The problem is possibly that the original database might well have been developed by a non-professional, and upgrading it to later versions of Access won't help. Newer versions of Access are much better than early versions - Access97 was good, but I think that introduced a lot of better facilities.
In its simplest form, you should be able to add a yes/no flag to the exams table to distinguish a mock exam from a real exam, and change the queries so that they can distinguish between real, mock or all exams.
But the database structure and design might not make it as easy as that. Although posters here often offer substantial solutions to problems, it's hard to do that without seeing the whole database and code. You can't really expect advisors to struggle through assorted images, which may well not really explain the underlying problem. The best solution might even be to start over.