BIOLOGY 1113H Final Exam Prep 2026 | 200 Practice
Questions with Answers & Explanations | Biology Study Guide
SECTION A – Cell Structure, Function & Metabolism
1. A researcher treats cells with a drug that blocks the function of the signal recognition particle (SRP).
Which of the following proteins would be most directly affected?
A. Cytosolic actin
B. DNA polymerase
C. Insulin (a secreted hormone)
D. Hexokinase (glycolytic enzyme)
Answer: C
Explanation: SRP targets ribosomes to the ER for secretion or membrane insertion; insulin is secreted, so
its translation would be impaired.
2. A patient has a mitochondrial disorder that specifically impairs Complex III of the electron transport
chain. Which of the following will accumulate?
A. NADH
B. FADH₂
C. Cytochrome c (reduced)
D. Ubiquinol (CoQH₂)
Answer: D
Explanation: Complex III oxidizes ubiquinol (CoQH₂); if blocked, ubiquinol accumulates upstream.
3. A cell is placed in a hypotonic solution containing a membrane-impermeant solute. Initially, the cell
swells. After 30 minutes, it returns to normal volume. This is best explained by:
A. Activation of a Na⁺/K⁺ ATPase
B. Efflux of intracellular osmolytes via volume-regulated anion channels
C. Endocytosis of excess water
D. Aquaporin closure
,Answer: B
Explanation: Regulatory volume decrease (RVD) occurs via loss of K⁺, Cl⁻, and organic osmolytes through
specialized channels.
4. In an experiment, isolated mitochondria are supplied with succinate and ADP. Oxygen consumption is
measured. Then, oligomycin is added. What happens to oxygen consumption?
A. Increases sharply
B. Decreases to near zero
C. No change
D. Increases then decreases
Answer: B
Explanation: Oligomycin inhibits ATP synthase, creating a proton gradient that stops electron flow and
O₂ consumption.
5. A mutation in the gene encoding the mitochondrial pyruvate carrier (MPC) causes severe lactic
acidosis. Which metabolic intermediate would accumulate in the cytosol?
A. Oxaloacetate
B. Citrate
C. Pyruvate
D. Acetyl-CoA
Answer: C
Explanation: Pyruvate cannot enter mitochondria for oxidation; it is converted to lactate by LDH, causing
acidosis.
6. A scientist uses FRAP (fluorescence recovery after photobleaching) to measure membrane protein
mobility. A protein shows very slow recovery. This suggests:
A. The protein is bound to the cytoskeleton
B. The membrane has high cholesterol content
C. The protein is in a liquid-ordered phase
D. All of the above
Answer: D
,Explanation: Cytoskeletal anchoring, high cholesterol, and lipid rafts (liquid-ordered) all restrict protein
diffusion.
7. A cell line is deficient in clathrin. Which of the following processes would still occur normally?
A. Receptor-mediated endocytosis of LDL
B. Phagocytosis of bacteria by macrophages
C. Retrieval of synaptic vesicles
D. Formation of COPII vesicles from the ER
Answer: B
Explanation: Phagocytosis is actin-based and does not require clathrin; receptor-mediated endocytosis
and synaptic vesicle recycling require clathrin.
8. You are studying an enzyme that follows Michaelis-Menten kinetics. In the presence of an
uncompetitive inhibitor, which of the following changes occurs?
A. Kₘ increases, Vmax decreases
B. Kₘ decreases, Vmax decreases
C. Kₘ increases, Vmax unchanged
D. Kₘ unchanged, Vmax decreases
Answer: B
Explanation: Uncompetitive inhibitor binds only to ES complex, decreasing both Kₘ and Vmax
(apparent).
9. A tumor cell line exhibits high rates of aerobic glycolysis (Warburg effect). Compared to normal cells,
these tumor cells have:
A. Higher mitochondrial membrane potential
B. Increased conversion of pyruvate to lactate
C. Increased fatty acid oxidation
D. Decreased glucose uptake
Answer: B
Explanation: Warburg effect: even with oxygen, pyruvate is converted to lactate via LDHA, not entering
TCA cycle.
, 10. A drug that inhibits the V-type ATPase in lysosomes would most directly impair:
A. Receptor recycling
B. Acidification of the lysosomal lumen
C. Autophagy initiation
D. Phagosome formation
Answer: B
Explanation: V-ATPase pumps H⁺ into lysosomes; inhibition raises pH, impairing hydrolytic enzyme
activity.
11. A mutation in the active site of glycogen phosphorylase prevents binding of glucose-6-phosphate
(G6P). How does this affect glycogen breakdown?
A. Constitutively active, even when blood glucose is high
B. Completely inactive
C. Only active during exercise
D. No change
Answer: A
Explanation: G6P is an allosteric inhibitor; without binding, inhibition is lost, and enzyme remains active.
12. A cell is treated with brefeldin A, which disassembles the Golgi apparatus. Which of the following
would be immediately blocked?
A. Transport of proteins from ER to Golgi
B. Endocytosis from the plasma membrane
C. Retrograde transport from Golgi to ER
D. Exocytosis of secretory vesicles
Answer: A
Explanation: Brefeldin A inhibits COPI-mediated transport, causing Golgi to merge with ER, blocking ER-
to-Golgi traffic.
