This may seem like a really stupid question, since after all, everybody says that undergraduate majors don't matter when applying to medical school, but here it is:
I will be applying to college next year (right now it looks like the list will be Stanford, Brown, Duke, Pomona, and UCLA), and I intend to major in marine biology in college. It's a science that's always interested me; but I'm leaning toward medicine as a more realistic career.
My volunteering and extracurriculars are all pertinent to marine biology (I volunteer as an interpreter at the local aquarium, I plan to enroll in SDSU for the summer session to take some marine biology related courses, and there's a possibility that I'll have the chance of conducting some research in marine biology this year). I plan to focus my college essays on how much I love marine biology. I've done almost nothing to suggest a medical interest.
Now for the hypothetical situation: I get into one of my top choice schools, and after four years of undergrad at that school, decide to apply to their medical school instead of a graduate program in marine biology, as the school would assume I would. Would the college understand this change of heart from marine biology to medicine, or would they tell me that I'm full of bull and black-list me from any of their graduate programs? Would it be legitimate for me to focus my undergraduate admissions essay and my extracurriculars on something outside of medicine, or should I quit the marine biology line and go volunteer at a hospital?