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Exam Section 2: Item 1 o f 50 I M ark
N a tio n a l B oard o f M e d ica l E xam iners C o m p re h e n sive Basic S cience Self-Assessm ent
T im e R e m a in in g : 4 h r 19 m in 55 sec
1. 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?
O A) Acetylcholine
B) Y-Aminobutyric acid O C) Dopamine
O D) Neurotensin 0 E) Serotonin
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2. A 5-year-old girl is brought to the physician because of listlessness, fatigue, and dull pain in the right upper quadrant of the abdomen. Her height and weight are below the 25th percentile.
Laboratory findings indicate that the content of her (3-globin chain is 15% to 20% of normal. Sequencing of the (3-globin gene shows a point mutation in a sequence 3' to the coding region in which AATAAA is converted to AACAAA. Consequently, the amount of mRNAfor (3-globin is decreased to 10% of normal. Which of the following functions in mRNA synthesis and
processing is most likely encoded by the sequence AATAAA?
© A) Capping with GTP
B) Cleavage and polyadenylation
© C) Silencing of the promoter
D) Splicing of the initial mRNA transcript in the nucleus
© E) Transport of the mRNA out of the nucleus
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3. An investigator breeds a transgenic strain of mice that develops severe fasting hypoglycemia. Administration of glucagon does not correct the hypoglycemia, but administration of epinephrine results in an increase in the serum glucose concentration. Which of the following proteins is most likely defective in this mouse strain?
O A) Adenylyl cyclase O B) Glucagon receptor
C) Glycogen phosphorylase O D) Heterotrimeric G protein
E) Phosphorylase kinase
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4. 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?
O A) Dementia
o B) Difficulty swallowing O C) Loss of facial sensation
D) Loss of peripheral vibratory sensation O E) Nystagmus
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5. A 60-year-old man has had episodes of fluctuating weakness for the past 2 years. The weakness was first noticed when he had difficulty lifting books. At times, he has had drooping of the eyelids and double vision. Recently, he has had difficulty climbing stairs and regurgitation of liquids into his nose. On physical examination, the weakness increases with repeated exercise.
An x-ray of the chest shows a mass in the mediastinum. Which of the following laboratory assays is most likely to be positive?
O A) Acetylcholine receptor antibody
N a tion a: Board o f M ed ica l Examiners - G o o g le C h rom e [ o | 0 Q h ttp s ://w w w .s ta rtte s t.e o m /a p i/5 .l. 1.0/TTDStart.aspx?SVC=f3fd94ad-4a91-4962-b764-2d4caccal061
Exam Section 2: Item 6 o f 50 N a tio n a l B oard o f M e d ica l E xa m in e rs T im e R e m a in in g :
■ M ark C o m p re h e n sive Basic S cience Self-Assessm ent 4 h r 16 m in 33 sec
6. A 3-year-old girl is brought to the emergency department by her mother 1 hour after she was found with a half-empty bottle of her 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 O D) Increased AST and ALT activities
E) Increased creatinine concentration F) Increased lactic acid concentration
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7. A 65-year-old woman with diabetic ketoacidosis has had a fever and proptosis of the left eye over the past 3 days. She is unable to move the left eye. A black eschar is present on the nasal mucosa. Which of the following is the most likely diagnosis?
A) Aspergillosis
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8. 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
O C) Inhibition of cytochrome P450 metabolism D) Inhibition of hepatic glycosylation
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Exam Section 2: Item 9 o f 50 National Board o f Medical Examiners Tim e Remaining:
| Comprehensive Basic Science Self-Assessment 4 hr 12 min 32 sec
9. 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:
Serum
Histologic examination of this patient's kidneys would most likely show necrotic cells in which of the following components of the nephron?
C A) Bowman capsule
r -■' N ational Board o f Medical Examiners - Google Chrome 103 cm (41 in). His blood pressure is 140/90 mm Hg. Physical examination shows a protuberant abdomen. Laboratory studies show fasting serum glucose and insulin concentrations that are increased and remain increased 2 hours after the patient receives 75 g of oral glucose. Which of the following sets of additional laboratory findings in serum is most likely in this patient?
Triglycerides HDL-cholesterol Free Fatty Acids
© A) *
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Exam Section 2: Item 11 o f 50 National Board o f Medical Examiners
| l^ ark Comprehensive Basic Science Self-Assessment
Tim e Remaining:
4 hr 7 min 35 sec
11. A 47-year-old man is brought to the emergency department 3 hours after the sudden onset of sharp left flank pain and fever. He has had similar episodes during the past 5 years. His temperature is 38.3°C (100.9°F). Abdominal examination shows exquisite tenderness in the left costovertebral region. Laboratory studies show:
Hemoglobin 16 g/dL
Imaging studies show hydronephrosis of the left kidney and a staghorn calculus. A nephrectomy is done; the calculus is composed of magnesium ammonium phosphate (struvite). Culture of a urine sample is most likely to grow which of the following organisms?