This is the "Bible" of the Olympiad. You should not just read it; you should know the diagrams and experimental sections inside out.
Finding a "full" archive can be challenging as some years are kept under wraps for training purposes. However, these are the most reliable sources: singapore biology olympiad past papers full
SBO questions are notoriously "wordy." Practicing past papers helps you filter out "noise" and identify the core biological concept being tested. This is the "Bible" of the Olympiad
Essential for the plant anatomy sections which are often a stumbling block for Singaporean students. However, these are the most reliable sources: SBO
Mastering the Singapore Biology Olympiad: A Guide to Past Papers and Preparation
Since the SBO is modeled after the International Biology Olympiad, the IBO past papers are the best substitute. They follow the same rigorous standard and cover identical themes.
Multiple-true-false (where you must evaluate four statements for every question). 2. The Practical Round