The school I applied to recently takes only your first attemp at Chem and Bio, even though they make you retake them if they haven't been in the last five years. My first attempts were a big party year at a big party school. I had a lot of fun, and my GPA showed it. Since then, as a returning learner and a wiser individual, I have had excellent grades.
I was able to make an appeal to the univeristy's Academic Committee in regards to those couple of zeros for grades, basically asking that they don't allow one rough period of life, 25 years ago define who I am today. It was granted, so those grades were not averaged into my entrance GPA. Doesn't hurt to ask, or try.