COMSAE PHASE 1 ASA 114 REVIEW BOOK: 200+
NBOME-STYLE PRACTICE QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES |LATEST
UPDATE 2026
1. A 23-year-old woman presents with fatigue, dark urine, and jaundice 3 days
after beginning treatment with trimethoprim-sulfamethoxazole for a
urinary tract infection. She recently learned that several male relatives have
experienced similar episodes after taking certain medications. Which
enzyme deficiency most likely explains her symptoms?
A. Pyruvate kinase deficiency
B. Glucose-6-phosphate dehydrogenase deficiency
C. Hexokinase deficiency
D. Lactate dehydrogenase deficiency
Answer: B. Glucose-6-phosphate dehydrogenase deficiency
Rationale: G6PD deficiency reduces NADPH production, impairing glutathione
regeneration. Oxidative drugs such as sulfonamides can trigger hemolysis with
jaundice and dark urine.
2. A 61-year-old man develops crushing substernal chest pain lasting 2 hours.
Occlusion of the left anterior descending coronary artery is confirmed.
Which histologic change is expected within the first 12 hours?
A. Dense collagen deposition
B. Coagulative necrosis with early neutrophil infiltration
C. Granulation tissue formation
D. Extensive fibrosis
Answer: B. Coagulative necrosis with early neutrophil infiltration
,Rationale: During the first 4–24 hours after myocardial infarction, coagulative
necrosis develops with early neutrophilic infiltration.
3. A 6-year-old boy has recurrent respiratory infections and situs inversus.
Electron microscopy demonstrates absent dynein arms within cilia. Which
additional finding is most likely?
A. Hypercalcemia
B. Male infertility due to immotile sperm
C. Elevated uric acid
D. Cataracts
Answer: B. Male infertility due to immotile sperm
Rationale: Primary ciliary dyskinesia affects cilia and flagella, producing recurrent
infections, situs inversus, and infertility from impaired sperm motility.
4. A researcher administers a drug that selectively blocks voltage-gated
sodium channels in peripheral nerves. Which phase of the neuronal action
potential is directly inhibited?
A. Resting membrane potential
B. Rapid depolarization
C. Repolarization
D. Hyperpolarization
Answer: B. Rapid depolarization
Rationale: Opening of voltage-gated sodium channels is responsible for the rapid
upstroke of the action potential.
5. A patient with long-standing hypertension develops left ventricular
hypertrophy. Which cellular adaptation has occurred?
,A. Hyperplasia
B. Dysplasia
C. Hypertrophy
D. Metaplasia
Answer: C. Hypertrophy
Rationale: Cardiac myocytes respond to increased workload by increasing cell size
because they have limited regenerative capacity.
6. A newborn exhibits severe cyanosis immediately after birth.
Echocardiography reveals transposition of the great arteries. Which
embryologic structure failed to develop normally?
A. Septum primum
B. Neural crest-derived aorticopulmonary septum
C. Endocardial cushions
D. Sinus venosus
Answer: B. Neural crest-derived aorticopulmonary septum
Rationale: Abnormal spiraling of the neural crest-derived aorticopulmonary
septum produces transposition of the great arteries.
7. A patient receiving broad-spectrum antibiotics develops watery diarrhea.
Stool testing identifies a toxin-producing gram-positive anaerobic bacillus.
Which mechanism causes disease?
A. Increased cAMP only
B. Inactivation of elongation factor-2
C. Glucosylation of Rho GTPases leading to cytoskeletal disruption
D. Superantigen-mediated T-cell activation
Answer: C. Glucosylation of Rho GTPases leading to cytoskeletal disruption
, Rationale: Clostridioides difficile toxins A and B inactivate Rho proteins, causing
mucosal injury and pseudomembranous colitis.
8. A healthy individual begins strenuous exercise. Which metabolic pathway
primarily supplies ATP during the first few seconds?
A. Fatty acid oxidation
B. Glycolysis
C. Creatine phosphate system
D. Gluconeogenesis
Answer: C. Creatine phosphate system
Rationale: Stored creatine phosphate rapidly regenerates ATP during the initial
seconds of intense muscle contraction.
9. A patient has decreased vibration and proprioception below the waist after
spinal cord injury. Which tract is affected?
A. Spinothalamic tract
B. Lateral corticospinal tract
C. Dorsal columns
D. Spinocerebellar tract
Answer: C. Dorsal columns
Rationale: The dorsal columns transmit vibration, fine touch, and proprioception.
10.A woman develops flushing and hypotension minutes after receiving
penicillin. Which immunoglobulin mediates this reaction?
