AQA A LEVEL BIOLOGY EXAM – COMPREHENSIVE
QUESTIONS AND ANSWERS | VERIFIED AND
WELL-DETAILED ANSWERS | DETAILED
EXPLANATIONS AND RATIONALES | COMPLETE
EXAM PREPARATION STUDY GUIDE | PRACTICE
QUESTIONS | LATEST EXAM UPDATE
CORE DOMAINS
1. Biological molecules
2. Cells and cellular processes
3. Exchange of substances and transport
4. Genetic information, variation and evolution
5. Energy transfers in organisms
6. Organisms responding to internal and external changes
7. Genetics, populations, evolution and ecosystems
8. Control of gene expression
9. Practical, mathematical and data-analysis skills
INTRODUCTION
This assessment provides comprehensive AQA A-level Biology 7402 practice across the
major areas of the specification. The questions assess knowledge and understanding
alongside application, interpretation, calculation, experimental design and biological
reasoning. AQA examinations require students to apply biological principles in theoretical
and practical contexts, analyse quantitative and qualitative information, and evaluate
evidence. The questions therefore include both foundational and higher-order problems
designed to strengthen examination technique. Particular attention is given to mechanisms,
relationships between biological processes, experimental variables, calculations, data
interpretation and common conceptual distinctions. The material is intended as an original
study and revision resource rather than a reproduction of confidential or unreleased
examination questions.
SECTION ONE: QUESTIONS 1–100
,Question 1. Which bond is formed between two amino acids during condensation?
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Phosphodiester bond
Correct Answer: B. Peptide bond
Explanation: A peptide bond forms between the carboxyl group of one amino acid and the
amino group of another during a condensation reaction. Water is released. Glycosidic bonds
join monosaccharides, whereas phosphodiester bonds occur in nucleic acids.
Question 2. Which property of water is particularly important for transporting substances in
organisms?
A. Its ability to form ionic bonds with all solutes
B. Its high specific latent heat
C. Its polarity and ability to dissolve many substances
D. Its inability to interact with non-polar molecules
Correct Answer: C. Its polarity and ability to dissolve many substances
Explanation: Water is polar because of unequal electron distribution within its molecule.
This allows it to interact with ions and polar molecules, making it an effective solvent for
many substances transported in blood, tissue fluid and plant transport systems.
Question 3. Which reagent is used to test for reducing sugars?
A. Biuret reagent
B. Benedict's reagent
C. Iodine solution
D. Sudan III
Correct Answer: B. Benedict's reagent
Explanation: Benedict's reagent is used to test for reducing sugars. When heated with a
reducing sugar, the solution can change from blue through green, yellow and orange to a
brick-red precipitate depending on concentration. Biuret tests proteins, iodine tests starch
and Sudan III tests lipids.
Question 4. What is the main role of cellulose in plant cells?
A. Energy storage
B. Formation of enzymes
C. Structural support in cell walls
D. Storage of genetic information
, Correct Answer: C. Structural support in cell walls
Explanation: Cellulose consists of long chains of β-glucose joined by β-1,4 glycosidic bonds.
Hydrogen bonding between chains produces microfibrils that provide strength to plant cell
walls.
Question 5. Which feature distinguishes triglycerides from phospholipids?
A. Triglycerides contain glycerol
B. Phospholipids contain fatty acids
C. Triglycerides have three fatty acids attached to glycerol
D. Phospholipids cannot contain phosphorus
Correct Answer: C. Triglycerides have three fatty acids attached to glycerol
Explanation: A triglyceride consists of glycerol esterified with three fatty acids. A
phospholipid contains glycerol, two fatty acids and a phosphate-containing group. The
arrangement gives phospholipids their hydrophilic heads and hydrophobic tails.
Question 6. Why does increasing temperature initially increase the rate of an enzyme-
controlled reaction?
A. More enzyme molecules are produced
B. Substrate molecules become enzymes
C. Molecules have greater kinetic energy and collide more frequently
D. The active site permanently changes shape
Correct Answer: C. Molecules have greater kinetic energy and collide more frequently
Explanation: Increasing temperature increases kinetic energy, causing more frequent
successful collisions between enzyme and substrate. Above the enzyme's optimum
temperature, disruption of bonds maintaining tertiary structure can alter the active site and
reduce activity.
Question 7. An enzyme has a much lower activity at pH 3 than at pH 7. What is the most
likely explanation?
A. The enzyme has been converted into glucose
B. Hydrogen ion concentration affects bonds maintaining the enzyme's structure
C. Substrate concentration always decreases at low pH
D. ATP cannot exist below pH 7
Correct Answer: B. Hydrogen ion concentration affects bonds maintaining the enzyme's
structure
Explanation: Changes in pH alter hydrogen ion concentration and can disrupt ionic and
hydrogen bonds involved in maintaining protein structure. This can alter the tertiary
structure and active site, reducing enzyme activity.
