Definitely go with a science instructor if possible; an A&P instructor would obviously be the best in my opinion. And some advice, if you apply thru PTCAS (most likely you will), without a doubt have the person do the online submission of your LOR. I obviously wanted to get the best grade possible in A&P I last summer, but I tried even harder just to have my instructor write me a good LOR...so got an A, had him send it snail mail, and PTCAS "said" they never got it, along with my LOR from a PT (and why not add they never got 2 of my transcripts either)...grrr...Had to have the pt resubmit it, and my A&P prof never responded to me again (harsh retired doctor who prob. thought I was an idiot after that). So in short, don't leave it up to PTCAS or the mailman to get that stuff in. It's already a daunting enough task w/o all the bs excuses. Good luck!