If it is a requirement, you have to take the class. Period. End of story. Don't waste your time asking for an exemption or risking your acceptance on such a minor detail. Just take the class.
True story, my med school required 2 semesters of biochem, which at the time in 2005 was unusual. A kid that I knew in undergrad got accepted early decision, was in the first semester of the biochem course sequence at that point, thought the acceptance was binding and never signed up for the second semester. Shows up for orientation the following August, starts classes, everything seems fine until the day before the first exam 2 weeks in. Yeah, they finalized going through everyone's transcripts that week noted the lack of the second semester of biochem and said "Don't bother showing up for the exam tomorrow." He hired a lawyer who basically said he was SOL. He reapplied the following year and was rejected from my med school citing character/professionalism issues. I think he got rejected at a few other places when they heard the story and eventually ended up going to dental school.