Despite being one of the most memorization heavy sections that is often riddled with difficult figures, Biology and Biochemistry (B/B) can easily become one of your best MCAT scoring sections.
I received a score of 130 in the B/B section, scoring in the 96th percentile. Despite your experience with countless undergrad courses in anatomy, physiology, cellular biology, and biochemistry, this section may seem like endless content review, complex enzymatic pathways, convoluted figures, complicated graphs, among other obstacles. Fundamentally, this section tests your understanding of foundational concepts in biology and biochemistry, as well as your ability to apply these concepts in novel situations.
Start your journey with our introductory MCAT guide—everything you need to kick off your prep and ace the test!
What is the Biology and Biochemistry (B/B) Section of the MCAT?
The Bio/Biochem section of the MCAT is the third section of the MCAT, accounting for 25% of your overall score. There are 59 questions, formed from a combination of passage-based and discrete questions. The section takes 95 minutes to complete. This section is scored between 118 and 132.
This section evaluates your understanding of introductory concepts in biology, organic and inorganic chemistry, as well as biochemistry topics from first-semester college courses. It also tests cellular and molecular biology knowledge from introductory biology and biochemistry classes, alongside basic research methods and statistics. Additionally, this section requires you to demonstrate scientific inquiry, reasoning, and the application of research methods and statistical skills in the natural sciences.
The breakdown is as follows:
- First-semester biochemistry, 25%
- Introductory biology, 65%
- General chemistry, 5%
- Organic chemistry, 5%
The section will include the following topics:
- Biomolecules and their roles in cell structure, function, and life-sustaining processes.
- Interactions among molecules, cells, and organs that enable living organisms to function.
- The complex systems of tissues and organs that sense and respond to internal and external environments to maintain stability within changing conditions.
Tips and Tricks to Acing the MCAT Biology/Biochemistry Section
#1. Start studying early and utilize practice questions and practice tests.
The Biology/Biochemistry section had the greatest amount of content to review, with many different concepts spanning from micro (DNA, cells, etc) to macro scale (anatomy, physiology, organ systems etc) . Regular practice will help you realize the key terms that you still are struggling to recall. Focus your review on weaker content.
#2. No content is low-yield, however there are “must know topics”.
You should review content as though ALL material matters and can be tested, especially as discrete questions.
There are topics that historically to seem to be important and consistent between all MCAT tests. More likely than not, you will come across questions that require mastery of all the amino acids (abbreviations, structure, properties), major metabolic pathways (glycolysis, Krebs cycle, fermentation, gluconeogenesis, ATP synthesis, glycogenesis, glycogenolysis, fatty acid synthesis, beta-oxidation, pentose phosphate pathway), experimental techniques (PCR, western blot, southern blot, northern blot, gel electrophoresis) as well as major organ systems (nervous, endocrine, cardiac, renal). The method that you use to either review or learn new content is dependent on your own study strategies (note taking, Anki, etc), however it is important to be always employing active recall.
I personally did not use Anki while studying for the MCAT, but I would likely use Anki to learn content if I were to rewrite today. I created notes and forced myself to actively recall the information of small topics to ensure I had a grasp of the material I was reading. Anki forces you to use active recall by nature of the program. Whichever method you use, an excellent benchmark for having mastery of the material is feeling comfortable teaching one of your peers the content from memory, in a clear and concise manner.
#3. Use acronyms or mnemonics.
There are so many concepts and details to memorize in the biology/biochemistry section, so use acronyms and mnemonics to your advantage. These are readily found online in forum posts; however I’ve also linked a useful page here.
For example, the different kinds of biochemistry blots may be difficult, but using the pneumonic “SNOW DROP” to remember that a Southern blot is used to study DNA, Northern blot is used to study RNA, and Western blot is used to study proteins, is much more digestible.
Memorizing the tricyclic acid intermediates can be difficult, so use the pneumonic “Can I Keep Selling Sex for Money Officer?”, to represent citrate, isocitrate, alpha-ketoglutarate, succinyl-CoA, succinate, fumarate, and oxaloacetate.
