How do vaccines protect us, why is antibiotic resistance a problem, and how are monoclonal antibodies and new drugs developed?
How vaccination produces immunity and memory cells, the use and limits of antibiotics and the rise of antibiotic resistance, the production and uses of monoclonal antibodies, and the discovery and testing of new medicines.
A focused answer to the WJEC GCSE Biology section 2.8 topic on treatment, covering vaccination and memory cells, the use and limits of antibiotics, antibiotic resistance and MRSA, the production and uses of monoclonal antibodies, and the discovery and testing of new medicines through preclinical and clinical trials.
Reviewed by: AI editorial process; not yet individually human-reviewed
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What this dot point is asking
WJEC wants you to know how vaccination produces immunity and memory cells, how antibiotics work and why resistance arises, how monoclonal antibodies are produced and used, and how new medicines are discovered and tested.
Vaccination and immunity
A vaccine contains dead or inactive forms of a pathogen, or its antigens. Because the pathogen is harmless, it does not make you ill, but its antigens still trigger the immune response.
- The vaccine introduces the antigens into the body.
- Lymphocytes recognise the antigens and produce the correct antibodies.
- The body also makes memory cells.
- If the live pathogen enters the body later, the memory cells make the right antibodies quickly and in large numbers, so the person does not become ill.
Vaccinating most of a population gives herd immunity, making it hard for the disease to spread. Vaccination programmes raise issues to weigh up, including possible side effects, cost and ethical concerns, against the benefit of preventing disease.
Antibiotics and resistance
Antibiotics are medicines that kill bacteria inside the body. They do not work against viruses, because viruses reproduce inside the body's own cells.
The overuse and misuse of antibiotics has led to the evolution of antibiotic-resistant bacteria:
- By chance, a random mutation makes some bacteria resistant to an antibiotic.
- When the antibiotic is used, the non-resistant bacteria are killed, but the resistant ones survive.
- The resistant bacteria reproduce and pass on the resistance.
- Over many generations the resistant strain becomes common. An example is MRSA.
Resistance can be slowed by only using antibiotics when needed, completing the full course, and restricting their use in agriculture.
Monoclonal antibodies
Monoclonal antibodies are large numbers of identical antibodies, all specific to one antigen.
Their specificity makes them useful in medicine, including:
- Diagnosis of diseases, including chlamydia and HIV.
- Tissue typing before transplants.
- Monitoring the spread of malaria.
- Supporting chemotherapy for some cancers.
Discovering and testing new medicines
New medicines must be found and then tested thoroughly before they are used, because they may have side effects. Testing happens in stages:
- Preclinical testing: the drug is tested first on human cells grown in the laboratory and then on animals.
- Clinical testing: the drug is then tested on a small group of healthy volunteers to check it is safe, and then on patients to check it works and to find the right dose.
Only after this rigorous, large-scale testing can a medicine be approved for general use.
Exam-style practice questions
Practice questions written in the style of WJEC exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
WJEC style4 marksExplain how a vaccine produces long-term immunity to a disease.Show worked answer →
A 4-mark explain question on vaccination.
A vaccine contains dead or inactive forms of a pathogen, which carry its antigens. The antigens stimulate the lymphocytes to produce the correct antibodies. The body also makes memory cells. If the live pathogen later enters the body, the memory cells recognise the antigen and produce the right antibodies quickly and in large numbers, so the person does not become ill. This gives long-term immunity.
Markers reward: vaccine contains dead/inactive pathogen with antigens; lymphocytes make antibodies; memory cells produced; on reinfection antibodies made faster and in larger amounts. Saying the vaccine "kills the pathogen directly" is wrong.
WJEC style4 marksExplain how the overuse of antibiotics has led to antibiotic-resistant bacteria such as MRSA, and suggest how this can be reduced.Show worked answer →
A 4-mark explain question on resistance.
By chance, some bacteria have a mutation that makes them resistant to an antibiotic. When antibiotics are overused, the non-resistant bacteria are killed but the resistant ones survive and reproduce, passing on the resistance. Over many generations the resistant strain, such as MRSA, becomes common. It can be reduced by only using antibiotics when necessary, completing the full course, and restricting their use in agriculture.
Markers reward: random mutation gives resistance; antibiotics kill non-resistant bacteria; resistant bacteria survive and reproduce (natural selection); resistant strain spreads; reduce by appropriate use and finishing courses. Antibiotics do not work on viruses.
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Sources & how we know this
- WJEC GCSE Biology specification (from 2016) — WJEC (2016)