Year 9 Science · Unit 1 · Lesson 2

Types of Pathogens

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Learning Goals

Warm Up

Because… chain

Fill in the missing effects. Each cause leads to the next step in viral infection and spread.

A virus particle contacts a host cell and attaches to a receptor on the cell surface
→
The virus injects its genetic material (DNA or RNA) into the host cell
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The host cell's own machinery (ribosomes, enzymes) reads the viral genetic instructions
→
Hundreds of new virus particles are assembled inside the cell until it bursts (lyses)
→

Overall outcome:

Your Turn

Real-world context

In 2023, a 14-year-old student in Sydney presented to her GP with a high fever, sore throat, and difficulty swallowing. The GP took a throat swab and sent it to pathology. The laboratory result came back positive for Streptococcus pyogenesa bacterium. The GP prescribed a 10-day course of amoxicillin (an antibiotic). Two weeks later, the student's younger brother presented with identical symptoms, but his swab tested negative for bacteria; no pathogen was isolated. His GP explained that his sore throat was likely caused by a virus and recommended rest, fluids, and paracetamol only.

(a) Why could the GP prescribe amoxicillin for the first patient's infection? Refer to the structure of bacteria and how antibiotics work in your answer.

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(b) Why would amoxicillin be ineffective if the second patient's sore throat is caused by a virus? Use your knowledge of virus structure and replication to explain.

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Show What You Know

1. A patient with a cold (viral infection) demands antibiotics from their doctor. Explain two reasons why prescribing antibiotics in this situation is harmful, one reason relating to the patient, and one relating to the broader community.

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2. Malaria is caused by Plasmodium, a protozoan parasite. A student says: "Malaria is caused by mosquitoes." Identify the error in this statement and correct it using precise scientific language.

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Wrap Up

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

HSCScience · Year 9 Science · Unit 1 · Lesson 2 · Apply Worksheet