Question About University Admissions?

Hello. I would like to thank you in advance for your help. I will be applying to a Canadian university next year and one thing has puzzled me. The university which I am talking about is UBC. According to their site their admissions average is calculated using your grade 12 English grade, as well as Maths, and two other courses. For me I believe that it will be Bio and Chem. If university admission replies are sent out before the end of the year, how do they get the marks for second semester classes which are not finished? Do they simply take the current mark? Thanks again.