(a) Except as otherwise provided in §§ 503.73, 503.74, 503.75, 503.76, and 503.84, every portion of every meeting and every portion of a series of meetings of the agency shall be open to public observation.

(b) The opening of a portion or portions of a meeting or a portion or portions of a series of meetings to public observation shall not be construed to include any participation by the public in any manner in the meeting. Such an attempted participation or participation shall be cause for removal of any person so engaged at the discretion of the presiding member of the agency.