CLASS 9th SCIENCE NOTES CHAPTER 3 HEALTH, DISEASES AND PREVENTION. This first health promotion publication is from the Government of Canada’s 1974 Blondel report, which contained a health promotion strategy “aimed at informing, influencing and assisting both individuals and organizations to accept more responsibilities and be more active in matters that affect physical and mental health.


CLASS 9th SCIENCE NOTES CHAPTER 3 HEALTH, DISEASES AND PREVENTION. “Another predecessor of the definition was the 1979 report Healthy People of the United States Surgeon General, which noted that health promotion “seeks the development of community and individual measures that can help to develop lifestyles that can maintain and enhance well-being. “




CLASS 9th SCIENCE NOTES CHAPTER 3 HEALTH, DISEASES AND PREVENTION. The “American” definition of health promotion, first promulgated by the American Journal of Health Promotion in the late 1980, focuses more on service delivery with a bio behavioral approach than on environmental support through an environment approach. Subsequently, power over the environment over behavior was incorporated. The Health Promotion Glossary 2021 reinforces the 1986 international definition.




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Q.1: Write a note on natural and organic food diet.

Ans: It means taking natural food like fruit, meat and vegetables. All these food items are a source of good health. They are free from artificial flavors and other chemicals. Natural food enables the body to grow and saves it from diseases. Consumption of unnatural food can lead to disease.

Q.2: what do you mean by fast or junk food?

Ans: Fast food or junk foods are the same. They have high calories and low nutrition but salads have low calories and high nutrition. Fast food includes gum, candy, burger, pizza, sweet desserts, fried fast food, and sugary carbonated drinks. Too much fast food may lead to obesity and many other diseases.

Q.3: What is processed food?

Ans: Food which is altered from their natural state for safety or convenience sake is called processed food. Processed food can be eaten at any time of the year. It is full of nutrition. Some processed food like milk and frozen vegetables are very good for health. Methods of processing are canning, freezing, refrigeration and dehydration.

Q.4: What are microorganisms? Name some microorganisms.

Ans: The organisms which can only be seen with a microscope are called microorganisms. They cannot be seen with a naked eye. Most of the microorganisms are harmful and cause diseases. Some microorganisms are useful for us. Virus, bacteria, fungi and parasites are some microorganisms.

Q.5: Write a short note on bacteria and bacterial diseases.

Ans: Bacteria are microorganisms that can be seen with a microscope. There are two types of bacteria; helpful bacteria and harmful bacteria. Helpful bacteria make yeast for us. Harmful bacteria spread many diseases like T.B, cholera, typhoid and tetanus etc.

Q.6: Write a short note on virus and viral diseases.

Ans: Virus is a microscopic non-cellular organism with a core of DNA or RNA surrounded by a protein coat. It requires a living host cell to replicate. It often causes diseases in the host organism. Viral diseases are polio, AIDS, small pox, measles and hepatitis.

Q.7: Write a short note on fungi and fungal diseases.

Ans: Fungi are microorganisms. They are also called decomposers. They break down the complex organic matter and convert it into simple organic materials. During this process fungi extract their nutrition from the decaying organic matter. Some fungal diseases are ringworm, athlete’s foot and histoplasmosis.

Q.8: write a short note on parasites and parasitic diseases.

Ans: Parasites are living things. They depend on other living things for food and a place to live. They cannot live by themselves. Parasites range from unicellular protozoa to multi-cellular worms. They cause various diseases like malaria, threadworm and ascariasis.

Q.8: Give a detailed note on the causes, symptoms and prevention of Malaria

Ans: Causes of Malaria:

Malaria is caused by a parasite that enters blood through the bite of an infected mosquito. It injects the parasites into the blood of a healthy person. These parasites travel to the liver, heart and lungs and from lungs into the blood stream. 

Symptoms of malaria:

Malaria goes through 3 stages:
Cold stage (shivering) Hot stage ( fever, vomiting, headaches) Sweating stage (sweating, fatigue). Severe malaria results in breathing difficulties.

Prevention of malaria:

Personal protection and environmental management play a major role in malaria prevention. Avoid mosquito bites and prevent breeding of mosquitoes. Wear long sleeves clothes, use mosquito spray in doors, take anti malaria pills and use bed nets. Do not allow standing water around you.

Q.9: What do you mean by first aid?

Ans: First aid is an immediate medical treatment with minimum equipment’s, till the patient is taken to hospital or the approach of some medical expert. In some minor cases further medical treatment is no longer needed, when the first aid is properly provided.

