COMSAE Phase 1 Form E Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. A 23-year-old man presents with fatigue, pallor, and glossitis.
Laboratory studies show macrocytic anemia with hypersegmented
neutrophils. Which vitamin deficiency is most likely?
A. Vitamin B1
B. Vitamin B6
C. Vitamin B9
D. Vitamin C
Correct Answer: C. Vitamin B9
Rationale: Vitamin B9 (folate) deficiency causes megaloblastic anemia
characterized by macrocytosis and hypersegmented neutrophils.
Folate is required for DNA synthesis, and deficiency impairs rapidly
dividing cells such as those in bone marrow.
2. A patient has a lesion affecting the left optic tract. What visual
field defect is expected?
, A. Left monocular blindness
B. Right monocular blindness
C. Right homonymous hemianopia
D. Left bitemporal hemianopia
Correct Answer: C. Right homonymous hemianopia
Rationale: The optic tract carries visual information from the
contralateral visual field. A left optic tract lesion results in loss of the
right visual field in both eyes.
3. Which structure is primarily responsible for producing
cerebrospinal fluid?
A. Arachnoid villi
B. Choroid plexus
C. Dura mater
D. Pineal gland
Correct Answer: B. Choroid plexus
Rationale: The choroid plexus, located in the ventricles, produces
cerebrospinal fluid through ependymal cells.
, 4. A 65-year-old man has resting tremor, rigidity, and bradykinesia.
Which brain structure is most affected?
A. Caudate nucleus
B. Substantia nigra
C. Hippocampus
D. Cerebellar vermis
Correct Answer: B. Substantia nigra
Rationale: Parkinson disease is due to degeneration of dopaminergic
neurons in the substantia nigra pars compacta.
5. Which ion is primarily responsible for the plateau phase of the
cardiac action potential?
A. Sodium
B. Potassium
C. Calcium
D. Chloride
Correct Answer: C. Calcium
Rationale: The plateau phase (phase 2) is maintained by calcium influx
through L-type calcium channels balancing potassium efflux.
, 6. A child presents with vesicular rash starting on the trunk and
spreading outward. What is the most likely virus?
A. Measles virus
B. Varicella-zoster virus
C. Rubella virus
D. Parvovirus B19
Correct Answer: B. Varicella-zoster virus
Rationale: Varicella (chickenpox) classically presents with a centripetal
vesicular rash beginning on the trunk.
7. Which kidney structure is responsible for concentrating urine?
A. Glomerulus
B. Proximal tubule
C. Loop of Henle
D. Bowman's capsule
Correct Answer: C. Loop of Henle
Rationale: The loop of Henle establishes a countercurrent multiplier
system essential for urine concentration.
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. A 23-year-old man presents with fatigue, pallor, and glossitis.
Laboratory studies show macrocytic anemia with hypersegmented
neutrophils. Which vitamin deficiency is most likely?
A. Vitamin B1
B. Vitamin B6
C. Vitamin B9
D. Vitamin C
Correct Answer: C. Vitamin B9
Rationale: Vitamin B9 (folate) deficiency causes megaloblastic anemia
characterized by macrocytosis and hypersegmented neutrophils.
Folate is required for DNA synthesis, and deficiency impairs rapidly
dividing cells such as those in bone marrow.
2. A patient has a lesion affecting the left optic tract. What visual
field defect is expected?
, A. Left monocular blindness
B. Right monocular blindness
C. Right homonymous hemianopia
D. Left bitemporal hemianopia
Correct Answer: C. Right homonymous hemianopia
Rationale: The optic tract carries visual information from the
contralateral visual field. A left optic tract lesion results in loss of the
right visual field in both eyes.
3. Which structure is primarily responsible for producing
cerebrospinal fluid?
A. Arachnoid villi
B. Choroid plexus
C. Dura mater
D. Pineal gland
Correct Answer: B. Choroid plexus
Rationale: The choroid plexus, located in the ventricles, produces
cerebrospinal fluid through ependymal cells.
, 4. A 65-year-old man has resting tremor, rigidity, and bradykinesia.
Which brain structure is most affected?
A. Caudate nucleus
B. Substantia nigra
C. Hippocampus
D. Cerebellar vermis
Correct Answer: B. Substantia nigra
Rationale: Parkinson disease is due to degeneration of dopaminergic
neurons in the substantia nigra pars compacta.
5. Which ion is primarily responsible for the plateau phase of the
cardiac action potential?
A. Sodium
B. Potassium
C. Calcium
D. Chloride
Correct Answer: C. Calcium
Rationale: The plateau phase (phase 2) is maintained by calcium influx
through L-type calcium channels balancing potassium efflux.
, 6. A child presents with vesicular rash starting on the trunk and
spreading outward. What is the most likely virus?
A. Measles virus
B. Varicella-zoster virus
C. Rubella virus
D. Parvovirus B19
Correct Answer: B. Varicella-zoster virus
Rationale: Varicella (chickenpox) classically presents with a centripetal
vesicular rash beginning on the trunk.
7. Which kidney structure is responsible for concentrating urine?
A. Glomerulus
B. Proximal tubule
C. Loop of Henle
D. Bowman's capsule
Correct Answer: C. Loop of Henle
Rationale: The loop of Henle establishes a countercurrent multiplier
system essential for urine concentration.
