As someone who's finished the bio course second in his cohort - you only really need to know a few key terms. Stuff like ecosystem dynamics isn't really covered, as long as you know the foundational stuff (ie osmosis, diffusion, organelles and their function), you'll be fine :3
If it's unconditional (not on the basis of acquiring a specific ATAR) you'll be fine. Just make sure you pass your exams as you still need them to acquire your Higher School Certificate and enrol in uni :)