AAMC MCAT Outline PDF

® What’s on the MCAT Exam? students-residents.aamc.org/mcatexam MCAT® is a program of the Association of American Medical Colleges www.aamc.org/mcat  Contents Introduction...............................................

® What’s on the MCAT Exam? students-residents.aamc.org/mcatexam MCAT® is a program of the Association of American Medical Colleges www.aamc.org/mcat  Contents Introduction.................................................................................................................................................. 2 Scientific Inquiry and Reasoning Skills.......................................................................................................... 4 Biological and Biochemical Foundations of Living Systems........................................................................ 17 Chemical and Physical Foundations of Biological Systems......................................................................... 50 Psychological, Social, and Biological Foundations of Behavior................................................................... 75 Critical Analysis and Reasoning Skills........................................................................................................ 101 © 2020 Association of American Medical Colleges 1  Introduction This document draws from the online resource What’s on the MCAT® Exam? at students- residents.aamc.org/mcatexam. It contains a complete description of the competencies you are responsible for knowing on the MCAT exam. It describes the exam’s content and format. It also lists and discusses the exam’s conceptual framework, organized around foundational concepts, content categories, and scientific inquiry and reasoning skills. Also included are sample test questions that demonstrate how the competencies are tested on the exam. While the content is written for you, the prospective MCAT examinee, the information it provides is likely to be useful to prehealth advisors, other baccalaureate faculty, medical school admissions officers, and medical schools. How Is the MCAT Exam Structured? The MCAT exam has four test sections: ▪ Biological and Biochemical Foundations of Living Systems ▪ Chemical and Physical Foundations of Biological Systems ▪ Psychological, Social, and Biological Foundations of Behavior ▪ Critical Analysis and Reasoning Skills The first three sections are organized around foundational concepts, or “big ideas,” in the sciences. They reflect current research about the most effective ways for students to learn and use science, emphasizing deep knowledge of the most important scientific concepts over knowledge simply of many discrete scientific facts. Leaders in science education say some of the most important foundational concepts in the sciences ask students to integrate and analyze information from different disciplines. In that vein, questions in these sections will ask you to combine your scientific knowledge from multiple disciplines with your scientific inquiry and reasoning skills. You will be asked to demonstrate four different scientific inquiry and reasoning skills on the exam: ▪ Knowledge of scientific concepts and principles. ▪ Scientific reasoning and problem-solving. ▪ Reasoning about the design and execution of research. ▪ Data-based and statistical reasoning. The fourth section of the MCAT exam, Critical Analysis and Reasoning Skills, will be similar to many of the verbal reasoning tests you have taken in your academic career. It includes passages and questions that test your ability to comprehend and analyze what you read. The Critical Analysis and Reasoning Skills section asks you to read and think about passages from a wide range of disciplines in the social sciences and humanities, including those in population health, ethics and philosophy, and studies of diverse cultures. Passages are followed by a series of questions that lead you through the process of © 2020 Association of American Medical Colleges 2  comprehending, analyzing, and reasoning about the material you have read. This section is unique because it has been developed specifically to measure the analytical and reasoning skills you will need to be successful in medical school. © 2020 Association of American Medical Colleges 3  Scientific Inquiry and Reasoning Skills Leaders in medical education believe tomorrow’s physicians need to be able to combine scientific knowledge with skills in scientific inquiry and reasoning. With that in mind, the MCAT exam will ask you to demonstrate four scientific inquiry and reasoning skills that natural, behavioral, and social scientists rely on to advance their work: Knowledge of Scientific Concepts and Principles Demonstrating understanding of scientific concepts and principles. Identifying the relationships between closely related concepts. Scientific Reasoning and Problem-Solving Reasoning about scientific principles, theories, and models. Analyzing and evaluating scientific explanations and predictions. Reasoning About the Design and Execution of Research Demonstrating understanding of important components of scientific research. Reasoning about ethical issues in research. Data-Based and Statistical Reasoning Interpreting patterns in data presented in tables, figures, and graphs. Reasoning about data and drawing conclusions from them. The discussion that follows describes each of the skills and how you may be asked to demonstrate them. Three sample test questions are provided to illustrate each skill: one from the Psychological, Social, and Biological Foundations of Behavior section; one from the Biological and Biochemical Foundations of Living Systems section; and one from the Chemical and Physical Foundations of Biological Systems section. Also included are explanations of how each question tests a specific scientific inquiry and reasoning skill. © 2020 Association of American Medical Colleges 4  Skill 1: Knowledge of Scientific Concepts and Principles The questions in this skill category will ask you to demonstrate your knowledge of the 10 foundational concepts described in subsequent chapters. These questions will ask you to recognize, identify, recall, or define basic concepts in the natural, behavioral, and social sciences as well as their relationships with one another. The concepts and scientific principles may be represented by words, graphs, tables, diagrams, or formulas. As you work on these questions, you may be asked to identify a scientific fact or define a concept. Or you may be asked to apply a scientific principle to a problem. Questions may ask you to identify the relationships between closely related concepts or relate written statements, principles, or concepts to graphic representations of science content. They may ask you to identify examples of natural or data- driven observations that illustrate scientific principles. Questions may ask you to recognize a scientific concept shown in a diagram or represented in a graph. Or they may give you a mathematical equation and ask you to use it to solve a problem. For example, questions that test this skill will ask you to show you understand scientific concepts and principles by: ▪ Recognizing scientific principles from an example, situation, or study. Identifying the relationships among closely related concepts. ▪ Identifying the relationships between different representations of concepts (e.g., written, symbolic, graphic). ▪ Identifying examples of observations that illustrate scientific principles. ▪ Using given mathematical equations to solve problems. ▪ Identifying the simple or familiar molecule that is an example of a specific amino acid. By way of example, questions from the Psychological, Social, and Biological Foundations of Behavior section may ask you to demonstrate your knowledge of scientific concepts and principles by: ▪ Recognizing the principle of retroactive interference. ▪ Using Weber’s law to identify physical differences that are detectable. ▪ Identifying the behavioral change (extinction) that will occur when a learned response is no longer followed by a reinforcer. ▪ Identifying the conceptual similarities or differences between operant conditioning and classical conditioning. ▪ Identifying a graph that illustrates the relationship between educational attainment and life expectancy. ▪ Recognizing conditions that result in learned helplessness. ▪ Concluding which stage of cognitive development a child is in, according to Piaget’s theory, when presented with a description of how a child responds to a conservation problem. © 2020 Association of American Medical Colleges 5  The three sample questions that follow illustrate Skill 1 questions from, respectively, the Psychological, Social, and Biological Foundations of Behavior section; the Biological and Biochemical Foundations of Living Systems section; and the Chemical and Physical Foundations of Biological System section of the MCAT exam. Skill 1 Example From the Psychological, Social, and Biological Foundations of Behavior Section In a study, each trial involves administering a drop of lemon juice to the participant’s tongue and measuring the participant’s level of salivation. As more trials are conducted, the researcher finds that the magnitude of salivation declines. After a certain point, the researcher switches to administering lime juice. This researcher is most likely studying which process? A. Sensory perception B. Habituation and dishabituation C. Stimulus generalization in classical conditioning D. Conditioned responses in classical conditioning The correct answer is B. This Skill 1 question tests your knowledge of the scientific concepts and principles described by Content Category 7C, Attitude and behavior change (see page 90), and is a Skill 1 question because it requires you to relate scientific concepts. This question asks you to identify the process involved in the study that connects reduced responding to a repeated stimulus and then a change in the stimulus, which is habituation and dishabituation, allowing for the conclusion that B is the correct answer. Skill 1 Example From the Chemical and Physical Foundations of Biological Systems Section What type of functional group is formed when aspartic acid reacts with another amino acid to form a peptide bond? A. An amine group B. An aldehyde group C. An amide group D. A carboxyl group The correct answer is C. This is a Skill 1 question and relates to Content Category 5D, Structure, function, and reactivity of biologically relevant molecules. It is a Skill 1 question because you must recognize the structural relationship between free amino acids and peptides. To answer the question, you must know that the functional group that forms during peptide bond formation is an amide group. Skill 2: Scientific Reasoning and Problem-Solving Questions that test scientific reasoning and problem-solving skills differ from questions in the previous category by asking you to use your scientific knowledge to solve problems in the natural, behavioral, and social sciences. © 2020 Association of American Medical Colleges 6  As you work on questions that test this skill, you may be asked to use scientific theories to explain observations or make predictions about natural or social phenomena. Questions may ask you to judge the credibility of scientific explanations or to evaluate arguments about cause and effect. Or they may ask you to use scientific models and observations to draw conclusions. They may ask you to identify scientific findings that call a theory or model into question. Questions in this category may ask you to look at pictures or diagrams and draw conclusions from them. Or they may ask you to determine and then use scientific formulas to solve problems. For example, you will be asked to show you can use scientific principles to solve problems by: ▪ Reasoning about scientific principles, theories, and models to make predictions or determine consequences. ▪ Analyzing and evaluating the validity or credibility of scientific explanations and predictions. ▪ Evaluating arguments about causes and consequences to determine the most valid argument when using scientific knowledge. ▪ Bringing together theory, observations, and evidence to draw conclusions. ▪ Recognizing or identifying scientific findings from a given study that challenge or invalidate a scientific theory or model. ▪ Determining and using scientific formulas to solve problems. ▪ Identifying the bond that would form between two structures if they were adjacent to each other. By way of illustration, questions from the Psychological, Social, and Biological Foundations of Behavior section may ask you demonstrate this skill by: ▪ Using the main premises of symbolic interactionism, use reasoning in an observational study of physician-patient interactions to describe how the premises are connected to perceived patient compliance. ▪ Predicting how an individual will react to cognitive dissonance. ▪ Using reasoning to determine whether a causal explanation is possible when given an example of how someone’s gender or personality predicts his or her behavior. ▪ Explaining how an example, such as when an anorexic teenager restricts eating to satisfy esteem needs, is compatible with the premises of Maslow’s hierarchy of needs. ▪ Drawing a conclusion about which sociological theory would be most consistent with a conceptual diagram that explains how social and environmental factors influence health and why this theory is most consistent. ▪ Identifying the relationship between social institutions that is suggested by an illustration used in a public health campaign. ▪ Recognizing a demographic trend that is represented in a population pyramid. © 2020 Association of American Medical Colleges 7  For more context, let’s consider three Skill 2 questions linked to different foundational concepts in the Psychological, Social, and Biological Foundations of Behavior section; the Biological and Biochemical Foundations of Living Systems section; and the Chemical and Physical Foundations of Biological Systems section. Skill 2 Example From the Psychological, Social, and Biological Foundations of Behavior Section Which statement describes what the concept of cultural capital predicts? A. Cultural distinctions associated with the young will be more valued within a society. B. With improved communication, there will eventually be a convergence of cultural practices of all classes. C. Cultural distinctions by class will become less important during a recession because people will have less money to spend. D. Cultural distinctions associated with elite classes will be more valued within a society. The correct answer is D. It is a Skill 2 question and assesses knowledge of Content Category 10A, Social inequality. It is a Skill 2 question because it requires you to make a prediction based on a particular concept. This question requires you to understand the concept of cultural capital in order to evaluate which prediction about social stratification would be most consistent with the concept. Skill 2 Example From the Biological and Biochemical Foundations of Living Systems Section Starting with the translation initiation codon, how many amino acids for this polypeptide does the sequence shown encode? 