AQA AS Biology 7401/2 Paper 2 Mark Scheme June
2026/2027 – Complete Marking Scheme with Detailed
Rationales | 100% Verified | Pass Guaranteed – A+ Graded
Section A: Biological Molecules & Cell Structure (Questions 1–15)
Q1: A student performs the Benedict's test on three solutions: glucose, sucrose, and
starch. After heating, which result is consistent with AQA required practical protocols?
A. Glucose: blue; Sucrose: brick red; Starch: green
B. Glucose: brick red precipitate; Sucrose: remains blue; Starch: remains blue
[CORRECT]
C. Glucose: blue; Sucrose: brick red; Starch: brick red
D. Glucose: green; Sucrose: yellow; Starch: brick red
Correct Answer: B
Rationale: Benedict's test detects reducing sugars. Glucose (reducing sugar) produces a
brick red precipitate when heated. Sucrose (non-reducing sugar) and starch
(polysaccharide, non-reducing) both remain blue as they do not reduce Benedict's
reagent without prior acid hydrolysis. AO1: Knowledge of biochemical test outcomes;
AO2: Application to specific sugar types.
Q2: In the biuret test for protein, the colour change observed is:
A. Blue to brick red
B. Blue to black
C. Blue to purple [CORRECT]
D. Colourless to orange
Correct Answer: C
Rationale: The biuret test detects peptide bonds. In alkaline conditions, copper(II) ions
form a complex with peptide bonds, producing a purple/mauve colour. Blue to brick red
is Benedict's; blue to black is iodine test for starch; colourless to orange is not a
standard AQA biochemical test result. AO1: Recall of test procedures and outcomes.
Q3: A lipid sample is tested using the emulsion test. The expected positive result is:
,A. A red precipitate
B. A cloudy white emulsion [CORRECT]
C. A blue-black colour
D. A purple colour
Correct Answer: B
Rationale: The emulsion test for lipids involves shaking the sample with ethanol and
then adding water. A positive result is a cloudy white emulsion as the lipid forms tiny
droplets in the water. Red precipitate is Benedict's; blue-black is iodine-starch; purple is
biuret. AO1: Recall of lipid test procedure and outcome.
Q4: Which of the following correctly describes the structural relationship between
monomers and polymers in carbohydrates?
A. Monosaccharides are polymers formed from condensation of disaccharides
B. Polysaccharides are polymers formed from condensation of monosaccharides
[CORRECT]
C. Disaccharides are monomers that cannot form polymers
D. Monosaccharides are formed by hydrolysis of polysaccharides only
Correct Answer: B
Rationale: Polysaccharides (starch, glycogen, cellulose) are polymers formed by
condensation reactions between monosaccharide monomers, releasing water.
Monosaccharides are monomers, not polymers. Disaccharides are dimers, not
monomers. Hydrolysis breaks polymers into monomers; the reverse statement is
incorrect. AO1: Knowledge of polymer chemistry in biological molecules.
Q5: A student observes a cell under an electron microscope and notes the presence of a
nucleus, mitochondria, ribosomes, and a cell wall. The cell is most likely:
A. A prokaryotic bacterium
B. A eukaryotic plant cell [CORRECT]
C. A eukaryotic animal cell
D. A virus
Correct Answer: B
Rationale: The presence of a nucleus and membrane-bound organelles (mitochondria)
indicates a eukaryote. The presence of a cell wall indicates a plant cell (or fungus,
though fungi lack chloroplasts). Animal cells lack cell walls; prokaryotes lack nuclei and
,mitochondria; viruses are not cells. AO2: Application of cell structure knowledge to
identify cell type.
Q6: The rough endoplasmic reticulum (RER) is described as "rough" because:
A. It has a folded membrane increasing surface area
B. It is studded with ribosomes [CORRECT]
C. It contains digestive enzymes
D. It is continuous with the nuclear envelope
Correct Answer: B
Rationale: The RER appears rough under electron microscopy due to ribosomes
attached to its cytosolic surface. These ribosomes synthesise proteins that enter the
RER lumen for processing and transport. Folded membrane describes cristae
(mitochondria) or thylakoids (chloroplasts); digestive enzymes describe lysosomes;
nuclear envelope continuity is true but not the reason for the "rough" description. AO1:
Recall of organelle structure and function.
Q7: Which organelle is responsible for producing ATP through aerobic respiration?
A. Ribosome
B. Golgi apparatus
C. Mitochondrion [CORRECT]
D. Lysosome
Correct Answer: C
Rationale: Mitochondria are the site of aerobic respiration, including the Krebs cycle and
oxidative phosphorylation, which produce ATP. Ribosomes synthesise proteins; Golgi
apparatus modifies and packages proteins; lysosomes contain hydrolytic enzymes for
intracellular digestion. AO1: Knowledge of organelle function.
