I got a 23, so not as qualified as some, but I used Anki. Using Anki to make flashcards is very slow going but it allowed me to study for the other subjects more as I got closer to the exam day. This is because I learned the material so well I remembered it permanently (as opposed to some people that quickly read over the material cramming it in short term). IMO just reading the Bootcamp notes without some active involvement is not the way to go. I am a decent reader, got a 25, but I would retain nearly nothing by just reading biology notes doing nothing else.
Biology is a tricky section because you have to know the small facts and details, but the scope is also massive. I knew the Bootcamp notes super well, studied over about three months for probably 5 hours a day on average (just biology) and that was enough to get my score. Good luck!!