USMLE STEP 1 SAMPLE TEST QUESTIONS
A 67-year-old woman with congenital bicuspid aortic valve is admitted to the hospital because of a 2-day history of
fever and chills. Current medication is lisinopril. Temperature is 38.0°C (100.4°F), pulse is 90/min, respirations are
20/min, and blood pressure is 110/70 mm Hg. Cardiac examination shows a grade 3/6 systolic murmur that is best
heard over the second right intercostal space. Blood culture grows viridans streptococci susceptible to penicillin. In
addition to penicillin, an antibiotic synergistic to penicillin is administered that may help shorten the duration of this
patient’s drug treatment. Which of the following is the most likely mechanism of action of this additional antibiotic
on bacteria?
(A) Binding to DNA-dependent RNA polymerase
(B) Binding to the 30S ribosomal protein
© Competition with p-aminobenzoic acid
(D) Inhibition of dihydrofolate reductase
(E) Inhibition of DNA gyrase
2. A 12-year-old girl is brought to the physician because of a 2-month history of intermittent yellowing of the eyes and
skin. Physical examination shows no abnormalities except for jaundice. Her serum total bilirubin concentration is
3 mg/dL, with a direct component of 1 mg/dL. Serum studies show a haptoglobin concentration and AST and ALT
activities that are within the reference ranges. There is no evidence of injury or exposure to toxins. Which of the
following additional findings is most likely in this patient?
(A) Decreased activity of UDP glucuronosyltransferase
(B) Gallstones
© Increased hemolysis
(D) Increased serum alkaline phosphatase activity
(E) Ineffective erythropoiesis
3. During an experiment, drug X is added to a muscle bath containing a strip of guinea pig intestinal smooth muscle.
Agonists are added to the bath, and the resultant effects on muscle tension are shown in the table.
Agonist Muscle Tension Before Drug X (g) Muscle Tension After Drug X (g)
Vehicle 6.0 6.1
Acetylcholine 11.3 18.5
Norepinephrine 4.1 4.2
Which of the following types of drugs is most likely to produce effects most similar to those of drug X?
(A) α1-Adrenergic antagonist
(B) β-Adrenergic antagonist
© Cholinesterase inhibitor
(D) Monoamine oxidase inhibitor
(E) Muscarinic antagonist
A 30-year-old woman, gravida 2, para 0, aborta 1, at 28 weeks’ gestation comes to the office for a prenatal visit. She
has had one previous pregnancy resulting in a spontaneous abortion at 12 weeks’ gestation. Today, her vital signs are
within normal limits. Physical examination shows a uterus consistent in size with a 28-week gestation. Fetal
ultrasonography shows a male fetus with no abnormalities. Her blood group is O, Rh-negative. The father’s blood
group is B, Rh-positive. The physician recommends administration of Rho(D) immune globulin to the patient. This
treatment is most likely to prevent which of the following in this mother?
(A) Development of natural killer cells
(B) Development of polycythemia
© Formation of antibodies to RhD
(D) Generation of IgM antibodies from fixing complement in the fetus
(E) Immunosuppression caused by RhD on erythrocytes from the fetus
5. A 55-year-old man is brought to the emergency department because of shortness of breath and confusion for
4 hours. He has hypertension and chronic kidney disease requiring hemodialysis. An ECG shows low voltage with
electrical alternans. Physical examination is most likely to show which of the following findings?
Blood Pressure Jugular Venous Pulsus
(mm Hg) Pulse (/min) Pressure Paradoxus
(A) 85/60 120 increased increased
(B) 85/60 120 increased normal
© 85/60 120 normal normal
(D) 120/80 80 increased increased
(E) 120/80 80 normal increased
(F) 120/80 80 normal normal
6. A 52-year-old woman begins pharmacotherapy after being diagnosed with type 2 diabetes mellitus. Four weeks
later, her hepatic glucose output is decreased, and target tissue glucose uptake and utilization are increased. Which
of the following drugs was most likely prescribed for this patient?
(A) Acarbose
(B) Glyburide
© Metformin
(D) Nateglinide
(E) Repaglinide