To remember the anterior pituitary hormones, just remember “FLAT PEG”, representing follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), thyroid stimulating hormone (TSH), prolactin, endorphins, and growth hormone (GH).
These are just some commonly utilized acronyms and mnemonics. There are many more, so use them to your advantage and streamline your content reviewing.
#4. Try to predict answers.
Do attempt to try to predict what an answer will be as you are reading a question BEFORE you read answer choices. While practicing, this will help with “active recall” and demonstrate a deeper understanding of content, rather than only being able to “recognize an answer” which shows only a superficial understanding.
When you attempt to predict and have a sense of what the correct answer may be, you will likely be able to eliminate answer choices that are evidently different from your initial thought. This method is great for all practice, but your mileage may vary for the actual MCAT, so decide whether this is a strategy that will be a cornerstone for your MCAT approach.
#5. Understand graphs/figures. Practice identifying the independent, dependent, and control variables. Focus on the significant findings of each graph.
If interpreting the results of graphs of figures is difficult, my advice is to practice identifying and noting the key result of any experiment. Determine what the researchers are intentionally changing (the independent variable), what they are measuring as an outcome (the dependent variable), and what must be kept constant to ensure valid results (the controls) until it becomes second nature. Note the title, axes labels, or any statistically significant results that are indicated. Use all this to guide what the figure is ultimately trying to convey—take notes and make simple flow diagrams.
#6. Eliminate wrong answers.
There inevitably will be questions that you cannot figure out the correct answer. It may seem obvious but start by crossing out choices that you are confident are wrong. If you ultimately must guess, you have at least significantly improved your chances of guessing correctly.
MCAT Biology Passage Example: Strategies to Get the Right Answer
In the 2nd paragraph, we see that bacteria in the gut microbiota catabolize fibre resulting in short chain fatty acids (SCFAs), which then can activate GCPRs. In simpler terms, the presence of a gut microbiome allows for SCFAs to be produced which activate GCPRs.
Applying Tip #5, we will break down figure 1 into simpler terms. We know there are two germ lines of mice: wild type (no gene mutations) and Gpcr43-/- (lacking GPCR43 gene). In this experiment, each of these mouse lines are fed either a standard diet (Std) or high-fat diet (HFD), resulting in our four groups reflected in the figure. We see that mice which are fed the HFD have higher body weights, and that the Gpcr43-/- mice have higher body weights compared to WT. In simpler terms, we know that that being fed a HFD results in higher body weight, and that losing the GPCR43 gene results in higher body weight.
The question asks us how these germ lines would be affected if a mouse is raised in a conventional environment (gut microbiome present), or germ-free environment (no gut microbiome). At this point, we apply Tip #4 and attempt to make a prediction: Gpcr43-/- mice should have higher weights than WT in a conventional environment, based on our interpretation of Figure 1. Applying Tip #6, we can eliminate options A and D, as Gcpr43-/- have less body weight that its WT counterparts, which is unexpected.
We can predict that in a germ-free environment without a gut microbiome, SCFAs cannot activate GCPRs, and we know that losing the function of the GCPR gene results in higher body weight. Between B and C, we know C is incorrect as a WT mouse that grows up in a germ-free environment (losing the ability to produce SCFAs that activates the GCPR43 gene) effectively functions as a GCPR43-/- mouse line, meaning its body weight should be higher than the conventional group, however this is not the case in choice C. This finding is reflected in option B, the correct answer.
Need some additional tips? Check out our tips for acing the Chemistry/Physics, CARS, and Psychology/Sociology sections.
Final Thoughts
I know that biology/biochemistry can often be overwhelming with the sheer amount of content, complex pathways, and convoluted figures. However, consistent practice with the correct study and testing strategy outlined in this guide will create opportunities for excelling in the biology and biochemistry section of the MCAT and achieving your dream score. By mastering the foundational concepts, practicing regularly, using acronyms/mnemonics, and learning effective test taking strategies, you can maximize your performance on test day and become one step closer to achieving your goals. I have faith, you got this!
