Biology subjects are definitlety some of the most dense to make notes for - I feel your pain!
I started out annotating the slides with a summary of what the lecturer said, but I found that it made it harder to really cement the knowledge in my mind. Now I've found it best to take a two pronged approach - annotate my slides in the lectures and rewatch the lectures (1.5 x speed) if I feel I didn't have time to write down any important verbal points at the end of the week. However, I also have a notebook for each subject that I handwrite summary notes in, re draw important diagrams and compile a glossary for the subject. I do this on a week's delay, so that I can get a sense of what were the most important parts of the previous week's content, or the areas that I understood less. This also allows me to draw extra information from the readings or outside sources if i need to. I find this book much more useful than the lecture notes come exam time, as it is a single document and I can format it as I see fit.
Hope you find a method that works for you!