COMSAE Phase 1 Form 113 Practice Exam Questions
And Correct Answers (Verified Answers) Plus
Rationales 2025|2026 Q&A | Instant Download PDF
Question 1
Which of the following is NOT a component of the basal ganglia?
• A. Caudate nucleus
• B. Putamen
• C. Globus pallidus
• D. Red nucleus
Rationale: The basal ganglia consist of the caudate, putamen, globus pallidus,
subthalamic nucleus, and substantia nigra. The red nucleus is part of the midbrain
and is involved in motor coordination but is not considered a basal ganglion
component.
Question 2
Which amino acid is both ketogenic and glucogenic?
• A. Leucine
• B. Lysine
• C. Phenylalanine
• D. Valine
Rationale: Phenylalanine is both ketogenic and glucogenic. Leucine and lysine are
purely ketogenic. Valine is purely glucogenic.
Question 3
,A 55-year-old male presents with chest pain radiating to the jaw, diaphoresis, and
nausea. ECG shows ST-segment elevation in leads V1-V4. Which coronary artery
is most likely occluded?
• A. Right coronary artery
• B. Left circumflex artery
• C. Left anterior descending artery
• D. Posterior descending artery
Rationale: ST elevation in V1-V4 indicates anterior wall myocardial infarction,
typically caused by occlusion of the left anterior descending (LAD) artery.
Question 4
A Gram-negative, oxidase-positive, curved rod is isolated from a patient with
watery diarrhea after eating raw oysters. What is the most likely organism?
• A. Escherichia coli
• B. Salmonella typhi
• C. Vibrio cholerae
• D. Campylobacter jejuni
Rationale: Vibrio cholerae is a Gram-negative, oxidase-positive, curved rod
associated with raw shellfish consumption and causes profuse watery diarrhea.
Question 5
Which part of the nephron is impermeable to water in the absence of antidiuretic
hormone (ADH)?
• A. Proximal convoluted tubule
• B. Descending loop of Henle
• C. Collecting duct
• D. Ascending loop of Henle
,Rationale: The collecting duct is impermeable to water without ADH. ADH
inserts aquaporin-2 channels to increase water reabsorption.
Question 6
In the citric acid cycle, which enzyme catalyzes the conversion of isocitrate to α-
ketoglutarate?
• A. Aconitase
• B. Isocitrate dehydrogenase
• C. α-Ketoglutarate dehydrogenase
• D. Succinate dehydrogenase
Rationale: Isocitrate dehydrogenase converts isocitrate to α-ketoglutarate,
producing NADH and CO₂. This is a rate-limiting step of the TCA cycle.
Question 7
A patient with a history of alcoholism presents with nystagmus, ataxia, and
confusion. Which vitamin deficiency is most likely?
• A. Thiamine (B1)
• B. Riboflavin (B2)
• C. Niacin (B3)
• D. Pyridoxine (B6)
Rationale: Wernicke encephalopathy (nystagmus, ataxia, confusion) is caused by
thiamine deficiency, common in alcoholics.
Question 8
Which cranial nerve provides parasympathetic innervation to the parotid gland?
• A. Facial nerve (CN VII)
• B. Glossopharyngeal nerve (CN IX)
, • C. Vagus nerve (CN X)
• D. Trigeminal nerve (CN V)
Rationale: The glossopharyngeal nerve (CN IX) carries parasympathetic fibers via
the otic ganglion to the parotid gland for salivation.
Question 9
Which class of lupus nephritis is characterized by diffuse proliferative
glomerulonephritis with wire-loop lesions?
• A. Class II (mesangial)
• B. Class III (focal)
• C. Class IV (diffuse)
• D. Class V (membranous)
Rationale: Class IV lupus nephritis (diffuse proliferative) shows wire-loop
capillary wall thickening due to subendothelial immune complex deposition.
Question 10
Which medication inhibits the HMG-CoA reductase enzyme?
• A. Ezetimibe
• B. Atorvastatin
• C. Niacin
• D. Gemfibrozil
Rationale: Statins (e.g., atorvastatin) competitively inhibit HMG-CoA reductase,
the rate-limiting enzyme in cholesterol synthesis.
