Yea, I relied heavily on the Kaplan book. What a mistake! I am also a biology major and have taken a number of upper division biology courses. For the most part, I felt as if the bio was just random. If you read the Kaplan book, you will do well on the Kaplan exams. The actual DAT has a MUCH broader scope of questions than Kaplan (I had around 6 important bio chapters that didn't show up on my test). I was averaging around a 25 on the Kaplan and Topscore bio sections and did not hit close to that high on the real DAT. With that said, I still got above 90% on the exam so it is sufficient to get a pretty good score. In order to get these 24s like some people on this forum, you need a little bit of luck. Good luck!