COMSAE PHASE 1 FORM 107I EXAM PRACTICE | COMPREHENSIVE STUDY GUIDE |
ADVANCED TESTBANK | PRACTICE QUESTIONS & ANSWERS | LATEST UPDATE
2026/2027
i. Biochemistry, Molecular Biology & Genetics
ii. Immunology, Microbiology & Infectious Disease
iii. Anatomy, Embryology & Histology
iv. Physiology & Pathophysiology
v. Pharmacology & Therapeutics
vi. Cardiovascular, Respiratory & Renal Systems
vii. Gastrointestinal, Endocrine & Reproductive Systems
viii. Neuroscience, Musculoskeletal & Behavioral Sciences
ix. Hematology, Oncology & Multisystem Disease
x. Clinical Integration, Ethics & Preventive Medicine
INTRODUCTION
This COMSAE Phase 1 Form 107i practice set emphasizes integrated foundational
biomedical science and clinical reasoning appropriate for advanced osteopathic
medical education. Questions span molecular mechanisms, anatomy, physiology,
pathology, microbiology, immunology, pharmacology, neuroscience, and organ-system
integration. The emphasis is on applying mechanisms to unfamiliar clinical scenarios
rather than recalling isolated facts. Students should expect questions requiring
interpretation of laboratory findings, physiologic relationships, pharmacologic effects,
disease mechanisms, and anatomical localization. The set is designed as a study
resource rather than a reproduction of any official examination. The 30 questions below
progressively emphasize high-yield concepts while incorporating challenging
distractors and clinically realistic decision-making.
Question 1
A 24-year-old man develops severe muscle cramps and dark urine after beginning an
intense exercise regimen. Laboratory studies show markedly elevated creatine kinase
and mild hyperkalemia. His symptoms have occurred intermittently since adolescence,
particularly after prolonged exercise or fasting. A muscle biopsy demonstrates
excessive accumulation of glycogen with relatively normal branching structure. Which
metabolic defect most likely explains this patient's condition?
A. Deficiency of glucose-6-phosphatase
B. Deficiency of muscle glycogen phosphorylase
,C. Deficiency of lysosomal acid α-glucosidase
D. Deficiency of branching enzyme
🔴 Correct Answer: B. Deficiency of muscle glycogen phosphorylase.
🔵 Explanation: McArdle disease results from muscle glycogen phosphorylase deficiency,
impairing glycogen breakdown during exercise. Patients develop exercise intolerance,
painful muscle cramps, and rhabdomyolysis. Glycogen structure remains relatively
normal, distinguishing it from branching-enzyme abnormalities.
Question 2
A researcher introduces a mutation into a gene encoding a membrane receptor. The
mutation changes one amino acid within the receptor's intracellular signaling domain
but does not alter ligand binding or receptor expression at the cell surface. Cells
expressing the mutant receptor demonstrate prolonged activation of downstream
signaling after ligand exposure. Which molecular mechanism most likely accounts for
this finding?
A. Increased transcription of the receptor gene
B. Impaired receptor internalization or signal termination
C. Reduced ligand affinity for the receptor
D. Failure of receptor translation
🔴 Correct Answer: B. Impaired receptor internalization or signal termination.
🔵 Explanation: A mutation in an intracellular signaling domain can preserve ligand
binding while disrupting mechanisms that terminate receptor signaling. Prolonged
downstream activation despite normal receptor expression and ligand binding is therefore
most consistent with impaired signal termination.
Question 3
A 67-year-old man with chronic hypertension develops progressive exertional dyspnea.
Echocardiography shows increased left ventricular wall thickness with preserved
ejection fraction. Which cellular adaptation is most directly responsible for the
increased myocardial mass?
A. Hyperplasia of cardiac myocytes
B. Hypertrophy of cardiac myocytes
C. Metaplasia of cardiac myocytes
D. Increased myocardial stem-cell differentiation
,🔴 Correct Answer: B. Hypertrophy of cardiac myocytes.
🔵 Explanation: Mature cardiac myocytes have limited proliferative capacity. Chronic
pressure overload therefore produces hypertrophy, characterized by enlargement of
individual myocytes and increased protein synthesis. Long-standing hypertension
commonly causes concentric left ventricular hypertrophy.
Question 4
A patient with severe vomiting for several days develops weakness and confusion.
Laboratory studies show pH 7.52, increased bicarbonate concentration, and decreased
serum chloride. Which renal response would most strongly perpetuate the patient's
acid-base disturbance?
A. Increased bicarbonate excretion
B. Increased hydrogen ion secretion
C. Decreased ammonium production
D. Increased chloride-independent bicarbonate secretion
🔴 Correct Answer: B. Increased hydrogen ion secretion.
🔵 Explanation: Persistent vomiting causes loss of gastric hydrochloric acid and produces
metabolic alkalosis. Volume contraction and chloride depletion promote renal hydrogen
ion secretion and bicarbonate retention, helping maintain the alkalosis.
