NCERT Solutions for Class 5 EVS Chapter 8

When a mosquito bites, it stabs the skin by using a special part of their mouth which sucks up blood. As the mosquito is feeding on humans, it injects saliva into the skin. The human body reacts to the saliva and this makes a bump and itching starts.

The diseases caused by mosquitoes are- malaria, chikungunya virus, dengue.

The measures that should be taken to prevent ourselves from mosquitoes are-
• Wearing a long as well as light-coloured clothing when we go outdoors, especially when mosquitoes are active.
• Using mosquito repellents, coils etc.
• Following the instructions of using mosquito repellent.
• Fitting proper mosquito nets on the doors and windows or beds of your house, on your tent and camping shelter

Reema is suffering from Malaria
Malaria is spread by Anopheles mosquitoes. This disease is common in rainy or monsoon season as there is a problem of water blockage or collection in many areas which makes it a breeding ground for mosquitoes at domestic and public surroundings. Mosquitoes breed in stagnant water.

Malaria is a life-threatening disease which is transmitted by the bite of an infected Anopheles mosquito. The infected mosquitoes carry the Plasmodium parasite and when this mosquito bites you, the parasite is released into our bloodstream.

The symptoms of a malarial patient are as follows-
• high fever
• shivering and chills.
• headaches.
• vomiting.
• muscle pains.
• diarrhoea.
• Nausea
• Convulsions(shaking)
• Sweating

Disease is a condition when our body is unable to not function normally. A person who is suffering from a disease becomes sick and weak.
Disease can occur due to many different reasons. Diseases can be classified into two types – communicable disease and noncommunicable disease.

Mosquitoes use different methods to find humans. They are attracted to the carbon dioxide which is emitted by the humans and other animals. They also use their receptors and vision to find other signals like the body heat, perspiration and skin odour to find their host.

We should not allow water to stagnate at one place near our house or in our neighbourhood because mosquitoes breed in stagnant water and these mosquitoes are the carriers of many diseases like malaria and dengue.

A microscope is an instrument which is used to observe small objects, even cells. The image of the object gets magnified with the help of at least one lens in the microscope. This lens bends light toward the eye and makes the object appear larger than what it actually is.

From early times, the dried and powdered bark of the Cinchona tree was used to make a medicine for malaria. Earlier people used to boil the bark powder and strain the water which was given to the patients suffering from malaria. Now a tablet called chloroquine is made from it and given to the patients.

Mosquitoes breed by laying eggs in stagnant water. We can keep them off by either covering or clearing out any stagnant water that is in our home. Buckets, coolers, and other containers must be regularly cleaned and checked for stagnant water.

Fish are put in water tanks or ponds because the fish eats larvae of mosquitoes that develop in water and thus stops breeding of mosquitoes.

A deficiency disease is a disease which is caused due to the lack of essential nutrients in the diet such as vitamins and minerals in the human body. For example- Vitamin B1 deficiency causes beriberi, lack of iron in the body can lead to anaemia.

A blood test is a test in which a sample of blood is taken from the body to be tested in a lab. Blood tests are done to check the levels of glucose, haemoglobin, or white blood cells. It helps to notice problems like a disease or a medical condition.

Haemoglobin is a protein in red blood cells which contains iron in it and is used to transport oxygen around the human body. Haemoglobin is found in the red blood cells of all vertebrates apart from white-blooded fish.

Flies can spread diseases because they feed freely both on human food and filthy matter. The fly picks up disease-causing organisms while crawling and feeding. They often sit on dead animals, rotten food, manure, garbage and trash. Because they frequent those places, they pick up and spread diseases that are harmful to human by sitting on the food we eat or surfaces by defecating on them.

Anaemia is deficiency of blood in a person. It happens when a person doesn’t have the normal amount of red blood cells or if the person is low on haemoglobin, a protein in red blood cells.

