I'm trying to register for Biochemistry 2201, I've done all the prerequisites, I'm doing the corequisite, there's space in the course but the system won't let me register.

If this happens to you, it's because you must register for your courses in the proper order. You should register first for Physics 1021 or 1051 (if you haven't already completed the course) then you should register for  Biochemistry 2201.

 

I'm trying to register for Biochemistry 2200 and the same thing happened.

Once again, the order in which you register is important. You should register first for Chemistry 2400 (if you haven't already completed the course) then you register for  Biochemistry 2200.

 

Can I get a prerequisite waiver for Biochemistry 2201?

NO!
You must pass one course in Organic Chemistry (either Chemistry 2400 or Chemistry 2440) before you will be admitted to Biochemistry 2201. No pass, no admission!