Hmm, I just picked up the Pretest Physiology book and had the same reaction. WTF? The questions all seemed tricky and not that relevant to understanding of the subject...kind of a waste of time.
getting 50-60% correct in pretest physio is doing really good. At my school, scoring in this range equaled a high B or an A on our course exams.
Don't get too freaked out by it.