Lange Q&A: USMLE Step 1, 6th Edition

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SIXTH EDITION

LANGE Q&A

™

USMLE STEP 1 Michael W. King, PhD Professor Department of Biochemistry and Molecular Biology Center for Regenerative Biology and Medicine Indiana University School of Medicine Terre Haute, Indiana

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Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-164314-1 The material in this eBook also appears in the print version of this title: 0-07-149219-4. All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. Where such designations appear in this book, they have been printed with initial caps. McGraw-Hill eBooks are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please contact George Hoare, Special Sales, at [email protected] or (212) 904-4069. TERMS OF USE This is a copyrighted work and The McGraw-Hill Companies, Inc. (“McGraw-Hill”) and its licensors reserve all rights in and to the work. Use of this work is subject to these terms. Except as permitted under the Copyright Act of 1976 and the right to store and retrieve one copy of the work, you may not decompile, disassemble, reverse engineer, reproduce, modify, create derivative works based upon, transmit, distribute, disseminate, sell, publish or sublicense the work or any part of it without McGraw-Hill’s prior consent. You may use the work for your own noncommercial and personal use; any other use of the work is strictly prohibited. Your right to use the work may be terminated if you fail to comply with these terms. THE WORK IS PROVIDED “AS IS.” McGRAW-HILL AND ITS LICENSORS MAKE NO GUARANTEES OR WARRANTIES AS TO THE ACCURACY, ADEQUACY OR COMPLETENESS OF OR RESULTS TO BE OBTAINED FROM USING THE WORK, INCLUDING ANY INFORMATION THAT CAN BE ACCESSED THROUGH THE WORK VIA HYPERLINK OR OTHERWISE, AND EXPRESSLY DISCLAIM ANY WARRANTY, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise. DOI: 10.1036/0071492194

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Contents

Contributors ........................................................................................................................................................... v Preface .................................................................................................................................................................. vii Review Preparation Guide ................................................................................................................................ ix Standard Abbreviations ................................................................................................................................... xiii USMLE Step 1 Common Laboratory Values ................................................................................................. xv 1. Anatomy ........................................................................................................................................................... 1 TAIHUNG DUONG, PHD

Questions .......................................................................................................................................................... 1 Answers and Explanations .......................................................................................................................... 30 Bibliography ................................................................................................................................................... 55 2. Physiology ..................................................................................................................................................... 57 GABI NINDL WAITE, PHD, BRIAN G. KENNEDY, PHD, AND STEPHEN ECHTENKAMP, PHD

Questions ......................................................................................................................................................... 57 Answers and Explanations ........................................................................................................................... 82 Bibliography .................................................................................................................................................. 108 3. Biochemistry ............................................................................................................................................... 109 MICHAEL W. KING, PHD

Questions ....................................................................................................................................................... 109 Answers and Explanations ......................................................................................................................... 132 Bibliography .................................................................................................................................................. 174 4. Microbiology ............................................................................................................................................... 175 JAMES D. KETTERING, PHD

Questions ....................................................................................................................................................... 175 Answers and Explanations ......................................................................................................................... 198 Bibliography .................................................................................................................................................. 228 5. Pathology ..................................................................................................................................................... 229 KAREN D. TSOULAS, MD, EDD

Questions ....................................................................................................................................................... 229 Answers and Explanations ......................................................................................................................... 256 Bibliography .................................................................................................................................................. 288 iii

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Contents

6. Pharmacology............................................................................................................................................... 289 BERTRAM G. KATZUNG, MD, PHD

Questions ....................................................................................................................................................... 289 Answers and Explanations ......................................................................................................................... 307 Bibliography .................................................................................................................................................. 333 7. Behavioral Sciences .................................................................................................................................... 335 HOYLE LEIGH, MD

Questions ....................................................................................................................................................... 335 Answers and Explanations ......................................................................................................................... 342 Bibliography .................................................................................................................................................. 348 8. Practice Test 1 ............................................................................................................................................... 349 Questions ....................................................................................................................................................... 349 Answers and Explanations ......................................................................................................................... 359 Bibliography .................................................................................................................................................. 371 9. Practice Test 2 ............................................................................................................................................... 373 Questions ....................................................................................................................................................... 373 Answers and Explanations ......................................................................................................................... 382 10. Practice Test 3 ............................................................................................................................................... 395 Questions ....................................................................................................................................................... 395 Answers and Explanations ......................................................................................................................... 404 11. Practice Test 4 ............................................................................................................................................... 417 Questions ....................................................................................................................................................... 417 Answers and Explanations ......................................................................................................................... 426 12. Practice Test 5 ............................................................................................................................................... 439 Questions ....................................................................................................................................................... 439 Answers and Explanations ......................................................................................................................... 449 13. Practice Test 6 ............................................................................................................................................... 461 Questions ....................................................................................................................................................... 461 Answers and Explanations ......................................................................................................................... 470 14. Practice Test 7 ............................................................................................................................................... 481 Questions ....................................................................................................................................................... 481 Answers and Explanations ......................................................................................................................... 491 Index ..................................................................................................................................................................... 503 Color insert appears after the Index.

