Bio is an extremely broad topic so I'm not sure that any one study guide, in and of itself, is capable of totally preparing you. I can tell you however, that the DAT Destroyer bio questions practically cover everything you will see on the DAT, with the exception of one or two unpredictable questions. Destroyer Bio was designed to probe you in every area of biology, and through its comprehensive solutions it will force you to learn the essential concepts you will need to master the bio section on test day. I say this because I got a 24 on my Bio section - so I know that Destroyer Bio worked for me. Good luck!!