COMSAE Phase 1 Form 115 Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1
A 45-year-old man presents with crushing substernal chest pain
radiating to his left arm. ECG shows ST elevation in leads II, III, and aVF.
Which artery is most likely occluded?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Posterior descending artery
Answer: C. Right coronary artery
Rationale: Inferior wall MI (II, III, aVF) is most commonly due to right
coronary artery occlusion, which supplies the inferior portion of the
left ventricle in most patients.
2
,Which embryologic structure gives rise to the thyroid C cells?
A. Pharyngeal pouch 1
B. Pharyngeal pouch 2
C. Pharyngeal pouch 3
D. Pharyngeal pouch 4
Answer: D. Pharyngeal pouch 4
Rationale: Parafollicular (C) cells originate from the ultimobranchial
body derived from the fourth pharyngeal pouch.
3
A patient has prolonged PT and normal PTT. Which factor is most likely
deficient?
A. Factor VIII
B. Factor IX
C. Factor VII
D. Factor X
Answer: C. Factor VII
Rationale: Factor VII is part of the extrinsic pathway and affects PT
only due to its short half-life.
,4
Which structure is most responsible for lowering intracellular cAMP in
cardiac myocytes?
A. Beta-1 receptor
B. Alpha-1 receptor
C. Beta-2 receptor
D. Muscarinic M2 receptor
Answer: D. Muscarinic M2 receptor
Rationale: M2 receptors activate Gi proteins, decreasing cAMP and
reducing heart rate and contractility.
5
A newborn fails to pass meconium and has a distended abdomen.
Biopsy shows absence of ganglion cells. Diagnosis?
A. Meckel diverticulum
B. Hirschsprung disease
C. Pyloric stenosis
D. Intussusception
, Answer: B. Hirschsprung disease
Rationale: Failure of neural crest cell migration leads to aganglionic
megacolon.
6
Which acid-base disorder is characterized by increased anion gap
metabolic acidosis?
A. Vomiting
B. Diarrhea
C. Lactic acidosis
D. Hyperaldosteronism
Answer: C. Lactic acidosis
Rationale: Lactic acid accumulation increases unmeasured anions,
raising the anion gap.
7
Which drug is a competitive inhibitor of HMG-CoA reductase?
A. Ezetimibe
B. Niacin
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1
A 45-year-old man presents with crushing substernal chest pain
radiating to his left arm. ECG shows ST elevation in leads II, III, and aVF.
Which artery is most likely occluded?
A. Left anterior descending artery
B. Left circumflex artery
C. Right coronary artery
D. Posterior descending artery
Answer: C. Right coronary artery
Rationale: Inferior wall MI (II, III, aVF) is most commonly due to right
coronary artery occlusion, which supplies the inferior portion of the
left ventricle in most patients.
2
,Which embryologic structure gives rise to the thyroid C cells?
A. Pharyngeal pouch 1
B. Pharyngeal pouch 2
C. Pharyngeal pouch 3
D. Pharyngeal pouch 4
Answer: D. Pharyngeal pouch 4
Rationale: Parafollicular (C) cells originate from the ultimobranchial
body derived from the fourth pharyngeal pouch.
3
A patient has prolonged PT and normal PTT. Which factor is most likely
deficient?
A. Factor VIII
B. Factor IX
C. Factor VII
D. Factor X
Answer: C. Factor VII
Rationale: Factor VII is part of the extrinsic pathway and affects PT
only due to its short half-life.
,4
Which structure is most responsible for lowering intracellular cAMP in
cardiac myocytes?
A. Beta-1 receptor
B. Alpha-1 receptor
C. Beta-2 receptor
D. Muscarinic M2 receptor
Answer: D. Muscarinic M2 receptor
Rationale: M2 receptors activate Gi proteins, decreasing cAMP and
reducing heart rate and contractility.
5
A newborn fails to pass meconium and has a distended abdomen.
Biopsy shows absence of ganglion cells. Diagnosis?
A. Meckel diverticulum
B. Hirschsprung disease
C. Pyloric stenosis
D. Intussusception
, Answer: B. Hirschsprung disease
Rationale: Failure of neural crest cell migration leads to aganglionic
megacolon.
6
Which acid-base disorder is characterized by increased anion gap
metabolic acidosis?
A. Vomiting
B. Diarrhea
C. Lactic acidosis
D. Hyperaldosteronism
Answer: C. Lactic acidosis
Rationale: Lactic acid accumulation increases unmeasured anions,
raising the anion gap.
7
Which drug is a competitive inhibitor of HMG-CoA reductase?
A. Ezetimibe
B. Niacin
