Principles of Animal Physiology
Others seem pretty frustrated by this class but I really enjoyed the material and Grunwald as a professor. It's true that his quizzes are pretty hard because it's hard to figure out what he's looking for. Also, his lectures are pretty disorganized.
This was kind of a strange class. The material was sort of inserting fro time to time but the structure was disorganized. It's not necessarily hard but I don't think I would recommend it.