COMSAE Phase 1 Form 113 Questions With
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. A 24-year-old woman presents with fatigue and pallor. Lab results
show microcytic hypochromic anemia and low ferritin. Which of
the following is the most likely diagnosis?
A. Iron deficiency anemia
B. Anemia of chronic disease
C. Thalassemia major
D. Sideroblastic anemia
Answer: A
Iron deficiency anemia is the most common cause of microcytic
anemia and is characterized by low ferritin, low serum iron, and
elevated total iron-binding capacity (TIBC).
2. A patient has a mutation affecting the beta chain of hemoglobin
leading to substitution of valine for glutamic acid. What is the
diagnosis?
A. HbC disease
B. Sickle cell disease
, C. Beta-thalassemia
D. Iron deficiency anemia
Answer: B
The Glu→Val substitution in the beta-globin chain causes
hemoglobin S formation, leading to sickling under low oxygen
conditions.
3. Which vitamin deficiency is associated with increased
methylmalonic acid levels?
A. Vitamin B1
B. Vitamin B6
C. Vitamin B12
D. Folate
Answer: C
Vitamin B12 deficiency leads to elevated methylmalonic acid and
homocysteine, whereas folate deficiency increases only
homocysteine.
4. A patient with COPD is most likely to have which acid-base
disorder?
A. Metabolic alkalosis
B. Respiratory alkalosis
C. Respiratory acidosis
, D. Metabolic acidosis
Answer: C
COPD causes hypoventilation and CO₂ retention, leading to
respiratory acidosis.
5. Which structure is derived from the endoderm?
A. Skin epidermis
B. CNS
C. GI tract epithelium
D. Muscle
Answer: C
Endoderm forms epithelial lining of the gastrointestinal and
respiratory tracts.
6. Which enzyme is deficient in phenylketonuria (PKU)?
A. Homogentisate oxidase
B. Phenylalanine hydroxylase
C. Tyrosinase
D. Dopamine beta-hydroxylase
Answer: B
PKU results from deficiency of phenylalanine hydroxylase,
leading to accumulation of phenylalanine.
, 7. A drug that competitively inhibits an enzyme will:
A. Decrease Vmax
B. Increase Km
C. Decrease Km
D. Eliminate enzyme activity
Answer: B
Competitive inhibition increases Km (decreased affinity) but does
not change Vmax.
8. Which type of hypersensitivity reaction is IgE mediated?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: A
Type I hypersensitivity involves IgE binding to mast cells causing
immediate allergic reactions.
9. Which organism is most associated with peptic ulcers?
A. Staphylococcus aureus
B. Helicobacter pylori
C. Streptococcus pyogenes
D. Escherichia coli
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant Download Pdf
1. A 24-year-old woman presents with fatigue and pallor. Lab results
show microcytic hypochromic anemia and low ferritin. Which of
the following is the most likely diagnosis?
A. Iron deficiency anemia
B. Anemia of chronic disease
C. Thalassemia major
D. Sideroblastic anemia
Answer: A
Iron deficiency anemia is the most common cause of microcytic
anemia and is characterized by low ferritin, low serum iron, and
elevated total iron-binding capacity (TIBC).
2. A patient has a mutation affecting the beta chain of hemoglobin
leading to substitution of valine for glutamic acid. What is the
diagnosis?
A. HbC disease
B. Sickle cell disease
, C. Beta-thalassemia
D. Iron deficiency anemia
Answer: B
The Glu→Val substitution in the beta-globin chain causes
hemoglobin S formation, leading to sickling under low oxygen
conditions.
3. Which vitamin deficiency is associated with increased
methylmalonic acid levels?
A. Vitamin B1
B. Vitamin B6
C. Vitamin B12
D. Folate
Answer: C
Vitamin B12 deficiency leads to elevated methylmalonic acid and
homocysteine, whereas folate deficiency increases only
homocysteine.
4. A patient with COPD is most likely to have which acid-base
disorder?
A. Metabolic alkalosis
B. Respiratory alkalosis
C. Respiratory acidosis
, D. Metabolic acidosis
Answer: C
COPD causes hypoventilation and CO₂ retention, leading to
respiratory acidosis.
5. Which structure is derived from the endoderm?
A. Skin epidermis
B. CNS
C. GI tract epithelium
D. Muscle
Answer: C
Endoderm forms epithelial lining of the gastrointestinal and
respiratory tracts.
6. Which enzyme is deficient in phenylketonuria (PKU)?
A. Homogentisate oxidase
B. Phenylalanine hydroxylase
C. Tyrosinase
D. Dopamine beta-hydroxylase
Answer: B
PKU results from deficiency of phenylalanine hydroxylase,
leading to accumulation of phenylalanine.
, 7. A drug that competitively inhibits an enzyme will:
A. Decrease Vmax
B. Increase Km
C. Decrease Km
D. Eliminate enzyme activity
Answer: B
Competitive inhibition increases Km (decreased affinity) but does
not change Vmax.
8. Which type of hypersensitivity reaction is IgE mediated?
A. Type I
B. Type II
C. Type III
D. Type IV
Answer: A
Type I hypersensitivity involves IgE binding to mast cells causing
immediate allergic reactions.
9. Which organism is most associated with peptic ulcers?
A. Staphylococcus aureus
B. Helicobacter pylori
C. Streptococcus pyogenes
D. Escherichia coli
