MCAT Chemistry: Practice Questions, Topics & Study Tips

What Is MCAT Chemistry?

Chemistry concepts are tested within the AAMC's Chemical and Physical Foundations of Biological Systems (CPBS) section, where students must apply scientific knowledge to passage-based questions, experimental data, and unfamiliar scenarios. MCAT chemistry evaluates how you use scientific principles to analyze information and solve problems rather than emphasizing recall.  

"The most challenging aspect for me was definitely the application of knowledge. While I was confident in my understanding of the topics, applying the knowledge to complex scenarios presented in the questions was challenging. The questions often require applying memorized facts and concepts to analyze novel scenarios and solve problems, not just rote recall." – Dr. Cathleen Kuo, MD

Dr. Kuo's experience reflects a common challenge among MCAT test-takers: understanding the material is important but applying it under exam conditions is what the MCAT ultimately assesses.

Students looking for an in-depth breakdown of the foundational chemistry concepts that the CPBS section tests can explore our MCAT chemistry guide. If you're also reviewing the physical sciences tested in this section, our MCAT physics guide explains how the two disciplines differ on the MCAT.

Next, let's look at the chemistry topics that appear most frequently so you can do your MCAT prep effectively.

What Topics Are Tested in MCAT Chemistry?

MCAT chemistry covers topics ranging from stoichiometry, atomic structure, chemical bonding, thermodynamics, electrochemistry, laboratory techniques, and biologically relevant molecules. These topics often intersect with biology and other scientific disciplines.

Although chemistry and physics concepts are tested together, chemistry accounts for a larger share of the content students encounter on the CPBS section.

According to the AAMC, MCAT chemistry draws from several core subject areas that form the foundation of the Chemical and Physical Foundations section:

The above subject areas illustrate the range of chemistry concepts that can appear in MCAT chemistry passages and questions.

While these subtopics are often studied separately, MCAT passages frequently combine concepts from multiple areas of chemistry and biology. For example, a single passage may require you to interpret experimental data, apply general chemistry principles, and evaluate the biological significance of a reaction or process.

If you're deciding where to focus your study time, our guide to high-yield MCAT topics breaks down the concepts that appear most frequently across the exam. Because many CPBS passages also draw on biological concepts, reviewing MCAT biology questions can help you become more comfortable applying scientific knowledge across disciplines.

MCAT Chemistry Practice Questions

Test your knowledge with the MCAT chemistry passage and questions below. Complete each question before reviewing the answer explanations at the end of the section.

MCAT Chemistry Sample Passage

The heme enzyme indoleamine 2,3 dioxygenase (IDO) catalyzes Reaction 1, the first and rate-determining step of L-tryptophan (Compound 1) metabolism and is an important enzyme of the human immune system.

The IDO-catalyzed oxidation of Compound 1 by H2O2 does not occur. However, researchers have recently discovered that IDO-catalyzed oxidation of indole (Compound 3) by H2O2 (Reaction 2) does occur.

Under the conditions employed, the number of catalytic turnovers appeared to stop at roughly 100, on average. A plot of the concentration of Compound 3 that was oxidized versus the concentration of H2O2 employed, at two different initial concentrations of IDO, gave the results shown in Figure 1.

Aerobic oxidation of Compound 3 in the presence of 18O-labeled H218O2 resulted in the formation of 18O-labeled oxidation products (Table 1).

The formation of Compound 6 does not appear to be the result of a sequential oxidation process. Isotopically labeled Compound 4 does not exchange 18O for 16O in water over 3 hours, but Compound 6 completely loses its 18O label in unlabeled water over the same time period.

Passage adapted from Kuo HH, Mauk AG. Indole peroxygenase activity of indoleamine 2,3-dioxygenase. Proceedings of the National Academy of Sciences of the United States of America. 2012;109(35):13966–71.

Sample MCAT Chemistry Questions and Answers

1. The progress of Reaction 2 can be monitored by observing what change to the IR spectrum of the product mixture?

A) Appearance of a broad peak at 3400 cm–1

B) Disappearance of a broad peak at 3400 cm–1

C) Appearance of a sharp peak at 1700–1750 cm–1

D) Disappearance of a sharp peak at 1700–1750 cm–1

2. Which experiment can be used to show that Compound 6 is not formed sequentially from either Compound 4 or Compound 5?

A) Conduct the reaction of Compound 4 with Compound 5 and identify the products.

B) Oxidize Compound 4 and Compound 5 with IDO/H2O2 and identify the products.

C) Reduce pure Compound 6 without added catalyst and identify the products.

D) Conduct the reaction of Compound 2 with H2O2 without added catalyst and identify the products.

3. In Michaelis-Menten enzyme kinetics, what is the velocity of the reaction when the substrate concentration is equal to KM?

A) ¼Vmax

B) ½Vmax

C) Vmax

D) 2Vmax

4. 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 this data, what is the approximate number of capillaries in a human body?

A) 1 × 104

B) 2 × 107

C) 4 × 109

D) 7 × 1012

5. 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

6. The following kinetic parameters were obtained for the IDO-catalyzed oxidation of Compound 3 by H2O2 in the presence of L-Trp.

Based on this data, what effect does L-Trp have on the reaction?

A) L-Trp oxidizes Compound 3 directly.

B) L-Trp is oxidized instead of Compound 3.

C) L-Trp does not interact with the enzyme.

D) L-Trp inhibits the enzyme.

7. Four different solutions of a single amino acid were titrated, and the pK values of the solute were determined.

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

Check your answers below!

Want a broader overview of the CPBS section? Review the infographic below.

MCAT Chemistry Strategies

Three preparation habits consistently help students perform better on MCAT chemistry questions: passage-based practice, test-day simulation, and mastery of units, equations, and scientific notation.

Prioritize Passage-Based Practice

Regular practice with passage-based questions helps you become more comfortable identifying relevant information and applying your knowledge under exam conditions.

“Brushing up on my content knowledge through undergraduate courses (Organic Chemistry I and II) helped. Doing passage-based questions to then apply this knowledge in MCAT-form further reinforced this … Watching relevant videos helped to keep organic chemistry 'fun' while working on my knowledge base.” – Dr. Neel Mistry, MD

If you're planning your preparation timeline, follow an MCAT study schedule that balances content review, practice questions, and full-length exams.

Practice Under Realistic Testing Conditions

The CPBS section requires you to solve problems without a calculator while managing strict time constraints. Practicing under realistic testing conditions improves both pacing and confidence on exam day.

“Just think about it like you're an athlete – you have to prepare under realistic conditions if you want to get the best performance.” – Rishi, former BeMo student

For a broader preparation framework, see our guide on how to study for the MCAT alongside AAMC's overview of the CPBS section.

Master Units, Equations, and Scientific Notation

Many chemistry questions can be solved more efficiently when you recognize unit relationships, understand scientific notation, and quickly identify the appropriate equation. Small calculation errors may lead to incorrect answers even when you understand the underlying concept.

"Creating detailed diagrams for each topic and an equation sheet with key formulas helped me visualize and recall information quickly. Explaining concepts to myself out loud also solidified my understanding ... I incorporated short breaks with activities like going for walks or listening to science podcasts. I also found physics-related documentaries and engaging YouTube channels that helped me learn in a more interactive way." – Dr. Cathleen Kuo, MD.

For a complete breakdown of formulas, conversions, and calculations commonly tested in this section, review our MCAT chemistry equations guide.

Because the MCAT provides access to a periodic table on exam day, you can also familiarize yourself with its layout and features using our MCAT periodic table guide.

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Source: AAMC Sample Question Guide