This guide breaks down all 4 Medical College Admission Test (MCAT®) sections in the order they are administered, including the MCAT topics tested, discipline weightings, question counts, and the foundational concepts the Association of American Medical Colleges (AAMC®) uses to organize each section’s content. Whether you are just starting to learn what the MCAT covers or refining your preparation strategy, the breakdown below gives you the complete picture.
MCAT® Sections Overview and Structure
The MCAT is divided into 4 sections administered in a fixed order. The total exam, including breaks, runs approximately 7 hours and 30 minutes. Below is an at-a-glance summary of the MCAT structure before the full breakdown of each section.
MCAT Sections at a Glance
| Section | Name | Questions | Time |
|---|---|---|---|
| 1 | Biological and Biochemical Foundations of Living Systems | 59 | 95 minutes |
| 2 | Chemical and Physical Foundations of Biological Systems | 59 | 95 minutes |
| 3 | Psychological, Social, and Biological Foundations of Behavior | 59 | 95 minutes |
| 4 | Critical Analysis and Reasoning Skills (CARS) | 53 | 90 minutes |
| Total | - | 230 questions | 375 minutes |
The exam also includes optional breaks between sections and a lunch break. Total seat time including breaks and administrative tasks is approximately 7 hours and 30 minutes.
MCAT Sections in Order
The MCAT sections are always administered in the same fixed sequence. You cannot choose your section order or skip ahead. The order is:
- Biological and Biochemical Foundations of Living Systems — 95 minutes
- Chemical and Physical Foundations of Biological Systems — 95 minutes
- Psychological, Social, and Biological Foundations of Behavior — 95 minutes
- Critical Analysis and Reasoning Skills (CARS) — 90 minutes
Knowing this order matters for your test-day strategy. The CARS section comes last among the 4 sections (in the afternoon), so many students plan their energy and focus accordingly.
What Subjects Are on the MCAT?
Across all 4 sections, the MCAT subjects covers the following.
- Biology: Cell biology, molecular biology, genetics, anatomy, physiology, and evolution
- Biochemistry: Amino acids, proteins, enzymes, metabolism, and molecular genetics
- General chemistry: Atomic structure, stoichiometry, thermodynamics, and electrochemistry
- Organic chemistry: Functional groups, reactions, stereochemistry, and laboratory techniques
- Physics: Mechanics, electricity, magnetism, waves, optics, and thermodynamics
- Psychology: Biological bases of behavior, perception, cognition, motivation, and development
- Sociology: Social structures, group behavior, demographics, and social inequality
- Critical analysis and reasoning: No subject-specific knowledge required; passage-based only
Biology and biochemistry represent the largest share of the exam overall, followed by chemistry and physics in Section 2, and psychology and sociology in Section 3.
MCAT Sections Detailed Breakdown
The topics covered vary by MCAT section, organized around foundational concepts defined by the AAMC. Each section tests both content knowledge and the ability to apply scientific reasoning. Below is the full breakdown for each of the 4 sections.
Section 1: Biological and Biochemical Foundations of Living Systems
This section focuses on the biological and biochemical processes that are fundamental to living organisms, from cellular and molecular biology to organ system function.
| Questions | 59 multiple-choice (passage-based and discrete) | ||
| Time | 95 minutes | ||
|
Disciplines |
Introductory biology: 65% First-semester biochemistry: 25% General chemistry: 5% Organic chemistry: 5% |
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|
Scientific Inquiry & Reasoning Skills |
Skill 1: 35% Skill 2: 45% Skill 3: 10% Skill 4: 10% |
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|
Foundational Concepts |
Concept 1: 55% Concept 2: 20% Concept 3: 25% |
What this section covers:
Section 1 tests processes unique to living organisms: maintaining homeostasis, growth and reproduction, acquiring energy, sensing and responding to the environment, and adapting. It also covers how cells and organ systems work together to accomplish these processes. You must reason about biological processes at multiple levels of organization, molecular, cellular, and systemic.
Topics You Need to Know:
- Introductory-level biology, organic chemistry, and inorganic chemistry
- First-semester biochemistry (amino acids, proteins, enzymes, carbohydrates, lipids, and nucleic acids)
- Cellular and molecular biology (usually covered in introductory biology and first-semester biochemistry)
- Basic research methods and statistics
- Scientific inquiry and reasoning applied to the natural sciences
Section 2: Chemical and Physical Foundations of Biological Systems
This section covers the chemical and physical principles that underlie biological processes, from atomic structure to the mechanical properties of biological systems.
|
Questions |
59 multiple-choice (passage-based and discrete) |
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|
Time |
95 Minutes |
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|
Disciplines |
Introductory biology: 5% First-semester biochemistry: 25% General chemistry: 30% Organic chemistry: 15% Introductory physics: 25% |
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|
Scientific Inquiry & Reasoning Skills |
Skill 1: 35% Skill 2: 45% Skill 3: 10% Skill 4: 10% |
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|
Foundational Concepts |
Concept 4: 40% Concept 5: 60% |
What this section covers:
Section 2 applies principles of general chemistry, organic chemistry, and physics to biological systems. It tests your understanding of how atoms interact, how molecules are structured, and how physical forces govern biological processes such as circulation, respiration, and neural transmission.
