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AQA A-LEVEL BIOLOGY PAPER 1 2026/2027 |
BIOLOGY | 100 VERIFIED Q&A | DETAILED
RATIONALES | PASS GUARANTEED – A+ GRADED
SECTION 1: BIOLOGICAL MOLECULES - Questions 1-25
Q1: Water as a Solvent
The student is reviewing biological molecules. Why is water an excellent solvent for biological
reactions?
A. It is a non-polar molecule
B. It is a polar molecule with hydrogen bonds
C. It has a low specific heat capacity
D. It is less dense as a solid
Correct Answer: B
Rationale: Water is polar, with partial positive and negative charges. This allows it to surround ions
and polar molecules, dissolving them and enabling reactions. Non-polar substances do not dissolve.
Low specific heat and ice density are unrelated to solvent properties. [100% CORRECT]
Q2: Condensation Reaction
The student is reviewing carbohydrates. What type of reaction joins two monosaccharides to form a
disaccharide?
A. Hydrolysis
B. Condensation
C. Oxidation
D. Reduction
Correct Answer: B
Rationale: A condensation reaction joins two monosaccharides, forming a glycosidic bond and
releasing a water molecule. Hydrolysis breaks the bond using water. [100% CORRECT]
Q3: Starch Structure
The student is reviewing polysaccharides. Which statement about starch is correct?
A. It is a branched polymer of β-glucose
B. It is a mixture of amylose and amylopectin
C. It is found in animal cells
D. It is a structural polysaccharide
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Correct Answer: B
Rationale: Starch is a mixture of amylose (unbranched) and amylopectin (branched), both polymers
of α-glucose. It is a storage polysaccharide in plants. Glycogen is the animal storage polysaccharide.
Cellulose is structural. [100% CORRECT]
Q4: Triglyceride Formation
The student is reviewing lipids. A triglyceride is formed by the condensation of:
A. One glycerol and three fatty acids
B. One glycerol and two fatty acids
C. Three glycerols and one fatty acid
D. Two glycerols and three fatty acids
Correct Answer: A
Rationale: Triglycerides consist of one glycerol molecule ester-bonded to three fatty acids. Each
ester bond forms via condensation, releasing water. [100% CORRECT]
Q5: Saturated vs Unsaturated Fatty Acids
The student is reviewing lipids. What is the difference between saturated and unsaturated fatty
acids?
A. Saturated have C=C double bonds; unsaturated do not
B. Unsaturated have C=C double bonds; saturated do not
C. Saturated are liquid at room temperature
D. Unsaturated are solid at room temperature
Correct Answer: B
Rationale: Unsaturated fatty acids contain one or more carbon-carbon double bonds, causing kinks
that prevent tight packing and lower melting point. Saturated fatty acids have no C=C bonds. [100%
CORRECT]
Q6: Amino Acid Structure
The student is reviewing proteins. Which group is found in all amino acids?
A. Carboxyl group, amino group, hydrogen, R group
B. Hydroxyl group, amino group, R group
C. Carboxyl group, phosphate group, R group
D. Amino group, sulfate group, R group
Correct Answer: A
Rationale: All amino acids have a central carbon bonded to an amino group (-NH₂), a carboxyl group
(-COOH), a hydrogen atom, and a variable R group. [100% CORRECT]
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Q7: Peptide Bond Formation
The student is reviewing proteins. A peptide bond forms between:
A. Two carboxyl groups
B. Two amino groups
C. The carboxyl group of one amino acid and the amino group of another
D. The R groups of two amino acids
Correct Answer: C
Rationale: A peptide bond is a covalent bond formed by condensation between the carboxyl group
of one amino acid and the amino group of another, releasing water. [100% CORRECT]
Q8: Protein Structure Levels
The student is reviewing protein structure. Which level of protein structure is determined by the
sequence of amino acids?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Correct Answer: A
Rationale: Primary structure is the specific sequence of amino acids in a polypeptide chain,
determined by DNA. Secondary structure refers to α-helices and β-pleated sheets. Tertiary is 3D
folding. Quaternary involves multiple polypeptides. [100% CORRECT]
Q9: Enzyme Specificity
The student is reviewing enzymes. Enzymes are specific because:
A. They have a complementary active site to the substrate
B. They are proteins
C. They lower activation energy
D. They are affected by pH
Correct Answer: A
Rationale: The active site has a specific shape and chemistry complementary to the substrate,
forming an enzyme-substrate complex. This specificity is explained by the induced-fit model. [100%
CORRECT]
Q10: Enzyme Denaturation
The student is reviewing enzymes. What happens when an enzyme is denatured?