Q8: A student prepares a slide of onion epidermis and adds iodine solution. The cell
walls stain yellow-brown, but the cytoplasm contains dark blue-black granules. These
granules are:
A. Glycogen
B. Starch [CORRECT]
C. Lipid droplets
D. Protein bodies
Correct Answer: B
, Rationale: Iodine solution (iodine in potassium iodide) stains starch blue-black. Onion
cells store starch in amyloplasts. Glycogen does not stain with iodine (or stains
reddish-brown in animal tissues); lipids are detected by emulsion test; proteins by biuret
test. AO2: Application of biochemical test knowledge to cell structure observation.
Q9: In a prokaryotic cell, DNA is found:
A. Within a membrane-bound nucleus
B. In a single circular chromosome in the cytoplasm and possibly in plasmids
[CORRECT]
C. Only in mitochondria
D. Associated with histone proteins in chromatin
Correct Answer: B
Rationale: Prokaryotes lack a membrane-bound nucleus. Their genetic material consists
of a single circular chromosome in the nucleoid region and possibly small circular
plasmids. Mitochondria and histone-associated chromatin are eukaryotic features. AO1:
Recall of prokaryotic cell structure.
Q10: Which of the following is a structural difference between DNA and RNA?
A. DNA contains uracil; RNA contains thymine
B. DNA is double-stranded; RNA is typically single-stranded [CORRECT]
C. DNA contains ribose; RNA contains deoxyribose
D. DNA has a phosphate group; RNA does not
Correct Answer: B
Rationale: DNA is double-stranded with deoxyribose and thymine; RNA is typically
single-stranded with ribose and uracil. Option A reverses the bases; Option C reverses
the sugars; both DNA and RNA contain phosphate groups in their nucleotide structure.
AO1: Knowledge of nucleic acid structure.
Q11: A phospholipid bilayer forms the basis of cell membranes because phospholipids:
A. Are entirely hydrophilic
B. Have hydrophilic heads and hydrophobic tails, allowing spontaneous bilayer
formation in aqueous environments [CORRECT]
C. Are entirely hydrophobic
D. Form covalent bonds with water molecules
Correct Answer: B
2026/2027 – Complete Marking Scheme with Detailed
Rationales | 100% Verified | Pass Guaranteed – A+ Graded
Section A: Biological Molecules & Cell Structure (Questions 1–15)
Q1: A student performs the Benedict's test on three solutions: glucose, sucrose, and
starch. After heating, which result is consistent with AQA required practical protocols?
A. Glucose: blue; Sucrose: brick red; Starch: green
B. Glucose: brick red precipitate; Sucrose: remains blue; Starch: remains blue
[CORRECT]
C. Glucose: blue; Sucrose: brick red; Starch: brick red
D. Glucose: green; Sucrose: yellow; Starch: brick red
Correct Answer: B
Rationale: Benedict's test detects reducing sugars. Glucose (reducing sugar) produces a
brick red precipitate when heated. Sucrose (non-reducing sugar) and starch
(polysaccharide, non-reducing) both remain blue as they do not reduce Benedict's
reagent without prior acid hydrolysis. AO1: Knowledge of biochemical test outcomes;
AO2: Application to specific sugar types.
Q2: In the biuret test for protein, the colour change observed is:
A. Blue to brick red
B. Blue to black
C. Blue to purple [CORRECT]
D. Colourless to orange
Correct Answer: C
Rationale: The biuret test detects peptide bonds. In alkaline conditions, copper(II) ions
form a complex with peptide bonds, producing a purple/mauve colour. Blue to brick red
is Benedict's; blue to black is iodine test for starch; colourless to orange is not a
standard AQA biochemical test result. AO1: Recall of test procedures and outcomes.
Q3: A lipid sample is tested using the emulsion test. The expected positive result is:
,A. A red precipitate
B. A cloudy white emulsion [CORRECT]
C. A blue-black colour
D. A purple colour
Correct Answer: B
Rationale: The emulsion test for lipids involves shaking the sample with ethanol and
then adding water. A positive result is a cloudy white emulsion as the lipid forms tiny
droplets in the water. Red precipitate is Benedict's; blue-black is iodine-starch; purple is
biuret. AO1: Recall of lipid test procedure and outcome.
Q4: Which of the following correctly describes the structural relationship between
monomers and polymers in carbohydrates?
