O Level Biology 5090 · Topic 12

Disease and immunity: past paper questions

167 real questionsasked in 9 of the last 10 exam series2019–2025usually: Suggest, Explain, State, Describe, Name

Real questions on disease and immunity

The newest 20 of 65 written questions, plus 102 multiple-choice. Open one to see it on the real paper.

5090/21 · October/November 2025 · Q1c(iii)[3]
When a man and a woman are unable to have children, they are said to be an infertile couple. There are estimated to be 90 million infertile couples in the world. There are many causes of infertility but 17% of cases are due to blocked tubes in women. Calculate the number of couples in the world whose infertility is due...
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5090/21 · October/November 2025 · Q7a(i)[2]
Put ticks ( ✓ ) in Table 7.1 to show the characteristics of each pathogen. Table 7.1 characteristic HIV MRSA contains cytoplasm contains genetic material has a protein coat is a living cell
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5090/21 · October/November 2025 · Q7a(ii)[3]
Describe how HIV affects the human immune system.
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5090/21 · October/November 2025 · Q7a(iii)[2]
For different reasons, HIV and MRSA are not destroyed by antibiotics such as penicillin. Give these reasons. MRSA HIV
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5090/21 · October/November 2025 · Q7b[3]
Fig. 7.1 shows the number of people infected by the MRSA pathogen in different countries. It also shows the total amount of antibiotics used in each country in one year per 1000 people. South Korea Spain number of people infected by the MRSA pathogen United States Canada Netherlands Great Britain Germany 0 0 amount of...
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5090/22 · October/November 2025 · Q5b[4]
The ABO blood groups in humans are determined by three alleles, I A , I B and I O . There are four blood groups (phenotypes) but six different genotypes for the ABO blood groups. Complete Table 5.1 to match the blood groups to their possible genotypes. Table 5.1 blood group (phenotype) possible genotype(s) A B AB O
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5090/22 · October/November 2025 · Q5c(i)[1]
State the genotype of the fetus.
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5090/22 · October/November 2025 · Q5c(ii)[3]
The woman and the fetus have different blood groups so they have different antigens on their red blood cell membranes. The woman has antibodies to the antigens on the red blood cell membranes of the fetus. Explain why the woman’s antibodies are not usually able to come into contact with the antigens of the fetus.
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5090/22 · October/November 2025 · Q6a(ii)[3]
Suggest and explain reasons why outbreaks of cholera are more likely after natural disasters.
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5090/21 · May/June 2025 · Q4a[2]
Draw a line from each transmissible disease to the type of pathogen that causes the disease. transmissible disease type of pathogen AIDS bacterium cholera virus malaria protoctist
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5090/21 · May/June 2025 · Q4b(i)[3]
Complete these sentences about cholera by writing words in the gaps. When the cholera pathogen is inside the small intestine it produces a This results in the secretion of ions into the small intestine. The water potential inside the small intestine will , causing .
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5090/21 · May/June 2025 · Q4b(ii)[2]
In 2017 the World Health Organization estimated that 95 000 people die from cholera each year. The World Health Organization set up a project to reduce this number of deaths by 95% by 2030. If the project is successful, calculate the maximum number of cholera deaths in 2030. Space for working. maximum number of cholera...
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5090/21 · May/June 2025 · Q4b(iii)[4]
The World Health Organization recommends vaccines to protect people from cholera. Describe how vaccination can make people immune to a disease.
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5090/21 · May/June 2025 · Q4b(iv)[3]
Table 4.1 shows details of a vaccine used by the World Health Organization to protect people from cholera. Table 4.1 doses needed how taken storage temperature for vaccine two doses, one to six weeks apart vaccine added to a glass of water 2– 8 °C Discuss the practical problems of using this vaccine in different parts...
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5090/22 · May/June 2025 · Q3a(iii)[3]
Antibodies can destroy bacterial cells without destroying human cells. Explain how this is possible.
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5090/22 · May/June 2025 · Q3b(i)[1]
Suggest why this is called a disc diffusion test.
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5090/22 · May/June 2025 · Q3b(ii)[1]
Describe what these results show about the effectiveness of antibiotics 1 and 5. antibiotic antibiotic
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5090/22 · May/June 2025 · Q3c(i)[1]
Suggest which strain, K, L, M or N, in Fig. 3.2 is likely to become the largest percentage of the population.
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5090/22 · May/June 2025 · Q3c(ii)[5]
Explain why the strain named in (c)(i) is likely to become the largest percentage of the population over time.
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5090/21 · October/November 2024 · Q7a[7]
Explain how long-term active immunity develops in the human body after infection by a pathogen.
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What examiners said

