The end of the discursive essay leaves room for you to offer some kind of opinion or solution or suggestion related to the question. For example, with the question of "Smoking should be banned...Discuss..." you could write something like:

"Although there are some reasonable arguments against the ban of smoking, I believe that the benefits outweigh the drawbacks. The ban itself could be applied in steps, giving smokers time to cope with the necessary changes they will have to endure. Ultimately, this will be of greatest benefit to all."

This gives the reader/teacher the knowledge that you are able to offer some of your own ideas on the subject and gives a good ending to your essay.