PATHOPHYSIOLOGY: 2ND EDITION BY NANCY TKACS
AND LINDA HERRMANN ALL CHAPTERS| VERIFIED
QUESTION AND ANSWERS| ISBN-978-
0826167552|LATEST VERSION 2025/2026
,Cellular & Molecular Physiology
Q1.
Which ion movement primarily determines a neuron’s resting membrane
potential?
A. Sodium influx through leak channels
B. Potassium efflux through leak channels
C. Calcium influx through voltage-gated channels
D. Chloride efflux through GABA receptors
Answer: B. Potassium efflux through leak channels
Rationale: Resting potential (~-70 mV) lies near the K⁺ equilibrium because
neuronal membranes are most permeable to K⁺ at rest.
Q2.
Hypoxia stabilizes which transcription factor to upregulate erythropoietin?
A. NF-κB
B. HIF-1α
C. CREB
D. STAT3
Answer: B. HIF-1α
Rationale: Low O₂ prevents HIF-1α degradation, allowing transcription of
hypoxia-responsive genes including EPO.
Q3.
Loss of Na⁺/K⁺ ATPase activity leads to:
A. Cell shrinkage from water loss
B. Intracellular K⁺ accumulation
C. Intracellular Na⁺ accumulation and cell swelling
D. Hyperpolarization of the membrane
,Answer: C. Intracellular Na⁺ accumulation and cell swelling
Rationale: Pump failure → Na⁺ stays inside, water follows → swelling; K⁺
decreases, not increases.
Q4.
Primary ATP source in hypoxic myocardium is:
A. Fatty-acid oxidation
B. Anaerobic glycolysis
C. Oxidative phosphorylation
D. Protein catabolism
Answer: B. Anaerobic glycolysis
Rationale: Without O₂, oxidative phosphorylation halts and glycolysis with
lactate production predominates.
Q5.
The intrinsic apoptotic pathway is initiated by which organelle?
A. Endoplasmic reticulum
B. Golgi apparatus
C. Mitochondria
D. Lysosome
Answer: C. Mitochondria
Rationale: Cytochrome c release from mitochondria activates caspase
cascades.
Q6.
ATP synthase is powered by:
A. Sodium gradient across outer mitochondrial membrane
B. Proton gradient across inner mitochondrial membrane
, C. Calcium influx into the matrix
D. Direct NADH oxidation at ATP synthase
Answer: B. Proton gradient across inner mitochondrial membrane
Rationale: The proton-motive force generated by the electron transport
chain drives ATP synthase.
Q7.
Which enzyme converts superoxide radicals to hydrogen peroxide?
A. Catalase
B. Glutathione peroxidase
C. Superoxide dismutase
D. Peroxiredoxin
Answer: C. Superoxide dismutase
Rationale: SOD catalyzes 2 O₂⁻ + 2 H⁺ → H₂O₂ + O₂, the first step in free-
radical detoxification.
Q8.
Which is an irreversible sign of cell injury?
A. Cellular swelling
B. Nuclear pyknosis
C. Plasma-membrane blebbing
D. Mitochondrial swelling
Answer: B. Nuclear pyknosis
Rationale: Chromatin condensation/fragmentation signals the point of no
return.