McCance & Huether’s Pathophysiology
The Biologic Basis for Disease in Adults
and Children
9th Edition
Author(s)Julia Rogers
TEST BANK
Q1. A 6-year-old boy is diagnosed with a mitochondrial
cytopathy after progressive exercise intolerance, lactic
acidosis, and muscle weakness. Muscle biopsy
demonstrates structurally abnormal mitochondria with
impaired oxidative phosphorylation. The patient’s fatigue
is most directly explained by failure of which cellular
process?
, A. Cytoplasmic glycolysis generating pyruvate
B. Ribosomal assembly of contractile proteins
C. Mitochondrial ATP generation through electron
transport
D. Lysosomal degradation of glycogen
E. Peroxisomal beta-oxidation of very-long-chain fatty
acids
Correct Answer: C
Rationale:
• Clinical Clue: Lactic acidosis and exercise intolerance
strongly suggest impaired aerobic metabolism.
• Mechanism: Mitochondria generate ATP through oxidative
phosphorylation within the electron transport chain.
• Why the Correct Answer Is Right: Defective oxidative
phosphorylation severely limits ATP availability in high-
energy tissues such as skeletal muscle.
• Why the Other Options Are Wrong:
o A: Glycolysis still occurs in the cytoplasm and often
increases compensatorily.
o B: Ribosomal protein synthesis is not the primary
energy-producing pathway.
o D: Lysosomes digest intracellular material rather than
generate ATP.
, o E: Peroxisomes participate in lipid metabolism but are
not major ATP generators.
• Exam Trap: Increased lactate reflects preserved anaerobic
glycolysis despite failed aerobic ATP production.
• High-Yield Clinical Correlation: Mitochondrial dysfunction
commonly affects muscle, brain, and cardiac tissue
because of high metabolic demand.
• Memory Anchor: “Mitochondria = maximal ATP.”
Q2. A researcher studying membrane physiology exposes
hepatocytes to a toxin that selectively inhibits Na+/K+-
ATPase activity. Which immediate cellular change is most
likely to occur?
A. Hyperpolarization from potassium influx
B. Cellular swelling from osmotic sodium accumulation
C. Accelerated calcium export from the cytoplasm
D. Increased secondary active glucose transport
E. Enhanced mitochondrial membrane potential
Correct Answer: B
Rationale:
• Clinical Clue: Na+/K+-ATPase maintains ionic gradients and
cellular volume.
, • Mechanism: Failure of sodium extrusion causes
intracellular sodium accumulation followed by osmotic
water influx.
• Why the Correct Answer Is Right: Loss of ATP-dependent
ion pumping leads rapidly to cellular swelling.
• Why the Other Options Are Wrong:
o A: Membrane depolarization—not
hyperpolarization—occurs.
o C: Calcium tends to accumulate intracellularly.
o D: Secondary active transport decreases because
sodium gradients collapse.
o E: Mitochondrial membrane potential is unrelated to
this membrane pump directly.
• Exam Trap: Cell swelling is among the earliest reversible
forms of cell injury.
• High-Yield Clinical Correlation: Ischemic injury commonly
impairs Na+/K+-ATPase due to ATP depletion.
• Memory Anchor: “Pump failure → sodium stays → water
follows.”
Q3. A patient with metastatic carcinoma is found to have
loss of E-cadherin expression on tumor biopsy. This
The Biologic Basis for Disease in Adults
and Children
9th Edition
Author(s)Julia Rogers
TEST BANK
Q1. A 6-year-old boy is diagnosed with a mitochondrial
cytopathy after progressive exercise intolerance, lactic
acidosis, and muscle weakness. Muscle biopsy
demonstrates structurally abnormal mitochondria with
impaired oxidative phosphorylation. The patient’s fatigue
is most directly explained by failure of which cellular
process?
, A. Cytoplasmic glycolysis generating pyruvate
B. Ribosomal assembly of contractile proteins
C. Mitochondrial ATP generation through electron
transport
D. Lysosomal degradation of glycogen
E. Peroxisomal beta-oxidation of very-long-chain fatty
acids
Correct Answer: C
Rationale:
• Clinical Clue: Lactic acidosis and exercise intolerance
strongly suggest impaired aerobic metabolism.
• Mechanism: Mitochondria generate ATP through oxidative
phosphorylation within the electron transport chain.
• Why the Correct Answer Is Right: Defective oxidative
phosphorylation severely limits ATP availability in high-
energy tissues such as skeletal muscle.
• Why the Other Options Are Wrong:
o A: Glycolysis still occurs in the cytoplasm and often
increases compensatorily.
o B: Ribosomal protein synthesis is not the primary
energy-producing pathway.
o D: Lysosomes digest intracellular material rather than
generate ATP.
, o E: Peroxisomes participate in lipid metabolism but are
not major ATP generators.
• Exam Trap: Increased lactate reflects preserved anaerobic
glycolysis despite failed aerobic ATP production.
• High-Yield Clinical Correlation: Mitochondrial dysfunction
commonly affects muscle, brain, and cardiac tissue
because of high metabolic demand.
• Memory Anchor: “Mitochondria = maximal ATP.”
Q2. A researcher studying membrane physiology exposes
hepatocytes to a toxin that selectively inhibits Na+/K+-
ATPase activity. Which immediate cellular change is most
likely to occur?
A. Hyperpolarization from potassium influx
B. Cellular swelling from osmotic sodium accumulation
C. Accelerated calcium export from the cytoplasm
D. Increased secondary active glucose transport
E. Enhanced mitochondrial membrane potential
Correct Answer: B
Rationale:
• Clinical Clue: Na+/K+-ATPase maintains ionic gradients and
cellular volume.
, • Mechanism: Failure of sodium extrusion causes
intracellular sodium accumulation followed by osmotic
water influx.
• Why the Correct Answer Is Right: Loss of ATP-dependent
ion pumping leads rapidly to cellular swelling.
• Why the Other Options Are Wrong:
o A: Membrane depolarization—not
hyperpolarization—occurs.
o C: Calcium tends to accumulate intracellularly.
o D: Secondary active transport decreases because
sodium gradients collapse.
o E: Mitochondrial membrane potential is unrelated to
this membrane pump directly.
• Exam Trap: Cell swelling is among the earliest reversible
forms of cell injury.
• High-Yield Clinical Correlation: Ischemic injury commonly
impairs Na+/K+-ATPase due to ATP depletion.
• Memory Anchor: “Pump failure → sodium stays → water
follows.”
Q3. A patient with metastatic carcinoma is found to have
loss of E-cadherin expression on tumor biopsy. This
