No person who is otherwise qualified shall be employed in any capacity by the state or any department or agency thereof unless the person is certified as meeting the standards of medical and physical fitness by a qualified medical practitioner within a prescribed number of calendar days after the date of an offer of employment. However, the State Personnel Board may provide for standards of medical and physical fitness for some positions that require only certification by the prospective employee and such certification may be accepted by the respective employing department without further assessment by a medical practitioner.