i've actually taken a princeton mock exam nov 2016 and some of the bio questions were very specific to the princeton DAT prep book - about 2-3 questions. that being said, the rest of the questions were very similar to the real dat in terms of simplicity and some "tricky" questions. i would obviously take the mock exam with a grain of salt. because any mistake you make on that exam can hint at you to study a little bit more of that section (which I did for practice)
chemistry was on par as well, some difficult questions, some very simple questions.
because i took the canadian mock exam, i don't know about math and orgo
RC is RC lol, just practice with scientific american and read up on other posts that go super detail into RC strategies