10.1. Infectious diseases
A subsection of Biology, 9700, through 10. Infectious diseases
Listing 10 of 208 questions
An estimated 300 to 500 million cases of malaria occur worldwide each year resulting in 1 to 3 million deaths. 80% of these cases are in children under the age of five. There are four species of malarial parasite, of which Plasmodium falciparum is responsible for most of the deaths from this disease. Describe how the malarial parasite is transmitted. Several potential vaccines against malaria have been developed. Some of these make use of proteins from the surface membrane of P. falciparum. Explain how using such a vaccine may give long-term immunity to malaria. Researchers have been trying to develop a successful vaccine against malaria for about 20 years. Explain why it has proved so difficult to develop such a vaccine. Proteins on the surface of the parasite are responsible for binding to surface receptors on the red blood cells. These are removed when the parasites enter the red blood cells. An enzyme has recently been discovered in P. falciparum that is responsible for the removal of these proteins. If the enzyme does not function then the parasites cannot enter red blood cells. It has been suggested that a drug could be developed to inhibit this enzyme. Describe one possible way in which such a drug might act on the enzyme to prevent it from functioning.
9700_s08_qp_2
THEORY
2008
Paper 2, Variant 0
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Malaria is a disease caused by the parasite, Plasmodium. The parasite has a complex life-cycle, part of which involves development within the gut of the female mosquito which is responsible for the transmission of the disease. shows part of the life-cycle of the malarial parasite. 3. parasite travels to the liver in blood plasma 4. parasite multiplies in the liver and is then transported away inside red blood cells 2. malarial parasite enters blood 1. female mosquito injects malarial parasite into uninfected person Research has been directed towards the development of a malarial vaccine. Much of this research relies on the fact that Plasmodium has different forms in its life cycle. During trials of a malarial vaccine, the parasites were killed using radioactivity and then injected into volunteers. This method provided some protection against malaria. Explain why the parasites were killed using radioactivity and not by using high temperatures. With reference to , explain why the researchers decided to use the form of the parasite which is injected by mosquitoes and not the form which leaves the liver. The volunteers who were injected with the killed parasites produced antibodies, which provided some protection against the disease. Outline the events that occur following injection of the parasites, which lead to the production of antibodies.
9700_s12_qp_23
THEORY
2012
Paper 2, Variant 3
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Questions Discovered
208