I would say it really depends on the person and how well they're able to retain the information they need to do well on the exam. From what I remember, there wasn't much--if any, Microbiology on the exam. It was strictly anatomy and physiology for the science section, maybe even a little general biology mixed in. You'll probably want to individually study the A&P sections of study guides/books to make sure you have a good grasp of all the body systems, their functions etc.
It'll help if you remember a lot of this information from your classes. If you feel like you have to finish the course in order to take the exam, finish it. If not, I say go for it! You really have no idea what they're going to ask on the exam and you want to make sure you're comfortable with a vast amount of A&P knowledge across the body systems.