Exam Section 1: Item 1 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 59 m in 0 sec
1. A 55-year-old man with hypertension has the sudden onset of weakness of the right lower extremity. The right upper extremity is not affected. The most likely cause is occlusion of which of the following arteries?
Exam Section 1: Item 2 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 59 min 44 sec
2. A 75-year-old woman is brought to the emergency department semicomatose 24 hours after hitting the back of her head in a fall. No symptoms were present after the fall, but she developed blurred vision and weakness of the left extremities 18 hours after the fall. Examination shows left hemiparesis; the right pupil is dilated and unresponsive to light. A CT scan without contrast shows a diffuse extra-axial hemorrhage over the right cerebral hemisphere. Which of the following is the most likely mechanism of injury?
National Board of Medical Examiners Comprehensive Basic Science Self-Assessment
Tim e Rem aining:3 hr 57 min 46 sec
3. A 27-year-o ld m an is eva luated fo r ve rtigo and hearing loss in the right ear. W hich o f the fo llow ing labe led crania l nerves is m ost likely dam aged?
Exam Section 1: Item 4 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 57 m in 27 sec
4. A 65-year-old man comes to the physician because of shortness of breath on exertion for 3 years. He has smoked 2 packs of cigarettes daily for 50 years. His arterial oxygen saturation is 84% (N = 95-98%). This patient's inability to maintain adequate tissue oxygenation will most likely lead to increased production of which of the following in his erythrocytes?
Exam Section 1: Item 5 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 57 min 13 sec
5. An intoxicated 24-year-old woman is brought to the emergency department because of a femoral fracture sustained in a fall from a second floor balcony. Two days after internal fixation of the fracture, she is agitated, appears confused, demands to leave the hospital against medical advice, and accuses the staff of torturing her. Pulse is 120/min, and blood pressure is 160/110 mm Hg. Which of the following best explains this behavior?
Exam Section 1: Item 6 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 56 min 41 sec
6. In a study of 100 subjects with colonic polyposis, 20 develop colonic malignancies over a 10-year follow-up period. To estimate the relative risk of colonic polyposis for the development of colon cancer, which of the following control groups would be best?
Exam Section 1: Item 7 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 56 min 22 sec
7- Which of the following neurotransmitters is released in excess following ischemia and can initiate a receptor-mediated Ca2+ influx that leads to neuronal death?
Exam Section 1: Item 8 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 55 min 53 sec
8. A 47-year-old man comes to the emergency department because he felt the sudden loss of sensation and ability to move the left side of his body. His father died of a stroke at this same age. Physical examination shows no neurologic defects. The patient seems unconcerned about his symptoms. Which of the following is the most likely diagnosis?
Exam Section 1: Item 9 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 55 m in 41 sec
9. Which of the following conditions is most likely to be present when transverse histologic sections of the cervical spinal cord at C-6 show degeneration of both corticospinal tracts and atrophy of the ventral roots?
Exam Section 1: Item 10 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 55 m in 31 sec
10. A 26-year-old man comes to the physician because of a 6-month history of losing consciousness when he laughs. He sleeps 12 to 14 hours every night, has vivid dreams and nightmares, and feels tired during the day. He was recently involved in a motor vehicle collision. Findings on physical examination are unremarkable. Which of the following is the most likely diagnosis?
Exam Section 1: Item 11 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 55 min 18 sec
11. A 58-year-old woman dies after a 2-year history of progressive memory loss, disorientation to time and place, and increasingly frequent episodes of lethargy and confusion. There were no focal neurologic deficits. Which of the following findings is most likely at autopsy?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 55 min 9 sec
12. A 16-year-old boy has pain in the right knee immediately after twisting it while playing soccer. Examination shows excessive posterior sliding of the tibia when it is pushed backward with the knee flexed. Which of the following ligaments is most likely injured?
