100% Revised COMSAE Phase 1 Form
115 Practice Exam Questions And
Correct Answers (Verified Answers)
Plus Rationales 2025|2026 Q&A |
Instant Download Pdf
,1. A 45-year-old man presents with drooping of the right eyelid, constricted pupil,
and inability to sweat on the right side of the face. A chest X-ray reveals an apical
lung mass. Which nerve is most likely compressed by this tumor?
A. Phrenic nerve
B. Recurrent laryngeal nerve
C. Sympathetic chain
D. Vagus nerve
Correct ,,,,answer,,,,: C
Rationale: An apical lung mass (Pancoast tumor) compressing the cervical
sympathetic chain causes Horner syndrome (ptosis, miosis, anhidrosis).
2. Which of the following metabolic processes occurs in the mitochondrial matrix?
A. Glycolysis
B. Fatty acid synthesis
C. Tricarboxylic acid (TCA) cycle
D. Pentose phosphate pathway
Correct ,,,,answer,,,,: C
Rationale: The TCA cycle enzymes are located in the mitochondrial matrix, except
succinate dehydrogenase which is in the inner membrane.
3. A patient presents with bilateral loss of the temporal visual fields. A lesion is
most likely in which structure?
A. Optic nerve
B. Optic chiasm
,C. Optic tract
D. Occipital lobe
Correct ,,,,answer,,,,: B
Rationale: Bitemporal hemianopia results from compression of the decussating
fibers from the nasal retinas at the optic chiasm, commonly from a pituitary
adenoma.
4. Which enzyme is the rate-limiting step of cholesterol biosynthesis?
A. HMG-CoA synthase
B. HMG-CoA reductase
C. Acetyl-CoA carboxylase
D. Thiolase
Correct ,,,,answer,,,,: B
Rationale: HMG-CoA reductase catalyzes the conversion of HMG-CoA to
mevalonate, the primary regulatory step in cholesterol synthesis.
5. A Gram-positive coccus in clusters, coagulase-positive, is most likely:
A. Streptococcus pyogenes
B. Staphylococcus epidermidis
C. Staphylococcus aureus
D. Enterococcus faecalis
Correct ,,,,answer,,,,: C
Rationale: S. aureus is a coagulase-positive, Gram-positive coccus in clusters,
distinguished from coagulase-negative species like S. epidermidis.
, 6. In cardiac muscle, the plateau phase of the action potential is primarily due to:
A. Rapid sodium influx
B. Slow calcium influx and decreased potassium efflux
C. Chloride influx
D. Rapid potassium efflux
Correct ,,,,answer,,,,: B
Rationale: The plateau (phase 2) is maintained by L-type calcium channel influx
balanced by delayed rectifier potassium efflux, prolonging contraction.
7. A patient with chronic hypertension develops left ventricular hypertrophy. Which
of the following changes is seen in cardiac myocytes?
A. Hyperplasia
B. Atrophy
C. Hypertrophy
D. Metaplasia
Correct ,,,,answer,,,,: C
Rationale: Sustained pressure overload leads to hypertrophy (increase in cell size)
rather than hyperplasia.
8. Which of the following is a primary function of the peroxisome?
A. Protein synthesis
B. Oxidative phosphorylation
115 Practice Exam Questions And
Correct Answers (Verified Answers)
Plus Rationales 2025|2026 Q&A |
Instant Download Pdf
,1. A 45-year-old man presents with drooping of the right eyelid, constricted pupil,
and inability to sweat on the right side of the face. A chest X-ray reveals an apical
lung mass. Which nerve is most likely compressed by this tumor?
A. Phrenic nerve
B. Recurrent laryngeal nerve
C. Sympathetic chain
D. Vagus nerve
Correct ,,,,answer,,,,: C
Rationale: An apical lung mass (Pancoast tumor) compressing the cervical
sympathetic chain causes Horner syndrome (ptosis, miosis, anhidrosis).
2. Which of the following metabolic processes occurs in the mitochondrial matrix?
A. Glycolysis
B. Fatty acid synthesis
C. Tricarboxylic acid (TCA) cycle
D. Pentose phosphate pathway
Correct ,,,,answer,,,,: C
Rationale: The TCA cycle enzymes are located in the mitochondrial matrix, except
succinate dehydrogenase which is in the inner membrane.
3. A patient presents with bilateral loss of the temporal visual fields. A lesion is
most likely in which structure?
A. Optic nerve
B. Optic chiasm
,C. Optic tract
D. Occipital lobe
Correct ,,,,answer,,,,: B
Rationale: Bitemporal hemianopia results from compression of the decussating
fibers from the nasal retinas at the optic chiasm, commonly from a pituitary
adenoma.
4. Which enzyme is the rate-limiting step of cholesterol biosynthesis?
A. HMG-CoA synthase
B. HMG-CoA reductase
C. Acetyl-CoA carboxylase
D. Thiolase
Correct ,,,,answer,,,,: B
Rationale: HMG-CoA reductase catalyzes the conversion of HMG-CoA to
mevalonate, the primary regulatory step in cholesterol synthesis.
5. A Gram-positive coccus in clusters, coagulase-positive, is most likely:
A. Streptococcus pyogenes
B. Staphylococcus epidermidis
C. Staphylococcus aureus
D. Enterococcus faecalis
Correct ,,,,answer,,,,: C
Rationale: S. aureus is a coagulase-positive, Gram-positive coccus in clusters,
distinguished from coagulase-negative species like S. epidermidis.
, 6. In cardiac muscle, the plateau phase of the action potential is primarily due to:
A. Rapid sodium influx
B. Slow calcium influx and decreased potassium efflux
C. Chloride influx
D. Rapid potassium efflux
Correct ,,,,answer,,,,: B
Rationale: The plateau (phase 2) is maintained by L-type calcium channel influx
balanced by delayed rectifier potassium efflux, prolonging contraction.
7. A patient with chronic hypertension develops left ventricular hypertrophy. Which
of the following changes is seen in cardiac myocytes?
A. Hyperplasia
B. Atrophy
C. Hypertrophy
D. Metaplasia
Correct ,,,,answer,,,,: C
Rationale: Sustained pressure overload leads to hypertrophy (increase in cell size)
rather than hyperplasia.
8. Which of the following is a primary function of the peroxisome?
A. Protein synthesis
B. Oxidative phosphorylation
