Like twelvetigers said, the last time you can take the test for the year you are applying is october. I look it then and just barely got the scores by the deadline at the end of Nov ( for UGA). I just got a practice booklet and studied that. The boof I had, an REA book, had a pretty good review of the material covered in the GRE. The test is somewhat challenging but it depends on how recent you have had bio..i think general bio, cell bio, and genetics where the most prominent subjects/ pertinent classes. Also, i personally did better on it than the general GRE but I tend to be better at science and found it easier to study for than the general, but it depends on the type of student you are. I think I studied for about 2 months, I studied a little every day and did practice exams on the weekends..i did have a fairly easy semester while I was taking it..so it helped so that I did give a pretty full 2 months to study...hope this helps