(a) The holders of a majority of the votes of shares entitled to vote thereat shall constitute a quorum at a meeting of shareholders for the transaction of any business, provided that when a specified item of business is required to be voted on by a particular class or series of shares, voting as a class, the holders of a majority of the votes of shares of such class or series shall constitute a quorum for the transaction of such specified item of business.

(b) The certificate of incorporation or by-laws may provide for any lesser quorum not less than one-third of the votes of shares entitled to vote, and the certificate of incorporation may, under section 616 (Greater requirement as to quorum and vote of shareholders), provide for a greater quorum.

(c) When a quorum is once present to organize a meeting, it is not broken by the subsequent withdrawal of any shareholders.

(d) The shareholders present may adjourn the meeting despite the absence of a quorum.