You can create a Canvas quiz by finding questions in a question bank (How do I create a quiz by finding questions in a question bank?). When you do this, I believe that a copy of the question is placed in the quiz (which is why the original question bank question is not updated if you update the question within the quiz).
Can anyone tell me what happens if you delete the question bank which acted as the source of the questions after the quiz has been created? Are the quiz and the student results left intact or are there consequences to either the integrity of the quiz or the student results or both?
The Canvas document about deleting a question bank in a course (4152,50749 ) mentions that 'deleting a question bank will affect any quizzes that are associated with the question bank, especially if they have student submissions'. However, this document does not state if this only refers to linked question banks or also to question banks from which questions have been copied.