It sounds like you haven't done much work with relational databases before. In general, the answer is to make a good, normalized schema and then adjust it afterward if something doesn't perform the way you expected. It's unlikely that you will have any performance issues with such simple data on such a fast database, and a normalized schema is so much easier to work with in your program that it will save you time.

If you aren't familiar with normalization, you can look it up on SuperSearch. I recall some good links that Ovid posted at one point. In this case, I would probably have a student table, an exam table, a question table, and a student_question table to hold answers.