I’m not really understanding the question. If your question is can you take a higher level course because you have AB/IB credit for gen chem/gen bio, then the answer is generally yes, although in addition, organic chem is always required anyway, and biochem is often a requirement. If the question is can you take a lower level chem for dummies type class, then the answer is generally no. The college’s pre-health advising office can provide more detailed help, as each med school can have its own nuances in terms of requirements.