, Question 1
A cell exhibits defective ubiquitin-proteasome degradation of misfolded
proteins, leading to accumulation of ubiquitinated aggregates. Which
downstream consequence is the most direct molecular driver of this cell's
transition to a pro-apoptotic state?
A. Activation of the unfolded protein response via PERK-mediated eIF2
phosphorylation
B. Caspase-8 activation through death receptor oligomerization
C. Release of cytochrome c due to BAX/BAK pore formation in the
mitochondrial membrane
D. Depletion of ATP secondary to poly(ADP-ribose) polymerase
overactivation
Correct Answer: C - Release of cytochrome c due to BAX/BAK
pore formation in the mitochondrial membrane
RATIONALE
Proteasome inhibition causes ER stress and accumulation of misfolded
proteins, which triggers the intrinsic apoptotic pathway via BAX/BAK
mitochondrial outer membrane permeabilization and cytochrome c
release. This is the most direct downstream driver of apoptosis in this
context. Caspase-8 is extrinsic, UPR is an adaptive response, and
PARP overactivation is a consequence of DNA damage, not the
primary driver here.
Question 2
A patient with chronic kidney disease has an arterial blood gas showing pH
7.28, PaCO2 30 mmHg, HCO3- 14 mEq/L. Which compensatory mechanism
is primarily responsible for the respiratory finding?
A. Central chemoreceptor stimulation by decreased CSF pH
B. Peripheral chemoreceptor stimulation by hypoxemia
C. Direct stimulation of the medullary respiratory center by metabolic
acids
Page 2
, D. Compensatory hyperventilation driven by the peripheral
chemoreceptors responding to decreased arterial pH
Correct Answer: D - Compensatory hyperventilation driven by
the peripheral chemoreceptors responding to decreased arterial
pH
RATIONALE
In metabolic acidosis, the primary compensatory response is
hyperventilation (Kussmaul respirations) mediated by peripheral
chemoreceptors sensing decreased arterial pH. This lowers PaCO2 to
partially offset the metabolic acidosis. Central chemoreceptors
respond to CSF pH changes but are not the primary driver in acute
metabolic acidosis; hypoxemia is not the primary stimulus here.
Question 3
Which molecular alteration best explains the constitutive activation of the
JAK-STAT pathway in a myeloproliferative neoplasm?
A. BCR-ABL1 fusion gene
B. JAK2 V617F mutation
C. FLT3 internal tandem duplication
D. TP53 loss of function
Correct Answer: B - JAK2 V617F mutation
RATIONALE
The JAK2 V617F mutation is a common driver in myeloproliferative
neoplasms (e.g., polycythemia vera, essential thrombocythemia),
leading to constitutive JAK-STAT signaling. BCR-ABL1 is
characteristic of CML, FLT3-ITD in AML, and TP53 loss is seen in
various cancers but is not the primary driver of JAK-STAT activation.
Page 3
, Question 4
In a patient with septic shock, which pathophysiologic mechanism best
explains the observed hypotension refractory to fluid resuscitation?
A. Increased systemic vascular resistance due to sympathetic overdrive
B. Inducible nitric oxide synthase-mediated vasodilation and vascular
hyporesponsiveness to catecholamines
C. Cardiogenic depression from myocardial ischemia
D. Hypovolemia due to capillary leak
Correct Answer: B - Inducible nitric oxide synthase-mediated
vasodilation and vascular hyporesponsiveness to catecholamines
RATIONALE
Septic shock involves excessive nitric oxide production via iNOS,
leading to profound vasodilation and vascular hyporesponsiveness to
vasopressors. This explains fluid-refractory hypotension. Sympathetic
overdrive would increase SVR, cardiogenic depression is not the
primary mechanism, and hypovolemia is initially addressed by fluids
but is not the main cause of refractory hypotension.
Question 5
A patient with type 1 diabetes presents with deep, rapid breathing and fruity
breath. Which pathophysiologic process is the primary driver of this respiratory
pattern?
A. Respiratory compensation for metabolic alkalosis
B. Hyperventilation due to hypoxemia
C. Kussmaul respirations due to metabolic acidosis from ketone body
accumulation
D. Cheyne-Stokes respirations due to cerebral edema
Correct Answer: C - Kussmaul respirations due to metabolic
acidosis from ketone body accumulation
Page 4
A cell exhibits defective ubiquitin-proteasome degradation of misfolded
proteins, leading to accumulation of ubiquitinated aggregates. Which
downstream consequence is the most direct molecular driver of this cell's
transition to a pro-apoptotic state?
