Pathogens — Fungi and Protists

This lesson covers fungal and protist pathogens as required by the Edexcel GCSE Combined Science specification (1SC0). You need to understand how fungi and protists cause disease and describe the specific examples of rose black spot and malaria.

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Fungal Pathogens

What Are Fungi?

Fungi are eukaryotic organisms. They can be:

• Single-celled — e.g. yeast
• Multicellular — e.g. mushrooms, moulds

Multicellular fungi are made of thread-like structures called hyphae (singular: hypha). A network of hyphae is called a mycelium. Fungi reproduce using spores, which can be spread by wind, water or animals.

Not all fungi are pathogenic — many are decomposers that play a vital role in nutrient cycling. However, some fungi cause diseases in plants and animals.

How Fungi Cause Disease

Pathogenic fungi can cause disease by:

1. Invading tissues — fungal hyphae grow into plant or animal tissues, digesting and destroying cells.
2. Producing spores — spores can spread through the air or water to infect new hosts.
3. Some produce toxins — although this is less common than in bacteria.

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Example: Rose Black Spot