COMSAE PHASE 1 ASA 116 COMPREHENSIVE PRACTICE
EXAMINATION QUESTIONS AND ANSWERS WITH
RATIONALES|A+ GUARANTEED
1. A 24-year-old woman presents with fatigue and recurrent bacterial
infections. Flow cytometry demonstrates absent CD19-positive cells. Which
immune defect best explains her condition?
A. Defective T-cell maturation
B. Absence of B-cell differentiation
C. Defective neutrophil oxidative burst
D. C5-C9 complement deficiency
E. Impaired MHC II expression
Answer: B
Rationale: CD19 is a B-cell marker. Absent CD19-positive cells indicate failure of B-
cell maturation, resulting in antibody deficiency and recurrent bacterial infections.
2. A patient develops severe hypotension immediately after a bee sting. Which
mediator is primarily responsible for the rapid vasodilation?
A. Leukotriene B4
B. Interleukin-2
C. Histamine
D. Interferon-γ
E. TNF-α
Rationale: Histamine released from mast cells causes rapid vasodilation and
increased vascular permeability during anaphylaxis.
, 3. A mutation causes inability of the Na⁺/K⁺-ATPase pump to function. Which
immediate intracellular change occurs?
A. Increased intracellular potassium
B. Increased extracellular sodium
C. Increased intracellular sodium
D. Increased membrane hyperpolarization
E. Increased calcium export
Rationale: Failure of the sodium-potassium pump allows sodium to accumulate
within cells.
4. Which cranial nerve carries parasympathetic fibers to the parotid gland?
A. Facial nerve
B. Vagus nerve
C. Glossopharyngeal nerve
D. Trigeminal nerve
E. Hypoglossal nerve
Answer: C
Rationale: Parasympathetic fibers originate in CN IX, travel through the lesser
petrosal nerve and otic ganglion before reaching the parotid gland.
5. A patient has elevated PTH, elevated calcium, decreased phosphate, and
increased urinary cAMP. Which diagnosis is most likely?
A. Vitamin D deficiency
B. Chronic kidney disease
C. Secondary hyperparathyroidism
D. Primary hyperparathyroidism
E. Hypoparathyroidism
,Rationale: Primary hyperparathyroidism produces hypercalcemia,
hypophosphatemia, elevated PTH, and increased urinary cAMP.
6. The mechanism of action of aspirin is:
A. Reversible COX inhibition
B. Lipoxygenase inhibition
C. PDE inhibition
D. Irreversible COX-1 and COX-2 inhibition
E. ADP receptor blockade
Rationale: Aspirin irreversibly acetylates cyclooxygenase enzymes, decreasing
prostaglandin and thromboxane synthesis.
7. A patient has ST elevation in leads II, III, and aVF. Which artery is most likely
occluded?
A. Left anterior descending artery
B. Circumflex artery
C. Left main coronary artery
D. Right coronary artery
E. Diagonal branch
Rationale: Inferior myocardial infarctions most commonly involve the right
coronary artery.
8. A child presents with recurrent catalase-positive infections. Which enzyme
is deficient?
A. Myeloperoxidase
B. NADPH oxidase
C. Glucose-6-phosphatase
, D. Superoxide dismutase
E. Catalase
Rationale: Chronic granulomatous disease results from NADPH oxidase deficiency.
9. Which organism is the most common cause of community-acquired atypical
pneumonia in young adults?
A. Streptococcus pneumoniae
B. Klebsiella pneumoniae
C. Mycoplasma pneumoniae
D. Haemophilus influenzae
E. Legionella pneumophila
Rationale: Mycoplasma causes atypical pneumonia with a gradual onset and
diffuse interstitial infiltrates.
10.A patient has right sacral torsion on a right oblique axis. During diagnosis,
the seated flexion test is expected to be positive on the:
A. Left
B. Right
C. Bilateral
D. Neither side
E. Alternating sides
Rationale: In a right-on-right sacral torsion, the seated flexion test is typically
positive on the right.
11.A patient with uncontrolled diabetes develops ketoacidosis. Which enzyme
is activated by glucagon to promote ketogenesis?
