COMSAE Phase 1-Form ASA 114
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 22-year-old patient has a mutation affecting the promoter
region of a gene. Which molecular process is most directly
impaired?
A. DNA replication
B. RNA transcription initiation
C. Protein folding
D. mRNA degradation
Answer: B. RNA transcription initiation
Rationale: The promoter region is the DNA sequence where
transcription factors and RNA polymerase bind to initiate
transcription. A promoter mutation decreases or prevents formation
of mRNA from the affected gene.
2. A patient with a mitochondrial disorder has impaired ATP
production. Which cellular structure is primarily responsible for
oxidative phosphorylation?
A. Golgi apparatus
B. Lysosome
,C. Mitochondrial inner membrane
D. Nuclear envelope
Answer: C. Mitochondrial inner membrane
Rationale: The electron transport chain and ATP synthase are located
in the inner mitochondrial membrane. Proton gradients generated
here drive ATP production through oxidative phosphorylation.
3. A newborn has recurrent infections caused by catalase-positive
organisms. Testing reveals defective neutrophil oxidative burst.
Which enzyme is most likely deficient?
A. Myeloperoxidase
B. NADPH oxidase
C. Superoxide dismutase
D. Catalase
Answer: B. NADPH oxidase
Rationale: Chronic granulomatous disease results from NADPH
oxidase deficiency, impairing production of reactive oxygen species
needed for killing catalase-positive bacteria and fungi.
4. A mutation causes substitution of one amino acid for another in a
hemoglobin protein. What type of mutation is this?
A. Frameshift mutation
B. Silent mutation
C. Missense mutation
D. Nonsense mutation
Answer: C. Missense mutation
,Rationale: A missense mutation changes one amino acid within a
protein sequence. Sickle cell disease results from a missense mutation
replacing glutamic acid with valine in β-globin.
5. A drug inhibits microtubule formation during cell division. Which
process is most affected?
A. DNA synthesis
B. Chromosome separation
C. Protein translation
D. RNA processing
Answer: B. Chromosome separation
Rationale: Microtubules form the mitotic spindle, which separates
chromosomes during mitosis. Disruption causes abnormal cell division.
6. A patient has decreased plasma oncotic pressure due to low
albumin levels. Which physiological change occurs?
A. Increased vascular reabsorption
B. Increased edema formation
C. Decreased capillary filtration
D. Increased blood viscosity
Answer: B. Increased edema formation
Rationale: Albumin maintains plasma oncotic pressure. Low albumin
decreases fluid retention in vessels, causing movement of fluid into
tissues and edema.
, 7. A patient with respiratory alkalosis develops decreased calcium
binding to albumin. What symptom may occur?
A. Muscle weakness from hypercalcemia
B. Tetany from decreased ionized calcium
C. Increased bone formation
D. Severe hypokalemia only
Answer: B. Tetany from decreased ionized calcium
Rationale: Alkalosis increases calcium binding to albumin, lowering
free ionized calcium and causing neuromuscular irritability and
tetany.
8. Which immunoglobulin is primarily responsible for mucosal
immunity?
A. IgG
B. IgM
C. IgA
D. IgE
Answer: C. IgA
Rationale: IgA is secreted in mucosal surfaces, saliva, tears, and breast
milk and provides protection against pathogens entering through
mucosal membranes.
9. A patient has absent thymic development. Which immune cell
population is most affected?
A. B lymphocytes
B. T lymphocytes
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 22-year-old patient has a mutation affecting the promoter
region of a gene. Which molecular process is most directly
impaired?
A. DNA replication
B. RNA transcription initiation
C. Protein folding
D. mRNA degradation
Answer: B. RNA transcription initiation
Rationale: The promoter region is the DNA sequence where
transcription factors and RNA polymerase bind to initiate
transcription. A promoter mutation decreases or prevents formation
of mRNA from the affected gene.
2. A patient with a mitochondrial disorder has impaired ATP
production. Which cellular structure is primarily responsible for
oxidative phosphorylation?
A. Golgi apparatus
B. Lysosome
,C. Mitochondrial inner membrane
D. Nuclear envelope
Answer: C. Mitochondrial inner membrane
Rationale: The electron transport chain and ATP synthase are located
in the inner mitochondrial membrane. Proton gradients generated
here drive ATP production through oxidative phosphorylation.
3. A newborn has recurrent infections caused by catalase-positive
organisms. Testing reveals defective neutrophil oxidative burst.
Which enzyme is most likely deficient?
A. Myeloperoxidase
B. NADPH oxidase
C. Superoxide dismutase
D. Catalase
Answer: B. NADPH oxidase
Rationale: Chronic granulomatous disease results from NADPH
oxidase deficiency, impairing production of reactive oxygen species
needed for killing catalase-positive bacteria and fungi.
4. A mutation causes substitution of one amino acid for another in a
hemoglobin protein. What type of mutation is this?
A. Frameshift mutation
B. Silent mutation
C. Missense mutation
D. Nonsense mutation
Answer: C. Missense mutation
,Rationale: A missense mutation changes one amino acid within a
protein sequence. Sickle cell disease results from a missense mutation
replacing glutamic acid with valine in β-globin.
5. A drug inhibits microtubule formation during cell division. Which
process is most affected?
A. DNA synthesis
B. Chromosome separation
C. Protein translation
D. RNA processing
Answer: B. Chromosome separation
Rationale: Microtubules form the mitotic spindle, which separates
chromosomes during mitosis. Disruption causes abnormal cell division.
6. A patient has decreased plasma oncotic pressure due to low
albumin levels. Which physiological change occurs?
A. Increased vascular reabsorption
B. Increased edema formation
C. Decreased capillary filtration
D. Increased blood viscosity
Answer: B. Increased edema formation
Rationale: Albumin maintains plasma oncotic pressure. Low albumin
decreases fluid retention in vessels, causing movement of fluid into
tissues and edema.
, 7. A patient with respiratory alkalosis develops decreased calcium
binding to albumin. What symptom may occur?
A. Muscle weakness from hypercalcemia
B. Tetany from decreased ionized calcium
C. Increased bone formation
D. Severe hypokalemia only
Answer: B. Tetany from decreased ionized calcium
Rationale: Alkalosis increases calcium binding to albumin, lowering
free ionized calcium and causing neuromuscular irritability and
tetany.
8. Which immunoglobulin is primarily responsible for mucosal
immunity?
A. IgG
B. IgM
C. IgA
D. IgE
Answer: C. IgA
Rationale: IgA is secreted in mucosal surfaces, saliva, tears, and breast
milk and provides protection against pathogens entering through
mucosal membranes.
9. A patient has absent thymic development. Which immune cell
population is most affected?
A. B lymphocytes
B. T lymphocytes
