Year 9 Science · Unit 1 · Lesson 11

Antibiotics and Antivirals

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Learning Goals

Warm Up

Because… chain

Fill in the missing effects in the chain below. Each cause leads to the next step, follow the logic from antibiotic misuse to a resistant strain developing.

A patient takes antibiotics but stops after 3 days because they feel better.
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Some bacteria in the patient's body carry random mutations that give slight resistance.
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These slightly resistant bacteria survive and reproduce rapidly.
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Resistant bacteria can pass resistance genes to other bacteria through plasmid conjugation.
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The same antibiotic is now much less effective when the patient gets sick again.
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Overall outcome, what does this process lead to in the wider community?

Your Turn

Real-world context

In 2023, a Sydney GP (general practitioner) saw a patient with confirmed influenza, flu had been identified by a rapid antigen test. The patient was exhausted and asked the doctor to prescribe antibiotics to "help clear it up faster." The GP declined to prescribe antibiotics but did give advice on managing the illness. This is standard clinical practice in Australia, supported by the Australian Commission on Safety and Quality in Health Care.

(a) Explain, using biological reasoning, why prescribing antibiotics for a confirmed influenza infection would be scientifically incorrect. Your answer must refer to the structure of viruses and how antibiotics work.

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(b) The GP mentioned that prescribing unnecessary antibiotics causes a wider public health problem. Explain what this problem is, and describe two pieces of advice the GP might have given the patient instead of antibiotics.

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Show What You Know

1. MRSA (methicillin-resistant Staphylococcus aureus) is a bacterium that no longer responds to common antibiotics. Using the concept of natural selection, explain in 3–4 steps how MRSA arose from ordinary Staphylococcus aureus bacteria.

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2. The WHO estimates antibiotic resistance could cause 10 million deaths per year by 2050. Suggest two actions, one by individuals and one by governments, that could reduce this risk.

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Wrap Up

In one sentence, what was the main idea of this lesson?

HSCScience · Year 9 Science · Unit 1 · Lesson 11 · Apply Worksheet