Fungal and protist diseases (AQA GCSE Biology Combined Science): Revision Notes
Fungal and protist diseases
What are fungi and protists?
Both fungi and protists are types of organisms that have nuclei in their cells. Some of these organisms can cause diseases in humans, animals, and plants.
Fungi
Fungi are living things that can be made up of just one cell or many cells. The single-celled types include yeasts and moulds.
Key features of fungi:
- They have cell walls around their cells
- They do not have chloroplasts (so they cannot make their own food like plants do)
- Some fungi make poisonous substances called toxins that can make people ill
Examples: Yeasts are used to make bread rise and to brew alcoholic drinks.
Protists
Protists are always single-celled organisms. They do not join together to make tissues like other organisms do.
Key features of protists:
- They exist in many different varieties
- Some protist species live as parasites
- Parasitic protists benefit by living inside other organisms, but they harm their host
Malaria - a serious protist disease
Malaria is one of the most dangerous diseases caused by protists. It affects millions of people worldwide.
Symptoms of malaria:
- Episodes of high fever that keep coming back
- Can cause death if not treated properly
How malaria spreads: The protists that cause malaria are parasites. They have a complex life cycle that involves mosquitoes. Here's how it works:
Worked Example: Malaria Transmission Cycle
Step 1: A mosquito bites an infected person and picks up the malaria protists
Step 2: The protists develop inside the mosquito
Step 3: When the mosquito bites another person, it passes on the protists
Step 4: The protists multiply in the person's liver and red blood cells
The mosquito acts as a vector - this means it carries the disease-causing organism from one person to another.
Controlling malaria:
- Use mosquito nets over beds at night
- Prevent mosquitoes from breeding by removing areas of still water
Fungal diseases
Rose black spot
This is a common plant disease caused by fungi.
Example: Rose Black Spot Disease Process
What happens:
- Purple or black spots appear on plant leaves
- The spots often turn yellow and the leaves fall off
- This reduces the plant's ability to make food through photosynthesis
- The plant cannot grow properly
How it spreads:
- Fungal spores travel through the air
- Spores can also spread in water during rain
Treatment:
- Spray fungicides (chemicals that kill fungi) onto the plants
- Remove and destroy infected leaves
Ringworm
This is a fungal disease that affects humans.
How it spreads:
- Direct contact with infected skin
- Contact with contaminated clothes or objects
Prevention:
- Keep good personal hygiene
- Avoid sharing personal items like towels or clothes
Key Points to Remember:
- Fungi and protists are organisms with nuclei that can cause diseases
- Malaria is caused by protist parasites and spread by mosquito vectors
- Prevention is key - use mosquito nets and remove breeding sites to control malaria
- Fungal diseases like rose black spot can be treated with fungicides
- Good hygiene helps prevent fungal infections like ringworm