Protist diseases — AQA GCSE Combined Science
Test yourself on Protist diseases with AQA GCSE practice questions.
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Protist diseases explained
Malaria is caused by protist pathogens, not by a virus or bacterium.
Read the full explanation
The protists are transmitted to humans by the bite of an infected mosquito, which acts as a vector. The mosquito takes blood containing the protists from an infected person and later injects them into another person when it feeds again. Inside the human body the protists reproduce and damage red blood cells, causing symptoms such as fever and fatigue. Because the pathogen is a protist, antibiotics that target bacteria are not effective against it. Control measures therefore target the vector, for example using mosquito nets and insecticides, rather than relying on antibacterial drugs.
The malarial protist has a life cycle that includes the mosquito. Malaria causes recurrent episodes of fever and can be fatal. The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten.
Malaria is caused by a protist, a single-celled eukaryotic pathogen. The protist's life cycle requires two hosts: a mosquito, which acts as a vector, and a human. When an infected mosquito bites a person, protists enter the blood and reproduce, eventually destroying red blood cells. This causes recurrent episodes of fever as cells burst in synchrony, and in severe cases the disease can be fatal. Because the mosquito is essential for transmission, control focuses on the vector. Preventing mosquitoes from breeding means removing or covering standing water where larvae develop. Using mosquito nets, especially insecticide-treated nets, creates a physical barrier that stops mosquitoes biting people while they sleep. These measures interrupt the life cycle and reduce the spread of malaria.
Your focus
- State that the pathogens causing malaria are protists.
- Describe how mosquitoes act as vectors to transmit malaria protists between people.
- Explain why control measures target mosquitoes rather than using antibiotics against the protist.
Show all 6 objectives
- State that malaria is caused by a protist and transmitted by mosquitoes.
- Describe how the malarial protist life cycle involves both mosquitoes and humans.
- Explain how preventing mosquito breeding and using mosquito nets reduce the spread of malaria.
Protist diseases exam tips
Marking Points
- Malaria is caused by protist pathogens, so the pathogen group is protists.
- The protists are transmitted to humans by mosquitoes, which act as vectors.
- A vector is an organism that carries a pathogen from one host to another without being infected itself in the same way.
- The mosquito bites an infected person, takes up protists with blood, then injects them into another person when it feeds.
- The protists reproduce in the human body and damage red blood cells, producing symptoms such as fever.
- Control targets the mosquito vector, for example mosquito nets and insecticides, because the pathogen is a protist.
- Malaria is caused by a protist, not by a bacterium or virus.
- The mosquito is a vector that carries the malarial protist between human hosts.
- The protist life cycle includes both the mosquito and a human host.
- Infection leads to recurrent episodes of fever and can be fatal.
- Control methods include preventing mosquitoes from breeding, for example by removing standing water.
- Mosquito nets reduce transmission by preventing bites from infected mosquitoes.
Examiner Tips
- 💡Use the word protist when naming the pathogen, and keep the mosquito described as the vector.
- 💡Explain transmission as a sequence: infected person, mosquito bite, protists transferred, new person infected.
- 💡If asked about prevention, link each method to interrupting the vector, such as nets or insecticides.
- 💡Name the pathogen group clearly: malaria is caused by a protist.
- 💡Use the term vector when describing the mosquito's role.
- 💡Link each control method to how it breaks the life cycle, such as nets preventing bites or removing water preventing breeding.
Common Mistakes
- Saying malaria is caused by a virus or bacterium: correct this by stating that the pathogen is a protist.
- Calling the mosquito the pathogen: correct this by describing the mosquito as the vector that transmits the protist.
- Suggesting antibiotics cure malaria: correct this by explaining that antibiotics act on bacteria, not protists.
- Thinking malaria is caused by a virus or bacterium; the correct cause is a protist.
- Believing the mosquito itself is the pathogen; the mosquito is the vector that transmits the protist.
- Assuming malaria is spread directly from person to person; transmission requires the mosquito vector.