Providing or administrating first aid Dog Bite:

If a dog bites or scratches the body of a person, the wound may become infected with viruses of rabies, present in dog’s saliva. If the wound is bleeding, pressure bandage should be applied until bleeding stops. The damaged area should be covered with clean cotton or a piece of cloth.


If some part of the body is burnt, immediately remove clothes from the place. Run off the tape water on burnt area. In case of severe injury the patient should be taken to the nearest hospital.

Suffocation or breathlessness And Artificial respiration:

In such cases lift chest of the patient slightly upward that respiratory tract may become straight. Open the mouth of the patient and remove any blood, vomiting or secretion. Clean the mouth with a piece of cloth. This may help the patient to breathe. If not, try to help him breathe artificially. If breathing starts take the patient to the hospital at once

Snake Bite:

Take the following measures in case of snake bite.

Tie up the bitten arm or leg tightly so that poison may not move further. Wash the wound with water, lay down the patient and restrict its movements. Avoid sucking the patient’s blood from injury. It may be fatal for you. Let the wound bleed. Take the patient to the hospital at once.

Q. Identify tuberculosis as a bacterial disease.

Ans: It is a bacterial disease caused by germs. They attack the lungs, but can damage bones, brain, liver, spleen and intestine.

Causes of Tuberculosis:

A person may get the disease by inhaling ineffective respiratory droplets or by taking unpasteurized or no boiled milk.

Signs and Symptoms:

A bad cough that lasts at least three weeks or longer.

Weight loss and feeling weakness or fatigue.

Coughing up blood or mucus.

Fever and chills.


The disease can be prevented by Vaccinating infants, isolating infectious patients, improving hygienic condition and housing, Using pasteurized and properly boiled milk.


Tuberculosis can be treated by a course of antibiotics taking over several months.

Q. Discuss AIDS as a viral disease.

Ans. Causes of AIDS:

AIDS is a fatal disease. It is caused by a virus called HIV. The virus enters the body through the blood products, shared needles, razors and sexual relationship with the patient of AIDS.

Signs and symptoms:

The virus damages the white blood cells and destroys the defense system of the body. The defense system is weakened so much that even a mild infection can cause death.

Prevention and Treatment:

There is no cure for AIDS as yet.

It can be prevented by using disposable syringe, new razors and HIV tested blood.

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Q1: Cleanliness ensures health. Elaborate the statement.

Ans: Cleanliness is essential for our body and environment. Cleanliness is of many types like spiritual, mental, physical and environmental cleanliness. Spiritual or mental cleanliness is obtained through prayers. It keeps us away from evil and makes us beneficial for ourselves and others. A clean mind thinks well.

Cleanliness is part of our faith. The Holy Quran throws light on the importance of cleanliness. “ALLAH loves those who keep themselves pure and clean”.

At another place ALLAH says, “In these masjids are men who love to be clean and to purify themselves.

According to a Hades of the Holy Prophet (SAW), “Cleanliness is half of faith”.

Dirt holds germs that cause diseases. These germs ruin our health. To ensure sound physical health we need to take a regular bath, to brush teeth, to wash hands before and after meals, to wear clean dress, to keep the surrounding clean, to take regular exercise and to take enough sleep. All these things ensure sound health. They keep germs and diseases away. They regulate the functions of the body. They make the blood flow very smooth. They keep us fresh all day long.

Q.2: Briefly describe the composition of blood?

Ans: Blood is a body fluid. It consists of four main components plasma, red blood cells, white blood cells and platelets.


It is a clear extracellular fluid. It is the liquid part of the blood. It is 55% of total volume of blood. 90% of plasma is watery. Plasma is a mixture of water, fats, sugar, protein and salt. Its main job is to transport blood cells in the whole body.

Blood Cells:

Blood cells are enclosed in plasma. They are about 45% of the total volume of blood. It has red blood cells, white blood cells and platelets.

Red Blood Cells:

They are also called erythrocytes. They are red in color due to hemoglobin. They are biconcave in shape and without a nucleus. They can change their shape. They have two main functions. They carry oxygen from lungs to the body and carry carbon dioxide from tissues to lungs.

White Blood Cells:

White blood cells are called leukocytes. They protect the body from infection. Their number is less than red blood cells. They are colorless. They have a nucleus in each cell. They are 1% of the whole blood. They attack virus, bacteria and other germs.


Platelets are not actual cells. They are small fragments of cells. They are oval in shape and without a nucleus. They help in the clotting of blood.

Q.3: Anemia is a blood disorder. State its causes and effects on the body.

Ans: Anemia:

It is a disorder in red blood cells. Its causes and effects are the following.

