AP Biology and AP Calc in the same year? Wow... I took AP Biology as a sophomore, and I'm not taking Calc until I'm a senior.
Here are some tips I gave to someone who was considering dropping the class:
I took AP Bio last semester as a sophomore. Our first test was over about 5 chapters, too, and it was 50 multiple choice questions and 2 FRQ's (basically, those were a free ten points). I got a 96 on it, and a lot of my classmates passed that one (70's, 80's, several in the 90's). However, the rest of the tests were a different story... I'd say that if you were to eliminate the outliers (the kids who did consistently well on all the tests), the class averages for the rest of the the tests were probably around 40-ish. And it's not because nobody studied... it's that many people didn't know HOW to study. AP Biology is a hard class.
My AP Biology test grades were in the 80's and 90's (not meaning to brag, but that's pretty rare for this class if you have a good teacher). What I did was I took lots of notes in class (lol I took a lot of unnecessary notes, but I felt safer that way). Then, I went home and studied the material for about 3-4 hours. During those hours, I...
1) Read the chapter(s) discussed and looked over my notes.
2) Re-read the chapter (skimming through)
3) I got a study guide/student's companion to my textbook... they had like 20 multiple choice questions for each chapter. I answered those questions and made sure I really understood why each answer was what it was. Ironically (note the sarcasm =P), very similar questions almost always showed up on the tests.
4) If possible, I looked for animations pertinent to the lesson. Many people are visual learners.
5) My favorite strategy: Talking to myself, or "teaching a class." I'd always pretend to be teaching a class about what I had just learned in class that day. If you really knew a topic, you'd be able to do the same thing.
Yeah, it seems like a lot, but this is a college level class... maybe your next test will be better since this one was more self-study. But if not, then that's really not an anomaly for an AP class. AP Biology is good in that it has a lot of "filler points," extra credit opportunities, labs, essay practice, etc. Most people do end up with A's and B's, even those who were consistently scoring in the teens, twenties, and thirties on the tests. So don't drop the class just on account of one bad test grade. Study for the retake, do your best, and find a study strategy that works for you!