What Are the Four MCAT^® Sections?

The MCAT^® has four scored sections: Chemical and Physical Foundations of Biological Systems (Chem/Phys), Critical Analysis and Reasoning Skills (CARS), Biological and Biochemical Foundations of Living Systems (Bio/Biochem), and Psychological, Social, and Biological Foundations of Behavior (Psych/Soc). The three science sections each give you 59 questions in 95 minutes, and CARS gives you 53 reading questions in 90 minutes that need no outside knowledge.

You take them in that order, and each one is scored from 118 to 132. The names are long, but the sections are easier to plan for once you know what each one pulls from and how its questions are built.

The Four Sections at a Glance

That's 230 questions in all. The three science sections share one structure: according to the AAMC's exam overview, each has 10 passage sets of 4 to 6 questions plus 15 independent questions, which are standalone questions with no passage. That leaves 44 passage questions spread over 10 passages, an average of 4.4 per passage.

CARS works differently. It has 9 passages with 5 to 7 questions each and no standalone questions at all. The four sections add up to 6 hours and 15 minutes of testing, and with breaks, the tutorial and the check-in steps, you're seated for about 7 hours and 30 minutes. The test-day timeline walks through each block.

Chem/Phys: Physics and Chemistry Applied to the Body

The AAMC's content outline for Chem/Phys splits the section like this:

• General chemistry: 30 percent
• Introductory physics: 25 percent
• First-semester biochemistry: 25 percent
• Organic chemistry: 15 percent
• Introductory biology: 5 percent

The outline organizes that content under two foundational concepts. Concept 4, at 40 percent, covers how living organisms transport materials, sense their environment and process signals, understood "in terms of physical principles." Concept 5, at 60 percent, covers the chemical interactions and reactions behind the molecular dynamics of living systems. So the physics and chemistry you see will usually come attached to a biological system.

The outline also sets the math ceiling. Calculus isn't required, and a periodic table is provided during the exam. You're expected to handle Algebra II-level exponents, logarithms and scientific notation, basic trigonometry, vector addition and subtraction, significant figures, unit conversions and graphs on a log scale.

CARS: Reading and Reasoning, No Content

CARS is the only section that doesn't test what you learned in a class. The AAMC's CARS outline says "no additional coursework or specific knowledge is required." Every answer comes from the passage in front of you.

Passages are typically 500 to 600 words. About half come from the humanities and half from the social sciences, though the split varies from test to test. Kaplan's summary of the section lists the fields: ethics, literature, music, philosophy and religion on the humanities side, and anthropology, economics, history, linguistics and political science on the social science side.

The questions test three skills:

• Foundations of Comprehension: about 30 percent. What does the passage say, and what does a word or sentence mean in context?
• Reasoning Within the Text: about 30 percent. How do the author's claims and evidence fit together?
• Reasoning Beyond the Text: about 40 percent. How would the author's ideas apply to a new situation, or how would new information change them?

The biggest share goes to applying the author's ideas beyond the passage, so understanding what the text says only gets you through 30 percent of the questions. On timing, 90 minutes over 9 passages gives you 10 minutes per passage, reading included. If your CARS practice scores stopped moving, the plateau breakdown covers why that happens and what to change.

Bio/Biochem: Mostly Biology, Built on Molecules

The Bio/Biochem outline gives the section's content split:

• Introductory biology: 65 percent
• First-semester biochemistry: 25 percent
• General chemistry: 5 percent
• Organic chemistry: 5 percent

The foundational concepts tell a different story from the course labels. Concept 1, on how biomolecules' properties shape cells and life processes, makes up 55 percent of the section. Concept 2, on how assemblies of molecules, cells and organs carry out an organism's functions, is 20 percent. Concept 3, on how organ systems sense the environment and keep the internal environment stable, is 25 percent.

That means more than half of Bio/Biochem is about molecules. Biochemistry also makes up 25 percent of Chem/Phys, so it shows up in two sections, while organic chemistry stays small in both.

Psych/Soc: Psychology First

The Psych/Soc outline assumes one semester of introductory psychology, one semester of introductory sociology and a two-semester introductory biology sequence. The content splits 65 percent psychology, 30 percent sociology and 5 percent biology, and the biology is limited to concepts tied to mental processes and behavior.

The section has five foundational concepts:

Concepts 6 through 8, on how individuals perceive, behave and relate to others, cover 80 percent of the section. Concepts 9 and 10, on culture, social differences and stratification, add up to the other 20 percent.

The Skills Behind the Science Questions

All three science sections use the same four scientific inquiry and reasoning skills, in the same proportions, according to each section's outline:

Skill 1 is closest to straight recall, and it's 35 percent of the science questions, or about 62 of the 177. The other 65 percent ask you to apply what you know, judge a study or read data. That split is the case against spending months on content review with little time left for practice questions.

All of the AAMC's percentages are approximate. The outlines round them to the nearest 5 percent and note that they vary from one test form to another.

Which Subjects Show Up Most?

Each outline describes one section, so no single AAMC table shows how much of the exam each subject gets. You can estimate it by multiplying each discipline's share in each section by 59 questions and adding up the sections. Here's what that gives you.

Where the science questions come from

Estimated questions per discipline across the three 59-question science sections

Biology leads with about 44 questions, because it appears in all three science sections. Psychology comes second, about 38, from Psych/Soc alone. Organic chemistry is last at about 12, which is roughly 5 percent of the 230 questions on the exam.

That ranking is useful when you split up your study time. A study schedule that gives orgo the same weeks as biology is spending time where the test spends little of it. CARS doesn't appear in the chart because it has no content, but its 53 questions count as one full section of your score.

How the Sections Add Up to Your Score

Each section is scored from 118 to 132, and the four scores add up to a total from 472 to 528. CARS counts exactly as much as each science section even though it has 6 fewer questions.

Your score report lists all four section scores next to the total, each with its own percentile rank. A weak CARS score shows up there on its own line, so it's worth giving CARS regular practice time instead of counting on the science sections to cover for it.

Quick Answers

• What order are the sections in? Chem/Phys, CARS, Bio/Biochem, then Psych/Soc.
• How many questions are on the MCAT? 230: 59 in each science section and 53 in CARS.
• Do you need calculus? No. The AAMC says calculus isn't required, and you get a periodic table during the exam.
• Does CARS need outside knowledge? No. Every answer is supported by the passage.
• What's a discrete question? The AAMC calls them independent questions: standalone items with no passage. Each science section has 15.

To study each section topic by topic, use the PurpleCAT concept library, which is organized around the AAMC content outline.

Last verified October 29, 2026, against the AAMC's exam overview and its content outlines for each section.

Sources

• AAMC, What's on the MCAT Exam?
• AAMC, Chemical and Physical Foundations of Biological Systems (content outline)
• AAMC, Critical Analysis and Reasoning Skills (content outline)
• AAMC, Biological and Biochemical Foundations of Living Systems (content outline)
• AAMC, Psychological, Social, and Biological Foundations of Behavior (content outline)
• Kaplan, What's Tested on the MCAT: CARS
• UWorld, MCAT Score Range, Scoring, and Percentiles