USMLE Step-1 Questionnaire

1. Physiology

A decrease in blood pH will cause which of the following changes in the oxyhemoglobin dissociation curve?
A. Shift to the left
B. Shift to the right
C. No change
D. Increased hemoglobin affinity for oxygen
E. Increased oxygen saturation

2. Anatomy

Damage to the surgical neck of the humerus most likely injures which nerve?
A. Radial
B. Axillary
C. Musculocutaneous
D. Median
E. Ulnar

3. Biochemistry

Which enzyme is deficient in classic galactosemia?
A. Galactokinase
B. Galactose-1-phosphate uridyltransferase
C. Lactase
D. Hexokinase
E. Aldolase B

4. Pathology

A patient with long-standing hypertension develops concentric left ventricular hypertrophy. What is the primary cellular adaptation?
A. Hyperplasia
B. Metaplasia
C. Hypertrophy
D. Dysplasia
E. Atrophy

5. Pharmacology

Which drug is a competitive antagonist at β1-adrenergic receptors?
A. Propranolol
B. Metoprolol
C. Phenoxybenzamine
D. Epinephrine
E. Dobutamine

6. Microbiology

Which organism is most commonly associated with pseudomembranous colitis?
A. Salmonella
B. Shigella
C. Clostridioides difficile
D. Campylobacter jejuni
E. Vibrio cholerae

7. Immunology

Which immunoglobulin is most abundant in serum?
A. IgA
B. IgE
C. IgG
D. IgM
E. IgD

8. Genetics

A disease inherited in an autosomal recessive manner is most likely due to:
A. Structural protein defect
B. Gain-of-function mutation
C. Enzyme deficiency
D. Trinucleotide repeat expansion
E. Mitochondrial mutation

9. Physiology

Which hormone increases calcium reabsorption in the distal tubule?
A. Aldosterone
B. Parathyroid hormone
C. Calcitonin
D. Vitamin D
E. Cortisol

10. Anatomy

The ligamentum arteriosum is a remnant of which fetal structure?
A. Ductus venosus
B. Umbilical vein
C. Ductus arteriosus
D. Foramen ovale
E. Umbilical artery

11. Biochemistry

Which vitamin deficiency causes impaired γ-carboxylation of clotting factors?
A. Vitamin A
B. Vitamin B12
C. Vitamin C
D. Vitamin K
E. Vitamin D

12. Pathology

Atherosclerotic plaques are primarily composed of:
A. Platelets
B. Fibrin
C. Lipid-laden macrophages
D. Neutrophils
E. Plasma cells

13. Pharmacology

Which antibiotic inhibits bacterial DNA gyrase?
A. Penicillin
B. Vancomycin
C. Ciprofloxacin
D. Doxycycline
E. Azithromycin

14. Microbiology

Which organism produces exotoxin that inhibits protein synthesis by inactivating EF-2?
A. E. coli
B. Corynebacterium diphtheriae
C. Clostridium tetani
D. Staphylococcus aureus
E. Neisseria meningitidis

15. Immunology

Which cell type presents antigen via MHC class II molecules?
A. Neutrophils
B. CD8+ T cells
C. Erythrocytes
D. Macrophages
E. NK cells

16. Genetics

Which chromosomal abnormality causes Turner syndrome?
A. Trisomy 21
B. Trisomy 18
C. Monosomy X
D. XXY
E. Triploidy

17. Physiology

Which part of the nephron is impermeable to water?
A. Proximal tubule
B. Descending loop of Henle
C. Ascending loop of Henle
D. Collecting duct
E. Distal tubule (early)

18. Anatomy

The femoral nerve arises from which spinal roots?
A. L1–L2
B. L2–L4
C. L4–S1
D. S1–S3
E. T12–L1

19. Biochemistry

Phenylketonuria results from deficiency of:
A. Tyrosinase
B. Phenylalanine hydroxylase
C. Dihydropteridine reductase
D. Tryptophan hydroxylase
E. Homogentisate oxidase

20. Pathology

Which finding is characteristic of caseous necrosis?
A. Chalky white deposits
B. Preserved tissue architecture
C. Amorphous granular debris
D. Liquefied tissue
E. Fibrous scarring

21. Pharmacology

Which drug causes hyperkalemia as a side effect?
A. Furosemide
B. Hydrochlorothiazide
C. Spironolactone
D. Acetazolamide
E. Mannitol

22. Microbiology

Which virus is a double-stranded DNA virus?
A. Influenza
B. HIV
C. Adenovirus
D. Hepatitis C
E. Rabies

23. Immunology

Type I hypersensitivity reactions are mediated by:
A. IgG
B. IgM
C. IgE
D. IgA
E. Complement

24. Genetics

Which disorder is associated with trinucleotide repeat expansion?
A. Cystic fibrosis
B. Duchenne muscular dystrophy
C. Huntington disease
D. Sickle cell anemia
E. Tay-Sachs disease

25. Physiology

Which lung volume cannot be measured by spirometry?
A. Tidal volume
B. Inspiratory reserve volume
C. Expiratory reserve volume
D. Vital capacity
E. Residual volume