It is important to take iron rich foods like green leafy vegetables, liver, tofu, spinach, eggs, whole grains, pulses and beans, meat, fish, dry fruits, jaggery and amla.

Anaemia is affecting both their physical as well as mental health of the children. Due to anaemia, children do not grow well, and their energy levels are low. This also affects their ability to study properly. Now health check -ups are being done in the schools and health cards are being made for all the children. Anaemic children are also being given iron tablets.

Algae are aquatic, plant-like organisms. Algae can be found in oceans, lakes, rivers, ponds and even in snow, anywhere on earth. They are a type of plant-like living things that can make food from sunlight by photosynthesis. The algae spread a lot during the rainy season. Thus, algae are very small green plants that are found around the watery spots.

The normal range of haemoglobin in men is – 13.5 to 17.5 grams
The normal range of haemoglobin in women is- 12.0 to 15.5 grams

The diseases caused by flies are Typhoid fever. Dysentery. Cholera.

It is advised not to eat cut and uncovered food as such food is easily attacked by microorganisms, flies or insects which spread germs and act on them. They contaminate the food and if we eat that food, it can spread diseases and can lead to diseases like typhoid, dysentery etc. So, it is good to avoid them and eat healthy and hygienic food.

A blood test report helps the doctors to know about the organs of a person, evaluate how well are the organs like the kidneys, liver, thyroid, and hear and are they working properly or not. It also helps to diagnose the disease a person is suffering from and know conditions such as cancer, HIV/AIDS, diabetes, anaemia and coronary heart disease. It helps the doctors to give treatment accordingly.

Mosquitoes know that water can evaporate at a fast rate, so they regularly look for deep pools of water for laying their eggs. Mosquitoes usually lay eggs in shallow water which evaporates before their eggs hatch. Deep puddles and stagnant swamps are a mosquito’s favourite place to breed.

Microscope helps the doctors in examining the samples. They can exactly diagnose the type of microorganisms living in our body or the level of the different kinds of cells in the body.

A health check -up helps us to find early signs of any health issues. When we go for a health check, the doctor checks our medical history, our family’s history of disease and our lifestyle, including your diet, weight, physical activity etc.

A regular health check-up is important as it helps us to know are possible health condition at an early stage as prevention is always better than cure. Early finding of the disease or heath disorder always gives a better chance to fight against the disease without any kind of complication.

We should keep the water pots, coolers and tanks clean and dried because the mosquitoes breed in water logged and damp places especially in the rainy season. Therefore, we should ensure that we keep our coolers, pots clean by changing their water regularly.

In those days, thousands of people were dying due to a disease, now called malaria. The disease was found in areas where there was a lot of rain, or in swampy places. People thought that the illness was caused by some poisonous gas that came from the dirty swampy areas. They gave it the name ‘malaria’ which means ‘bad air’. A doctor had seen tiny germs in the blood of one of the patients, when he observed it under a microscope. But he could not understand how these had got into the patient’s blood. Ross used to carry empty bottles and chase mosquito after mosquito and put the mosquitoes into a mosquito net in which had a patient of malaria. The mosquitoes would have a feast, biting these patients. The patients were paid one anna for allowing one mosquito to bite them. He used to cut open the mosquito’s stomach and peep into it and spend hours and hours over the microscope.
Once he himself also fell ill with malaria and had to spend months like this with the microscope. One day he caught a few mosquitoes that looked different. They were brownish with spotted wings. He looked into the stomach of one of the female mosquitoes and saw something black there. He saw that these were tiny germs that looked just like the ones that were found in the blood of malaria patients. This proved that mosquitoes did spread malaria.

In December 1902, Ronald Ross was awarded the highest award for his discovery—the Nobel Prize for medicine he found for malaria.

The malaria parasite enters the blood stream of a person and travels to the liver. When the parasite becomes mature, it leaves the liver and starts infecting red blood cells. Malaria is caused by a single-celled parasite of the species plasmodium. The parasite is transmitted to humans most commonly through mosquito bites.