Bio can really be anything. But all the main topics they can test on will be covered in cliffs AP bio. In OC and GC, all of the topics covered in Chads or Mike's videos are fair game. For QR, its just basic algebra, probability, rates and the new comparison problems. The DAT isn't hard because the problems are difficult, it hard because it covers stuff a wide range of topics. If you use DAT Bootcamp and Cliffs Bio, and genuinely try to understand and learn every topic, you will be on your way to doing great.