Comprehensive Quiz Bank for
the NBME CBSE and USMLE Step
1 (2024/2025 Edition) for actual
test and answers
1. Cardiology - Inferior Wall MI
A 45-year-old man presents with severe chest pain radiating to his left
arm. His ECG shows ST-segment elevation in leads II, III, and aVF. Which
coronary artery is most likely occluded?
• A) Left anterior descending artery
• B) Left circumflex artery
• C) Right coronary artery ✔
• D) Posterior descending artery
Rationale: ST-segment elevations in leads II, III, and aVF indicate an
inferior wall myocardial infarction. The right coronary artery supplies the
inferior wall of the left ventricle and is the vessel most often occluded in
this setting .
2. Endocrinology - Amenorrhea
A 30-year-old woman reports that she has not had a menstrual period
for the past six months. She is not pregnant and has no history of
medical problems. Laboratory studies show low serum estradiol, low or
normal FSH, and low LH. What is the most likely diagnosis?
• A) Primary ovarian insufficiency
• B) Polycystic ovary syndrome
• C) Hypothalamic amenorrhea ✔
• D) Asherman syndrome
Rationale: Hypothalamic amenorrhea is characterized by low
gonadotropins (LH and FSH) and low estradiol, distinguishing it from
primary ovarian insufficiency (high FSH) and PCOS (normal/high LH) .
,3. Pulmonary - Obstructive vs. Restrictive Disease
A 65-year-old man with a 20-pack-year smoking history presents with
progressive shortness of breath and a chronic cough. Pulmonary
function tests reveal a decreased FEV1/FVC ratio and an increased total
lung capacity (TLC) with increased residual volume. Which of the
following is the most likely underlying pathological abnormality?
• A) Destruction of alveolar walls and loss of elastic recoil ✔
• B) Thickening of bronchial walls and mucous gland hyperplasia
• C) Interstitial fibrosis with honeycombing
• D) Granulomatous inflammation of the small airways
Rationale: The PFT pattern—reduced FEV1/FVC ratio with hyperinflation
(increased TLC and residual volume)—is classic for emphysema. The
primary pathology is destruction of alveolar septa and loss of elastic
fibers .
4. Pharmacology - Competitive Antagonists
A patient is treated with a drug that acts as a competitive antagonist.
How does this affect the Vmax and Km of the target enzyme/receptor?
• A) Vmax decreases, Km stays the same
• B) Vmax stays the same, Km increases ✔
• C) Vmax increases, Km decreases
• D) Vmax decreases, Km decreases
Rationale: Competitive inhibitors compete for the active site; Vmax can
still be reached with enough substrate, but the concentration of
substrate needed to reach half Vmax (Km) increases .
5. Biostatistics - Positive Predictive Value
What is the positive predictive value (refer to chart)?
• Answer: .67
Rationale: Positive predictive value is the probability that a patient with
a positive test has a disease, calculated as A/(A+B) .
• 6. 26-year-old woman, ED, 2-day runny nose. Patient has to
wait 6 hours to be seen. In addition to apologizing, what is the
most appropriate remark?
, o Answer: Thank you for waiting. How can I help you today?
o Rationale: Acknowledges the patient's wait and focuses on
the current medical issue.
• 7. 26-year-old man, ER, 30 minutes after being shot in leg.
Pulse 120/min, BP 80/60. Findings compared with healthy
adult?
o Answer: Baroreceptor firing decreased, SVR increased.
o Rationale: Hemorrhagic shock leads to decreased
baroreceptor firing, triggering a sympathetic response that
increases systemic vascular resistance (SVR) to maintain
blood pressure.
• 8. 36-year-old man with fluid in abdomen. In which of the
following areas as indicated by the arrow?
o Answer: Omental Bursa (lesser sac)
o Rationale: The omental bursa is a potential space in the
abdomen where fluid can accumulate.
• 9. Positive predictive value (refer to chart) calculation.
o Answer: .67
o Rationale: PPV = A/(A+B). It is the probability that a patient
with a positive test actually has the disease.
• 10. 75-year-old woman with T2DM and HTN, emigrated from
Argentina. Most appropriate person to serve as interpreter?
o Answer: Telephone interpreter
o Rationale: Telephone interpreter services provide
professional, confidential, and readily available interpretation.