Exam Section 1: Item 13 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 54 m in 59 sec
13. Two days after a hike in the woods, a 26-year-old man has a raised, red, vesicular rash on his right lower extremity. Which of the following cell types is responsible for sensitivity to the relevant antigen?
O 9 r,*,* oPrevious Next a* 1 Lab Values Review Help Pause
Exam Section 1: Item 14 of 50■ Mark
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 54 min 45 sec
14. When a movement is planned but not executed, which of the following labeled regions of the normal brain shown will show an increase in activity in a functional MRI?
Exam Section 1: Item 15 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 54 min 34 sec
15. A 25-year-old woman who has been taking an unknown drug for 3 weeks is having a very heavy menstrual period. Petechiae are present on her legs. She is anemic. Platelet count is 3000/mm3. Which of the following findings indicates that her thrombocytopenia is a result of toxic suppression of platelet production by the drug instead of an autoimmune disorder?
I Board of M edical Exam inersive Basic Science Self-Assessment
T im e Rem aining:3 hr 54 min 5 sec
Exam Section 1: Item 17 of 50■ Mark
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 53 min 55 sec
17. Five separate analyses for serum glucose are done using a new method on a single sample. The values obtained are 102,100, 96,101, and 98 mg/dL. These types of data are used to determine which of the following characteristics of the test?
Exam Section 1: Item 18 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 53 min 41 sec
18. In organ transplantation, graft-versus-host disease may be induced by donor T lymphocytes. Which of the following disease-specific organ transplants is most likely to derive some benefit from this graft-versus-host response?
Exam Section 1: Item 19 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 53 m in 30 sec
19. A 27-year-old woman comes to the clinic because of a 7-year history of intermittent headaches, abdominal pain and bloating, low back pain, diarrhea, pain during sexual intercourse, decreased interest in sex, and difficulty with balance. She tells the physician that she is frustrated because she cannot work because of her symptoms. She has seen 12 physicians in the past 5 years, none of whom has been able to diagnose her condition. This patient most likely has which of the following disorders?
Exam Section 1: Item 20 of 50 National Board of Medical Examiners Time Remaining:g Mark Comprehensive Basic Science Self-Assessment 3 hr 52 min 31 sec
20. A 49-year-old man comes to the physician because of increasingly severe pain in his right thumb during the past 2 days. He has a 10-year history of type 2 diabetes mellitus. Physical examination shows swelling and erythema of the thumb. X-rays of the right thumb show osteomyelitis at the arrows shown. Which of the following structures is most likely affected by the pathologic process?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 52 min 0 sec
21. A 32-year-old man who is seropositive for HIV has a decreased CD4+ T-lymphocyte count. Which of the following is most likely decreased in this patient?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 51 min 14 sec
23. A study is done to determine the relationship between use of oral contraceptives and cervical cancer. Study subjects include 50,000 women who are using oralcontraceptives and 50,000 women who have had a tubal ligation. After 2 years of follow-up, the rate of in situ cervical cancer is 18 per 10,000 in the oral contraceptive group and 3 per 10,000 (p < 0.05) in the tubal ligation group. Which of the following is the estimated relative risk of cervical cancer among users of oral contraceptives as compared with women who have had a tubal ligation?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 50 min 59 sec
24. An 18-month-old boy who is "chubby" is brought to the physician's office for a routine examination. His weight is above the 90th percentile. Laboratory studies show:
Hematocrit Leukocyte count Mean corpuscular volume Platelet count
Which of the following laboratory values is most likely to be abnormal?