Causes of anemia;

Loss of blood, decrease of blood, iron and vitamin deficiency, faulty red blood production and loss of hemoglobin are some of the causes of anemia.

Effects of anemia:

Due to the loss of hemoglobin, organs do not get enough oxygen. It results in pale skin, weakness, fatigue, chest pain, cold hands and feet, irregular heartbeat and headache etc.

Q.4: Eating behavior is a major cause of health disorders. List down some health issues with our eating behavior.

Ans. Body needs food to perform functions properly but wrong food choice may lead to health problems. Sometimes, it can be fatal. It increases weight, blood pressure and blood cholesterol.

Lack of calcium can increase the risk of fraction or cause unstable skeletal system

Eating rapidly can lead to overeating, heartburn and indigestion.

Fast foods cause low nutrition,

Heart diseases, diabetes, obesity and high blood pressure.

High fats raise blood cholesterol and result in heart problem. Lack of fats or oil lead to dry or cracking skin.

Low carbohydrate diet means fatigue, bone or hair loss and muscle pain.

Milk deficiency causes muscle cramps, weak nails and bone fracture.

Too much sodium can raise blood pressure.

Too much protein leads to weight gain, bad breath, constipation, diarrhea, kidney damage.

In short, taking proper amount of balanced food gives sound health.

Q.5: Differentiate between malnutrition and under nutrition.

Ans: Nutrition is the intake of food according to the body’s dietary needs. Poor nutrition leads to physical and mental disorder. Malnutrition and under nutrition means not getting a balanced diet. They are two different terms. Under nutrition is one side of malnutrition.

Malnutrition: is the deficiency, excess or imbalance of food. It is not getting proper or enough food. It is both the quality and quantity of food level. It is also the utilization or loss of nutrients. Taking too much food healthy food is also malnutrition

Under nutrition: is only the deficiency of food. It is called underfeeding. It is only the quantitative aspect of food. Starvation is one form of under nutrition.

Poverty is closely associated with under-nutrition. It can lead to fatigue, stress, less ability to work etc.

Q.6: Proper sleep and physical activities are vital for healthy growth and healthy life. Give your assessment of this statement.

Proper Sleep:

Sleep restores body’s energy, heals and repairs heart and blood vessels, repair muscle tissue and effect growth and appetite. Sleep needs both quality and quantity. If you don’t get enough or good quality sleep, you wake up feeling lazy. Sleepless person may suffer from heart/kidney disease, high blood pressure, stroke, diabetes, obesity, headaches and depression.

Physical Activities:
Proper amount of exercise benefits nearly all aspects of a person’s health. Exercise helps to control weight. It improves mental health, mood, chances of living longer, and the strength of bones and muscles. Adults, Children and adolescents need physical activity every day.

Moderate intensive activities include walking, gardening and playing tennis. 

Vigorous intensive activities include jogging, running, swimming laps, jumping rope and hiking. 

Muscle-strengthening activities include lifting weights, pushups and sit ups.

Q.9: Polio can be prevented by vaccination. Investigate why some people are hesitant to give polio vaccines to their children?

Ans: Parents hesitate or refuse to vaccinate their children due to:
Their concerns about the safety of the vaccine. They think vaccine is part of a plot to infect their children. They consider polio vaccination campaign as a western conspiracy to sterilize their children. They refuse vaccines by saying, “We don’t care about them. Why just polio? There are other diseases why are you focusing only on this one?
They mistrust the health service and concerns about vaccine delivery. They have concerns about testing drugs on children. They have concerns about there being too many vaccines.

It is due to the poor communication from the health departments and mismanagement of the provincial governments.

There are religious fatwa from well-known Ulema to refuse polio vaccines.

Q.10: Smoking is the first step to drug addiction. Enlist some of the health hazards associated with smoking.

Ans: Smoking causes cancer of the whole body. Smoking harms nearly every organ of the body. Some of the health hazards associated with smoking are the following.

Cigarettes have harmful chemicals like tar which causes cancer; nicotine increases cholesterol and carbon monoxide reduces oxygen in the body.
Smoking affects teeth and gums and can cause tooth loss.
Smoking can cause lung cancer and asthma. Smoking causes heart disease.

Smoke gives stroke. (Or)Smoke strokes you. It damages blood circulation and blood vessels and can make them thick and narrow. This makes heart beat faster and blood pressure raises. Clots can form due to smoking. Coughs, colds, wheezing, Stomach cancer or ulcers are common among smokers. Smoker’s skin does not get much oxygen. Smoking weakens the bones and causes bad breath, stained teeth, gum disease and damages sense of taste.
Smoking weakens reproduction and fertility.



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