COMSAE Phase 1 Form ASA 116
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 7-month-old infant presents with developmental delay,
hypotonia, hepatomegaly, and fasting hypoglycemia. Laboratory
studies show elevated glycogen storage with increased glycogen
branching abnormalities. Which enzyme deficiency is most likely
responsible?
A. Glucose-6-phosphatase
B. Lysosomal acid maltase
C. Glycogen branching enzyme
D. Glycogen phosphorylase
Answer: C. Glycogen branching enzyme
Rationale: Deficiency of glycogen branching enzyme causes Andersen
disease (glycogen storage disease type IV), producing abnormal
glycogen accumulation, hepatosplenomegaly, progressive liver
dysfunction, and hypoglycemia. Glucose-6-phosphatase deficiency
causes von Gierke disease, while lysosomal acid maltase deficiency
causes Pompe disease.
2. A researcher blocks RNA polymerase II activity in a human cell
culture. Which process is directly impaired?
,A. Ribosomal RNA synthesis
B. Transfer RNA synthesis
C. Messenger RNA synthesis
D. DNA replication
Answer: C. Messenger RNA synthesis
Rationale: RNA polymerase II synthesizes mRNA from DNA templates.
RNA polymerase I produces rRNA, and RNA polymerase III produces
tRNA and small RNAs.
3. A patient with a mutation affecting mitochondrial DNA develops a
multisystem disorder. Which inheritance pattern is most likely?
A. Autosomal dominant
B. Autosomal recessive
C. X-linked recessive
D. Maternal inheritance
Answer: D. Maternal inheritance
Rationale: Mitochondria are inherited from the mother because the
ovum contributes the majority of cytoplasmic organelles to the
embryo. Mitochondrial diseases often affect tissues with high energy
requirements such as muscle and nervous tissue.
4. A patient with chronic hypertension develops increased cardiac
wall thickness. Which cellular adaptation explains this finding?
A. Hyperplasia
B. Hypertrophy
C. Metaplasia
D. Dysplasia
,Answer: B. Hypertrophy
Rationale: Cardiac myocytes cannot efficiently divide, so chronic
pressure overload causes increased cell size through addition of
sarcomeres, resulting in hypertrophy.
5. A patient has difficulty converting phenylalanine into tyrosine.
Which enzyme deficiency causes this condition?
A. Homogentisate oxidase
B. Phenylalanine hydroxylase
C. Tyrosinase
D. Dihydrofolate reductase
Answer: B. Phenylalanine hydroxylase
Rationale: Phenylalanine hydroxylase converts phenylalanine into
tyrosine. Deficiency causes phenylketonuria, characterized by
intellectual disability, seizures, and musty odor if untreated.
6. A patient taking a medication develops prolonged QT interval due
to delayed ventricular repolarization. Which ion channel is most
likely affected?
A. Sodium channel
B. Calcium channel
C. Potassium channel
D. Chloride channel
Answer: C. Potassium channel
Rationale: Repolarization of cardiac myocytes depends primarily on
potassium efflux through delayed rectifier potassium channels.
, Blockade can prolong the QT interval and predispose to torsades de
pointes.
7. A patient with severe bacterial infection develops septic shock.
Which inflammatory mediator contributes most directly to
systemic vasodilation?
A. IL-1
B. TNF-alpha
C. Nitric oxide
D. Histamine
Answer: C. Nitric oxide
Rationale: Nitric oxide released from endothelial cells causes smooth
muscle relaxation and widespread vasodilation. TNF-alpha and IL-1
contribute to inflammation but are not the direct vasodilatory
mediator.
8. A child has recurrent infections with catalase-positive organisms
and impaired neutrophil oxidative burst. Which enzyme is
defective?
A. Myeloperoxidase
B. NADPH oxidase
C. Superoxide dismutase
D. Glutathione peroxidase
Answer: B. NADPH oxidase
Rationale: Chronic granulomatous disease results from NADPH
oxidase deficiency, preventing production of reactive oxygen species
needed for intracellular killing of catalase-positive bacteria and fungi.