O € ? o r mPrevious Next Lab Values Review Help Pause
30%9000/mm3 60 pm3 650,000/mm3
Exam Section 1: Item 25 of 50■ Mark
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 49 min 57 sec
25. An 80-year-old woman comes to the physician because of a 10-year history of slowly worsening pain in both knees. She has a 20-year history of hypertension and worked as a housekeeper most of her adult life. Physical examination shows irregular bony prominences around the tibial plateau at the knee joint line bilaterally and moderate bilateral knee joint effusions. X-rays of the knees show thinned cartilage and extensive osteophyte formation. Which of the following is the earliest stage in the development of this condition?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 49 min 45 sec
26. A 19-year-old woman comes to the physician because of recurrent headaches for 3 weeks. An MRI of the brain is shown; the arrow indicates the site of an expanding lesion. Which of the following additional findings is most likely in this patient?
E xam Section 1: Item 27 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 49 m in 33 sec
27. An 18-year-old man is brought to the emergency department after injuring his left shoulder while playing lacrosse. He has pain in the shoulder and difficulty moving the involved extremity. An anteroposterior (A) and an axillary (B) x-ray of the shoulder are shown. Which of the following nerves is most likely injured?
E xam Section 1: Item 29 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 48 m in 44 sec
29. A 35-year-old man has the sudden onset of excruciating headache and loses consciousness. He has nuchal rigidity and bilateral extensor posturing. Which of the following is the most likely cause of his condition?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 48 min 29 sec
30. The prevalence of a disease is three times greater in nonwhites than in whites, but the incidence of the disease is no different in whites than it is in nonwhites. Which of the following best explains these findings?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 48 min 17 sec
31. A patient with blood group 0 undergoing an operation for repair of an aortic aneurysm is mistakenly transfused with a group A unit of packed red blood cells. He immediately goes into shock. A blood sample is markedly hemolyzed. Which of the following is the primary mechanism for the hemolysis?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 47 min 50 sec
32. A new drug has been developed that selectively blocks calcium channels at the synapse. Which of the following is the step in chemical transmission that is most likely to be disrupted?
E xam Section 1: Item 33 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 47 m in 37 sec
33. A 29-year-old man has a 1-week history of feeling dizzy. Warm water instilled into the left ear while the patient is supine elicits nystagmus with a quick phase to the left; warm water instilled into the right ear elicits no eye movements. Which of the following is the most likely site of a lesion?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 47 min 11 sec
35. A 16-year-old boy participates in a study of exercise and muscle hypertrophy. After a pretraining biopsy specimen of the quadriceps muscle is obtained, he begins a weight-lifting program to increase the mass and strength of the quadriceps muscle. After 3 months of training, a second muscle biopsy specimen is taken for histologic assessment of skeletal muscle characteristics. Compared with the pretraining sample, the post-training sample is most likely to show which of the following findings?
Number of Mitochondria
Amount of Actin per Myocyte
Total Number of Myocytes
A) 1 1B) no changeC) t no change tD) t no change no changeE) No change t tF) No change ? no changeG) No change no change tH) No change no change no change
E xam Section 1: Item 36 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 46 m in 51 sec
36. A full-term male newborn has enlargement of head circumference (3 cm greater than 99% of age range). Body weight is appropriate for gestational age. The cranial sutures are separated. Ultrasonography of the head shows enlargement of the lateral ventricles and thinning of the cerebral cortex. The newborn's maternal uncle had similar abnormalities. Further anatomic studies are most likely to show which of the following?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 46 min 40 sec
37. A 6-year-old boy has a history of chronic recurrent infections of the skin and respiratory tract caused by Staphylococcus aureus. Laboratory studies show a deficiency in phagocyte NADPH oxidase activity. Which of the following bacterial products contributes to the patient's increased susceptibility to S. aureus infection?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 46 min 30 sec
38. A 25-year-old man is brought to the emergency department after falling and dislocating his shoulder. Physical examination shows markedly extensible skin and hypermobile joints. He is at increased risk for development of which of the following?
Exam Section 1: Item 39 of 50 National Board of Medical Exam iners Tim e Rem aining:
■ Mark Com prehensive Basic Science Self-Assessment 3 hr 46 min 20 sec
39. An 80-year-old man with Parkinson disease dies after a large myocardial infarction. A t autopsy, examination of the brain will most likely show Lewy bodies prominently in which of the following labeled areas of the brain?