5'-CUGCCAAUGUGCUAAUCGCGGGGG-3' A. 2 B. 3 C. 6 D. 8 The correct answer is A. This is a Skill 2 question, and you must use knowledge from Content Category 1B, Transmission of genetic information from the gene to the protein, to solve this problem. In addition to recalling the sequence for the start codon, this is a Skill 2 question because it requires you to apply the scientific principle of the genetic code to the provided RNA sequence. As a Skill 2 question, reasoning about the role of the stop codon in translation will allow you to arrive at the conclusion that this sequence codes for a polypeptide with two amino acids. © 2020 Association of American Medical Colleges 8  Skill 2 Example From the Chemical and Physical Foundations of Biological Systems Section The radius of the aorta is about 1.0 cm, and blood passes through it at a velocity of 30 cm/s. A typical capillary has a radius of about 4 × 10–4 cm, with blood passing through at a velocity of 5 × 10–2 cm/s. Using these data, what is the approximate number of capillaries in a human body? A. 1 × 104 B. 2 × 107 C. 4 × 109 D. 7 × 1012 The correct answer is C. This Skill 2 question relates to Content Category 4B, Importance of fluids for the circulation of blood, gas movement, and gas exchange. This question asks you to use a mathematical model to make predictions about natural phenomena. To answer this question, you must be able to recognize the principles of flow characteristics of blood in the human body and apply the appropriate mathematical model to an unfamiliar scenario. Answering this question first requires recognition that the volume of blood flowing through the aorta is the same volume of blood flowing through the capillaries. It is a Skill 2 question because you then need to use reasoning skills to find the difference in the volumes that the aorta and capillaries can each carry in order to calculate the total number of capillaries. Skill 3: Reasoning About the Design and Execution of Research Questions that test reasoning about the design and execution of research will ask you to demonstrate your scientific inquiry skills by showing you can “do” science. They will ask you to demonstrate your understanding of important components of scientific methodology. These questions will ask you to demonstrate your knowledge of the ways natural, behavioral, and social scientists conduct research to test and extend scientific knowledge. As you work on these questions, you may be asked to show how scientists use theory, past research findings, and observations to ask testable questions and pose hypotheses. Questions that test this skill may ask you to use reasoning to identify the best way for scientists to gather data from samples of members of the population they would like to draw inferences about. They may ask you to identify how scientists manipulate and control variables to test their hypotheses or to identify and determine different ways scientists take measurements and record results. The questions may ask you to identify faulty research logic or point out the limitations of the research studies that are described. Or they may ask you to identify factors that might confuse or confound the inferences you can draw from the results. These questions may also ask you to demonstrate and use your understanding of the ways scientists adhere to ethical guidelines to protect the rights, safety, and privacy of research participants, the integrity of the scientists’ work, and the interests of research consumers. © 2020 Association of American Medical Colleges 9  For example, questions that test this skill will ask you to use your knowledge of important components of scientific methodology by: ▪ Identifying the role of theory, past findings, and observations in scientific questioning. ▪ Identifying testable research questions and hypotheses. ▪ Distinguishing between samples and populations and between results that support and fail to support generalizations about populations. ▪ Identifying the relationships among the variables in a study (e.g., independent versus dependent variables; control and confounding variables). ▪ Using reasoning to evaluate the appropriateness, precision, and accuracy of tools used to conduct research in the natural sciences. ▪ Using reasoning to evaluate or determine the appropriateness, reliability, and validity of tools used to conduct research in the behavioral and social sciences. ▪ Using reasoning to determine which features of research studies suggest associations between variables or causal relationships between them (e.g., temporality, random assignment). ▪ Using reasoning to evaluate ethical issues when given information about a study. ▪ Determining which molecule is a product of two other molecules without rearrangement. For example, questions from the Psychological, Social, and Biological Foundations of Behavior section may ask you to reason about the design and execution of research by: ▪ Identifying the basic components of survey methods, ethnographic methods, experimental methods, or other types of research designs in psychology and sociology. ▪ Selecting a hypothesis about semantic activation. ▪ Identifying the extent to which a finding can be generalized to the population when given details about how participants were recruited for an experiment in language development. ▪ Identifying the experimental setup in which researchers manipulate self-confidence. ▪ Identifying the most appropriate way to assess prejudice in a study on implicit bias. ▪ Using reasoning to determine or evaluate the implications of relying on self-report measures for a specific study. ▪ Identifying the third variable that may be confounding the findings from a correlational study. ▪ Making judgments about the reliability and validity of specific measures when given information about the response patterns of participants. ▪ Identifying whether researchers violated any ethical codes when given information about a study. The three sample questions that follow illustrate Skill 3 questions from, respectively, the Psychological, Social, and Biological Foundations of Behavior section; the Biological and Biochemical Foundations of Living Systems section; and the Chemical and Physical Foundations of Biological Systems section of the MCAT exam. © 2020 Association of American Medical Colleges 10  Skill 3 Example From the Psychological, Social, and Biological Foundations of Behavior Section Researchers conducted an experiment to test social loafing. They asked participants to prepare an annual report or a tax return. Some participants performed the task individually and others performed it as a group. What are the independent and dependent variables? A. The independent variable is the overall productivity of the group, and the dependent variable is each participant’s contribution to the task. B. The independent variable is the type of task, and the dependent variable is whether the participants worked alone or in a group. C. The independent variable is whether the participant worked alone or in a group, and the dependent variable is each participant’s contribution to the task. D. The independent variable is whether the participant worked alone or in a group, and