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COMSAE PHASE 1 PROFESSIONAL PRACTICE EXAM Questions with Detailed
Rationales UPDATED
Updated 2026/2027 Edition
Total Questions: 176
Sections: 4 × 44 Questions
Time Allowed: 4 hours (approx. 1 hour per section)
SECTION 1 (Questions 1–44)
Question 1
A 24-year-old woman presents with fever, sore throat, and
fatigue. Physical exam shows cervical lymphadenopathy and
splenomegaly. Blood smear reveals atypical lymphocytes.
Which virus is most likely responsible?
A. Cytomegalovirus
B. Epstein-Barr virus
C. HIV
D. Adenovirus
E. Human herpesvirus 6
Answer: B
Rationale: The classic triad of fever, pharyngitis, and
lymphadenopathy with atypical lymphocytes suggests
infectious mononucleosis caused by Epstein-Barr virus (EBV).
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Question 2
Which of the following is the primary inhibitory
neurotransmitter in the central nervous system?
A. Glutamate
B. Acetylcholine
C. GABA
D. Dopamine
E. Norepinephrine
Answer: C
Rationale: GABA (gamma-aminobutyric acid) is the main
inhibitory neurotransmitter in the CNS.
Question 3
A 58-year-old male presents with crushing chest pain,
diaphoresis, and ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending
B. Left circumflex
C. Right coronary artery
D. Left main
E. Posterior descending artery
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Answer: C
Rationale: ST elevation in inferior leads (II, III, aVF) indicates
inferior MI, usually due to right coronary artery occlusion.
Question 4
Which enzyme catalyzes the rate-limiting step of glycolysis?
A. Hexokinase
B. Phosphofructokinase-1
C. Pyruvate kinase
D. Aldolase
E. Glyceraldehyde-3-phosphate dehydrogenase
Answer: B
Rationale: Phosphofructokinase-1 (PFK-1) is the rate-limiting
enzyme of glycolysis and is allosterically regulated.
Question 5
A 45-year-old woman presents with progressive dysphagia to
solids and liquids, regurgitation, and a barium swallow showing
a "bird's beak" appearance. Which pathophysiologic mechanism
is most likely?
A. Fibrosis of esophageal submucosa
B. Loss of inhibitory myenteric plexus neurons
C. Malignant stricture
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D. Esophageal web
E. Hiatal hernia
Answer: B
Rationale: Achalasia is caused by loss of inhibitory neurons
(nitric oxide/VIP) in the myenteric plexus, leading to impaired
LES relaxation.
Question 6
Which of the following is a direct-acting sympathomimetic that
acts primarily on alpha-adrenergic receptors?
A. Epinephrine
B. Phenylephrine
C. Albuterol
D. Dobutamine
E. Terbutaline
Answer: B
Rationale: Phenylephrine is a selective alpha-1 agonist, causing
vasoconstriction.
Question 7
A 70-year-old woman with osteoporosis is prescribed
alendronate. Which of the following is a potential adverse
effect?
COMSAE PHASE 1 PROFESSIONAL PRACTICE EXAM Questions with Detailed
Rationales UPDATED
Updated 2026/2027 Edition
Total Questions: 176
Sections: 4 × 44 Questions
Time Allowed: 4 hours (approx. 1 hour per section)
SECTION 1 (Questions 1–44)
Question 1
A 24-year-old woman presents with fever, sore throat, and
fatigue. Physical exam shows cervical lymphadenopathy and
splenomegaly. Blood smear reveals atypical lymphocytes.
Which virus is most likely responsible?
A. Cytomegalovirus
B. Epstein-Barr virus
C. HIV
D. Adenovirus
E. Human herpesvirus 6
Answer: B
Rationale: The classic triad of fever, pharyngitis, and
lymphadenopathy with atypical lymphocytes suggests
infectious mononucleosis caused by Epstein-Barr virus (EBV).
, Page |2
Question 2
Which of the following is the primary inhibitory
neurotransmitter in the central nervous system?
A. Glutamate
B. Acetylcholine
C. GABA
D. Dopamine
E. Norepinephrine
Answer: C
Rationale: GABA (gamma-aminobutyric acid) is the main
inhibitory neurotransmitter in the CNS.
Question 3
A 58-year-old male presents with crushing chest pain,
diaphoresis, and ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending
B. Left circumflex
C. Right coronary artery
D. Left main
E. Posterior descending artery
, Page |3
Answer: C
Rationale: ST elevation in inferior leads (II, III, aVF) indicates
inferior MI, usually due to right coronary artery occlusion.
Question 4
Which enzyme catalyzes the rate-limiting step of glycolysis?
A. Hexokinase
B. Phosphofructokinase-1
C. Pyruvate kinase
D. Aldolase
E. Glyceraldehyde-3-phosphate dehydrogenase
Answer: B
Rationale: Phosphofructokinase-1 (PFK-1) is the rate-limiting
enzyme of glycolysis and is allosterically regulated.
Question 5
A 45-year-old woman presents with progressive dysphagia to
solids and liquids, regurgitation, and a barium swallow showing
a "bird's beak" appearance. Which pathophysiologic mechanism
is most likely?
A. Fibrosis of esophageal submucosa
B. Loss of inhibitory myenteric plexus neurons
C. Malignant stricture
, Page |4
D. Esophageal web
E. Hiatal hernia
Answer: B
Rationale: Achalasia is caused by loss of inhibitory neurons
(nitric oxide/VIP) in the myenteric plexus, leading to impaired
LES relaxation.
Question 6
Which of the following is a direct-acting sympathomimetic that
acts primarily on alpha-adrenergic receptors?
A. Epinephrine
B. Phenylephrine
C. Albuterol
D. Dobutamine
E. Terbutaline
Answer: B
Rationale: Phenylephrine is a selective alpha-1 agonist, causing
vasoconstriction.
Question 7
A 70-year-old woman with osteoporosis is prescribed
alendronate. Which of the following is a potential adverse
effect?
