COMSAE Phase 1 Form 113 Practice Exam
Questions And Correct ANSWERs (Verified
ANSWERs) Plus Rationales 2025/2026 Q&A
ACTUAL!!!!
1. The motor cortex responsible for voluntary movement is located in which gyrus?
A. Superior temporal gyrus
B. Precentral gyrus
C. Postcentral gyrus
D. Inferior frontal gyrus
Correct ANSWER: B. Precentral gyrus
Rationale: The primary motor cortex is located in the precentral gyrus of the frontal lobe and
controls voluntary movement. The superior temporal gyrus is involved in auditory processing,
the postcentral gyrus is the primary somatosensory cortex, and the inferior frontal gyrus
contains Broca's area for speech production.
2. Which amino acid is essential and a precursor for nitric oxide synthesis?
A. Lysine
,B. Arginine
C. Glycine
D. Glutamine
Correct ANSWER: B. Arginine
Rationale: Arginine is the substrate for nitric oxide synthase, producing nitric oxide and
citrulline. Lysine is an essential amino acid involved in protein synthesis, glycine is a non-
essential amino acid and neurotransmitter, and glutamine is involved in nitrogen transport and
ammonia detoxification.
3. Which heart valve prevents backflow from the left ventricle into the left atrium?
A. Pulmonary valve
B. Aortic valve
C. Mitral valve
D. Tricuspid valve
Correct ANSWER: C. Mitral valve
Rationale: The mitral valve (bicuspid valve) prevents backflow from the left ventricle into the
left atrium during ventricular systole. The pulmonary valve prevents backflow from the
pulmonary artery into the right ventricle, the aortic valve prevents backflow from the aorta into
the left ventricle, and the tricuspid valve prevents backflow from the right ventricle into the
right atrium.
4. Which cranial nerve is responsible for the sensation of smell?
A. Cranial nerve II
,B. Cranial nerve I
C. Cranial nerve VIII
D. Cranial nerve V
Correct ANSWER: B. Cranial nerve I
Rationale: The olfactory nerve (CN I) is responsible for the sense of smell. CN II is the optic
nerve for vision, CN VIII is the vestibulocochlear nerve for hearing and balance, and CN V is the
trigeminal nerve for facial sensation and mastication.
5. What is the primary function of the juxtaglomerular apparatus?
A. Filtration of blood
B. Regulation of blood pressure
C. Reabsorption of water
D. Secretion of hormones
Correct ANSWER: B. Regulation of blood pressure
Rationale: The juxtaglomerular apparatus regulates blood pressure through the renin-
angiotensin-aldosterone system by releasing renin in response to decreased renal blood
pressure or sodium concentration. Filtration occurs in the glomerulus, water reabsorption
occurs throughout the nephron, and hormone secretion is a function of endocrine glands.
6. Which enzyme is responsible for the conversion of angiotensin I to angiotensin II?
A. Renin
B. ACE
C. Aldosterone
, D. ADH
Correct ANSWER: B. ACE
Rationale: Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II,
primarily in the lungs. Renin converts angiotensinogen to angiotensin I, aldosterone promotes
sodium reabsorption, and ADH promotes water reabsorption.
7. The optic disc is characterized by which of the following?
A. Highest concentration of cones
B. Site of highest visual acuity
C. Blind spot lacking photoreceptors
D. Area of greatest light sensitivity
Correct ANSWER: C. Blind spot lacking photoreceptors
Rationale: The optic disc is the blind spot where the optic nerve exits the eye and lacks
photoreceptors. The fovea contains the highest concentration of cones and is the site of highest
visual acuity. The macula is the area of greatest light sensitivity.
8. Which neurotransmitter is primarily associated with the parasympathetic nervous system?
A. Norepinephrine
B. Dopamine
C. Acetylcholine
D. Serotonin
Questions And Correct ANSWERs (Verified
ANSWERs) Plus Rationales 2025/2026 Q&A
ACTUAL!!!!
1. The motor cortex responsible for voluntary movement is located in which gyrus?
A. Superior temporal gyrus
B. Precentral gyrus
C. Postcentral gyrus
D. Inferior frontal gyrus
Correct ANSWER: B. Precentral gyrus
Rationale: The primary motor cortex is located in the precentral gyrus of the frontal lobe and
controls voluntary movement. The superior temporal gyrus is involved in auditory processing,
the postcentral gyrus is the primary somatosensory cortex, and the inferior frontal gyrus
contains Broca's area for speech production.
2. Which amino acid is essential and a precursor for nitric oxide synthesis?
A. Lysine
,B. Arginine
C. Glycine
D. Glutamine
Correct ANSWER: B. Arginine
Rationale: Arginine is the substrate for nitric oxide synthase, producing nitric oxide and
citrulline. Lysine is an essential amino acid involved in protein synthesis, glycine is a non-
essential amino acid and neurotransmitter, and glutamine is involved in nitrogen transport and
ammonia detoxification.
3. Which heart valve prevents backflow from the left ventricle into the left atrium?
A. Pulmonary valve
B. Aortic valve
C. Mitral valve
D. Tricuspid valve
Correct ANSWER: C. Mitral valve
Rationale: The mitral valve (bicuspid valve) prevents backflow from the left ventricle into the
left atrium during ventricular systole. The pulmonary valve prevents backflow from the
pulmonary artery into the right ventricle, the aortic valve prevents backflow from the aorta into
the left ventricle, and the tricuspid valve prevents backflow from the right ventricle into the
right atrium.
4. Which cranial nerve is responsible for the sensation of smell?
A. Cranial nerve II
,B. Cranial nerve I
C. Cranial nerve VIII
D. Cranial nerve V
Correct ANSWER: B. Cranial nerve I
Rationale: The olfactory nerve (CN I) is responsible for the sense of smell. CN II is the optic
nerve for vision, CN VIII is the vestibulocochlear nerve for hearing and balance, and CN V is the
trigeminal nerve for facial sensation and mastication.
5. What is the primary function of the juxtaglomerular apparatus?
A. Filtration of blood
B. Regulation of blood pressure
C. Reabsorption of water
D. Secretion of hormones
Correct ANSWER: B. Regulation of blood pressure
Rationale: The juxtaglomerular apparatus regulates blood pressure through the renin-
angiotensin-aldosterone system by releasing renin in response to decreased renal blood
pressure or sodium concentration. Filtration occurs in the glomerulus, water reabsorption
occurs throughout the nephron, and hormone secretion is a function of endocrine glands.
6. Which enzyme is responsible for the conversion of angiotensin I to angiotensin II?
A. Renin
B. ACE
C. Aldosterone
, D. ADH
Correct ANSWER: B. ACE
Rationale: Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II,
primarily in the lungs. Renin converts angiotensinogen to angiotensin I, aldosterone promotes
sodium reabsorption, and ADH promotes water reabsorption.
7. The optic disc is characterized by which of the following?
A. Highest concentration of cones
B. Site of highest visual acuity
C. Blind spot lacking photoreceptors
D. Area of greatest light sensitivity
Correct ANSWER: C. Blind spot lacking photoreceptors
Rationale: The optic disc is the blind spot where the optic nerve exits the eye and lacks
photoreceptors. The fovea contains the highest concentration of cones and is the site of highest
visual acuity. The macula is the area of greatest light sensitivity.
8. Which neurotransmitter is primarily associated with the parasympathetic nervous system?
A. Norepinephrine
B. Dopamine
C. Acetylcholine
D. Serotonin
