Year 9 Science · Unit 1 · Lesson 11

Antibiotics and Antivirals

Challenge Worksheet

Name

Date

Class

Learning Goals

Identify subtle scientific errors in a student's explanation of antibiotic resistance.
Distinguish between individual immunity becoming resistant and bacterial populations evolving resistance.
Construct a scientifically accurate account of how resistance develops through natural selection.

Go Deeper

Find the mistake

A student wrote this answer

"Antibiotic resistance is caused by patients' immune systems becoming resistant to antibiotics over time. When a person takes too many antibiotics, their body gets used to them and the antibiotics stop working. The bacteria inside the patient then copy this resistance from the immune system, which is why you shouldn't take antibiotics unnecessarily. If everyone just stopped taking antibiotics for a few years, the bacteria would lose their resistance and antibiotics would work again."

1. Identify at least two distinct scientific mistakes in the student's answer. Be specific about which sentences contain errors.

Challenge 2 marks

2. Rewrite the student's answer correctly. Your version must: (a) correctly explain what develops resistance (the bacteria, not the patient), (b) describe the role of natural selection and random mutation, and (c) explain why resistance does not simply "disappear" if antibiotics stop being used.

Challenge 4 marks

3. Explain why this kind of mistake is very easy to make. What real biological concept does the student seem to be confusing antibiotic resistance with?

Challenge 2 marks

Go Deeper, continued

4. The Australian Veterinary Association has pushed to ban antibiotic use in livestock for growth promotion. Explain why antibiotics given to farm animals can contribute to antibiotic resistance in human patients, even if those patients have never taken antibiotics themselves. Describe the pathway by which resistant bacteria could travel from a farm to a hospital ward.

Challenge 4 marks

Show What You Know

1. Antivirals like oseltamivir (Tamiflu) reduce symptom duration by about 1–2 days for influenza. A critic argues this modest benefit does not justify the cost of antiviral drugs. Construct a scientific counter-argument for why developing and using antivirals is still important, even when they do not eliminate the virus.

Challenge 3 marks

2. Why are new antibiotics so difficult and expensive to develop, and what does this mean for the future of treating bacterial infections if resistance continues to rise?

Challenge 3 marks

Wrap Up

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