Contributors

Taihung Duong, PhD

James D. Kettering, PhD

Associate Professor Department of Anatomy and Cell Biology Indiana University School of Medicine-Terre Haute Terre Haute, Indiana

Professor Emeritus Department of Biochemistry and Microbiology Loma Linda University School of Medicine Loma Linda, California

Stephen Echtenkamp, PhD

Hoyle Leigh, MD

Associate Professor Department of Cellular and Integrative Physiology Indiana University School of Medicine-Northwest Gary, Indiana

Professor Department of Psychiatry University of California, San Francisco Fresno, California

Bertram G. Katzung, MD, PhD

Karen D. Tsoulas, MD, EdD

Professor Emeritus Department of Cellular and Molecular Pharmacology University of California, San Francisco San Francisco, California

Assistant Professor Department of Pathology and Laboratory Medicine Keck School of Medicine University of Southern California Los Angeles, California

Brian G. Kennedy, PhD Associate Professor Department of Cellular and Integrative Physiology Indiana University School of Medicine-Northwest Gary, Indiana

Gabi Nindl Waite, PhD Associate Professor Department of Cellular and Integrative Physiology Indiana University School of Medicine-Terre Haute Terre Haute, Indiana

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Preface

Success on the United States Medical Licensing Examination (USMLE) Step 1 requires a thorough understanding of the basic sciences covered in the first and second years of medical education. To offer the most complete and accurate review book, we assembled a team of authors and editors from around the country who are engaged in various specialties and involved in both academic and clinical settings. The author team was asked to research and write test questions using the parameters set forth by the National Board of Medical Examiners (NBME). All the subjects, types of questions, and techniques that will be encountered on the USMLE Step 1 are presented in this book. Lange Q&A: USMLE Step 1 is designed to provide you with a comprehensive review of the basic sciences as well as a valuable self-assessment tool for exam preparation. A total of 1200 questions are included in this edition.

Key Features and Use

• Approximately 150 questions are covered in each of the basic sciences: Anatomy, Physiology, Biochemistry, Microbiology, Pathology, Pharmacology, and Behavioral Sciences. • Questions are followed by a section with answers and detailed explanations referenced to the most current and popular resources available. • Seven practice tests simulating the USMLE Step 1 are included at the end of this text. • We believe that you will find the questions, explanations, and format of Lange Q&A: USMLE Step 1 to be of great assistance to you during your review. We wish you luck on the USMLE Step 1. The Editor and the Publisher

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Review Preparation Guide

If you are planning to prepare for the USMLE Step 1, then this book is designed for you. Here, in one package, is a comprehensive review resource with 1200 examination-type basic science, multiplechoice questions with referenced, paragraph-length explanations of each answer. In addition, the last section of the book offers seven comprehensive practice tests for self-assessment purposes. This introduction provides specific information on the USMLE Step 1, information on question types, question-answering strategies, and various ways to use this review.

The USMLE Step 1

The USMLE Step 1 has approximately 350 multiplechoice test items, divided into seven blocks of 50 questions, which are administered via computer. Students are allotted 1 hour to complete each question block. The exam is designed to test knowledge of Anatomy, Physiology, Biochemistry, Microbiology, Pathology, Pharmacology, and Behavioral Sciences. The questions have been proffered by senior academic faculty to test comprehension of basic science concepts that they feel are relevant to the future successful practice of medicine. To correctly answer these test questions, examinees may be required to recall memorized facts, to use deductive reasoning, or both. A minority of the questions will employ graphs, photographs, or line drawings that require interpretation. The application materials you receive for the USMLE Step 1 will more fully discuss the exam procedure, rules of test administration, types of questions asked, and the scope of material you may be tested on.

Organization of this Book

This book is organized to cover sequentially each of the basic science areas specified by the National Board of Medical Examiners. There are seven sections, one for each of the basic sciences, plus three integrated practice tests at the end of the review. The sections are as follows: 1. Anatomy (including gross and microscopic anatomy, neuroanatomy, and development and control mechanisms). 2. Physiology (including general and cellular functions, major body system physiology, energy balance, and fluid and electrolyte balance). 3. Biochemistry (including energy metabolism, major metabolic pathways of small molecules, major tissue and cellular structures, properties, and functions, biochemical aspects of cellular and molecular biology, and special biochemistry of tissues). 4. Microbiology (including microbial structure and composition, cellular metabolism, physiology, and regulation, microbial and molecular genetics, immunology, bacterial pathogens, virology, and medical mycology and parasitology). 5. Pathology (including general and systemic pathology and pathology of syndromes and complex reactions). 6. Pharmacology (including general principles, major body system agents, vitamins, chemotherapeutic agents, and poisoning and therapy of intoxication). 7. Behavioral Sciences (including behavioral biology, individual, interpersonal, and social behavior, and culture and society).

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x

Review Preparation Guide

8. Practice Tests (each includes 50 questions from all seven basic sciences, presented in an integrated format). Each of the chapters is organized in the following order: Questions, Answers and Explanations, and Bibliography. These sections and how you might use them are discussed below. Question Formats The style and presentation of the questions have been fully revised to conform to the USMLE Step 1. This will enable you to familiarize yourself with the types of questions to be expected, and provide practice in recalling your knowledge in each format. Following the answers in each chapter is a list of suggested references for additional consultation. Each of the seven basic science chapters contains multiple choice questions composed in the Single Best Answer query format (example question 1). This is the most frequently encountered format in the USMLE Step 1. It generally contains a brief statement, followed by five options of which only one is entirely correct. The answer options on the USMLE are lettered A, B, C, D, and E. Although the format for this question type is straightforward, the questions can be difficult because some of the distractors in the answer list are partially correct. An example of this question format follows: DIRECTIONS (Question 1): Each of the numbered items or incomplete statements in this section is followed by answers or by completions of the statement. Select the one lettered answer or completion that is best in each case. 1. Liquefaction necrosis is the characteristic result of infarcts in the (A) (B) (C) (D) (E)

