Biology · 2014 · May · Paper 2 · HL · TZ1 · Question paper

20 pages M14/4/BIOLO/HP2/ENG/TZ1/XX Friday 9 May 2014 (afternoon) BIOLOGY HIGHER LEVEL PAPER 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 questions. • Section B: answer two questions. • Write your answers in the boxes provided. • A calculator is required for this paper. • The maximum mark for this examination paper is [72 marks]. 2 hours 15 minutes © International Baccalaureate Organization 2014 Examination code 2 2 1 4 – 6 0 0 8 [Personal identifier removed] [Personal identifier removed] – 2 – M14/4/BIOLO/HP2/ENG/TZ1/XX 20EP02 SECTION A Answer all questions. Write your answers in the boxes provided. 1. Proteasomes are a group of proteins that destroy unwanted proteins in the cell, thereby maintaining cell health. However, chemical inhibitors can block the action of proteasomes, resulting in a build up of unwanted proteins with negative consequences for the cell. Rat heart cells were incubated at different concentrations of a proteasome inhibitor in order to test its toxicity. The bar graph shows the percentage survival of these cells compared to untreated control cells. Survival / % of control cells 100 90 80 70 60 50 40 30 20 10 0 0 5 7.5 10 20 Proteasome inhibitor concentration / nmol dm–3 [Source: Adapted from Nowis et al. (2010) American Journal of Pathology, 176 (6). Pages 2658--2668. ‘Cardiotoxicity of the Anticancer Therapeutic Agent Bortezomib’, with permission from Elsevier.] (a) State the percentage survival of heart cells treated with 20 nmol dm–3 proteasome inhibitor. [1] . . . . . . . . . . . . . . . . . . . % (This question continues on the following page)