Always use the Student Portal or Canvas to check your due dates. It is your responsibility to make sure ALL activities, including exams, are completed ON OR BEFORE the assigned due date. All activities, including exams, not completed by midnight on the assigned due date will receive a grade of zero.
The most successful students always stay ahead of the due dates. Complete the activities before the assigned due date. Plan ahead, if you see you have an exam coming up, be sure you complete it before the due date.
The classes are set up so that you can complete all work in advance at your convenience, except the exams. Work ahead, and you will always be safe.