Fall Semester 2025 | AQA A Level Biology Complete Exam Study Pack | 300+ Verified Practice Questions with Correct Answers & Detailed Rationales | Updated 2025/2026 Edition for Paper 1, Paper 2 & Paper 3 | Comprehensive Revision & Assessment Resource for A

Fall SemeSter 2025 | aQa a level Biology
Complete exam Study paCk | 300+ veriFied
praCtiCe QueStionS with CorreCt anSwerS &
detailed rationaleS | updated 2025/2026
edition For paper 1, paper 2 & paper 3 |
ComprehenSive reviSion & aSSeSSment reSourCe
For aQa Biology StudentS

QUESTION 1:
What is the primary function of enzymes in biological reactions?
A. To increase the temperature of reactions
B. To provide energy
C. To act as catalysts, speeding up reactions
D. To decrease pH levels
CORRECT ANSWER:C. To act as catalysts, speeding up reactions
RATIONALE: Enzymes are biological catalysts that lower the activation energy of
reactions, thereby increasing the rate at which they occur.


QUESTION 2:
What is the structural unit of carbohydrates?
A. Fatty acids
B. Monosaccharides
C. Amino acids
D. Nucleotides
CORRECT ANSWER:B. Monosaccharides
RATIONALE: Monosaccharides are the simplest form of carbohydrates and serve as the
building blocks for larger carbohydrate molecules.


QUESTION 3:
What is the primary role of the ribosome in a cell?
A. To produce ATP
B. To synthesize lipids
C. To synthesize proteins
D. To transport materials
CORRECT ANSWER:C. To synthesize proteins
RATIONALE: Ribosomes are the cellular structures where protein synthesis occurs,
translating mRNA into amino acid sequences.

,QUESTION 4:
What is the function of the plasma membrane?
A. To provide energy
B. To synthesize proteins
C. To regulate the entry and exit of substances
D. To store genetic information
CORRECT ANSWER:C. To regulate the entry and exit of substances
RATIONALE: The plasma membrane controls what enters and leaves the cell,
maintaining homeostasis and protecting cellular integrity.


QUESTION 5:
What type of bond holds the two strands of DNA together?
A. Ionic bonds
B. Hydrogen bonds
C. Covalent bonds
D. Metallic bonds
CORRECT ANSWER:B. Hydrogen bonds
RATIONALE: Hydrogen bonds form between complementary base pairs, holding the
two strands of the DNA double helix together.


QUESTION 6:
What is the primary role of the mitochondria?
A. Photosynthesis
B. ATP production through cellular respiration
C. Protein synthesis
D. DNA replication
CORRECT ANSWER:B. ATP production through cellular respiration
RATIONALE: Mitochondria are known as the powerhouse of the cell, where ATP is
produced through aerobic respiration.


QUESTION 7:
What is the main difference between prokaryotic and eukaryotic cells?
A. Eukaryotic cells have a cell wall
B. Eukaryotic cells have a nucleus
C. Prokaryotic cells have ribosomes
D. Prokaryotic cells are larger

,CORRECT ANSWER:B. Eukaryotic cells have a nucleus
RATIONALE: Eukaryotic cells contain a membrane-bound nucleus, while prokaryotic
cells do not.


QUESTION 8:
What is the primary function of chloroplasts in plant cells?
A. Cellular respiration
B. Protein synthesis
C. Photosynthesis
D. Lipid storage
CORRECT ANSWER:C. Photosynthesis
RATIONALE: Chloroplasts contain chlorophyll and are responsible for converting light
energy into chemical energy through photosynthesis.


QUESTION 9:
What is the role of the Golgi apparatus?
A. DNA replication
B. Modifying, sorting, and packaging proteins
C. Cellular respiration
D. Lipid synthesis
CORRECT ANSWER:B. Modifying, sorting, and packaging proteins
RATIONALE: The Golgi apparatus processes proteins synthesized in the endoplasmic
reticulum before they are transported to their final destinations.


QUESTION 10:
What is the primary cause of the greenhouse effect?
A. Increased oxygen levels
B. Deforestation
C. Accumulation of greenhouse gases in the atmosphere
D. Increased water vapor
CORRECT ANSWER:C. Accumulation of greenhouse gases in the atmosphere
RATIONALE: The greenhouse effect occurs when greenhouse gases trap heat in the
atmosphere, leading to global warming and climate change.


QUESTION 11:

, What is the primary function of the liver in metabolism?
A. To produce insulin
B. To digest food
C. To regulate blood glucose levels
D. To filter blood
CORRECT ANSWER:C. To regulate blood glucose levels
RATIONALE: The liver plays a crucial role in regulating blood glucose levels by storing
glycogen and releasing glucose as needed.


QUESTION 12:
What is the primary role of the cytoskeleton?
A. To synthesize proteins
B. To provide structural support and facilitate movement
C. To produce energy
D. To store genetic information
CORRECT ANSWER:B. To provide structural support and facilitate movement
RATIONALE: The cytoskeleton is a network of fibers that provides shape to the cell and
aids in cellular movement.


QUESTION 13:
What is the primary purpose of meiosis?
A. To produce identical cells
B. To produce gametes for sexual reproduction
C. To repair tissues
D. To increase cell size
CORRECT ANSWER:B. To produce gametes for sexual reproduction
RATIONALE: Meiosis is a specialized form of cell division that results in the formation
of gametes, reducing the chromosome number by half.


QUESTION 14:
What is the main function of the large intestine?
A. Nutrient absorption
B. Water absorption and feces formation
C. Digestion of proteins
D. Enzyme production