year 11 exams: i have 3 weeks and i havent started studying

I know the exams don't actually matter at all, especially because I've already gotten my S for my units. But I want to treat these exams as I would in year 12, which is honestly off to a rough start due to a mysterious illness I suddenly got upon returning to school for term 4.

I am kinda worried about biology because there is HEAPS of content, across the whole year. I'm just wondering if there's any way to spread subjects like this out, and study everything without like reading the entire textbook again.

Like how do I tackle all this work, how do I even start. I've prepared all my summary notes for each chapter but I feel so lost.

I'm just wondering how you guys revise. I know three weeks isn't too late because there's still time, I just wanna do well in these ones so I have the confidence for year 12.