Cambridge IGCSE Biology
Cambridge IGCSE Biology 10 Diseases and Immunity Exam Questions
Free Cambridge IGCSE Biology revision for 10 Diseases and Immunity: what you need to know, common mistakes and exam-style questions with answers. Covers pathogens and transmissible diseases, transmission routes, body defences, controlling spread, antibodies, active and passive immunity, vaccination and cholera.
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About Cambridge IGCSE Biology 10 Diseases and Immunity
Diseases and immunity explains how pathogens spread and how the body defends itself in Cambridge IGCSE Biology. Core candidates define a pathogen and a transmissible disease, describe direct and indirect transmission, list the body's defences, and explain how clean water, hygiene, waste disposal and sewage treatment control spread. Extended candidates go further into antigens and antibodies, active and passive immunity, memory cells, how vaccination works and why cholera causes diarrhoea. Examiners often ask for a sequenced account of vaccination or of the immune response, and the correct terms matter: antibodies are specific to an antigen, and lymphocytes produce them.
What you need to know
- Pathogens and transmission A pathogen is a disease-causing organism. A transmissible disease is one in which the pathogen can be passed from one host to another. Transmission is direct (blood, other body fluids) or indirect (contaminated surfaces, food, animals, air).
- Body defences Mechanical barriers such as skin and hairs in the nose; chemical barriers such as mucus and stomach acid; and cells, by phagocytosis and antibody production. Vaccination also gives protection.
- Controlling spread Clean water supply, hygienic food preparation, good personal hygiene, waste disposal and sewage treatment all reduce transmission.
- Antibodies and antigens (Extended) Antibodies are proteins that bind to antigens, leading to direct destruction of pathogens or marking them for destruction by phagocytes. Each pathogen has its own antigens with specific shapes, so specific antibodies are needed.
- Active immunity and vaccination (Extended) Active immunity is defence against a pathogen by antibody production in the body, gained after infection or vaccination. A vaccine contains weakened pathogens or their antigens; lymphocytes produce specific antibodies and memory cells give long-term immunity. Vaccination controls spread through herd immunity.
- Passive immunity and cholera (Extended) Passive immunity is short-term defence by antibodies acquired from another individual, for example across the placenta or in breast milk; no memory cells are made. Cholera bacteria release a toxin that causes secretion of chloride ions into the small intestine, lowering water potential, so water moves into the gut by osmosis, causing diarrhoea and dehydration.
Common mistakes in 10 Diseases and Immunity
- Saying antibodies kill bacteria by eating them. Phagocytes engulf pathogens; antibodies bind to antigens.
- Saying a vaccine contains antibodies. A vaccine contains weakened pathogens or antigens that stimulate the body to make its own antibodies.
- Saying passive immunity is long-term. No memory cells are produced, so it is short-term.
- Saying antibiotics work against viruses. Antibiotics act only on bacteria.
- Using 'germs' or 'bugs'. Use the term pathogen.
Try three 10 Diseases and Immunity exam-style questions
1. Define the term pathogen. (1 mark)
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A disease-causing organism.
2. Explain how vaccination gives long-term protection against a disease. (4 marks)
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Vaccine contains weakened pathogens or their antigens; lymphocytes produce specific antibodies; memory cells are produced; on later infection memory cells produce antibodies faster and in greater quantities so the pathogen is destroyed before symptoms develop.
3. Explain how the cholera toxin causes diarrhoea. (3 marks)
Show the mark scheme answer
Toxin causes secretion of chloride ions into the small intestine; this lowers the water potential in the gut; water moves out of the blood into the gut by osmosis, causing loss of water (diarrhoea and dehydration).
10 Diseases and Immunity FAQs
What does Cambridge IGCSE Biology 10 Diseases and Immunity cover?
It covers pathogens and how transmissible diseases spread, the body's defences and ways to control spread, and for Extended candidates antibodies, active and passive immunity, vaccination and cholera.
Which paper is 10 Diseases and Immunity examined in?
It is examined in the theory and multiple choice papers: Papers 1 and 3 for Core candidates, or Papers 2 and 4 for Extended candidates. Practical skills linked to it can also appear in Paper 5 (Practical Test) or Paper 6 (Alternative to Practical).
What is the difference between active and passive immunity?
Active immunity is when your own lymphocytes make antibodies and memory cells after infection or vaccination, so it is long-lasting. Passive immunity is receiving ready-made antibodies, for example from breast milk, so it is short-term because no memory cells are made.
