the last poster was correct- osteo takes higher and allo averages the two.
my advise, as someone who had a heck of a time w/science courses early on, is NOT to retake unless you got a D or F;
you won't really impress anyone with an A in intro bio if you got a C the first time around- you'll be expected to earn an A b/c you've already done it and anything else could be the nail in the coffin for an ad comm.
if you pulled about a C or better take more advanced courses, work hard- really hard- and prove you're better than your past mistakes/shtcomings and you can rise to the challenge.
i'm far from infallible, but i'm writing as somone who went from 2.5 to 3.8 sci gpa and will be starting at nycom this fall (GOD willing).
best of luck in your journey