COMSAE Phase 1 Form ASA 125
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 24-year-old woman has fatigue, pallor, and a low hemoglobin
level. Laboratory studies show decreased mean corpuscular volume
and increased total iron-binding capacity. Which finding is most
consistent with her condition?
A. Increased ferritin
B. Decreased transferrin
C. Decreased serum iron
D. Increased vitamin B12
Answer: C. Decreased serum iron
Rationale: Iron deficiency anemia is characterized by decreased serum
iron, increased total iron-binding capacity, and decreased ferritin due
to depleted iron stores.
2. A mutation causes replacement of a glutamic acid residue with
valine in the beta-globin chain of hemoglobin. Which disease results?
A. Thalassemia
B. Sickle cell disease
,C. Hereditary spherocytosis
D. G6PD deficiency
Answer: B. Sickle cell disease
Rationale: Sickle cell disease results from a point mutation in beta-
globin causing substitution of valine for glutamic acid, producing HbS.
3. A patient develops muscle weakness after administration of a
medication that blocks acetylcholine receptors at the neuromuscular
junction. Which receptor is affected?
A. Muscarinic receptor
B. Nicotinic receptor
C. Adrenergic receptor
D. Dopamine receptor
Answer: B. Nicotinic receptor
Rationale: Skeletal muscle contraction depends on nicotinic
acetylcholine receptors located at the neuromuscular junction.
4. A Gram-positive organism forms clusters and is catalase positive.
Which organism is most likely?
A. Streptococcus pyogenes
B. Staphylococcus aureus
C. Enterococcus faecalis
D. Streptococcus pneumoniae
Answer: B. Staphylococcus aureus
Rationale: Staphylococcus species are gram-positive cocci arranged in
clusters and are catalase positive.
,5. A patient has damage to the dorsal columns of the spinal cord.
Which sensory deficit occurs?
A. Pain loss
B. Temperature loss
C. Loss of vibration and proprioception
D. Loss of motor function only
Answer: C. Loss of vibration and proprioception
Rationale: The dorsal column-medial lemniscus pathway carries
vibration, fine touch, and proprioception.
6. Which enzyme converts angiotensin I into angiotensin II?
A. Renin
B. ACE
C. Aldosterone synthase
D. Renal dehydrogenase
Answer: B. ACE
Rationale: Angiotensin-converting enzyme converts angiotensin I into
angiotensin II, which increases vasoconstriction and aldosterone
secretion.
7. A child has recurrent infections with catalase-positive bacteria due
to defective oxidative burst. Which condition is present?
A. Bruton's agammaglobulinemia
B. Chronic granulomatous disease
, C. DiGeorge syndrome
D. SCID
Answer: B. Chronic granulomatous disease
Rationale: Chronic granulomatous disease results from NADPH
oxidase deficiency causing impaired killing of catalase-positive
organisms.
8. Which immunoglobulin crosses the placenta?
A. IgA
B. IgM
C. IgG
D. IgE
Answer: C. IgG
Rationale: IgG is the only immunoglobulin that crosses the placenta
and provides passive fetal immunity.
9. A drug competitively inhibits an enzyme by binding the active site.
What happens to Km?
A. Decreases
B. Increases
C. No change
D. Enzyme destroyed
Answer: B. Increases
Rationale: Competitive inhibition increases Km because more
substrate is needed to reach half-maximal velocity.
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 24-year-old woman has fatigue, pallor, and a low hemoglobin
level. Laboratory studies show decreased mean corpuscular volume
and increased total iron-binding capacity. Which finding is most
consistent with her condition?
A. Increased ferritin
B. Decreased transferrin
C. Decreased serum iron
D. Increased vitamin B12
Answer: C. Decreased serum iron
Rationale: Iron deficiency anemia is characterized by decreased serum
iron, increased total iron-binding capacity, and decreased ferritin due
to depleted iron stores.
2. A mutation causes replacement of a glutamic acid residue with
valine in the beta-globin chain of hemoglobin. Which disease results?
A. Thalassemia
B. Sickle cell disease
,C. Hereditary spherocytosis
D. G6PD deficiency
Answer: B. Sickle cell disease
Rationale: Sickle cell disease results from a point mutation in beta-
globin causing substitution of valine for glutamic acid, producing HbS.
3. A patient develops muscle weakness after administration of a
medication that blocks acetylcholine receptors at the neuromuscular
junction. Which receptor is affected?
A. Muscarinic receptor
B. Nicotinic receptor
C. Adrenergic receptor
D. Dopamine receptor
Answer: B. Nicotinic receptor
Rationale: Skeletal muscle contraction depends on nicotinic
acetylcholine receptors located at the neuromuscular junction.
4. A Gram-positive organism forms clusters and is catalase positive.
Which organism is most likely?
A. Streptococcus pyogenes
B. Staphylococcus aureus
C. Enterococcus faecalis
D. Streptococcus pneumoniae
Answer: B. Staphylococcus aureus
Rationale: Staphylococcus species are gram-positive cocci arranged in
clusters and are catalase positive.
,5. A patient has damage to the dorsal columns of the spinal cord.
Which sensory deficit occurs?
A. Pain loss
B. Temperature loss
C. Loss of vibration and proprioception
D. Loss of motor function only
Answer: C. Loss of vibration and proprioception
Rationale: The dorsal column-medial lemniscus pathway carries
vibration, fine touch, and proprioception.
6. Which enzyme converts angiotensin I into angiotensin II?
A. Renin
B. ACE
C. Aldosterone synthase
D. Renal dehydrogenase
Answer: B. ACE
Rationale: Angiotensin-converting enzyme converts angiotensin I into
angiotensin II, which increases vasoconstriction and aldosterone
secretion.
7. A child has recurrent infections with catalase-positive bacteria due
to defective oxidative burst. Which condition is present?
A. Bruton's agammaglobulinemia
B. Chronic granulomatous disease
, C. DiGeorge syndrome
D. SCID
Answer: B. Chronic granulomatous disease
Rationale: Chronic granulomatous disease results from NADPH
oxidase deficiency causing impaired killing of catalase-positive
organisms.
8. Which immunoglobulin crosses the placenta?
A. IgA
B. IgM
C. IgG
D. IgE
Answer: C. IgG
Rationale: IgG is the only immunoglobulin that crosses the placenta
and provides passive fetal immunity.
9. A drug competitively inhibits an enzyme by binding the active site.
What happens to Km?
A. Decreases
B. Increases
C. No change
D. Enzyme destroyed
Answer: B. Increases
Rationale: Competitive inhibition increases Km because more
substrate is needed to reach half-maximal velocity.
