McMaster Life Sciences doesn't look at grade 11 marks.
Here are the courses that are required to obtain an offer. Try to aim for a 90 average in your 6 courses because the cutoffs for Life Science are usually 87-89%. ECs don't matter at McMaster.
Another alternative you should consider is the Health Science program. You need a minimum 90% average to be looked at, and there is a supplementary application with essay questions for you to answer and admission is done by selection. ECs still don't really matter here.
I noticed you didn't list physics in your courses. I would HIGHLY recommend that you take physics while it's still free because you'll at least have some exposure to the material before doing it. Keep in mind that you're paying for your courses now, so there aren't really any second chances. First year physics is
required for First Year Life Sciences but most Health Sci's do it as well. Also keep in mind that no matter how poorly you do in it in high school, if it isn't used in your top 6, it doesn't really matter. I know a lot of high schools students avoid hard courses because they want that "Distinguished Honour Roll" that their school gives to students who have 90%+ averages for all years but those actually mean nothing. Doing poorly in a course that is not in your top 6 will not affect your entrace scholarship either so just something to consider.
