The way you respond to questions will have a major effect on what kind of rapport you are able to build with the audience. If you answer questions thoughtfully and respectfully, people will feel that you are taking them seriously. If you give flip, dismissive answers, people will feel that you don’t have time for them.
People may ask questions which are not a hundred per cent serious, but even then you should not be dismissive, simply take the question in the spirit it was intended and take the opportunity to display a sense of humor.
Questions may well be an opportunity for you to get information into the presentation that you could not address due to overall time constraints. When someone asks a good question, begin your response with a sentence along the lines of “That’s a very good question, and I am glad you asked me that. I think the most important thing here is that…”
If someone asks a question which you find either you cannot answer or which is difficult, do not simply say “I don’t know” but say “That’s a good question. I have to admit I hadn’t covered that issue – what do you think?” This way you will not lose respect, but will allow discussion to flow more freely.