AQA A-level Biology – Practice Examination Paper 3
newest 2026 Questions + Examiner-Approved
Solutions | A+ Booster Pack”
Paper 3 (Synoptic Essay & Practical Applications)
Level: Year 13 (Advanced)
Total Marks: 91
Time Allowed: 2 hours
Instructions
• Answer all questions.
• Write your answers in black ink or ball-point pen.
• Use a pencil for graphs and diagrams.
• Show all your working for calculations.
• You may use a calculator.
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 91.
Section A: Short Answer Questions
Q1
(a) Define the term primary structure of a protein. (1)
Answer: The sequence/order of amino acids in a polypeptide chain.
,(b) Explain how hydrogen bonds contribute to the secondary structure of proteins.
(2)
Answer: Hydrogen bonds form between the –NH and –CO groups in
the backbone; these stabilize structures such as alpha helices and beta
pleated sheets.
Q2
A student investigated enzyme activity at different temperatures.
Temperature (°C) Rate of reaction (arbitrary units)
10 5
20 12
30 20
40 25
50 10
(a) Describe the trend shown in the table. (2)
Answer: Rate increases with temperature up to 40°C, then decreases
sharply at 50°C.
(b) Explain the decrease in rate at 50°C. (2)
Answer: Enzyme denatures; active site changes shape; substrate no
longer fits.
Q3
, (a) Describe two differences between prokaryotic and eukaryotic cells. (2)
Answer: Prokaryotes lack membrane-bound organelles; DNA is
circular and not in a nucleus.
(b) Name one organelle involved in protein synthesis. (1)
Answer: Ribosome.
Q4
(a) State the function of cholesterol in cell membranes. (1)
Answer: Maintains membrane fluidity/stability.
(b) Explain how facilitated diffusion differs from active transport. (2)
Answer: Facilitated diffusion is passive and down a concentration
gradient; active transport requires ATP and moves substances against
a gradient.
Q5
(a) Define diffusion. (1)
Answer: Net movement of particles from high to low concentration.
(b) Suggest two adaptations of alveoli for efficient gas exchange. (2)
Answer: Large surface area; thin walls (short diffusion distance).
Q6
(a) State the role of ATP in cells. (1)
Answer: Immediate energy source for cellular processes.
newest 2026 Questions + Examiner-Approved
Solutions | A+ Booster Pack”
Paper 3 (Synoptic Essay & Practical Applications)
Level: Year 13 (Advanced)
Total Marks: 91
Time Allowed: 2 hours
Instructions
• Answer all questions.
• Write your answers in black ink or ball-point pen.
• Use a pencil for graphs and diagrams.
• Show all your working for calculations.
• You may use a calculator.
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 91.
Section A: Short Answer Questions
Q1
(a) Define the term primary structure of a protein. (1)
Answer: The sequence/order of amino acids in a polypeptide chain.
,(b) Explain how hydrogen bonds contribute to the secondary structure of proteins.
(2)
Answer: Hydrogen bonds form between the –NH and –CO groups in
the backbone; these stabilize structures such as alpha helices and beta
pleated sheets.
Q2
A student investigated enzyme activity at different temperatures.
Temperature (°C) Rate of reaction (arbitrary units)
10 5
20 12
30 20
40 25
50 10
(a) Describe the trend shown in the table. (2)
Answer: Rate increases with temperature up to 40°C, then decreases
sharply at 50°C.
(b) Explain the decrease in rate at 50°C. (2)
Answer: Enzyme denatures; active site changes shape; substrate no
longer fits.
Q3
, (a) Describe two differences between prokaryotic and eukaryotic cells. (2)
Answer: Prokaryotes lack membrane-bound organelles; DNA is
circular and not in a nucleus.
(b) Name one organelle involved in protein synthesis. (1)
Answer: Ribosome.
Q4
(a) State the function of cholesterol in cell membranes. (1)
Answer: Maintains membrane fluidity/stability.
(b) Explain how facilitated diffusion differs from active transport. (2)
Answer: Facilitated diffusion is passive and down a concentration
gradient; active transport requires ATP and moves substances against
a gradient.
Q5
(a) Define diffusion. (1)
Answer: Net movement of particles from high to low concentration.
(b) Suggest two adaptations of alveoli for efficient gas exchange. (2)
Answer: Large surface area; thin walls (short diffusion distance).
Q6
(a) State the role of ATP in cells. (1)
Answer: Immediate energy source for cellular processes.
