They give you a small scenario a few minutes before the interview. An example is something along the lines of...
A woman wants to have a C-section but her husband doesnt want to go through it (wants a natural birth, i think). Then you have to argue whether it is permissable to have the C-section or not.
In this case you would have to give both for and against arguments, seeing it from the husbands point of view as well and then discuss the ethics of it. This was the one I had last year, but there are quite a few scenarios they could give you.
The best thing to do is to write all of your points down on that piece of paper and read off that in the interview, so you don't foget any of your points.