NURS 6501 Advanced Pathophysiology Final Exam
Week 11 Question Bank (Latest 2026/2027 Edition) –
Questions, Answers & Detailed Rationales
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SECTION 1: Cellular Pathophysiology and Genetic Mechanisms
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Question 1
A 58-year-old male presents with progressive muscle weakness, ptosis, and diplopia
that worsen with sustained activity and improve with rest. Muscle biopsy reveals
antibody-mediated destruction of acetylcholine receptors at the neuromuscular
junction. Which underlying pathophysiological mechanism best explains the etiology of
this disorder?
A. Direct cellular injury from cytotoxic T-lymphocyte-mediated destruction of motor end
plates
B. Type II hypersensitivity reaction involving autoantibodies against postsynaptic
acetylcholine receptors
C. Type III hypersensitivity reaction with immune complex deposition at the
neuromuscular junction
D. Defective chloride channel function leading to sustained muscle depolarization
Correct Answer:
B — Type II hypersensitivity reaction involving autoantibodies against postsynaptic
acetylcholine receptors
Rationale:
Myasthenia gravis is a classic type II hypersensitivity disorder where IgG autoantibodies
bind to and downregulate postsynaptic acetylcholine receptors, impairing
neuromuscular transmission. Distractor A incorrectly describes a cytotoxic T-cell
,mechanism more characteristic of type IV hypersensitivity, while C describes immune
complex deposition seen in disorders like systemic lupus erythematosus.
Question 2
A 34-year-old woman with a family history of breast cancer undergoes genetic testing
and is found to have a mutation in the BRCA1 gene. Which pathophysiological
consequence of this mutation most directly contributes to malignant transformation?
A. Defective DNA mismatch repair leading to microsatellite instability
B. Impaired homologous recombination repair of double-strand DNA breaks
C. Activation of proto-oncogenes through chromosomal translocation
D. Failure of apoptosis due to loss of tumor suppressor gene p53 function
Correct Answer:
B — Impaired homologous recombination repair of double-strand DNA breaks
Rationale:
BRCA1 is a tumor suppressor gene that functions in homologous recombination repair
of double-strand DNA breaks; loss of this function leads to genomic instability and
carcinogenesis. Distractor A describes Lynch syndrome (MLH1/MSH2 mutations), while
D incorrectly attributes p53 loss as the primary BRCA1 mechanism.
Question 3
A 62-year-old male with chronic alcoholism presents with confusion, ataxia,
ophthalmoplegia, and memory deficits. Brain MRI reveals mammillary body atrophy and
thalamic nuclei changes. Which cellular pathophysiological process is most directly
responsible for these findings?
A. Thiamine pyrophosphate deficiency impairing aerobic metabolism and ATP
production
B. Direct ethanol toxicity causing neuronal apoptosis via glutamate excitotoxicity
C. Acetaldehyde accumulation leading to lipid peroxidation and membrane damage
,D. Vitamin B12 deficiency causing demyelination of posterior columns
Correct Answer:
A — Thiamine pyrophosphate deficiency impairing aerobic metabolism and ATP
production
Rationale:
Wernicke-Korsakoff syndrome results from thiamine (vitamin B1) deficiency, where
thiamine pyrophosphate serves as a cofactor for critical enzymes in glucose
metabolism; deficiency causes lactic acidosis, cellular energy failure, and neuronal
death in vulnerable brain regions. Distractor D describes subacute combined
degeneration of the spinal cord, not the described triad.
Question 4
A 45-year-old patient receiving chemotherapy with doxorubicin develops
dose-dependent cardiomyopathy. Which cellular mechanism best explains the
pathophysiology of this adverse effect?
