MCAT General Chemistry Review - Alexander Stone Macnow, MD 2019-2020

About the MCAT


Here is a general overview of the structure of Test Day:


Number of Questions

Time Allotted

Test-Day Certification

4 minutes

Tutorial (optional)

10 minutes

Chemical and Physical Foundations of Biological Systems


95 minutes

Break (optional)

10 minutes

Critical Analysis and Reasoning Skills (CARS)


90 minutes

Lunch Break (optional)

30 minutes

Biological and Biochemical Foundations of Living Systems


95 minutes

Break (optional)

10 minutes

Psychological, Social, and Biological Foundations of Behavior


95 minutes

Void Question

3 minutes

Satisfaction Survey (optional)

5 minutes

The structure of the four sections of the MCAT is shown below.

Chemical and Physical Foundations of Biological Systems


95 minutes


· 59 questions

· 10 passages

· 44 questions are passage-based, and 15 are discrete (stand-alone) questions.

· Score between 118 and 132

What It Tests

· Biochemistry: 25%

· Biology: 5%

· General Chemistry: 30%

· Organic Chemistry: 15%

· Physics: 25%

Critical Analysis and Reasoning Skills (CARS)


90 minutes


· 53 questions

· 9 passages

· All questions are passage-based. There are no discrete (stand-alone) questions.

· Score between 118 and 132

What It Tests

· Disciplines:

o Humanities: 50%

o Social Sciences: 50%

· Skills:

o Foundations of Comprehension: 30%

o Reasoning Within the Text: 30%

o Reasoning Beyond the Text: 40%

Biological and Biochemical Foundations of Living Systems


95 minutes


· 59 questions

· 10 passages

· 44 questions are passage-based, and 15 are discrete (stand-alone) questions.

· Score between 118 and 132

What It Tests

· Biochemistry: 25%

· Biology: 65%

· General Chemistry: 5%

· Organic Chemistry: 5%

Psychological, Social, and Biological Foundations of Behavior


95 minutes


· 59 questions

· 10 passages

· 44 questions are passage-based, and 15 are discrete (stand-alone) questions.

· Score between 118 and 132

What It Tests

· Biology: 5%

· Psychology: 65%

· Sociology: 30%


Testing Time

375 minutes (6 hours, 15 minutes)

Total Seat Time

447 minutes (7 hours, 27 minutes)




472 to 528



The AAMC has defined four Scientific Inquiry and Reasoning Skills (SIRS) that will be tested in the three science sections of the MCAT:

1. Knowledge of Scientific Concepts and Principles (35% of questions)

2. Scientific Reasoning and Problem-Solving (45% of questions)

3. Reasoning About the Design and Execution of Research (10% of questions)

4. Data-Based and Statistical Reasoning (10% of questions)

Let's see how each one breaks down into more specific Test Day behaviors. Note that the bullet points of specific objectives for each of the SIRS are taken directly from the Official Guide to the MCAT Exam; the descriptions of what these behaviors mean and sample question stems, however, are written by Kaplan.

Skill 1: Knowledge of Scientific Concepts and Principles

This is probably the least surprising of the four SIRS; the testing of science knowledge is, after all, one of the signature qualities of the MCAT. Skill 1 questions will require you to do the following:

· Recognize correct scientific principles

· Identify the relationships among closely related concepts

· Identify the relationships between different representations of concepts (verbal, symbolic, graphic)

· Identify examples of observations that illustrate scientific principles

· Use mathematical equations to solve problems

At Kaplan, we simply call these Science Knowledge or Skill 1 questions. Another way to think of Skill 1 questions is as “one-step” problems. The single step is either to realize which scientific concept the question stem is suggesting or to take the concept stated in the question stem and identify which answer choice is an accurate application of it. Skill 1 questions are particularly prominent among discrete questions (those not associated with a passage). These questions are an opportunity to gain quick points on Test Day—if you know the science concept attached to the question, then that's it! On Test Day, 35% of the questions in each science section will be Skill 1 questions.

Here are some sample Skill 1 question stems:

· How would a proponent of the James—Lange theory of emotion interpret the findings of the study cited the passage?

· Which of the following most accurately describes the function of FSH in the human female menstrual cycle?

· If the products of Reaction 1 and Reaction 2 were combined in solution, the resulting reaction would form:

· Ionic bonds are maintained by which of the following forces?