Topics you need to know:
- General chemistry (atomic structure, periodic trends, bonding, solutions, thermodynamics, kinetics, and electrochemistry)
- Organic chemistry (functional groups, reaction mechanisms, stereochemistry, and spectroscopy)
- Introductory physics (mechanics, fluids, electricity, magnetism, waves, optics, and thermodynamics)
- First-semester biochemistry (especially as it relates to chemical structure and reactivity)
- Basic research methods and statistics
Section 3: Psychological, Social, and Biological Foundations of Behavior
This section covers how psychological, social, and biological factors shape human behavior, and how those factors influence health outcomes and interactions in medical settings.
|
Questions |
59 multiple-choice (passage-based and discrete) |
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|
Time |
95 minutes |
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|
Disciplines |
Introductory psychology: 65% Introductory sociology: 30% Introductory biology: 5% |
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Scientific Inquiry & Reasoning Skills |
Skill 1: 35% Skill 2: 45% Skill 3: 10% Skill 4: 10% |
||
|
Foundational Concepts |
Concept 6: 25% Concept 7: 35% Concept 8: 20% Concept 9: 15% Concept 10: 5% |
What this section covers:
Section 3 tests how psychological, sociocultural, and biological factors influence behavior, perception, and cognition. It also covers how these factors affect health and interact with the healthcare system. Compared to the first 2 sections, Section 3 has a higher proportion of content that many pre-medical students encounter for the first time.
Topics you need to know:
- Introductory psychology (biological bases of behavior, sensation and perception, cognition, emotion, motivation, development, personality, psychological disorders, and social psychology)
- Introductory sociology (social structures, culture, demographics, social inequality, social institutions, and health disparities)
- Introductory-level biology as applied to behavior (neuroscience, endocrinology, and genetics of behavior)
- Research methods in the social sciences
Section 4: Critical Analysis and Reasoning Skills (CARS)
The CARS section is unique among the 4 MCAT sections. It tests reading comprehension and analytical reasoning using passages from the humanities and social sciences. No prior subject knowledge is required or helpful.
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Questions |
53 multiple-choice (all passage-based) |
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Time |
90 minutes |
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Disciplines |
Humanities: 50% Social Sciences: 50% |
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|
Required Skills |
Foundations of Comprehension: 30% Reasoning within the Text: 30% Reasoning beyond the Text: 40% |
What this section covers:
CARS contains 9 passages, each approximately 500 to 600 words, followed by 5 to 7 questions per passage. The passages cover a wide range of topics from the humanities and social sciences. No outside knowledge is needed or tested. All answers must be grounded in the passage text.
This section measures the analytical and reasoning skills required in medical school: the ability to understand complex arguments, identify assumptions, evaluate evidence, and apply ideas to new situations.
Topics you need to know:
Unlike the science sections, CARS has no subject-specific content outline. Improvement comes through deliberate reading practice. Engage regularly with dense, complex texts in philosophy, history, cultural criticism, and the social sciences. Timed practice with authentic MCAT-style passages is the most effective preparation strategy for this section.
MCAT Topics and How They Are Tested
The MCAT does not simply test memorized facts. All 4 sections use a skill-based framework defined by the AAMC. Understanding how topics are tested, not just what is tested, is essential for efficient preparation.
The 4 MCAT Scientific Inquiry and Reasoning Skills
The first 3 sections each test 4 skills in defined proportions:
| Skill | Description | Approximate % per Science Section |
|---|---|---|
| Skill 1 | Knowledge of scientific concepts and principles | 35% |
| Skill 2 | Scientific reasoning and problem solving | 45% |
| Skill 3 | Reasoning about the design and execution of research | 10% |
| Skill 4 | Data-based and statistical reasoning | 10% |
Skill 2 accounts for the largest share, meaning the majority of science questions require applying and reasoning about concepts, not just recalling them. Pure memorization is not enough to score well on the MCAT.
Passage-Based vs. Discrete Questions
Across the first 3 sections, questions appear in 2 formats:
- Passage-based questions: A set of questions tied to a reading passage describing an experiment, research finding, or scientific scenario. These require you to integrate passage information with your content knowledge.
- Discrete questions: Standalone questions not tied to a passage. These typically test direct application of a concept or principle.
The CARS section uses only passage-based questions. There are no discrete questions in CARS.