• 11. During a study of renal glomeruli, if efferent arteriole is
constricted, which Starling forces are likely to change in the
glomeruli?
o Answer: Increased Hydrostatic Pressure
o Rationale: Efferent arteriole constriction increases resistance
to outflow, raising hydrostatic pressure within the glomerular
capillaries.
• 12. 2-year-old with neurocognitive dysfunction, irritable, poor
eye contact, hand flapping. Maternal uncle with cognitive
disabilities.
, o Answer: Trinucleotide Repeat Expansion (Fragile X)
o Rationale: Fragile X syndrome is an X-linked dominant
disorder caused by a trinucleotide (CGG) repeat expansion in
the FMR1 gene, leading to intellectual disability and
characteristic features.
• 13. 33-year-old man, post-radical thyroidectomy, serum
calcium 7.5, albumin 4g/dl, PTH 200. Damage to which vessel?
o Answer: Branch of Thyrocervical Trunk
o Rationale: The inferior thyroid arteries, branches of the
thyrocervical trunk, supply the parathyroid glands. Damage
during surgery leads to hypoparathyroidism and
hypocalcemia.
• 14. 46-year-old woman with fatigue, muscle weakness, on
thiazide diuretics for HTN. Hypokalemia, hypotension, brisk
reflexes. Likely cause?
o Answer: Adverse Drug Effect
o Rationale: Thiazide diuretics can cause hypokalemia, which
leads to muscle weakness and hyperreflexia.
• 15. 55-year-old man who is nice to nurses but mean to his
youngest child. Most likely explanation?
o Answer: Splitting
o Rationale: Splitting is a defense mechanism where a person
views others as all good or all bad, common in borderline
personality disorder.
• 16. Study design: feasibility of acupuncture in 60 children with
chronic headache, all treated.
o Answer: Case-Series
o Rationale: A case-series is a descriptive study following a
group of patients with a similar diagnosis or treatment,
without a control group.
• 17. 10-month-old boy with fever, cough, intercostal
retractions, diffuse wheezes, rhonchi. Infectious agent
property?
o Answer: Mediation of Cell Entry via a fusion protein
the NBME CBSE and USMLE Step
1 (2024/2025 Edition) for actual
test and answers
1. Cardiology - Inferior Wall MI
A 45-year-old man presents with severe chest pain radiating to his left
arm. His ECG shows ST-segment elevation in leads II, III, and aVF. Which
coronary artery is most likely occluded?
• A) Left anterior descending artery
• B) Left circumflex artery
• C) Right coronary artery ✔
• D) Posterior descending artery
Rationale: ST-segment elevations in leads II, III, and aVF indicate an
inferior wall myocardial infarction. The right coronary artery supplies the
inferior wall of the left ventricle and is the vessel most often occluded in
this setting .
2. Endocrinology - Amenorrhea
A 30-year-old woman reports that she has not had a menstrual period
for the past six months. She is not pregnant and has no history of
medical problems. Laboratory studies show low serum estradiol, low or
normal FSH, and low LH. What is the most likely diagnosis?
• A) Primary ovarian insufficiency
• B) Polycystic ovary syndrome
• C) Hypothalamic amenorrhea ✔
• D) Asherman syndrome
Rationale: Hypothalamic amenorrhea is characterized by low
gonadotropins (LH and FSH) and low estradiol, distinguishing it from
primary ovarian insufficiency (high FSH) and PCOS (normal/high LH) .
,3. Pulmonary - Obstructive vs. Restrictive Disease
A 65-year-old man with a 20-pack-year smoking history presents with
progressive shortness of breath and a chronic cough. Pulmonary
function tests reveal a decreased FEV1/FVC ratio and an increased total
lung capacity (TLC) with increased residual volume. Which of the
following is the most likely underlying pathological abnormality?
• A) Destruction of alveolar walls and loss of elastic recoil ✔
• B) Thickening of bronchial walls and mucous gland hyperplasia
• C) Interstitial fibrosis with honeycombing
• D) Granulomatous inflammation of the small airways
Rationale: The PFT pattern—reduced FEV1/FVC ratio with hyperinflation
(increased TLC and residual volume)—is classic for emphysema. The
primary pathology is destruction of alveolar septa and loss of elastic
fibers .
