I must say Biology is quite critical and not many poor questions survive. However, I still wish to ask the question - suppose there is a poor question that survives reviews, perhaps only barely, and subsequently receives a poor answer. As of now, personally, I leave poor answers to poor questions pretty much alone. In other words, I will not bother flagging it, as a poor question asks for a poor answer. However, if that same low-quality answer was put forward to a high-quality question, I would flag it for deletion. Somehow this is not fair play.
Should we allow poor answers to poor questions? Can we expect high-quality answers to poor questions? Personally, I am not quite keen on putting a lot of research effort in a question where the OP might not have put sufficient effort in writing up a decent question.
EDIT: the suspected duplicate "Flagging incorrect answers" deals with what flags are and when to use them. This question is on specific use of flags in a very specific case. My question is not answered by it.
EDIT2: I define "poor" questions primarily as borderline homework (badly researched), borderline opinion-based, or a question being "formulated in such a way that it very likely will lure new users to post opinion-based answers". A certain fraction of questions is just borderline OK, and my question is on these cases. Poor answers basically follow these conventions here, i.e. borderline research etc etc.