10.1. Infectious diseases
A subsection of Biology, 9700, through 10. Infectious diseases
Listing 10 of 208 questions
Malaria is a serious and often fatal infectious disease caused by Plasmodium. Drugs such as chloroquine are widely used to decrease the risk of getting malaria and also to treat people who have become infected. However, in many parts of the world, Plasmodium populations have become resistant to chloroquine. Sequencing the genome of Plasmodium and the application of bioinformatics has provided several new targets for the development of anti-malarial drugs. Define the term bioinformatics. Outline how sequencing the genome of Plasmodium and the use of bioinformatics can suggest new targets for anti-malarial drugs. In parts of the world where Plasmodium is resistant to chloroquine, one of the most effective anti-malarial drugs currently in use is artemisinin. Artemisinin works by binding to an enzyme in Plasmodium called PfATP6, acting as an inhibitor. A substance called curcumin, which has long been used as a spice and yellow food colouring in India and other countries, is also known to act against chloroquine-resistant Plasmodium. A group of researchers predicted that curcumin acts by binding to the same enzyme as artemisinin. In order to test this hypothesis, and to try to find similar substances that might work even better than curcumin, the researchers used theoretical modelling to: • look at the chemical structures of various molecules with a similar structure to curcumin (curcumin analogues) • generate a three-dimensional model of the structure of the enzyme PfATP6 • investigate whether each curcumin analogue could bind to PfATP6. The researchers predicted that several of the curcumin analogues would bind more strongly than curcumin to PfATP6. Suggest advantages of using theoretical models in this research, rather than testing possible drugs in the laboratory. Suggest why theoretical modelling cannot completely replace laboratory trials in the search for new drugs.
9700_s16_qp_41
THEORY
2016
Paper 4, Variant 1
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Malaria is a serious and often fatal infectious disease caused by Plasmodium. Drugs such as chloroquine are widely used to decrease the risk of getting malaria and also to treat people who have become infected. However, in many parts of the world, Plasmodium populations have become resistant to chloroquine. Sequencing the genome of Plasmodium and the application of bioinformatics has provided several new targets for the development of anti-malarial drugs. Define the term bioinformatics. Outline how sequencing the genome of Plasmodium and the use of bioinformatics can suggest new targets for anti-malarial drugs. In parts of the world where Plasmodium is resistant to chloroquine, one of the most effective anti-malarial drugs currently in use is artemisinin. Artemisinin works by binding to an enzyme in Plasmodium called PfATP6, acting as an inhibitor. A substance called curcumin, which has long been used as a spice and yellow food colouring in India and other countries, is also known to act against chloroquine-resistant Plasmodium. A group of researchers predicted that curcumin acts by binding to the same enzyme as artemisinin. In order to test this hypothesis, and to try to find similar substances that might work even better than curcumin, the researchers used theoretical modelling to: • look at the chemical structures of various molecules with a similar structure to curcumin (curcumin analogues) • generate a three-dimensional model of the structure of the enzyme PfATP6 • investigate whether each curcumin analogue could bind to PfATP6. The researchers predicted that several of the curcumin analogues would bind more strongly than curcumin to PfATP6. Suggest advantages of using theoretical models in this research, rather than testing possible drugs in the laboratory. Suggest why theoretical modelling cannot completely replace laboratory trials in the search for new drugs.
9700_s16_qp_43
THEORY
2016
Paper 4, Variant 3
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is a scanning electron micrograph showing a macrophage engulfing some bacteria. Describe how macrophages engulf bacteria. Explain the functions of lysosomes in cells such as macrophages. shows the reported number of new cases of tuberculosis (TB) in the USA and the number of new cases per 100 000 of the population of the USA between 1993 and 2018. number of new cases per 100 000 population number of new cases per 100 000 population number of new cases Key number of new cases 30 000 25 000 20 000 15 000 10 000 year Calculate the percentage change in the number of new cases of TB in the USA between 1993 and 2018. Show all your working. answer % Use to describe the trend in the number of new cases of TB in the USA between 1993 and 2018. Suggest an advantage of calculating the number of new cases per 100 000 each year in the prevention and control of TB across the world. TB is endemic (always present) in many populations across the world and many countries have high numbers of cases. State two reasons why it is difficult to reduce the number of cases of TB across the world.
9700_w22_qp_23
THEORY
2022
Paper 2, Variant 3
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The malarial pathogen, Plasmodium falciparum, enters red blood cells after a person becomes infected. After some time, each cell of P. falciparum divides to form daughter cells. shows a cell of P. falciparum that is forming many daughter cells. cell surface membrane of red blood cell nucleus With reference to , suggest how the presence of P. falciparum affects a red blood cell. When P. falciparum divides there is unequal division of the cytoplasm to form small, genetically identical daughter cells. Outline the events that occur in the cell of P. falciparum to form the daughter cells shown in . In 2013, the World Health Organization (WHO) set a target for researchers to create a vaccine for malaria. WHO required the vaccine to show 75% efficacy and be ready for use by 2030. Efficacy is a measure of the effectiveness of a vaccine in reducing the number of new cases of malaria. A trial of the R21/Matrix‑MTM vaccine in Burkina Faso in 2020 achieved a 77% efficacy over a 12‑month period. A control group received a vaccine for rabies. Vaccines stimulate an immune response with the production of antibodies. Explain how antibodies will reduce the spread of the malarial pathogen through the bloodstream. Some vaccination programmes have been more successful than others. Discuss the factors that contribute to the success of a vaccination programme.
9700_w23_qp_23
THEORY
2023
Paper 2, Variant 3
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Questions Discovered
208