My experience has been that many people may say the bio section doesn't require THAT much outside knowledge. However, I saw the biggest jump in my bio scores after memorizing 500 or so high yield facts.
Compared to chemistry and physics, biology is not so much theoretical in that one may be led to believe that a certain bio question can be answered by pure logic from a general principle or info from the passage, but in reality, that question deals with a specific matter of fact that just can't be deduced. I think people can get ok bio scores using either factual knowledge or pure reason, but the best scores come from using both. The catch is that memorizing all those facts gets really annoying after a while!
Of course, I have no idea what your strengths and weaknesses are--just focus on the weaknesses, because that's how I got the biggest return on time spent. In my case, my biggest weakness (aside from careless reading) was not knowing immediately what was going on when, for example, adrenocorticotropin was mentioned; or thinking I knew the cellular organelles, when really I only knew the names; or thinking I knew what parathyroid hormone did, just because I knew it increased calcium in the blood.
And always important to remember that even if the correct answers have nothing to do with the fact memorized, knowing just one extra fact could potentially help you to answer infinitely many questions by process of elimination.