The city council shall provide by ordinance for such boards and commissions as may be required by law or deemed desirable, shall prescribe their functions, and may prescribe qualifications and conditions of service on such boards and commissions, including compensation and reimbursement for expenses, terms or office, method of appointment and removal. Except as otherwise expressly provided in this Charter, the mayor shall appoint all members of boards and commissions, subject to the concurrence of a majority of the city council.