After reading the problems again, well, I might have to take my words back. When I said basic biology, it's not high-school biology, but college-level biology. There are five main topics: molecular cell biology, anatomy and physiology of animals, anatomy and physiology of plants, genetics, and ecology. If you want to get a medal in the international competition, then, you probably need to read the text book material for each topic to get the basic concepts.
For example, for molecular cell biology, you need to know about electrophoresis. My point was, in the exam, you won't be asked about what is electrophoresis. They will give you an example of an experiment/published paper, give you the background of that experiment, give you the experiment results (including electrophoresis results), and then ask you about the conclusion of the experiment.
I don't understand why they protect the past exams with a password[0], but here's one sample question from my archive: https://i.imgur.com/nMW7g9b.jpg
Feel free to reach out to me via email if you want to discuss more.
[0] https://www.ibo-info.org/en/info/papers.html