In cases where you guys come back asking 'have I answered this question with enough detail?' after a SAC. If you're inside a SAC/exam sitting there thinking that, write more! It's as simple as that. Writing more isn't going to hurt. The way I did all my writing exams (Bio, BM etc.) was to do a 'superficial' answering first where I just cover the questions, then go back and add as much as I possibly could with the time remaining. Of course you don't do this if you're struggling for time already and can't finish the paper as is. Reason is because in most cases it isn't necessary to do this to get the marks, but it just covers me for the cases where I'm not sure or where the examiner may have taken marks off because I actually was unknowingly too superficial in my first answer. As for the example specifically, that's more of a BM thing but it can be used in Bio. Rather than always an example though, at least clarify terms further or whatever. My point in that post was more to just keep writing rather than specifically using an example - that's just one method of giving more detail.