Malaria is a transmissible disease that is common in some tropical regions. It is caused by a pathogen that is passed from person to person by a vector. Tab...
Question 1 Report
Malaria is a transmissible disease that is common in some tropical regions. It is caused by a pathogen that is passed from person to person by a vector. Table 1.6 shows the number of malaria cases in a region before and after different control methods were introduced.
| Control method used | Malaria cases per 1000 people |
|---|---|
| none | 85 |
| mosquito nets over beds | 40 |
| nets plus draining still water | 18 |
| nets, draining water plus insecticide | 6 |
(a) State the name of the pathogen that causes malaria. [1]
(b) Name the vector that transmits malaria. [1]
(c) Describe how the pathogen is transmitted from an infected person to a healthy person. [3]
(d) Using Table 1.6, explain how the use of mosquito nets over beds reduces the number of malaria cases. [3]
(e) Explain why draining areas of still water helps to control malaria. [3]
(f) State two other methods that could be used to control the spread of malaria. [2]
Answer Details
This question is about malaria: a pathogen carried by a vector, and how control methods break the transmission cycle. The table shows cases falling as more controls are combined.
(a) The pathogen that causes malaria is Plasmodium (a protoctist/protozoan) [1].
(b) The vector that transmits it is the (female Anopheles) mosquito [1].
(c) Transmission in three steps: a mosquito bites an infected person and takes up the pathogen in their blood [1]; the pathogen develops inside the mosquito [1]; then the mosquito bites a healthy person and passes the pathogen into their blood [1].
(d) Using the data, nets reduce cases from 85 to 40 per 1000 [1]; the net acts as a barrier that stops mosquitoes biting people while they sleep at night [1]; so fewer people are infected and transmission is reduced [1].
(e) Draining still water helps because mosquitoes lay their eggs and their larvae develop in still water [1]; removing the water removes these breeding sites [1]; so there are fewer mosquitoes (vectors) and less transmission [1].
(f) Any two other control methods (1 each): use insecticides; take antimalarial drugs / prophylactics; use insect repellents; or fit screens on windows [2].
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