NBME CBSE ACTUAL TEST QUESTIONS AND
ANSWERS 2026/2027 (QUIZ BANK WITH ALL THE
CORRECT ANSWERS) (USMLE STEP 1) MEDICAL
EXAMINATION
This comprehensive practice examination is meticulously designed for candidates preparing for
the NBME Comprehensive Basic Science Examination (CBSE) and the USMLE Step 1. Aligned
with the 2026/2027 curriculum, this document serves as a definitive study guide and exam
review, featuring 100 super-advanced questions that mirror the complexity and rigor of the
actual certification examination. It covers both theoretical foundations and clinical applications,
including anatomy, biochemistry, microbiology, pathology, pharmacology, physiology,
behavioral sciences, and biostatistics. Each question is accompanied by a detailed, verified
solution to ensure 100% correct answers and a deep, integrated understanding of basic science
principles, guaranteeing distinction-level preparation for this critical medical credential.
Table of Contents
1. Cardiovascular Physiology and Pathology
2. Pulmonary and Renal Physiology
3. Gastrointestinal and Hepatobiliary Systems
4. Endocrine and Reproductive Systems
5. Neurology and Musculoskeletal Systems
6. Microbiology and Immunology
7. Pharmacology and Toxicology
8. Biochemistry and Genetics
9. Pathology and Neoplasia
10. Behavioral Sciences, Biostatistics, and Ethics
,Question 1
A 55-year-old man with a history of hypertension presents with chest pain radiating to his left
arm. An ECG shows ST-segment elevation in leads V1-V4. Which coronary artery is most likely
occluded?
A) Left anterior descending artery
B) Right coronary artery
C) Left circumflex artery
D) Posterior descending artery
Correct Answer: A
ST-segment elevation in leads V1-V4 indicates an anterior wall myocardial infarction, which is
most commonly caused by occlusion of the left anterior descending (LAD) artery. The LAD
supplies the anterior wall of the left ventricle and the interventricular septum. The right
coronary artery (B) typically causes inferior wall MI (leads II, III, aVF), the left circumflex
artery (C) causes lateral wall MI (leads I, aVL, V5-V6), and the posterior descending artery (D)
is a branch of the RCA or LCX.
Question 2
A 68-year-old woman with a history of congestive heart failure is prescribed digoxin. She
presents with nausea, vomiting, and yellow vision. Which electrolyte abnormality is most likely
contributing to her symptoms?
A) Hyperkalemia
B) Hypokalemia
C) Hypermagnesemia
D) Hypocalcemia
Correct Answer: B
Digoxin toxicity is potentiated by hypokalemia. Hypokalemia increases the binding of digoxin to
cardiac sodium-potassium ATPase pumps, leading to increased toxicity. Symptoms of digoxin
toxicity include gastrointestinal distress (nausea, vomiting), visual disturbances (yellow vision,
halos), and cardiac arrhythmias. Hyperkalemia (A) is associated with digoxin toxicity but is a
,result, not a predisposing factor. Hypermagnesemia (C) and hypocalcemia (D) are less
commonly associated with digoxin toxicity.
Question 3
A 72-year-old man with a history of smoking presents with progressive shortness of breath and a
chronic cough. Pulmonary function tests show a decreased FEV1/FVC ratio and increased total
lung capacity. Which of the following best describes the underlying pathophysiology?
A) Destruction of alveolar walls and loss of elastic recoil
B) Thickening of the alveolar basement membrane
C) Inflammation and fibrosis of the bronchial walls
D) Excessive mucus production and airway obstruction
Correct Answer: A
The patient's presentation and pulmonary function tests are consistent with emphysema, a type of
COPD characterized by destruction of alveolar walls and loss of elastic recoil. This leads to
airway collapse during expiration, air trapping, and increased total lung capacity. The
decreased FEV1/FVC ratio indicates obstructive lung disease. Option B describes restrictive
lung disease, option C describes chronic bronchitis, and option D is also characteristic of
chronic bronchitis.
