I just took the DAT today. I got 22 Bio, 22 Chem, and 26 Ochem. I used Chad's videos, Kaplan, and DAT Destroyer. Despite what a lot of people say about Kaplan, their online resources are good. Their sciences in my opinion are harder than the real DAT in terms of their online subject tests and full lengths (I don't know how the KBB compares, I never used it). Particularly Kaplan is overkill for O-chem. If you score 20+ on it be prepared to murder it on the real thing. I know your pain in bio, do not freak out because I never broke 19 on any Kaplan practice exam. Have comfort knowing that Kaplan's rating system is messed up. I took a full length and missed 1 question and it gave me a 24 which is definitely inaccurate. I noticed Kaplan consistently gives lower scores for sciences, I really don't know why. My best suggestion for you in Bio is just practice at this point but its important for you to really go over which questions you missed and see why you missed it because its a weak point. I figure by now you covered all the material, now its just time for you to close any holes in your understanding but that only really comes through practice problems. So for example, if I missed a question on the lysogenic cycle, I would go back and read up on viruses and come back and see if I could now explain the answer easily. Do that enough and you should be golden.
For PAT, I got a 21, I used CDP and Kaplan. I think the biggest thing for me to breakdown each section and see why I was missing those questions. For example hole punching used to be my lowest section. I would use Kaplan techniques like symmetry but in real testing, your hole punching questions are far too complicated to get away with just using that. I got demolished in CDP just using this method. So I searched online and found that the tic tac toe method was best for me and it ended up being my strongest section where I always get 100%. What I am ultimately saying is that you need to break down each section and find a method that works best for you to approach each kind of problem. Dont just take a bunch of tests and hope your score gets higher. Actively pursue a "method" that will change your old method of doing things to raise your score.