COMSAE-113-Practice-Exam-
2026-100-QA-Rationales-NBOME-
COMLEX-Review.pdf
1.
The primary motor cortex responsible for voluntary movement is located in which of the
following gyri?
A. Superior temporal gyrus
B. Precentral gyrus
C. Postcentral gyrus
D. Inferior frontal gyrus
Answer: B. Precentral gyrus
The primary motor cortex is in the precentral gyrus of the frontal lobe.
2.
Which amino acid serves as the precursor for nitric oxide synthesis in endothelial cells?
A. Lysine
B. Arginine
C. Glycine
D. Glutamine
Answer: B. Arginine
Arginine is converted to nitric oxide by nitric oxide synthase
3.
A decrease in which electrolyte is most likely to cause muscle cramps, tetany, and positive
Chvostek sign?
,A. Potassium
B. Calcium
C. Sodium
D. Magnesium
Answer: B. Calcium
Hypocalcemia increases neuromuscular excitability.
4.
Which part of the nephron is primarily responsible for the reabsorption of glucose under
normal conditions?
A. Loop of Henle
B. Distal convoluted tubule
C. Proximal convoluted tubule
D. Collecting duct
Answer: C. Proximal convoluted tubule
Glucose is reabsorbed via SGLT transporters in the PCT.
5.
Which organism is most commonly associated with lobar pneumonia in otherwise healthy
adults?
A. Staphylococcus aureus
B. Streptococcus pneumoniae
C. Klebsiella pneumoniae
D. Mycoplasma pneumoniae
Answer: B. Streptococcus pneumoniae
Most common cause of community-acquired pneumonia.
6.
Which hormone is responsible for increasing water reabsorption in the collecting ducts of
the kidney?
A. Aldosterone
B. ADH
,C. Renin
D. ANP
Answer: B. ADH
ADH increases water permeability via aquaporins.
7.
Which type of hypersensitivity reaction is mediated by immune complex deposition?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: C. Type III
Immune complexes deposit in tissues causing inflammation.
8.
A deficiency of which enzyme leads to accumulation of phenylalanine in phenylketonuria?
A. Tyrosinase
B. Phenylalanine hydroxylase
C. Dopa decarboxylase
D. Tyrosine kinase
Answer: B. Phenylalanine hydroxylase
PKU results from inability to convert phenylalanine to tyrosine.
9.
Which cranial nerve is responsible for lateral movement of the eye?
A. CN III
B. CN IV
C. CN VI
D. CN II
Answer: C. CN VI
Abducens nerve innervates lateral rectus muscle.
, 10.
Which condition is characterized by “blue bloater” appearance?
A. Emphysema
B. Chronic bronchitis
C. Asthma
D. Pulmonary fibrosis
Answer: B. Chronic bronchitis
Chronic bronchitis causes hypercapnia and cyanosis.
11.
Which structure carries oxygenated blood from the lungs to the heart?
A. Pulmonary artery
B. Pulmonary vein
C. Superior vena cava
D. Aorta
Answer: B. Pulmonary vein
Pulmonary veins carry oxygenated blood to the left atrium.
12.
Which vitamin deficiency leads to impaired collagen synthesis and bleeding gums?
A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin K
Answer: B. Vitamin C
Scurvy results from defective collagen formation.
13.
Which type of epithelium lines the alveoli of the lungs?
A. Stratified squamous
B. Simple cuboidal
2026-100-QA-Rationales-NBOME-
COMLEX-Review.pdf
1.
The primary motor cortex responsible for voluntary movement is located in which of the
following gyri?
A. Superior temporal gyrus
B. Precentral gyrus
C. Postcentral gyrus
D. Inferior frontal gyrus
Answer: B. Precentral gyrus
The primary motor cortex is in the precentral gyrus of the frontal lobe.
2.
Which amino acid serves as the precursor for nitric oxide synthesis in endothelial cells?
A. Lysine
B. Arginine
C. Glycine
D. Glutamine
Answer: B. Arginine
Arginine is converted to nitric oxide by nitric oxide synthase
3.
A decrease in which electrolyte is most likely to cause muscle cramps, tetany, and positive
Chvostek sign?
,A. Potassium
B. Calcium
C. Sodium
D. Magnesium
Answer: B. Calcium
Hypocalcemia increases neuromuscular excitability.
4.
Which part of the nephron is primarily responsible for the reabsorption of glucose under
normal conditions?
A. Loop of Henle
B. Distal convoluted tubule
C. Proximal convoluted tubule
D. Collecting duct
Answer: C. Proximal convoluted tubule
Glucose is reabsorbed via SGLT transporters in the PCT.
5.
Which organism is most commonly associated with lobar pneumonia in otherwise healthy
adults?
A. Staphylococcus aureus
B. Streptococcus pneumoniae
C. Klebsiella pneumoniae
D. Mycoplasma pneumoniae
Answer: B. Streptococcus pneumoniae
Most common cause of community-acquired pneumonia.
6.
Which hormone is responsible for increasing water reabsorption in the collecting ducts of
the kidney?
A. Aldosterone
B. ADH
,C. Renin
D. ANP
Answer: B. ADH
ADH increases water permeability via aquaporins.
7.
Which type of hypersensitivity reaction is mediated by immune complex deposition?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: C. Type III
Immune complexes deposit in tissues causing inflammation.
8.
A deficiency of which enzyme leads to accumulation of phenylalanine in phenylketonuria?
A. Tyrosinase
B. Phenylalanine hydroxylase
C. Dopa decarboxylase
D. Tyrosine kinase
Answer: B. Phenylalanine hydroxylase
PKU results from inability to convert phenylalanine to tyrosine.
9.
Which cranial nerve is responsible for lateral movement of the eye?
A. CN III
B. CN IV
C. CN VI
D. CN II
Answer: C. CN VI
Abducens nerve innervates lateral rectus muscle.
, 10.
Which condition is characterized by “blue bloater” appearance?
A. Emphysema
B. Chronic bronchitis
C. Asthma
D. Pulmonary fibrosis
Answer: B. Chronic bronchitis
Chronic bronchitis causes hypercapnia and cyanosis.
11.
Which structure carries oxygenated blood from the lungs to the heart?
A. Pulmonary artery
B. Pulmonary vein
C. Superior vena cava
D. Aorta
Answer: B. Pulmonary vein
Pulmonary veins carry oxygenated blood to the left atrium.
12.
Which vitamin deficiency leads to impaired collagen synthesis and bleeding gums?
A. Vitamin A
B. Vitamin C
C. Vitamin D
D. Vitamin K
Answer: B. Vitamin C
Scurvy results from defective collagen formation.
13.
Which type of epithelium lines the alveoli of the lungs?
A. Stratified squamous
B. Simple cuboidal
