Cell Biology & Molecular Metabolism
Exam 2026/2027: 80 Multiple-Choice
Questions on Cytoskeleton, Mitochondria,
Apoptosis, and Cell Signaling – With
Detailed Explanations
Description:
Master cell biology for 2026/2027 with 80 exam-style MCQs covering energy metabolism,
cytoskeleton dynamics, mitochondrial genetics, apoptosis, synaptic transmission, and
more.
Each question includes correct answers and clear explanations. Perfect for university exam
prep, medical school review, and study guides.
Download the complete 2026/2027 practice exam now and boost your score!
, Cell Biology Exam 2026/2027 – 80 MCQs with Answers
Section A: Energy, Metabolism, and Thermodynamics
1. Organisms store energy during which of the following circumstances?
A. Only during periods of starvation
B. During growth and temporarily during activity
C. Exclusively during sleep cycles
D. Only when ATP levels are depleted
Answer: B
Explanation: Organisms store energy during growth to support biosynthesis and temporarily
during physical activity to meet increased metabolic demands. This stored energy is typically
in the form of ATP, glycogen, or lipids.
2. Approximately what percentage of an organism's genome is dedicated to metabolic
processes?
A. 5%
B. 10%
C. 20%
D. 35%
Answer: C
Explanation: About 20% of the genome encodes enzymes and regulatory proteins involved
in metabolism, reflecting the central importance of metabolic pathways for cellular function
and survival.
3. Which of the following best describes high-quality energy in biological systems?
A. Disordered and randomly distributed
B. Organized and capable of performing work
C. Thermal energy at equilibrium
D. Energy trapped in covalent bonds of carbon dioxide
Answer: B
Explanation: High-quality energy is organized and can perform useful work, such as driving
biosynthetic reactions or mechanical processes. Low-quality energy is disordered, chaotic,
and cannot perform work.
,4. The Gibbs free energy equation is expressed as G = H – TS. In this equation, what does the
term TS represent?
A. Total enthalpy of the system
B. Free energy available for work
C. Energy that is unavailable to do work
D. Temperature-dependent reaction rate
Answer: C
Explanation: In the Gibbs free energy equation, TS represents the energy that is unavailable
to perform work due to entropy (disorder) at a given temperature. G represents free/available
energy, while H is total enthalpy.
5. Cells capture free energy primarily from which molecule?
A. NADH
B. Glucose
C. ATP
D. Oxygen
Answer: C
Explanation: Adenosine triphosphate (ATP) serves as the universal energy currency of cells.
Hydrolysis of ATP releases free energy that drives numerous cellular processes, including
biosynthesis, transport, and mechanical work.
6. The Boltzmann equation for average energy is E = (3/2)kBT. The value of kBT at
physiological temperature (approximately 310 K) is closest to which value?
A. 0.1 kcal/mol
B. 0.6 kcal/mol
C. 1.2 kcal/mol
D. 2.4 kcal/mol
Answer: B
Explanation: At 310 K, kBT ≈ 0.6 kcal/mol (approximately 2.5 kJ/mol). This thermal energy
scale is relevant for molecular motions and diffusion in biological systems.
, Section B: Cytoskeleton Structure and Dynamics
7. Arrange the three major components of the cytoskeleton from thinnest to thickest.
A. Microtubules → Intermediate filaments → Microfilaments
B. Microfilaments → Intermediate filaments → Microtubules
C. Intermediate filaments → Microfilaments → Microtubules
D. Microfilaments → Microtubules → Intermediate filaments
Answer: B
Explanation: Microfilaments (actin filaments) are approximately 7–9 nm in diameter,
intermediate filaments are about 10 nm, and microtubules are the thickest at 25 nm.
8. Which cytoskeletal component is described as having high tensile strength while remaining
flexible, similar to "wires"?
A. Microtubules
B. Intermediate filaments
C. Actin microfilaments
D. Septin filaments
Answer: C
Explanation: Actin microfilaments function like flexible wires with high tensile strength.
Microtubules act as stiff poles resistant to compression, while intermediate filaments behave
like elastic ropes.
9. The Arp2/3 complex nucleates actin filaments at approximately what angle, which is
optimal for pushing against the plasma membrane?
A. 45 degrees
B. 70 degrees
C. 90 degrees
D. 120 degrees
Answer: B
Explanation: The Arp2/3 complex nucleates daughter filaments at a 70-degree angle relative
to the mother filament. This geometry is optimal for generating protrusive forces that push
the plasma membrane forward during cell migration.