4. Pharmacology - Competitive Antagonists
A patient is treated with a drug that acts as a competitive antagonist.
How does this affect the Vmax and Km of the target enzyme/receptor?
• A) Vmax decreases, Km stays the same
• B) Vmax stays the same, Km increases ✔
• C) Vmax increases, Km decreases
• D) Vmax decreases, Km decreases
Rationale: Competitive inhibitors compete for the active site; Vmax can
still be reached with enough substrate, but the concentration of
substrate needed to reach half Vmax (Km) increases .
5. Biostatistics - Positive Predictive Value
What is the positive predictive value (refer to chart)?
• Answer: .67
Rationale: Positive predictive value is the probability that a patient with
a positive test has a disease, calculated as A/(A+B) .
• 6. 26-year-old woman, ED, 2-day runny nose. Patient has to
wait 6 hours to be seen. In addition to apologizing, what is the
most appropriate remark?
, o Answer: Thank you for waiting. How can I help you today?
o Rationale: Acknowledges the patient's wait and focuses on
the current medical issue.
• 7. 26-year-old man, ER, 30 minutes after being shot in leg.
Pulse 120/min, BP 80/60. Findings compared with healthy
adult?
o Answer: Baroreceptor firing decreased, SVR increased.
o Rationale: Hemorrhagic shock leads to decreased
baroreceptor firing, triggering a sympathetic response that
increases systemic vascular resistance (SVR) to maintain
blood pressure.
• 8. 36-year-old man with fluid in abdomen. In which of the
following areas as indicated by the arrow?
o Answer: Omental Bursa (lesser sac)
o Rationale: The omental bursa is a potential space in the
abdomen where fluid can accumulate.
• 9. Positive predictive value (refer to chart) calculation.
o Answer: .67
o Rationale: PPV = A/(A+B). It is the probability that a patient
with a positive test actually has the disease.
• 10. 75-year-old woman with T2DM and HTN, emigrated from
Argentina. Most appropriate person to serve as interpreter?
o Answer: Telephone interpreter
o Rationale: Telephone interpreter services provide
professional, confidential, and readily available interpretation.
• 11. During a study of renal glomeruli, if efferent arteriole is
constricted, which Starling forces are likely to change in the
glomeruli?
o Answer: Increased Hydrostatic Pressure
o Rationale: Efferent arteriole constriction increases resistance
to outflow, raising hydrostatic pressure within the glomerular
capillaries.
• 12. 2-year-old with neurocognitive dysfunction, irritable, poor
eye contact, hand flapping. Maternal uncle with cognitive
disabilities.
, o Answer: Trinucleotide Repeat Expansion (Fragile X)
o Rationale: Fragile X syndrome is an X-linked dominant
disorder caused by a trinucleotide (CGG) repeat expansion in
the FMR1 gene, leading to intellectual disability and
characteristic features.
• 13. 33-year-old man, post-radical thyroidectomy, serum
calcium 7.5, albumin 4g/dl, PTH 200. Damage to which vessel?
o Answer: Branch of Thyrocervical Trunk
o Rationale: The inferior thyroid arteries, branches of the
thyrocervical trunk, supply the parathyroid glands. Damage
during surgery leads to hypoparathyroidism and
hypocalcemia.
• 14. 46-year-old woman with fatigue, muscle weakness, on
thiazide diuretics for HTN. Hypokalemia, hypotension, brisk
reflexes. Likely cause?
o Answer: Adverse Drug Effect
o Rationale: Thiazide diuretics can cause hypokalemia, which
leads to muscle weakness and hyperreflexia.
• 15. 55-year-old man who is nice to nurses but mean to his
youngest child. Most likely explanation?
o Answer: Splitting
o Rationale: Splitting is a defense mechanism where a person
views others as all good or all bad, common in borderline
personality disorder.
• 16. Study design: feasibility of acupuncture in 60 children with
chronic headache, all treated.
o Answer: Case-Series
o Rationale: A case-series is a descriptive study following a
group of patients with a similar diagnosis or treatment,
without a control group.
• 17. 10-month-old boy with fever, cough, intercostal
retractions, diffuse wheezes, rhonchi. Infectious agent
property?
o Answer: Mediation of Cell Entry via a fusion protein
