I've got Dr. Xu for micro and some people are telling me he tests random facts from the textbook and him telling me he only tests what he talks about. Anyone with previous experience please clarify what kind of questions I should expect on the upcoming midterm, it would really ease the stress for me and for a handful of other people as well. Thank you

Yes, he does test random stuff from the textbook but when I took it last year, he did not do it as much. From talking to people 2 years ago, almost everything was exclusively from the book and very random information. A lot of the test questions are from the lecture slides but he will test you on small, minute details like what is the diameter of a cell, small trivial things you seem are not important but he will test you on it. The textbook is really useful because he uses a lot of diagrams in his slides with not much text so the textbook is an excellent reference for that. Figure captions for the diagrams are good to know too.