brain heart kidney spleen small intestine

The correct answer is (A). There are two ways to attack this style of question. If after reading the query an answer immediately comes to mind, then look for it in the answer list. Alternatively, if no answer immediately comes to mind, or if the answer

you thought was obvious is not a choice, then you will need to spend time examining all of the answer options to find the correct one. In this case, anything you can do to eliminate an answer option will increase your odds of choosing the correct answer. With this in mind, scan all of the possible answers. Eliminate any that are clearly wrong and all that are only partially right. Even if you can eliminate one or two of the answer choices by this method you will have significantly increased your chance of guessing the right answer from the remaining choices. Always answer every question, even if you have to guess among all five answer choices, because there is no penalty for a wrong answer. Your test score is dependent only on the number of correct answers obtained. Strategies for Answering Single Best Answer Questions 1. Remember that only one choice can be the correct answer. 2. Read the question carefully to be sure that you understand what is being asked. 3. If you immediately know the answer, look for it in the answer choices. 4. If no answer is immediately obvious, quickly scan all the five answer choices for familiarity. 5. Eliminate any answer that is completely wrong or only partially correct. This increases your odds of picking the correct answer from a lesser number of remaining answer choices. 6. If two of the remaining choices are mutually exclusive, the correct answer is probably one of them. 7. Always answer every question even if you have to guess. 8. Don’t spend too much time with any one question. To finish each 60-minute session you will need to answer a question about every 70 seconds. Practice Tests The seven 50-question practice tests at the end of the book consist of questions from each of the seven basic sciences. This format mimics the actual exam and enables you to test your skill at answering questions in all of the basic sciences under simulated examination conditions.

Review Preparation Guide

The practice test section is organized in a similar format as the seven earlier sections: Questions, Answers and Explanations, and a Subject List. The Bibliogrpahy for the practice tests is at the end of Chapter 14.

How to Use this Book

There are two logical ways to get the most value from this book. We will call them Plan A and Plan B. In Plan A, you go straight to the Practice Tests and complete them according to the instructions. This will be a good indicator of your initial knowledge of the subject and will help you identify specific areas for preparation and review. You can now use the first seven chapters of the book to help you improve your relative weak points. In Plan B, you go through Chapters 1 through 7 checking off your answers and then comparing your choices with the answers and discussions in the book. Once you have completed this process, you can take the Practice Tests and see how well prepared you are. If you still have a major weakness, it should be apparent in time for you to take remedial action. In Plan A, by taking the Practice Tests first, you get quick feedback regarding your initial areas of strength and weakness. You may find that you have a good command of the material, indicating that perhaps only a cursory review of the seven chapters is necessary. This, of course, would be good to know early on in your exam preparation. On the other hand, you may find that you have many areas of weakness. In this case, you could then focus on these areas in your review not just with this book, but also with the cited references and with your current textbooks. It is, however, unlikely that you will not do some studying prior to taking the USMLE (especially since you have this book). Therefore, it may be more realistic to take the Practice Tests after you have reviewed the first seven chapters (as in Plan B). This will probably give you a more realistic type of testing situation since very few of us just sit down to a test without studying. In this case, you will have done some reviewing (from superficial to in-depth), and your Practice Tests will reflect this studying time. If, after reviewing the first seven chapters and

xi

taking the Practice Tests, you still have some weaknesses, you can then go back to the first seven chapters and supplement your review with your texts.

Specific Information on the Step 1 Examination

The official source of all information with respect to the United States Medical Licensing Examination Step 1 is the National Board of Medical Examiners (NBME), 3930 Chestnut Street, Philadelphia, PA 19104 (www.nbme.org). Established in 1915, the NBME is a voluntary, nonprofit, independent organization whose sole function is the design, implementation, distribution, and processing of a vast bank of question items, certifying examinations, and evaluative services in the professional medical field. You should contact the NBME directly for information regarding eligibility to sit for the USMLE, or visit the USMLE web site at www.usmle.org. Scoring Because there is no deduction for wrong answers, you should answer every question. Your test is scored in the following way: 1. The number of questions answered correctly is totaled. This is called the raw score. 2. The raw score is converted statistically to a “standard” score on a scale of 200–800, with the mean set at 500. Each 100 points away from 500 is one standard deviation. 3. Your score is compared statistically with the criteria set by the scores of the second-year medical school candidates for certification in the June administration during the prior 4 years. This is what is meant by the term, “criterion referenced test.” 4. A score of 500 places you around the 50th percentile. A score of 380 is the minimum passing score for Step 1; this probably represents about the 12th to 15th percentile. If you answer 50 percent or so of the questions correctly, you will probably receive a passing score. Remember: You do not have to pass all seven basic science components, although you will receive

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Review Preparation Guide

a standard score in each of them. A score of less than 400 (about the 15th percentile) on any particular area is a real cause for concern as it will certainly drag down your overall score. Likewise, a 600 or better (85th percentile) is an area of great relative strength. (You can use the practice test included in this book to help determine your areas of strength and weakness well in advance of the actual examination.)

Physical Conditions The NBME is very concerned that all their exams be administered under uniform conditions in the numerous centers that are used. Since 1999, the USMLE examination has been administered electronically. Please visit www.nmbe.org for details, or contact your local Prometric center for scheduling and further information.