Skill 2: Scientific Reasoning and Problem-Solving

The MCAT science sections do, of course, move beyond testing straightforward science knowledge; Skill 2 questions are the most common way in which it does so. At Kaplan, we also call these Critical Thinking questions. Skill 2 questions will require you to do the following:

· Reason about scientific principles, theories, and models

· Analyze and evaluate scientific explanations and predictions

· Evaluate arguments about causes and consequences

· Bring together theory, observations, and evidence to draw conclusions

· Recognize scientific findings that challenge or invalidate a scientific theory or model

· Determine and use scientific formulas to solve problems

Just as Skill 1 questions can be thought of as “one-step” problems, many Skill 2 questions are “two-step” problems, and more difficult Skill 2 questions may require three or more steps. These questions can require a wide spectrum of reasoning skills, including integration of multiple facts from a passage, combination of multiple science content areas, and prediction of an experiment's results. Skill 2 questions also tend to ask about science content without actually mentioning it by name. For example, a question might describe the results of one experiment and ask you to predict the results of a second experiment without actually telling you what underlying scientific principles are at work—part of the question's difficulty will be figuring out which principles to apply in order to get the correct answer. On Test Day, 45% of the questions in each science section will be Skill 2 questions.

Here are some sample Skill 2 question stems:

· Which of the following experimental conditions would most likely yield results similar to those in Figure 2?

· All of the following conclusions are supported by the information in the passage EXCEPT:

· The most likely cause of the anomalous results found by the experimenter is:

· An impact to a man's chest quickly reduces the volume of one of his lungs to 70% of its initial value while not allowing any air to escape from the man's mouth. By what percentage is the force of outward air pressure increased on a 2 cm2 portion of the inner surface of the compressed lung?

Skill 3: Reasoning About the Design and Execution of Research

The MCAT is interested in your ability to critically appraise and analyze research, as this is an important day-to-day task of a physician. We call these questions Skill 3 or Experimental and Research Design questions for short. Skill 3 questions will require you to do the following:

· Identify the role of theory, past findings, and observations in scientific questioning

· Identify testable research questions and hypotheses

· Distinguish between samples and populations and distinguish results that support generalizations about populations

· Identify independent and dependent variables

· Reason about the features of research studies that suggest associations between variables or causal relationships between them (such as temporality and random assignment)

· Identify conclusions that are supported by research results

· Determine the implications of results for real-world situations

· Reason about ethical issues in scientific research

Over the years, the AAMC has received input from medical schools to require more practical research skills of MCAT test-takers, and Skill 3 questions are the response to these demands. This skill is unique in that the outside knowledge you need to answer Skill 3 questions is not taught in any one undergraduate course; instead, the research design principles needed to answer these questions are learned gradually throughout your science classes and especially through any laboratory work you have completed. It should be noted that Skill 3 comprises 10% of the questions in each science section on Test Day.

Here are some sample Skill 3 question stems:

· What is the dependent variable in the study described in the passage?

· The major flaw in the method used to measure disease susceptibility in Experiment 1 is:

· Which of the following procedures is most important for the experimenters to follow in order for their study to maintain a proper, randomized sample of research subjects?

· A researcher would like to test the hypothesis that individuals who move to an urban area during adulthood are more likely to own a car than are those who have lived in an urban area since birth. Which of the following studies would best test this hypothesis?

Skill 4: Data-Based and Statistical Reasoning

Lastly, the science sections of the MCAT test your ability to analyze the visual and numerical results of experiments and studies. We call these Data and Statistical Analysis questions. Skill 4 questions will require you to do the following:

· Use, analyze, and interpret data in figures, graphs, and tables

· Evaluate whether representations make sense for particular scientific observations and data

· Use measures of central tendency (mean, median, and mode) and measures of dispersion (range, interquartile range, and standard deviation) to describe data

· Reason about random and systematic error

· Reason about statistical significance and uncertainty (interpreting statistical significance levels and interpreting a confidence interval)

· Use data to explain relationships between variables or make predictions

· Use data to answer research questions and draw conclusions

Skill 4 is included in the MCAT because physicians and researchers spend much of their time examining the results of their own studies and the studies of others, and it's very important for them to make legitimate conclusions and sound judgments based on that data. The MCAT tests Skill 4 on all three science sections with graphical representations of data (charts and bar graphs) as well as numerical ones (tables, lists, and results summarized in sentence or paragraph form). On Test Day, 10% of the questions in each science section will be Skill 4 questions.

