This may or may not be the case for you, but typically, I find that people (including myself) score lower grades whenever their schedule's are impacted with other activities. You're already taking 16 units and have to do well in these classes, add in president of a club, a pre-health frat, shadowing and part-time job, this becomes a struggle. I would seriously suggest you hold off on the shadowing and the pre-health frat and focus on academics more. The part-time job I would say try to hold off on as well, if you're financially secure and seriously focus on the semester ahead of you; but if that's not the case and money is short, the part-time job I understand. I was shadowing, doing research, part of a club and taking 16 units one semester, after dedicating most of my time to extracurriculars, my grades started to suffer, so I stopped shadowing that semester, asked a friend to take over my club duties, asked for a two week extension on my research due date and focused on my classes, come midterm time I was able to turn around my grades from B/B-'s to A's and maintain it through the whole semester. Physiology and Cell Biology are well to do courses that dental schools typically require/recommend so a low grade in these courses is not optimal. If you have time on hand during winter or summer, I'd say shadow or work then so you have more time to focus on the semester at hand. Again, this might not be the case for you, but I would say you getting a 4.0 gpa this semester worth of 16 credits is more important than various extracurriculars, which can be done at a later time.
Good Luck !!