E xam Section 1: Item 41 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 45 m in 32 sec
41. A homeless 45-year-old man comes to the emergency department because of pain in his right foot for the past week and difficulty walking for the past 2 days. A painful subcutaneous swelling is present in the right groin. His sock is blood-encrusted. A 5-cm (2-in) wound surrounded by swelling is present on the ball of the foot. A purulent exudate containing some blood is expressed on palpation of the wound. Which of the following is the most likely cause of the groin swelling?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 45 min 19 sec
42. A 35-year-old man comes to his physician because of a 2-week history of muscle weakness and a facial rash. Examination shows periorbital edema and red-blue discoloration of the upper eyelids. There is bilateral proximal muscle weakness causing the patient difficulty getting up from a chair and climbing steps. An antinuclear antibody test is positive. Muscle biopsy shows perifascicular inflammation and muscle atrophy. Which of the following is the most likely diagnosis?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 44 min 52 sec
44. A 33-year-old man who is seropositive for HIV comes to the physician because of a lesion on his forehead for 4 weeks. He has a 10-year history of intravenous drug abuse. Physical examination shows a 1-cm, irregularly shaped, raised, indurated lesion on the forehead. A photomicrograph of a biopsy specimen of the lesion is shown. Which of the following is the most likely causal organism of this lesion?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 44 min 42 sec
45. A study is conducted to compare two drugs (X and Y) for treatment of arthritis pain. Fifty subjects are selected for the study: half are assigned to take drug X and half to take drug Y. One month later, pain relief is assessed. Following a 1-week washout period (no drug), those who took drug X are reassigned to drug Y, and those who took drug Y are reassigned to drug X. One month later, pain relief is again assessed. Pain relief with the two drugs is then compared across the 50 subjects. Which of the following best describes this study design?
E xam Section 1: Item 46 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 44 m in 32 sec
46. A 28-year-old woman comes to the physician because of the lesions shown. An x-ray of the chest shows hilar lymphadenopathy. Which of the following findings are most likely on histologic examination of a skin lesion and a hilar lymph node?
E xam Section 1: Item 47 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 44 m in 15 sec
47. A 10-year-old girl is brought to the emergency department 1 hour after she fell from her bicycle. Physical examination shows a 2-cm, deep laceration over the left forearm. As a result of the tissue trauma, which of the following plasma proteins most likely bound clotting factor XII (Hageman factor) and kininogen, allowing autocatalytic amplification of the inflammatory system in this patient?
E xam Section 1: Item 48 o f 50 N ational Board o f M ed ica l E xam iners T im e R em ain ing :
■ M ark C o m p rehensive Basic S c ience Self-Assessment 3 hr 43 m in 51 sec
48. A 17-year-old boy has anesthesia of the little finger and atrophy of the interosseous muscles 3 weeks after receiving a violent blow to the anterior axilla while playing football. Based on the diagram of the brachial plexus, which of the following labeled sites is most likely to be injured?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 43 min 42 sec
49. A randomized control trial compares the efficacy of methotrexate with that of a placebo for maintaining remission in patients with Crohn disease. The results are shown:
Methotrexate Placebo Number of patients in study group 40 36Number remaining in remission 26 (65%) 14 (39%)
These findings found an absolute risk reduction of 26.1% (95% confidence interval: 4.4% - 47.8%); p-value is 0.04. If the study randomized 1000 patients instead of 76, which of the following is the expected impact on the confidence interval?
National Board of Medical ExaminersComprehensive Basic Science Self-Assessment
Time Remaining:3 hr 43 min 24 sec
50. A 67-year-old man has had rapidly progressive memory loss, agnosia, and apraxia over the past 6 months. He had a corneal transplant 9 months ago. He has myoclonic jerking movements. Which of the following is the most likely cause of these findings?