the dependent variable is the type of the task. The correct answer is C. This Skill 3 question assesses knowledge of Content Category 7B, Social processes that influence human behavior. This question is a Skill 3 question because it requires you to use reasoning skills in research design. This question requires you to understand social loafing and draw inferences about the dependent and independent variables based on this concept and the description of the experimental design. Skill 3 Example from the Biological and Biochemical Foundations of Living Systems Section Sodium dodecyl sulfate (SDS) contains a 12-carbon tail attached to a sulfate group and is used in denaturing gel electrophoresis of proteins. Numerous SDS molecules will bind to the exposed hydrophobic regions of denatured proteins. How does the use of SDS in this experiment allow for the separation of proteins? A. by charge B. by molecular weight C. by shape D. by solubility The correct answer is B. This is a Skill 3 question and requires knowledge from Content Category 1A, Structure and function of proteins and their constituent amino acids. It is a Skill 3 question because it requires you to understand the design of a denaturing gel electrophoresis experiment and the role that SDS plays in this technique. Based on this understanding, you will be able to determine that proteins will be separated only by molecular weight. © 2020 Association of American Medical Colleges 11  Skill 3 Example From the Chemical and Physical Foundations of Biological Systems Section A test for proteins in urine involves precipitation but is often complicated by precipitation of calcium phosphate. Which procedure prevents precipitation of the salt? A. addition of buffer to maintain high pH B. addition of buffer to maintain neutral pH C. addition of calcium hydroxide D. addition of sodium phosphate The correct answer is B. This is a Skill 3 question and relates to Content Category 5B, Nature of molecules and intermolecular interactions. In this Skill 3 question, you must identify a change in an experimental approach that would eliminate a frequently encountered complication. The complication in this case is related to the test for protein-involving precipitation. The test will give a false positive if calcium phosphate precipitates. To answer this Skill 3 question, you need to use reasoning skills to determine how changing experimental parameters will eliminate the complication. Skill 4: Data-Based and Statistical Reasoning Like questions about Skill 3, questions that test Skill 4 will ask you to show you can “do” science, this time by demonstrating your data-based and statistical reasoning skills. Questions that test this skill will ask you to reason with data. They will ask you to read and interpret results using tables, graphs, and charts. These questions will ask you to demonstrate you can identify patterns in data and draw conclusions from evidence. Questions that test this skill may ask you to demonstrate your knowledge of the ways natural, behavioral, and social scientists use measures of central tendency and dispersion to describe their data. These questions may ask you to demonstrate your understanding of the ways scientists think about random and systematic errors in their experiments and datasets. They may also ask you to demonstrate your understanding of how scientists think about uncertainty and the implications of uncertainty for statistical testing and the inferences they can draw from their data. These questions may ask you to show how scientists use data to make comparisons between variables or explain relationships between them or make predictions. They may ask you to use data to answer research questions or draw conclusions. These questions may ask you to demonstrate your knowledge of the ways scientists draw inferences from their results about associations between variables or causal relationships between them. Questions that test this skill may ask you to examine evidence from a scientific study and point out statements that go beyond the evidence. Or they may ask you to suggest alternative explanations for the same data. © 2020 Association of American Medical Colleges 12  For example, questions that test this skill will ask you to use your knowledge of data-based and statistical reasoning by: ▪ Using, analyzing, and interpreting data in figures, graphs, and tables to draw a conclusion about expected results if the experiment was to be completed again. ▪ Evaluating whether representations are an appropriate or reliable fit for particular scientific observations and data. ▪ Using measures of central tendency (mean, median, and mode) and measures of dispersion (range, inter-quartile range, and standard deviation) to describe data. ▪ Using reasoning about random and systematic error. ▪ Using reasoning about statistical significance and uncertainty (e.g., interpreting statistical significance levels, interpreting a confidence interval) and relating this information to conclusions that can or cannot be made about the study. ▪ Using data to explain relationships between variables. ▪ Using data to answer research questions and draw conclusions. ▪ Identifying conclusions supported by research results. ▪ Determining the implications of results for real-world situations. ▪ Using structural comparisons to make predictions about chemical properties in an unfamiliar scenario. For example, questions from the Psychological, Social, and Biological Foundations of Behavior section may ask you to demonstrate your use of data-based and statistical reasoning by: ▪ Identifying the correlation between a demographic variable, such as race/ethnicity, gender, or age, and life expectancy or another health outcome. ▪ Identifying the relationship between demographic variables and health variables reported in a table or figure. ▪ Explaining why income data are usually reported using the median rather than the mean. ▪ Using reasoning to identify or evaluate what inference is supported by a table of correlations between different socioeconomic variables and level of participation in different physical activities. ▪ Using reasoning about the type of comparisons made in an experimental study of cognitive dissonance and evaluating what the findings imply for attitude and behavior change. ▪ Drawing conclusions about the type of memory affected by an experimental manipulation when you are shown a graph of findings from a memory experiment. ▪ Distinguishing the kinds of claims that can be made when using longitudinal data, cross-sectional data, or experimental data in studies of social interaction. ▪ Identifying which conclusion about mathematical understanding in young children is supported by time data reported in a developmental study. ▪ Evaluating data collected from different types of research studies, such as comparing results from a qualitative study of mechanisms for coping with stress with results from a quantitative study of social support networks. © 2020 Association of American Medical Colleges 13  ▪ Using data, such as interviews with cancer patients or a national survey of health behaviors, to determine a practical application based on a study’s results. The three questions that follow illustrate Skill 4 questions from, respectively, the Psychological, Social, and Biological Foundations of Behavior section; the Biological and Biochemical Foundations of Living Systems section; and the Chemical and Physical Foundations of Biological Systems section