Question 4
A 45-year-old man with a history of alcohol abuse presents with jaundice, ascites, and confusion.
Laboratory findings show elevated AST and ALT with an AST/ALT ratio >2. Which of the
following is the most likely diagnosis?
A) Alcoholic hepatitis
B) Viral hepatitis
C) Nonalcoholic fatty liver disease
D) Primary biliary cirrhosis
Correct Answer: A
Alcoholic hepatitis is characterized by jaundice, ascites, and hepatic encephalopathy
, (confusion). The AST/ALT ratio >2 is classic for alcoholic liver disease, as AST is often elevated
more than ALT due to mitochondrial damage and pyridoxal phosphate depletion. Viral hepatitis
(B) typically has ALT > AST, nonalcoholic fatty liver disease (C) usually has a ratio <1, and
primary biliary cirrhosis (D) is an autoimmune disease with elevated alkaline phosphatase and
anti-mitochondrial antibodies.
Question 5
A 28-year-old woman presents with fatigue, weight gain, and cold intolerance. Laboratory
findings show elevated TSH and low free T4. Which of the following is the most likely cause?
A) Hashimoto's thyroiditis
B) Graves' disease
C) Subacute thyroiditis
D) Pituitary adenoma
Correct Answer: A
Hashimoto's thyroiditis is the most common cause of hypothyroidism, characterized by elevated
TSH and low free T4. This autoimmune condition results in destruction of the thyroid gland.
Graves' disease (B) is a cause of hyperthyroidism with low TSH and high T4. Subacute
thyroiditis (C) typically presents with a painful thyroid and transient hyperthyroidism. A
pituitary adenoma (D) secreting TSH would cause elevated TSH and elevated T4.
Question 6
A 60-year-old man with a history of diabetes presents with a non-healing ulcer on his right foot.
The ulcer is painless and located over the first metatarsal head. Which of the following is the
most likely underlying cause?
A) Peripheral neuropathy
B) Peripheral arterial disease
C) Venous insufficiency
D) Pressure ulcer
ANSWERS 2026/2027 (QUIZ BANK WITH ALL THE
CORRECT ANSWERS) (USMLE STEP 1) MEDICAL
EXAMINATION
This comprehensive practice examination is meticulously designed for candidates preparing for
the NBME Comprehensive Basic Science Examination (CBSE) and the USMLE Step 1. Aligned
with the 2026/2027 curriculum, this document serves as a definitive study guide and exam
review, featuring 100 super-advanced questions that mirror the complexity and rigor of the
actual certification examination. It covers both theoretical foundations and clinical applications,
including anatomy, biochemistry, microbiology, pathology, pharmacology, physiology,
behavioral sciences, and biostatistics. Each question is accompanied by a detailed, verified
solution to ensure 100% correct answers and a deep, integrated understanding of basic science
principles, guaranteeing distinction-level preparation for this critical medical credential.
Table of Contents
1. Cardiovascular Physiology and Pathology
2. Pulmonary and Renal Physiology
3. Gastrointestinal and Hepatobiliary Systems
4. Endocrine and Reproductive Systems
5. Neurology and Musculoskeletal Systems
6. Microbiology and Immunology
7. Pharmacology and Toxicology
8. Biochemistry and Genetics
9. Pathology and Neoplasia
10. Behavioral Sciences, Biostatistics, and Ethics
,Question 1
A 55-year-old man with a history of hypertension presents with chest pain radiating to his left
arm. An ECG shows ST-segment elevation in leads V1-V4. Which coronary artery is most likely
occluded?
A) Left anterior descending artery
B) Right coronary artery
C) Left circumflex artery
D) Posterior descending artery
Correct Answer: A
ST-segment elevation in leads V1-V4 indicates an anterior wall myocardial infarction, which is
most commonly caused by occlusion of the left anterior descending (LAD) artery. The LAD
supplies the anterior wall of the left ventricle and the interventricular septum. The right
coronary artery (B) typically causes inferior wall MI (leads II, III, aVF), the left circumflex
artery (C) causes lateral wall MI (leads I, aVL, V5-V6), and the posterior descending artery (D)
is a branch of the RCA or LCX.
