If you go to a decent CC, your science classes should be just about as equally hard if not harder than University ones, as often they aren't curved. The upside of the CC is that you have a much smaller class size, 20 compared to 400 for intro bio at my schools, and the teachers are much more dedicated about teaching than those at research universities. Non-science classes will be pieces of cake if you pay attention.
Back to your question, do you mean transferring from a CC or a State School to a University? If you're in CA, it's much easier to transfer from a CC than it is from a CSU because they reserve seats at the UC's for transfer students from CC's, but not from CSU's. Also, most of the UC's have guaranteed transfer programs. For example, the school I went to, UC Irvine, said that as long as I got B's in my year of G chem, and got a 3.0, I would be accepted to the university and the school of Biology. I know UCLA has a similar program.
If you meant do you have a worse chance of getting into a Uni after going to a CC, I would say no.