If you just focus on biology then your studies will concentrate on it along with the prerequisites required. Speaking from a medical standpoint, and you went back to school you could skip some of the prerequisites required since you would have those college credits acquired. Personally, I'd speak with your student advisor as they know specifically how your school operates. But, you need to ask yourself, do you truly want to go back to school when your done? Or, just have them integrated if possible? Most colleges students have assigned classes which are part of the program others do not. I currently have went back to school after being out a few years. I'm now a therapist. But I was a CNA then RN. Time management is utmost importance and keep a schedule that works for you. Do not get overwhelmed by your studies. Most schools have a class to learn about time management; however, I do not know which school you attend. Ensure you do not over-do your credits too. Within the class I'm speaking on,they should describe studying time per college credits and the requirements to set aside for proper academics. I know for a two college credit class I study about 2 or 3 hours per day. taken "brain breaks" are highly beneficial so you do not get burned out and crash and cause stress. Meditation has helped, too. I go to Grand Canyon University in AZ. I have three classes, and I am top of my class. I am also, a mom. So, if I can do it, you can! Try making a pro and con list, or look at the classes for both side by side, to see which would be a better fit. Both, are highly rewarding. Both benefit a greater good, of helping, and sharing compassion to those around you. Medical was a natural calling for me. However, once I took psychology I just kept going back to it. I was a natural at that, too. Which ever you decide; best of luck.