Shown below are the steps for backing up an individual activity in Moodle- a quiz.
First display quiz page
The initial settings page appears
Next go to the course you want to add the activity to and select Restore. Upload the backup file that you downloaded and click on Restore. A page with Backup details and Backup Settings will appear. If the details and setttings are correct, click on continue. You will be prompted to select the course to restore it to. Select the correct course and then continue through a number of screens in which you confirm that you have selected the right activity with the right settings. Your last step will be to click on Perform Restore. You will then see a message that the course was restored successfully.
Restoring a single activity will not erase any existing portion of your course. Whatever section the activity or resource was located in in the original course is the section that it will be restored. For example, if you restore a quiz activity that was in section 4 of a course, it will be restored in section 4.