Disease & immunity Banker

1. (a) Which type of cell produces antibodies?A red blood cellB phagocyteC lymphocyteD platelet [1]

1. (a) State what is meant by an antigen. [1]
2. (b) Describe two ways in which antibodies help to destroy pathogens. [2]
3. (c) Explain the difference between an antibody and an antibiotic. [2]

1. (a) Explain why antibiotics cannot be used to treat measles or influenza. [2]
2. (b) Explain how a person develops active immunity after recovering from chickenpox. [2]

1. (a) A newborn baby receives antibodies from its mother in breast milk. Which statement is correct?A This is active immunity and lasts for life.B This is passive immunity and no memory cells are made.C This is active immunity because the baby makes memory cells.D This is passive immunity and lasts for life. [1]

Polio vaccination campaigns in Pakistan give drops of vaccine to young children.

1. (a) Describe what a vaccine contains. [2]
2. (b) Describe how vaccination protects a person against polio for a long time. [3]

1. (a) A person bitten by a snake may be given an injection containing ready-made antibodies against the venom. State the type of immunity this gives. [1]
2. (b) Explain why this injection gives immediate protection, but only for a short time. [3]
3. (c) State one natural way in which a fetus gains passive immunity. [1]

1. (a) Why does one type of antibody protect against only one type of pathogen?A each antibody has a shape complementary to one specific antigenB antibodies are made of carbohydrateC each pathogen has the same antigensD antibodies kill pathogens by digesting them [1]

A child was given two doses of a hepatitis B vaccine, five weeks apart. Antibody concentration (arbitrary units) was measured each week after each dose.week after dose | 0 | 1 | 2 | 3 | 4 | 5after first dose | 0 | 2 | 8 | 12 | 6 | 3after second dose | 3 | 40 | 90 | 85 | 70 | 60

1. (a) Calculate how many times higher the peak antibody concentration was after the second dose than after the first dose. [2]
2. (b) Explain why the response to the second dose is faster and greater. [3]
3. (c) State the type of immunity produced by vaccination. [1]

In one region, 9,120,000 out of 9,600,000 children under five were given measles vaccine.

1. (a) Calculate the percentage of children vaccinated. [2]
2. (b) Explain how vaccinating a large percentage of a population also protects people who are not vaccinated. [3]
3. (c) Suggest one reason why some children in a population might not be vaccinated. [1]

1. (a) What is a pathogen?A any microorganismB a disease-causing organismC a chemical that kills bacteriaD a protein made by white blood cells [1]

1. (a) Define the term transmissible disease. [1]
2. (b) Copy and complete the table to give one example of each method of transmission.method | example of how pathogen is passeddirect contact | ?contaminated food | ?animal (vector) | ? [3]

1. (a) State two ways in which hepatitis B virus can be passed from one person to another. [2]
2. (b) Explain why barbers are advised to use a new blade for each customer. [1]

1. (a) Which disease is transmitted mainly through contaminated drinking water?A choleraB influenzaC tuberculosisD measles [1]

1. (a) Explain how each of the following reduces the spread of disease: (i) treating sewage (ii) proper disposal of household rubbish (iii) washing hands before preparing food. [3]
2. (b) Suggest why outbreaks of diarrhoeal disease often follow floods. [2]

1. (a) Malaria is caused by a single-celled organism and transmitted by female Anopheles mosquitoes. Explain what is meant by a vector. [1]
2. (b) Suggest two ways people in rural Sindh can reduce the spread of malaria. [2]

A plate of cooked rice is left in a warm kitchen. It contains 50 bacteria, which divide every 20 minutes.

1. (a) Calculate how many bacteria there would be after 4 hours if none died. [2]
2. (b) Use this information to explain why food such as cooked rice should not be left in a warm kitchen for hours. [2]
3. (c) State one way in which food can be stored to slow down bacterial growth. [1]

1. (a) Tuberculosis (TB) is caused by a bacterium that is spread in droplets when an infected person coughs. Suggest why TB spreads more quickly in crowded housing. [2]
2. (b) Explain why it is important for TB patients to complete their full course of antibiotics. [2]

1. (a) Name the type of organism that causes cholera. [1]
2. (b) Describe how cholera is usually spread. [2]
3. (c) State two ways a city can reduce cholera outbreaks. [2]

A recipe for oral rehydration solution uses 2.6 g of salt (sodium chloride) and 13.5 g of glucose in 1000 cm³ of water.

1. (a) Calculate the mass of salt and the mass of glucose needed to make 250 cm³ of the solution. Give each answer to 2 decimal places. [2]
2. (b) Suggest why the water used to make the solution should be boiled and cooled first. [1]
3. (c) Suggest why a child with cholera can die within a day if not treated. [2]

1. (a) Dengue fever is caused by a virus carried by Aedes mosquitoes. Explain why antibiotics are not given to treat dengue. [1]
2. (b) Aedes mosquitoes breed in small amounts of clean standing water. Suggest two actions a school in Rawalpindi could take to reduce dengue during the monsoon. [2]

1. (a) Typhoid is caused by a bacterium spread in food and water contaminated by faeces. State one symptom that typhoid and cholera may both cause, and explain why this is dangerous. [2]
2. (b) Explain why a person who has recovered from cholera can still pass the disease on. [2]

1. (a) Why does cholera cause severe watery diarrhoea?A The bacterium digests the wall of the large intestine.B A toxin causes chloride ions to be secreted into the small intestine, and water follows by osmosis.C The bacterium uses up water in the gut for its respiration.D A toxin stops the kidneys reabsorbing water. [1]

1. (a) Explain, using the term water potential, how cholera bacteria in the small intestine cause dehydration. [4]
2. (b) Explain why oral rehydration solution contains salts as well as water. [2]

Reported cholera cases in one district:year | number of cases2019 | 12402020 | 8602021 | 6102022 | 29502023 | 720

1. (a) Calculate the percentage increase in cases from 2021 to 2022, to the nearest whole number. [2]
2. (b) Heavy floods occurred in this district in 2022. Suggest why this explains the change. [2]
3. (c) Describe the trend from 2019 to 2021 and suggest one reason for it. [2]

1. (a) Which is a chemical barrier against pathogens?A hairs in the noseB hydrochloric acid in the stomachC the skinD phagocytosis [1]

1. (a) Describe how each of the following helps to prevent pathogens entering the body: (i) skin (ii) mucus in the airways (iii) hairs in the nose. [3]
2. (b) Explain why a deep cut increases the risk of infection. [1]

1. (a) Describe how a phagocyte destroys a bacterium. [3]
2. (b) State one other way in which white blood cells defend the body. [1]

1. (a) Smoking damages the cilia lining the trachea. Explain why smokers get more chest infections. [3]
2. (b) Explain how blood clotting at a wound helps defend against disease. [2]

1. (a) Describe how influenza spreads from person to person, and suggest three measures that could reduce its spread in a school. [5]
2. (b) Explain why a new influenza vaccine is needed most years. [2]

1. (a) Explain why diseases such as cholera and typhoid are much more common where there is no clean water supply or sewage system. [3]
2. (b) A village in Balochistan gets a new well and a simple filter-and-chlorine system. Explain how each part reduces disease. [2]
3. (c) State one way in which the body's own defences protect against swallowed bacteria. [1]