COMSAE PHASE 1-STYLE EXAM QUESTIONS AND
CORRECT ANSWERS (VERIFED ANSWERS) Q&A
2026|INSTANT DOWNLOAD PDF
1. Which organ is primarily responsible for detoxification of
ammonia into urea?
A. Kidney
B. Liver
C. Pancreas
D. Spleen
Rationale: The urea cycle occurs mainly in hepatocytes,
converting toxic ammonia into urea for excretion.
Correct answer: B. Liver
2. Which phase of the cell cycle is characterized by DNA
replication?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
Rationale: DNA synthesis occurs specifically during the S
(synthesis) phase.
Correct answer: B. S phase
,3. The primary site of iron absorption in the gastrointestinal
tract is the:
A. Stomach
B. Duodenum
C. Ileum
D. Colon
Rationale: Iron is mainly absorbed in the duodenum via
enterocytes.
Correct answer: B. Duodenum
4. Which vitamin is required for synthesis of clotting factors II,
VII, IX, and X?
A. Vitamin A
B. Vitamin C
C. Vitamin K
D. Vitamin D
Rationale: Vitamin K is essential for γ-carboxylation of clotting
factors.
Correct answer: C. Vitamin K
5. Which neurotransmitter is primarily involved in the
parasympathetic nervous system?
,A. Dopamine
B. Norepinephrine
C. Acetylcholine
D. Serotonin
Rationale: Acetylcholine is the main neurotransmitter of
parasympathetic postganglionic neurons.
Correct answer: C. Acetylcholine
6. Which part of the nephron is responsible for the majority of
sodium reabsorption?
A. Collecting duct
B. Distal convoluted tubule
C. Proximal convoluted tubule
D. Loop of Henle (ascending limb)
Rationale: The proximal tubule reabsorbs about 65–70% of
filtered sodium.
Correct answer: C. Proximal convoluted tubule
7. The enzyme responsible for DNA replication is:
A. RNA polymerase
B. DNA ligase
C. DNA polymerase
D. Helicase
, Rationale: DNA polymerase synthesizes new DNA strands
during replication.
Correct answer: C. DNA polymerase
8. Which structure prevents backflow of blood from the left
ventricle to the left atrium?
A. Tricuspid valve
B. Mitral valve
C. Aortic valve
D. Pulmonary valve
Rationale: The mitral valve separates left atrium and left
ventricle.
Correct answer: B. Mitral valve
9. The primary buffer system in blood is:
A. Protein buffer system
B. Phosphate buffer system
C. Bicarbonate buffer system
D. Hemoglobin buffer system only
Rationale: The bicarbonate system regulates blood pH most
effectively.
Correct answer: C. Bicarbonate buffer system
CORRECT ANSWERS (VERIFED ANSWERS) Q&A
2026|INSTANT DOWNLOAD PDF
1. Which organ is primarily responsible for detoxification of
ammonia into urea?
A. Kidney
B. Liver
C. Pancreas
D. Spleen
Rationale: The urea cycle occurs mainly in hepatocytes,
converting toxic ammonia into urea for excretion.
Correct answer: B. Liver
2. Which phase of the cell cycle is characterized by DNA
replication?
A. G1 phase
B. S phase
C. G2 phase
D. M phase
Rationale: DNA synthesis occurs specifically during the S
(synthesis) phase.
Correct answer: B. S phase
,3. The primary site of iron absorption in the gastrointestinal
tract is the:
A. Stomach
B. Duodenum
C. Ileum
D. Colon
Rationale: Iron is mainly absorbed in the duodenum via
enterocytes.
Correct answer: B. Duodenum
4. Which vitamin is required for synthesis of clotting factors II,
VII, IX, and X?
A. Vitamin A
B. Vitamin C
C. Vitamin K
D. Vitamin D
Rationale: Vitamin K is essential for γ-carboxylation of clotting
factors.
Correct answer: C. Vitamin K
5. Which neurotransmitter is primarily involved in the
parasympathetic nervous system?
,A. Dopamine
B. Norepinephrine
C. Acetylcholine
D. Serotonin
Rationale: Acetylcholine is the main neurotransmitter of
parasympathetic postganglionic neurons.
Correct answer: C. Acetylcholine
6. Which part of the nephron is responsible for the majority of
sodium reabsorption?
A. Collecting duct
B. Distal convoluted tubule
C. Proximal convoluted tubule
D. Loop of Henle (ascending limb)
Rationale: The proximal tubule reabsorbs about 65–70% of
filtered sodium.
Correct answer: C. Proximal convoluted tubule
7. The enzyme responsible for DNA replication is:
A. RNA polymerase
B. DNA ligase
C. DNA polymerase
D. Helicase
, Rationale: DNA polymerase synthesizes new DNA strands
during replication.
Correct answer: C. DNA polymerase
8. Which structure prevents backflow of blood from the left
ventricle to the left atrium?
A. Tricuspid valve
B. Mitral valve
C. Aortic valve
D. Pulmonary valve
Rationale: The mitral valve separates left atrium and left
ventricle.
Correct answer: B. Mitral valve
9. The primary buffer system in blood is:
A. Protein buffer system
B. Phosphate buffer system
C. Bicarbonate buffer system
D. Hemoglobin buffer system only
Rationale: The bicarbonate system regulates blood pH most
effectively.
Correct answer: C. Bicarbonate buffer system
