For chem and ochem sections, taking the basic classes is quite enough. For bio, I would suggest buying a separate book focusing on biology to study with because the DAT does cover a pretty broad range.
I took DATs with just the material I learned from general bio and there were quite a few questions with topics I had never learned.
In case you were wondering, came out with a score of 19 for bio, which I guess will do. 😳