AQA A-level BIOLOGY 7402/1 Paper 1 Mark Scheme
Specimen V1 Actual Exam 2026/2027 – Complete Q&A with
Detailed Rationales | 100% Verified | Pass Guaranteed – A+
Graded
Section A: Biological Molecules & Cell Structure
Q1: A student adds Benedict's reagent to a sample and heats it. The solution changes
from blue to brick-red. Which carbohydrate is present?
A. Sucrose only
B. A non-reducing disaccharide
C. A reducing sugar or a disaccharide that has been hydrolysed [CORRECT]
D. Starch
Correct Answer: C
Rationale: Benedict's test detects reducing sugars (glucose, fructose, maltose) by
reducing Cu²⁺ to Cu⁺, producing a brick-red precipitate. Non-reducing sugars like
sucrose (Option A) give a negative result unless hydrolysed first. Option B describes
sucrose before hydrolysis, which would remain blue. Option D requires iodine test, not
Benedict's.
Q2: Which of the following correctly describes the relationship between
monosaccharides and polysaccharides?
,A. Polysaccharides are broken down into monosaccharides by condensation reactions
B. Monosaccharides are joined by glycosidic bonds formed during condensation
reactions to produce polysaccharides [CORRECT]
C. Hydrolysis of starch produces amino acids
D. Cellulose is a disaccharide made from glucose and fructose
Correct Answer: B
Rationale: Monosaccharides join via condensation reactions, releasing water and
forming glycosidic bonds to produce polysaccharides. Option A reverses the reaction
type—hydrolysis breaks polysaccharides down. Option C is incorrect—starch hydrolysis
yields glucose, not amino acids. Option D is incorrect—cellulose is a polysaccharide of
β-glucose, not a disaccharide.
Q3: A phospholipid differs from a triglyceride in that:
A. A phospholipid contains three fatty acids and no phosphate group
B. A triglyceride contains a phosphate group and two fatty acids
C. A phospholipid contains two fatty acids and a phosphate group attached to glycerol
[CORRECT]
D. Both contain identical structures with only the fatty acid chain length differing
Correct Answer: C
Rationale: Phospholipids have glycerol with two fatty acids and a phosphate group
(forming the hydrophilic head), whereas triglycerides have three fatty acids. Options A
, and B reverse the structures. Option D is incorrect—the phosphate group is the defining
difference.
Q4: Which level of protein structure is primarily determined by hydrogen bonds between
the C=O and N-H groups of the polypeptide backbone?
A. Primary structure
B. Secondary structure [CORRECT]
C. Tertiary structure
D. Quaternary structure
Correct Answer: B
Rationale: Secondary structure (α-helices and β-pleated sheets) is stabilized by
hydrogen bonds between the peptide backbone groups. Primary structure (Option A) is
the amino acid sequence. Tertiary structure (Option C) involves R-group interactions.
Quaternary structure (Option D) involves multiple polypeptide subunits.
Q5: The biuret test for proteins requires:
A. Copper sulfate in alkaline conditions to detect peptide bonds [CORRECT]
B. Iodine solution to detect starch contamination
C. Ethanol to dissolve the protein
D. Acidic conditions to hydrolyse the protein first
Correct Answer: A
Specimen V1 Actual Exam 2026/2027 – Complete Q&A with
Detailed Rationales | 100% Verified | Pass Guaranteed – A+
Graded
Section A: Biological Molecules & Cell Structure
Q1: A student adds Benedict's reagent to a sample and heats it. The solution changes
from blue to brick-red. Which carbohydrate is present?
A. Sucrose only
B. A non-reducing disaccharide
C. A reducing sugar or a disaccharide that has been hydrolysed [CORRECT]
D. Starch
Correct Answer: C
Rationale: Benedict's test detects reducing sugars (glucose, fructose, maltose) by
reducing Cu²⁺ to Cu⁺, producing a brick-red precipitate. Non-reducing sugars like
sucrose (Option A) give a negative result unless hydrolysed first. Option B describes
sucrose before hydrolysis, which would remain blue. Option D requires iodine test, not
Benedict's.
Q2: Which of the following correctly describes the relationship between
monosaccharides and polysaccharides?
,A. Polysaccharides are broken down into monosaccharides by condensation reactions
B. Monosaccharides are joined by glycosidic bonds formed during condensation
reactions to produce polysaccharides [CORRECT]
C. Hydrolysis of starch produces amino acids
D. Cellulose is a disaccharide made from glucose and fructose
Correct Answer: B
Rationale: Monosaccharides join via condensation reactions, releasing water and
forming glycosidic bonds to produce polysaccharides. Option A reverses the reaction
type—hydrolysis breaks polysaccharides down. Option C is incorrect—starch hydrolysis
yields glucose, not amino acids. Option D is incorrect—cellulose is a polysaccharide of
β-glucose, not a disaccharide.
Q3: A phospholipid differs from a triglyceride in that:
A. A phospholipid contains three fatty acids and no phosphate group
B. A triglyceride contains a phosphate group and two fatty acids
C. A phospholipid contains two fatty acids and a phosphate group attached to glycerol
[CORRECT]
D. Both contain identical structures with only the fatty acid chain length differing
Correct Answer: C
Rationale: Phospholipids have glycerol with two fatty acids and a phosphate group
(forming the hydrophilic head), whereas triglycerides have three fatty acids. Options A
, and B reverse the structures. Option D is incorrect—the phosphate group is the defining
difference.
Q4: Which level of protein structure is primarily determined by hydrogen bonds between
the C=O and N-H groups of the polypeptide backbone?
A. Primary structure
B. Secondary structure [CORRECT]
C. Tertiary structure
D. Quaternary structure
Correct Answer: B
Rationale: Secondary structure (α-helices and β-pleated sheets) is stabilized by
hydrogen bonds between the peptide backbone groups. Primary structure (Option A) is
the amino acid sequence. Tertiary structure (Option C) involves R-group interactions.
Quaternary structure (Option D) involves multiple polypeptide subunits.
Q5: The biuret test for proteins requires:
A. Copper sulfate in alkaline conditions to detect peptide bonds [CORRECT]
B. Iodine solution to detect starch contamination
C. Ethanol to dissolve the protein
D. Acidic conditions to hydrolyse the protein first
Correct Answer: A
