Moderators have the ability to append real-time answers or replies to questions that are submitted by attendees.

You probably won't want to append answers to the questions that are going to be addressed during the Q&A session, but often times there will be smaller, more detailed, questions that are important to answer but don't necessarily need to take up precious Q&A session time. 

To append an answer, simply click on the question from the Q&A list, type in your response and hit "Save".

Attendees will see a notification that a moderator answer has been added to that question, and they can simply tap on the question to view the response.