Biology · 2006 · May · Paper 3 · HL · TZ1 · Question paper

2206-6009 20 pages M06/4/BIOLO/HP3/ENG/TZ1/XX Friday 5 May 2006 (morning) biology higher level PaPer 3  IB DIPLOMA PROGRAMME PROGRAMME DU DIPLÔME DU BI PROGRAMA DEL DIPLOMA DEL BI INSTRUCTIONS TO CANDIDATES • Write your session number in the box above. • Do not open this examination paper until instructed to do so. • Answer all of the questions from two of the Options in the spaces provided. You may continue 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 letters of the Options answered in the candidate box on your cover sheet and indicate the number of answer sheets used in the appropriate box on your cover sheet. 1 hour 15 minutes [Personal identifier removed] 0120 22066009 2206-6009 – 2 – M06/4/BIOLO/HP3/ENG/TZ1/XX option D — evolution D1. The cyanobacterial genus Synechococcus is found in hot springs. Five strains (Synechococcus strain 1 to 5) were isolated from a hot spring in Oregon (USA) and tested for tolerance to high temperatures. The phylogeny in the figure below shows one common ancestor and relationships between the five strains. The growth rates of each of these five strains were determined at different temperatures. Synechococcus strain 1 Synechococcus strain 2 Synechococcus strain 3 Synechococcus strain 4 Synechococcus strain 5 growth rate / arbitary units day–1 growth rate / arbitary units day–1 growth rate / arbitary units day–1 growth rate / arbitary units day–1 growth rate / arbitary units day–1 Temperature / °C [Source: S Miller and R W Castenholz, Application and Environmental Microbiology, (2000), 66, pages 4222–4229] (This question continues on the following page) Common Ancestor 0220