OCR GCSE Biology B (Twenty First Century)
OCR GCSE Biology B B2.3 How can we prevent the spread of infections? Exam Questions
Free OCR GCSE Biology B exam questions for B2.3 How can we prevent the spread of infections?, with a mark scheme for every pack. Covers hygiene, sanitation, isolation, vector control, vaccination, herd immunity, antibiotic use and resistance, and preventing plant disease spread.
B2.3 How can we prevent the spread of infections? exam questions
2 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About OCR GCSE Biology B B2.3 How can we prevent the spread of infections?
B2.3 applies your understanding of pathogens and immunity to the problem of stopping disease spreading through populations. You need to describe measures at the level of individuals, communities and countries, such as hygiene, clean water, isolation and controlling vectors, and explain how vaccination works and why high vaccine uptake protects unvaccinated people. Methods to reduce plant disease, such as removing infected plants and controlling movement of plant material, are also included. Examiners often ask you to link a prevention method to a specific route of transmission, or to evaluate a vaccination programme using data.
What you need to know
- Breaking the transmission route Hand washing, disinfecting surfaces, safe food handling and clean water supplies stop pathogens being passed on. Isolating infected people reduces contact spread.
- Vector control Killing or avoiding vectors reduces spread, for example insecticide-treated mosquito nets and draining standing water to reduce malaria.
- Vaccination A vaccine contains dead, inactivated or weakened pathogens, or their antigens. Lymphocytes produce antibodies and memory cells, so on real infection the secondary response destroys the pathogen quickly.
- Herd immunity When a high proportion of a population is vaccinated, the pathogen cannot spread easily, protecting people who cannot be vaccinated.
- Antibiotic resistance Overuse and not finishing courses of antibiotics favour resistant bacteria by natural selection. Prescribing antibiotics only when needed slows resistance spreading.
- Plant disease Spread is reduced by removing and destroying infected plants, crop rotation, controlling insect vectors, and restricting import of plants, as was done for ash dieback.
Common mistakes in B2.3 How can we prevent the spread of infections?
- Saying a vaccine contains antibodies. It contains antigens (from dead or weakened pathogens), which trigger the body to make its own antibodies.
- Stating that antibiotics can treat viral infections like flu. They only affect bacteria.
- Writing that bacteria become resistant because they get used to antibiotics. Resistant variants already exist, survive and reproduce, so the resistant allele becomes more common.
- Thinking herd immunity means everyone is immune. It means enough people are immune to stop the pathogen spreading.
- Giving vague prevention answers such as be clean. Name the method and the transmission route it blocks.
Try three B2.3 How can we prevent the spread of infections? exam-style questions
1. Suggest one way to reduce the spread of a disease carried in water. (1 mark)
Show the mark scheme answer
Treat or chlorinate water, or boil drinking water.
2. In a town of 25 000 people, 23 750 are vaccinated against measles. Calculate the percentage vaccinated. (2 marks)
Show the mark scheme answer
23 750 / 25 000 x 100; = 95%.
3. Explain how vaccinating most of a population protects people who are not vaccinated. (3 marks)
Show the mark scheme answer
Vaccinated people are immune so do not become infected or pass on the pathogen; this reduces the number of possible hosts and chances of transmission; so an unvaccinated person is unlikely to come into contact with the pathogen (herd immunity).
B2.3 How can we prevent the spread of infections? FAQs
What does OCR GCSE Biology B B2.3 cover?
It covers hygiene, clean water, isolation and vector control, how vaccination and herd immunity work, sensible antibiotic use and ways to stop plant diseases spreading.
Which paper is B2.3 examined in?
J257 has two papers at each tier, Breadth in Biology and Depth in Biology, and content from any chapter, including B2, can be assessed on either one. Expect it to be linked to ideas about science and to other chapters.
What is the best way to explain vaccination in an exam?
Say what the vaccine contains, that it triggers lymphocytes to make antibodies and memory cells, and that on later infection antibodies are made faster and in larger amounts.
