1|Page
Y420/01 Mark Scheme 2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS WILL
COME FROM HERE (100% CORRECT ANSWERS A+ GRADED
1. Which of the following best describes the primary function of
mitochondria?
A. Protein synthesis
B. Lipid degradation
C. ATP production
D. Carbohydrate storage
Answer: C
Explanation: Mitochondria are the primary site of oxidative
phosphorylation, where the electron transport chain and ATP synthase
produce the majority of cellular ATP.
2. In eukaryotic cells, transcription occurs in which location?
A. Cytoplasm
B. Nucleus
C. Ribosome
D. Golgi apparatus
Answer: B
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Explanation: Transcription, the synthesis of RNA from a DNA template,
occurs in the nucleus where the genetic material is housed, allowing for
post-transcriptional modification before translation in the cytoplasm.
3. What type of chemical bond is formed by the sharing of electron
pairs between atoms?
A. Ionic bond
B. Hydrogen bond
C. Covalent bond
D. Van der Waals interaction
Answer: C
Explanation: A covalent bond involves the sharing of one or more pairs
of electrons between two atoms, creating a stable balance of attractive
and repulsive forces.
4. The second law of thermodynamics states that for any spontaneous
process, the entropy of the universe:
A. Decreases
B. Remains constant
C. Increases
D. Becomes zero
Answer: C
Explanation: The second law dictates that the total entropy of an
isolated system, and by extension the universe, always increases over
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time, reflecting the direction of spontaneous change towards greater
disorder.
5. Which organelle is responsible for modifying, sorting, and packaging
proteins for secretion?
A. Smooth endoplasmic reticulum
B. Lysosome
C. Peroxisome
D. Golgi apparatus
Answer: D
Explanation: The Golgi apparatus functions as a central hub in the
endomembrane system, receiving proteins from the rough ER,
modifying them (e.g., glycosylation), and sorting them into vesicles for
transport to various destinations.
6. In a neuron at rest, the membrane potential is primarily maintained
by:
A. Voltage-gated sodium channels
B. The sodium-potassium pump
C. Ligand-gated chloride channels
D. Calcium ion leakage
Answer: B
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Explanation: The Na+/K+-ATPase pump actively transports three Na+
ions out and two K+ ions in, establishing and maintaining the
concentration gradients crucial for the resting membrane potential.
7. What is the fundamental unit of heredity?
A. Chromosome
B. Genome
C. Gene
D. Nucleotide
Answer: C
Explanation: A gene is the basic physical and functional unit of heredity,
a specific sequence of nucleotides in DNA or RNA that encodes the
synthesis of a functional product, usually a protein.
8. Which of the following molecules is the primary energy currency of
the cell?
A. Glucose
B. NADH
C. GTP
D. ATP
Answer: D
Explanation: Adenosine triphosphate (ATP) has high-energy
phosphoanhydride bonds whose hydrolysis releases energy to drive a
vast array of endergonic cellular processes.
Y420/01 Mark Scheme 2026-2027 BANK QUESTIONS WITH
DETAILED VERIFIED ANSWERS EXAM QUESTIONS WILL
COME FROM HERE (100% CORRECT ANSWERS A+ GRADED
1. Which of the following best describes the primary function of
mitochondria?
A. Protein synthesis
B. Lipid degradation
C. ATP production
D. Carbohydrate storage
Answer: C
Explanation: Mitochondria are the primary site of oxidative
phosphorylation, where the electron transport chain and ATP synthase
produce the majority of cellular ATP.
2. In eukaryotic cells, transcription occurs in which location?
A. Cytoplasm
B. Nucleus
C. Ribosome
D. Golgi apparatus
Answer: B
,2|Page
Explanation: Transcription, the synthesis of RNA from a DNA template,
occurs in the nucleus where the genetic material is housed, allowing for
post-transcriptional modification before translation in the cytoplasm.
3. What type of chemical bond is formed by the sharing of electron
pairs between atoms?
A. Ionic bond
B. Hydrogen bond
C. Covalent bond
D. Van der Waals interaction
Answer: C
Explanation: A covalent bond involves the sharing of one or more pairs
of electrons between two atoms, creating a stable balance of attractive
and repulsive forces.
4. The second law of thermodynamics states that for any spontaneous
process, the entropy of the universe:
A. Decreases
B. Remains constant
C. Increases
D. Becomes zero
Answer: C
Explanation: The second law dictates that the total entropy of an
isolated system, and by extension the universe, always increases over
,3|Page
time, reflecting the direction of spontaneous change towards greater
disorder.
5. Which organelle is responsible for modifying, sorting, and packaging
proteins for secretion?
A. Smooth endoplasmic reticulum
B. Lysosome
C. Peroxisome
D. Golgi apparatus
Answer: D
Explanation: The Golgi apparatus functions as a central hub in the
endomembrane system, receiving proteins from the rough ER,
modifying them (e.g., glycosylation), and sorting them into vesicles for
transport to various destinations.
6. In a neuron at rest, the membrane potential is primarily maintained
by:
A. Voltage-gated sodium channels
B. The sodium-potassium pump
C. Ligand-gated chloride channels
D. Calcium ion leakage
Answer: B
, 4|Page
Explanation: The Na+/K+-ATPase pump actively transports three Na+
ions out and two K+ ions in, establishing and maintaining the
concentration gradients crucial for the resting membrane potential.
7. What is the fundamental unit of heredity?
A. Chromosome
B. Genome
C. Gene
D. Nucleotide
Answer: C
Explanation: A gene is the basic physical and functional unit of heredity,
a specific sequence of nucleotides in DNA or RNA that encodes the
synthesis of a functional product, usually a protein.
8. Which of the following molecules is the primary energy currency of
the cell?
A. Glucose
B. NADH
C. GTP
D. ATP
Answer: D
Explanation: Adenosine triphosphate (ATP) has high-energy
phosphoanhydride bonds whose hydrolysis releases energy to drive a
vast array of endergonic cellular processes.
