Hey there
The biggest fact that needs to be glorified is that studying by heart only for 3 or 4 times can make you remember entire book lifelong.
Make sure that you study when you feel like doing it. Studying without mind concentration is a mere waste of time and efforts.
Especially, subjects like biology, which require ultra high concentration levels can be thoroughly gained by reading, understanding and practicing for a few times only.
So, get to work.
All the best.