there are alot of general concept questions tested in bio on the DAT but that being said what divides the mid 20's from the 18-20 range is adv concepts + the ability to apply concepts to examples and figure out on the fly the most likely answer.
So I'd study the general stuff til you have it ICE COLD then move on with additional time to the harder questions, bio is a VERY large amount of information so shoot for the spread first then work out outliers.