COMSAE-103B 2025 Simulated Exam: 100 High-Yield
USMLE/COMLEX-Style Questions with Answers and
Rationales – Basic Sciences, Clinical Medicine, and
Osteopathic Principles Review
Question 1
A 65-year-old man presents with sudden onset chest pain radiating to his
left arm. ECG shows ST-segment elevation in leads II, III, and aVF. Which
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: Inferior wall myocardial infarctions (ST elevation in II, III, aVF)
are typically due to right coronary artery occlusion.
Question 2
A 25-year-old woman presents with fatigue, pallor, and spoon-shaped
nails. Labs show microcytic anemia. Most likely diagnosis?
A) Vitamin B12 deficiency
B) Iron deficiency anemia
C) Sideroblastic anemia
D) Thalassemia
,Answer: B) Iron deficiency anemia
Rationale: Microcytic anemia with spoon-shaped nails is classic for
chronic iron deficiency.
Question 3
Which of the following is the primary neurotransmitter at the
neuromuscular junction?
A) Dopamine
B) Acetylcholine
C) GABA
D) Norepinephrine
Answer: B) Acetylcholine
Rationale: Acetylcholine binds nicotinic receptors on skeletal muscle to
cause contraction.
Question 4
A patient presents with severe right lower quadrant pain, nausea, and
anorexia. Ultrasound shows a non-compressible appendix. Next best
step?
A) CT abdomen
B) Start antibiotics only
C) Surgical consultation for appendectomy
D) Colonoscopy
Answer: C) Surgical consultation for appendectomy
Rationale: Acute appendicitis with supportive imaging requires prompt
surgical evaluation.
Question 5
Which of the following heart murmurs increases with inspiration?
A) Mitral regurgitation
,B) Tricuspid regurgitation
C) Aortic stenosis
D) Pulmonic stenosis
Answer: B) Tricuspid regurgitation
Rationale: Right-sided heart murmurs increase with inspiration due to
increased venous return.
Question 6
A 40-year-old woman has hyperpigmentation of her skin and hypotension.
Labs show hyponatremia and hyperkalemia. Most likely diagnosis?
A) Addison disease
B) Cushing syndrome
C) Hypothyroidism
D) Hyperaldosteronism
Answer: A) Addison disease
Rationale: Primary adrenal insufficiency causes low cortisol and
aldosterone → hyponatremia, hyperkalemia, hypotension, and
hyperpigmentation.
Question 7
Which bacterium is most commonly associated with peptic ulcer
disease?
A) Escherichia coli
B) Helicobacter pylori
C) Staphylococcus aureus
D) Streptococcus pyogenes
Answer: B) Helicobacter pylori
Rationale: H. pylori infection is the most common cause of gastric and
duodenal ulcers.Question 8
, A patient with COPD presents with worsening shortness of breath. Which
of the following physical exam findings is most consistent with
emphysema?
A) Barrel chest and decreased breath sounds
B) Inspiratory crackles at bases
C) Loud S3 heart sound
D) Peripheral edema
Answer: A) Barrel chest and decreased breath sounds
Rationale: Emphysema causes air trapping → barrel chest; breath sounds
are decreased due to alveolar destruction.
Question 9
A 7-year-old child presents with fever, sore throat, and a sandpaper-like
rash. Which complication is most concerning if untreated?
A) Rheumatic fever
B) Otitis media
C) Peritonsillar abscess
D) Scarlet fever
Answer: A) Rheumatic fever
Rationale: Group A Streptococcus infection (strep throat/scarlet fever)
can lead to rheumatic fever if untreated.
Question 10
Which of the following is the most common cause of hyperthyroidism?
A) Thyroid adenoma
B) Graves disease
USMLE/COMLEX-Style Questions with Answers and
Rationales – Basic Sciences, Clinical Medicine, and
Osteopathic Principles Review
Question 1
A 65-year-old man presents with sudden onset chest pain radiating to his
left arm. ECG shows ST-segment elevation in leads II, III, and aVF. Which
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: Inferior wall myocardial infarctions (ST elevation in II, III, aVF)
are typically due to right coronary artery occlusion.
Question 2
A 25-year-old woman presents with fatigue, pallor, and spoon-shaped
nails. Labs show microcytic anemia. Most likely diagnosis?
A) Vitamin B12 deficiency
B) Iron deficiency anemia
C) Sideroblastic anemia
D) Thalassemia
,Answer: B) Iron deficiency anemia
Rationale: Microcytic anemia with spoon-shaped nails is classic for
chronic iron deficiency.
Question 3
Which of the following is the primary neurotransmitter at the
neuromuscular junction?
A) Dopamine
B) Acetylcholine
C) GABA
D) Norepinephrine
Answer: B) Acetylcholine
Rationale: Acetylcholine binds nicotinic receptors on skeletal muscle to
cause contraction.
Question 4
A patient presents with severe right lower quadrant pain, nausea, and
anorexia. Ultrasound shows a non-compressible appendix. Next best
step?
A) CT abdomen
B) Start antibiotics only
C) Surgical consultation for appendectomy
D) Colonoscopy
Answer: C) Surgical consultation for appendectomy
Rationale: Acute appendicitis with supportive imaging requires prompt
surgical evaluation.
Question 5
Which of the following heart murmurs increases with inspiration?
A) Mitral regurgitation
,B) Tricuspid regurgitation
C) Aortic stenosis
D) Pulmonic stenosis
Answer: B) Tricuspid regurgitation
Rationale: Right-sided heart murmurs increase with inspiration due to
increased venous return.
Question 6
A 40-year-old woman has hyperpigmentation of her skin and hypotension.
Labs show hyponatremia and hyperkalemia. Most likely diagnosis?
A) Addison disease
B) Cushing syndrome
C) Hypothyroidism
D) Hyperaldosteronism
Answer: A) Addison disease
Rationale: Primary adrenal insufficiency causes low cortisol and
aldosterone → hyponatremia, hyperkalemia, hypotension, and
hyperpigmentation.
Question 7
Which bacterium is most commonly associated with peptic ulcer
disease?
A) Escherichia coli
B) Helicobacter pylori
C) Staphylococcus aureus
D) Streptococcus pyogenes
Answer: B) Helicobacter pylori
Rationale: H. pylori infection is the most common cause of gastric and
duodenal ulcers.Question 8
, A patient with COPD presents with worsening shortness of breath. Which
of the following physical exam findings is most consistent with
emphysema?
A) Barrel chest and decreased breath sounds
B) Inspiratory crackles at bases
C) Loud S3 heart sound
D) Peripheral edema
Answer: A) Barrel chest and decreased breath sounds
Rationale: Emphysema causes air trapping → barrel chest; breath sounds
are decreased due to alveolar destruction.
Question 9
A 7-year-old child presents with fever, sore throat, and a sandpaper-like
rash. Which complication is most concerning if untreated?
A) Rheumatic fever
B) Otitis media
C) Peritonsillar abscess
D) Scarlet fever
Answer: A) Rheumatic fever
Rationale: Group A Streptococcus infection (strep throat/scarlet fever)
can lead to rheumatic fever if untreated.
Question 10
Which of the following is the most common cause of hyperthyroidism?
A) Thyroid adenoma
B) Graves disease
