have you ever failed a science pre-req more than once?

It wasn't a science pre-req but I failed Spanish, was accepted into a nursing program with the understanding that I would have to repeat it, took it online right before graduation and I'm certain my professor passed me just because I worked extremely hard and she felt really bad for me.

Anyways, even with science pre-reqs if you fail it, its not the end of the world but you will of course need to re-do it. Failing a class is never ideal (its discouraging, costs money, is very stressful) but assess what you did wrong and you'll be ok. As others have mentioned, if you're really struggling with something like an Anatomy course, I would spend a great deal of time assessing your study habits and strengths, since that is a core foundation for many of the nursing classes.

As for as programs, some schools accept grade replacement, others won't. You will just need to find a program that works with what your your current situation is.

Well, kind of. I didn't fail A&P I. I got a C, which was too low to continue in the program I was in. (It was a req for my first Associates in health information management). I took it again the year after and got an A. I completely changed up my learning style because after a year of more intense courses under my belt I had found a way to take notes and study that worked for me. I was also way more organized and took the class with a different prof (not good or bad, just a different teaching style and it worked for me somehow). The next year I took A&P II with the prof from the first A&P I class and I aced that course. I really think what helped was being really organized and knowing how my brain works so I could memorize more efficiently. Took me a while to start applying to nursing schools (moved 1000 miles, got nervous, etc) but now I'm in a BSN program!