Microbial catabolism of phytosterol side chains yields C-19 steroids, C-22 steroids, and 17-ketosteroids (. precursors to adrenocortical hormones and contraceptives ).     The addition and modification of functional groups is key when producing the wide variety of medications available within this chemical classification. These modifications are performed using conventional organic synthesis and/or biotransformation techniques.  
b) British society and culture: Britain and Britishness, stereotypes; the nations of Britain (Scotland, Wales, Northern Ireland, England), English identity; 20th century history; post-colonialism and multicultural Britain; the political system: parliament, the electoral system, government, the monarchy; and judicial system, the legal profession, the police; education: values, the educational system, the curriculum, university; religion, the Church of England, world religions; the media, sport and the arts; home, family, social differences, daily life, leisure, food and drink.