No, if you have unprotected sex with a straight white (not sure what race has to do with it) person who has HIV then you can obviously catch HIV.
Is this a serious question?
Whatever college professor told you this is an idiot.
I think you might need to enroll in some kind of sex-education course. The only dumb question is one that isn't asked they say... but this is a dumb question. I'm glad you asked it however, at least you must have some awareness at what a dumb statement this is to make. If I were you I'd inform a more senior staff member that this college professor is an ignorant fool and giving people dangerous advice.