This diagram might help a little, though Tims reply is a reminder to me to go further with my quiz diagramming.
http://www.examulator.com/er/components/quiz.png
Quiz
Where are quiz question comments located in the DB?
གྲོས་བསྟུན་འདི་བསྡམས་ཡོདཔ་ལས་ ལན་གསལ་བརྐྱབ་མི་ཚུགས་