A. Acetyl-CoA carboxylase
B. Pyruvate kinase
EXAMINATION QUESTIONS AND ANSWERS WITH
RATIONALES|A+ GUARANTEED
1. A 24-year-old woman presents with fatigue and recurrent bacterial
infections. Flow cytometry demonstrates absent CD19-positive cells. Which
immune defect best explains her condition?
A. Defective T-cell maturation
B. Absence of B-cell differentiation
C. Defective neutrophil oxidative burst
D. C5-C9 complement deficiency
E. Impaired MHC II expression
Answer: B
Rationale: CD19 is a B-cell marker. Absent CD19-positive cells indicate failure of B-
cell maturation, resulting in antibody deficiency and recurrent bacterial infections.
2. A patient develops severe hypotension immediately after a bee sting. Which
mediator is primarily responsible for the rapid vasodilation?
A. Leukotriene B4
B. Interleukin-2
C. Histamine
D. Interferon-γ
E. TNF-α
Rationale: Histamine released from mast cells causes rapid vasodilation and
increased vascular permeability during anaphylaxis.
, 3. A mutation causes inability of the Na⁺/K⁺-ATPase pump to function. Which
immediate intracellular change occurs?
A. Increased intracellular potassium
B. Increased extracellular sodium
C. Increased intracellular sodium
D. Increased membrane hyperpolarization
E. Increased calcium export
Rationale: Failure of the sodium-potassium pump allows sodium to accumulate
within cells.
4. Which cranial nerve carries parasympathetic fibers to the parotid gland?
A. Facial nerve
B. Vagus nerve
C. Glossopharyngeal nerve
D. Trigeminal nerve
E. Hypoglossal nerve
Answer: C
Rationale: Parasympathetic fibers originate in CN IX, travel through the lesser
petrosal nerve and otic ganglion before reaching the parotid gland.
5. A patient has elevated PTH, elevated calcium, decreased phosphate, and
increased urinary cAMP. Which diagnosis is most likely?
A. Vitamin D deficiency
B. Chronic kidney disease
C. Secondary hyperparathyroidism
D. Primary hyperparathyroidism
E. Hypoparathyroidism
,Rationale: Primary hyperparathyroidism produces hypercalcemia,
hypophosphatemia, elevated PTH, and increased urinary cAMP.
6. The mechanism of action of aspirin is:
A. Reversible COX inhibition
B. Lipoxygenase inhibition
C. PDE inhibition
D. Irreversible COX-1 and COX-2 inhibition
E. ADP receptor blockade
Rationale: Aspirin irreversibly acetylates cyclooxygenase enzymes, decreasing
prostaglandin and thromboxane synthesis.
7. A patient has ST elevation in leads II, III, and aVF. Which artery is most likely
occluded?
A. Left anterior descending artery
B. Circumflex artery
C. Left main coronary artery
D. Right coronary artery
E. Diagonal branch
Rationale: Inferior myocardial infarctions most commonly involve the right
coronary artery.
8. A child presents with recurrent catalase-positive infections. Which enzyme
is deficient?
A. Myeloperoxidase
B. NADPH oxidase
C. Glucose-6-phosphatase
, D. Superoxide dismutase
E. Catalase
Rationale: Chronic granulomatous disease results from NADPH oxidase deficiency.
9. Which organism is the most common cause of community-acquired atypical
pneumonia in young adults?
A. Streptococcus pneumoniae
B. Klebsiella pneumoniae
C. Mycoplasma pneumoniae
D. Haemophilus influenzae
E. Legionella pneumophila
Rationale: Mycoplasma causes atypical pneumonia with a gradual onset and
diffuse interstitial infiltrates.
10.A patient has right sacral torsion on a right oblique axis. During diagnosis,
the seated flexion test is expected to be positive on the:
A. Left
B. Right
C. Bilateral
D. Neither side
E. Alternating sides
Rationale: In a right-on-right sacral torsion, the seated flexion test is typically
positive on the right.
11.A patient with uncontrolled diabetes develops ketoacidosis. Which enzyme
is activated by glucagon to promote ketogenesis?
A. Acetyl-CoA carboxylase
B. Pyruvate kinase
