11. Immunity
A section of Biology, 9700
Listing 10 of 303 questions
Many tumours release a protein growth factor called VEGF. This is a chemical signal that causes nearby blood vessels to grow new branches into the tumour. The monoclonal antibody, bevacizumab (Avastin®), specifically binds to VEGF. Suggest how Avastin® can prevent the growth and spread of a tumour. Avastin® is made by the hybridoma method. State: the antigen that is injected into a mouse to produce this monoclonal antibody what is meant by a hybridoma. The monoclonal antibody made by the hybridoma method is modified to obtain humanised mouse antibody. This type of antibody molecule resembles those produced by humans. Suggest advantages of using humanised mouse antibody rather than mouse antibody. A second monoclonal antibody, ranibizumab (Lucentis®) is used to treat eye diseases. Lucentis® is a fragment of Avastin® and is shown in . antigen binding site Complete to show a molecule of Avastin®. Labels are not required.
9700_w14_qp_41
THEORY
2014
Paper 4, Variant 1
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Many tumours release a protein growth factor called VEGF. This is a chemical signal that causes nearby blood vessels to grow new branches into the tumour. The monoclonal antibody, bevacizumab (Avastin®), specifically binds to VEGF. Suggest how Avastin® can prevent the growth and spread of a tumour. Avastin® is made by the hybridoma method. State: the antigen that is injected into a mouse to produce this monoclonal antibody what is meant by a hybridoma. The monoclonal antibody made by the hybridoma method is modified to obtain humanised mouse antibody. This type of antibody molecule resembles those produced by humans. Suggest advantages of using humanised mouse antibody rather than mouse antibody. A second monoclonal antibody, ranibizumab (Lucentis®) is used to treat eye diseases. Lucentis® is a fragment of Avastin® and is shown in . antigen binding site Complete to show a molecule of Avastin®. Labels are not required.
9700_w14_qp_42
THEORY
2014
Paper 4, Variant 2
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A student was asked to explain why vaccination has successfully eradicated smallpox but not other diseases, such as measles, malaria and sickle cell anaemia. These are the statements made by the student. The antigens of the virus causing smallpox did not change, unlike the antigens of the virus causing measles. Sickle cell anaemia has many different types of mutation, unlike smallpox, so each would require a vaccine. Unlike smallpox, malaria involves animals as part of the transmission cycle and this makes the cycle harder to break. The vaccine against measles often causes a poor primary immune response so that booster vaccines are required, unlike the vaccine against smallpox. Which statements are possible explanations?
9700_m20_qp_12
MCQ
2020
Paper 1, Variant 2
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Myasthenia gravis and HIV/AIDS both involve disorders of the immune system. Outline why myasthenia gravis is described as a disorder of the immune system. A person with HIV/AIDS has a weakened immune system. This is because HIV infects cells of the immune system, in particular T‑helper lymphocytes (Th cells). The pathogen can remain inactive within host cells. In some people, the pathogen becomes active and causes the number of Th cells to decrease. Antiretroviral therapy (ART) is used to treat people who are infected with HIV (living with H. ART aims to keep the number of Th cells at a healthy level. State the full name of the pathogen known as HIV. Explain why it is important that ART maintains a healthy number of Th cells in a person living with HIV. shows global estimates of: • the percentage of people living with HIV who received treatment with ART in each year from 2000 to 2015 • the number of people who died from HIV/AIDS in each year from 2000 to 2015. 0.0 year percentage of people living with HIV who received treatment key number of deaths from HIV/AIDS number of deaths from HIV/AIDS / millions percentage of people living with HIV who received treatment 0.5 1.0 1.5 2.0 2.5 Describe the trends shown in . It is recommended that ART is given to all people living with HIV. Some countries that support this recommendation find it difficult to provide ART to everyone living with HIV. Other than the high cost of treatment, suggest two reasons why it is difficult to provide ART to everyone living with HIV.
9700_m20_qp_22
THEORY
2020
Paper 2, Variant 2
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Questions Discovered
303