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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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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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
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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: