The examination for a license to practice medicine and surgery as an osteopathic physician and surgeon shall cover substantive and clinical knowledge in all the essential branches of medicine and surgery including anatomy, physiology, chemistry, pharmacology, pathology, public health--preventive medicine, surgery, obstetrics and gynecology, osteopathic medicine, materia medica principles and practice of osteopathy. The list of subjects may be expanded or regrouped at the discretion of the board.