COMSAE Phase 1 Form 116 Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. A 24-year-old man presents with fever, sore throat, and posterior
cervical lymphadenopathy. A blood smear shows atypical
lymphocytes. Which virus is most likely responsible?
A. Cytomegalovirus
B. Epstein-Barr virus
C. Influenza A virus
D. Adenovirus
Correct answer: B. Epstein-Barr virus
Rationale: Epstein-Barr virus causes infectious mononucleosis
characterized by fever, pharyngitis, posterior cervical
lymphadenopathy, and atypical lymphocytes (Downey cells).
CMV can cause a mono-like illness but typically lacks prominent
pharyngitis.
2. Which structure is primarily responsible for producing
cerebrospinal fluid?
A. Arachnoid granulations
, B. Choroid plexus
C. Dura mater
D. Pia mater
Correct answer: B. Choroid plexus
Rationale: The choroid plexus in the ventricles produces
cerebrospinal fluid. Arachnoid granulations reabsorb CSF into
venous circulation.
3. A patient has weakness in wrist extension after a midshaft
humeral fracture. Which nerve is most likely injured?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Axillary nerve
Correct answer: C. Radial nerve
Rationale: The radial nerve runs in the radial groove of the
humerus and controls wrist and finger extension. Injury leads to
wrist drop.
4. Which enzyme is deficient in phenylketonuria (PKU)?
A. Tyrosinase
B. Phenylalanine hydroxylase
C. Homogentisate oxidase
, D. DOPA decarboxylase
Correct answer: B. Phenylalanine hydroxylase
Rationale: PKU is caused by deficiency of phenylalanine
hydroxylase, leading to accumulation of phenylalanine and
intellectual disability if untreated.
5. Which heart sound is associated with closure of the semilunar
valves?
A. S1
B. S2
C. S3
D. S4
Correct answer: B. S2
Rationale: S2 is produced by closure of the aortic and pulmonic
valves at the end of systole.
6. A patient presents with COPD and elevated PaCO₂. What is the
primary renal compensation?
A. Decreased bicarbonate reabsorption
B. Increased bicarbonate retention
C. Decreased hydrogen secretion
D. Increased ammonia excretion
Correct answer: B. Increased bicarbonate retention
, Rationale: In chronic respiratory acidosis, the kidneys
compensate by increasing bicarbonate reabsorption and
hydrogen ion excretion.
7. Which type of hypersensitivity reaction is involved in rheumatoid
arthritis?
A. Type I
B. Type II
C. Type III
D. Type IV
Correct answer: C. Type III
Rationale: Rheumatoid arthritis involves immune complex
deposition (type III hypersensitivity) leading to synovial
inflammation.
8. Which vitamin deficiency causes night blindness?
A. Vitamin A
B. Vitamin D
C. Vitamin K
D. Vitamin E
Correct answer: A. Vitamin A
Rationale: Vitamin A is required for rhodopsin formation in
retinal rods; deficiency leads to night blindness.
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. A 24-year-old man presents with fever, sore throat, and posterior
cervical lymphadenopathy. A blood smear shows atypical
lymphocytes. Which virus is most likely responsible?
A. Cytomegalovirus
B. Epstein-Barr virus
C. Influenza A virus
D. Adenovirus
Correct answer: B. Epstein-Barr virus
Rationale: Epstein-Barr virus causes infectious mononucleosis
characterized by fever, pharyngitis, posterior cervical
lymphadenopathy, and atypical lymphocytes (Downey cells).
CMV can cause a mono-like illness but typically lacks prominent
pharyngitis.
2. Which structure is primarily responsible for producing
cerebrospinal fluid?
A. Arachnoid granulations
, B. Choroid plexus
C. Dura mater
D. Pia mater
Correct answer: B. Choroid plexus
Rationale: The choroid plexus in the ventricles produces
cerebrospinal fluid. Arachnoid granulations reabsorb CSF into
venous circulation.
3. A patient has weakness in wrist extension after a midshaft
humeral fracture. Which nerve is most likely injured?
A. Median nerve
B. Ulnar nerve
C. Radial nerve
D. Axillary nerve
Correct answer: C. Radial nerve
Rationale: The radial nerve runs in the radial groove of the
humerus and controls wrist and finger extension. Injury leads to
wrist drop.
4. Which enzyme is deficient in phenylketonuria (PKU)?
A. Tyrosinase
B. Phenylalanine hydroxylase
C. Homogentisate oxidase
, D. DOPA decarboxylase
Correct answer: B. Phenylalanine hydroxylase
Rationale: PKU is caused by deficiency of phenylalanine
hydroxylase, leading to accumulation of phenylalanine and
intellectual disability if untreated.
5. Which heart sound is associated with closure of the semilunar
valves?
A. S1
B. S2
C. S3
D. S4
Correct answer: B. S2
Rationale: S2 is produced by closure of the aortic and pulmonic
valves at the end of systole.
6. A patient presents with COPD and elevated PaCO₂. What is the
primary renal compensation?
A. Decreased bicarbonate reabsorption
B. Increased bicarbonate retention
C. Decreased hydrogen secretion
D. Increased ammonia excretion
Correct answer: B. Increased bicarbonate retention
, Rationale: In chronic respiratory acidosis, the kidneys
compensate by increasing bicarbonate reabsorption and
hydrogen ion excretion.
7. Which type of hypersensitivity reaction is involved in rheumatoid
arthritis?
A. Type I
B. Type II
C. Type III
D. Type IV
Correct answer: C. Type III
Rationale: Rheumatoid arthritis involves immune complex
deposition (type III hypersensitivity) leading to synovial
inflammation.
8. Which vitamin deficiency causes night blindness?
A. Vitamin A
B. Vitamin D
C. Vitamin K
D. Vitamin E
Correct answer: A. Vitamin A
Rationale: Vitamin A is required for rhodopsin formation in
retinal rods; deficiency leads to night blindness.