Here are some sample Skill 4 question stems:

· According to the information in the passage, there is an inverse correlation between:

· What conclusion is best supported by the findings displayed in Figure 2?

· A medical test for a rare type of heavy metal poisoning returns a positive result for 98% of affected individuals and 13% of unaffected individuals. Which of the following types of error is most prevalent in this test?

· If a fourth trial of Experiment 1 was run and yielded a result of 54% compliance, which of the following would be true?

SIRS Summary

Discussing the SIRS tested on the MCAT is a daunting prospect given that the very nature of the skills tends to make the conversation rather abstract. Nevertheless, with enough practice, you'll be able to identify each of the four skills quickly, and you'll also be able to apply the proper strategies to solve those problems on Test Day. If you need a quick reference to remind you of the four SIRS, these guidelines may help:

Skill 1 (Science Knowledge) questions ask:

· Do you remember this science content?

Skill 2 (Critical Thinking) questions ask:

· Do you remember this science content? And if you do, could you please apply it to this novel situation?

· Could you answer this question that cleverly combines multiple content areas at the same time?

Skill 3 (Experimental and Research Design) questions ask:

· Let's forget about the science content for a while. Could you give some insight into the experimental or research methods involved in this situation?

Skill 4 (Data and Statistical Analysis) questions ask:

· Let's forget about the science content for a while. Could you accurately read some graphs and tables for a moment? Could you make some conclusions or extrapolations based on the information presented?


The Critical Analysis and Reasoning Skills (CARS) section of the MCAT tests three discrete families of textual reasoning skills; each of these families requires a higher level of reasoning than the last. Those three skills are as follows:

1. Foundations of Comprehension (30% of questions)

2. Reasoning Within the Text (30% of questions)

3. Reasoning Beyond the Text (40% of questions)

These three skills are tested through nine humanities- and social sciences—themed passages, with approximately 5 to 7 questions per passage. Let's take a more in-depth look into these three skills. Again, the bullet points of specific objectives for each of the CARS are taken directly from the Official Guide to the MCAT Exam; the descriptions of what these behaviors mean and sample question stems, however, are written by Kaplan.

Foundations of Comprehension

Questions in this skill will ask for basic facts and simple inferences about the passage; the questions themselves will be similar to those seen on reading comprehension sections of other standardized exams like the SAT® and ACT®. Foundations of Comprehension questions will require you to do the following:

· Understand the basic components of the text

· Infer meaning from rhetorical devices, word choice, and text structure

This admittedly covers a wide range of potential question types including Main Idea, Detail, Function, and Definition-in-Context questions, but finding the correct answer to all Foundations of Comprehension questions will follow from a basic understanding of the passage and the point of view of its author (and occasionally that of other voices in the passage).

Here are some sample Foundations of Comprehension question stems:

· Main Idea—The author's primary purpose in this passage is:

· Detail—Based on the information in the second paragraph, which of the following is the most accurate summary of the opinion held by Schubert's critics?

· (Scattered) Detail—According to the passage, which of the following is FALSE about literary reviews in the 1920s?

· Function—The author's discussion of the effect of socioeconomic status on social mobility primarily serves which of the following functions?

· Definition-in-Context—The word “obscure” (paragraph 3), when used in reference to the historian's actions, most nearly means:

Reasoning Within the Text

While Foundations of Comprehension questions will usually depend on interpreting a single piece of information in the passage or understanding the passage as a whole, Reasoning Within the Text questions will typically require you to infer unstated parts of arguments or bring together two disparate pieces of the passage. Reasoning Within the Text questions will require you to:

· Integrate different components of the text to increase comprehension

In other words, questions in this skill often ask either How do these two details relate to one another? or What else must be true that the author didn't say? The CARS section will also ask you to judge certain parts of the passage or even judge the author. These questions, which fall under the Reasoning Within the Text skill, can ask you to identify authorial bias, evaluate the credibility of cited sources, determine the logical soundness of an argument, or search for relevant evidence in the passage to support a given conclusion. In all, this category includes Inference and Strengthen—Weaken (Within the Passage) questions, as well as a smattering of related—but rare—question types.

