Biscotta

At my school, incoming grad students take exams in all the subject areas (organic, inorganic, P chem, biochem or analytical). If you don't pass any of them, you end up in the undergrad class for a semester. It doesn't count toward the grad-level classes that you need to take but most people take 1, and some take 2. It isn't really a big deal. I also did biochem as an undergrad and chem as a grad, although my research is very much biochem. My biochem major required two upper-level chem electives (organic and analytical), and I took a third (inorganic) to make myself look a bit stronger in chemistry. So I would recommend taking whatever chemistry you can fit in, but don't stress out specifically about P chem. Then again, at my school, pre-reqs aren't strictly enforced (for undergrads or grads). If your school does enforce them, you could possibly talk to the professor about it. In my experience, professors are usually receptive to students who are genuinely interested in taking their class (and not just taking it because they "have to.") The P chem class might have you working a bit harder if you don't have the right pre-req but I would bet the professor will review anything that class covered that will be relevant, albeit probably at a faster pace than the original class.