of the MCAT exam. Skill 4 Example From the Psychological, Social, and Biological Foundations of Behavior Section Which correlation supports the bystander effect? A. The number of bystanders is positively correlated with the time it takes for someone to offer help in the case of an emergency. B. The number of bystanders is negatively correlated with the time it takes for someone to offer help in the case of an emergency. C. The number of bystanders is positively correlated with whether people judge a situation to be an emergency. D. The number of bystanders is negatively correlated with whether people judge a situation to be an emergency. The correct answer is A. This Skill 4 question assesses knowledge of Content Category 7B, Social processes that influence human behavior. It is a Skill 4 question because it requires you to engage in statistical reasoning. This question requires you to understand the distinction between negative and positive correlations and make a prediction about data based on your knowledge of the bystander effect. © 2020 Association of American Medical Colleges 14  Skill 4 Example From the Biological and Biochemical Foundations of Living Systems Section In the figure, the three curves represent hemoglobin oxygen binding at three different pH values, pH 7.2, pH 7.4, and pH 7.6. What conclusion can be drawn from these data about the oxygen binding of hemoglobin at different pH values? A. Low pH favors the high-affinity oxygen-binding state. B. Low pH favors the low-affinity oxygen-binding state. C. Oxygen affinity is independent of pH. D. Oxygen binding is noncooperative at low pH. The correct answer is B. This Skill 4 question draws on knowledge from Content Category 1A, Structure and function of proteins and their constituent amino acids. This is a Skill 4 question because it asks you to use data to explain a property of hemoglobin. You must evaluate the hemoglobin oxygen-binding data for each pH value and compare them to determine the relationship between pH and hemoglobin oxygen affinity in order to conclude that low pH favors the low-affinity oxygen-binding state. © 2020 Association of American Medical Colleges 15  Skill 4 Example From the Chemical and Physical Foundations of Biological Systems Section Four different solutions of a single amino acid were titrated, and the pK values of the solute were determined. Solution pK1 pK2 pK3 1 2.10 3.86 9.82 2 2.10 4.07 9.47 3 2.32 9.76 Not Applicable 4 2.18 9.04 12.48 Which solution contains an amino acid that would be most likely to stabilize an anionic substrate in an enzyme pocket at physiological pH? A. Solution 1 B. Solution 2 C. Solution 3 D. Solution 4 The correct answer is D. This Skill 4 question includes a table and assesses knowledge of Content Category 5D, Structure, function, and reactivity of biologically relevant molecules. Here you see that four different solutions of a single amino acid were titrated, and the pK values were determined. These values are found in the table. This is a Skill 4 question because you must recognize a data pattern in the table, make comparisons, and use those comparisons to make a prediction. Using knowledge of amino acids and peptide bonds and the patterns you see in the data, you can determine that the N- and C- terminus pK values, roughly 2 and 9 for all solutions, can be ignored since these groups will be involved in peptide bond formation. With further analyses, you can determine that only Solution 4 will be cationic at physiological pH. © 2020 Association of American Medical Colleges 16  Biological and Biochemical Foundations of Living Systems What Will the Biological and Biochemical Foundations of Living Systems Section Test? The Biological and Biochemical Foundations of Living Systems section asks you to solve problems by combining your knowledge of biological and biochemical concepts with your scientific inquiry and reasoning skills. This section tests processes that are unique to living organisms, such as growing and reproducing, maintaining a constant internal environment, acquiring materials and energy, sensing and responding to environmental changes, and adapting. It also tests how cells and organ systems within an organism act independently and in concert to accomplish these processes, and it asks you to reason about these processes at various levels of biological organization within a living system. This section is designed to: ▪ Test introductory-level biology, organic chemistry, and inorganic chemistry concepts. ▪ Test biochemistry concepts at the level taught in many colleges and universities in first-semester biochemistry courses. ▪ Test cellular and molecular biology topics at the level taught in many colleges and universities in introductory biology sequences and first-semester biochemistry courses. ▪ Test basic research methods and statistics concepts described by many baccalaureate faculty as important to success in introductory science courses. ▪ Require you to demonstrate your scientific inquiry and reasoning, research methods, and statistics skills as applied to the natural sciences. Test Section Number of Questions Time Biological and Biochemical 59 95 minutes Foundations of Living Systems (note that questions are a combination of passage-based and discrete questions) © 2020 Association of American Medical Colleges 17  Scientific Inquiry and Reasoning Skills As a reminder, the scientific inquiry and reasoning skills you will be asked to demonstrate on this section of the exam are: Knowledge of Scientific Concepts and Principles ▪ Demonstrating understanding of scientific concepts and principles. ▪ Identifying the relationships between closely related concepts. Scientific Reasoning and Problem-Solving ▪ Reasoning about scientific principles, theories, and models. ▪ Analyzing and evaluating scientific explanations and predictions. Reasoning About the Design and Execution of Research ▪ Demonstrating understanding of important components of scientific research. ▪ Reasoning about ethical issues in research. Data-Based and Statistical Reasoning ▪ Interpreting patterns in data presented in tables, figures, and graphs. ▪ Reasoning about data and drawing conclusions from them. © 2020 Association of American Medical Colleges 18  General Mathematical Concepts and Techniques It’s important for you to know that questions on the natural, behavioral, and social sciences sections will ask you to use certain mathematical concepts and techniques. As the descriptions of the scientific inquiry and reasoning skills suggest, some questions will ask you to analyze and manipulate scientific data to show you can: ▪ Recognize and interpret linear, semilog, and log-log scales and calculate slopes from data found in figures, graphs, and tables. ▪ Demonstrate a general understanding of significant digits and the use of reasonable numerical estimates in performing measurements and calculations. ▪ Use metric units, including converting units within the metric system and between metric and English units (conversion factors will be provided when needed), and dimensional analysis (using units to balance equations). ▪ Perform arithmetic calculations involving the following: probability, proportion, ratio, percentage, and square-root estimations. ▪ Demonstrate a general understanding (Algebra II-level) of exponentials and logarithms (natural and base 10), scientific notation, and solving simultaneous equations. ▪ Demonstrate a general understanding of the following trigonometric