A. Monosaccharides are polymers formed from condensation of disaccharides
B. Polysaccharides are polymers formed from condensation of monosaccharides
[CORRECT]
C. Disaccharides are monomers that cannot form polymers
D. Monosaccharides are formed by hydrolysis of polysaccharides only
Correct Answer: B
Rationale: Polysaccharides (starch, glycogen, cellulose) are polymers formed by
condensation reactions between monosaccharide monomers, releasing water.
Monosaccharides are monomers, not polymers. Disaccharides are dimers, not
monomers. Hydrolysis breaks polymers into monomers; the reverse statement is
incorrect. AO1: Knowledge of polymer chemistry in biological molecules.
Q5: A student observes a cell under an electron microscope and notes the presence of a
nucleus, mitochondria, ribosomes, and a cell wall. The cell is most likely:
A. A prokaryotic bacterium
B. A eukaryotic plant cell [CORRECT]
C. A eukaryotic animal cell
D. A virus
Correct Answer: B
Rationale: The presence of a nucleus and membrane-bound organelles (mitochondria)
indicates a eukaryote. The presence of a cell wall indicates a plant cell (or fungus,
though fungi lack chloroplasts). Animal cells lack cell walls; prokaryotes lack nuclei and
,mitochondria; viruses are not cells. AO2: Application of cell structure knowledge to
identify cell type.
Q6: The rough endoplasmic reticulum (RER) is described as "rough" because:
A. It has a folded membrane increasing surface area
B. It is studded with ribosomes [CORRECT]
C. It contains digestive enzymes
D. It is continuous with the nuclear envelope
Correct Answer: B
Rationale: The RER appears rough under electron microscopy due to ribosomes
attached to its cytosolic surface. These ribosomes synthesise proteins that enter the
RER lumen for processing and transport. Folded membrane describes cristae
(mitochondria) or thylakoids (chloroplasts); digestive enzymes describe lysosomes;
nuclear envelope continuity is true but not the reason for the "rough" description. AO1:
Recall of organelle structure and function.
Q7: Which organelle is responsible for producing ATP through aerobic respiration?
A. Ribosome
B. Golgi apparatus
C. Mitochondrion [CORRECT]
D. Lysosome
Correct Answer: C
Rationale: Mitochondria are the site of aerobic respiration, including the Krebs cycle and
oxidative phosphorylation, which produce ATP. Ribosomes synthesise proteins; Golgi
apparatus modifies and packages proteins; lysosomes contain hydrolytic enzymes for
intracellular digestion. AO1: Knowledge of organelle function.
Q8: A student prepares a slide of onion epidermis and adds iodine solution. The cell
walls stain yellow-brown, but the cytoplasm contains dark blue-black granules. These
granules are:
A. Glycogen
B. Starch [CORRECT]
C. Lipid droplets
D. Protein bodies
Correct Answer: B
, Rationale: Iodine solution (iodine in potassium iodide) stains starch blue-black. Onion
cells store starch in amyloplasts. Glycogen does not stain with iodine (or stains
reddish-brown in animal tissues); lipids are detected by emulsion test; proteins by biuret
test. AO2: Application of biochemical test knowledge to cell structure observation.
Q9: In a prokaryotic cell, DNA is found:
A. Within a membrane-bound nucleus
B. In a single circular chromosome in the cytoplasm and possibly in plasmids
[CORRECT]
C. Only in mitochondria
D. Associated with histone proteins in chromatin
Correct Answer: B
Rationale: Prokaryotes lack a membrane-bound nucleus. Their genetic material consists
of a single circular chromosome in the nucleoid region and possibly small circular
plasmids. Mitochondria and histone-associated chromatin are eukaryotic features. AO1:
Recall of prokaryotic cell structure.
Q10: Which of the following is a structural difference between DNA and RNA?
A. DNA contains uracil; RNA contains thymine
B. DNA is double-stranded; RNA is typically single-stranded [CORRECT]
C. DNA contains ribose; RNA contains deoxyribose
D. DNA has a phosphate group; RNA does not
Correct Answer: B
Rationale: DNA is double-stranded with deoxyribose and thymine; RNA is typically
single-stranded with ribose and uracil. Option A reverses the bases; Option C reverses
the sugars; both DNA and RNA contain phosphate groups in their nucleotide structure.
AO1: Knowledge of nucleic acid structure.
Q11: A phospholipid bilayer forms the basis of cell membranes because phospholipids:
A. Are entirely hydrophilic
B. Have hydrophilic heads and hydrophobic tails, allowing spontaneous bilayer
formation in aqueous environments [CORRECT]
C. Are entirely hydrophobic
D. Form covalent bonds with water molecules
Correct Answer: B
