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A-Level Biology (9700) Paper 4 Mock: DNA, Proteins, Genetics, Respiration, Photosynthesis, Immunity
TUTORZONE ORIGINAL MOCK PAPER · CAMBRIDGE A LEVEL BIOLOGY (9700) PAPER 4 (A2 STRUCTURED)
Written to the Cambridge 9700 syllabus (2025-2027): Paper 4 (A Level structured) is 100 marks over 2 hours, 38.5% of the A Level. This is a Paper 4 mock: 10 questions for 100 marks (calculation and concept) with answers.
What is in the A-Level Biology (9700) exam?
Direct answer: A Level candidates sit five papers: Paper 1 (MC 40), Paper 2 (AS structured 60, 1 h 15), Paper 3 (practical 40, 2 h), Paper 4 (A2 structured 100, 2 h) and Paper 5 (planning 30, 1 h 15).
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Paper 4 (A Level structured) | Structured questions, 100 marks | 100 (38.5% A Level) | 2 h |
| Paper 5 (Planning, Analysis and Evaluation) | Two compulsory questions, 30 marks | 30 (11.5% A Level) | 1 h 15 min |
| Paper 1/2/3 (AS level) | MC 40 + structured 60 + practical 40 | 140 (AS) | 1h15 / 1h15 / 2h |
Ten questions in 2 hours is about 11 minutes each. For concepts give the definition and an example (DNA, immunity, natural selection); for calculations show the steps (genetic ratio, Hardy-Weinberg).
How this paper was built
This is a TutorZone original mock paper: the questions follow the Cambridge 9700 structure (Paper 4 A2 structured, 100 marks, 2 h) and the answers are our own, not Cambridge past papers or marking references.
The numerical answer (Hardy-Weinberg) was recomputed programmatically.
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Paper 4 (A Level structured) | 100 (38.5% A Level) | about 11 min per question, 10 to check | definition for concepts, steps for calculations |
| Paper 5 (Planning, Analysis and Evaluation) | 30 (11.5% A Level) | about 35 min per question | design, analyse, evaluate |
| Paper 1/2/3 (AS level) | 140 (AS) | AS underpins A2 | A2 builds on AS content |
What is the DNA base pairing?
Direct answer: A-T and C-G (adenine with thymine, cytosine with guanine).
Paper 4: structured questions (10 questions, 100 marks)
All compulsory; aim for 110 minutes with 10 to check. Definition for concepts, steps for calculations.
Question 1 (10 marks)
Describe the structure of a DNA molecule, and state the complementary base pairing.
Question 2 (10 marks)
Outline the two steps of protein synthesis: transcription and translation.
Question 3 (10 marks)
Two heterozygotes (Aa x Aa) mate, A dominant to a. State the phenotypic ratio (dominant : recessive).
Question 4 (10 marks)
Write the equation for aerobic respiration and state where it occurs.
Question 5 (10 marks)
Write the equation for photosynthesis and state where the light-dependent and light-independent reactions occur.
Question 6 (10 marks)
Explain the role of antibodies in the immune response.
Question 7 (10 marks)
Compare diffusion, osmosis and active transport across a membrane.
Question 8 (10 marks)
Explain how natural selection leads to evolution.
Question 9 (10 marks)
In a Hardy-Weinberg population, the recessive phenotype is 16%. Calculate the recessive allele frequency q and the heterozygote frequency.
Question 10 (10 marks)
Explain why energy decreases at each trophic level of a food chain.
Where do the two photosynthesis stages occur?
Direct answer: the light-dependent reaction in the thylakoids and the light-independent in the stroma (both in the chloroplast).
Paper 4 answers
Question 1
DNA is a double helix, two polynucleotide strands held by hydrogen bonds between bases (5); complementary pairing: A-T and C-G (5).
Question 2
(1) Transcription: the gene sequence is transcribed into mRNA (in the nucleus) (5). (2) Translation: ribosomes read the mRNA codons and tRNA brings amino acids to build the polypeptide (5).
Question 3
Genotypes AA : Aa : aa = 1 : 2 : 1 (5); the phenotype ratio dominant : recessive is 3 : 1 (5).
Question 4
glucose + oxygen -> carbon dioxide + water (+ energy) (6); it occurs mainly in the mitochondria (4).
Question 5
carbon dioxide + water -> (light, chlorophyll) glucose + oxygen (4); the light-dependent reaction is in the thylakoids and the light-independent in the stroma (3 each).
Question 6
Antibodies are produced by plasma cells (from B cells) and bind specifically to antigens (5); they mark pathogens for phagocytosis or neutralise toxins (5).
Question 7
(1) Diffusion: particles high to low concentration, no energy (4). (2) Osmosis: water through a partially permeable membrane high to low water potential, no energy (3). (3) Active transport: against the gradient, needs energy (ATP) and carrier proteins (3).
Question 8
A population varies; under changed conditions the better-adapted survive and reproduce; the favourable traits are inherited and accumulate into evolution (10).
Question 9
q^2 = 0.16, so q = sqrt(0.16) = 0.4 (5); heterozygote = 2pq = 2 x 0.6 x 0.4 = 0.48 (48%) (5).
Question 10
Energy is used at each level for respiration, movement and maintenance and lost as heat (5); only a small part becomes biomass passed up, so it decreases each level (5).
What is Hardy-Weinberg equilibrium?
Direct answer: p^2 + 2pq + q^2 = 1, describing allele and genotype frequencies without evolutionary forces.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Wrong base pairing | A-C and G-T | DNA pairs are A-T and C-G | Write A-T and C-G |
| Hardy-Weinberg error | Treating q^2 as q | The recessive phenotype is q^2, take the square root | q = sqrt(q^2) |
| Photosynthesis location | Dark reaction in the thylakoid | Light = thylakoid, dark = stroma | Light in thylakoid, dark in stroma |
How to use this paper
First sit: the full 2 hours on all 10 questions with no references.
Mark it: check definitions and calculation steps.
Second sit: redo three to seven days later, aiming to finish inside 1 h 45 min.
What should I do after finishing this paper?
Direct answer: log questions with missing concepts or wrong steps; redo in three to seven days; and drill Paper 5 planning questions.
FAQ
Is this a Cambridge paper?
No. The questions and answers are TutorZone originals, not Cambridge past papers or marking references.
How many papers does A-Level Biology have?
A Level candidates sit five: Paper 1 (MC 40), Paper 2 (AS structured 60), Paper 3 (practical 40), Paper 4 (A2 structured 100) and Paper 5 (planning 30).
How is Hardy-Weinberg calculated?
p^2 + 2pq + q^2 = 1; the recessive phenotype is q^2, so take the square root first.
Official references
| Resource | What to check |
|---|---|
| Cambridge A Level Biology 9700 syllabus (2025-2027) | Confirm the Paper 1-5 marks and times |
| https://www.tutorzone.com.hk/en-igcse-biology-0610-paper-4-mock-2027/ | IGCSE Biology (0610) Paper 4 mock |
Related: A-Level Biology 9700 drill guide · practice area · A-Level Chemistry Paper 4 mock
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