concepts: definitions of basic (sine, cosine, tangent) and inverse (sin‒1, cos‒1, tan‒1) functions; sin and cos values of 0°, 90°, and 180°; relationships between the lengths of sides of right triangles containing angles of 30°, 45°, and 60°. ▪ Demonstrate a general understanding of vector addition and subtraction and the right-hand rule (knowledge of dot and cross products is not required). Note also that an understanding of calculus is not required, and a periodic table will be provided during the exam. © 2020 Association of American Medical Colleges 19  Resource You will have access to the periodic table shown while answering questions in this section of the exam. © 2020 Association of American Medical Colleges 20  Biological and Biochemical Foundations of Living Systems Distribution of Questions by Discipline, Foundational Concept, and Scientific Inquiry and Reasoning Skill You may wonder how much biochemistry you’ll see on this section of the MCAT exam, how many questions you’ll get about a particular foundational concept, or how the scientific inquiry and reasoning skills will be distributed on your exam. The questions you see are likely to be distributed in the ways described below. These are the approximate percentages of questions you’ll see for each discipline, foundational concept, and scientific inquiry and reasoning skill. (These percentages have been approximated to the nearest 5% and will vary from one test to another for a variety of reasons, including, but not limited to, controlling for question difficulty, using groups of questions that depend on a single passage, and using unscored field-test questions on each test form.) Discipline: ▪ First-semester biochemistry, 25% ▪ Introductory biology, 65% ▪ General chemistry, 5% ▪ Organic chemistry, 5% Foundational Concept: ▪ Foundational Concept 1, 55% ▪ Foundational Concept 2, 20% ▪ Foundational Concept 3, 25% Scientific Inquiry and Reasoning Skill: ▪ Skill 1, 35% ▪ Skill 2, 45% ▪ Skill 3, 10% ▪ Skill 4, 10% © 2020 Association of American Medical Colleges 21  Biological and Biochemical Foundations of Living Systems Framework of Foundational Concepts and Content Categories Foundational Concept 1: Biomolecules have unique properties that determine how they contribute to the structure and function of cells and how they participate in the processes necessary to maintain life. The content categories for this foundational concept include: 1A. Structure and function of proteins and their constituent amino acids. 1B. Transmission of genetic information from the gene to the protein. 1C. Transmission of heritable information from generation to generation and the processes that increase genetic diversity. 1D. Principles of bioenergetics and fuel molecule metabolism. Foundational Concept 2: Highly organized assemblies of molecules, cells, and organs interact to carry out the functions of living organisms. The content categories for this foundational concept include: 2A. Assemblies of molecules, cells, and groups of cells within single cellular and multicellular organisms. 2B. The structure, growth, physiology, and genetics of prokaryotes and viruses. 2C. Processes of cell division, differentiation, and specialization. Foundational Concept 3: Complex systems of tissues and organs sense the internal and external environments of multicellular organisms, and through integrated functioning, maintain a stable internal environment within an ever-changing external environment. The content categories for this foundational concept include: 3A. Structure and functions of the nervous and endocrine systems and ways these systems coordinate the organ systems. 3B. Structure and integrative functions of the main organ systems. © 2020 Association of American Medical Colleges 22  How Foundational Concepts and Content Categories Fit Together The MCAT exam asks you to solve problems by combining your knowledge of concepts with your scientific inquiry and reasoning skills. The figure below illustrates how foundational concepts, content categories, and scientific inquiry and reasoning skills intersect when test questions are written. Foundational Concept 1 Foundational Concept 2 Content Content Content Content Content Content Category 1A Category 1B Category 1C Category 2A Category 2B Category 2C Skill Skill 1 ▪ Each cell represents the point at which foundational Skill 2 concepts, content categories, and scientific inquiry and reasoning skills cross. Skill 3 ▪ Test questions are written at the intersections of the Skill 4 knowledge and skills. © 2020 Association of American Medical Colleges 23  Understanding the Foundational Concepts and Content Categories in the Biological and Biochemical Foundations of Living Systems Section The following are detailed explanations of each foundational concept and related content categories tested in the Biological and Biochemical Foundations of Living Systems section. To help you prepare for the MCAT exam, we provide content lists that describe specific topics and subtopics that define each content category for this section. The same content lists are provided to the writers who develop the content of the exam. Here is an excerpt from the content list. EXCERPT FROM BIOLOGICAL AND BIOCHEMICAL FOUNDATONS OF LIVING SYSTEMS OUTLINE Metabolism of Fatty Acids and Proteins (BIO, BC) Topic ▪ Description of fatty acids (BC) Subtopic ▪ Digestion, mobilization, and transport of fats ▪ Oxidation of fatty acids o Saturated fats o Unsaturated fats ▪ Ketone bodies (BC) ▪ Anabolism of fats (BIO) ▪ Nontemplate synthesis: biosynthesis of lipids and polysaccharides (BIO) ▪ Metabolism of proteins (BIO) The abbreviations in parentheses indicate the courses in which undergraduate students at many colleges and universities learn about the topics and associated subtopics. The course abbreviations are: ▪ BC: first-semester biochemistry ▪ BIO: two-semester sequence of introductory biology ▪ GC: two-semester sequence of general chemistry ▪ OC: two-semester sequence of organic chemistry In preparing for the MCAT exam, you will be responsible for learning the topics and associated subtopics at the levels taught at many colleges and universities in the courses listed in parentheses. A small number of subtopics have course abbreviations indicated in parentheses. In those cases, you are responsible only for learning the subtopics as they are taught in the course(s) indicated. Using the excerpt above as an example: ▪ You are responsible for learning about the topic Metabolism of Fatty Acids and Proteins at the level taught in a typical two-semester introductory biology sequence and in a typical first- semester biochemistry course. © 2020 Association of American Medical Colleges 24  ▪ You are responsible for learning about the subtopics Anabolism of fats, Nontemplate synthesis: biosynthesis of lipids and polysaccharides, and Metabolism of proteins only at the levels taught in a typical two-semester sequence of introductory biology. ▪ You are responsible for learning about the subtopics Description of fatty acids and Ketone bodies only at the levels taught in a typical first-semester biochemistry course. Remember that course content at your school may differ from course content at other colleges and universities. The topics and subtopics described in this and the next two chapters may be covered in courses with titles that are different from those listed here. Your prehealth advisor and faculty are important resources for your questions about course