COMSAE Phase 1 Form ASA 119
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 24-year-old man presents with recurrent infections involving
encapsulated bacteria. Laboratory testing reveals absence of
mature B cells due to a mutation affecting Bruton tyrosine kinase
(BTK). Which immune function is most directly impaired?
A. Activation of macrophages by interferon-gamma
B. Production of antibodies by plasma cells
C. Cytotoxic killing by CD8+ lymphocytes
D. Complement activation through the alternative pathway
Answer: B. Production of antibodies by plasma cells
Rationale: Bruton agammaglobulinemia results from defective B-cell
maturation due to BTK mutation. Without mature B cells, plasma cell
formation and immunoglobulin production are severely reduced,
leading to recurrent infections with encapsulated organisms.
2. A researcher studies a drug that blocks voltage-gated sodium
channels in neurons. Which phase of the action potential is
primarily affected?
,A. Resting membrane potential
B. Rapid depolarization phase
C. Repolarization phase
D. After-hyperpolarization phase
Answer: B. Rapid depolarization phase
Rationale: Voltage-gated sodium channels open during phase 0 of the
neuronal action potential, causing rapid sodium influx and
depolarization. Blocking these channels prevents initiation and
propagation of action potentials.
3. A patient with severe fasting hypoglycemia is found to have a
defect in glucose-6-phosphatase. Which metabolic process is
impaired?
A. Glycolysis
B. Glycogen synthesis
C. Release of glucose from the liver
D. Fatty acid oxidation
Answer: C. Release of glucose from the liver
Rationale: Glucose-6-phosphatase converts glucose-6-phosphate into
free glucose in hepatocytes. Deficiency causes von Gierke disease and
prevents hepatic glucose release during fasting.
4. A biopsy shows malignant cells containing abundant rough
endoplasmic reticulum and Golgi apparatus. Which function is
most increased in these cells?
A. Steroid synthesis
B. Protein secretion
,C. ATP production
D. Lipid storage
Answer: B. Protein secretion
Rationale: Rough ER and Golgi apparatus are involved in synthesis
and processing of secreted proteins. Cells specialized for protein
production contain extensive amounts of these organelles.
5. A patient develops hemolytic anemia after taking an oxidative
medication. Testing reveals decreased activity of glucose-6-
phosphate dehydrogenase. Which molecule is deficient?
A. NADPH
B. ATP
C. FADH2
D. Acetyl-CoA
Answer: A. NADPH
Rationale: G6PD generates NADPH through the pentose phosphate
pathway. NADPH maintains glutathione in its reduced form,
protecting red blood cells from oxidative damage.
6. A patient has damage to the left recurrent laryngeal nerve. Which
structure is most likely affected?
A. Tongue sensation
B. Vocal cord movement
C. Facial expression
D. Shoulder elevation
Answer: B. Vocal cord movement
, Rationale: The recurrent laryngeal nerve supplies most intrinsic
muscles of the larynx. Injury causes hoarseness due to impaired vocal
cord function.
7. A mutation prevents formation of microtubules. Which cellular
process is most directly impaired?
A. DNA replication
B. Chromosome separation
C. Protein folding
D. Lipid synthesis
Answer: B. Chromosome separation
Rationale: Microtubules form the mitotic spindle required for
chromosome movement during mitosis. Defects impair cell division.
8. A patient with hyperthyroidism has increased metabolic rate.
Which hormone directly increases transcription of mitochondrial
proteins?
A. Insulin
B. Thyroxine (T4)
C. Cortisol
D. Aldosterone
Answer: B. Thyroxine (T4)
Rationale: Thyroid hormone enters cells and binds nuclear receptors,
increasing transcription of genes involved in mitochondrial activity
and metabolism.
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 24-year-old man presents with recurrent infections involving
encapsulated bacteria. Laboratory testing reveals absence of
mature B cells due to a mutation affecting Bruton tyrosine kinase
(BTK). Which immune function is most directly impaired?
A. Activation of macrophages by interferon-gamma
B. Production of antibodies by plasma cells
C. Cytotoxic killing by CD8+ lymphocytes
D. Complement activation through the alternative pathway
Answer: B. Production of antibodies by plasma cells
Rationale: Bruton agammaglobulinemia results from defective B-cell
maturation due to BTK mutation. Without mature B cells, plasma cell
formation and immunoglobulin production are severely reduced,
leading to recurrent infections with encapsulated organisms.
2. A researcher studies a drug that blocks voltage-gated sodium
channels in neurons. Which phase of the action potential is
primarily affected?
,A. Resting membrane potential
B. Rapid depolarization phase
C. Repolarization phase
D. After-hyperpolarization phase
Answer: B. Rapid depolarization phase
Rationale: Voltage-gated sodium channels open during phase 0 of the
neuronal action potential, causing rapid sodium influx and
depolarization. Blocking these channels prevents initiation and
propagation of action potentials.
3. A patient with severe fasting hypoglycemia is found to have a
defect in glucose-6-phosphatase. Which metabolic process is
impaired?
A. Glycolysis
B. Glycogen synthesis
C. Release of glucose from the liver
D. Fatty acid oxidation
Answer: C. Release of glucose from the liver
Rationale: Glucose-6-phosphatase converts glucose-6-phosphate into
free glucose in hepatocytes. Deficiency causes von Gierke disease and
prevents hepatic glucose release during fasting.
4. A biopsy shows malignant cells containing abundant rough
endoplasmic reticulum and Golgi apparatus. Which function is
most increased in these cells?
A. Steroid synthesis
B. Protein secretion
,C. ATP production
D. Lipid storage
Answer: B. Protein secretion
Rationale: Rough ER and Golgi apparatus are involved in synthesis
and processing of secreted proteins. Cells specialized for protein
production contain extensive amounts of these organelles.
5. A patient develops hemolytic anemia after taking an oxidative
medication. Testing reveals decreased activity of glucose-6-
phosphate dehydrogenase. Which molecule is deficient?
A. NADPH
B. ATP
C. FADH2
D. Acetyl-CoA
Answer: A. NADPH
Rationale: G6PD generates NADPH through the pentose phosphate
pathway. NADPH maintains glutathione in its reduced form,
protecting red blood cells from oxidative damage.
6. A patient has damage to the left recurrent laryngeal nerve. Which
structure is most likely affected?
A. Tongue sensation
B. Vocal cord movement
C. Facial expression
D. Shoulder elevation
Answer: B. Vocal cord movement
, Rationale: The recurrent laryngeal nerve supplies most intrinsic
muscles of the larynx. Injury causes hoarseness due to impaired vocal
cord function.
7. A mutation prevents formation of microtubules. Which cellular
process is most directly impaired?
A. DNA replication
B. Chromosome separation
C. Protein folding
D. Lipid synthesis
Answer: B. Chromosome separation
Rationale: Microtubules form the mitotic spindle required for
chromosome movement during mitosis. Defects impair cell division.
8. A patient with hyperthyroidism has increased metabolic rate.
Which hormone directly increases transcription of mitochondrial
proteins?
A. Insulin
B. Thyroxine (T4)
C. Cortisol
D. Aldosterone
Answer: B. Thyroxine (T4)
Rationale: Thyroid hormone enters cells and binds nuclear receptors,
increasing transcription of genes involved in mitochondrial activity
and metabolism.
