AP Biology review: exam format, the 8 units, and how to study

What’s on the AP Biology exam

The AP Biology exam splits evenly into two sections. Section I is 60 multiple-choice questions in 90 minutes, worth 50%, and many come in sets built on data, graphs, and experiments. Section II is 6 free-response questions in 90 minutes, also 50%: two long questions worth more points and four short questions, covering interpreting data, designing experiments, and explaining biological processes.

A four-function, scientific, or graphing calculator is allowed on both sections, and you are given a formula sheet with the key statistics equations — so the exam rewards reasoning and data analysis, not memorizing numbers. The whole thing runs 3 hours and is a hybrid format: the multiple choice is in the Bluebook app while the free response is handwritten.

The 8 units of AP Biology

AP Biology is organized into eight units that build from molecules to ecosystems. Natural selection is the most heavily tested, and energetics and gene expression are close behind.

How AP Biology is scored

Your multiple-choice and free-response points are combined into one composite score, which the College Board scales to a 1–5 each year. AP Biology is a fairly passable exam — recent years have seen roughly two-thirds of students earn a 3 or higher — but a 5 rewards students who can analyze data and explain mechanisms clearly on the free response.

To see what a practice raw score turns into, run it through our AP Biology score calculator.

How to study for AP Biology

Lead with understanding, not memorization. The exam asks you to explain processes, interpret experiments, and apply concepts to new scenarios, so build your review around how and why things happen — energy flow, gene expression, natural selection — rather than isolated facts.

Then practice the free response heavily, since it is half the exam and rewards clear, evidence-based reasoning. Work past questions against the rubric with our AP Biology FRQ guide, drill one unit at a time using the Progress Check walkthroughs, and brush up the high-yield ideas with our AP Biology concepts.

When is the AP Biology exam, and how long is it

AP Biology is given once a year during the College Board’s May testing window, and the exam takes 3 hours. The exact date and start time are set each year, so confirm the current schedule on the official AP calendar with your coordinator before you plan around it.