Make-up exams are generally not allowed. Grades can be bumped downward by unexcused absences. Grades can be bumped upward by participation in class discussions.
Homework is assigned, and class time is allotted for discussing homework problems.
Homework is not collected or graded, but it is the basis for questions appearing on the exams. Finite Dimensional Vector Spaces by P. Halmos Linear Algebra, Third Ed.