Doing that with pre-med courses is often looked at unfavorably by medical schools, who tend to look down on CCs to begin with and may see a student who has matriculated to a four year school doing that for perceived easier grading. (Students who start at CC and transfer to a four year school would be a different situation, but it is probably best for them to take at least some of the pre-med courses like biology and organic chemistry at a four year school if their major is not something like biology or chemistry that has advanced courses in those subjects anyway.)