NBME 25 Certification Review Exam Questions With Multiple Choices And Verified Answers.

1 Exam Section 1: Item 1 of 50 National Board of Medical Examiners Comprehensive Basic Science Self-Assessment 1. A75-year-old man has decreased exercise tolerance and occasional syncopal episodes related to exertion. Left-heart catheterization discloses this pressure tracing (Ao -aorta; LV -left ventricle; LA - left atrium). The most frequently encountered mechanism underlying this disorder is which of the following? ЕCG A) Amyloid deposition 150- B) Calcification C) Cystic medial necrosis D) Pericardial effusion 100- O E) Septal hypertrophy Ao 50- LV LA Time Time- Correct Answer: B. The pressure tracing demonstrates a large pressure gradient between the left ventricle and aorta during systole, which is consistent with the diagnosis of aortic stenosis. In the setting of aortic stenosis, the left ventricle must generate higher pressures in order to overcome the opening resistance of the stenotic valve. This increased - correct answer 2 Exam Section 1: Item 2 of 50 National Board of Medical Examiners Comprehensive Basic Science Self-Assessment 2. New reagents are being designed to treat graft-versus-host disease in HLA-unrelated bone marrow transplant recipients. Reagents should be designed that selectively deplete which of the following donor cells? A) B lymphocytes O B) Dendritic cells C) Macrophages D) Neutrophils E) T lymphocytes Correct Answer: E. T lymphocytes, which are responsible for the immune attack against the recipient, should be the target of agents used to treat graft-versus-host disease (GVHD) in HLA-unrelated bone marrow transplant recipients. Prior to grafting of allogeneic stem cells in a bone marrow transplant, recipient native marrow must be completely ablated. It is then replaced with donor marrow, which recolonizes the marrow cavity. Successful transplantation results in reconstitution of the immune system with the donor's i - correct answer 3 Exam Section 1: Item 3 of 50 National Board of Medical Examiners Comprehensive Basic Science Self-Assessment 3. A9-year-old boy has had alopecia and hypocalcemia since birth. His serum 1,25-dihydroxycholecalciferol concentration is within the reference range, serum 24,25-dihydroxycholecalciferol is undetectable. Serum parathyroid hormone concentration is above the upper limit of the laboratory assay and needs to be reassayed at a dilution. The results are pending. Which of the following is the most likely cause of his condition? O A) Loss-of-function mutation in the calcium-sensing receptor B) Multiple endocrine neoplasia type I C) Mutations inactivating the vitamin D 24-hydroxylase gene D) Mutations inactivating the vitamin D receptor Correct Answer: D. Vitamin D plays a role in serum calcium and phosphate homeostasis by promoting the intestinal absorption of calcium and phosphate. Parathyroid hormone (PTH) also h - correct answer 4 Exam Section 1: Item 4 of 50 National Board of Medical Examiners® Comprehensive Basic Science Self-Assessment 4. Assuming the positive predictive value of a test is 50% and the negative predictive value is 75%, which of the following tables are consistent with these values? Disease Disease Present Absent Present Absent A B Positive 50 50 750 250 Test Negative 250 750 50 50 Positive 250 750 50 50 Test Negative 50 50 750 250 E Cannot be determined from data given A) B) C) D) E) Correct Answer: A. Positive predictive value (PPV) and negative predictive value (NPV) are statistical measurements that define the proportion of positive test results that are true positives (positive tests in patients who have the condition) and true negatives (negative tests in patients without the condition). PPV is thus defined as (true positives [TP]) / (TP + false positives [FP]) and measures the probability of a patient having the dise - correct answer 5 Exam Section 1: Item 5 of 50 National Board of Medical Examiners Comprehensive Basic Science Self-Assessment 5. A 43-year-old woman comes to the physician because of vague discomfort, nausea, easy bruising, and weight loss. Her prothrombin time is increased. The most likely cause of the increased prothrombin time is damage to which of the following cells? A) Endothelial cells B) Fibroblasts C) Нерatocytes D) Macrophages E) Skeletal muscle cells F) T lymphocytes Correct Answer: C. Hepatocyte injury accounts for this patient's symptoms and coagulation abnormality. Hepatocytes filter and detoxify portal venous blood, metabolize medications, synthesize coagulation factors (including fibrinogen, prothrombin, factors V, VII, IX, X, XI, XII, proteins C and S), complement, apoproteins, triglycerides, cholesterol, bile acids, and albumin, and play critical roles in biochemical metabolism (eg, gluconeogenesis). Many manifest - correct answer 6 Exam Section 1: Item 6 of 50 National Board of Medi