Hello, I just passed the Biology CLEP with a 71 about two hours ago! This was my 10th CLEP exam and by far the most challenging one I have prepared for. I passed all 9 of my other exams using only InstantCert and the Official Study Guide questions. This one was different. It took me nearly a month of study as follows:

I went through all of InstantCert's material twice, compiling a 118 page study guide from the questions I got wrong. I even did a couple of sections three times. Then I rented the Standard Deviants video from NetFlix (good overview). After that I crammed from my study guide before taking the practice test and still only got a 58%.

At this point I followed the advice of others in this thread and purchased the Peterson's practice tests. They were extremely helpful and I recommend them to anyone taking this test. The actual exam was pretty close in difficulty to the first two Peterson's tests. The third Peterson's test was way harder than the actual exam. Don't worry if you bomb that one. I also used Wikipedia to learn the major Phyla and the PBS flash thing on Mitosis vs. Meiosis that several people mentioned.

Even with all that study, I didn't think I would do nearly this well. I am really happy to have this one behind me. I enrolled at Excelsior College a few weeks ago. I now have 84 official credits towards my BGB.

36 to go! Good luck to everyone,
Chris