Question 11
And Correct Answers (Verified Answers) Plus
Rationales 2025|2026 Q&A | Instant Download PDF
Question 1
Which of the following is NOT a component of the basal ganglia?
• A. Caudate nucleus
• B. Putamen
• C. Globus pallidus
• D. Red nucleus
Rationale: The basal ganglia consist of the caudate, putamen, globus pallidus,
subthalamic nucleus, and substantia nigra. The red nucleus is part of the midbrain
and is involved in motor coordination but is not considered a basal ganglion
component.
Question 2
Which amino acid is both ketogenic and glucogenic?
• A. Leucine
• B. Lysine
• C. Phenylalanine
• D. Valine
Rationale: Phenylalanine is both ketogenic and glucogenic. Leucine and lysine are
purely ketogenic. Valine is purely glucogenic.
Question 3
,A 55-year-old male presents with chest pain radiating to the jaw, diaphoresis, and
nausea. ECG shows ST-segment elevation in leads V1-V4. Which coronary artery
is most likely occluded?
• A. Right coronary artery
• B. Left circumflex artery
• C. Left anterior descending artery
• D. Posterior descending artery
Rationale: ST elevation in V1-V4 indicates anterior wall myocardial infarction,
typically caused by occlusion of the left anterior descending (LAD) artery.
Question 4
A Gram-negative, oxidase-positive, curved rod is isolated from a patient with
watery diarrhea after eating raw oysters. What is the most likely organism?
• A. Escherichia coli
• B. Salmonella typhi
• C. Vibrio cholerae
• D. Campylobacter jejuni
Rationale: Vibrio cholerae is a Gram-negative, oxidase-positive, curved rod
associated with raw shellfish consumption and causes profuse watery diarrhea.
Question 5
Which part of the nephron is impermeable to water in the absence of antidiuretic
hormone (ADH)?
• A. Proximal convoluted tubule
• B. Descending loop of Henle
• C. Collecting duct
• D. Ascending loop of Henle
,Rationale: The collecting duct is impermeable to water without ADH. ADH
inserts aquaporin-2 channels to increase water reabsorption.
Question 6
In the citric acid cycle, which enzyme catalyzes the conversion of isocitrate to α-
ketoglutarate?
• A. Aconitase
• B. Isocitrate dehydrogenase
• C. α-Ketoglutarate dehydrogenase
• D. Succinate dehydrogenase
Rationale: Isocitrate dehydrogenase converts isocitrate to α-ketoglutarate,
producing NADH and CO₂. This is a rate-limiting step of the TCA cycle.
Question 7
A patient with a history of alcoholism presents with nystagmus, ataxia, and
confusion. Which vitamin deficiency is most likely?
• A. Thiamine (B1)
• B. Riboflavin (B2)
• C. Niacin (B3)
• D. Pyridoxine (B6)
Rationale: Wernicke encephalopathy (nystagmus, ataxia, confusion) is caused by
thiamine deficiency, common in alcoholics.
Question 8
Which cranial nerve provides parasympathetic innervation to the parotid gland?
• A. Facial nerve (CN VII)
• B. Glossopharyngeal nerve (CN IX)
, • C. Vagus nerve (CN X)
• D. Trigeminal nerve (CN V)
Rationale: The glossopharyngeal nerve (CN IX) carries parasympathetic fibers via
the otic ganglion to the parotid gland for salivation.
Question 9
Which class of lupus nephritis is characterized by diffuse proliferative
glomerulonephritis with wire-loop lesions?
• A. Class II (mesangial)
• B. Class III (focal)
• C. Class IV (diffuse)
• D. Class V (membranous)
Rationale: Class IV lupus nephritis (diffuse proliferative) shows wire-loop
capillary wall thickening due to subendothelial immune complex deposition.
Question 10
Which medication inhibits the HMG-CoA reductase enzyme?
• A. Ezetimibe
• B. Atorvastatin
• C. Niacin
• D. Gemfibrozil
Rationale: Statins (e.g., atorvastatin) competitively inhibit HMG-CoA reductase,
the rate-limiting enzyme in cholesterol synthesis.
Question 11
