10. Infectious diseases
A section of Biology, 9700
Listing 10 of 290 questions
State the name of the organism that causes cholera. NQR is an important respiratory enzyme located in the cell surface membrane of the bacterium that causes cholera. A student suggested that an inhibitor of the enzyme NQR could be used as a drug in the prevention and control of cholera. Suggest and explain how this inhibitor would function. Table 5.1 shows the statistics for cholera reported to the World Health Organization (WHO) in four regions of the world in 2008. Table 5.1 region number of cases number of deaths fatality rate / % Africa 179 323 5 074 2.83 Asia 10 778 0.64 Europe 0.00 North America 0.00 Total 190 130 5 143 Calculate the total cholera fatality rate for 2008. Show your working. answer % Apart from differences in total population size in each of the regions, suggest explanations for the differences shown in Table 5.1.
9700_s12_qp_22
THEORY
2012
Paper 2, Variant 2
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Cholera is a disease caused by the bacterium Vibrio cholerae. The disease symptoms are caused by a toxin, produced by the bacterium, interacting with proteins in the cell surface membranes of epithelial cells in the human intestine. The cholera toxin is a protein and is composed of two subunits, A and B. Subunit A is made from one polypeptide and subunit B is made from five identical polypeptides. shows the structure of the cholera toxin. subunit A subunit B S Name: the level of structure that is only shown by a protein that has more than one polypeptide chain the part labelled S. The cholera toxin interacts with ion channels in the epithelial membranes, resulting in watery diarrhoea. These channels open, allowing ions to move from the epithelial cells into the lumen of the intestine. Name the process by which the ions move in this case. Due to the movement of ions into the lumen, water moves from the epithelial cells into the lumen. Name the process by which water moves and explain why it moves into the lumen. name explanation Large outbreaks of cholera are often associated with natural disasters. For example, following an earthquake in Pakistan in 2005, an estimated 20 000 cholera cases were reported in the vicinity, compared to approximately 1000 cases in the rest of the country. Describe the mode of transmission of cholera. Explain how natural disasters can sometimes result in transmission to more individuals.
9700_s12_qp_23
THEORY
2012
Paper 2, Variant 3
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Explain why tuberculosis (TB) is known as an infectious disease. Outline the role of antibiotics in the treatment of infectious diseases, such as TB. Tobacco smoking is a risk factor for a number of diseases. This means that it increases the risk of developing disease. In 2009, the World Health Organization (WHO) published a factsheet stating that tobacco smoking: • may be responsible for more than 20% of the new cases of TB globally • increases the risk of becoming infected and having active TB • increases the risk of dying from TB • is a risk factor for TB in all socioeconomic groups. Projects have been set up in a number of different countries to tackle this health problem. One project involves health workers encouraging TB patients to give up smoking. Suggest what epidemiological evidence would lead to the conclusion that tobacco smoking is a risk factor for TB. Suggest and explain how the effects of smoking can increase the risk of becoming infected with TB. Many smokers know that tobacco smoking is a risk factor for coronary heart disease, but continue to smoke. Some of these smokers have stated that they expect medical practitioners to cure them if they develop coronary heart disease. List two treatments used by medical practitioners to treat coronary heart disease. 1. 2.
9700_s13_qp_22
THEORY
2013
Paper 2, Variant 2
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Vibrio cholerae is a prokaryotic organism. shows the structure of a cell of V. cholerae. 3.0 +m G F E D C A B capsule Calculate the magnification of . Show your working and give your answer to the nearest whole number. magnification × Locate the structures in that apply to each of the features shown in Table 1.1. Complete Table 1.1 by writing the appropriate letter and the name of the structure. You must only give one letter in each case. You may use each letter once, more than once or not at all. The first answer has been completed for you. Table 1.1 feature identity name provides motility F flagellum stores genetic information partially permeable composed of murein site of translation State three structural features that are present in a mesophyll cell in a leaf that are not present in a prokaryotic cell such as that of V. cholerae. 1. 2. 3. Describe how V. cholerae is transmitted from an infected person to an uninfected person. It is important to know how pathogens are transmitted in order to develop effective control methods. Explain how this knowledge is used to control the spread of V. cholerae in the human population.
9700_s14_qp_21
THEORY
2014
Paper 2, Variant 1
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Table 4.1 shows some information about five infectious diseases. Table 4.1 infectious disease name of causative organismtype of causative organism main mode of transmission HIV/AIDS human immunodeficiency virus (Hvirus sexual contact cholera Vibrio cholerae ingestion of contaminated water and food tuberculosis Mycobacterium tuberculosis bacterium measles virus aerosol / droplet infection Plasmodium vivax or P. malariae or P. falciparum or P. ovale Complete Table 4.1. In 2011, the World Health Organization (WHO) published recommendations to help countries develop plans to prevent the spread of HIV. Discuss the factors that should be considered when making recommendations concerning the prevention of sexual transmission of HIV. HIV infects cells of the immune system, particularly helper T-lymphocytes (Th cells). HIV can infect both non-dividing and dividing helper T-lymphocytes, including memory cells. The onset of disease, which can occur many years later, coincides with a severely lowered primary and secondary immune response, owing to greatly reduced numbers of Th cells in the body. An infected Th cell can still carry out a normal cell cycle and divide to produce two cells. The following processes occur during one cell cycle: DNA replication mitosis growth cytokinesis List the processes in a correct sequence. 1. 2. 3. 4. Suggest and explain how the destruction of memory Th cells will contribute to a lowered secondary immune response.
9700_s14_qp_22
THEORY
2014
Paper 2, Variant 2
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Questions Discovered
290