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hhhhThursday 5 June 2025 – Afternoon
uuuA Level Biology A
yyyyH420/01 Biological processes
pppTime allowed: 2 hours 15 minutes
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A-Level OCR 2025 Biology A Paper 1
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, 2
Section A
You should spend a maximum of 20 minutes on this section.
Write your answer to each question in the box provided.
1 Which option describes a function of inorganic ions?
A Ca2+ is pumped across the membrane of a neurone to establish the resting potential.
B Cl – and HCO3– are involved in transport of oxygen in the blood.
C Plants need NO3– for synthesis of amino acids.
D PO43− is a component of triglycerides.
Your answer [1]
2 Which option describes a conjugated protein?
A A globular protein with a prosthetic group
B A protein with an inorganic ion
C A protein with more than one polypeptide chain
D An enzyme with an inorganic ion
Your answer [1]
3 Which statement about the function of enzymes is not correct?
A Enzymes affect the structure of whole organisms.
B Enzymes build larger molecules from smaller molecules.
C Enzymes carry signals from one part of the body to another.
D Enzymes catalyse reactions that affect cellular metabolism.
Your answer [1]
© OCR 2025
, 3
4 Which option describes the structure of biological molecules?
A Carbohydrates contain only C, H and O, usually with an H to O ratio of 2 : 1.
B Nucleic acids contain only C, H, O, N, P and S in variable ratios.
C Proteins contain only C, H, O and N in variable ratios.
D Triglycerides contain only C, H and O, usually with an H to O ratio of 2 : 1.
Your answer [1]
5 Which option describes endocrine communication?
A Endocrine glands release hormones into ducts such as the pancreatic duct.
B Hormones are all lipid soluble and bind to receptors in the cytoplasm.
C Hormones are released from exocrine glands and taken by the blood to specific target cells.
D Target cells have specific receptors for the hormones that act upon them.
Your answer [1]
6 Which option describes a role of the adrenal glands within the endocrine system?
A Adrenaline is produced by the adrenal cortex.
B Glucocorticoids help to regulate the balance of salt and water concentrations in the body.
C Mineralocorticoids are produced in the adrenal medulla.
D The adrenal cortex secretes steroid hormones.
Your answer [1]
© OCR 2025 Turn over
, 4
A student investigates the growth of yeast cells in culture under different conditions.
In experiment one they grow yeast cells with glucose at 25 °C. The results are shown as line X on the
graph.
In experiment two they grow yeast cells under different conditions. The results are shown as lines A to
D on the graph.
9
A B X
8
Log10 number
of cells 7 C
6
D
5
0 200 400 600 800 1000
Time (min)
Use the information to answer questions 7 and 8.
7 In experiment one, what is the number of cells in the culture after 10 hours?
A 0.9 × 107
B 4.0 × 107
C 7.6
D 7.6 × 107
Your answer [1]
8 Which line, A to D, in experiment two represents a culture where the growth rate is approximately
double that in experiment one?
Your answer [1]
© OCR 2025
Oxford Cambridge and RSAttttttttkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk
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hhhhThursday 5 June 2025 – Afternoon
uuuA Level Biology A
yyyyH420/01 Biological processes
pppTime allowed: 2 hours 15 minutes
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A-Level OCR 2025 Biology A Paper 1
Hhhhh buhuefhfe efuehfuef uefeufhef hhief jhiihfe hihi jhh jhjhjhjh jhjhjh jkl kl vgvtdr
, 2
Section A
You should spend a maximum of 20 minutes on this section.
Write your answer to each question in the box provided.
1 Which option describes a function of inorganic ions?
A Ca2+ is pumped across the membrane of a neurone to establish the resting potential.
B Cl – and HCO3– are involved in transport of oxygen in the blood.
C Plants need NO3– for synthesis of amino acids.
D PO43− is a component of triglycerides.
Your answer [1]
2 Which option describes a conjugated protein?
A A globular protein with a prosthetic group
B A protein with an inorganic ion
C A protein with more than one polypeptide chain
D An enzyme with an inorganic ion
Your answer [1]
3 Which statement about the function of enzymes is not correct?
A Enzymes affect the structure of whole organisms.
B Enzymes build larger molecules from smaller molecules.
C Enzymes carry signals from one part of the body to another.
D Enzymes catalyse reactions that affect cellular metabolism.
Your answer [1]
© OCR 2025
, 3
4 Which option describes the structure of biological molecules?
A Carbohydrates contain only C, H and O, usually with an H to O ratio of 2 : 1.
B Nucleic acids contain only C, H, O, N, P and S in variable ratios.
C Proteins contain only C, H, O and N in variable ratios.
D Triglycerides contain only C, H and O, usually with an H to O ratio of 2 : 1.
Your answer [1]
5 Which option describes endocrine communication?
A Endocrine glands release hormones into ducts such as the pancreatic duct.
B Hormones are all lipid soluble and bind to receptors in the cytoplasm.
C Hormones are released from exocrine glands and taken by the blood to specific target cells.
D Target cells have specific receptors for the hormones that act upon them.
Your answer [1]
6 Which option describes a role of the adrenal glands within the endocrine system?
A Adrenaline is produced by the adrenal cortex.
B Glucocorticoids help to regulate the balance of salt and water concentrations in the body.
C Mineralocorticoids are produced in the adrenal medulla.
D The adrenal cortex secretes steroid hormones.
Your answer [1]
© OCR 2025 Turn over
, 4
A student investigates the growth of yeast cells in culture under different conditions.
In experiment one they grow yeast cells with glucose at 25 °C. The results are shown as line X on the
graph.
In experiment two they grow yeast cells under different conditions. The results are shown as lines A to
D on the graph.
9
A B X
8
Log10 number
of cells 7 C
6
D
5
0 200 400 600 800 1000
Time (min)
Use the information to answer questions 7 and 8.
7 In experiment one, what is the number of cells in the culture after 10 hours?
A 0.9 × 107
B 4.0 × 107
C 7.6
D 7.6 × 107
Your answer [1]
8 Which line, A to D, in experiment two represents a culture where the growth rate is approximately
double that in experiment one?
Your answer [1]
© OCR 2025
