If Biology is not used as a "weeding out" course at your school, I would seriously think about your motivation before you enroll in your next pre-med requirement. There are rough Bio courses out there--for instance the one I took has orgo as a co-requisite and counts as biochem at many schools--and those are meant to scare students with C's...some of the med schools know which schools those belong to, b/c they accept them in lieu of biochem/cell bio, etc. But if you got a C in a standard 1st semester bio course that wasn't brutally curved, I would be concerned what will happen when you go into "real science classes" like Orgo.
I'm not saying you can't do them, I'm just saying I wouldn't do them until you are absolutely positive you are in the right frame of mind, b/c once the grades are on your transcript, they aren't going anywhere...unfortunately. Sit. Think. Rethink. Take them a little later than other people if you need to.