Okay, I realised that my educational system really focuses a lot on mosquitoes.

Here’s another question from the 2020 Primary School Leaving Examination:

a) Oil is sprayed on stagnant water as shown. Explain how this prevents mosquito from breeding. [1]

(b) Malaria is a disease spread by mosquito A. Children infected with malaria are found to be bitten more often by mosquito A. Joel wanted to find out if children infected with malaria are more attractive to mosquito A due to a certain smell that they produce. He used the set-up shown with 20 of mosquito A in box P.  

Joel counted the number of times mosquitoes landed on the shirt for 3 minutes. He repeated the experiment using another shirt worn by an uninfected child in box Q.

(i) State a hypothesis on how the smell on a shirt affects its attractiveness to mosquito A. [1]

(ii) Joel used a white shirt instead of a black shirt for the experiment. Suggest why using a white shirt allows him to obtain more accurate results. [1]

(iii) Joel recorded his results in the table.   Scientists are able to store the smell produced by infected people in a container. Suggest how Joel could use this smell and his results to reduce the number of bites on people. [1]

Question reproduced from Joyous Learning  

solution  

a) Oil forms a barrier and prevents air from entering the water. The larvae hence lack the air to stay alive.

b) i) A shirt that has the smell produced by children infected with malaria is more attractive to mosquito A than a shirt that does not have that smell.

ii) A white shirt contrasts with the black mosquitoes more clearly, thus making the mosquitoes more visible. So, people can count the mosquitoes accurately. A black shirt, on the other hand, makes mosquitoes harder to spot.

iii) Mosquito A are attracted to the smell produced by infected people. This smell could be released in an unoccupied part of a house to lure the mosquitoes away from where people actually are. Alternatively, the container which stores the smell produced by infected people can be used to attract and trap mosquitos, which will then lead to fewer bites on people.