Standard Abbreviations

ACTH: ADH: ADP: AFP: AMP: ATP: ATPase:

adrenocorticotropic hormone antidiuretic hormone adenosine diphosphate alpha-fetoprotein adenosine monophosphate adenosine triphosphate adenosine triphosphatase

bid: BP: BUN:

two times a day blood pressure blood urea nitrogen

CT: CBC: CCU: CNS: CPK: CSF:

computed tomography complete blood count coronary care unit central nervous system creatine phosphokinase cerebrospinal fluid

DNA: deoxyribonucleic acid DNAse: deoxyribonuclease ECG: EDTA: EEG: ER:

electrocardiogram ethylenediaminetetraacetate electroencephalogram emergency room

FAD: FSH:

flavin adenine dinucleotide follicle-stimulating hormone

GI: GU:

gastrointestinal genitourinary

Hb: hCG: HDL: Hct:

hemoglobin human chorionic gonadotropin high-density lipoprotein hematocrit

IgA, etc.: IM: IQ: IU: IV:

immunoglobulin A, etc. intramuscular(ly) intelligence quotient international unit intravenous(ly)

KUB:

kidney, ureter, and bladder

LDH: LDL: LH: LSD:

lactic dehydrogenase low-density lipoprotein luteinizing hormone lysergic acid diethylamide

mRNA:

messenger RNA

NAD: NADP:

nicotinamide adenine dinucleotide nicotinamide adenine dinucleotide phosphate

PO: prn:

oral(ly) as needed

RBC: RNA: RNAse: rRNA:

red blood cell ribonucleic acid ribonuclease ribosomal RNA

SC: SGOT: SGPT:

subcutaneous(ly) serum glutamic oxaloacetic transaminase serum glutamic pyruvic transaminase

TB: tRNA: TSH:

Tuberculosis transfer RNA thyroid-stimulating hormone

WBC:

white blood cell

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USMLE STEP 1 COMMON LABORATORY VALUES

BLOOD, PLASMA, SERUM * Alanine aminotransferase (ALT, GPT at 30 EC) Alpha-fetoprotein Amylase, serum * Aspartate aminotransferase (AST, GOT at 30 EC) Bilirubin, serum (adult) Total // Direct * Calcium, serum (Ca2+) * Cholesterol, serum * Cortisol, serum * Creatine kinase, serum * Creatinine, serum Electrolytes, serum Sodium (Na+) Chloride (Cl–) * Potassium (K+) Bicarbonate (HCO3−) Magnesium (Mg2+) Estriol, total, serum (in pregnancy) 24–28 weeks // 32–36 weeks 28–32 weeks // 36–40 weeks Ferritin, serum Follicle-stimulating hormone, serum/plasma

Gases, arterial blood (room air) pH PCO2 PO2 * Glucose, serum Growth hormone—arginine stimulation Immunoglobulins, serum IgA IgE IgG IgM Iron Lactate dehydrogenase, serum Luteinizing hormone, serum/plasma

Osmolality, serum Parathyroid hormone, serum, N-terminal * Phosphatase (alkaline), serum (P-NPP at 30 EC) * Phosphorus (inorganic), serum Prolactin, serum (hPRL) * Proteins, serum Total (recumbent) Albumin Globulin Thyroid-stimulating hormone, serum or plasma Thyroidal iodine (123I) uptake Thyroxine (T4), serum Triglycerides, serum

REFERENCE RANGE

SI REFERENCE INTERVALS

8–20 U/L Adult: 3.9 ng/mL) occur in up to half of patients with benign prostatic hyperplasia, and a significant number of patients with prostate CA have normal levels of PSA, regardless of clinical stage. PSA has, however, demonstrated value as a marker for monitoring prostate CA therapy (e.g., post-radical prostatectomy). 42. (A) Creatine and the energy reserve form phosphocreatine are present in skeletal muscle, brain, and blood. Creatine synthesis begins in the kidney from arginine and glycine. The products of the first reaction are ornithine and guanidoacetate. Guanidoacetate is transported to the liver, where it is converted to creatine by methylation from S-adenosylmethionine. Phosphorylation of creatine is carried out by creatine kinase (CK). CK plays an important role in the reversible transfer of phosphate from ATP to creatine when energy levels are high, and then from creatine to ADP when energy levels fall and demand for energy is high. Creatine can spontaneously cyclize to creatinine. Creatinine clearance by any given individual is amazingly constant from day to day and is proportional to muscle mass. None of the other amino acid choices (B, C, D, and E) are involved in creatine synthesis. 43. (B) Epstein-Barr virus is a B-cell-specific oncogenic organism that is responsible for Burkitt lymphoma that features a myc gene translocation. Arenaviruses (choice A) have sand-like particles (arena) on their surface and cause such diseases as the fatal hemorrhagic fever (Lassa fever) and lymphocytic choriomeningitis. Poliovirus (choice C) is associated with poliomyelitis. Rhabdoviruses (choice D), such as the rabies virus, can cause hallucinations, delirium, hydrophobia, coma, and death. Rotavirus (choice E) is the common cause of infantile diarrhea.

