COMSAE Phase 1 Form ASA 101
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 23-year-old osteopathic medical student is studying membrane
transport. A patient with cystic fibrosis has a mutation affecting
chloride transport across epithelial cells. Which transport
mechanism is directly impaired?
A. Simple diffusion
B. Primary active transport
C. Facilitated diffusion through an ion channel
D. Secondary active transport
Answer: C. Facilitated diffusion through an ion channel
Rationale: The CFTR protein functions as an ATP-regulated chloride
channel. Although ATP regulates channel opening, chloride movement
occurs down its electrochemical gradient through facilitated diffusion.
Defective CFTR leads to thick secretions in multiple organ systems.
2. A researcher inhibits pyruvate dehydrogenase in cultured cells.
Which metabolic consequence is most likely?
A. Increased acetyl-CoA production
B. Increased conversion of pyruvate to lactate
C. Increased β-oxidation inhibition
D. Increased gluconeogenesis inhibition
Answer: B. Increased conversion of pyruvate to lactate
,Rationale: Pyruvate dehydrogenase converts pyruvate into acetyl-CoA.
When inhibited, pyruvate accumulates and is diverted toward lactate
production through lactate dehydrogenase, increasing the risk of lactic
acidosis.
3. A newborn develops severe jaundice due to impaired bilirubin
conjugation. Which enzyme is deficient?
A. Heme oxygenase
B. Biliverdin reductase
C. UDP-glucuronosyltransferase
D. Glucose-6-phosphatase
Answer: C. UDP-glucuronosyltransferase
Rationale: UDP-glucuronosyltransferase conjugates bilirubin within
hepatocytes. Deficiency results in unconjugated hyperbilirubinemia as
seen in Crigler-Najjar syndrome and severe forms of neonatal jaundice.
4. A patient develops muscle weakness after receiving a
neuromuscular blocker. Which receptor is directly antagonized?
A. Muscarinic M2 receptor
B. Nicotinic Nm receptor
C. β1 receptor
D. α1 receptor
Answer: B. Nicotinic Nm receptor
Rationale: Nondepolarizing neuromuscular blockers competitively
inhibit nicotinic Nm receptors at the neuromuscular junction, preventing
skeletal muscle contraction.
5. A 67-year-old man experiences a stroke involving the left middle
cerebral artery. Which deficit is most likely?
,A. Left leg weakness
B. Right face and arm weakness
C. Bilateral visual loss
D. Right leg weakness only
Answer: B. Right face and arm weakness
Rationale: The middle cerebral artery supplies the lateral cerebral
cortex, including motor and sensory regions controlling the face and
upper extremity. Contralateral deficits result from corticospinal tract
involvement.
6. During exercise, skeletal muscle blood flow increases primarily
due to which local factor?
A. Endothelin release
B. Increased sympathetic tone
C. Adenosine accumulation
D. Elevated angiotensin II
Answer: C. Adenosine accumulation
Rationale: Active tissues generate vasodilatory metabolites such as
adenosine, CO₂, H⁺, and potassium, producing metabolic autoregulation
and increased perfusion.
7. Which microorganism lacks a cell wall and therefore is intrinsically
resistant to β-lactam antibiotics?
A. Streptococcus pneumoniae
B. Mycoplasma pneumoniae
C. Neisseria meningitidis
D. Haemophilus influenzae
Answer: B. Mycoplasma pneumoniae
, Rationale: Mycoplasma species lack peptidoglycan cell walls, rendering
β-lactam antibiotics ineffective because these drugs target cell wall
synthesis.
8. A patient with Graves disease exhibits excessive thyroid hormone
production. Which pituitary hormone level is expected?
A. Increased TSH
B. Normal TSH
C. Suppressed TSH
D. Elevated ACTH
Answer: C. Suppressed TSH
Rationale: Elevated thyroid hormone exerts negative feedback on the
hypothalamus and pituitary, resulting in markedly decreased TSH
secretion.
9. Which complement component acts as a potent neutrophil
chemotactic factor?
A. C1
B. C3b
C. C5a
D. C9
Answer: C. C5a
Rationale: C5a is one of the most powerful chemotactic mediators in
the complement cascade and recruits neutrophils to sites of
inflammation.
10. A patient develops nephrotic syndrome with selective
albumin loss. Which glomerular structure is primarily damaged?
