I know at my school they only required one semester of biochemistry, I took biochem 1 and 2. Glad I did that because it was a breeze when I got in, finished with a 96% in the class. Taking physiology now, that helped a lot in undergrad too as a good chunk of it is just a review. You'll be busy with a lot of classes so it's helpful to have seen the information before so you can focus on things you haven't seen or subjects that are harder, which is gross anatomy atm for me :|. I took anatomy 1 and 2 in undergrad but it was far different and in much less detail than what we are having to deal with now.
I agree with someone from the above about the business/finance/account classes if you can afford it. As predents to dental students, we were/are mainly worried about either getting into dental school or finishing. When you're out and working though I've heard over and over that it's a whole different game there. They don't really teach you much of that.
Pharmacology at our school is also one of the harder classes d2 year, maybe that would be beneficial to you. Histology, I took it undergrad but honestly I don't think it made a difference either way (for me at least).
Good luck.