Answers: 39–50

44. (B) The parenchyma of the kidney containing the nephrons (glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, and distal tubule) develops from the metanephric mass of intermediate mesoderm. The metanephric diverticulum (choice A) gives rise to the ureter, renal pelvis, major and minor calyces, and collecting tubules. The notochord (choice C) is an embryonic structure, which participates in the formation of the central nervous system and not in the urinary system. The paramesonephric ducts (choice D) form the female uterine tubes and only participate in the formation of the female reproductive system. The pronephroi (choice E) are a transitory set of nonfunctional kidneys during the embryonic development. 45. (E) Stimulus generalization is a process through which a conditioned response is transferred from one stimulus to another stimulus that, in some sense, resembles the conditioned stimulus. In this case, the patient generalized the conditioned stimulus from bees to other flying objects—flies and birds. Classical conditioning (choice A), flooding (choice B), operant conditioning (choice C), and shaping (choice D) refer to other aspects of learning. 46. (C) In emphysema there is marked loss of elastic fibers, causing an increase in lung compliance. Physiological dead space is a function of all lung areas that do not contribute optimally to gas exchange. Elastic tissue helps to keep airways open. With a loss of elastic tissue, airways thus tend to collapse with a resultant increase in airway resistance (choice A). Because of increased lung compliance, functional residual capacity is increased (choice B). Loss of alveolar walls in emphysema causes the surface to volume ratio of the alveoli to decrease, thus impairing gas exchange. There is thus an increase in physiological dead space (choice D). Increased tendency of airways and alveoli to collapse also increases residual volume (choice E) since there is more air trapping in the lungs. 47. (C) Imipramine is a weak base with a pKa value of 9.5. The unprotonated form is uncharged

437

and is the permeant species that crosses biological membranes. At equilibrium, the concentration of the permeant species is the same on both sides of the membrane, but the total amount (base + protonated form) present in each compartment depends on the pH of the compartment. For a weak base, the total amount is highest in the most acidic compartment. This is because lower pH values cause protonation of the base to the charged form and the charged base cannot cross the membrane. The lower the pH value for the compartment, the greater the total amount of drug present. Stomach contents at pH 2.0 have the lowest pH value. The value for the total amount at any pH may be calculated using the Henderson–Hasselbalch equation [log (protonated form/unprotonated form = pKa –pH)]. 48. (E) Epstein-Barr virus (EBV) has been implicated in the pathogenesis of nasopharyngeal carcinoma (NPC) and certain B-cell malignancies (Burkitt, Hodgkin lymphoma, lymphomas in immunocompromised patients). EBV DNA has been reported in virtually all cases of nasopharyngeal carcinoma cases worldwide. Although rare in the United States, NPC has a strikingly high incidence in southern China; certain areas in Africa and the Middle East also have a high incidence. Focal geographic distribution suggests a possibility that environmental or genetic cofactors, in addition to EBV, have a role in the pathogenesis of NPC. While alcohol consumption (choice A) and cigarette smoking (choice D) are both associated with several types of cancer, neither has an association with NPC. Asbestos exposure (choice C) increases the risk of mesothelioma. Allergic rhinitis (choice B) is a hypersensitivity type I immune reaction and is not associated with NPC. 49. (B) While all the other items (choices A, C, D, and E) are components of personality, patterns of thought, behavior, and feelings combined is the most comprehensive. 50. (B) Maturity onset type diabetes of the young (MODY) was previously considered to be a third form of Type II diabetes. However, with the discovery of specific mutations leading to MODY, it

438

11: Practice Test 4

is now classified under secondary or other specific types of diabetes. MODY is characterized by onset prior to age 25. All cases to date have shown impaired beta-cell function. Patients may also exhibit insulin resistance and late beta-cell failure. Evidence indicates that mutations in 10–12 different genes have been correlated with the development of MODY with 6 forms being well characterized as to the defective gene. MODY2 results from defects in pancreatic

glucokinase. Von Gierke disease is caused by defects in glucose-6 phosphatase (choice A) Defects in glycogen phosphorylase (choice C) lead to hepatic (Hers) or muscle (McArdle) glycogen storage diseases. MODY3 is caused by defects in the transcription factor HNF-1-alpha (choice D). MODY4 is caused by defects in the homeodomain transcription factor insulin promoter factor-1 (choice E), more commonly called PDX1 derived from pancreas duodenum homeobox-1.

CHAPTER 12

Practice Test 5 Questions 1. Which of the following drugs is the current drug of choice for treatment of trichinosis (Trichinella spiralis) infections? (A) (B) (C) (D) (E)

dehydroemetine diloxanide mebendazole metronidazole praziquantel

2. A 35-year-old woman presents with a complaint of missing her last two menstrual cycles after having regular menstrual cycles for the last 5 years. She denies having headaches, double vision, or facial numbness. For the last 3 months, she is treating her gastroesophageal reflux disease by taking a prokinetic medicine, which acts by being a dopaminergic antagonist. Human chorionic gonadotropin is not detected in her blood. Serum TSH levels are normal. Which of the following is the most likely cause of her developing amenorrhea? (A) (B) (C) (D) (E)

apolipoprotein(a) (apo[a]). Apo(a) is associated with LDL via a disulfide linkage to which other apolipoprotein? (A) (B) (C) (D) (E)

4. A 39-year-old woman undergoes a total hysterectomy and a section of her left fallopian tube is shown in Figure 12-1. What is the most likely diagnosis?

high prolactin levels low prolactin levels menopause pregnancy subclinical hypothyroidism

3. High plasma levels of the lipoprotein particle identified as lipoprotein(a) [Lp(a)] has been shown to be a primary risk factor for coronary heart disease and stroke. Lp(a) is a unique lipoprotein assembled from low-density lipoprotein (LDL) and a single glycoprotein called

Apo AI Apo B48 Apo B100 Apo CII Apo E

FIG. 12-1 (Also see color insert.)

