NBME 13 Section 4 (Qst 1-50)

50 Questions | Total Attempts: 2576

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NBME 13 Section 4 (Qst 1-50)

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Questions and Answers
  • 1. 
    An 18-year-old man has had temperatures to 38.3°C (101°F), a sore throat, and cervical lymph node enlargement for 8 days. A latex agglutination test result for Epstein-Barr virus antibody is positive. Atypical cells with abundant lacey cytoplasm in the peripheral blood smear are most likely derived from which of the following types of cells?
    • A. 

      B lymphocytes

    • B. 

      Basophils

    • C. 

      Neutrophils

    • D. 

      Plasma cells

    • E. 

      T lymphocytes

  • 2. 
    A 6-year-old boy is brought to the physician by his mother because of a 2-day history of fever, sore throat and occasional vomiting. His temperature is 39'C (102.2°F). Physical examination shows erythema and purulent exudate over the posterior pharyngeal wall and tonsils. The anterior cervical glands are enlarged and tender. A throat culture grows group A Streptococcus. Because he is allergic to penicillin, treatment with erythromycin is begun. His condition improves during the next 2 days. The effectiveness of this antibiotic is most likely due to which of the following actions in protein synthesis?
    • A. 

      Causes misreading of mRNA information

    • B. 

      Functions as an analog of aminoacyl-tRNA

    • C. 

      Inactivates elongation factor-2

    • D. 

      Interferes in aminoacyl-tRNA binding

    • E. 

      Interferes with translocation

  • 3. 
    A male newborn at 34 weeks’ gestation is delivered vaginally. Physical examination shows no abnormalities except for a 1-cm, raised, red area on the anterior section of the neck. His mother is concerned, and the physician explains that the lesion is a hemangioma, a benign growth. This neoplasm most likely originated in which of the following tissues?
    • A. 

      Ectoderm

    • B. 

      Endothelium

    • C. 

      Neural crest cells

    • D. 

      Notochord

    • E. 

      Yolk sac

  • 4. 
    A 21-year-old woman who is a medical student comes to the physician for evaluation of recurrent throbbing headache associated with sensitivity to light and sound. Neurologic examination shows no abnormalities. Sumatriptan is initiated for suspected migraine. This drug is most appropriate for this patient because of its ability to activate which of the following types of receptors?
    • A. 

      Acetylcholine

    • B. 

      ү-Aminobutyric acid

    • C. 

      Dopamine

    • D. 

      Neurotensin

    • E. 

      Serotonin

  • 5. 
    A screening test is used to detect prostate cancer in a population of 100,000 men. The test has a sensitivity of 70% and a specificity of 90%. The test is then used to screen a second population in which the prevalence of prostate cancer is different. Which of the following is the most likely effect on the positive predictive value of this test?
    • A. 

      Decreases as prevalence increases

    • B. 

      Increases as prevalence decreases

    • C. 

      Increases as prevalence increases

    • D. 

      No change as prevalence changes

  • 6. 
    A 60-year-old man comes to the physician because of progressive weakness of his hands during the past 6 months. He works as a carpenter and has had difficulty handling his tools. He has smoked 1 pack of cigarettes daily for 45 years. He drinks two beers daily during the workweek and approximately six beers daily on weekends. Physical examination shows no lymphadenopathy. There is decreased strength (4/5) in the upper and lower extremities and atrophy of the muscles of the hands. He has diffuse hyperreflexia. Fasciculations are noticed on the muscles of the hands and upper extremities. Sensory examination is normal. Over the course of this disease, which of the following findings is most likely?
    • A. 

      Dementia

    • B. 

      Difficulty swallowing

    • C. 

      Loss of facial sensation

    • D. 

      Loss of peripheral vibratory sensation

    • E. 

