Turn over 17 5 (a) (i) Which bonds join the nucleotides in a single strand of DNA? (1) A peptide B disulfide C glycosidic D phosphodiester (ii) Describe how the process of DNA replication produces two identical DNA molecules. (4) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... 18 (b) The graph shows the relationship between genome size and mutation rates of organisms. 1010 109 108 107 106 105 104 103 102 10−11 10−10 10−9 10−8 10−7 10−6 10−5 10−4 10−3 10−2 Genome size / number of nucleotides Mutation rate / substitutions per nucleotide per generation higher eukaryotes lower eukaryotes RNA viruses single stranded DNA viruses double stranded DNA viruses bacteria (i) Analyse the graph to determine the approximate mutation rate for tobacco mosaic virus (TMV). (2) Answer.............................................................. Turn over 19 (ii) Comment on the relationship between genome size and mutation rate of the organisms shown in the graph. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 5 = 10 marks)