10. Infectious diseases
A section of Biology, 9700
Listing 10 of 290 questions
Vaccination can protect against the infectious disease tuberculosis (TB). Define the terms: vaccination infectious disease. TB is an important disease worldwide. Table 2.1 shows recent information about TB cases reported during one year in six different countries. Table 2.1 country region number of cases number of cases per 100 000 population Germany Europe India Asia 2 300 000 Japan Asia 27 000 South Africa Africa 490 000 Swaziland Africa 15 000 United Kingdom Europe With reference to Table 2.1, explain the advantage of calculating the number of cases of TB per 100 000 population rather than stating the number of cases alone. Describe how a person may become infected with TB. Suggest why TB is more likely to be fatal in people who have HIV/AIDS than in those who do not have HIV/AIDS.
9700_s14_qp_23
THEORY
2014
Paper 2, Variant 3
View
Cholera bacteria release the toxin, choleragen, when they are in the intestine. Name the bacterium that is the pathogen of cholera. Describe the way in which cholera is transmitted from an infected person to an uninfected person. Gangliosides are glycolipids that bind choleragen. These glycolipids are found on many cell surface membranes. When choleragen is released from the bacteria in the intestine, it binds to gangliosides on epithelial cells and enters these cells as shown in . intestinal epithelial cell ganglioside choleragen pathogen not drawn to scale Suggest how choleragen interacts with gangliosides on intestinal epithelial cells. Name the process by which choleragen enters the intestinal epithelial cell as shown in . Once inside the cells choleragen is activated. One effect is to increase the movement of chloride ions through channel proteins out of cells. Suggest and explain the likely consequences on the intestinal epithelial cells of the loss of chloride ions through the channel proteins. Health authorities recommend that antibiotics, such as tetracycline, are only to be used for treating people with severe cases of cholera. Explain why it is recommended that antibiotics should not be given to people with mild cases of cholera or to protect people from cholera.
9700_s17_qp_21
THEORY
2017
Paper 2, Variant 1
View
Name the causative organism of tuberculosis (TB). shows the number of deaths from TB and the number of new cases of TB from 1925 to 2010 in Canada. number per 100 000 population year deaths from TB new cases of TB Key The vaccine for TB was introduced in Canada for widespread use from 1948. Antibiotics, such as streptomycin, were introduced in Canada from 1940. Use the information in to comment on the effect of the introduction of the vaccine and antibiotics on the number of new cases and deaths from TB. In 2010, Swaziland had one of the highest death rates from TB in the world. Swaziland also had a high number of new cases of HIV infection in its population in 2010. People who are infected with HIV are described as HIV+ and people who are not infected with HIV are described as HIV–. Table 3.1 shows the number of deaths from TB in Swaziland in 2010. Table 3.1 HIV status number of deaths from TB per 100 000 population HIV+ HIV– Using the information in Table 3.1, suggest why the number of deaths per 100 000 population of people who are HIV+ is much higher than that in people who are HIV–.
9700_s17_qp_23
THEORY
2017
Paper 2, Variant 3
View
The bacterium Vibrio cholerae is the causative organism of the infectious disease cholera. V. cholerae has structural features typical of all bacterial cells. It also has a flagellum for movement. is an outline drawing of V. cholerae. Complete by drawing and labelling the structures found in V. cholerae. flagellum The World Health Organization (WHO) collects data about cholera from the 194 countries that are members of the World Health Assembly (WHA). In 2015: • there were cases of cholera in 42 of the member countries of the WHA • the total number of cases of cholera reported was 172 454 • there were deaths as a result of cholera in 23 of these countries • the total number of deaths from cholera reported was 1304. The case fatality rate for cholera is the proportion of cases of cholera that results in death within a particular time period. A country with cases of cholera that are properly treated should have a case fatality rate of less than 1%. Calculate the case fatality rate for the 42 member countries of the WHA for 2015. Give your answer to the nearest 0.1%. case fatality rate = % Many of the 23 countries reporting deaths from cholera in 2015 had a case fatality rate of less than 1%. However, two of the 23 countries had case fatality rates greater than 5%. Suggest two explanations for the higher case fatality rate in these two countries. In 2010, the country of Haiti experienced a major earthquake. This led to an outbreak of cholera. Explain why an earthquake may lead to a cholera outbreak. shows data about cholera collected by WHO over a period of 8 years, from 2008 to 2015. These data include: • the total number of cases of cholera for each year • the number of countries in each year that had cases of cholera. 100 000 200 000 300 000 400 000 500 000 600 000 700 000 number of countries number of cases year Key number of cases number of countries Comment on the trends shown in .
9700_s19_qp_22
THEORY
2019
Paper 2, Variant 2
View
Questions Discovered
290