Thanks Rick and Tim,
Rick, re "If I give a quiz on Chapter 2, why should this quiz need to know what the student has answered in Chapter 1", the use I'm thinking of is if you want to use a quiz to test someone on the entire course by giving them randomly selected tests of similar difficulty at different intervals throughout the course.
This is how I'm planning to use it, with the offline course being from beginner to advanced in a second language - it's part of our assessment of student progress with their language proficiency.
A similar use might be to use quizzes that test students on their readiness to take an exam (the new MEC perhaps) so they can see their progress at regular intervals even though they haven't completed the course. It could be particularly useful when whole tests or groups of questions are benchmarked against each other for difficulty level.
Having said all that, I now think that a single quiz will work for our context because students will be able see their results from each attempt in the quiz itself rather than the gradebook, so thank you again for letting me know about that, and thank you Tim for taking the time to look at this from a plugin/coding perspective.