COMSAE PHASE 1 FORM 113 — PRACTICE EXAM | STUDY GUIDE | TESTBANK | LATEST
UPDATE 2026/2027 | QUESTIONS & 100% CORRECT ANSWERS
Table of Contents
1. Anatomy and Embryology
2. Physiology and Homeostasis
3. Biochemistry and Molecular Biology
4. Microbiology and Immunology
5. Pathology and Pathophysiology
6. Pharmacology
7. Osteopathic Principles and Practice
8. Behavioral Science and Ethics
9. Clinical Reasoning and Patient Management
10. Epidemiology and Preventive Medicine
Introduction
The COMSAE Phase 1 examination assesses foundational biomedical sciences and their
application to clinical medicine at the level expected of osteopathic medical students
preparing for licensing examinations. Candidates must integrate knowledge from
anatomy, physiology, pathology, pharmacology, microbiology, biochemistry, behavioral
sciences, epidemiology, and osteopathic principles. Questions emphasize clinical
reasoning, interpretation of laboratory and diagnostic findings, patient-centered decision-
making, and application of scientific concepts to realistic scenarios. This practice
examination reflects the breadth and complexity commonly encountered on COMSAE-
,style assessments and is designed to strengthen critical thinking, diagnostic accuracy, and
readiness for advanced medical board examinations.
Question 1
A 62-year-old man develops resting tremor, bradykinesia, and rigidity. Degeneration of
neurons in which structure most directly causes these findings?
A. Caudate nucleus
B. Subthalamic nucleus
C. Substantia nigra pars compacta
D. Globus pallidus externus
Correct Answer: C
Explanation: Parkinson disease results primarily from loss of dopaminergic neurons in
the substantia nigra pars compacta, reducing stimulation of the direct pathway and
impairing movement.
Question 2
A patient with chronic diarrhea has metabolic acidosis. Which compensatory response is
expected?
A. Increased PaCO₂
B. Decreased respiratory rate
,C. Increased bicarbonate retention by the lungs
D. Decreased PaCO₂
Correct Answer: D
Explanation: Metabolic acidosis stimulates hyperventilation, lowering PaCO₂ and
partially correcting pH.
Question 3
A mutation causes defective nucleotide excision repair. Which condition is most likely?
A. Huntington disease
B. Xeroderma pigmentosum
C. Marfan syndrome
D. Tuberous sclerosis
Correct Answer: B
Explanation: Xeroderma pigmentosum results from impaired repair of UV-induced DNA
damage through defective nucleotide excision repair.
Question 4
A patient develops fever and productive cough. Histology reveals numerous neutrophils
within alveoli. Which cytokine is most responsible for neutrophil recruitment?
, A. IL-8
B. IL-4
C. IL-10
D. TGF-β
Correct Answer: A
Explanation: IL-8 is a major chemotactic factor directing neutrophil migration to sites of
infection.
Question 5
A 45-year-old woman presents with fatigue and elevated TSH. Autoantibodies against
thyroid peroxidase are detected. What is the diagnosis?
A. Graves disease
B. Hashimoto thyroiditis
C. Subacute thyroiditis
D. Toxic multinodular goiter
Correct Answer: B
Explanation: Anti-thyroid peroxidase antibodies are strongly associated with Hashimoto
thyroiditis.
UPDATE 2026/2027 | QUESTIONS & 100% CORRECT ANSWERS
Table of Contents
1. Anatomy and Embryology
2. Physiology and Homeostasis
3. Biochemistry and Molecular Biology
4. Microbiology and Immunology
5. Pathology and Pathophysiology
6. Pharmacology
7. Osteopathic Principles and Practice
8. Behavioral Science and Ethics
9. Clinical Reasoning and Patient Management
10. Epidemiology and Preventive Medicine
Introduction
The COMSAE Phase 1 examination assesses foundational biomedical sciences and their
application to clinical medicine at the level expected of osteopathic medical students
preparing for licensing examinations. Candidates must integrate knowledge from
anatomy, physiology, pathology, pharmacology, microbiology, biochemistry, behavioral
sciences, epidemiology, and osteopathic principles. Questions emphasize clinical
reasoning, interpretation of laboratory and diagnostic findings, patient-centered decision-
making, and application of scientific concepts to realistic scenarios. This practice
examination reflects the breadth and complexity commonly encountered on COMSAE-
,style assessments and is designed to strengthen critical thinking, diagnostic accuracy, and
readiness for advanced medical board examinations.
Question 1
A 62-year-old man develops resting tremor, bradykinesia, and rigidity. Degeneration of
neurons in which structure most directly causes these findings?
A. Caudate nucleus
B. Subthalamic nucleus
C. Substantia nigra pars compacta
D. Globus pallidus externus
Correct Answer: C
Explanation: Parkinson disease results primarily from loss of dopaminergic neurons in
the substantia nigra pars compacta, reducing stimulation of the direct pathway and
impairing movement.
Question 2
A patient with chronic diarrhea has metabolic acidosis. Which compensatory response is
expected?
A. Increased PaCO₂
B. Decreased respiratory rate
,C. Increased bicarbonate retention by the lungs
D. Decreased PaCO₂
Correct Answer: D
Explanation: Metabolic acidosis stimulates hyperventilation, lowering PaCO₂ and
partially correcting pH.
Question 3
A mutation causes defective nucleotide excision repair. Which condition is most likely?
A. Huntington disease
B. Xeroderma pigmentosum
C. Marfan syndrome
D. Tuberous sclerosis
Correct Answer: B
Explanation: Xeroderma pigmentosum results from impaired repair of UV-induced DNA
damage through defective nucleotide excision repair.
Question 4
A patient develops fever and productive cough. Histology reveals numerous neutrophils
within alveoli. Which cytokine is most responsible for neutrophil recruitment?
, A. IL-8
B. IL-4
C. IL-10
D. TGF-β
Correct Answer: A
Explanation: IL-8 is a major chemotactic factor directing neutrophil migration to sites of
infection.
Question 5
A 45-year-old woman presents with fatigue and elevated TSH. Autoantibodies against
thyroid peroxidase are detected. What is the diagnosis?
A. Graves disease
B. Hashimoto thyroiditis
C. Subacute thyroiditis
D. Toxic multinodular goiter
Correct Answer: B
Explanation: Anti-thyroid peroxidase antibodies are strongly associated with Hashimoto
thyroiditis.
