14 5 Glandular fever is caused by infection with the Epstein–Barr virus (EBV). The virus infects B lymphocytes and epithelial cells. On infection of these cells, the virus enters the lytic cycle. After the lytic cycle is brought under control by the immune system of the body, latency takes place. (a) The diagram shows the structure of EBV. polyhedral capsid glycoproteins envelope DNA Source from: https://www.hindawi.com/journals/jir/2012/370516/ (i) Which virus has both a polyhedral capsid and an envelope? (1) A Ebola B human immunodeficiency virus C λ (lambda) phage D tobacco mosaic virus (ii) State what the genes in the DNA of EBV code for, other than glycoproteins. (1) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... Turn over 15 (iii) Describe the role of the glycoproteins in EBV. 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(b) Complete the graph to show the shape of the growth curve of EBV as a result of one lytic cycle after infection of a cell. (2) Number of viruses in the cell Time after infection number of viruses on infection 16 (c) An investigation studied a group of 103 children infected with EBV, in one town. The number of children with typical symptoms of EBV infection and the number of children with non-typical symptoms of EBV infection were recorded. The graph shows the results of this investigation. 16 14 12 10 8 6 4 2 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Age / years Number of children with EBV infection Key non-typical symptoms typical symptoms (i) There were 47% boys in this group of children. Calculate the number of girls in this group of children. (2) Answer .............................................................. Turn over 17 (ii) Determine the effect of age on the proportion of children with non-typical symptoms of EBV. (2) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (iii) Describe how this investigation could be improved. (3) .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... .................................................................................................................................................................................................................................................................................... (Total for Question 5 = 13 marks)