Question 5
A 35-year-old woman develops proximal muscle weakness, hypertension, and
hypokalemia. Laboratory testing reveals elevated cortisol with suppressed ACTH.
Administration of dexamethasone produces little reduction in cortisol concentration. A
cortisol-secreting adrenal adenoma is suspected. Which biochemical property best
explains the patient's hypertension and hypokalemia?
A. Cortisol activates mineralocorticoid receptors when present at sufficiently high
concentrations
B. Cortisol directly stimulates renin release
C. Cortisol blocks epithelial sodium channels
D. Cortisol inhibits aldosterone synthesis while activating potassium secretion
🔴 Correct Answer: A. Cortisol activates mineralocorticoid receptors when present at
sufficiently high concentrations.
🔵 Explanation: At very high concentrations, cortisol can overwhelm renal 11β-
hydroxysteroid dehydrogenase type 2, allowing activation of mineralocorticoid receptors.
, This increases sodium retention and potassium and hydrogen ion secretion, producing
hypertension and hypokalemia.
Question 6
A 19-year-old college student presents with fever, headache, photophobia, and neck
stiffness. Cerebrospinal fluid demonstrates neutrophilic pleocytosis, markedly elevated
protein, and decreased glucose. Gram stain reveals gram-negative diplococci. Which
virulence factor most directly facilitates bloodstream survival by this organism?
A. M protein
B. Polysaccharide capsule
C. Protein A
D. Lipoteichoic acid
🔴 Correct Answer: B. Polysaccharide capsule.
🔵 Explanation: Neisseria meningitidis possesses a polysaccharide capsule that inhibits
phagocytosis and promotes survival in the bloodstream. Meningococcal meningitis
classically presents with acute fever, headache, meningismus, and neutrophilic CSF
findings.
Question 7
A 42-year-old woman develops recurrent sinus infections and chronic diarrhea.
Laboratory testing shows markedly decreased IgG, IgA, and IgM levels. B cells are
present in normal numbers but demonstrate impaired differentiation into plasma cells.
Which immunologic defect best explains this presentation?
A. Failure of thymic T-cell maturation
B. Defective B-cell terminal differentiation
C. Absence of complement component C3
D. Defective neutrophil oxidative burst
🔴 Correct Answer: B. Defective B-cell terminal differentiation.
🔵 Explanation: Common variable immunodeficiency is characterized by impaired
antibody production despite the presence of B cells. Defective differentiation into
functional plasma cells leads to recurrent sinopulmonary infections and gastrointestinal
infections.
Question 8
ADVANCED TESTBANK | PRACTICE QUESTIONS & ANSWERS | LATEST UPDATE
2026/2027
i. Biochemistry, Molecular Biology & Genetics
ii. Immunology, Microbiology & Infectious Disease
iii. Anatomy, Embryology & Histology
iv. Physiology & Pathophysiology
v. Pharmacology & Therapeutics
vi. Cardiovascular, Respiratory & Renal Systems
vii. Gastrointestinal, Endocrine & Reproductive Systems
viii. Neuroscience, Musculoskeletal & Behavioral Sciences
ix. Hematology, Oncology & Multisystem Disease
x. Clinical Integration, Ethics & Preventive Medicine
INTRODUCTION
This COMSAE Phase 1 Form 107i practice set emphasizes integrated foundational
biomedical science and clinical reasoning appropriate for advanced osteopathic
medical education. Questions span molecular mechanisms, anatomy, physiology,
pathology, microbiology, immunology, pharmacology, neuroscience, and organ-system
integration. The emphasis is on applying mechanisms to unfamiliar clinical scenarios
rather than recalling isolated facts. Students should expect questions requiring
interpretation of laboratory findings, physiologic relationships, pharmacologic effects,
disease mechanisms, and anatomical localization. The set is designed as a study
resource rather than a reproduction of any official examination. The 30 questions below
progressively emphasize high-yield concepts while incorporating challenging
distractors and clinically realistic decision-making.
Question 1
A 24-year-old man develops severe muscle cramps and dark urine after beginning an
intense exercise regimen. Laboratory studies show markedly elevated creatine kinase
and mild hyperkalemia. His symptoms have occurred intermittently since adolescence,
particularly after prolonged exercise or fasting. A muscle biopsy demonstrates
excessive accumulation of glycogen with relatively normal branching structure. Which
metabolic defect most likely explains this patient's condition?
A. Deficiency of glucose-6-phosphatase
B. Deficiency of muscle glycogen phosphorylase
,C. Deficiency of lysosomal acid α-glucosidase
D. Deficiency of branching enzyme
🔴 Correct Answer: B. Deficiency of muscle glycogen phosphorylase.
🔵 Explanation: McArdle disease results from muscle glycogen phosphorylase deficiency,
impairing glycogen breakdown during exercise. Patients develop exercise intolerance,
painful muscle cramps, and rhabdomyolysis. Glycogen structure remains relatively
normal, distinguishing it from branching-enzyme abnormalities.