QUESTIONS AND ANSWERS | VERIFIED AND
WELL-DETAILED ANSWERS | DETAILED
EXPLANATIONS AND RATIONALES | COMPLETE
EXAM PREPARATION STUDY GUIDE | PRACTICE
QUESTIONS | LATEST EXAM UPDATE
CORE DOMAINS
1. Biological molecules
2. Cells and cellular processes
3. Exchange of substances and transport
4. Genetic information, variation and evolution
5. Energy transfers in organisms
6. Organisms responding to internal and external changes
7. Genetics, populations, evolution and ecosystems
8. Control of gene expression
9. Practical, mathematical and data-analysis skills
INTRODUCTION
This assessment provides comprehensive AQA A-level Biology 7402 practice across the
major areas of the specification. The questions assess knowledge and understanding
alongside application, interpretation, calculation, experimental design and biological
reasoning. AQA examinations require students to apply biological principles in theoretical
and practical contexts, analyse quantitative and qualitative information, and evaluate
evidence. The questions therefore include both foundational and higher-order problems
designed to strengthen examination technique. Particular attention is given to mechanisms,
relationships between biological processes, experimental variables, calculations, data
interpretation and common conceptual distinctions. The material is intended as an original
study and revision resource rather than a reproduction of confidential or unreleased
examination questions.
SECTION ONE: QUESTIONS 1–100
,Question 1. Which bond is formed between two amino acids during condensation?
A. Glycosidic bond
B. Peptide bond
C. Hydrogen bond
D. Phosphodiester bond
Correct Answer: B. Peptide bond
Explanation: A peptide bond forms between the carboxyl group of one amino acid and the
amino group of another during a condensation reaction. Water is released. Glycosidic bonds
join monosaccharides, whereas phosphodiester bonds occur in nucleic acids.
Question 2. Which property of water is particularly important for transporting substances in
organisms?
A. Its ability to form ionic bonds with all solutes
B. Its high specific latent heat
C. Its polarity and ability to dissolve many substances
D. Its inability to interact with non-polar molecules
Correct Answer: C. Its polarity and ability to dissolve many substances
Explanation: Water is polar because of unequal electron distribution within its molecule.
This allows it to interact with ions and polar molecules, making it an effective solvent for
many substances transported in blood, tissue fluid and plant transport systems.
Question 3. Which reagent is used to test for reducing sugars?
A. Biuret reagent
B. Benedict's reagent
C. Iodine solution
D. Sudan III
Correct Answer: B. Benedict's reagent
Explanation: Benedict's reagent is used to test for reducing sugars. When heated with a
reducing sugar, the solution can change from blue through green, yellow and orange to a
brick-red precipitate depending on concentration. Biuret tests proteins, iodine tests starch
and Sudan III tests lipids.
Question 4. What is the main role of cellulose in plant cells?
A. Energy storage
B. Formation of enzymes
C. Structural support in cell walls
D. Storage of genetic information
, Correct Answer: C. Structural support in cell walls
Explanation: Cellulose consists of long chains of β-glucose joined by β-1,4 glycosidic bonds.
Hydrogen bonding between chains produces microfibrils that provide strength to plant cell
walls.
Question 5. Which feature distinguishes triglycerides from phospholipids?
A. Triglycerides contain glycerol
B. Phospholipids contain fatty acids
C. Triglycerides have three fatty acids attached to glycerol
D. Phospholipids cannot contain phosphorus
Correct Answer: C. Triglycerides have three fatty acids attached to glycerol
Explanation: A triglyceride consists of glycerol esterified with three fatty acids. A
phospholipid contains glycerol, two fatty acids and a phosphate-containing group. The
arrangement gives phospholipids their hydrophilic heads and hydrophobic tails.
Question 6. Why does increasing temperature initially increase the rate of an enzyme-
controlled reaction?
A. More enzyme molecules are produced
B. Substrate molecules become enzymes
C. Molecules have greater kinetic energy and collide more frequently
D. The active site permanently changes shape
Correct Answer: C. Molecules have greater kinetic energy and collide more frequently
Explanation: Increasing temperature increases kinetic energy, causing more frequent
successful collisions between enzyme and substrate. Above the enzyme's optimum
temperature, disruption of bonds maintaining tertiary structure can alter the active site and
reduce activity.
Question 7. An enzyme has a much lower activity at pH 3 than at pH 7. What is the most
likely explanation?
A. The enzyme has been converted into glucose
B. Hydrogen ion concentration affects bonds maintaining the enzyme's structure
C. Substrate concentration always decreases at low pH
D. ATP cannot exist below pH 7
Correct Answer: B. Hydrogen ion concentration affects bonds maintaining the enzyme's
structure
Explanation: Changes in pH alter hydrogen ion concentration and can disrupt ionic and
hydrogen bonds involved in maintaining protein structure. This can alter the tertiary
structure and active site, reducing enzyme activity.
