The paper is less about content and more about skills/having a super firm grasp on the fundamentals
eg. They might ask you why animals in colder climates have short stocky limbs. You may think, what the hell, I've never even studied this, but if you know your basics, then you can figure out that in colder climates, animals want to conserve heat thus they want to minimise their surface area:volume ratio.
If you're genuinely interested in bio, you'll do great. Just watch extra videos on youtube when you're in the mood. The topics for bio olympiad are so broad that anything will help for it.
All the questions in the paper give you all the information you need to answer it, so if you knew the basics well enough, you'd be able to just show up knowing minimal content and do super well.
Good luck
What can I do to at least get Distinction?