(A) (B) (C) (D) (E)

chronic salpingitis ectopic tubal pregnancy endometriosis endosalpingiosis serous papillary carcinoma

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440

12: Practice Test 5

5. A 45-year-old woman is admitted to the ER with a chief complaint of substernal chest pain. An ECG shows marked cardiac ischemia. She has no prior history of cardiovascular disease but sees a physician regularly regarding severe migraine headache. Which of the following drugs has been used in migraine and has been associated with coronary vasospasm? (A) (B) (C) (D) (E)

acetaminophen ergonovine ibuprofen propranolol naproxen

6. A 33-year-old male patient returns from a 6-year tour of navy duty where he was stationed in Thailand. The patient presents with impairment of proprioception and vibratory sensation along with loss of deep tendon reflexes. When the patient walks or stands, he maintains a wide-base gait due to his sensory ataxia. When asked to stand feet together with his eyes closed, he displays Romberg’s sign (unsteady, swaying posture). He is diagnosed with tabes dorsalis due to tertiary neurosyphilis. What is the most likely location of this lesion? (A) (B) (C) (D) (E)

anterolateral system of the spinal cord basal ganglia cerebellum dorsal columns of the spinal cord ventral horns of the spinal cord

Questions 7 through 9 A 28-year-old woman is brought to the hospital because she had not come out of her room for 3 days, missing work. She would eat only when a tray was brought in. 7. Which of the following drugs might be used intravenously to reverse the mutism and immobility? (A) amitriptyline (B) fluoxetine (C) lorazepam

(D) risperidone (E) sertraline 8. Further history reveals that the patient had her first psychiatric hospitalization at age 20 when she made a suicide attempt. Otherwise, she is known to be a rather cheerful person. She is gainfully employed, but there are times when she has shopping sprees running up enormous credit card debt. There seems to be no history of substance abuse. Family history reveals that her maternal grandmother had died in a state hospital. Which of the following is the most likely diagnosis for this patient? (A) (B) (C) (D) (E)

bipolar disorder delusional disorder folie à deux lewy body disease schizophrenia

9. Given the most likely diagnosis above, which of the following would be the drug of choice? (A) (B) (C) (D) (E)

benztropine chlordiazepoxide fluoxetine tranylcypromine valproic acid

10. A 24-year-old man complains of a urethral discharge and painful urination. A gram-stain smear of the discharge shows many pus cells (neutrophils) but no bacteria. Of the following organisms, which is the one most likely to cause the discharge? (A) (B) (C) (D) (E)

Neisseria gonorrhoeae Staphylococcus aureus Streptococcus pyogenes Treponema pallidum Ureaplasma urealyticum

11. A 12-month-old female exhibits severe developmental delay with associated macrocephaly, dysmorphic facies, hypotonia, and hepatosplenomegaly. Clouding of the corneas is not evident. A pebbly ivory-colored lesion is

Questions: 5–17

present over the infant’s back. The activity of iduronate sulfatase in the plasma is not detectable. These symptoms are indicative of which mucopolysaccharidosis? (A) (B) (C) (D) (E)

hunter hurler Maroteaux-Lamy Morquio B Sanfilippo A

Questions 12 and 13 12. In a skateboard accident, a young female patient has bitten severely into her tongue on the left side and bleeds profusely. A surgical resident tries to locate the lingual artery in order to clamp it, prior to surgical repair of the tongue. The normal location for this artery in the mouth is which of the following? (A) between the buccinator muscle and the teeth (B) between the lingual nerve and the submandibular duct (C) lateral to the hyoglossus muscle, but medial to the lingual nerve (D) lateral to the submandibular duct and the lingual nerve (E) medial to the lingual nerve and the hyoglossus muscle 13. In the same patient, it is observed that the left opening of the submandibular duct atrophies over the next several days. The attending physician worries that the parasympathetic innervation has been injured. Of the following, which specific nerve carries the preganglionic parasympathetic innervation from the brain to the submandibular ganglion? (A) (B) (C) (D) (E)

chorda tympani hypoglossal nerve inferior alveolar nerve lingual nerve buccal nerve

14. An 87-year-old woman with vitamin C deficiency sustains a laceration on her left forearm.

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Her wound site is most likely to demonstrate which of the following? (A) (B) (C) (D) (E)

chronic infection excessive tissue necrosis keloid formation pallor due to ischemia poor wound healing

15. Which of the following is useful in the treatment of generalized anxiety disorder with the lowest incidence of sedation? (A) (B) (C) (D) (E)

alprazolam amitriptyline buspirone clozapine methylphenidate

16. A 68-year-old woman with a long history of alcoholism and chronic obstructive pulmonary disease presents to her primary care physician complaining of a recent fever, excessive and occasionally blood-streaked sputum production, a 10-lbs weight gain over the past 6 weeks, easy fatigability, bruising, and the formation of facial hair. Which of the following conditions would best explain this constellation of findings? (A) (B) (C) (D) (E)

chronic pancreatitis lung cancer new onset of diabetes mellitus pancreatic insulinoma Stein-Leventhal syndrome

17. A patient is diagnosed with problems in emptying the gallbladder. On a blood check-up, one hormone/peptide that is known to stimulate gallbladder contraction is inappropriately low. Which is the most likely one to cause the symptoms? (A) (B) (C) (D) (E)

cholecystokinin estrogen pancreatic polypeptide somatostatin vasoactive intestinal peptide