A. The active site changes shape, so substrates cannot bind
B. The enzyme is broken down into amino acids
AQA A-LEVEL BIOLOGY PAPER 1 2026/2027 |
BIOLOGY | 100 VERIFIED Q&A | DETAILED
RATIONALES | PASS GUARANTEED – A+ GRADED
SECTION 1: BIOLOGICAL MOLECULES - Questions 1-25
Q1: Water as a Solvent
The student is reviewing biological molecules. Why is water an excellent solvent for biological
reactions?
A. It is a non-polar molecule
B. It is a polar molecule with hydrogen bonds
C. It has a low specific heat capacity
D. It is less dense as a solid
Correct Answer: B
Rationale: Water is polar, with partial positive and negative charges. This allows it to surround ions
and polar molecules, dissolving them and enabling reactions. Non-polar substances do not dissolve.
Low specific heat and ice density are unrelated to solvent properties. [100% CORRECT]
Q2: Condensation Reaction
The student is reviewing carbohydrates. What type of reaction joins two monosaccharides to form a
disaccharide?
A. Hydrolysis
B. Condensation
C. Oxidation
D. Reduction
Correct Answer: B
Rationale: A condensation reaction joins two monosaccharides, forming a glycosidic bond and
releasing a water molecule. Hydrolysis breaks the bond using water. [100% CORRECT]
Q3: Starch Structure
The student is reviewing polysaccharides. Which statement about starch is correct?
A. It is a branched polymer of β-glucose
B. It is a mixture of amylose and amylopectin
C. It is found in animal cells
D. It is a structural polysaccharide
,2
Correct Answer: B
Rationale: Starch is a mixture of amylose (unbranched) and amylopectin (branched), both polymers
of α-glucose. It is a storage polysaccharide in plants. Glycogen is the animal storage polysaccharide.
Cellulose is structural. [100% CORRECT]
Q4: Triglyceride Formation
The student is reviewing lipids. A triglyceride is formed by the condensation of:
A. One glycerol and three fatty acids
B. One glycerol and two fatty acids
C. Three glycerols and one fatty acid
D. Two glycerols and three fatty acids
Correct Answer: A
Rationale: Triglycerides consist of one glycerol molecule ester-bonded to three fatty acids. Each
ester bond forms via condensation, releasing water. [100% CORRECT]
Q5: Saturated vs Unsaturated Fatty Acids
The student is reviewing lipids. What is the difference between saturated and unsaturated fatty
acids?
A. Saturated have C=C double bonds; unsaturated do not
B. Unsaturated have C=C double bonds; saturated do not
C. Saturated are liquid at room temperature
D. Unsaturated are solid at room temperature
Correct Answer: B
Rationale: Unsaturated fatty acids contain one or more carbon-carbon double bonds, causing kinks
that prevent tight packing and lower melting point. Saturated fatty acids have no C=C bonds. [100%
CORRECT]
Q6: Amino Acid Structure
The student is reviewing proteins. Which group is found in all amino acids?
A. Carboxyl group, amino group, hydrogen, R group
B. Hydroxyl group, amino group, R group
C. Carboxyl group, phosphate group, R group
D. Amino group, sulfate group, R group
Correct Answer: A
Rationale: All amino acids have a central carbon bonded to an amino group (-NH₂), a carboxyl group
(-COOH), a hydrogen atom, and a variable R group. [100% CORRECT]
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Q7: Peptide Bond Formation
The student is reviewing proteins. A peptide bond forms between:
A. Two carboxyl groups
B. Two amino groups
C. The carboxyl group of one amino acid and the amino group of another
D. The R groups of two amino acids
Correct Answer: C
Rationale: A peptide bond is a covalent bond formed by condensation between the carboxyl group
of one amino acid and the amino group of another, releasing water. [100% CORRECT]
Q8: Protein Structure Levels
The student is reviewing protein structure. Which level of protein structure is determined by the
sequence of amino acids?
A. Primary
B. Secondary
C. Tertiary
D. Quaternary
Correct Answer: A
Rationale: Primary structure is the specific sequence of amino acids in a polypeptide chain,
determined by DNA. Secondary structure refers to α-helices and β-pleated sheets. Tertiary is 3D
folding. Quaternary involves multiple polypeptides. [100% CORRECT]
Q9: Enzyme Specificity
The student is reviewing enzymes. Enzymes are specific because:
A. They have a complementary active site to the substrate
B. They are proteins
C. They lower activation energy
D. They are affected by pH
Correct Answer: A
Rationale: The active site has a specific shape and chemistry complementary to the substrate,
forming an enzyme-substrate complex. This specificity is explained by the induced-fit model. [100%
CORRECT]
Q10: Enzyme Denaturation
The student is reviewing enzymes. What happens when an enzyme is denatured?
A. The active site changes shape, so substrates cannot bind
B. The enzyme is broken down into amino acids
