Practise Protist diseases. 11 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Malaria is the protist disease in the specification. You need to know that it is caused by a protist, that mosquitoes are the vector, its main symptom, and how its spread is controlled by targeting mosquitoes.
Grade by grade
What you need to be able to do, from the first marks up to the top grade.
3
Name a disease caused by a protistMalaria is caused by a single-celled protist.
4
Describe the main symptom of malariaRecurrent episodes of fever (the fever keeps coming back); malaria can be fatal.
4
Identify the vector of malariaMosquitoes carry the protist and pass it to people when they bite them.
5
Describe how the spread of malaria is controlledStop mosquitoes breeding, and use mosquito nets to avoid being bitten.
6
Explain how each control method reduces spreadFewer mosquitoes, or fewer bites, means the protist is passed to fewer people.
7
Explain why controlling mosquitoes controls malariaThe protist's life cycle includes the mosquito, so it is normally passed between people only by mosquito bites.
Notes
Malaria and protists
The pathogens that cause malaria are protists (single-celled organisms).
Malaria causes recurrent episodes of fever: the fever goes away and then comes back again and again.
Malaria can be fatal.
The mosquito vector
The malarial protist has a life cycle that includes the mosquito.
A mosquito that bites an infected person takes in the protist with the blood. When it later bites another person, it passes the protist into that person's blood.
The mosquito is a vector: it carries the pathogen from one person to another.
Malaria is not spread by touching an infected person or through the air.
Controlling the spread
Prevent mosquitoes breeding: mosquitoes lay their eggs in still water, so drain or treat areas of standing water, e.g. ponds and old containers.
Kill adult mosquitoes with insecticides, e.g. sprayed inside homes.
Use mosquito nets over beds (often treated with insecticide) to avoid being bitten at night.
Each method means fewer mosquitoes or fewer bites, so the protist is passed to fewer people.
Cheatsheet
Malaria is caused by a protist
Vector = mosquito (carries the protist from person to person)
Symptom: recurrent episodes of fever; can be fatal
Example. (a) What type of pathogen causes malaria? (b) Name the animal that spreads malaria. (c) Give the main symptom of malaria.
Show the model answer
(a) A protist (1) (b) Mosquito (1) (c) Recurrent episodes of fever (1)
Explain how a control method reduces spread
2 marks6
Say what the method does to mosquitoes: fewer mosquitoes or fewer bites.
Link it to the protist: it is not passed into people's blood, so fewer people are infected.
Example. Explain how sleeping under a mosquito net reduces the spread of malaria.
Show the model answer
The net stops mosquitoes biting the person at night (1). So the protist is not passed into the person's blood, and mosquitoes cannot pick up the protist from them if they are already infected (1).
Data: effect of a control measure
3 to 4 marks7
Percentage decrease = decrease ÷ original value × 100.
Explain the result using the mosquito's life cycle or feeding.
Finish with fewer people infected by the protist.
Example. In a village, the number of cases of malaria fell from 320 per year to 72 per year after the ponds near the houses were drained. (a) Calculate the percentage decrease in the number of cases. (b) Explain why draining the ponds reduced the number of cases.
Show the model answer
(a) 320 − 72 = 248 (1); 248 ÷ 320 × 100 = 77.5% (1) (b) Mosquitoes lay their eggs / breed in still water, so there were fewer mosquitoes (1). So fewer people were bitten, and fewer protists were carried from infected people to others (1).
Shortcuts and memory tricks
Malaria = P and M: a Protist carried by a Mosquito.
Break the chain: fewer mosquitoes (stop them breeding) or fewer bites (nets) = fewer infections.
The mosquito is the vector; the protist is the pathogen. Don't swap them.
Where marks are lost
Saying malaria is caused by the mosquito, or by a virus or a bacterium. It is caused by a protist; the mosquito carries it.
Saying malaria spreads directly from person to person, e.g. by coughing or touching.
Writing 'kill the mosquitoes' without explaining why it helps: fewer mosquitoes means fewer bites, so fewer people are infected.
Writing just 'fever' when the question wants the pattern: the fever is recurrent (it keeps coming back).
Exam technique
Always name the vector and say what it does: it carries the protist from an infected person to another person.
Explanation marks come from the chain: method → fewer mosquitoes or fewer bites → fewer people infected.
In data questions, quote numbers and use percentage change where the question asks you to compare.
Quick recall
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
Malaria is spread by mosquitoes. What name is given to an animal that spreads a pathogen?
Vector
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy5 marks
Malaria is a disease that affects millions of people every year.
(a) What type of pathogen causes malaria? Tick (✓) one box.[1]
Bacterium
Fungus
Protist
Virus
(b) Malaria is spread by mosquitoes. What name is given to an animal that spreads a pathogen?[1]
(c) Give one symptom of malaria.[1]
(d) Give two ways that the spread of malaria can be controlled.[2]
Show the answer and mark scheme
(a)Answer: Protist
(b)Answer: Vector
vector
(c)Answer: Recurrent episodes of fever.
(recurrent episodes of) fever
(d)
stop mosquitoes breeding, e.g. drain standing water
sleep under mosquito nets
kill mosquitoes with insecticide
use insect repellent / cover the skin
Question 2Medium6 marks
The protist that causes malaria has a life cycle that includes the mosquito. When a mosquito bites an infected person, it takes in protists with the blood. The protists develop inside the mosquito and are passed to the next person the mosquito bites. Mosquitoes lay their eggs in still water. Most mosquitoes that spread malaria feed at night.
(a) Explain why sleeping under a mosquito net reduces the spread of malaria.[2]
(b) Explain how draining areas of still water reduces the spread of malaria.[2]
(c) Suggest two reasons why malaria is more common in hot, wet countries than in cold, dry countries.[2]
Show the answer and mark scheme
(a)
mosquitoes cannot bite the person (at night)
(so) protists are not passed to the person / mosquitoes cannot take in protists from an infected person
(b)
mosquitoes cannot lay eggs / breed
(so) there are fewer mosquitoes / vectors to carry the protists to people
(c)
more still water for mosquitoes to breed in
mosquitoes survive / breed / are active all year in warm conditions
the protists develop more quickly inside mosquitoes in warm conditions
Question 3Hard7 marks
A rapid test for malaria uses a test strip. A drop of the patient's blood is added to one end of the strip.
The strip contains monoclonal antibodies attached to a coloured dye. These antibodies can move along the strip. They bind to a protein made only by the malaria protist.
At the test line, more monoclonal antibodies against the same protein are fixed to the strip.
(a) Explain why a coloured line appears at the test line only if the patient's blood contains the malaria protist.[3]
(b) A patient has a fever. Fever is the main symptom of malaria, but it is also a symptom of many other diseases. Explain why the rapid test is useful for this patient.[2]
(c) Explain how diagnosing and treating people with malaria quickly can also reduce the spread of malaria.[2]
Show the answer and mark scheme
(a)
the protist's protein binds to the monoclonal antibodies with the dye, which move along the strip
at the test line the protein also binds to the fixed antibodies, so the dye is held there and a coloured line appears
if the protein is not present, the antibodies with the dye do not bind at the test line / move past it, so no coloured line appears
(b)
a fever alone does not show that the patient has malaria
the test shows whether the malaria protist is present, so the correct treatment can be started quickly
(c)
treated people no longer have the protist in their blood
so mosquitoes that bite them do not pick up the protist, and fewer mosquitoes can pass it on to other people