COMSAE Phase 1 Form ASA 118
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 22-year-old man develops fatigue, jaundice, and dark urine after
taking a medication that causes oxidative stress. Laboratory studies
reveal hemolytic anemia. A deficiency in which enzyme is most likely
responsible?
A. Pyruvate kinase
B. Glucose-6-phosphate dehydrogenase
C. Hexokinase
D. Lactate dehydrogenase
E. Phosphofructokinase
Answer: B. Glucose-6-phosphate dehydrogenase
Rationale: Glucose-6-phosphate dehydrogenase deficiency decreases
NADPH production through the pentose phosphate pathway. Reduced
NADPH impairs glutathione regeneration, leaving RBCs vulnerable to
oxidative damage and causing episodic hemolysis after oxidative
stress.
2. A patient with hyperthyroidism has increased production of thyroid
hormones. Which cellular process is directly increased?
,A. DNA replication
B. Protein translation
C. Glycogen breakdown
D. RNA degradation
E. Lipid storage
Answer: B. Protein translation
Rationale: Thyroid hormones increase basal metabolic activity by
increasing gene transcription and protein synthesis. They enhance
mitochondrial activity and cellular metabolism.
3. A mutation causes failure of lysosomal enzymes to be transported
into lysosomes. Which organelle process is defective?
A. Nuclear import
B. Golgi sorting
C. Ribosomal assembly
D. Mitochondrial transport
E. Peroxisomal oxidation
Answer: B. Golgi sorting
Rationale: Lysosomal enzymes are tagged with mannose-6-phosphate
in the Golgi apparatus. Defects in this pathway cause inclusion-cell
disease (I-cell disease).
4. A patient develops a lesion affecting the corticospinal tract. Which
finding is expected?
A. Loss of vibration sensation
B. Flaccid paralysis
C. Hyperreflexia
,D. Loss of pain sensation
E. Muscle atrophy only
Answer: C. Hyperreflexia
Rationale: Upper motor neuron lesions affecting corticospinal
pathways cause increased tone, hyperreflexia, and spastic weakness
due to loss of inhibitory descending control.
5. A bacterial strain becomes resistant to an antibiotic by acquiring a
plasmid. This occurs through:
A. Binary fission
B. Transduction
C. Conjugation
D. Sporulation
E. Mutation repair
Answer: C. Conjugation
Rationale: Conjugation involves transfer of plasmid DNA between
bacteria through direct cell-to-cell contact using a pilus.
6. A patient with chronic alcohol use develops confusion, ataxia, and
ophthalmoplegia. Which vitamin deficiency is responsible?
A. Vitamin B1
B. Vitamin B6
C. Vitamin B12
D. Vitamin C
E. Vitamin K
Answer: A. Vitamin B1
, Rationale: Thiamine deficiency causes Wernicke encephalopathy.
Thiamine is required for pyruvate dehydrogenase and alpha-
ketoglutarate dehydrogenase activity.
7. A patient has decreased secretion of hydrochloric acid from gastric
parietal cells. Which vitamin absorption is impaired?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D
E. Vitamin E
Answer: B. Vitamin B12
Rationale: Gastric acid helps release vitamin B12 from food proteins.
Parietal cells also produce intrinsic factor required for B12 absorption
in the terminal ileum.
8. A mutation affects collagen synthesis. Which amino acid
modification is impaired?
A. Glycosylation only
B. Hydroxylation of proline and lysine
C. Phosphorylation of tyrosine
D. Methylation of DNA
E. Acetylation of histones
Answer: B. Hydroxylation of proline and lysine
Rationale: Vitamin C is required for hydroxylation of proline and lysine
residues during collagen formation. Deficiency causes impaired
connective tissue stability.
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 22-year-old man develops fatigue, jaundice, and dark urine after
taking a medication that causes oxidative stress. Laboratory studies
reveal hemolytic anemia. A deficiency in which enzyme is most likely
responsible?
A. Pyruvate kinase
B. Glucose-6-phosphate dehydrogenase
C. Hexokinase
D. Lactate dehydrogenase
E. Phosphofructokinase
Answer: B. Glucose-6-phosphate dehydrogenase
Rationale: Glucose-6-phosphate dehydrogenase deficiency decreases
NADPH production through the pentose phosphate pathway. Reduced
NADPH impairs glutathione regeneration, leaving RBCs vulnerable to
oxidative damage and causing episodic hemolysis after oxidative
stress.
2. A patient with hyperthyroidism has increased production of thyroid
hormones. Which cellular process is directly increased?
,A. DNA replication
B. Protein translation
C. Glycogen breakdown
D. RNA degradation
E. Lipid storage
Answer: B. Protein translation
Rationale: Thyroid hormones increase basal metabolic activity by
increasing gene transcription and protein synthesis. They enhance
mitochondrial activity and cellular metabolism.
3. A mutation causes failure of lysosomal enzymes to be transported
into lysosomes. Which organelle process is defective?
A. Nuclear import
B. Golgi sorting
C. Ribosomal assembly
D. Mitochondrial transport
E. Peroxisomal oxidation
Answer: B. Golgi sorting
Rationale: Lysosomal enzymes are tagged with mannose-6-phosphate
in the Golgi apparatus. Defects in this pathway cause inclusion-cell
disease (I-cell disease).
4. A patient develops a lesion affecting the corticospinal tract. Which
finding is expected?
A. Loss of vibration sensation
B. Flaccid paralysis
C. Hyperreflexia
,D. Loss of pain sensation
E. Muscle atrophy only
Answer: C. Hyperreflexia
Rationale: Upper motor neuron lesions affecting corticospinal
pathways cause increased tone, hyperreflexia, and spastic weakness
due to loss of inhibitory descending control.
5. A bacterial strain becomes resistant to an antibiotic by acquiring a
plasmid. This occurs through:
A. Binary fission
B. Transduction
C. Conjugation
D. Sporulation
E. Mutation repair
Answer: C. Conjugation
Rationale: Conjugation involves transfer of plasmid DNA between
bacteria through direct cell-to-cell contact using a pilus.
6. A patient with chronic alcohol use develops confusion, ataxia, and
ophthalmoplegia. Which vitamin deficiency is responsible?
A. Vitamin B1
B. Vitamin B6
C. Vitamin B12
D. Vitamin C
E. Vitamin K
Answer: A. Vitamin B1
, Rationale: Thiamine deficiency causes Wernicke encephalopathy.
Thiamine is required for pyruvate dehydrogenase and alpha-
ketoglutarate dehydrogenase activity.
7. A patient has decreased secretion of hydrochloric acid from gastric
parietal cells. Which vitamin absorption is impaired?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin D
E. Vitamin E
Answer: B. Vitamin B12
Rationale: Gastric acid helps release vitamin B12 from food proteins.
Parietal cells also produce intrinsic factor required for B12 absorption
in the terminal ileum.
8. A mutation affects collagen synthesis. Which amino acid
modification is impaired?
A. Glycosylation only
B. Hydroxylation of proline and lysine
C. Phosphorylation of tyrosine
D. Methylation of DNA
E. Acetylation of histones
Answer: B. Hydroxylation of proline and lysine
Rationale: Vitamin C is required for hydroxylation of proline and lysine
residues during collagen formation. Deficiency causes impaired
connective tissue stability.
