Carriers of Disease causing Micro-Organism

Question 1 Name any 2 diseases spread by housefly?

Question 2 Name 2 insects which act as carrier of disease causing micro-organism?

Question 3 Name the insect which acts as carriers of parasite of malaria?

Question 4 Name the insect which carries dengue?

Question 5 Name the diseases spread by mosquito?

Question 6 Name the microbe which causes malaria disease?

Question 7 How do houseflies carry disease causing micro-organism?

Question 8 State the ways of preventing diseases spread by houseflies?

Question 9 How do mosquitoes carry disease causing micro-organism and spread diseases?

Question 10 Mention the ways of preventing disease spread by mosquito?

Question 11 what are causative micro-organism organism?

NCERT Solutions Class 8 Science

Contents

1 Carriers of Disease causing Micro-Organism
2 Role of housefly in spreading diseases
3 Prevention of diseases spread by houseflies
4 Role of mosquitoes in spreading diseases
5 Prevention of diseases by mosquitoes

There are some insects in our environment which transfer disease causing microbes into our body and spread diseases.

The insect which transmits disease causing micro-organism to humans is called a carrier.

The two most common carriers of disease causing micro-organism are:

1)Housefly

2)Mosquito

Role of housefly in spreading diseases

The houseflies lay eggs on garbage dumps. They feed on garbage, animal excreta, dead organic matter, exposed human food. The body and legs of housefly bear a lot of fine hair. When the housefly sits on a garbage heap, human excreta or other filth and refuse, then millions of disease causing micro-organism present in them stick to the hairy legs and other body parts of the houseful. And when this housefly now sits on our uncovered food, then micro-organism sticking to the hair on its legs and other body parts are transferred to food. In this way our food get contaminated with disease causing micro-organism. When this contaminated food is consumed by a person, then the disease causing micro-organism enter into his body and cause various diseases.

For Example : Cholera, Tuberculosis, Typhoid, Diarrhoea.

Prevention of diseases spread by houseflies

1)We should not leave household garbage here and there.

2)The food should always be kept covered so that flies cannot sit on it.

3)We should avoid eating uncovered food items from road-side stalls.

4)The flies should be killed by using insecticides spray.

5)Some of the diseases spread by houseflies can be prevented by vaccination.

Role of mosquitoes in spreading diseases

Mosquito acts a carrier of disease causing micro-organism and spreads diseases from one person to another. They carries microbes inside its body. Mosquitoes breed in stagnant water of ponds, dirty drains, pools, ditches and shallow lakes etc.

The most common disease spread by mosquitoes is malaria. The female anopheles mosquito which carries the parasite of malaria. The malarial parasite called Plasmodium causes malaria disease.

1)When a female anopheles mosquito bites a person suffering from malaria disease, it sucks the blood of that person which contains the malarial parasite microbes.

2)When this infected female anopheles mosquito bites a healthy person to suck his blood, it transfers the malarial microbes into his blood stream along with saliva.

3)By receiving malarial parasite microbes in blood, the healthy person also gets malarial disease.

Another disease spread by mosquitoes is dengue. It is caused by virus. The female aedes acts a carrier of dengue virus and spread the dengue from person to person.

Prevention of diseases by mosquitoes

1)The pools of stagnant water around the houses should be drained out so that mosquitoes may not breed in them.

2)We should not let water collect in coolers, tyres, flower pots.

3)The window and doors of the house should have fine iron wire mesh so that mosquitoes cannot enter the house.

4)Oil should be sprayed on the surface of water in dirty water drains to kill the larvae of mosquitoes.

5)Mosquito repellant creams should be applied on the exposed parts of the body.

The micro-organism which cause a disease is known as causative micro-organism of that disease.

Other Notes from Chapter 2 Micro Organisms Friend and Foe