Question 2
A 68-year-old woman with a history of congestive heart failure is prescribed digoxin. She
presents with nausea, vomiting, and yellow vision. Which electrolyte abnormality is most likely
contributing to her symptoms?
A) Hyperkalemia
B) Hypokalemia
C) Hypermagnesemia
D) Hypocalcemia
Correct Answer: B
Digoxin toxicity is potentiated by hypokalemia. Hypokalemia increases the binding of digoxin to
cardiac sodium-potassium ATPase pumps, leading to increased toxicity. Symptoms of digoxin
toxicity include gastrointestinal distress (nausea, vomiting), visual disturbances (yellow vision,
halos), and cardiac arrhythmias. Hyperkalemia (A) is associated with digoxin toxicity but is a
,result, not a predisposing factor. Hypermagnesemia (C) and hypocalcemia (D) are less
commonly associated with digoxin toxicity.
Question 3
A 72-year-old man with a history of smoking presents with progressive shortness of breath and a
chronic cough. Pulmonary function tests show a decreased FEV1/FVC ratio and increased total
lung capacity. Which of the following best describes the underlying pathophysiology?
A) Destruction of alveolar walls and loss of elastic recoil
B) Thickening of the alveolar basement membrane
C) Inflammation and fibrosis of the bronchial walls
D) Excessive mucus production and airway obstruction
Correct Answer: A
The patient's presentation and pulmonary function tests are consistent with emphysema, a type of
COPD characterized by destruction of alveolar walls and loss of elastic recoil. This leads to
airway collapse during expiration, air trapping, and increased total lung capacity. The
decreased FEV1/FVC ratio indicates obstructive lung disease. Option B describes restrictive
lung disease, option C describes chronic bronchitis, and option D is also characteristic of
chronic bronchitis.
Question 4
A 45-year-old man with a history of alcohol abuse presents with jaundice, ascites, and confusion.
Laboratory findings show elevated AST and ALT with an AST/ALT ratio >2. Which of the
following is the most likely diagnosis?
A) Alcoholic hepatitis
B) Viral hepatitis
C) Nonalcoholic fatty liver disease
D) Primary biliary cirrhosis
Correct Answer: A
Alcoholic hepatitis is characterized by jaundice, ascites, and hepatic encephalopathy
, (confusion). The AST/ALT ratio >2 is classic for alcoholic liver disease, as AST is often elevated
more than ALT due to mitochondrial damage and pyridoxal phosphate depletion. Viral hepatitis
(B) typically has ALT > AST, nonalcoholic fatty liver disease (C) usually has a ratio <1, and
primary biliary cirrhosis (D) is an autoimmune disease with elevated alkaline phosphatase and
anti-mitochondrial antibodies.
Question 5
A 28-year-old woman presents with fatigue, weight gain, and cold intolerance. Laboratory
findings show elevated TSH and low free T4. Which of the following is the most likely cause?
A) Hashimoto's thyroiditis
B) Graves' disease
C) Subacute thyroiditis
D) Pituitary adenoma
Correct Answer: A
Hashimoto's thyroiditis is the most common cause of hypothyroidism, characterized by elevated
TSH and low free T4. This autoimmune condition results in destruction of the thyroid gland.
Graves' disease (B) is a cause of hyperthyroidism with low TSH and high T4. Subacute
thyroiditis (C) typically presents with a painful thyroid and transient hyperthyroidism. A
pituitary adenoma (D) secreting TSH would cause elevated TSH and elevated T4.
Question 6
A 60-year-old man with a history of diabetes presents with a non-healing ulcer on his right foot.
The ulcer is painless and located over the first metatarsal head. Which of the following is the
most likely underlying cause?
A) Peripheral neuropathy
B) Peripheral arterial disease
C) Venous insufficiency
D) Pressure ulcer
