Biology · 2014 · November · Paper 2 · HL · Question paper

16 pages N14/4/BIOLO/HP2/ENG/TZ0/XX Monday 10 November 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 8 8 1 4 – 6 0 0 2 [Personal identifier removed] [Personal identifier removed] – 2 – N14/4/BIOLO/HP2/ENG/TZ0/XX 16EP02 SECTION A Answer all questions. Write your answers in the boxes provided. 1. Hypertension (blood pressure exceeding 140 mm Hg) affects millions of people worldwide. Many modern societies consume more sodium in the form of salt (NaCl) than is required for normal physiology. The effect of changing the levels of dietary sodium has been studied in various organisms. Scientists recorded the blood pressure changes in chimpanzees (Pan troglodytes ) fed a diet without added sodium (control) or a sodium supplemented diet (experimental) as follows • 5 grams of salt per day from December 1991 until May 1992 • 10 grams of salt per day until June 1992 • 15 grams of salt per day until August 1993 after which no more salt was added to the diet until the experiment ended. Before Treatment period After Blood pressure / mm Hg 160 150 140 130 120 110 100 Key: control experimental Oct 91Nov 91Dec 91 Jun 92 Mar 93 Aug 93 Nov 93 Mar 94 Time / date [Source: Republished with the permission of the American Society for Clinical Investigation, from K. M. O’Shaughnessy and F. E. Karet (2004) Journal of Clinical Investigation, 113 (8); permission conveyed through Copyright Clearance Center, Inc.] (This question continues on the following page)