I've applied for both Mac kin and life sci and want to know which will be easier to achieve a high GPA and fulfill the reqs for med school. I'm interested in both and wouldn't mind going into either if I got accepted to both. However, I'd also like to be practical and choose the one that will help me receive a higher GPA.
I applied for biopharm co op. Is that life science?
Also, is there a co op form that I need to fill in somewhere right now or is that during the third year?

If you really wanted to be practical, you'd choose a program that allowed you get the most out of learning and worry less about the 'easiness', and how it would help you get into med. There isn't one program that's 'easier' or 'harder', it just depends on your general aptitude right?
By the way, I'm pretty sure biopharm co-op is for upper year students only, and you'd most likely apply during 2nd year.

Yeah, you definitely didn't apply for biopharm if you're just going into first year. OUAC asks for your areas of interest to help the university with planning for the future. As Angoose said, you apply to biopharm (and all science co-op) in your second year, to start in your third year.

Pick whichever one interests you more. No one will be able to tell you which one is easier, as that is a very subjective question. If you study something you like, rather than something someone else tells you is "easy" you will get better marks.

if you want to go to med school you have to be able to do the work, no matter which program you are in or else you are going to be screwed for med school. both programs have their pros and cons, kinesiology is much more specialized whereas life sciences is a basic first year and then you have the opportunity to specialize in your second year (ex: psych, biochem, chembio, etc) OR you can just stay in honours life sciences which allows you to choose a variety of subjects from all science fields. In this way you may assume life sciences to be "easier" because you are able to CHOOSE courses that you WANT to take...more elective options which means you will probably do better if you actually like the coursework.

I know nothing about kin or life sci, but I do know that you should have a fallback plan if med school doesn't work out. It's rather hard to get in, and your mind might change between now and then (as did mine with law school). It's easy to feel burned out after a bachelors degree and not feel ready for more schooling.

Tl;dr: consider which program gives you more options if medschool doesn't work out.