, Question 1
A cell exhibits mitochondrial permeability transition pore opening, cytochrome
c release, and caspase-9 activation. Which form of cell death is most consistent
with these findings?
A. Necrosis
B. Apoptosis
C. Autophagy
D. Necroptosis
Correct Answer: B - Apoptosis
RATIONALE
Intrinsic apoptosis is mediated by mitochondrial outer membrane
permeabilization, cytochrome c release, and caspase-9 activation.
Necrosis lacks caspase activation and involves cell swelling and lysis.
Autophagy is a survival mechanism, and necroptosis is
caspase-independent and involves RIPK1/RIPK3/MLKL signaling.
Question 2
Which epigenetic alteration most directly leads to transcriptional silencing of a
tumor suppressor gene in cancer?
A. Histone acetylation
B. DNA hypomethylation
C. Promoter CpG island hypermethylation
D. Histone phosphorylation
Correct Answer: C - Promoter CpG island hypermethylation
Page 2
, RATIONALE
Hypermethylation of CpG islands in promoter regions recruits
methyl-CpG-binding proteins and histone deacetylases, leading to
chromatin compaction and transcriptional repression. Histone
acetylation generally promotes transcription. DNA hypomethylation
can activate oncogenes but does not silence tumor suppressors.
Histone phosphorylation is involved in DNA repair and condensation,
not direct silencing.
Question 3
In a patient with septic shock, which pathophysiologic mechanism best
explains the observed hypotension refractory to fluid resuscitation?
A. Increased systemic vascular resistance
B. Inducible nitric oxide synthase-mediated vasodilation
C. Enhanced sympathetic outflow
D. Reduced capillary permeability
Correct Answer: B - Inducible nitric oxide synthase-mediated
vasodilation
RATIONALE
Septic shock involves excessive production of nitric oxide via iNOS,
leading to profound vasodilation and hyporesponsiveness to
vasopressors. Systemic vascular resistance is typically low, not high.
Sympathetic outflow is increased but insufficient to compensate.
Capillary permeability is increased, not reduced, contributing to
relative hypovolemia.
Question 4
Which acid-base disturbance is most likely in a patient with chronic obstructive
pulmonary disease (COPD) and a compensatory increase in serum bicarbonate?
A. Acute respiratory alkalosis
B. Chronic respiratory acidosis
Page 3
A cell exhibits mitochondrial permeability transition pore opening, cytochrome
c release, and caspase-9 activation. Which form of cell death is most consistent
with these findings?
A. Necrosis
B. Apoptosis
C. Autophagy
D. Necroptosis
Correct Answer: B - Apoptosis
RATIONALE
Intrinsic apoptosis is mediated by mitochondrial outer membrane
permeabilization, cytochrome c release, and caspase-9 activation.
Necrosis lacks caspase activation and involves cell swelling and lysis.
Autophagy is a survival mechanism, and necroptosis is
caspase-independent and involves RIPK1/RIPK3/MLKL signaling.
Question 2
Which epigenetic alteration most directly leads to transcriptional silencing of a
tumor suppressor gene in cancer?
A. Histone acetylation
B. DNA hypomethylation
C. Promoter CpG island hypermethylation
D. Histone phosphorylation
Correct Answer: C - Promoter CpG island hypermethylation
Page 2
, RATIONALE
Hypermethylation of CpG islands in promoter regions recruits
methyl-CpG-binding proteins and histone deacetylases, leading to
chromatin compaction and transcriptional repression. Histone
acetylation generally promotes transcription. DNA hypomethylation
can activate oncogenes but does not silence tumor suppressors.
Histone phosphorylation is involved in DNA repair and condensation,
not direct silencing.
Question 3
In a patient with septic shock, which pathophysiologic mechanism best
explains the observed hypotension refractory to fluid resuscitation?
A. Increased systemic vascular resistance
B. Inducible nitric oxide synthase-mediated vasodilation
C. Enhanced sympathetic outflow
D. Reduced capillary permeability
Correct Answer: B - Inducible nitric oxide synthase-mediated
vasodilation
RATIONALE
Septic shock involves excessive production of nitric oxide via iNOS,
leading to profound vasodilation and hyporesponsiveness to
vasopressors. Systemic vascular resistance is typically low, not high.
Sympathetic outflow is increased but insufficient to compensate.
Capillary permeability is increased, not reduced, contributing to
relative hypovolemia.
Question 4
Which acid-base disturbance is most likely in a patient with chronic obstructive
pulmonary disease (COPD) and a compensatory increase in serum bicarbonate?
A. Acute respiratory alkalosis
B. Chronic respiratory acidosis
Page 3