Questions with Answers & Explanations | Biology Study Guide
SECTION A – Cell Structure, Function & Metabolism
1. A researcher treats cells with a drug that blocks the function of the signal recognition particle (SRP).
Which of the following proteins would be most directly affected?
A. Cytosolic actin
B. DNA polymerase
C. Insulin (a secreted hormone)
D. Hexokinase (glycolytic enzyme)
Answer: C
Explanation: SRP targets ribosomes to the ER for secretion or membrane insertion; insulin is secreted, so
its translation would be impaired.
2. A patient has a mitochondrial disorder that specifically impairs Complex III of the electron transport
chain. Which of the following will accumulate?
A. NADH
B. FADH₂
C. Cytochrome c (reduced)
D. Ubiquinol (CoQH₂)
Answer: D
Explanation: Complex III oxidizes ubiquinol (CoQH₂); if blocked, ubiquinol accumulates upstream.
3. A cell is placed in a hypotonic solution containing a membrane-impermeant solute. Initially, the cell
swells. After 30 minutes, it returns to normal volume. This is best explained by:
A. Activation of a Na⁺/K⁺ ATPase
B. Efflux of intracellular osmolytes via volume-regulated anion channels
C. Endocytosis of excess water
D. Aquaporin closure
,Answer: B
Explanation: Regulatory volume decrease (RVD) occurs via loss of K⁺, Cl⁻, and organic osmolytes through
specialized channels.
4. In an experiment, isolated mitochondria are supplied with succinate and ADP. Oxygen consumption is
measured. Then, oligomycin is added. What happens to oxygen consumption?
A. Increases sharply
B. Decreases to near zero
C. No change
D. Increases then decreases
Answer: B
Explanation: Oligomycin inhibits ATP synthase, creating a proton gradient that stops electron flow and
O₂ consumption.
5. A mutation in the gene encoding the mitochondrial pyruvate carrier (MPC) causes severe lactic
acidosis. Which metabolic intermediate would accumulate in the cytosol?
A. Oxaloacetate
B. Citrate
C. Pyruvate
D. Acetyl-CoA
Answer: C
Explanation: Pyruvate cannot enter mitochondria for oxidation; it is converted to lactate by LDH, causing
acidosis.
6. A scientist uses FRAP (fluorescence recovery after photobleaching) to measure membrane protein
mobility. A protein shows very slow recovery. This suggests:
A. The protein is bound to the cytoskeleton
B. The membrane has high cholesterol content
C. The protein is in a liquid-ordered phase
D. All of the above
Answer: D
,Explanation: Cytoskeletal anchoring, high cholesterol, and lipid rafts (liquid-ordered) all restrict protein
diffusion.
7. A cell line is deficient in clathrin. Which of the following processes would still occur normally?
A. Receptor-mediated endocytosis of LDL
B. Phagocytosis of bacteria by macrophages
C. Retrieval of synaptic vesicles
D. Formation of COPII vesicles from the ER
Answer: B
Explanation: Phagocytosis is actin-based and does not require clathrin; receptor-mediated endocytosis
and synaptic vesicle recycling require clathrin.
8. You are studying an enzyme that follows Michaelis-Menten kinetics. In the presence of an
uncompetitive inhibitor, which of the following changes occurs?
A. Kₘ increases, Vmax decreases
B. Kₘ decreases, Vmax decreases
C. Kₘ increases, Vmax unchanged
D. Kₘ unchanged, Vmax decreases
Answer: B
Explanation: Uncompetitive inhibitor binds only to ES complex, decreasing both Kₘ and Vmax
(apparent).
9. A tumor cell line exhibits high rates of aerobic glycolysis (Warburg effect). Compared to normal cells,
these tumor cells have:
A. Higher mitochondrial membrane potential
B. Increased conversion of pyruvate to lactate
C. Increased fatty acid oxidation
D. Decreased glucose uptake
Answer: B
Explanation: Warburg effect: even with oxygen, pyruvate is converted to lactate via LDHA, not entering
TCA cycle.
, 10. A drug that inhibits the V-type ATPase in lysosomes would most directly impair:
A. Receptor recycling
B. Acidification of the lysosomal lumen
C. Autophagy initiation
D. Phagosome formation
Answer: B
Explanation: V-ATPase pumps H⁺ into lysosomes; inhibition raises pH, impairing hydrolytic enzyme
activity.
11. A mutation in the active site of glycogen phosphorylase prevents binding of glucose-6-phosphate
(G6P). How does this affect glycogen breakdown?
A. Constitutively active, even when blood glucose is high
B. Completely inactive
C. Only active during exercise
D. No change
Answer: A
Explanation: G6P is an allosteric inhibitor; without binding, inhibition is lost, and enzyme remains active.
12. A cell is treated with brefeldin A, which disassembles the Golgi apparatus. Which of the following
would be immediately blocked?
A. Transport of proteins from ER to Golgi
B. Endocytosis from the plasma membrane
C. Retrograde transport from Golgi to ER
D. Exocytosis of secretory vesicles
Answer: A
Explanation: Brefeldin A inhibits COPI-mediated transport, causing Golgi to merge with ER, blocking ER-
to-Golgi traffic.