A. IgA
B. IgE
NBOME-STYLE PRACTICE QUESTIONS AND
VERIFIED ANSWERS WITH RATIONALES |LATEST
UPDATE 2026
1. A 23-year-old woman presents with fatigue, dark urine, and jaundice 3 days
after beginning treatment with trimethoprim-sulfamethoxazole for a
urinary tract infection. She recently learned that several male relatives have
experienced similar episodes after taking certain medications. Which
enzyme deficiency most likely explains her symptoms?
A. Pyruvate kinase deficiency
B. Glucose-6-phosphate dehydrogenase deficiency
C. Hexokinase deficiency
D. Lactate dehydrogenase deficiency
Answer: B. Glucose-6-phosphate dehydrogenase deficiency
Rationale: G6PD deficiency reduces NADPH production, impairing glutathione
regeneration. Oxidative drugs such as sulfonamides can trigger hemolysis with
jaundice and dark urine.
2. A 61-year-old man develops crushing substernal chest pain lasting 2 hours.
Occlusion of the left anterior descending coronary artery is confirmed.
Which histologic change is expected within the first 12 hours?
A. Dense collagen deposition
B. Coagulative necrosis with early neutrophil infiltration
C. Granulation tissue formation
D. Extensive fibrosis
Answer: B. Coagulative necrosis with early neutrophil infiltration
,Rationale: During the first 4–24 hours after myocardial infarction, coagulative
necrosis develops with early neutrophilic infiltration.
3. A 6-year-old boy has recurrent respiratory infections and situs inversus.
Electron microscopy demonstrates absent dynein arms within cilia. Which
additional finding is most likely?
A. Hypercalcemia
B. Male infertility due to immotile sperm
C. Elevated uric acid
D. Cataracts
Answer: B. Male infertility due to immotile sperm
Rationale: Primary ciliary dyskinesia affects cilia and flagella, producing recurrent
infections, situs inversus, and infertility from impaired sperm motility.
4. A researcher administers a drug that selectively blocks voltage-gated
sodium channels in peripheral nerves. Which phase of the neuronal action
potential is directly inhibited?
A. Resting membrane potential
B. Rapid depolarization
C. Repolarization
D. Hyperpolarization
Answer: B. Rapid depolarization
Rationale: Opening of voltage-gated sodium channels is responsible for the rapid
upstroke of the action potential.
5. A patient with long-standing hypertension develops left ventricular
hypertrophy. Which cellular adaptation has occurred?
,A. Hyperplasia
B. Dysplasia
C. Hypertrophy
D. Metaplasia
Answer: C. Hypertrophy
Rationale: Cardiac myocytes respond to increased workload by increasing cell size
because they have limited regenerative capacity.
6. A newborn exhibits severe cyanosis immediately after birth.
Echocardiography reveals transposition of the great arteries. Which
embryologic structure failed to develop normally?
A. Septum primum
B. Neural crest-derived aorticopulmonary septum
C. Endocardial cushions
D. Sinus venosus
Answer: B. Neural crest-derived aorticopulmonary septum
Rationale: Abnormal spiraling of the neural crest-derived aorticopulmonary
septum produces transposition of the great arteries.
7. A patient receiving broad-spectrum antibiotics develops watery diarrhea.
Stool testing identifies a toxin-producing gram-positive anaerobic bacillus.
Which mechanism causes disease?
A. Increased cAMP only
B. Inactivation of elongation factor-2
C. Glucosylation of Rho GTPases leading to cytoskeletal disruption
D. Superantigen-mediated T-cell activation
Answer: C. Glucosylation of Rho GTPases leading to cytoskeletal disruption
, Rationale: Clostridioides difficile toxins A and B inactivate Rho proteins, causing
mucosal injury and pseudomembranous colitis.
8. A healthy individual begins strenuous exercise. Which metabolic pathway
primarily supplies ATP during the first few seconds?
A. Fatty acid oxidation
B. Glycolysis
C. Creatine phosphate system
D. Gluconeogenesis
Answer: C. Creatine phosphate system
Rationale: Stored creatine phosphate rapidly regenerates ATP during the initial
seconds of intense muscle contraction.
9. A patient has decreased vibration and proprioception below the waist after
spinal cord injury. Which tract is affected?
A. Spinothalamic tract
B. Lateral corticospinal tract
C. Dorsal columns
D. Spinocerebellar tract
Answer: C. Dorsal columns
Rationale: The dorsal columns transmit vibration, fine touch, and proprioception.
10.A woman develops flushing and hypotension minutes after receiving
penicillin. Which immunoglobulin mediates this reaction?
A. IgA
B. IgE
