I took A&P 1 first. and the prerequisite for A&P 1 is Algebra. I do not recommend taking it online because it's more challenging if you are not good at math. Usually other schools require you to take a math course as a prereq. I had statistics but Mercy did not accept that, so I had to take algebra. I took Chemistry at my previous college, but at Mercy, if you take it there, you have to take the lecture with the lab. I was a psych major so my psych prerequisites were covered through my psych core classes. A&P 2 is the prereq for Microbiology, I believe. You have to complete everything else before you can take Microbiology. this class also comes with a lab component as well. I hope this helps.