Low blood volumes can maintain movement in the circulatory system.


A 1, 2 and 3 are correct

B Only 1 and 2 are correct

C Only 2 and 3 are correct

D Only 1 is correct

Your answer [1]



7 Alveoli are structures found in the mammalian gaseous exchange system.

Which cells would be present in the walls of alveoli?

A Ciliated epithelial cells
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B Goblet cells

C Muscle cells

D Squamous epithelial cells

Your answer [1]



8 The surface area provided by a single alveolus is approximately 300 000 μm2.

A person was estimated to have 250 million alveoli in each lung.

What is the estimated gas exchange surface area in m2 for this person?

A 7.5 × 101

B 1.5 × 102

C 7.5 × 107

D 1.5 × 108

Your answer [1]




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Información del documento

Nivel de Estudio
Tema
Subido en
25 de noviembre de 2025
Número de páginas
37
Escrito en
2025/2026
Tipo
Examen
Contiene
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