There are female krogan in the Urdnot Camp in ME2. They look and sound just like males, if that's what you're wondering.
Are you sure about this? Mass Effect is one of the very few games I've ever obsessed about, and I don't recall seen a female Krogan nor a female Turian for that matter.
I've read in different places that this was due to technological limitations, and by now I'm seriously expecting some kind of galactic joke when the first female of both races (and some others) are introduced in Mass Effect 3.
The only resemblance of a female Krogan I saw was in an room where Mordin (the saladian doctor) founds a dead body of one female which was being experimented with. She was represented as a dead body completely covered, so the speculation remains.
I'm also expecting to see the bare face of the quarian race.
All in all, I might be expecting too much out of that franchise... yet I'm still hopeful Bioware can come through with this one.
Sauce!
hxxp://masseffect.wikia.com/wiki/Krogan#Trivia
"Only one female krogan has been encountered thus far; she can be found during Mordin Solus' loyalty mission, lying dead on a table under a tarp. She is noticeably smaller than male krogan."
hxxp://masseffect.wikia.com/wiki/Turian#Trivia
"No female turians are seen in any of the current games. This, at least in the original Mass Effect, was because there was insufficient development time and memory budget to support two different versions of the same species."