      Nystagmus

  • 7. 
    A 55-year-old man comes to the physician because of a 3-day history of fever and shaking chills. He has end-stage renal disease treated with hemodialysis. His temperature is 39.2°C (102.6˚F), pulse is 110/min, and blood pressure is 156/92 mm Hg. Physical examination shows a tunneled central venous catheter entering the right side of the chest below the clavicle; the area surrounding the catheter is not tender. Echocardiography shows a 3-cm vegetation on the tricuspid valve. Which of the following is the most likely causal organism?
    • A. 

      Escherichia coli

    • B. 

      KIebsiella pneumoniae

    • C. 

      Staphylococcus aureus

    • D. 

      Streptococcus pyogenes (group A)

    • E. 

      Viridans streptococcus

  • 8. 
    A 3-year-old girl is found to have a grade 4/6, loud, harsh, high-pitched holosystolic murmur that radiates over the precordium and a palpable thrill at the left sternal border. Which of the following defects is most likely in this patient?
    • A. 

      Aortic regurgitation

    • B. 

      Aortic stenosis

    • C. 

      Atrial septal defect

    • D. 

      Coarctation of the aorta

    • E. 

      Mitral regurgitation

    • F. 

      Mitral stenosis

    • G. 

      Patent ductus arteriosus

    • H. 

      Pulmonic stenosis

    • I. 

      Tricuspid regurgitation

    • J. 

      Ventricular septal defect

  • 9. 
    A 48-year-old woman comes to the emergency department because of a 3-hour history of nausea and acute, sharp, right-sided lower abdominal pain that radiates to her back. She says the pain started 30 minutes into her aerobics class and has increased in severity since then. Physical examination shows an enlarged right ovary. The result of a urine pregnancy test is negative. Ultrasonography of the pelvis confirms the presence of an enlarged ovary, and Doppler ultrasonography shows decreased adnexal flow. Which of the following structures is most likely affected in this patient?
    • A. 

      Mesometrium

    • B. 

      Oviduct

    • C. 

      Round ligament of the uterus

    • D. 

      Suspensory ligament

    • E. 

      Transverse cervical ligament

  • 10. 
    A 20-year-old man comes to the physician because of cramping abdominal pain and diarrhea during the past 3 weeks; he has had a 4.5-kg (10-lb) weight loss during this period. The pain is exacerbated following meals. He went on a camping trip in upstate New York 3 weeks ago, swimming in the nearby lakes and hiking in the mountains. His vital signs are normal. Physical examination shows no abnormalities. Which of the following diagnostic tests is most likely to identify the causal organism of this patient's condition?
    • A. 

      Culture of the stool for enteric bacterial pathogens

    • B. 

      Electron microscopy of the stool for small round viruses

    • C. 

      Microscopic examination of the stool for ova and parasites

    • D. 

      Polymerase chain reaction test of the stool for Shiga toxin

    • E. 

      Proctoscopy and rectal biopsy

  • 11. 
    11. A 43-year-old woman with metastatic colon cancer has maintained remission by taking bevacizumab as a single agent. The ability to administer this agent despite it being a foreign protein is most likely a result of which of the following?
    • A. 

      The agent being a humanized antibody

    • B. 

      The agent containing the variable region of a murine antibody molecule directed against vascular endothelial growth factor

    • C. 

      B-cell dysfunction

    • D. 

      The immunosuppressive effect of previously administered chemotherapy

    • E. 

      T-cell dysfunction

  • 12. 
    A previously healthy 35-year-old man comes to the physician because of a 2-year history of gradually decreasing libido and intermittent inability to achieve erection or orgasm; he also has had decreased growth of facial hair during this period. Puberty began at the age of 12 years. He takes no medications. He does not smoke or drink alcohol. He is 180 cm (5 ft 11 in) tall and weighs 75 kg (165 lb); BMI is 23 kg/m². His vital signs are within normal limits. Physical examination shows a typical male-pattern distribution of hair. Genital examination shows no abnormalities. Serum studies shows thyroid-stimulating hormone concentration of 2 µU/mL, prolactin concentration of 120 ng/mL, and total testosterone concentration of 25 mmol/L (N=10— 35). Semen analysis shows a markedly decreased sperm count with impaired motility. An MRI of the brain shows a 1-cm lesion in the pituitary gland. Administration of which of the following is the most appropriate treatment for this patient?
    • A. 

