The Question Bank is the pool of questions that feeds quizzes in a course. You can set up pools of questions in categories to pull from at random or specifically chosen questions.
Generally questions should be entered into a question bank but they can also be entered directly into a quiz within Moodle– one at a time with the Add a new Question option from the Add menu. Questions added this way may not appear in the question bank and thus be available to other quizzes.
Once you find your way to the Question Bank for your course you can create categories as you please, as deep as you please.
Once you’ve got the category containers ready you can fill them by importing plain text questions in AIKEN format, importing questions from publishers or other instructors/classes, and even export your own categories of questions for other instructors to use on Moodle or other Learning Management Systems.
Now you can go and add these questions to your quiz(zes).