Can Branches and Merge Requests be hidden from other Developers?

My University’s Mobile Computing course uses GitLab Community Edition for its group project, and we’re hoping to use it in the Labs, to let students get more practice with Git and make labs more engaging. The hope is that they will be able to check out the week’s lab assignment, make their changes, and create Merge Requests, which will be what they will be graded on.

The problem, however, is that if the students are all able to see each other’s branches and MRs, they may just copy each other’s work. Ideally, a student would be able to access only the Master branch, and their own. Is it possible to limit the visibility of branches and MRs in this way?