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18. A57-year-old man has abdominal surgery for the removal of a 3.2 × 4.4 cm retroperitoneal mass that was originally identified on CT scan. Microscopic examination of the lesion reveals poorly differentiated, highly pleomorphic cells arranged in a disorganized pattern. A few mitotic figures and tumor giant cells are noted and a moderate lymphocytic infiltrate is present. Immunohistochemistry is positive for S-100 protein and negative for vimentin. Based on these findings, this lesion is best classified as which of the following malignancies? (A) (B) (C) (D) (E) (F)

adenocarcinoma B-cell lymphoma liposarcoma melanoma rhabdomyosarcoma T-cell lymphoma

19. Which of the following class of hypoglycemiainducing drugs, used in the treatment of Type II diabetes, functions by activating the peroxisome proliferator-activated receptor-gamma (PPAR-gamma) proteins? (A) (B) (C) (D)

biguanides meglitinides sulfonylureas thiazolidinediones

20. Which of the following correctly matches an antiepileptic agent with its primary toxicity? (A) (B) (C) (D) (E)

carbamazepine—trigeminal neuralgia ethosuximide—gingival hyperplasia lamotrigine—life-threatening dermatitis phenytoin—photosensitivity valproic acid—sedation

21. A 3-year-old girl who has not been immunized against the usual childhood viral diseases has fever, running nose, conjunctivitis, rash, a hacking cough, and red based, blue-white centered lesion in her mouth. Which of the following is most likely the virus responsible for this girl’s symptoms? (A) adenovirus (B) corona virus (C) hantavirus

(D) measles virus (E) orthomyxovirus 22. A 64-year-old man dies following a long history of multiple myeloma. H- and E-stained sections of tissues taken at autopsy reveal acellular, eosinophilic deposits around blood vessels and in many organs. Which of the following staining methods would be most useful in confirming a diagnosis in this case? (A) (B) (C) (D) (E)

Congo red methenamine silver mucicarmine periodic acid-Schiff Prussian blue

23. An elderly homeless woman is brought to the hospital with yellowish color of her skin. From her somewhat incoherent story, it can be determined that she has consumed substantial amounts of alcohol over the past 3 decades. The physician made the diagnosis of alcoholic liver cirrhosis, associated with extensive liver fibrosis. Which of the following changes in plasma and urinary levels of bilirubin are most likely? Unconjugated Bilirubin in Plasma

Conjugated Bilirubin in Plasma

Conjugated Bilirubin in Urine

(A) (B)

decrease decrease

decrease increase

(C) (D) (E)

increase increase no change or increase

decrease no change or increase decrease no change increase

increase increase increase

24. An eruption of shingles over the cutaneous distribution of the ophthalmic nerve (herpes zoster ophthalmicus) is a common and often painful affliction. Your patient has involvement over the dorsum of the nose extending to the tip. Which of the following cutaneous branches of the ophthalmic nerve is involved? (A) (B) (C) (D) (E)

external nasal nerve lacrimal nerve supraorbital nerve supratrochlear nerve zygomaticotemporal nerve

Questions: 18–29

25. A 35-year-old woman noticed a slowly growing mass in her left breast over the past 4 months. At surgery, the mass was found to be predominantly solid, tan-white, rubbery, well circumscribed, and measuring about 3 × 3 × 3 cm. A representative photomicrograph of the lesion is displayed in Figure 12-2. Which of the following is the most likely diagnosis?

(A) (B) (C) (D) (E)

(A) (B) (C) (D) (E)

fibroadenoma intraductal carcinoma medullary carcinoma paget disease of the breast scirrhous carcinoma

26. Which of the following drugs can be used to treat or prevent severe chemotherapy-induced emesis, motion sickness, dystonias, and hay fever? (A) (B) (C) (D) (E)

diphenhydramine diphenoxylate metoclopramide ondansetron scopolamine

27. Glucagon-mediated phosphorylation leads to a decrease in the activity of which of the following enzymes of lipid metabolism?

acetyl-CoA carboxylase carnitine palmitoyltransferase I fatty acid synthase beta-ketothiolase medium-chain acyl-CoA dehydrogenase

28. A 61-year-old man with a history of left atrial fibrillation has a massive stroke and dies the following day. Autopsy findings include left atrial hypertrophy with a large mural thrombus, and mitral stenosis. The history and autopsy findings are most compatible with a diagnosis of which of the following? (A) (B) (C) (D) (E)

FIG. 12-2 (Also see color insert.)

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cardiac amyloidosis chronic interstitial lung disease dilated cardiomyopathy hypertrophic cardiomyopathy rheumatic heart disease

29. A well-nourished 21-year old woman presents with hypocalcemia. Her blood concentration of parathyroid hormone (PTH) is 150 pg/mL (normal 10–65 pg/mL). Her blood concentration of 1,25-dihydroxycholecalciferol is normal. Her BUN is normal. She is treated with a synthetic version of human PTH, and her blood calcium concentration normalizes. Which of the following is most likely causing her hypocalcemia? (A) decrease in total number of PTH receptors in kidney (B) deficiency of 1-alpha-hydroxylase activity in kidney (C) hepatocellular defect (D) secretion of an inactive PTH hormone molecule (E) severe vitamin D deficiency