Scientific Inquiry and Reasoning Skills
The MCAT is designed to examine your ability to combine scientific knowledge with skills in scientific inquiry and reasoning. This must be demonstrated across 4 such skills that natural, behavioral, and social scientists rely on to advance their work. They are tested in each MCAT section other than CARS, and include the following:
Skill 1 requires examinees to:
- Demonstrate their understanding of scientific concepts and principles
- Identify the relationships between closely related concepts
Skill 2 requires examinees to:
- Reason about scientific principles, theories, and models
- Analyze and evaluate scientific explanations and predictions
Skill 3 requires examinees to:
- Demonstrate an understanding of important components of scientific research
- Reason about ethical issues in research
Skill 4 requires examinees to:
- Interpret patterns in data presented in tables, figures, and graphs
- Reason about data and draw conclusions from it
MCAT Foundational Concepts
The MCAT features 10 foundational concepts that cover “big ideas” in the sciences, and ask students to integrate and analyze information from different disciplines. They apply to each section of the exam other than CARS. Below is an outline of what to expect from the MCAT’s Foundational Concepts:
The first foundational concept examined on the MCAT makes up 55% of the Biological and Biochemical Foundations of Living Systems section. It’s defined by the AAMC as follows:
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.
- Structure and function of proteins and their constituent amino acids
- Transmission of genetic information from the gene to the protein
- Transmission of heritable information from generation to generation and the processes that increase genetic diversity
- Principles of bioenergetics and fuel molecule metabolism
The second foundational concept examined on the MCAT makes up 20% of the Biological and Biochemical Foundations of Living Systems section. It’s defined by the AAMC as follows:
Highly organized assemblies of molecules, cells, and organs interact to carry out the functions of living organisms.
- Assemblies of molecules, cells, and groups of cells within single, cellular, and multicellular organisms
- The structure, growth, physiology, and genetics of prokaryotes and viruses
- Processes of cell division, differentiation, and specialization
The third foundational concept examined on the MCAT makes up 25% of the Biological and Biochemical Foundations of Living Systems section. It’s defined by the AAMC as follows:
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.
- Structure and functions of the nervous and endocrine systems and ways these systems coordinate the organ systems
- Structure and integrative functions of the main organ systems
The fourth foundational concept examined on the MCAT makes up 40% of the Chemical and Physical Foundations of Biological Systems section. It’s defined by the AAMC as follows:
Complex living organisms transport materials, sense their environment, process signals, and respond to changes using processes understood in terms of physical principles.
- Translational motion, forces, work, energy, and equilibrium in living systems
- Importance of fluids for the circulation of blood, gas movement, and gas exchange
- Electrochemistry and electrical circuits and their elements
- How light and sound interact with matter
- Atoms, nuclear decay, electronic structure, and atomic chemical behavior
The fifth foundational concept examined on the MCAT makes up 60% of the Chemical and Physical Foundations of Biological Systems section. It’s defined by the AAMC as follows:
The principles that govern chemical interactions and reactions form the basis for a broader understanding of the molecular dynamics of living systems.
- Unique nature of water and its solutions
- Nature of molecules and intermolecular interactions
- Separation and purification methods
- Structure, function, and reactivity of biologically relevant molecules
- Principles of chemical thermodynamics and kinetics
The sixth foundational concept examined on the MCAT makes up 25% of the Psychological, Social, and Biological Foundations of Behavior section. It’s defined by the AAMC as follows:
Biological, psychological, and sociocultural factors influence the ways that individuals perceive, think about, and react to the world.
- Sensing the environment
- Making sense of the environment
- Responding to the world
The seventh foundational concept examined on the MCAT makes up 35% of the Psychological, Social, and Biological Foundations of Behavior section. It’s defined by the AAMC as follows:
Biological, psychological, and sociocultural factors influence behavior and behavior change.
- Individual influences on behavior
- Social processes that influence human behavior
- Attitude and behavior change
The eighth foundational concept examined on the MCAT makes up 20% of the Psychological, Social, and Biological Foundations of Behavior section. It’s defined by the AAMC as follows:
Psychological, sociocultural, and biological factors influence the way we think about ourselves and others, as well as how we interact with others.
- Self-identity
- Social thinking
- Social interactions
The ninth foundational concept examined on the MCAT makes up 15% of the Psychological, Social, and Biological Foundations of Behavior section. It’s defined by the AAMC as follows:
Cultural and social differences influence well-being.
- Understanding social structure
- Demographic characteristics and processes
The tenth foundational concept examined on the MCAT makes up 5% of the Psychological, Social, and Biological Foundations of Behavior section. It’s defined by the AAMC as follows:
Social stratification and access to resources influence well-being.
- Social inequality
What Math Skills Are Tested on the MCAT?
Math on the MCAT is constrained to general mathematical concepts and techniques. For example, you will not need to understand calculus, but you will need to understand the following (as provided by the AAMC):
- 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).
Frequently Asked Questions about MCAT Sections (FAQs)
What are the 4 sections of the MCAT?
The MCAT has 4 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 (CARS)
The first 3 sections test science knowledge across biology, biochemistry, chemistry, physics, psychology, and sociology. CARS tests reading comprehension and analytical reasoning only.
