Tim Hunt has published a quick discussion on a new feature coming to Moodle 2.9 which provides additional settings to control how quizzes display their questions to students. The particular settings help to limit visibility to quiz items until a student has met the criteria (kind of like a conditional release of questions within a quiz).
The dependencies are set up to prevent a student from seeing a question which might include context for an earlier item they need to answer.
You can check out this feature and the other cool features we covered recently [features in 2.9] soon in the upcoming release.
Read more about the dependency settings for quizzes at https://moodle.org/mod/forum/discuss.php?d=310239#p1241781 and at https://tracker.moodle.org/browse/MDL-40990.