A large part of learning biology is memorization; there is no running around the amount of material you have to memorize. A lot of great advice has been posted about using OneNote, Quizlet, and someone will eventually post something about Anki. A method I used to learn and understand biology, even more, was to pretend like I was giving a lecture. I would go to an empty study room and begin by collecting my notes. I would briefly look at the topic, then recite things as if I was lecturing about that topic. The key is when explaining, explain everything you know without hesitation. You will be forced to regurgitate what you can remember as clear as you can. Imagine if a professor was hesitant with their lecture and wasn't clear about what they were talking about; this would make you question their knowledge and credibility. The moment you start hesitating, take a quick glimpse at your notes to see if you can pick it back up, and if you can't, study it more until you can.
It also helps to become the student as well. After explaining a topic, if you yourself have a question, ask it out loud, and then proceed to answer. If you can't, then you can go back to your notes to see if you can; if not, then save it until after you're done lecturing everything else from your notes. This is a method that works for me and it still does. However, everyone has a unique learning style so this may not be effective for everyone.
Note**People might also think you're a mad genius or in short crazy, for talking out loud and answering your own questions especially if you become REALLY interactive.
Good luck to ya!