A quorum at any regular or special meetings of an advisory group shall be necessary to transact business. A majority of the advisory group's appointed members, excluding vacancies shall constitute a quorum. A quorum must be present at the initial roll call at the commencement of any regular or special meeting. The necessary quorum for conducting business of the advisory group shall be determined by a majority of each membership and included in the bylaws for each body. For the purpose of the election of officers, the necessary quorum shall be a majority of the duly appointed members.