Most candidates appreciated how disease was transmitted. However, many did not score a mark as they referred to diseases or germs being present in droplets rather than pathogens or a named type of pathogen.
— Examiner report, October/November 2023, 5090/21 Q4(a)(ii) (Cambridge)

Again, many candidates achieved three or four marks on this question. There were general points made about avoiding extinction and protecting biodiversity. Then candidates suggested methods to achieve this such as education, legal restrictions on hunting and protection of habitats.
— Examiner report, October/November 2023, 5090/21 Q8(b) (Cambridge)

Many candidates knew that ‘pathogen’ is the term for a disease-causing organism. Those who did not give this term were most likely to opt for naming a type of organism that can cause disease such as a bacterium or virus. A common mistake was to suggest the term ‘parasite’.
— Examiner report, October/November 2023, 5090/22 Q1(a)(i) (Cambridge)

Practise this topic

Answer these questions online and get each one marked against the official mark scheme, with what you missed and how to fix it.

Practise disease and immunity

In the syllabus

12.1 Disease

Describe a pathogen as a disease-causing organism
Describe a transmissible disease as a disease in which the pathogen can be passed from one host to another
Understand that a pathogen may be transmitted: (a) through direct contact, including through blood or other body fluids (b) indirectly, including from contaminated surfaces or food, from animals, or from the air
Describe the human body’s barriers to the entry of pathogens, limited to: skin, hairs in the nose, mucus, stomach acid
Understand the role of the mosquito as a vector of disease
Describe the malarial pathogen as an example of a parasite and explain how it is transmitted
Describe the control of the mosquito that transmits malaria with reference to its life cycle
Explain that human immunodeficiency virus (HIV) is a viral pathogen
Describe how HIV is transmitted
Understand that HIV infection may lead to Acquired Immune Deficiency Syndrome (AIDS)
Describe the methods by which HIV may be controlled
Describe cholera as a disease caused by a bacterium, which is transmitted in contaminated water

12.2 Antibiotics

Describe a drug as any substance taken into the body that modifies or affects chemical reactions in the body
Describe the use of antibiotics for the treatment of bacterial infection
State that antibiotics kill bacteria but do not affect viruses
Explain how development of antibiotic-resistant bacteria, including MRSA, can be minimised by using antibiotics only when essential

12.3 Immunity

Describe active immunity as defence against a pathogen by antibody production in the body
State that each pathogen has its own antigens, which have specific shapes
Describe antibodies as proteins that bind to antigens leading to direct destruction of pathogens, or marking of pathogens for destruction by phagocytes
State that specific antibodies have complementary shapes which fit specific antigens
Explain that active immunity is gained after an infection by a pathogen, or by vaccination
Outline the process of vaccination: (a) weakened pathogens or their antigens are given (b) the antigens stimulate an immune response by lymphocytes which produce antibodies (c) memory cells are produced that give long-term immunity
Explain the role of vaccination in controlling the spread of transmissible diseases
Explain that passive immunity is a short-term defence against a pathogen by antibodies acquired from another individual, limited to: across the placenta and in breast milk
Explain the importance of breast-feeding for the development of passive immunity in infants
State that memory cells are not produced in passive immunity
Outline how HIV affects the immune system, limited to: decreased lymphocyte numbers and reduced ability to produce antibodies, which weakens the immune system

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