This is not something we currently support but you can add or vote on feature ideas:
If you need to add a new idea click "Create an idea" under "Actions" in the top right.
Although Josh is perfectly correct, and this is not currently directly supported, it should be possible to simulate this. This would be easiest if all of the questions are multiple choice or numeric (things get rather tricky if judgment calls are involved).
Assume you have 3 questions. Your table will probably have 4 columns: (A) Time Submitted, (B) Question 1, (C) Question 2, (D) Question 3. The simplest approach would probably be to add 3 more columns (1 per question):
E with an formula like: = B = "correct_answer_for_question_1"
F with an formula like: = C = "correct_answer_for_question_2"
G with an formula like: = D = "correct_answer_for_question_3"
With this, your columns E, F and G will contain checkboxes representing whether they got the respective question correct (if they got question 1 correct, column E will have a checkmark).
If you wanted automatic scoring, you could add a new column, H, with and expression like: = sum(E:G) / 3
If you format H as percentage, you'll then have the submitter's mark for the test.
I'm sorry if this description sounds rather sketchy or abstract -- if you can provide me with more specific details of your test, I can give you specific formulae, etc.