(1) Unless otherwise provided in the certificate of incorporation or this act, the holders of shares entitled to cast a majority of the votes at a meeting shall constitute a quorum at such meeting. The shareholders present in person or by proxy at a duly organized meeting may continue to do business until adjournment, notwithstanding the withdrawal of enough shareholders to leave less than a quorum. Less than a quorum may adjourn.
(2) Whenever the holders of any class or series of shares are entitled to vote separately on a specified item of business, the provisions of this section shall apply in determining the presence of a quorum of such class or series for the transaction of such specified item of business.