26. Anatomy

The recurrent laryngeal nerve is a branch of which nerve?
A. Glossopharyngeal
B. Hypoglossal
C. Vagus
D. Accessory
E. Phrenic

27. Biochemistry

Which molecule is the rate-limiting substrate for nitric oxide synthesis?
A. Arginine
B. Citrulline
C. Glycine
D. Aspartate
E. Glutamine

28. Pathology

Which cancer is associated with asbestos exposure?
A. Small cell lung carcinoma
B. Mesothelioma
C. Adenocarcinoma of lung
D. Squamous cell carcinoma
E. Large cell carcinoma

29. Pharmacology

Which drug is used to reverse opioid overdose?
A. Naloxone
B. Methadone
C. Buprenorphine
D. Naltrexone
E. Codeine

30. Microbiology

Which parasite causes malaria?
A. Leishmania
B. Trypanosoma
C. Plasmodium
D. Entamoeba
E. Giardia

31. Immunology

Which complement component is responsible for membrane attack complex formation?
A. C3a
B. C3b
C. C5a
D. C5b–C9
E. C1q

32. Genetics

Which condition shows anticipation?
A. Down syndrome
B. Turner syndrome
C. Myotonic dystrophy
D. Cystic fibrosis
E. Hemophilia A

33. Physiology

Insulin increases uptake of glucose into which tissues?
A. Brain
B. Liver
C. Skeletal muscle
D. Red blood cells
E. Renal tubules

34. Anatomy

The appendix is supplied by which artery?
A. Right colic
B. Ileocolic
C. Middle colic
D. Inferior mesenteric
E. Superior rectal

35. Biochemistry

Which amino acid is a precursor of serotonin?
A. Tyrosine
B. Tryptophan
C. Phenylalanine
D. Histidine
E. Glutamate

36. Pathology

Reed-Sternberg cells are characteristic of:
A. Non-Hodgkin lymphoma
B. Hodgkin lymphoma
C. Multiple myeloma
D. Leukemia
E. Burkitt lymphoma

37. Pharmacology

Which anesthetic causes malignant hyperthermia?
A. Lidocaine
B. Propofol
C. Halothane
D. Ketamine
E. Nitrous oxide

38. Microbiology

Which organism is catalase-positive and coagulase-positive?
A. Staphylococcus epidermidis
B. Streptococcus pyogenes
C. Enterococcus faecalis
D. Staphylococcus aureus
E. Neisseria gonorrhoeae

39. Immunology

Which cytokine promotes Th1 differentiation?
A. IL-4
B. IL-5
C. IL-10
D. IL-12
E. TGF-β

40. Genetics

Which enzyme is defective in Xeroderma pigmentosum?
A. DNA polymerase
B. DNA ligase
C. Nucleotide excision repair enzymes
D. RNA polymerase
E. Telomerase

41. Physiology

Which acid-base disorder is caused by prolonged vomiting?
A. Metabolic acidosis
B. Respiratory acidosis
C. Metabolic alkalosis
D. Respiratory alkalosis
E. Mixed disorder

42. Anatomy

Which muscle abducts the arm from 15° to 90°?
A. Supraspinatus
B. Deltoid
C. Trapezius
D. Latissimus dorsi
E. Teres major

43. Biochemistry

Which pathway produces NADPH?
A. Glycolysis
B. TCA cycle
C. Pentose phosphate pathway
D. β-oxidation
E. Urea cycle

44. Pathology

Which tumor marker is elevated in hepatocellular carcinoma?
A. CEA
B. PSA
C. AFP
D. CA-125
E. CA 19-9

45. Pharmacology

Which drug is a calcium channel blocker?
A. Atenolol
B. Enalapril
C. Verapamil
D. Losartan
E. Digoxin

46. Microbiology

Which organism causes urethritis with no cell wall?
A. Chlamydia
B. Neisseria
C. Mycoplasma
D. Ureaplasma
E. Treponema

47. Immunology

Which cell mediates antibody-dependent cellular cytotoxicity (ADCC)?
A. B cell
B. CD4+ T cell
C. CD8+ T cell
D. NK cell
E. Neutrophil

48. Genetics

Which inheritance pattern is seen in mitochondrial diseases?
A. Autosomal recessive
B. Autosomal dominant
C. X-linked
D. Maternal inheritance
E. Codominant

49. Physiology

Which hormone is secreted by the zona glomerulosa?
A. Cortisol
B. Aldosterone
C. Androgens
D. Progesterone
E. Estrogen

50. Anatomy

The cauda equina ends at which vertebral level in adults?
A. L1–L2
B. L3–L4
C. L4–L5
D. S1–S2
E. Coccyx

Answer Key

The nurse is caring for a client at 39 weeks gestation who is receiving an IV oxytocin infusion for induction of labor. The nurse notes recurrent late decelerations on the fetal monitor. Which of the following actions should the nurse take? Select all that apply.

	1.Administer an IV fluid bolus.
	2.Reposition the client laterally.
	3.Discontinue the IV oxytocin infusion.
	4.Prepare the client for an amnioinfusion.
	5.Apply abdominal vibroacoustic stimulation.