Physics calculates into your BCP gpa, so it is more important than some science classes. Most schools won't take less than a "C" in a prereq, either. Although, if you're getting C's in prereqs, you should probably retake them or take an upper level course in the same discipline to show that you can handle the material. A "C" isn't a competitive grade for any dental school.
You're asking the wrong questions though. Just do your absolute best in the course, it's all anyone can ask of you. You can do it. "Every passing moment is another chance to turn it all around"!