I've just completed first semester of grade 11 and ended up with downright horrible marks. First semester average was just 81%. This was mainly due to lack of effort, and the fact that I had to deal with all three sciences and functions this semester. I am wondering will this have any effect on university acceptances to either U of T or Mcmaster? Also, do universities look at your second semester grade 11 marks and your grade 12 marks or your whole grade 11 year plus grade 12 first semester for acceptances? Thanks!

Try using the search function, this question has been asked hundreds of times.

Your grade 11 marks will only influence if you get early acceptance. However, I'm almost positive that both Mac and UofT do not look at grade 11 marks, that's why most people start receiving their acceptances in February and after.

As for your second question, they accept students in waves. I believe there are 3 waves.

November-January: Schools look at your grade 11 marks ONLY. Grade 12 first semester midterms are not taken into consideration.

January-March: First semester grade 12 marks. At this point, grade 11 marks have no purpose I believe. They are just looking at your first semester finals.

March-May: First semester finals and second semester mid terms. Once May 25th rolls around, all schools will have sent out their acceptances.