Hi there!

Firstly, I'd like to specify, biology is not about memorising stuffs. It is all about understanding the concept once, practising several times and linking it with other concepts.

However, there is a small portion of the subject that needs to be remembered. This portion definitely needs to be dealt on regular basis to keep them in memory. 

But the major chunk needs conceptual understanding by visualising through diagrams and flowcharts, after which you will never forget those topics.

Thanks