Edexcel IGCSE Biology · Spec 1.4
Pathogens and Viruses
What a pathogen is, the four types (bacteria, fungi, protoctists and viruses), the structure of a virus, and why viruses are not truly living.
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Pathogens and Viruses
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Spec 1.4
What you need to know
- Define a pathogen and list the four types
- Describe the range and structure of viruses
- Explain how viruses reproduce inside living host cells
Active recall
Quick check
Answer each question before opening the answer.
What are the four types of pathogen?
Bacteria, viruses, fungi and protoctists.
Why are viruses not considered living organisms?
They have no cellular structure and cannot carry out life processes or reproduce on their own — they can only replicate inside a host cell.
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