Pearson Edexcel Level 3 GCE 9BI0/01 2022 Biology B Advanced PAPER 1: Advanced Biochemistry, Microbiology and Genetics

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Answer ALL questions. Some questions must be answered with a cross in a box . If you change your mind about an answer, put a line through the box and then mark your new answer with a cross . 1 The ... pathogenic effects of bacteria can be due to the toxins they release. (a) Endotoxins are released by Gram negative bacteria. (i) Name one type of Gram negative bacteria that releases endotoxins. (1) .................................................................................................................................................................................................................................................................................... (ii) Give one difference between the structure of Gram negative bacteria and Gram positive bacteria. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (b) Endotoxins are usually less toxic than exotoxins. (i) The LD50 value is the mass of the chemical per kg of body mass that would kill half the number of rodent animals. The LD50 value can be used to indicate how toxic a chemical is. One endotoxin has an LD50 value of 11 ng kg–1. The mean body mass of a group of rodents is 28 g. Calculate the mass of endotoxin given to each rodent that would kill half of the rodents in this group. (1 [Show More]

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