A. Activation of the unfolded protein response via PERK-mediated eIF2
phosphorylation
B. Caspase-8 activation through death receptor oligomerization
C. Release of cytochrome c due to BAX/BAK pore formation in the
mitochondrial membrane
D. Depletion of ATP secondary to poly(ADP-ribose) polymerase
overactivation
Correct Answer: C - Release of cytochrome c due to BAX/BAK
pore formation in the mitochondrial membrane
RATIONALE
Proteasome inhibition causes ER stress and accumulation of misfolded
proteins, which triggers the intrinsic apoptotic pathway via BAX/BAK
mitochondrial outer membrane permeabilization and cytochrome c
release. This is the most direct downstream driver of apoptosis in this
context. Caspase-8 is extrinsic, UPR is an adaptive response, and
PARP overactivation is a consequence of DNA damage, not the
primary driver here.
Question 2
A patient with chronic kidney disease has an arterial blood gas showing pH
7.28, PaCO2 30 mmHg, HCO3- 14 mEq/L. Which compensatory mechanism
is primarily responsible for the respiratory finding?
A. Central chemoreceptor stimulation by decreased CSF pH
B. Peripheral chemoreceptor stimulation by hypoxemia
C. Direct stimulation of the medullary respiratory center by metabolic
acids
Page 2
, D. Compensatory hyperventilation driven by the peripheral
chemoreceptors responding to decreased arterial pH
Correct Answer: D - Compensatory hyperventilation driven by
the peripheral chemoreceptors responding to decreased arterial
pH
RATIONALE
In metabolic acidosis, the primary compensatory response is
hyperventilation (Kussmaul respirations) mediated by peripheral
chemoreceptors sensing decreased arterial pH. This lowers PaCO2 to
partially offset the metabolic acidosis. Central chemoreceptors
respond to CSF pH changes but are not the primary driver in acute
metabolic acidosis; hypoxemia is not the primary stimulus here.
Question 3
Which molecular alteration best explains the constitutive activation of the
JAK-STAT pathway in a myeloproliferative neoplasm?
A. BCR-ABL1 fusion gene
B. JAK2 V617F mutation
C. FLT3 internal tandem duplication
D. TP53 loss of function
Correct Answer: B - JAK2 V617F mutation
RATIONALE
The JAK2 V617F mutation is a common driver in myeloproliferative
neoplasms (e.g., polycythemia vera, essential thrombocythemia),
leading to constitutive JAK-STAT signaling. BCR-ABL1 is
characteristic of CML, FLT3-ITD in AML, and TP53 loss is seen in
various cancers but is not the primary driver of JAK-STAT activation.
Page 3
, Question 4
In a patient with septic shock, which pathophysiologic mechanism best
explains the observed hypotension refractory to fluid resuscitation?
A. Increased systemic vascular resistance due to sympathetic overdrive
B. Inducible nitric oxide synthase-mediated vasodilation and vascular
hyporesponsiveness to catecholamines
C. Cardiogenic depression from myocardial ischemia
D. Hypovolemia due to capillary leak
Correct Answer: B - Inducible nitric oxide synthase-mediated
vasodilation and vascular hyporesponsiveness to catecholamines
RATIONALE
Septic shock involves excessive nitric oxide production via iNOS,
leading to profound vasodilation and vascular hyporesponsiveness to
vasopressors. This explains fluid-refractory hypotension. Sympathetic
overdrive would increase SVR, cardiogenic depression is not the
primary mechanism, and hypovolemia is initially addressed by fluids
but is not the main cause of refractory hypotension.
Question 5
A patient with type 1 diabetes presents with deep, rapid breathing and fruity
breath. Which pathophysiologic process is the primary driver of this respiratory
pattern?
A. Respiratory compensation for metabolic alkalosis
B. Hyperventilation due to hypoxemia
C. Kussmaul respirations due to metabolic acidosis from ketone body
accumulation
D. Cheyne-Stokes respirations due to cerebral edema
Correct Answer: C - Kussmaul respirations due to metabolic
acidosis from ketone body accumulation
Page 4