content. Please Note Topics that appear on multiple content lists will be treated differently. Questions will focus on the topics as they are described in the narrative for the content category. © 2020 Association of American Medical Colleges 25  Biological and Biochemical Foundations of Living Systems Foundational Concept 1 Biomolecules have unique properties that determine how they contribute to the structure and function of cells and how they participate in the processes necessary to maintain life. The unique chemical and structural properties of biomolecules determine the roles they play in cells. The proper functioning of a living system depends on the many components acting harmoniously in response to a constantly changing environment. Biomolecules are constantly formed or degraded in response to the perceived needs of the organism. Content Categories ▪ Category 1A focuses on the structural and functional complexity of proteins, which is derived from their component amino acids, the sequence in which the amino acids are covalently bonded, and the three-dimensional structures the proteins adopt in an aqueous environment. ▪ Category 1B focuses on the molecular mechanisms responsible for the transfer of sequence-specific biological information between biopolymers that ultimately result in the synthesis of proteins. ▪ Category 1C focuses on the mechanisms that function to transmit the heritable information stored in DNA from generation to generation. ▪ Category 1D focuses on the biomolecules and regulated pathways involved in harvesting chemical energy stored in fuel molecules, which serves as the driving force for all the processes that take place within a living system. With these building blocks, medical students will be able to learn how the major biochemical, genetic, and molecular functions of the cell support health and lead disease. 1A: Structure and function of proteins and their Amino Acids (BC, OC) constituent amino acids ▪ Description Macromolecules formed from amino acids adopt well- o Absolute configuration at the α position defined, three-dimensional structures with chemical o Amino acids as dipolar ions properties that are responsible for their participation in o Classifications virtually every process occurring within and between ▪ Acidic or basic cells. The three-dimensional structure of proteins is a ▪ Hydrophobic or hydrophilic direct consequence of the nature of the covalently ▪ Reactions bonded sequence of amino acids, their chemical and o Sulfur linkage for cysteine and cystine physical properties, and the way the whole assembly o Peptide linkage: polypeptides and proteins interacts with water. o Hydrolysis © 2020 Association of American Medical Colleges 26  Enzymes are proteins that interact in highly regio- and Protein Structure (BIO, BC, OC) stereo-specific ways with dissolved solutes. They either ▪ Structure facilitate the chemical transformation of these solutes o 1° structure of proteins or allow for their transport innocuously. Dissolved o 2° structure of proteins solutes compete for protein-binding sites, and protein o 3° structure of proteins; role of proline, cystine, conformational dynamics give rise to mechanisms hydrophobic bonding capable of controlling enzymatic activity. o 4° structure of proteins (BIO, BC) The infinite variability of potential amino acid ▪ Conformational stability sequences allows for adaptable responses to o Denaturing and folding pathogenic organisms and materials. The rigidity of o Hydrophobic interactions some amino acid sequences makes them suitable for o Solvation layer (entropy) (BC) structural roles in complex living systems. ▪ Separation techniques o Isoelectric point Content in this category covers a range of protein o Electrophoresis behaviors that originate from the unique chemistry of amino acids themselves. Amino acid classifications and Nonenzymatic Protein Function (BIO, BC) protein structural elements are covered. Special ▪ Binding (BC) emphasis is placed on enzyme catalysis, including ▪ Immune system mechanistic considerations, kinetics, models of ▪ Motors enzyme-substrate interaction, and regulation. Enzyme Structure and Function (BIO, BC) ▪ Function of enzymes in catalyzing biological reactions ▪ Enzyme classification by reaction type ▪ Reduction of activation energy ▪ Substrates and enzyme specificity ▪ Active Site Model ▪ Induced-Fit Model ▪ Mechanism of catalysis o Cofactors o Coenzymes o Water-soluble vitamins ▪ Effects of local conditions on enzyme activity Control of Enzyme Activity (BIO, BC) ▪ Kinetics o General (catalysis) o Michaelis-Menten o Cooperativity © 2020 Association of American Medical Colleges 27  ▪ Feedback regulation ▪ Inhibition ― types o Competitive o Noncompetitive o Mixed (BC) o Uncompetitive (BC) ▪ Regulatory enzymes o Allosteric enzymes o Covalently modified enzymes o Zymogen 1B: Transmission of genetic information from the gene Nucleic Acid Structure and Function (BIO, BC) to the protein ▪ Description Biomolecules and biomolecular assemblies interact in ▪ Nucleotides and nucleosides specific, highly regulated ways to transfer sequence o Sugar phosphate backbone information between biopolymers in living organisms. o Pyrimidine, purine residues By storing and transferring biological information, DNA ▪ Deoxyribonucleic acid (DNA): double helix, and RNA enable living organisms to reproduce their Watson-Crick model of DNA structure complex components from one generation to the next. ▪ Base pairing specificity: A with T, G with C The nucleotide monomers of these biopolymers, being ▪ Function in transmission of genetic information joined by phosphodiester linkages, form a (BIO) polynucleotide molecule with a “backbone” composed ▪ DNA denaturation, reannealing, hybridization of repeating sugar-phosphate units and “appendages” DNA Replication (BIO) of nitrogenous bases. The unique sequence of bases in each gene provides specific information to the cell. ▪ Mechanism of replication: separation of strands, specific coupling of free nucleic acids DNA molecules are composed of two polynucleotides ▪ Semiconservative nature of replication that spiral around an imaginary axis, forming a double ▪ Specific enzymes involved in replication helix. The two polynucleotides are held together by ▪ Origins of replication, multiple origins in hydrogen bonds between the paired bases and van der eukaryotes Waals interactions between the stacked bases. The ▪ Replicating the ends of DNA molecules pairing between the bases of two polynucleotides is very specific, and its complementarity allows for a Repair of DNA (BIO) precise replication of the DNA molecule. ▪ Repair during replication The DNA inherited by an organism leads to specific ▪ Repair of mutations traits by dictating the synthesis of the biomolecules (RNA molecules and proteins) involved in protein Genetic Code (BIO) synthesis. While every cell in a multicellular organism ▪ Central Dogma: DNA → RNA → protein inherits the same DNA, its expression is precisely ▪ The triplet code © 2020 Association of American Medical Colleges 28  regulated such that different genes are expressed by ▪ Codon-anticodon relationship cells at different stages of development, by cells in ▪ Degenerate code, wobble pairing different tissues, and by cells exposed to different ▪ Missense, nonsense codons stimuli. ▪ Initiation, termination codons ▪ Messenger RNA (mRNA) The topics included in this category concern not only the molecular mechanisms of the transmission of