Any junior college district is charged with the responsibility for providing preprofessional courses, liberal arts, technical, vocational, and adult education courses and shall undertake to provide the same as conveniently as is possible to the residents of the district, and to this end, the board of trustees is authorized and empowered to transport such enrollees as, in its discretion, should be transported in the best interest of the district. However, no additional allocation of any appropriation shall be made for such transportation. The board of trustees shall promulgate uniform rules to prevent discrimination in all matters of transportation.