A. Inhibition of topoisomerase II leading to DNA strand breaks in cardiomyocytes
B. Generation of reactive oxygen species and iron-mediated free radical damage to
cardiac myocytes
C. Blockade of HER2/neu receptors resulting in impaired cardiac contractility
D. Disruption of microtubule assembly interfering with cardiomyocyte cytoskeletal
integrity
Correct Answer:
B — Generation of reactive oxygen species and iron-mediated free radical damage to
cardiac myocytes
Rationale:
Doxorubicin undergoes redox cycling, generating superoxide radicals and hydroxyl
radicals via iron-mediated Fenton chemistry, causing oxidative damage to cardiac
, mitochondria and membranes. Distractor A describes the antineoplastic mechanism
but not the cardiotoxic mechanism, while D describes paclitaxel's mechanism.
Question 5
A newborn infant presents with severe hypotonia, feeding difficulties, and
hepatomegaly. Laboratory studies reveal hypoglycemia, lactic acidosis, and elevated
liver enzymes. Muscle biopsy shows ragged red fibers. Which underlying
pathophysiological defect is most likely responsible?
A. Deficiency of acid alpha-glucosidase (Pompe disease)
B. Mutation in mitochondrial DNA affecting oxidative phosphorylation complexes
C. Deficiency of medium-chain acyl-CoA dehydrogenase (MCAD)
D. Defective peroxisomal biogenesis (Zellweger syndrome)
Correct Answer:
B — Mutation in mitochondrial DNA affecting oxidative phosphorylation complexes
Rationale:
The presentation of hypotonia, lactic acidosis, hypoglycemia, and ragged red fibers on
muscle biopsy is pathognomonic for mitochondrial myopathy resulting from mutations
in mitochondrial DNA encoding oxidative phosphorylation complexes. Distractor A
(Pomce disease) presents with cardiomegaly and does not cause ragged red fibers,
while C (MCAD deficiency) presents with fasting hypoketotic hypoglycemia without
lactic acidosis or ragged red fibers.
Question 6
A 28-year-old male presents with recurrent venous thrombosis and pulmonary
embolism. Laboratory studies reveal a prolonged activated protein C (APC) resistance
assay. Which molecular defect is most likely responsible for this patient's
hypercoagulable state?
Week 11 Question Bank (Latest 2026/2027 Edition) –
Questions, Answers & Detailed Rationales
──────────────────────────────
SECTION 1: Cellular Pathophysiology and Genetic Mechanisms
──────────────────────────────
Question 1
A 58-year-old male presents with progressive muscle weakness, ptosis, and diplopia
that worsen with sustained activity and improve with rest. Muscle biopsy reveals
antibody-mediated destruction of acetylcholine receptors at the neuromuscular
junction. Which underlying pathophysiological mechanism best explains the etiology of
this disorder?
A. Direct cellular injury from cytotoxic T-lymphocyte-mediated destruction of motor end
plates
B. Type II hypersensitivity reaction involving autoantibodies against postsynaptic
acetylcholine receptors
C. Type III hypersensitivity reaction with immune complex deposition at the
neuromuscular junction
D. Defective chloride channel function leading to sustained muscle depolarization
Correct Answer:
B — Type II hypersensitivity reaction involving autoantibodies against postsynaptic
acetylcholine receptors
Rationale:
Myasthenia gravis is a classic type II hypersensitivity disorder where IgG autoantibodies
bind to and downregulate postsynaptic acetylcholine receptors, impairing
neuromuscular transmission. Distractor A incorrectly describes a cytotoxic T-cell
,mechanism more characteristic of type IV hypersensitivity, while C describes immune
complex deposition seen in disorders like systemic lupus erythematosus.
Question 2
A 34-year-old woman with a family history of breast cancer undergoes genetic testing
and is found to have a mutation in the BRCA1 gene. Which pathophysiological
consequence of this mutation most directly contributes to malignant transformation?
