Biology · 2008 · November · Paper 2 · HL · Question paper

8808-6002 9 pages N08/4/BIOLO/HP2/ENG/TZ0/XX+ Monday 17 November 2008 (afternoon) Biology Hig HER l Ev El 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 2008 0109 88086002 8808-6002 – 2 – N08/4/BIOLO/HP2/ENG/TZ0/XX+ Section a Answer all the questions in the spaces provided. 1. The influence of plant volatiles (airborne chemicals released by plants) on other plants was investigated using dodder (Cuscuta pentagona). Dodder is a vine-like weed with no leaves and little photosynthetic ability. It robs other plants of their nutrients by attaching to their shoots and leaves above ground. In a series of experiments, 30 newly germinated dodder seedlings were placed at the centre of a damp filter paper disc. A potential target was positioned near the edge of the disc. Seedlings were allowed to grow for four days. Seedlings’ growth across the disc was then recorded by tracing their location on the filter paper. Results for experiments are shown in the diagrams below. The black dots represent the final positions to which the seedlings grew. Figure 1: Filter paper showing results of dodder seedling growth responses Filter paper results experiment 1 experiment 2 experiment 3 Target moist soil 20-day-old tomato plant cotton saturated with tomato volatiles Tracings of seedling growth responses Target Position    Tracing counts of disc halves 16 14 6 24 8 22