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 7-month-old infant presents with developmental delay,
hypotonia, hepatomegaly, and fasting hypoglycemia. Laboratory
studies show elevated glycogen storage with increased glycogen
branching abnormalities. Which enzyme deficiency is most likely
responsible?
A. Glucose-6-phosphatase
B. Lysosomal acid maltase
C. Glycogen branching enzyme
D. Glycogen phosphorylase
Answer: C. Glycogen branching enzyme
Rationale: Deficiency of glycogen branching enzyme causes Andersen
disease (glycogen storage disease type IV), producing abnormal
glycogen accumulation, hepatosplenomegaly, progressive liver
dysfunction, and hypoglycemia. Glucose-6-phosphatase deficiency
causes von Gierke disease, while lysosomal acid maltase deficiency
causes Pompe disease.
2. A researcher blocks RNA polymerase II activity in a human cell
culture. Which process is directly impaired?
,A. Ribosomal RNA synthesis
B. Transfer RNA synthesis
C. Messenger RNA synthesis
D. DNA replication
Answer: C. Messenger RNA synthesis
Rationale: RNA polymerase II synthesizes mRNA from DNA templates.
RNA polymerase I produces rRNA, and RNA polymerase III produces
tRNA and small RNAs.
3. A patient with a mutation affecting mitochondrial DNA develops a
multisystem disorder. Which inheritance pattern is most likely?
A. Autosomal dominant
B. Autosomal recessive
C. X-linked recessive
D. Maternal inheritance
Answer: D. Maternal inheritance
Rationale: Mitochondria are inherited from the mother because the
ovum contributes the majority of cytoplasmic organelles to the
embryo. Mitochondrial diseases often affect tissues with high energy
requirements such as muscle and nervous tissue.
4. A patient with chronic hypertension develops increased cardiac
wall thickness. Which cellular adaptation explains this finding?
A. Hyperplasia
B. Hypertrophy
C. Metaplasia
D. Dysplasia
,Answer: B. Hypertrophy
Rationale: Cardiac myocytes cannot efficiently divide, so chronic
pressure overload causes increased cell size through addition of
sarcomeres, resulting in hypertrophy.
5. A patient has difficulty converting phenylalanine into tyrosine.
Which enzyme deficiency causes this condition?
A. Homogentisate oxidase
B. Phenylalanine hydroxylase
C. Tyrosinase
D. Dihydrofolate reductase
Answer: B. Phenylalanine hydroxylase
Rationale: Phenylalanine hydroxylase converts phenylalanine into
tyrosine. Deficiency causes phenylketonuria, characterized by
intellectual disability, seizures, and musty odor if untreated.
6. A patient taking a medication develops prolonged QT interval due
to delayed ventricular repolarization. Which ion channel is most
likely affected?
A. Sodium channel
B. Calcium channel
C. Potassium channel
D. Chloride channel
Answer: C. Potassium channel
Rationale: Repolarization of cardiac myocytes depends primarily on
potassium efflux through delayed rectifier potassium channels.
, Blockade can prolong the QT interval and predispose to torsades de
pointes.
7. A patient with severe bacterial infection develops septic shock.
Which inflammatory mediator contributes most directly to
systemic vasodilation?
A. IL-1
B. TNF-alpha
C. Nitric oxide
D. Histamine
Answer: C. Nitric oxide
Rationale: Nitric oxide released from endothelial cells causes smooth
muscle relaxation and widespread vasodilation. TNF-alpha and IL-1
contribute to inflammation but are not the direct vasodilatory
mediator.
8. A child has recurrent infections with catalase-positive organisms
and impaired neutrophil oxidative burst. Which enzyme is
defective?
A. Myeloperoxidase
B. NADPH oxidase
C. Superoxide dismutase
D. Glutathione peroxidase
Answer: B. NADPH oxidase
Rationale: Chronic granulomatous disease results from NADPH
oxidase deficiency, preventing production of reactive oxygen species
needed for intracellular killing of catalase-positive bacteria and fungi.
