10.1. Infectious diseases
A subsection of Biology, 9700, through 10. Infectious diseases
Listing 10 of 208 questions
Cholera is an infectious disease that can affect children and adults. Symptoms of the disease can occur very quickly, from a few hours to a few days. Table 4.1 shows: • the economic status of each of five countries • the number of cases of cholera reported to the World Health Organization (WHO) over a five year period for each country • the population in 2006 and in 2010 of each country. Table 4.1 country economic status number of cholera cases reported population / millions Zimbabwe low 12.5297 12.5715 Uganda low 29.3703 33.4247 Angola middle 17.0104 19.0819 Cameroon middle 17.9484 19.5989 Canada high 32.6490 34.1088 Table 4.1 shows that there are differences in the number of cholera cases reported between the high economic status country and the low economic status countries. Suggest three reasons to explain these differences. 1. . 2. 3. With reference to Table 4.1, suggest reasons for the differences in the number of cases of cholera reported over the five year period for Angola and Cameroon. Vaccination helps to prevent the spread of infectious diseases by stimulating an immune response in individuals against specific pathogens, such as Morbillivirus, the virus that causes measles. Suggest two reasons why measles vaccination programmes may fail to prevent epidemics. 1. 2. Outline the response produced by B-lymphocytes on exposure to Morbillivirus in an individual who already has immunity to measles.
9700_w14_qp_22
THEORY
2014
Paper 2, Variant 2
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Drug therapy is the main method of treating cases of malaria. A number of different drugs have been used to kill a species of the Plasmodium parasite that causes malaria. Chloroquine was the main drug used in Africa for many years. In 1996 the newer drug, sulfadoxine- pyrimethamine (Fansidar®), was used instead and the use of chloroquine was discontinued. A study was carried out to estimate the percentage of parasites that were killed by the two different drugs in two countries in Africa. The results of the study are shown in Table 4.1. Table 4.1 country year percentage of parasites killed by chloroquine sulfadoxine- pyrimethamine Kenya Uganda With reference to Table 4.1, describe the difference in effectiveness of the two drugs. Explain how the data in Table 4.1 show evidence that the use of chloroquine was discontinued after 1996. The researchers concluded that in both Kenya and Uganda the parasite had evolved resistance to sulfadoxine-pyrimethamine. Explain how the parasites evolved resistance. The resistance of Plasmodium parasites to chloroquine was found to be due to a difference in the shape of one specific type of cell surface membrane protein. Name the type of variation controlling chloroquine resistance in the Plasmodium population. The life cycle of Plasmodium is very complex, with a number of stages. The stages that infect human beings are haploid. Suggest why the Hardy-Weinberg principle cannot be used to calculate the frequency of the allele for chloroquine resistance.
9700_w16_qp_43
THEORY
2016
Paper 4, Variant 3
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Cells of the immune system function to protect the body against infectious diseases. Name the type of cell that produces antibodies. The virus that causes the infectious disease influenza has two antigens, H and N. Antibodies are produced in response to an infection by this virus. The antibodies are specific for either antigen H or for antigen N. Describe how the structure of an antibody molecule allows it to be specific for one antigen, such as H or N. Cholera is a disease caused by a bacterial pathogen. Name the pathogen that causes cholera. Describe how the pathogen that causes cholera is transmitted. Viruses that infect bacteria are called bacteriophages. Some bacteriophages that infect the cholera pathogen cause lysis of the bacterium. Suggest what happens to the structure of a bacterial cell to cause lysis. Some scientists believe that bacteriophages could be used to treat people who are infected with cholera. Suggest the properties of the bacteriophages that would make this possible. Antibiotics can be used to treat people with cholera. State why antibiotics are not effective against measles.
9700_w17_qp_21
THEORY
2017
Paper 2, Variant 1
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Malaria is a disease transmitted by a vector. State the name of the pathogen that causes malaria. State the name of the vector that transmits the pathogen. In 2014, the World Health Organization (WHO) estimated that 3200 million people were at risk of malaria. This was almost half of the world population in 2014. Table 4.1 shows the number of cases of malaria and the number of deaths from malaria between 1998 and 2013. The table shows numbers for all the countries of the world and for the countries in the WHO African region. The table also shows the numbers in the African region as percentages of the numbers for all countries. Table 4.1 year number of cases of malaria in millions cases in the African region as a percentage of all countries number of deaths from malaria in thousands deaths in the African region as a percentage of all countries all countries African region all countries African region 272.9 237.6 87.1 1110.0 961.0 90.1 236.0 186.6 79.1 872.0 800.0 91.7 225.1 181.0 80.4 747.0 677.0 90.6 198.0 158.4 80.0 584.0 525.6 90.0 Describe the trends shown in Table 4.1. Suggest reasons why the number of cases of malaria and the number of deaths from malaria changed between 1998 and 2013. Malaria is very difficult to control even though there is improved understanding of the disease. Explain why malaria is very difficult to control.
9700_w17_qp_23
THEORY
2017
Paper 2, Variant 3
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shows the human gas exchange system. A B C Name the structures labelled A, B, and C in . A B C Name a non-infectious disease that affects the human gas exchange system. Malaria is an infectious disease. Name the pathogen that causes malaria. There are a number of vaccines being developed to help control the spread of malaria. Explain why vaccination programmes have not been able to eradicate malaria. shows the distribution of malaria in the Americas in 2012. area P = countries where malaria is always present Key area Q = countries where malaria is not present Suggest the factors, other than lack of vaccines, that could be restricting the distribution of malaria to area P.
