Here is a list of resources I have compiled (I plan on studying these over the summer), please let me know if you have any additional resources.
IBO syllabus (and past problem sets)
AP chem - enzyme kinetics, and spectrophotometric assays
Raven’s Biology
Campbell Biology
Vander’s Physiology
Raven’s Plant
AP Statistics
Alberts Molecular Biology of the Cell first half
Life - William S. Beck
Lehningher’s Biochemistry
All previous biology olympiads
An Introduction to Behavioural Ecology
Introduction to Genetic Analysis (First 4 chapters plus chapters on proteins enzymes, sugars, lipids, and nucleic acids)
Klug’s Genetics
BRS Physiology