Question 2
A researcher introduces a mutation into a gene encoding a membrane receptor. The
mutation changes one amino acid within the receptor's intracellular signaling domain
but does not alter ligand binding or receptor expression at the cell surface. Cells
expressing the mutant receptor demonstrate prolonged activation of downstream
signaling after ligand exposure. Which molecular mechanism most likely accounts for
this finding?
A. Increased transcription of the receptor gene
B. Impaired receptor internalization or signal termination
C. Reduced ligand affinity for the receptor
D. Failure of receptor translation
🔴 Correct Answer: B. Impaired receptor internalization or signal termination.
🔵 Explanation: A mutation in an intracellular signaling domain can preserve ligand
binding while disrupting mechanisms that terminate receptor signaling. Prolonged
downstream activation despite normal receptor expression and ligand binding is therefore
most consistent with impaired signal termination.
Question 3
A 67-year-old man with chronic hypertension develops progressive exertional dyspnea.
Echocardiography shows increased left ventricular wall thickness with preserved
ejection fraction. Which cellular adaptation is most directly responsible for the
increased myocardial mass?
A. Hyperplasia of cardiac myocytes
B. Hypertrophy of cardiac myocytes
C. Metaplasia of cardiac myocytes
D. Increased myocardial stem-cell differentiation
,🔴 Correct Answer: B. Hypertrophy of cardiac myocytes.
🔵 Explanation: Mature cardiac myocytes have limited proliferative capacity. Chronic
pressure overload therefore produces hypertrophy, characterized by enlargement of
individual myocytes and increased protein synthesis. Long-standing hypertension
commonly causes concentric left ventricular hypertrophy.
Question 4
A patient with severe vomiting for several days develops weakness and confusion.
Laboratory studies show pH 7.52, increased bicarbonate concentration, and decreased
serum chloride. Which renal response would most strongly perpetuate the patient's
acid-base disturbance?
A. Increased bicarbonate excretion
B. Increased hydrogen ion secretion
C. Decreased ammonium production
D. Increased chloride-independent bicarbonate secretion
🔴 Correct Answer: B. Increased hydrogen ion secretion.
🔵 Explanation: Persistent vomiting causes loss of gastric hydrochloric acid and produces
metabolic alkalosis. Volume contraction and chloride depletion promote renal hydrogen
ion secretion and bicarbonate retention, helping maintain the alkalosis.
Question 5
A 35-year-old woman develops proximal muscle weakness, hypertension, and
hypokalemia. Laboratory testing reveals elevated cortisol with suppressed ACTH.
Administration of dexamethasone produces little reduction in cortisol concentration. A
cortisol-secreting adrenal adenoma is suspected. Which biochemical property best
explains the patient's hypertension and hypokalemia?
A. Cortisol activates mineralocorticoid receptors when present at sufficiently high
concentrations
B. Cortisol directly stimulates renin release
C. Cortisol blocks epithelial sodium channels
D. Cortisol inhibits aldosterone synthesis while activating potassium secretion
🔴 Correct Answer: A. Cortisol activates mineralocorticoid receptors when present at
sufficiently high concentrations.
🔵 Explanation: At very high concentrations, cortisol can overwhelm renal 11β-
hydroxysteroid dehydrogenase type 2, allowing activation of mineralocorticoid receptors.
, This increases sodium retention and potassium and hydrogen ion secretion, producing
hypertension and hypokalemia.
Question 6
A 19-year-old college student presents with fever, headache, photophobia, and neck
stiffness. Cerebrospinal fluid demonstrates neutrophilic pleocytosis, markedly elevated
protein, and decreased glucose. Gram stain reveals gram-negative diplococci. Which
virulence factor most directly facilitates bloodstream survival by this organism?
A. M protein
B. Polysaccharide capsule
C. Protein A
D. Lipoteichoic acid
🔴 Correct Answer: B. Polysaccharide capsule.
🔵 Explanation: Neisseria meningitidis possesses a polysaccharide capsule that inhibits
phagocytosis and promotes survival in the bloodstream. Meningococcal meningitis
classically presents with acute fever, headache, meningismus, and neutrophilic CSF
findings.
Question 7
A 42-year-old woman develops recurrent sinus infections and chronic diarrhea.
Laboratory testing shows markedly decreased IgG, IgA, and IgM levels. B cells are
present in normal numbers but demonstrate impaired differentiation into plasma cells.
Which immunologic defect best explains this presentation?
A. Failure of thymic T-cell maturation
B. Defective B-cell terminal differentiation
C. Absence of complement component C3
D. Defective neutrophil oxidative burst
🔴 Correct Answer: B. Defective B-cell terminal differentiation.
🔵 Explanation: Common variable immunodeficiency is characterized by impaired
antibody production despite the presence of B cells. Defective differentiation into
functional plasma cells leads to recurrent sinopulmonary infections and gastrointestinal
infections.
Question 8
