Yes. I'm doing it in 3.5, but it's a ton of work, especially this semester as I'm studying for DAT and doing orgo 2, cell bio, stats, and philosophy (4 page essays every week!). You can do it, but try not to burn out.
YES! I will be completing my BS in biology and graduating spring of 2015. the key is to WISELY disperse your biology courses! this means every single semester you'll have to take at least 1-2 biology course along with chemistry and other electives to balance it out. My freshman year I took the regular 16 credit hour classes but my second year, I amped it up and took 19 and 21 credits. It's do-able, but really hard especially since you literally have no time for anything else.