Those premeds are the ones who grade-grub for one more point when they already have a 96%. Going to office hours and establishing a relationship with the professor just makes you a responsible student. Go to your TA's office hours too! They're a severely underused resource, and not that I know from experience, but there are probably many chemistry TAs sitting in their office hours right this moment eating a danish without any students, bored out of their mind, passing the time by going on SDN instead of teaching.