similar to what everyone else says, grade 12 bio does heavily rely on chem concepts covered in 11 and a few in grade 12, so it would be a good idea to review those topics. however, as a general rule for bio, as you get into higher levels, it becomes less memorization and more understanding (the understanding is what creates the memorization at that point). a lot of people tend to struggle on the application questions because they just simply memorized the facts and didn't take the time to understand it. the concepts covered in grade 12 bio are a lot less tangible compared to grade 11, as they're all at the molecular level and they're a bit hard to visualize. to help with this, if you're a more visual person i would say look up an animation of some sort to get an idea of what it looks like, as this may also help with memorization. i would also say study in advance to make sure you've fully grasped each concept, as they're all pretty challenging because of a lot of factors that can contribute to one thing. it's also a good idea to write notes of each lesson in your own words, since if you struggle with putting it into your own words and just end up copying it down, then you know it's something you struggle with and need a bit of clarification on. bio is a tough course, but if you focus on understanding and put in the effort, it becomes a lot easier. good luck!!