      Bromocriptine

    • B. 

      Gonadotropin-releasing hormone

    • C. 

      Human chorionic gonadotropin

    • D. 

      Sildenafil

    • E. 

      Testosterone

    • F. 

      Thyroxine

  • 13. 
    A 42-year-old man has an autoimmune disorder resulting in proximal muscle weakness of the lower extremities. Arrows in the photomicrograph shown indicate membranes that contain high concentrations of channels that are targeted by this condition. Which of the following is the most likely diagnosis?
    • A. 

      Multiple sclerosis

    • B. 

      MyasItenia gravis

    • C. 

      Myasthenic (Lambert-Eaton) syndrome

    • D. 

      Periodic paralysis

    • E. 

      Tetany

  • 14. 
    An investigator is studying the human immune response to tumor cell antigens in malignancies. Which of the following sets of cancer types and tumor antigens is most likely to produce the highest antibody titer? Cancer Type                                                                       Tumor Antigen A)       B-cell lymphoma                                                                             CD19 B)         Breast cancer                                                                              HER2/neu C)        Cervical cancer                                                      human papillomavirus type 16 E6 protein D)           Melanoma                                                                                 tyrosinase E)        Prostate cancer                                                            prostatic acid phosphatase
    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

  • 15. 
    A 45-year-old woman has a 2-week history of a heart murmur and hepatomegaly. She has a 3-month history of flushing with hypotension and crampy diarrhea. Which of the following is the most likely site of a primary neoplasm in this patient?
    • A. 

      Adrenal gland

    • B. 

      Bone marrow

    • C. 

      Kidney

    • D. 

      Ovary

    • E. 

      Small intestine

  • 16. 
    A 22-year-old woman comes to the physician 3 months after she noticed a painless, slowly enlarging mass on the left side of her neck. Physical examination shows a freely mobile, soft, cystic mass with a cutaneous surface opening. The physician explains that it is from incomplete fusion during embryonic development. Which of the following is the most likely location of the opening of the duct leading to the mass in this patient?
    • A. 

      Anterior to the sternocleidomastoid muscle

    • B. 

      Midline on the neck

    • C. 

      Postauricular

    • D. 

      Posterior to the parotid gland

    • E. 

      Submental

  • 17. 
    A 42-year-old man comes to the physician because of a 4-week history of muscle cramping and pain. Two months ago, he began treatment with simvastatin (80 mg daily) for hypercholesterolemia.  After 1 month, marked improvement was noted in his serum LDL-cholesterol concentration, but serum triglyceride concentration remained increased. At that time, gemfibrozil was added to his regimen to decrease his triglyceride concentration. Physical examination today shows no abnormalities. This patient’s myalgia is most likely related to which of the following effects of gemfibrozil on simvastatin?
    • A. 

      Decreased bioavailability

    • B. 

      Increased absorption

    • C. 

      Inhibition of cytochrome P450 metabolism

    • D. 

      Inhibition of hepatic glycosylation

    • E. 

      Inhibition of hepatic sulfation

  • 18. 
    A 30-year-old woman and her 25-year-old husband come to the physician for advice about their risk for having another child with Tay-Sachs disease. Their 6-month-old son was recently diagnosed with this disease. There is a history of this disease in both the woman's and the man's families. Which of the following best represents the risk for this couple’s next child to have Tay-Sachs disease?
    • A. 

    • B. 

      10%

    • C. 

      25%

    • D. 

      50%

    • E. 

      100%

  • 19. 
    An 18-month-old boy is brought to the physician because of progressive facial abnormalities and slow growth during the past 6 months. He has an older brother with similar abnormalities who also has mental retardation. The patient is below the 3rd percentile for length and at the 10Ih percentile for weight. Physical examination shows coarse facial features, hepatosplenomegaly, and joint stiffness. His urine concentrations of dermatan sulfate and heparan sulfate are increased. A deficiency of which of the following enzyme activities is the most likely cause of the findings in this patient?
    • A. 

