The Ultimate MCAT B/B Study Guide (Biology & Biochemistry)- Ion Prep

The MCAT Biology and Biochemistry (B/B) section is often considered one of the most content-heavy sections of the exam. While many students assume it’s “just memorization,” high scorers know that success in B/B comes from understanding systems, experimental logic, and data interpretation. This MCAT B/B study guide breaks down exactly how to study efficiently and score higher.

What’s Tested in MCAT B/B?

The B/B section focuses on high-yield topics like:

• Cellular and molecular biology- Cell Membrane, Cell Transport, Cell Signalling

• Biochemistry- Enzyme Kinetics, Amino Acid Chemistry, Metabolic Pathways

• Genetics and molecular biology- DNA Replication, Cell Cycle, Mitosis/Meiosis

• Organ systems and physiology- Endocrine and Nervous System, Reproductive System

• Experimental design and data analysis- Biochemistry Lab Techniques, the concept of knockout genes, LOF (loss of function allele), GOF (gain of function allele), simply knowing how to interpret a scientific paper

Most B/B questions are passage-based, so just memorizing the content will not work for this section.

1) Master High-Yield Biology Concepts

Focus on core themes that appear repeatedly:

• Enzyme kinetics and inhibition

• DNA replication, transcription, and translation

• Cell signaling pathways

• Membrane transport

• Metabolism (glycolysis, TCA, ETC)

• Organ system integration

Instead of memorizing facts, ask:

What happens if this step fails? What changes upstream or downstream?

The MCAT is mostly application, so memorizing WILL NOT work here! Your approach should emphasize UNDERSTANDING the role of these pathways and organ systems in the mammalian body.

2) Biochemistry = Relationships, Not Reactions

For MCAT biochemistry:

• Understand why pathways exist

• Know rate-limiting steps

• Identify energy inputs and outputs

• Track carbon flow and redox changes

  If possible, try also to make connections with various types of Organic Chem reactions that are likely to be tested. Much of the information from testable Orgo Chem material and Biochem material overlap, so try to make connections from both ends.

• Example: The fourth step of glycolysis is catalyzed by the enzyme aldolase, which cleaves a six carbon fructose-1,6-bisphosphate into G3P and DHAP. This is also an example of a retro-aldol cleavage reaction (opposite of an aldol condensation), which is testable in MCAT Orgo!

3) Learn to Read MCAT-Style Passages

MCAT B/B passages often include:

• Experimental setups

• Mutant vs wild-type comparisons

• Graphs and tables

• Research conclusions

Train yourself to:

• Identify the research question

• Recognize independent vs dependent variables

• Predict outcomes before reading the answer choices

4) Practice with Purpose

When reviewing practice questions:

• Identify why wrong answers are wrong

• Look for recurring traps

• Track weaknesses by topic, not test date

The MCAT B/B section rewards critical thinking, integration, and logic. You need to make sure you understand your strengths and weaknesses in this section, as well as practice questions that target your weaknesses. Ion Prep can help with identifying your weaknesses and building an effective B/B study plan. Contact us for a free 15 min consultation today!