9700_w18_qp_21
THEORY
2018
Paper 2, Variant 1
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Viruses share common structural features. Some viruses, such as human immunodeficiency virus (H, also have an outer envelope as part of their structure. Outline the key structural features of viruses. HIV can remain in a dormant state within infected immune system cells for many years. A person diagnosed as HIV‑positive (HIV+) has the virus but does not have symptoms of HIV/AIDS. The chances of an HIV+ person developing HIV/AIDS can be greatly reduced with a drug treatment programme known as anti‑retroviral therapy (ART). In 2010, the World Health Organization (WHO) published recommendations for the treatment of pregnant women living with HIV. This includes both HIV+ women and women who have developed HIV/AIDS. The publication recommended that all pregnant and breastfeeding women living with HIV should be provided with ART. shows the number of pregnant women living with HIV, and the number of these receiving ART, between 2005 and 2013, in low and middle income countries. 200 000 400 000 600 000 800 000 1 000 000 1 200 000 1 400 000 1 600 000 1 800 000 2 000 000 total number of pregnant women living with HIV number of pregnant women living with HIV receiving ART Key year number of pregnant women From the data in , it can be calculated that 13% of pregnant women living with HIV received ART in 2005. Calculate the percentage of pregnant women living with HIV that received ART in 2013. answer = % Describe the trends shown in . Suggest and explain the global importance of providing ART to all pregnant and breastfeeding women living with HIV. In a person who has been infected with HIV‑1, the most common strain of HIV, a sample of blood can be tested for the presence of the virus. One test that can only be used in the early stages of infection involves a monoclonal antibody specific for p24, a structural protein present in the virus. is a flow chart outlining the steps in the production of anti‑HIV p24 monoclonal antibody. inject mouse remove cells from mouse spleen step 2 step 3 step 4 step 5 step 6 step 7 step 1 obtain mouse myeloma cells fuse cells from spleen with myeloma cells clone fused cells in a culture medium separate cells and culture in individual wells screen cells to identify desired cells culture desired cells on a large scale State what is being injected into the mouse in step 1. Explain why several weeks, rather than several days, separates step 1 and step 2. State one feature of the myeloma mouse cells, used in step 3, that is essential for this production process. Name the fused cells formed in step 4. Suggest why step 6 is necessary.
9700_w18_qp_22
THEORY
2018
Paper 2, Variant 2
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The bacteria that cause tuberculosis (TB) can be found in many parts of the body including the lungs. State the name of the bacterium that causes TB. The presence of the pathogen in the lungs attracts phagocytes to the area of infection. The phagocytes release elastase, which digests elastin. Many people with TB feel tired all the time. Suggest and explain how the effect of phagocytes on tissues in the lungs leads to people feeling tired all the time. Discuss the biological factors and social factors that make TB a difficult disease to control.
9700_w18_qp_23
THEORY
2018
Paper 2, Variant 3
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Outbreaks of cholera commonly occur in refugee camps that are set up after a major natural disaster such as earthquakes. The list shows some measures that can be taken to limit the spread of cholera in the refugee camps. treating all drinking water supplies with a high concentration of chlorine setting up an emergency treatment centre to isolate cases of cholera and treat them with antibiotics using concentrated disinfectant to clean sewage disposal areas and infected bedding health workers visiting regularly to detect cases keeping good records of the number of cases and deaths at treatment centres Which features of these control measures involve an economic factor?
9700_w19_qp_11
MCQ
2019
Paper 1, Variant 1
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is a transmission electron micrograph showing the bacterial pathogen that causes tuberculosis (TB). Name the pathogen shown in that causes TB. The World Health Organization (WHO) introduced a strategy in 2015 to end the global TB epidemic. An important part of the strategy is to: • identify people at risk of becoming infected with TB • use methods to prevent transmission of TB. The BCG vaccination is one method of prevention recommended for use in countries where TB is common. The BCG vaccine contains a non-pathogenic, living form of the microorganism that causes TB. Complete Table 2.1 by using a tick (✓) to identify the type of immunity that develops in a person who has been given the BCG vaccination. Table 2.1 artificial active immunity artificial passive immunity natural active immunity natural passive immunity Rifampicin is one of the antibiotics used to treat TB. Rifampicin inhibits RNA polymerase in bacterial cells by binding to a site other than the active site. This prevents polypeptide synthesis. Suggest and explain how rifampicin prevents polypeptide synthesis in bacterial cells. Some bacteria have developed resistance to rifampicin. However, they are still susceptible to the other antibiotics that can be used to treat TB. Multi-drug resistant bacteria have developed resistance to at least two drugs, including rifampicin. WHO collects data from all countries on the number of cases of TB caused by rifampicin-resistant bacteria (RR-TB) and multi-drug resistant bacteria (MDR-TB). shows the reported number of cases of TB between 2009 and 2013. 160 000 120 000 80 000 40 000 year reported number of cases of RR-TB and MDR-TB Describe the trend shown by the data in . Explain how resistance to drugs such as rifampicin develops.
9700_w19_qp_21
THEORY
2019
Paper 2, Variant 1
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Questions Discovered
208