How to revise GCSE Biology? Watch
Here are a few revision websites:
Physics and Maths Tutor
I find doing exam questions really useful because lots of marks in biology are awarded for mentioning certain things - so practice questions help you to learn how to answer exam questions properly.
Before any biology test I write a summary of the topic across a few pages the night before. Idk if this will work for you but it just means all the information is fresh in my mind for the test. It also means I have more revision resources when it comes to GCSEs.
Seneca. Don't bother paying for it just use the free courses it was very useful when I had little motivation. Free science lessons videos were helpful as well for the tougher areas of science and biology in particular. This is all I did and I managed to get 3 9s in my sciences so they must work. Good luck with your revision.