A. Juxtaglomerular cells
B. Podocyte foot processes
Foundational Biomedical Sciences Exam
Practice Questions & [Verified Answers],
Plus Explained Rationales|2026 Latest
Update| Instant Download PDF
1. A 23-year-old osteopathic medical student is studying membrane
transport. A patient with cystic fibrosis has a mutation affecting
chloride transport across epithelial cells. Which transport
mechanism is directly impaired?
A. Simple diffusion
B. Primary active transport
C. Facilitated diffusion through an ion channel
D. Secondary active transport
Answer: C. Facilitated diffusion through an ion channel
Rationale: The CFTR protein functions as an ATP-regulated chloride
channel. Although ATP regulates channel opening, chloride movement
occurs down its electrochemical gradient through facilitated diffusion.
Defective CFTR leads to thick secretions in multiple organ systems.
2. A researcher inhibits pyruvate dehydrogenase in cultured cells.
Which metabolic consequence is most likely?
A. Increased acetyl-CoA production
B. Increased conversion of pyruvate to lactate
C. Increased β-oxidation inhibition
D. Increased gluconeogenesis inhibition
Answer: B. Increased conversion of pyruvate to lactate
,Rationale: Pyruvate dehydrogenase converts pyruvate into acetyl-CoA.
When inhibited, pyruvate accumulates and is diverted toward lactate
production through lactate dehydrogenase, increasing the risk of lactic
acidosis.
3. A newborn develops severe jaundice due to impaired bilirubin
conjugation. Which enzyme is deficient?
A. Heme oxygenase
B. Biliverdin reductase
C. UDP-glucuronosyltransferase
D. Glucose-6-phosphatase
Answer: C. UDP-glucuronosyltransferase
Rationale: UDP-glucuronosyltransferase conjugates bilirubin within
hepatocytes. Deficiency results in unconjugated hyperbilirubinemia as
seen in Crigler-Najjar syndrome and severe forms of neonatal jaundice.
4. A patient develops muscle weakness after receiving a
neuromuscular blocker. Which receptor is directly antagonized?
A. Muscarinic M2 receptor
B. Nicotinic Nm receptor
C. β1 receptor
D. α1 receptor
Answer: B. Nicotinic Nm receptor
Rationale: Nondepolarizing neuromuscular blockers competitively
inhibit nicotinic Nm receptors at the neuromuscular junction, preventing
skeletal muscle contraction.
5. A 67-year-old man experiences a stroke involving the left middle
cerebral artery. Which deficit is most likely?
,A. Left leg weakness
B. Right face and arm weakness
C. Bilateral visual loss
D. Right leg weakness only
Answer: B. Right face and arm weakness
Rationale: The middle cerebral artery supplies the lateral cerebral
cortex, including motor and sensory regions controlling the face and
upper extremity. Contralateral deficits result from corticospinal tract
involvement.
6. During exercise, skeletal muscle blood flow increases primarily
due to which local factor?
A. Endothelin release
B. Increased sympathetic tone
C. Adenosine accumulation
D. Elevated angiotensin II
Answer: C. Adenosine accumulation
Rationale: Active tissues generate vasodilatory metabolites such as
adenosine, CO₂, H⁺, and potassium, producing metabolic autoregulation
and increased perfusion.
7. Which microorganism lacks a cell wall and therefore is intrinsically
resistant to β-lactam antibiotics?
A. Streptococcus pneumoniae
B. Mycoplasma pneumoniae
C. Neisseria meningitidis
D. Haemophilus influenzae
Answer: B. Mycoplasma pneumoniae
, Rationale: Mycoplasma species lack peptidoglycan cell walls, rendering
β-lactam antibiotics ineffective because these drugs target cell wall
synthesis.
8. A patient with Graves disease exhibits excessive thyroid hormone
production. Which pituitary hormone level is expected?
A. Increased TSH
B. Normal TSH
C. Suppressed TSH
D. Elevated ACTH
Answer: C. Suppressed TSH
Rationale: Elevated thyroid hormone exerts negative feedback on the
hypothalamus and pituitary, resulting in markedly decreased TSH
secretion.
9. Which complement component acts as a potent neutrophil
chemotactic factor?
A. C1
B. C3b
C. C5a
D. C9
Answer: C. C5a
Rationale: C5a is one of the most powerful chemotactic mediators in
the complement cascade and recruits neutrophils to sites of
inflammation.
10. A patient develops nephrotic syndrome with selective
albumin loss. Which glomerular structure is primarily damaged?
A. Juxtaglomerular cells
B. Podocyte foot processes