Transcription (BIO) genetic information from the gene to the protein ▪ Transfer RNA (tRNA); ribosomal RNA (rRNA) (transcription and translation), but also the ▪ Mechanism of transcription biosynthesis of the important molecules and molecular ▪ mRNA processing in eukaryotes, introns, exons assemblies involved in these mechanisms. The control ▪ Ribozymes, spliceosomes, small nuclear of gene expression in prokaryotes and eukaryotes is ribonucleoproteins (snRNPs), small nuclear RNAs also included. (snRNAs) Broadly speaking, the field of biotechnology uses ▪ Functional and evolutionary importance of biological systems, living organisms, or derivatives introns thereof to make or modify products or processes for Translation (BIO) specific use. The biotechnological techniques emphasized in this category, however, are those that ▪ Roles of mRNA, tRNA, rRNA take advantage of the complementary structure of ▪ Role and structure of ribosomes double-stranded DNA molecules to synthesize, ▪ Initiation, termination co-factors sequence, and amplify them and to analyze and ▪ Post-translational modification of proteins identify unknown polynucleotide sequences. Included within this treatment of biotechnology are those Eukaryotic Chromosome Organization (BIO) practical applications that directly impact humans, such ▪ Chromosomal proteins as medical applications, human gene therapy, and ▪ Single copy vs. repetitive DNA pharmaceuticals. ▪ Supercoiling Content in this category covers the biopolymers, ▪ Heterochromatin vs. euchromatin including ribonucleic acid (RNA), deoxyribonucleic acid ▪ Telomeres, centromeres (DNA), proteins, and the biochemical processes Control of Gene Expression in Prokaryotes (BIO) involved in carrying out the transfer of biological information from DNA. ▪ Operon Concept, Jacob-Monod Model ▪ Gene repression in bacteria ▪ Positive control in bacteria Control of Gene Expression in Eukaryotes (BIO) ▪ Transcriptional regulation ▪ DNA binding proteins, transcription factors ▪ Gene amplification and duplication ▪ Post-transcriptional control, basic concept of splicing (introns, exons) © 2020 Association of American Medical Colleges 29  ▪ Cancer as a failure of normal cellular controls, oncogenes, tumor suppressor genes ▪ Regulation of chromatin structure ▪ DNA methylation ▪ Role of noncoding RNAs Recombinant DNA and Biotechnology (BIO) ▪ Gene cloning ▪ Restriction enzymes ▪ DNA libraries ▪ Generation of cDNA ▪ Hybridization ▪ Expressing cloned genes ▪ Polymerase chain reaction ▪ Gel electrophoresis and Southern blotting ▪ DNA sequencing ▪ Analyzing gene expression ▪ Determining gene function ▪ Stem cells ▪ Practical applications of DNA technology: medical applications, human gene therapy, pharmaceuticals, forensic evidence, environmental cleanup, agriculture ▪ Safety and ethics of DNA technology 1C: Transmission of heritable information from Evidence That DNA Is Genetic Material (BIO) generation to generation and the processes that Mendelian Concepts (BIO) increase genetic diversity ▪ Phenotype and genotype The information necessary to direct life functions is ▪ Gene contained within discrete nucleotide sequences ▪ Locus transmitted from generation to generation by ▪ Allele: single and multiple mechanisms that, by nature of their various processes, ▪ Homozygosity and heterozygosity provide the raw materials for evolution by increasing ▪ Wild-type genetic diversity. Specific sequences of ▪ Recessiveness deoxyribonucleic acids store and transfer the heritable ▪ Complete dominance information necessary for the continuation of life from ▪ Co-dominance one generation to the next. These sequences, called ▪ Incomplete dominance, leakage, penetrance, genes ― being part of longer DNA molecules ― are expressivity ▪ Hybridization: viability © 2020 Association of American Medical Colleges 30  organized, along with various proteins, into ▪ Gene pool biomolecular assemblies called chromosomes. Meiosis and Other Factors Affecting Genetic Chromosomes pass from parents to offspring in Variability (BIO) sexually reproducing organisms. The processes of ▪ Significance of meiosis meiosis and fertilization maintain a species’ ▪ Important differences between meiosis and chromosome count during the sexual life cycle. mitosis Because parents pass on discrete heritable units that ▪ Segregation of genes retain their separate identities in offspring, the laws of o Independent assortment probability can be used to predict the outcome of o Linkage some, but not all, genetic crosses. o Recombination The behavior of chromosomes during meiosis and ▪ Single crossovers fertilization is responsible for most of the genetic ▪ Double crossovers variation that arises each generation. Mechanisms that ▪ Synaptonemal complex contribute to this genetic variation include ▪ Tetrad independent assortment of chromosomes, crossing o Sex-linked characteristics over, and random fertilization. Other mechanisms, such o Very few genes on Y chromosome as mutation, random genetic drift, bottlenecks, and o Sex determination immigration, exist with the potential to affect the o Cytoplasmic/extranuclear inheritance genetic diversity of individuals and populations. ▪ Mutation Collectively, the genetic diversity that results from o General concept of mutation — error in DNA these processes provides the raw material for evolution sequence by natural selection. o Types of mutations: random, translation error, transcription error, base substitution, inversion, The content in this category covers the mechanisms by addition, deletion, translocation, mispairing which heritable information is transmitted from o Advantageous vs. deleterious mutation generation to generation and the evolutionary o Inborn errors of metabolism processes that generate and act on genetic variation. o Relationship of mutagens to carcinogens ▪ Genetic drift ▪ Synapsis or crossing-over mechanism for increasing genetic diversity Analytic Methods (BIO) ▪ Hardy-Weinberg Principle ▪ Testcross (Backcross; concepts of parental, F1, and F2 generations) ▪ Gene mapping: crossover frequencies ▪ Biometry: statistical methods © 2020 Association of American Medical Colleges 31  Evolution (BIO) ▪ Natural selection o Fitness concept o Selection by differential reproduction o Concepts of natural and group selection o Evolutionary success as increase in percentage representation in the gene pool of the next generation ▪ Speciation o Polymorphism o Adaptation and specialization o Inbreeding o Outbreeding o Bottlenecks ▪ Evolutionary time as measured by gradual random changes in genome 1D: Principles of bioenergetics and fuel molecule Principles of Bioenergetics (BC, GC) metabolism ▪ Bioenergetics/thermodynamics Living things harness energy from fuel molecules in a ▪ Free energy/Keq controlled manner that sustains all the processes o Equilibrium constant responsible for maintaining life. Cell maintenance and o Relationship of the equilibrium constant and growth is energetically costly. Cells harness the energy ΔG° stored in fuel molecules, such as carbohydrates and ▪ Concentration fatty acids, and convert it into smaller units of chemical o Le Châtelier’s Principle potential known as adenosine triphosphate (ATP). ▪ Endothermic and exothermic reactions ▪ Free energy: G The hydrolysis of ATP provides a ready source of energy ▪ Spontaneous reactions and ΔG° for cells that can be coupled to other chemical ▪ Phosphoryl group transfers and ATP processes that make them thermodynamically o ATP hydrolysis ΔG