Exam 2026/2027: 80 Multiple-Choice
Questions on Cytoskeleton, Mitochondria,
Apoptosis, and Cell Signaling – With
Detailed Explanations
Description:
Master cell biology for 2026/2027 with 80 exam-style MCQs covering energy metabolism,
cytoskeleton dynamics, mitochondrial genetics, apoptosis, synaptic transmission, and
more.
Each question includes correct answers and clear explanations. Perfect for university exam
prep, medical school review, and study guides.
Download the complete 2026/2027 practice exam now and boost your score!
, Cell Biology Exam 2026/2027 – 80 MCQs with Answers
Section A: Energy, Metabolism, and Thermodynamics
1. Organisms store energy during which of the following circumstances?
A. Only during periods of starvation
B. During growth and temporarily during activity
C. Exclusively during sleep cycles
D. Only when ATP levels are depleted
Answer: B
Explanation: Organisms store energy during growth to support biosynthesis and temporarily
during physical activity to meet increased metabolic demands. This stored energy is typically
in the form of ATP, glycogen, or lipids.
2. Approximately what percentage of an organism's genome is dedicated to metabolic
processes?
A. 5%
B. 10%
C. 20%
D. 35%
Answer: C
Explanation: About 20% of the genome encodes enzymes and regulatory proteins involved
in metabolism, reflecting the central importance of metabolic pathways for cellular function
and survival.
3. Which of the following best describes high-quality energy in biological systems?
A. Disordered and randomly distributed
B. Organized and capable of performing work
C. Thermal energy at equilibrium
D. Energy trapped in covalent bonds of carbon dioxide
Answer: B
Explanation: High-quality energy is organized and can perform useful work, such as driving
biosynthetic reactions or mechanical processes. Low-quality energy is disordered, chaotic,
and cannot perform work.
,4. The Gibbs free energy equation is expressed as G = H – TS. In this equation, what does the
term TS represent?
A. Total enthalpy of the system
B. Free energy available for work
C. Energy that is unavailable to do work
D. Temperature-dependent reaction rate
Answer: C
Explanation: In the Gibbs free energy equation, TS represents the energy that is unavailable
to perform work due to entropy (disorder) at a given temperature. G represents free/available
energy, while H is total enthalpy.
5. Cells capture free energy primarily from which molecule?
A. NADH
B. Glucose
C. ATP
D. Oxygen
Answer: C
Explanation: Adenosine triphosphate (ATP) serves as the universal energy currency of cells.
Hydrolysis of ATP releases free energy that drives numerous cellular processes, including
biosynthesis, transport, and mechanical work.
6. The Boltzmann equation for average energy is E = (3/2)kBT. The value of kBT at
physiological temperature (approximately 310 K) is closest to which value?
A. 0.1 kcal/mol
B. 0.6 kcal/mol
C. 1.2 kcal/mol
D. 2.4 kcal/mol
Answer: B
Explanation: At 310 K, kBT ≈ 0.6 kcal/mol (approximately 2.5 kJ/mol). This thermal energy
scale is relevant for molecular motions and diffusion in biological systems.
, Section B: Cytoskeleton Structure and Dynamics
7. Arrange the three major components of the cytoskeleton from thinnest to thickest.
A. Microtubules → Intermediate filaments → Microfilaments
B. Microfilaments → Intermediate filaments → Microtubules
C. Intermediate filaments → Microfilaments → Microtubules
D. Microfilaments → Microtubules → Intermediate filaments
Answer: B
Explanation: Microfilaments (actin filaments) are approximately 7–9 nm in diameter,
intermediate filaments are about 10 nm, and microtubules are the thickest at 25 nm.
8. Which cytoskeletal component is described as having high tensile strength while remaining
flexible, similar to "wires"?
A. Microtubules
B. Intermediate filaments
C. Actin microfilaments
D. Septin filaments
Answer: C
Explanation: Actin microfilaments function like flexible wires with high tensile strength.
Microtubules act as stiff poles resistant to compression, while intermediate filaments behave
like elastic ropes.
9. The Arp2/3 complex nucleates actin filaments at approximately what angle, which is
optimal for pushing against the plasma membrane?
A. 45 degrees
B. 70 degrees
C. 90 degrees
D. 120 degrees
Answer: B
Explanation: The Arp2/3 complex nucleates daughter filaments at a 70-degree angle relative
to the mother filament. This geometry is optimal for generating protrusive forces that push
the plasma membrane forward during cell migration.
