I suppose it wouldn't hurt to start studying. Do you have any background in bio, other than high school? Honestly, not that any of the other sections are easy, but Bio is difficult because it covers such a broad range of topics. From the organism to the molecular level. From your standpoint, yes Bio is a must. If you'd like, get a supplemental program from Topscore or something. That'll give you a taste of what you're in for. Good luck!