A. Defective DNA mismatch repair leading to microsatellite instability
B. Impaired homologous recombination repair of double-strand DNA breaks
C. Activation of proto-oncogenes through chromosomal translocation
D. Failure of apoptosis due to loss of tumor suppressor gene p53 function
Correct Answer:
B — Impaired homologous recombination repair of double-strand DNA breaks
Rationale:
BRCA1 is a tumor suppressor gene that functions in homologous recombination repair
of double-strand DNA breaks; loss of this function leads to genomic instability and
carcinogenesis. Distractor A describes Lynch syndrome (MLH1/MSH2 mutations), while
D incorrectly attributes p53 loss as the primary BRCA1 mechanism.
Question 3
A 62-year-old male with chronic alcoholism presents with confusion, ataxia,
ophthalmoplegia, and memory deficits. Brain MRI reveals mammillary body atrophy and
thalamic nuclei changes. Which cellular pathophysiological process is most directly
responsible for these findings?
A. Thiamine pyrophosphate deficiency impairing aerobic metabolism and ATP
production
B. Direct ethanol toxicity causing neuronal apoptosis via glutamate excitotoxicity
C. Acetaldehyde accumulation leading to lipid peroxidation and membrane damage
,D. Vitamin B12 deficiency causing demyelination of posterior columns
Correct Answer:
A — Thiamine pyrophosphate deficiency impairing aerobic metabolism and ATP
production
Rationale:
Wernicke-Korsakoff syndrome results from thiamine (vitamin B1) deficiency, where
thiamine pyrophosphate serves as a cofactor for critical enzymes in glucose
metabolism; deficiency causes lactic acidosis, cellular energy failure, and neuronal
death in vulnerable brain regions. Distractor D describes subacute combined
degeneration of the spinal cord, not the described triad.
Question 4
A 45-year-old patient receiving chemotherapy with doxorubicin develops
dose-dependent cardiomyopathy. Which cellular mechanism best explains the
pathophysiology of this adverse effect?
A. Inhibition of topoisomerase II leading to DNA strand breaks in cardiomyocytes
B. Generation of reactive oxygen species and iron-mediated free radical damage to
cardiac myocytes
C. Blockade of HER2/neu receptors resulting in impaired cardiac contractility
D. Disruption of microtubule assembly interfering with cardiomyocyte cytoskeletal
integrity
Correct Answer:
B — Generation of reactive oxygen species and iron-mediated free radical damage to
cardiac myocytes
Rationale:
Doxorubicin undergoes redox cycling, generating superoxide radicals and hydroxyl
radicals via iron-mediated Fenton chemistry, causing oxidative damage to cardiac
, mitochondria and membranes. Distractor A describes the antineoplastic mechanism
but not the cardiotoxic mechanism, while D describes paclitaxel's mechanism.
Question 5
A newborn infant presents with severe hypotonia, feeding difficulties, and
hepatomegaly. Laboratory studies reveal hypoglycemia, lactic acidosis, and elevated
liver enzymes. Muscle biopsy shows ragged red fibers. Which underlying
pathophysiological defect is most likely responsible?
A. Deficiency of acid alpha-glucosidase (Pompe disease)
B. Mutation in mitochondrial DNA affecting oxidative phosphorylation complexes
C. Deficiency of medium-chain acyl-CoA dehydrogenase (MCAD)
D. Defective peroxisomal biogenesis (Zellweger syndrome)
Correct Answer:
B — Mutation in mitochondrial DNA affecting oxidative phosphorylation complexes
Rationale:
The presentation of hypotonia, lactic acidosis, hypoglycemia, and ragged red fibers on
muscle biopsy is pathognomonic for mitochondrial myopathy resulting from mutations
in mitochondrial DNA encoding oxidative phosphorylation complexes. Distractor A
(Pomce disease) presents with cardiomegaly and does not cause ragged red fibers,
while C (MCAD deficiency) presents with fasting hypoketotic hypoglycemia without
lactic acidosis or ragged red fibers.
Question 6
A 28-year-old male presents with recurrent venous thrombosis and pulmonary
embolism. Laboratory studies reveal a prolonged activated protein C (APC) resistance
assay. Which molecular defect is most likely responsible for this patient's
hypercoagulable state?
