Hello!

if you’re done with IB Bio HL, it is definitely possible for you to take the AP Bio exam.

But, i advise you to finish the HL curriculum before trying to prepare for AP.

The IB curriculum tends to be much more strict and in depth, so you wouldn’t have to relearn that much.

The only problem is, the IB problems tend to be much more straightforward compared to the AP Bio exam

so you have to be able to think on your feet about topics that you may have not learned.

Moreover, there aren’t a lot of practice exams that are available to students who are self studying for the AP exam, so you’ll need to take as many practice exams as you can to be well prepared. 

Talk to your school teacher and see if he/she may be able to get some resources available to teachers.

and ask me questions here! ill try to help you as much as possible. 

good luck with your studies!! :D