COMSAE Phase 1 Form 113 Practice
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales
2026|2027 Q&A | Instant Download
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1. The motor cortex responsible for voluntary movement is
located in which gyrus?
A. Superior temporal gyrus
B. Precentral gyrus
C. Postcentral gyrus
D. Precentral gyrus
Rationale: The primary motor cortex is located in the precentral
gyrus of the frontal lobe and controls voluntary movement.
2. Which amino acid is essential and a precursor for nitric oxide
synthesis?
A. Lysine
B. Arginine
,C. Glycine
D. Glutamine
Rationale: Arginine is the substrate for nitric oxide synthase,
producing nitric oxide.
3. Which heart valve prevents backflow from the left ventricle
into the left atrium?
A. Pulmonary valve
B. Tricuspid valve
C. Mitral (bicuspid) valve
D. Aortic valve
Rationale: The mitral valve (bicuspid) is between the left
atrium and left ventricle and prevents regurgitation during
systole.
4. A Gram-positive, catalase-positive cocci in clusters is most
likely:
A. Streptococcus pyogenes
B. Staphylococcus aureus
C. Enterococcus faecalis
D. Neisseria gonorrhoeae
Rationale: Staphylococci are Gram-positive cocci in clusters
and are catalase-positive; S. aureus is a common example.
,5. Which structure of the nephron is primarily responsible for
filtration?
A. Proximal tubule
B. Loop of Henle
C. Distal tubule
D. Glomerulus (Bowman capsule)
Rationale: Filtration of plasma into Bowman’s space occurs at
the glomerulus within Bowman capsule.
6. In glycolysis, the rate-limiting enzyme that converts fructose-
6-phosphate to fructose-1,6-bisphosphate is:
A. Hexokinase
B. Pyruvate kinase
C. Phosphofructokinase-1 (PFK-1)
D. Aldolase
Rationale: PFK-1 is the major regulatory, rate-limiting enzyme
of glycolysis.
7. The alveolar gas equation estimates alveolar O₂ tension.
Which variable is directly subtracted from inspired O₂ partial
pressure in the simplified alveolar gas equation?
A. PaCO₂/R (where R is respiratory quotient)
B. PaCO₂/R
, C. Water vapor pressure
D. Hemoglobin concentration
Rationale: The simplified alveolar gas equation subtracts
PaCO₂ divided by the respiratory quotient from inspired O₂
partial pressure (adjusted for water vapor).
8. A patient with pernicious anemia lacks intrinsic factor. This
leads to decreased absorption of which vitamin?
A. Vitamin C
B. Vitamin B12 (cobalamin)
C. Folate
D. Vitamin D
Rationale: Intrinsic factor produced by gastric parietal cells is
required for vitamin B12 absorption in the ileum.
9. Which nerve provides sensory innervation to the anterior two-
thirds of the tongue?
A. Glossopharyngeal (CN IX)
B. Hypoglossal (CN XII)
C. Lingual branch of mandibular division of CN V (V3)
D. Facial nerve (chorda tympani)
Rationale: General somatic sensation (touch, pain) for the
anterior two-thirds is via the lingual nerve (V3); taste is via
chorda tympani (VII).
Exam Questions And Correct Answers
(Verified Answers) Plus Rationales
2026|2027 Q&A | Instant Download
1. The motor cortex responsible for voluntary movement is
located in which gyrus?
A. Superior temporal gyrus
B. Precentral gyrus
C. Postcentral gyrus
D. Precentral gyrus
Rationale: The primary motor cortex is located in the precentral
gyrus of the frontal lobe and controls voluntary movement.
2. Which amino acid is essential and a precursor for nitric oxide
synthesis?
A. Lysine
B. Arginine
,C. Glycine
D. Glutamine
Rationale: Arginine is the substrate for nitric oxide synthase,
producing nitric oxide.
3. Which heart valve prevents backflow from the left ventricle
into the left atrium?
A. Pulmonary valve
B. Tricuspid valve
C. Mitral (bicuspid) valve
D. Aortic valve
Rationale: The mitral valve (bicuspid) is between the left
atrium and left ventricle and prevents regurgitation during
systole.
4. A Gram-positive, catalase-positive cocci in clusters is most
likely:
A. Streptococcus pyogenes
B. Staphylococcus aureus
C. Enterococcus faecalis
D. Neisseria gonorrhoeae
Rationale: Staphylococci are Gram-positive cocci in clusters
and are catalase-positive; S. aureus is a common example.
,5. Which structure of the nephron is primarily responsible for
filtration?
A. Proximal tubule
B. Loop of Henle
C. Distal tubule
D. Glomerulus (Bowman capsule)
Rationale: Filtration of plasma into Bowman’s space occurs at
the glomerulus within Bowman capsule.
6. In glycolysis, the rate-limiting enzyme that converts fructose-
6-phosphate to fructose-1,6-bisphosphate is:
A. Hexokinase
B. Pyruvate kinase
C. Phosphofructokinase-1 (PFK-1)
D. Aldolase
Rationale: PFK-1 is the major regulatory, rate-limiting enzyme
of glycolysis.
7. The alveolar gas equation estimates alveolar O₂ tension.
Which variable is directly subtracted from inspired O₂ partial
pressure in the simplified alveolar gas equation?
A. PaCO₂/R (where R is respiratory quotient)
B. PaCO₂/R
, C. Water vapor pressure
D. Hemoglobin concentration
Rationale: The simplified alveolar gas equation subtracts
PaCO₂ divided by the respiratory quotient from inspired O₂
partial pressure (adjusted for water vapor).
8. A patient with pernicious anemia lacks intrinsic factor. This
leads to decreased absorption of which vitamin?
A. Vitamin C
B. Vitamin B12 (cobalamin)
C. Folate
D. Vitamin D
Rationale: Intrinsic factor produced by gastric parietal cells is
required for vitamin B12 absorption in the ileum.
9. Which nerve provides sensory innervation to the anterior two-
thirds of the tongue?
A. Glossopharyngeal (CN IX)
B. Hypoglossal (CN XII)
C. Lingual branch of mandibular division of CN V (V3)
D. Facial nerve (chorda tympani)
Rationale: General somatic sensation (touch, pain) for the
anterior two-thirds is via the lingual nerve (V3); taste is via
chorda tympani (VII).
