COMSAE Phase 1 / COMLEX Level 1 Practice
Questions (60–100) with Verified Answers and
Detailed Rationales 2025–2026 | High-Yield Exam
Prep
Q1.
A 22-year-old presents with fatigue and paresthesias. Labs show macrocytic anemia and
increased methylmalonic acid. Which deficiency is most likely?
A. Folate
B. Iron
C. Vitamin B12
D. Vitamin B6
Answer: C. Vitamin B12
Rationale: Vitamin B12 deficiency causes megaloblastic anemia plus neurologic
symptoms and elevated methylmalonic acid and homocysteine.
Q2.
Which organ is primarily responsible for gluconeogenesis during prolonged fasting?
A. Brain
B. Liver
C. Muscle
D. Adipose tissue
Answer: B. Liver
Rationale: The liver is the main site of gluconeogenesis; the kidney contributes during
prolonged fasting.
Q3.
A patient has decreased preload. Which heart sound is most affected?
A. S1
,B. S2
C. S3
D. S4
Answer: C. S3
Rationale: S3 is associated with volume overload and increased ventricular filling; reduced
preload decreases S3.
Q4.
Which antibiotic inhibits bacterial cell wall synthesis by binding PBPs?
A. Tetracycline
B. Penicillin
C. Ciprofloxacin
D. Erythromycin
Answer: B. Penicillin
Rationale: Beta-lactams bind penicillin-binding proteins and inhibit peptidoglycan cross-
linking.
Q5.
A lesion of the left oculomotor nerve would cause:
A. Ptosis and down-and-out eye
B. Loss of facial sensation
C. Hearing loss
D. Tongue deviation to left
Answer: A. Ptosis and down-and-out eye
Rationale: CN III palsy causes unopposed action of lateral rectus and superior oblique
muscles.
Q6.
Which hypersensitivity reaction is Type I?
A. Immune complex deposition
,B. IgE-mediated reaction
C. Cytotoxic T-cell response
D. Complement activation only
Answer: B. IgE-mediated reaction
Rationale: Type I hypersensitivity involves IgE and mast cell degranulation (e.g.,
anaphylaxis, asthma).
Q7.
Which condition is associated with increased HbA1c levels?
A. Acute blood loss
B. Iron deficiency anemia
C. Hemolytic anemia
D. Chronic renal failure
Answer: B. Iron deficiency anemia
Rationale: Iron deficiency can falsely elevate HbA1c due to prolonged RBC lifespan.
Q8.
Which hormone increases serum calcium?
A. Calcitonin
B. Parathyroid hormone
C. Insulin
D. Aldosterone
Answer: B. Parathyroid hormone
Rationale: PTH increases calcium via bone resorption, renal reabsorption, and vitamin D
activation.
Q9.
Which structure connects the right and left cerebral hemispheres?
A. Internal capsule
B. Corpus callosum
, C. Thalamus
D. Basal ganglia
Answer: B. Corpus callosum
Rationale: The corpus callosum is the major commissural fiber tract between
hemispheres.
Q10.
A patient has watery diarrhea after antibiotic use. Which organism is most likely?
A. E. Coli
B. Clostridioides difficile
C. Salmonella typhi
D. Shigella dysenteriae
Answer: B. Clostridioides difficile
Rationale: C. Difficile produces toxins causing pseudomembranous colitis after
antibiotics.
Q11.
Which acid-base disorder is seen in uncontrolled diabetes mellitus?
A. Respiratory alkalosis
B. Metabolic alkalosis
C. Metabolic acidosis with anion gap
D. Respiratory acidosis
Answer: C. Metabolic acidosis with anion gap
Rationale: Diabetic ketoacidosis produces ketoacids leading to high anion gap metabolic
acidosis.
Q12.
Which vitamin is required for gamma-carboxylation of clotting factors?
A. Vitamin C
B. Vitamin D
Questions (60–100) with Verified Answers and
Detailed Rationales 2025–2026 | High-Yield Exam
Prep
Q1.
A 22-year-old presents with fatigue and paresthesias. Labs show macrocytic anemia and
increased methylmalonic acid. Which deficiency is most likely?
A. Folate
B. Iron
C. Vitamin B12
D. Vitamin B6
Answer: C. Vitamin B12
Rationale: Vitamin B12 deficiency causes megaloblastic anemia plus neurologic
symptoms and elevated methylmalonic acid and homocysteine.
Q2.
Which organ is primarily responsible for gluconeogenesis during prolonged fasting?
A. Brain
B. Liver
C. Muscle
D. Adipose tissue
Answer: B. Liver
Rationale: The liver is the main site of gluconeogenesis; the kidney contributes during
prolonged fasting.
Q3.
A patient has decreased preload. Which heart sound is most affected?
A. S1
,B. S2
C. S3
D. S4
Answer: C. S3
Rationale: S3 is associated with volume overload and increased ventricular filling; reduced
preload decreases S3.
Q4.
Which antibiotic inhibits bacterial cell wall synthesis by binding PBPs?
A. Tetracycline
B. Penicillin
C. Ciprofloxacin
D. Erythromycin
Answer: B. Penicillin
Rationale: Beta-lactams bind penicillin-binding proteins and inhibit peptidoglycan cross-
linking.
Q5.
A lesion of the left oculomotor nerve would cause:
A. Ptosis and down-and-out eye
B. Loss of facial sensation
C. Hearing loss
D. Tongue deviation to left
Answer: A. Ptosis and down-and-out eye
Rationale: CN III palsy causes unopposed action of lateral rectus and superior oblique
muscles.
Q6.
Which hypersensitivity reaction is Type I?
A. Immune complex deposition
,B. IgE-mediated reaction
C. Cytotoxic T-cell response
D. Complement activation only
Answer: B. IgE-mediated reaction
Rationale: Type I hypersensitivity involves IgE and mast cell degranulation (e.g.,
anaphylaxis, asthma).
Q7.
Which condition is associated with increased HbA1c levels?
A. Acute blood loss
B. Iron deficiency anemia
C. Hemolytic anemia
D. Chronic renal failure
Answer: B. Iron deficiency anemia
Rationale: Iron deficiency can falsely elevate HbA1c due to prolonged RBC lifespan.
Q8.
Which hormone increases serum calcium?
A. Calcitonin
B. Parathyroid hormone
C. Insulin
D. Aldosterone
Answer: B. Parathyroid hormone
Rationale: PTH increases calcium via bone resorption, renal reabsorption, and vitamin D
activation.
Q9.
Which structure connects the right and left cerebral hemispheres?
A. Internal capsule
B. Corpus callosum
, C. Thalamus
D. Basal ganglia
Answer: B. Corpus callosum
Rationale: The corpus callosum is the major commissural fiber tract between
hemispheres.
Q10.
A patient has watery diarrhea after antibiotic use. Which organism is most likely?
A. E. Coli
B. Clostridioides difficile
C. Salmonella typhi
D. Shigella dysenteriae
Answer: B. Clostridioides difficile
Rationale: C. Difficile produces toxins causing pseudomembranous colitis after
antibiotics.
Q11.
Which acid-base disorder is seen in uncontrolled diabetes mellitus?
A. Respiratory alkalosis
B. Metabolic alkalosis
C. Metabolic acidosis with anion gap
D. Respiratory acidosis
Answer: C. Metabolic acidosis with anion gap
Rationale: Diabetic ketoacidosis produces ketoacids leading to high anion gap metabolic
acidosis.
Q12.
Which vitamin is required for gamma-carboxylation of clotting factors?
A. Vitamin C
B. Vitamin D