Here are some sample Reasoning Within the Text question stems:

· Inference (Implication)—Which of the following phrases, as used in the passage, is most suggestive that the author has a personal bias toward narrative records of history?

· Inference (Assumption)—In putting together her argument in the passage, the author most likely assumes:

· Strengthen—Weaken (Within the Passage)—Which of the following facts is used in the passage as the most prominent piece of evidence in favor of the author's conclusions?

· Strengthen—Weaken (Within the Passage)—Based on the role it plays in the author's argument, The Possessed can be considered:

Reasoning Beyond the Text

The distinguishing factor of Reasoning Beyond the Text questions is in the title of the skill: the word Beyond. Questions that test this skill, which make up a larger share of the CARS section than questions from either of the other two skills, will always introduce a completely new situation that was not present in the passage itself; these questions will ask you to determine how one influences the other. Reasoning Beyond the Text questions will require you to:

· Apply or extrapolate ideas from the passage to new contexts

· Assess the impact of introducing new factors, information, or conditions to ideas from the passage

The Reasoning Beyond the Text skill is further divided into Apply and Strengthen—Weaken (Beyond the Passage) questions, and a few other rarely appearing question types.

Here are some sample Reasoning Beyond the Text question stems:

· Apply—If a document were located that demonstrated Berlioz intended to include a chorus of at least 700 in his Grande Messe des Mortes, how would the author likely respond?

· Apply—Which of the following is the best example of a “virtuous rebellion,” as it is defined in the passage?

· Strengthen—Weaken (Beyond the Text)—Suppose Jane Austen had written in a letter to her sister, “My strongest characters were those forced by circumstance to confront basic questions about the society in which they lived.” What relevance would this have to the passage?

· Strengthen—Weaken (Beyond the Text)—Which of the following sentences, if added to the end of the passage, would most WEAKEN the author's conclusions in the last paragraph?

CARS Summary

Through the Foundations of Comprehension skill, the CARS section tests many of the reading skills you have been building on since grade school, albeit in the context of very challenging doctorate-level passages. But through the two other skills (Reasoning Within the Text and Reasoning Beyond the Text), the MCAT demands that you understand the deep structure of passages and the arguments within them at a very advanced level. And, of course, all of this is tested under very tight timing restrictions: only 102 seconds per question—and that doesn't even include the time spent reading the passages.

Here's a quick reference guide to the three CARS skills:

Foundations of Comprehension questions ask:

· Did you understand the passage and its main ideas?

· What does the passage have to say about this particular detail?

Reasoning Within the Text questions ask:

· What must be true that the author did not say?

· What's the logical relationship between these two ideas from the passage?

· How well argued is the author's thesis?

Reasoning Beyond the Text questions ask:

· How does this principle from the passage apply to this new situation?

· How does this new piece of information influence the arguments in the passage?


Each of the four sections of the MCAT is scored between 118 and 132, with the median at 125. This means the total score ranges from 472 to 528, with the median at 500. Why such peculiar numbers? The AAMC stresses that this scale emphasizes the importance of the central portion of the score distribution, where most students score (around 125 per section, or 500 total), rather than putting undue focus on the high end of the scale.

Note that there is no wrong answer penalty on the MCAT, so you should select an answer for every question—even if it is only a guess.

The AAMC has released the 2017—2018 correlation between scaled score and percentile, as shown on the following page. It should be noted that the percentile scale is adjusted and renormalized over time and thus can shift slightly from year to year.

Total Score


Total Score




















































































































Source: AAMC. 2018. Summary of MCAT Total and Section Scores. Accessed January 2018.

Further information on score reporting is included at the end of the next section (see After Your Test).


We strongly encourage you to download the latest copy of MCAT® Essentials, available on the AAMC's website, to ensure that you have the latest information about registration and Test Day policies and procedures; this document is updated annually. A brief summary of some of the most important rules is provided here.

MCAT Registration

The only way to register for the MCAT is online. You can access AAMC's registration system at:

You will be able to access the site approximately six months before Test Day. The AAMC designates three registration “Zones”—Gold, Silver, and Bronze. Registering during the Gold Zone (from the opening of registration until approximately one month before Test Day) provides the most flexibility and lowest test fees. The Silver Zone runs until approximately two to three weeks before Test Day and has less flexibility and higher fees; the Bronze Zone runs until approximately one to two weeks before Test Day and has the least flexibility and highest fees.

