I'm trans, but you'll find that the whole "Biological" thing doesn't really mean much here, Well it does but not in an identification way. I like to think of this area as a place where I can freely be the gender that I identify with without judgement. So to answer your question: Yes, there are actual biological females on this site and in this area of the forum, but there are also a few, like myself, who don't like to be bound by the restrictions of biological design.
I like to think of it as a game sort of, not in a discriminatory way, but in a sort of fun way, it's fun to not know who is actually what gender, because honestly who cares? The answer to that question is obvious, or rather it should be obvious. Some people do, but most people don't. And to those that do they probably shouldn't. If you're looking for a girl though who is actually a girl, play some Where's Waldo, that's what I do if I need to ask biological girls a question.
That said technically you could consider someone with the gender operation biologically female since they have all the parts (Albeit not perfectly copied) but thats an entirely different discussion.