Try to memorize everything. You may or may not want to be selective about what you study up on plants (I didn't have any questions about plants on my DAT, but I was prepared for them). Don't try to learn everything at once, but if you study 3-5 pages a day you will be set for Bio. You don't even need to use Cliff's A&P book because a lot of the notes from Feralis come directly from that book.