Papua New Guinea’s constitution was adopted in 1975 and has been amended frequently since then. The country is a constitutional monarchy and a member of the Commonwealth. The British monarch, represented by a governor-general, is head of state, and the prime minister is head of government. The unicameral National Parliament has 111 members who are elected to serve five-year terms. Of those, 89 represent single-member “open” electorates (districts); each of the other 22 represents one of the provincial electorates. Parliament nominates the governor-general, who is then appointed by the British monarch. Parliament also elects the prime minister, who in turn appoints the ministers of the National Executive Council (cabinet).