Where the points actually are

USABO tests well beyond an ordinary high school biology course, and the single most effective preparation is working through Campbell Biology carefully rather than doing more practice questions. Students who place typically know the molecular and physiology chapters at a level closer to a first-year university course.

Topic breakdown

01Cell and molecular biology: The largest slice of the exam. Membrane transport, signalling, respiration, photosynthesis, the cell cycle, and molecular genetics in detail.
02Genetics and evolution: Mendelian and population genetics, linkage, gene regulation, phylogenetics, and quantitative problems on allele frequencies.
03Anatomy and physiology: Animal systems in depth, particularly nervous, endocrine, circulatory and renal, plus plant structure and transport.
04Ecology and behaviour: Population dynamics, community interactions, biogeochemical cycles, and animal behaviour.
05Data interpretation: Many questions present an unfamiliar experiment and ask what it shows. This is a skill, and it is practised rather than memorised.

A study plan that works backwards from the date

Summer before Read Campbell Biology properly, a few chapters a week, taking notes. This is the standard text the exam content tracks.
Autumn Work through past Open Exams, which are published free on the USABO site. Mark ruthlessly and go back to the textbook for every miss.
Winter Focus on your weakest system. Most students have one area, often plant physiology or population genetics, that is costing disproportionate points.
After the Open Exam If you advance, shift to free response practice and to the International Biology Olympiad past papers, which are harder and published openly.

Tips that come from the format itself

Past Open and Semifinal exams are published free by USABO and are the most accurate guide to difficulty and style.
International Biology Olympiad past papers are also free online and are excellent preparation for the semifinal round.
Do not neglect plants. Plant physiology is consistently underprepared by United States students relative to its weight.
Register your school early. Every year students discover in January that their school never registered.

Practice resources

USABO official site (also: campbell biology) Official · free
Registration, exam dates, rules and free past exams. The standard reference text the exam content tracks. Any recent edition works.
International Biology Olympiad past papers Past problems · free
Free past papers from the international competition, harder than USABO but excellent semifinal preparation.

Past papers and official materials

USABO past Open and Semifinal exams
Published free by the Center for Excellence in Education.

Skills this builds

Read what other students said about preparing