The MCAT Chemistry and Physics section is often feared by test-takers. Going over high-quality MCAT chemistry questions as part of your can significantly help build your confidence in this challenging section. This blog is the ultimate guide to understanding what is assessed in the first section of the MCAT and how to successfully prepare for it. We also include several MCAT chemistry and physics sample questions and expert answers.
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"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, SUNY Buffalo
So, what academic disciplines are covered in the Chemical and Physical Foundations of Biological Systems section—sometimes referred to simply as the “chemistry and physics” section—of the MCAT? Questions included in this section breakdown as follows:
The concepts are combined with scientific inquiry and reasoning skills. The CPBS section incorporates concepts taught in your introductory level chemistry courses and relates these concepts back to biology and physiology.
The chemistry and physics section covers the following foundational concepts:
- Complex living organisms transport materials, sense their environment, process signals, and respond to changes using processes understood in terms of physical principles
- The principles that govern chemical interactions and reactions form the basis for a broader understanding of the molecular dynamics of living systems
The AAMC’s overview of offers a detailed list of the subtopics included within each foundational concept of the Chemical and Physical Foundations of Biological Systems section of the MCAT. The CPBS section’s main subtopics include:
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.
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 Questions and Answers
Looking for more on what the chemistry and physics section looks like? Check this out:
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
Tip #1: Prep for Chemistry and Physics Data and Experiments
The AAMC typically tests students with chemistry and physics experiments in the form of passage-based questions. This means that you cannot just practice vocabulary and memorize equations. You must be able to apply your knowledge to a scenario in a passage. Regular practice with passage-based questions will help develop this skill.
“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, University of Ottawa Faculty of Medicine.
"I made a conscious effort to relate biology and chemistry concepts to real-life applications and examples. This not only enhanced my understanding but also kept me motivated to learn. I also incorporated variety into my study sessions by alternating between learning materials and practicing questions. This approach helped me stay focused and made the study process more enjoyable." – Dr. Cathleen Kuo, MD.
Tip #2: Mimic Test Day Conditions and Brush Up on Your Math Skills
You won’t have access to a calculator on exam day, so as you prepare for the MCAT it’s important that you complete practice questions in conditions that will mimic those of the test day. This means that since you will not have a calculator during the MCAT, don’t practice with a calculator! Brush up on math skills involving exponents, scientific notation, and multiplication and division of complex numbers. You will not have a calculator, but you will have access to the of elements, so be sure you know how to use it.
“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 and current student at Carver College of Medicine.
“Identify which topics you feel strongest and those you feel weakest. Then I would devote time to [reviewing] weaker topics while continually studying the stronger topics using flash cards or questions.” – Dr. Monica Taneja, MD, University of Maryland School of Medicine.
Tip #3: Know Your Units and Equations
Knowing your standard SI units and how to perform unit conversions seems basic, but they are foundational to understanding the context of MCAT questions. When feeling the exam approaching, you can easily start to panic if the answer you get is not among the answer choices. However, a simple unit conversion or a switch to scientific notation may reveal the correct answer. Similarly, you will need to know many foundational .
Using flashcards other active learning techniques can help you practice using and converting equations.
"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.
1. What is a good score on the chemistry and physics section of the MCAT?
The chemistry and physics section of the MCAT, like each of the four sections, is scored on a scale of 118-132, with the median score set at 125.
2. How much chemistry is on the MCAT?
The MCAT covers chemistry in two of its four sections: Chemical and Physical Foundations of Biological Systems, and Biological and Biochemical Foundations of Living Systems. Approximately 25% of the Chemical and Physical Foundations section focuses on general chemistry, while another 5% covers biochemistry.
3. How to study for the MCAT chemistry section?
To effectively study for the MCAT chemistry section, start by understanding the fundamental concepts in general and organic chemistry. Use official MCAT study materials for targeted practice, and supplement with additional resources like textbooks or online courses for deeper understanding. Regularly practice with MCAT-style questions to familiarize yourself with the test format and question types.
4. Is there specific coursework that I should take to prepare for the chemistry and physics section of the MCAT?
All of the content on the MCAT is covered in introductory courses at most universities. It is important to take these introductory courses to help build your knowledge base and confidence in these areas before taking the MCAT.
5. What are some techniques for memorizing the physics equations I will need on test day?
Here are some additional techniques to consider working into your MCAT preparation: write the equation down several times on a piece of paper until you can recite it out loud without referencing your study materials, complete several practice problems that require the use of the equation, try grouping several equations together by topic to see similarities between equations, or ask a friend if they have developed any catchy mnemonic devices to remember equations.
6. Can I use a calculator during the chemistry and physics section of the MCAT?
You will not be able to use a calculator for this section of the MCAT, which means that it is important that you do not complete sample questions or practice MCAT exams with a calculator.
7. What is a good way to remember formulas?
Make flash cards and focus on units - if you can get the correct units in your answer, you can probably figure out the correct formula.
8. Will I need to know how to draw molecules for the MCAT?
The MCAT is a multiple-choice test and does not contain any free-response questions where your knowledge of how to draw molecules will be tested.