Biology · 2009 · November · Paper 2 · HL · Question paper

8809-6002 8 pages N09/4/BIOLO/HP2/ENG/TZ0/XX Tuesday 10 November 2009 (afternoon) Biology HigHER lE vEl Pa PER 2 INSTRUCTIONS TO CANDIDATES • Write your session number in the boxes above. • Do not open this examination paper until instructed to do so. • Section A: answer all of Section A in the spaces provided. • Section B: answer two questions from Section B. Write your answers on answer sheets. Write your session number on each answer sheet, and attach them to this examination paper and your cover sheet using the tag provided. • At the end of the examination, indicate the numbers of the questions answered in the candidate box on your cover sheet and indicate the number of sheets used in the appropriate box on your cover sheet. 2 hours 15 minutes [Personal identifier removed] © International Baccalaureate Organization 2009 0108 88096002 8809-6002 – 2 – N09/4/BIOLO/HP2/ENG/TZ0/XX Section a Answer all the questions in the spaces provided. 1. Type II diabetes is having an impact on the health of many individuals worldwide. The condition is characterized by elevated levels of both insulin and glucose in the bloodstream. Some animals produce an insulin-degrading enzyme (IDE) which breaks down the insulin molecule. In an attempt to develop a model of type II diabetes, genetically modified mice have been developed. In these mice, both copies of the IDE gene have been removed (IDE −−/ ) and the enzyme is not produced. The bar chart below shows the mean concentration of insulin in the bloodstream of IDE −−/ mice and that of control mice (IDE ++/ ). Blood insulin / ng ml–1 2.0 1.5 1.0 0.5 0.0 IDE ++/ IDE −−/ [Source: Wesley Farris et al., “Insulin-degrading enzyme regulates the levels of insulin, amyloid B-protein, and the B-amyloid precursor protein intracellular domain in vivo”, PNAS, 100 (7), pages 4162-7. Copyright 2003 National Academy of Sciences, U.S.A.] ( a) Calculate the percentage increase between mean blood insulin levels in IDE ++/ mice