NBME Clinical Science Self-Assessment
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. A 55-year-old man presents with chest pain radiating to the left
arm. ECG shows ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending artery
B. Right coronary artery
C. Left circumflex artery
D. Posterior descending artery
Answer: B. Right coronary artery
Rationale: ST elevations in II, III, and aVF indicate an inferior
myocardial infarction. The right coronary artery commonly
supplies the inferior wall of the heart in most individuals.
Occlusion leads to inferior MI symptoms including bradycardia
and hypotension due to SA/AV node involvement.
,2. A 23-year-old woman presents with fatigue, pallor, and pica. Labs
show microcytic hypochromic anemia. Which is the most likely
cause?
A. Vitamin B12 deficiency
B. Iron deficiency anemia
C. Aplastic anemia
D. Hemolytic anemia
Answer: B. Iron deficiency anemia
Rationale: Microcytic hypochromic anemia with pica is classic for
iron deficiency. It is commonly caused by chronic blood loss (e.g.,
heavy menstruation) or dietary deficiency. B12 deficiency causes
macrocytic anemia.
3. A patient with COPD is given high-flow oxygen and subsequently
develops worsening hypercapnia. What is the primary
mechanism?
A. Haldane effect
B. Hypoxic respiratory drive suppression
C. Increased tidal volume
D. Pulmonary shunting
Answer: B. Hypoxic respiratory drive suppression
, Rationale: COPD patients may rely on hypoxic drive for
respiration. High oxygen levels can reduce respiratory drive,
leading to CO₂ retention and respiratory acidosis.
4. A 30-year-old man has episodic headaches, sweating, and
palpitations. Lab shows elevated metanephrines. Diagnosis?
A. Graves disease
B. Pheochromocytoma
C. Cushing syndrome
D. Hyperaldosteronism
Answer: B. Pheochromocytoma
Rationale: The classic triad of episodic headaches, sweating, and
palpitations with elevated catecholamine metabolites suggests
pheochromocytoma, a tumor of chromaffin cells.
5. Which enzyme is deficient in patients with Tay-Sachs disease?
A. Hexosaminidase A
B. Glucocerebrosidase
C. Sphingomyelinase
D. Galactocerebrosidase
Answer: A. Hexosaminidase A
, Rationale: Tay-Sachs disease is caused by deficiency of
hexosaminidase A, leading to GM2 ganglioside accumulation
and neurodegeneration.
6. A newborn has a “blueberry muffin” rash and
hepatosplenomegaly. Most likely cause?
A. CMV infection
B. Toxoplasmosis
C. Rubella
D. Syphilis
Answer: A. CMV infection
Rationale: Congenital CMV causes petechial rash (“blueberry
muffin”), hepatosplenomegaly, microcephaly, and periventricular
calcifications.
7. Which type of hypersensitivity is involved in hemolytic transfusion
reactions?
A. Type I
B. Type II
C. Type III
D. Type IV
Questions With Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. A 55-year-old man presents with chest pain radiating to the left
arm. ECG shows ST-segment elevation in leads II, III, and aVF.
Which coronary artery is most likely occluded?
A. Left anterior descending artery
B. Right coronary artery
C. Left circumflex artery
D. Posterior descending artery
Answer: B. Right coronary artery
Rationale: ST elevations in II, III, and aVF indicate an inferior
myocardial infarction. The right coronary artery commonly
supplies the inferior wall of the heart in most individuals.
Occlusion leads to inferior MI symptoms including bradycardia
and hypotension due to SA/AV node involvement.
,2. A 23-year-old woman presents with fatigue, pallor, and pica. Labs
show microcytic hypochromic anemia. Which is the most likely
cause?
A. Vitamin B12 deficiency
B. Iron deficiency anemia
C. Aplastic anemia
D. Hemolytic anemia
Answer: B. Iron deficiency anemia
Rationale: Microcytic hypochromic anemia with pica is classic for
iron deficiency. It is commonly caused by chronic blood loss (e.g.,
heavy menstruation) or dietary deficiency. B12 deficiency causes
macrocytic anemia.
3. A patient with COPD is given high-flow oxygen and subsequently
develops worsening hypercapnia. What is the primary
mechanism?
A. Haldane effect
B. Hypoxic respiratory drive suppression
C. Increased tidal volume
D. Pulmonary shunting
Answer: B. Hypoxic respiratory drive suppression
, Rationale: COPD patients may rely on hypoxic drive for
respiration. High oxygen levels can reduce respiratory drive,
leading to CO₂ retention and respiratory acidosis.
4. A 30-year-old man has episodic headaches, sweating, and
palpitations. Lab shows elevated metanephrines. Diagnosis?
A. Graves disease
B. Pheochromocytoma
C. Cushing syndrome
D. Hyperaldosteronism
Answer: B. Pheochromocytoma
Rationale: The classic triad of episodic headaches, sweating, and
palpitations with elevated catecholamine metabolites suggests
pheochromocytoma, a tumor of chromaffin cells.
5. Which enzyme is deficient in patients with Tay-Sachs disease?
A. Hexosaminidase A
B. Glucocerebrosidase
C. Sphingomyelinase
D. Galactocerebrosidase
Answer: A. Hexosaminidase A
, Rationale: Tay-Sachs disease is caused by deficiency of
hexosaminidase A, leading to GM2 ganglioside accumulation
and neurodegeneration.
6. A newborn has a “blueberry muffin” rash and
hepatosplenomegaly. Most likely cause?
A. CMV infection
B. Toxoplasmosis
C. Rubella
D. Syphilis
Answer: A. CMV infection
Rationale: Congenital CMV causes petechial rash (“blueberry
muffin”), hepatosplenomegaly, microcephaly, and periventricular
calcifications.
7. Which type of hypersensitivity is involved in hemolytic transfusion
reactions?
A. Type I
B. Type II
C. Type III
D. Type IV
