The MCAT Chem/Phys Textbook

Everything the Chemical and Physical Foundations of Biological Systems section actually tests — the physics, the chemistry, and how AAMC wraps them in biology

Take the quick quiz

The one thing to internalize

Chem/Phys is an applied-reasoning test, not a plug-and-chug test. The equations are simple — what's hard is reading a passage about, say, blood flow or a reaction calorimeter and recognizing which simple equation it's secretly asking about, then reasoning about a change (double the radius, halve the temperature) without a calculator. Two habits make most of the section tractable: know your formulas as relationships, not just symbols (what's proportional to what, and what happens when one variable changes), and practice unit reasoning and estimation — most of the "math" is dimensional analysis and powers of ten, which you can do in your head once you stop reaching for a calculator you don't have.

A quieter fact: a meaningful slice of these questions are really data and graph interpretation — read the axes, find the slope or intercept, predict the trend. Fluency there turns the long quantitative passages into fast ones.

The Chem/Phys section at a glance

Section name	Chemical and Physical Foundations of Biological Systems
Questions	59 (mix of passage-based and discrete)
Time	95 minutes
Score range	118–132 (part of the 472–528 total)
Draws on	General chemistry ~30%, physics ~25%, biochemistry ~25%, organic chemistry ~15%, biology ~5%

The section is built from two foundational concepts (numbered 4–5), weighted as follows. The weighting is your highest-level study-priority map — spend time in proportion to it:

Foundational concept	Theme	Exam weight
FC4	Physical principles of living systems — motion, fluids, circuits, light & sound, atoms	40%
FC5	The chemistry of life — water, bonding, separations, organic reactivity, thermodynamics & kinetics	60%

FC5 is the heavier concept (60%) and is mostly chemistry — but FC4's physics is where the section's reputation for being "math-heavy" comes from, so this textbook builds out 4A first as its template (and to anchor the physics tools the rest of FC4 reuses).

How to study Chem/Phys (section-specific tactics)

The plan lives in the Study Plan Playbook. This adds only the tactics specific to this content:

Relationships over formulas. Don't just memorize Q = ΔP·πr⁴/8ηL — internalize that flow scales with the fourth power of radius, because the question will halve the radius and ask what happens to flow.
Drill calculator-free math. Powers of ten, simple log/antilog (for pH and decibels), trig of common angles, and estimation. The arithmetic is the bottleneck, not the physics.
Master unit analysis. Most quantitative items can be solved — or distractors eliminated — by tracking units alone.
Read graphs out loud. Name the axes, the slope, and the intercept. A huge share of points are "what does this curve do when X changes."
Biochem and acid–base are shared, high-yield ground. The thermodynamics, enzyme-kinetics, and amino-acid material here is also tested in Bio/Biochem — learn it once, thoroughly.
Organic is recognition, not synthesis. MCAT orgo rewards spotting functional groups, predicting whether a mechanism is favorable, and reading spectra — not multi-step synthesis. Study it as pattern recognition.

The chapters

FC4 — Physical principles of living systems

40% of section

4A Translational motion, forces, work, energy, and equilibrium in living systems Classical mechanics applied to bodies and biological structures: how to describe motion (kinematics), what changes it (forces and Newton's laws), the condition for balance (translational and rotational equilibrium, including the body's levers), and the bookkeeping of energy (work, kinetic and potential energy, conservation, and power). 4B Fluids, circulation, and gas exchange Fluids at rest (pressure, Pascal's principle, buoyancy) and in motion (the continuity equation, Bernoulli's principle, and Poiseuille resistance), applied to the body's plumbing — the circulatory system and gas exchange in the lungs. 4C Electrochemistry and circuits Static charge and fields (Coulomb's law, electric field vs. potential), the rules of DC circuits (Ohm's law, series vs. parallel, power, capacitors), and electrochemical cells (galvanic vs. electrolytic, reduction potentials, the Nernst equation) — the bridge where physics and general chemistry meet. 4D Light and sound Wave behavior and its two MCAT showcases: sound (a longitudinal pressure wave — intensity, decibels, the Doppler effect) and light (an electromagnetic wave — reflection, refraction, total internal reflection, and image formation by lenses and mirrors). 4E Atoms, nuclear decay, and electronic structure The atom from the inside out: its particles and isotopes, the quantum description of its electrons (quantum numbers, orbitals, electron configuration), the periodic trends that fall out of that structure, and the nuclear phenomena — radioactive decay, half-life, and mass–energy — that come from the nucleus.

FC5 — The chemistry of life

60% of section

5A Water and its solutions Water's polarity and hydrogen bonding make it the universal biological solvent — and set up the chapter's high-yield core: acid–base chemistry (pH, strong vs. weak, buffers, titrations) and solutions (solubility, Ksp, colligative properties). 5B Molecules and intermolecular interactions How atoms bond into molecules (ionic, covalent, polarity, Lewis structures, VSEPR shape, hybridization) and how molecules stick to each other (the intermolecular forces that set boiling point, melting point, and solubility). 5C Separation and purification Lab methods that separate mixtures by exploiting a physical difference — extraction (polarity/solubility), distillation (boiling point), chromatography (affinity for a stationary vs. mobile phase), and gel electrophoresis (size and charge). Mostly recognition points: know what each separates by. 5D Organic structure and reactivity Organic chemistry as the MCAT tests it: recognizing functional groups, reading stereochemistry (chirality, R/S, enantiomers vs. diastereomers), predicting reactivity (nucleophiles, electrophiles, carbonyl chemistry), the biological molecules built from all of it, and determining structure by spectroscopy. 5E Thermodynamics and kinetics The two questions every reaction faces: will it go? (thermodynamics — enthalpy, entropy, Gibbs free energy, equilibrium) and how fast? (kinetics — rate laws, activation energy, catalysis). They are independent: a spontaneous reaction can be immeasurably slow.

About this textbook

What this textbook is

The Study Plan Playbook is about the plan — how to sequence your prep, read your scores, and know when you're ready. This textbook is the other half: it teaches the content of the Chem/Phys section — the actual physics and chemistry you're tested on.

It's built around one organizing fact: Chem/Phys is a reasoning test that uses physics and chemistry as its vocabulary — most questions hand you a formula's worth of setup inside a biological passage and ask you to predict, compare, or compute. The section blends four sciences (general chemistry, physics, organic chemistry, and biochemistry), so the skill that scores is moving fluently between an equation and what it means for a living system. Every concept below is taught at two depths and tagged with how AAMC tests it, so you train application, not just recall.

How to read it

Every piece of content is a node with two depth levels and a few badges:

Short — the glance/cram version (a concept's one-liner). Read the Short lines top-to-bottom and you have the "condensed doc" experience.
Expanded — the full narrative treatment, for first-time learning and nuance.
Badges — quick tags on each node: what discipline it draws on (physics / gen chem / orgo / biochem / bio), how high-yield it is, what type of thing it is (term, theory, process, distinction), and a trap flag on the notorious confusions.
How AAMC tests it / Don't confuse / Related — the application layer, the reliable distractor pairs, and cross-links to related nodes.

Read a category once at Expanded depth for understanding, then review off the Short lines and the trap nodes.

How to use it alongside your other resources

This textbook maps one-to-one to the AAMC content outline (see the spine), the same skeleton used by the popular community resources. Use it as your primary read-through and concept reference; use a problem set for daily practice (Chem/Phys is the most calculation-heavy section, so drill the math); use AAMC and third-party question banks to practice the application layer. Note that biochemistry overlaps both science sections — the amino-acid, enzyme, and thermodynamics content here is also tested in Bio/Biochem, so learn it once and bank the points twice.