How many questions is the MCAT Bio/Biochem section and how much time do I get?

59 questions in 95 minutes — 44 tied to 10 passages and 15 standalone. That averages just over a minute and a half per question, which is why passage triage and not re-reading figures is part of the coaching.

Do I need to have taken biochemistry before starting?

It helps considerably, since roughly 25% of the section is biochemistry. If you haven't taken it, sessions can build amino acid properties, enzyme kinetics, and the major metabolic pathways directly, but expect that to take a meaningful share of your prep time.

Do I have to memorise all 20 amino acid structures?

Yes, including three- and one-letter codes, side-chain polarity, and the pKa ranges for the ionisable ones. Questions on net charge at a given pH, isoelectric focusing, and which residue sits in an enzyme active site all assume you can picture the structure without a chart.

My content knowledge is fine but my score isn't moving — what's going on?

That pattern usually means the errors are in passage interpretation, not recall: answering from memory when the data contradict it, or choosing an option that goes further than the experiment supports. Sessions target this by having you justify eliminations aloud on your own missed questions.

MCAT Bio/Biochem

Graduate Tests · Test Prep

The Biological and Biochemical Foundations of Living Systems section gives you 59 questions in 95 minutes: 10 passage sets plus 15 standalone questions. Roughly a quarter of it is biochemistry, most of the rest is introductory biology, with a handful of items drawing on general and organic chemistry. Nearly every passage is built around an experiment — a knockout mouse, a kinetics assay, a gel — so the work is less about recalling pathways than about reading data through the lens of pathways you already know. These sessions run as spoken back-and-forth: you talk through a stem, get pushed on the reasoning, and get corrected in the moment rather than reading an explanation afterwards.

Start a session on MCAT Bio/Biochem

What this covers

Amino acid structures, side-chain pKa values, and predicting net charge, isoelectric point, and titration curve behaviour at a stated pH
Enzyme kinetics and regulation: Km and Vmax, competitive vs. noncompetitive vs. uncompetitive inhibition, allosteric control, and reading Lineweaver-Burk and Michaelis-Menten plots
Metabolic pathway logic — glycolysis, PDH, TCA, oxidative phosphorylation, glycogen handling, fatty acid oxidation — with emphasis on rate-limiting steps, hormonal control, and fed vs. fasted state
Molecular biology techniques as they appear in passages: PCR, Western and Southern blotting, ELISA, gel electrophoresis, CRISPR and knockouts, reporter assays, and what a given control rules out
Organ system physiology with a functional emphasis: nephron transport, cardiac and respiratory mechanics, endocrine feedback axes, and immune cell roles
Experimental passage strategy — identifying the hypothesis, matching the answer to the figure axes, and eliminating choices that overstate what the data show

Where learners get stuck

Treating uncompetitive and noncompetitive inhibition as interchangeable, or misreading which one moves Km on a double-reciprocal plot: Coursework often teaches only competitive and 'everything else.' Because uncompetitive inhibition lowers both Km and Vmax, students who memorised 'inhibitors raise Km' pick the wrong graph, and the MCAT tests exactly this distinction.
Memorising glycolysis step by step but freezing when a passage asks what happens to flux when insulin rises or when a specific enzyme is knocked out: Pathways are usually learned as linear lists rather than as regulated systems. The exam almost never asks for step 6; it asks which metabolite accumulates and what the cell does next, which requires knowing the irreversible control points and their hormonal signals.
Answering physiology questions with textbook facts that contradict the passage's own data: Under time pressure, recall is faster than reading. But many Bio/Biochem passages describe a mutant, a drug, or a non-human model where the standard answer is wrong on purpose, and the correct choice follows from the figure, not from first-year biology.

What a session looks like

A typical session starts with two or three minutes of retrieval on something from last time — naming the charged amino acids, or the steps insulin activates. Then you work a passage aloud: you summarise the experimental setup and what each figure axis measures before touching the questions, and you say why each wrong option is wrong, not just why one is right. Where you stall, the tutor stops and rebuilds the underlying concept — often by having you sketch or verbally trace a pathway or a feedback loop — then returns to the question. Sessions end with a named list of the specific gaps that showed up, so the next one starts there.

Helpful to know first

Two semesters of introductory biology, including genetics, cell biology, and organ system physiology
At least one semester of biochemistry, or willingness to build amino acids, enzyme kinetics, and core metabolism from scratch during sessions
General chemistry through acid-base and equilibrium, since pKa reasoning appears throughout the biochem questions
Basic organic chemistry familiarity with functional groups and nucleophilic attack, enough to follow a proposed enzyme mechanism
A source of full-length practice material, since sessions review your own performance rather than supplying an official question bank

Questions

How many questions is the MCAT Bio/Biochem section and how much time do I get?: 59 questions in 95 minutes — 44 tied to 10 passages and 15 standalone. That averages just over a minute and a half per question, which is why passage triage and not re-reading figures is part of the coaching.
Do I need to have taken biochemistry before starting?: It helps considerably, since roughly 25% of the section is biochemistry. If you haven't taken it, sessions can build amino acid properties, enzyme kinetics, and the major metabolic pathways directly, but expect that to take a meaningful share of your prep time.
Do I have to memorise all 20 amino acid structures?: Yes, including three- and one-letter codes, side-chain polarity, and the pKa ranges for the ionisable ones. Questions on net charge at a given pH, isoelectric focusing, and which residue sits in an enzyme active site all assume you can picture the structure without a chart.
My content knowledge is fine but my score isn't moving — what's going on?: That pattern usually means the errors are in passage interpretation, not recall: answering from memory when the data contradict it, or choosing an option that goes further than the experiment supports. Sessions target this by having you justify eliminations aloud on your own missed questions.