In a lab science it is not generally possible to have the entire grade rest on the final. This semester in O Chem 2 and P Chem 2, the grades are 30% lab, 60% final and 10% tutorial. Tutorial grade is a mix of problem sets, discussion and sometimes an additional written exercise, for example in O Chem they were given an unpublished journal article and told to write an abstract.
In lab courses you must receive a passing grade on both the lab portion and the final exam to pass the course.