Do Medical Schools care if I took 4 courses first semester, 5 courses 2nd semester and 1 course during the summer in my First year as a Life Science student?

It really depends on the Medical school you are thinking of. Some will not include your GPA if you do not have a full course load, some like McMaster, will count every single course you have taken throughout your undergraduate years.

Check out two articles on Med school that were posted earlier in the summer, here and here.

Yup depends on the school. For some schools that is fine (i.e. Western) but for others it will not be.

Some schools e.g. U of T don't count summer courses towards your GPA. I would suggest visiting the sites of a couple of schools, or the ones you're considering to attend in the future to find out how they view a full course load and/or summer courses

I'd suggest you include the appropriate number of courses that will open the most doors to you once the application time comes. Since we all know that med school is insane to get into and we want to qualify for as many as possible.

Here's an article that I wrote that will likely answer your questions: http://www.macinsiders.com/showthread.php?t=2191 6

If you can, take a full course load (30 units) during the year to maximize the number of schools that you can apply to with the highest possible cGPA.

If you don't take a full course load in first year, then you'll lose U of T's "drop your two lowest 3 unit courses per year (or 6 unit course per year)" marking scheme. Also, University of Toronto does not take summer courses into your GPA.