USABO and BBO are widely recognized as the leading international biology competitions for high school students. They are highly respected credentials for applications to top universities in the UK and US for biology, medicine, biochemistry, and related programs. This guide covers the key rules, award structures, and preparation strategies for both competitions in the 2027 season.
USABO — USA Biology Olympiad (China Region: BIO-USACN)
The USABO is organized by the Center for Excellence in Education (CEE), which selects and trains the US team for the International Biology Olympiad (IBO). In China, it runs as BIO-USACN under ASDAN, part of the BioOlympiad Initiative USA-China (BIOUS). It uses the same English questions as the US Open Exam and is one of the most academically demanding STEM competitions available to high school students.
Value: A direct pathway credential for Ivy League and Top 20 university applications in biology-related majors. Can be listed under Honors on the Common App. The IBO 2026 competition takes place in Vilnius, Lithuania, July 12–19, 2026, with the US four-student team representing USABO finalists.
Target Students: Grades 9–12 aiming for biology, medicine, biochemistry, or neuroscience programs in the US or UK. Ideal for students with a solid English and biology foundation who seek academic depth and prestige.
Competition Rules and Exam Content
2027 Season: The 2026 China exam was held on April 4, 2026 — the season is now complete. The 2027 China region exam date will be announced later in 2026. Begin preparation now to build the strongest possible foundation.
Format: Individual written exam, entirely in English. 50 multiple-choice questions in 50 minutes. Available online or offline. No laboratory component at the Open Exam level.
Scoring: 1 point per question, maximum 50. No penalty for incorrect or unanswered questions.
Exam Content: Animal Anatomy and Physiology, Cell Biology, Genetics and Evolution, Plant Anatomy and Physiology, Ecology, Animal Behavior, Biosystematics, Bioinformatics.
China Region Award Tiers:
- Top Gold Medal: Top 5% nationally
- Gold Medal: Top 15% — recent raw cutoff approximately 40/50
- Silver Medal: Top 30% — recent raw cutoff approximately 33/50
- Bronze Medal: Top 45% — recent raw cutoff approximately 25/50
BBO — British Biology Olympiad
The BBO is hosted by the Royal Society of Biology, with questions set by professors from Oxford and Cambridge. Running since 1995, it is one of the longest-running and most respected high school science competitions in the UK, serving as the primary selection process for the UK IBO team. A BBO Gold medal is a standard expectation for competitive applicants to biology programs at UK G5 universities.
Value: Heavily emphasized in UCL, Imperial College London, and Oxford interviews. The global award rate is approximately 35% for top tiers. Imperial College London’s Biological Sciences admitted cohorts consistently show high rates of BBO Gold holders.
Target Students: Grades 9–12 aiming for biology-related programs in the UK or US. Ideal for students with strong English reading skills, information-processing ability, and those who benefit from a higher award rate relative to USABO.
Competition Rules and Exam Content
2027 Season: The BBO 2027 exam is expected in January 2027 (reference date based on past cycles).
Format: Individual written exam. In the China region, a Chinese-English bilingual version is provided. The number of questions increases annually (up to 297 in recent years). Question types include single-choice, multiple-choice, fill-in-the-blank, true/false, and chart/data analysis. Duration: 90 minutes.
Scoring: 1 point per question. No penalty for incorrect or unanswered questions.
Exam Content: Animal Anatomy and Physiology, Cell Biology, Genetics and Evolution, Plant Anatomy and Physiology, Ecology, Animal Behavior, Biosystematics.
Award Tiers:
- Gold Medal: Top 5%
- Silver Medal: Top 15%
- Bronze Medal: Top 30%
- Excellence Award: Top 45%
- Commendation Award: Top 60%
Choosing Between USABO and BBO
- Applying to Both US and UK Universities (Recommended): Register for both. The syllabi overlap by approximately 90%. A single preparation effort yields credentials recognized at top universities in both countries.
- Targeting US Universities or Seeking Academic Depth: Prioritize USABO (BIO-USACN). Best for students with a strong biology foundation, excellent English, and logical reasoning skills. A Gold Medal demonstrates strong academic capability.
- Targeting UK Universities or Seeking a Higher Award Rate: Prioritize BBO. The bilingual format reduces the language barrier, and the overall award rate is higher than USABO. Suited to students with strong comprehensive knowledge and information-processing skills.
- Grades 9–10: Start with BBO to build a strong foundation. In Grade 11, transition to adding USABO for a higher-prestige award targeting the 2027 season.
Preparation Approach for the 2027 Season
Preparation for both exams should be structured around the specific characteristics, core topics, and format demands of each competition. The most effective approach combines systematic content mastery with regular timed past-paper practice.
Key content areas shared by both exams: cell biology, genetics and evolution, animal anatomy and physiology, plant anatomy and physiology, and ecology. Students can use Campbell Biology as the primary foundation text for both. USABO requires additional depth in molecular mechanisms, signaling pathways, and bioinformatics. BBO requires broader coverage of taxonomy and animal behavior, plus explicit time-management practice given the high question volume.
The 2026 exam season is complete. Students targeting the 2027 season should use the current period to begin systematic study, building the strong knowledge base needed to compete for Gold-level awards.