      Galactosidase

    • B. 

      Glycosylase

    • C. 

      Hexosaminidase A

    • D. 

      Lduronate sulfatase

    • E. 

      Lipoxygenase

  • 20. 
    A 3-year-old girl is brought to the emergency department by her mother 1 hour alter she was found with a half-empty bottle other grandmother's diabetes medication. The mother tells the physician that the child consumed approximately 25 metformin tablets. Physical examination shows no abnormalities. This patient is at greatest risk for which of the following serum abnormalities?
    • A. 

      Decreased calcium concentration

    • B. 

      Decreased glucose concentration

    • C. 

      Decreased sodium concentration

    • D. 

      Increased AST and ALT activities

    • E. 

      Increased creatinine concentration

    • F. 

      Increased lactic acid concentration

  • 21. 
    A 5-year-old boy is brought to the physician by his mother because of a 3-month history of headache, clumsiness, and fatigue. He had a generalized tonic-clonic seizure 1 month ago. His mother says that he often falls while running. Ophthalmologic examination shows ptosis of the left eye and bilateral external ophthalmoplegia. Physical examination shows weakness of the left lower extremity. Serum studies show an increased lactate concentration. Analysis of a calf muscle biopsy specimen obtained from the left lower extremity shows ragged red fibers.  Which of the following metabolic processes is most likely impaired in this patient?
    • A. 

      Fatty acid oxidation

    • B. 

      Gluconeogenesis

    • C. 

      Glycolysis

    • D. 

      Oxidative phosphorylation

    • E. 

      Pentose phosphate pathway

  • 22. 
    A 25-year-old woman comes to the physician because of a 2-day history of decreasing urine output despite ample fluid intake. She underwent operative removal of a perforated appendix 3 weeks ago. She received intravenous gentamicin for 2 weeks. Physical examination shows no abnormalities. Laboratory studies show: Histologic examination of this patient's kidneys would most likely show necrotic cells in which of the following components of the nephron?
    • A. 

      Bowman capsule

    • B. 

      Collecting tubule

    • C. 

      Glomerular basement membrane

    • D. 

      Mesangium

    • E. 

      Proximal tubule

  • 23. 
    A 43-year-old man comes to the physician for a routine health maintenance examination. He is 170 cm (5 ft 7 in) tall and weighs 86 kg (188 lb); BMI is 30 kg/m². Physical examination and laboratory studies show no other abnormalities. He tells the physician, "My older brother just got diagnosed with diabetes. I don't want that to happen to me. What should I do?” Which of the following diets is most likely to be effective in decreasing this patients risk for type 2 diabetes mellitus?
    • A. 

      Low-calorie

    • B. 

      Low-carbohydrate

    • C. 

      Low-cholesterol

    • D. 

      Low-protein

    • E. 

      Low-sodium

  • 24. 
    A 4-year-old boy is brought to the emergency department because of a 1-hour history of headache, nausea and vomiting, and dizziness. Physical examination shows severe lethargy. His venous blood is bright red; carboxyhemoglobin saturation is 30% (reference range < 5%). Which of the following steps in the electron transport pathway is primarily affected in this patient?
    • A. 

      A

    • B. 

      B

    • C. 

      C

    • D. 

      D

    • E. 

      E

  • 25. 
    A 20-year-old man has cramping periumbilical pain. After several hours, the pain shifts to the right lower quadrant and becomes constant. His temperature is 40°C (104°F), and his leukocyte count is 20.000/mm³ with 90% neutrophils. Which of the following mediators is most likely causing this patients fever and leukocytosis?
    • A. 

      Interleukin-1 (IL-1)

    • B. 

      Interleukin-2 (IL-2)

    • C. 

      Leukotriene B₄

    • D. 

      Leukotriene C₄

    • E. 

      Prostaglandin D₂

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