Take each biology course ONE AT A TIME... I've seen many people try and tackle both and end up having to drop one.. These courses take tons of studying and you cannot afford additional distractions....
I would never recommend taking a science online... Especially in your situation.. Online courses take a lot of discipline, and that may be very hard working with two children. I am a mother of 3 and...
If I were you I would repeat the courses you got a C, C+, and B- in. Most schools I've come across require a minimum of C+ or B in prerequisites outside of the science pre reqs. The higher your grades...