Whether it's a requirement or not is somewhat irrelevant - I'd think it'd be a good idea to take it since, you know, it's going to be on the exam. But I suppose if you feel comfortable with the material.
Again, you should take ochem 2 because it's going to be on the exam. Biochem will not. I don't know of any schools that will allow you to substitute courses like that. If anything I think it would be the opposite: both courses are more likely to be required (or "strongly recommended").
Sent from my iPhone using Tapatalk