Ms.G's Science and Beyond!



6.1 Digestion IB Bank & Paper 2 QuestionsQUESTION 1)Helicobacter pylori is able to live inside the stomach wall of humans. This bacterium can cause inflammation of the stomach wall (gastritis). There may be a link between H. pylori and the development of stomach cancer.The graph below shows the blood levels of antibodies resulting from H. pylori infection for a control group without stomach cancer and a group with stomach cancer. The solid lines show the median concentrations for the control group and the group with stomach cancer.Antibody concentrations above 10 μg ml–1 indicate that there has been infection with H. pylori.[Source: Forman, D. 1991. “Association between infection with Helicobacter pylori and risk of gastric cancer: evidence from a prospective investigation”. British Medical Journal. Vol 302. Pp 1302–1305.](a)47 % of the control group had been infected with H. pylori. Calculate the percentage of the group with stomach cancer that had been infected. Show your working.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(b)Using all of the data, evaluate the hypothesis that H. pylori causes stomach cancer.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(c)A study in gerbils indicated that infection with H. pylori leads to a decrease in the secretion of hydrochloric acid. Discuss the consequences of this finding for the digestion of proteins in the stomach in humans.........................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(2)(Total 7 marks)QUESTION 2) In North America normal diets are traditionally low in fibre. Scientists have proposed the hypothesis that people with diabetes benefit from a high fibre diet. The diagrams show the effect on blood glucose and blood insulin concentrations of a group of diabetic patients fed on a high fibre diet compared to a group of diabetic patients fed on a normal diet. The bars indicate standard error.[Source: M Chandalia, et al., The New England Journal of Medicine, (2000), 342, pages 1392?1398](a)(i)Deduce, with a reason, what occurred at the times indicated by the arrows.......................................................................................................................................................................................................................................................(1)(ii)State the lowest blood glucose concentration in the normal diet.......................................................................................................................................................................................................................................................(1)(b)Compare the variation, over a 24 hour period, in both the blood glucose and insulin concentrations in the high fibre group................................................................................................................................................................................................................................................................................................................................................................................................................(2)(c)Evaluate the effect of the high fibre diet on lowering blood glucose and insulin levels in the two groups.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................(3)(Total 7 marks) ................
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