AP exams, 8 units
AP Biology exam guide
Study all eight AP Biology units against the College Board framework, from the chemistry of life through ecology.
Follows the fall 2025 course and exam description, from 4 May 2026
Overview
What AP Biology covers.
AP Biology is a full-year, college-level introductory biology course built around four big ideas: evolution, energetics, information storage and transmission, and systems interactions. The Course and Exam Description organizes that content into eight units, each carrying a published weighting range on the multiple-choice section, and pairs it with six science practices that the free-response questions assess directly.
Because the weightings are published as ranges, proportional study planning works well here. Natural selection and the two energy-and-information units (cellular energetics and gene expression) together account for a large share of the exam, while the laboratory-derived skills of experimental design, data analysis, and statistical reasoning cut across every unit. The free-response section rewards students who can justify a claim with evidence rather than recite a definition.
Arcade Academy is an independent study workspace. Use the official Course and Exam Description as the authoritative statement of what is on the exam, and treat the unit pages below as a way to organize review, spaced repetition, and practice.
At a glance
- Total time
- 3 hours
- Section I
- 60 multiple-choice questions in 1 hour 30 minutes, 50% of the exam score
- Section II
- 6 free-response questions in 1 hour 30 minutes, 50% of the exam score: 2 long questions worth 9 points each and 4 short questions worth 4 points each
- Delivery
- Hybrid digital: multiple-choice questions are answered and free-response prompts are read in College Board's Bluebook app, and free-response answers are handwritten in a paper booklet
- Calculator
- Permitted on the exam; a reference sheet with formulas and statistical tables is provided
- Score scale
- 1 to 5
- Governing body
- College Board
- Who takes it
- High school students taking AP Biology for college credit, placement, or a stronger transcript in the life sciences.
Scoring
Raw points from the multiple-choice and free-response sections are combined into a composite score, which College Board converts to the reported 1 to 5 scale using cut points set for that year's exam. Credit and placement policies are set independently by each college, so the same score can mean different things at different institutions.
Exam structure
Units
AP Biology covers 8 units. Open one for its topics, published weighting, and section-specific study tips.
Unit 1: Chemistry of Life
8–11%Unit 1 establishes the chemical foundation the rest of the course depends on: why water behaves the way it does, which elements…
6 topics
Unit 2: Cell Structure and Function
10–13%Unit 2 covers subcellular components and their jobs, the surface-area-to-volume constraint on cell size, and everything that…
6 topics
Unit 3: Cellular Energetics
12–16%Unit 3 begins with enzymes as the controllers of reaction rate, then moves through photosynthesis and cellular respiration as…
6 topics
Unit 4: Cell Communication and Cell Cycle
10–15%Unit 4 links signaling to control: how cells send and receive signals, how a signal is transduced and amplified inside the cell…
6 topics
Unit 5: Heredity
8–11%Unit 5 covers meiosis as the source of genetic variation and the inheritance patterns that follow from it. Mendelian ratios, sex…
6 topics
Unit 6: Gene Expression and Regulation
12–16%Unit 6 follows information from DNA through RNA to protein and then asks how that flow is controlled. Replication, transcription…
6 topics
Unit 7: Natural Selection
13–20%Unit 7 carries the widest weighting range in the course. It covers the mechanisms of evolutionary change, population genetics and…
7 topics
Unit 8: Ecology
10–15%Unit 8 scales up from individuals to populations, communities, and ecosystems. It covers behavioral and physiological responses…
6 topics
Study strategies
How to work through this exam.
These strategies follow from the exam's own structure. Adapt them to the time you actually have each week.
- Allocate review time roughly in proportion to the published unit weightings, giving the widest ranges (natural selection, cellular energetics, and gene expression) the most sessions.
- Practice the science practices explicitly, not just the content: analyzing a graph, designing an experiment with a stated control, and justifying a claim with evidence are what the free-response section scores.
- Work the quantitative skills on a schedule, since chi-square, Hardy-Weinberg, and water potential appear every year and decay quickly without practice.
- Write full free-response answers under a timer rather than outlining them; the scoring rubrics reward complete reasoning chains, and pacing is a separate skill from knowing the biology.
- Use spaced repetition for the vocabulary-dense material (organelles, macromolecules, pathway locations) so review time can shift toward reasoning as the exam approaches.
- Review released free-response questions and their scoring guidelines to see how points are actually awarded before you write many practice answers.
Common questions
AP Biology questions students ask.
How is the AP Biology Exam structured?
The exam runs 3 hours. Section I is 60 multiple-choice questions in 1 hour 30 minutes for 50% of the score, and Section II is 6 free-response questions in 1 hour 30 minutes for the other 50%, made up of 2 long questions worth 9 points each and 4 short questions worth 4 points each.
Which AP Biology units are hardest?
College Board does not rank unit difficulty. In practice, students most often report trouble with the quantitative reasoning in Unit 7 (Hardy-Weinberg and phylogenies), the pathway detail in Unit 3, and the multi-step regulation questions in Units 4 and 6. Your own practice results are a better guide than any general ranking.
How is the AP Biology Exam scored?
Points from both sections are combined into a composite score that is converted to the reported 1 to 5 scale, with cut points set each year. Colleges set their own credit and placement rules, so no score guarantees credit at a particular school.
When should I start studying for the exam?
A common approach is to review each unit as the class finishes it, then start cumulative practice and timed free-response work roughly two to three months before the May exam. Starting earlier mostly helps by letting spaced repetition intervals stretch out before exam week.
Can I use a calculator, and is the exam on paper or a computer?
Calculators are permitted, and a reference sheet with formulas and statistical tables is provided. AP Biology is a hybrid digital exam: multiple-choice questions are answered and free-response prompts read in College Board's Bluebook app, while free-response answers are handwritten in a paper booklet. Confirm current policy on the official exam page before test day.
Is Arcade Academy affiliated with College Board?
No. AP® is a registered trademark of College Board, which was not involved in the production of, and does not endorse, this site. Arcade Academy is an independent educational resource; use College Board publications as the authoritative source on the course and exam.
Before you build the schedule
Exam structures change. Confirm the current format, eligibility, and policies with College Board before you commit to a study plan.
Official exam information opens in a new tabGuide structure last checked against official sources on August 30, 2026.
Markdown version of this guide for citation, offline reading, and language models.
Study AP Biology with a plan you can keep.
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