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30. Paramytonia congenita (PC) is a hereditary muscle disorder characterized by severe muscle stiffness that leads to weakness or even paralysis. Pathology is due to a missense mutation in the muscle voltage gated sodium channel which slows channel inactivation. Failure to repolarize causes prolonged muscle contraction (stiffness). This can eventually lead to muscle fatigue (weakness) and transitory paralysis. Which molecular change will occur during a bout of PC? (A) decreased Ca2+-ATPase activity in the muscle (B) decreased Na+, K+-ATPase activity in the muscle (C) depletion of acetylcholine in the presynaptic terminal (D) elevation of myoplasmic sodium concentration (E) lowering of myoplasmic chloride concentration 31. Stool culture from a 19-year-old college student with diarrhea reveals a motile, microaerophilic gram-negative rod that is isolated by incubation at 41oC on medium containing antibiotics. Which of the following is most likely the organism? (A) (B) (C) (D) (E)

Campylobacter jejuni Escherichia coli Proteus vulgaris Vibrio parahaemolyticus Yersinia enterocolitica

32. A 57-year-old male patient presents with progressive weakness of the upper and lower limbs. Atrophy of the muscles of the upper limb is observed. Neurologic examination reveals slight spasticity of the legs and generalized hyperreflexia. The patient displays Babinski sign in both lower extremities. All sensory modalities are intact and cerebellar tests are normal. A magnetic resonance (MR) scan confirms that the patient suffers from amyotrophic lateral sclerosis. Which of the following structures is most likely lesioned in this disorder? (A) corticospinal tract (B) dorsal column system

(C) spinocerebellar tracts (D) spinoreticular pathway (E) spinothalamic tracts 33. The drug metformin is an effective treatment for the hyperglycemia associated with diabetes. One of the major sites of action for metformin is the liver and its use is ideal for obese patients and for younger Type II diabetics with normal liver function. Given that the drug lowers circulating levels of glucose, which of the following hepatic enzymes is most likely activated as a consequence of metformin administration? (A) (B) (C) (D)

AMP-activated protein kinase (AMPK) glycogen phosphorylase 6-phosphofructo-1-kinase (PFK-1) phosphoenolpyruvate carboxykinase (PEPCK) (E) cAMP-dependent protein kinase (PKA)

34. A baby boy is delivered without complications at 31 weeks gestational age. However, soon after birth, he develops progressive respiratory distress, hypoxemia, and cyanosis, and requires artificial ventilation and oxygen. Which of the following prenatal laboratory tests could have best predicted these developments? (A) alpha-fetoprotein levels in the mother’s blood (B) chromosomal analysis of the fetal amniotic cells (C) cytomegalovirus antibody levels in the mother’s blood (D) lecithin:sphingomyelin ratio in the amniotic fluid (E) toxicology screen of the mother’s urine 35. Which of the following antiretroviral drugs is most likely to cause pancreatitis? (A) (B) (C) (D) (E)

atazanavir didanosine efavirenz lamivudine tenofovir

Questions: 30–39

(A) (B) (C) (D) (E)

acute suppurative sialoadenitis adenoid cystic carcinoma mucoepidermoid carcinoma pleomorphic adenoma Warthin tumor (adenolymphoma)

37. Aspirin, which has antipyretic activity, has been widely used to lower body temperature in fever. In which of the following situations would aspirin most likely be employed? (A) A 5-year-old boy becomes irritable. He complains of a sore throat and his body temperature is 105ºF. (B) A 20-year-old college student has collapsed after a 10K run in mid-August. His skin is dry and his core body temperature is 104ºF. (C) A 35-year-old woman is placed under general anesthesia for an elective surgical procedure. During the procedure she begins to exhibit muscle rigidity, her blood CO2 levels dramatically increase, and her body temperature rapidly increases to 104ºF. (D) A 60-year-old woman begins to experience flu-like symptoms. Her body temperature is 101ºF. (E) An 80-year-old man is found unresponsive in his apartment. The apartment has no air conditioning and the daily ambient temperature has been over 95ºF for the past week. The patient’s body temperature is 102ºF.

38. Figure 12-3 shows equilibration of three different gases across the pulmonary capillary membrane. Pressures are shown in capillary blood, relative to the alveolar gas pressure. Alveolar pressures are equal to 10 mm Hg for gas A, 1 mm Hg for gas B, and 1 mm Hg for gas C. What is the pressure of gas A in arterial blood?

Pressure in pulmonary capillary (%/alveolar value)

36. A 54-year-old male smoker notices a slowly enlarging mass over the past 2 years within his right parotid gland. At the time of surgical excision, the mass measures 2.8 cm in diameter and is focally cystic. Microscopic examination reveals a tumor composed of benign papillary oncocytic epithelial fronds supported by benign lymphoid stroma. Which of the following is the most likely diagnosis?

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A

100

B

50 C 0

0.4 0.8 Time in capillary (seconds) FIG. 12-3

(A) (B) (C) (D) (E)

0 mm Hg. 1 mm Hg. 10 mm Hg. 100 mm Hg. It can’t be determined based on the available information.

39. A 9-year-old boy developed acute glomerulonephritis following a bacterial skin infection. This illness is most likely due to which of the following? (A) (B) (C) (D)

antigenic mimicry arthus reaction delayed hypersensitivity immediate hypersensitivity induced by penicillin (E) immune complexes

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40. A 2-day-old boy delivered by normal labor (with no known prenatal risk factors) had become lethargic and required stimulation for feeding. When vomiting and hyperventilation ensued, routine laboratory results showed blood urea nitrogen (BUN)