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Class 9 Why Do We Fall Ill

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Class IX


A regular supply of food or a balanced diet is essential for human beings in order to keep fit and to carry on all the life processes. A proper food is required for proper functioning of cells, their tissues and organs. Anything that disturbs the proper functioning of cells, tissues and organs will result in the lack of proper activity of the body or unhealthy body. Thus, health is considered to be the state of perfect functioning of body and mind, not interfered by diseases. So what do you understand by the term “a healthy individual”? An individual free of disease is termed, healthy individual.

But do you know health has a different meaning in different contexts? For example, for old people, ability to go out for a walk is good health. If there are unable to do so, it is considered their health is not good. Similarly, a youngster is healthy, if he can run, jump and play. Therefore, a good health is a healthy body with a healthy mind and healthy attitude.

Health does not simply means “absence of disease” or “physical fitness”. It could be defined as state of complete physical, social and mental well-being.

The significance of Good Heath:

  • It increases our efficiency for doing work, which in turn increases the productivity and brings economic prosperity.
  • It makes an individual happy and cheerful.
  • A healthy person can give proper attention to others in the family.
  • It gives a condition for our purposeful existence in this world.
  • It also increases the longevity of people and reduces infant and maternal mortality.


The term disease means Dis-ease i.e. without ease or comfort. You all must, at one time or another in your life, must have felt uncomfortable, must have suffered from fever, body-aches, cold, cough, or vomiting. Such conditions where you feel uncomfortable or uneasiness is known as disease. It is just the opposite of health.

A disease can be defined as any condition that may lead to discomfort, distress, health problems, or death of the affected person. It may be due to defective heredity, inappropriate diet, disturbed metabolism or pathogenic attack.

A person is said to be disease free if there is no discomfort or derangement of the functioning of the body.

Important notes: A disease-free individual without suffering from any particular disease can be in good health or in poor health.

Difference between a healthy and a disease-free state of human body

Good health is the ability of an individual to realize his or her full potential. For example, if an athlete is tired after running about 100 m, then he cannot be called a diseased person. However, he is not healthy either. Therefore, it can be concluded that one can have poor health without having any identifiable disease.

Important notes: The state of not having any disease is not the same as being healthy.


Healthy state Disease-free state
It is the state of complete physical, mental and social well being. It is the state of absence of discomfort or derangement.
It depends on both the individual as well as physical and social environment. It is related to the individuals only.
A healthy individual is disease free as well. A disease-free individual can be healthy or unhealthy
  1. State any two conditions essential for good health. (NCERT)

Ans. The two conditions essential for good health are:

  • Better health facilities and more professionals to deal with health problems.
  • Basic necessary conditions to prevent diseases. For example, proper garbage collection and disposal, clearing of drains, the supply of healthy drinking water, etc.
  1. State any two conditions essential for being free of disease. (NCERT)

Ans.The two conditions essential for being free of diseases are:

  • Personal hygiene and cleanliness to stay away from diseases.
  • Intake of balanced diet
  1. Are the answers to the above questions necessarily the same or different? Why?(NCERT)

No. The answers to the above questions may not necessarily be the same. This is because a disease-free state is not the same as being healthy. Good health is the ability of an individual to realize his or her full potential. Individuals can have poor health without having any identifiable disease. Also, health is related to society and community, whereas having a disease is about an individual sick person.

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Chapter 1: Matter in Our Surroundings
Chapter 2: Is Matter Around us Pure
Chapter 3: [Atoms and Molecules].
Chapter 4: Structure Of Atom
Extra Questions-Answers Chapter: 4

Chapter 5: Cell – Basic Unit of Life

Chapter 6: Tissues, Organs, Organ System, Organism

Chapter 7:  Diversity in Living Organisms

Chapter 8: Motion

Chapter 9: Force and Newton’s Laws

Chapter 10: Gravitation

Chapter 11: Work, energy, and power

Chapter 12: Sound

Chapter 13: Why do we fall ill?

Chapter 14: Natural Resources

Chapter 15: Improvement in Food Resources