Fees and the Fee Assistance Program (FAP)

Payment for test registration must be made by MasterCard or VISA. As described earlier, the fees for registering for the MCAT—as well as rescheduling the exam or changing your testing center—increase as one approaches Test Day. In addition, it is not uncommon for test centers to fill up well in advance of the registration deadline. For these reasons, we recommend identifying your preferred Test Day as soon as possible and registering. There are ancillary benefits to having a set Test Day, as well: when you know the date you're working toward, you'll study harder and are less likely to keep pushing back the exam. The AAMC offers a Fee Assistance Program (FAP) for students with financial hardship to help reduce the cost of taking the MCAT, as well as for the American Medical College Application Service (AMCAS®) application. Further information on the FAP can be found at:

Testing Security

On Test Day, you will be required to present a qualifying form of ID. Generally, a current driver's license or United States passport will be sufficient (consult the AAMC website for the full list of qualifying criteria). When registering, take care to spell your first and last names (middle names, suffixes, and prefixes are not required and will not be verified on Test Day) precisely the same as they appear on this ID; failure to provide this ID at the test center or differences in spelling between your registration and ID will be considered a “no-show,” and you will not receive a refund for the exam.

During Test Day registration other identity data collected may include: a digital palm vein scan, a Test Day photo, a digitization of your valid ID, and signatures. Some testing centers may use a metal detection wand to ensure that no prohibited items are brought into the testing room. Prohibited items include all electronic devices, including watches and timers, calculators, cell phones, and any and all forms of recording equipment; food, drinks (including water), and cigarettes or other smoking paraphernalia; hats and scarves (except for religious purposes); and books, notes, or other study materials. If you require a medical device, such as an insulin pump or pacemaker, you must apply for accommodated testing. During breaks, you are allowed to access food and drink, but not electronic devices, including cell phones.

Testing centers are under video surveillance and the AAMC does not take potential violations of testing security lightly. The bottom line: know the rules and don't break them.


Students with disabilities or medical conditions can apply for accommodated testing. Documentation of the disability or condition is required, and requests may take two months—or more—to be approved. For this reason, it is recommended that you begin the process of applying for accommodated testing as early as possible. More information on applying for accommodated testing can be found at:

After Your Test

When your MCAT is all over, no matter how you feel you did, be good to yourself when you leave the test center. Celebrate! Take a nap. Watch a movie. Ride your bike. Plan a trip. Call up all of your neglected friends or stalk them on Facebook. Totally consume a cheesesteak and drink dirty martinis at night (assuming you're over 21). Whatever you do, make sure that it has absolutely nothing to do with thinking too hard—you deserve some rest and relaxation.

Perhaps most importantly, do not discuss specific details about the test with anyone. For one, it is important to let go of the stress of Test Day, and reliving your exam only inhibits you from being able to do so. But more significantly, the Examinee Agreement you sign at the beginning of your exam specifically prohibits you from discussing or disclosing exam content. The AAMC is known to seek out individuals who violate this agreement and retains the right to prosecute these individuals at their discretion. This means that you should not, under any circumstances, discuss the exam in person or over the phone with other individuals—including us at Kaplan—or post information or questions about exam content to Facebook, Student Doctor Network, or other online social media. You are permitted to comment on your “general exam experience,” including how you felt about the exam overall or an individual section, but this is a fine line. In summary: if you're not certain whether you can discuss an aspect of the test or not, just don't do it! Do not let a silly Facebook post stop you from becoming the doctor you deserve to be.

Scores are released approximately one month after Test Day. The release is staggered during the afternoon and evening, ending at 5 p.m. Eastern. This means that not all examinees receive their scores at exactly the same time. Your score report will include a scaled score for each section between 118 and 132, as well as your total combined score between 472 and 528. These scores are given as confidence intervals. For each section, the confidence interval is approximately the given score ±1; for the total score, it is approximately the given score ±2. You will also be given the corresponding percentile rank for each of these section scores and the total score.


For further questions, contact the MCAT team at the Association of American Medical Colleges:

MCAT Resource Center

Association of American Medical Colleges

(202) 828-0690