Chapter 13 Why Do We Fall ill

Health is the condition of the body when the body is fit in all aspects like physical, mental, social etc. This healthy condition can be interrupted by many pathogen and leads to disease which may communicable, non communicable, congenital. Here we will learn and understand what are causative organism how we can prevent from disease. Our immunity plays very important role let’s try to understand.

Download pdf of NCERT Solutions for Class Science Chapter 13 Why Do We Fall ill

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Exercise 1

  • Q1 State any two conditions essential for good health.

    The two conditions essential for good health are :

    (i) Person should be physically fit and fine.

    (ii) He should have a good and clean environment.

    Q2 State any two conditions essential for being free of disease.

    The two conditions essential for being free of diseases are :

    (i) Maintaining personal and domestic hygiene.

    (ii) Taking a good food (balanced diet)  that contains carbohydrates, fats, proteins, vitamins, fibres, and proper quantity of water.

    Q3 Are the answers to the above questions necessarily the same or different? Why?

    No. The answers are not the same all the time. This is because the meaning of health varies from person to person. For example, good health for a dancer may be being able to stretch his body into difficult but graceful positions. Good health is the ability of an individual to realise 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. Hence, the conditions for good health and for being disease free can be the same or even different.

Exercise 2

Exercise 3

  • Q1 Why are we normally advised to take bland and nourishing food when we are sick?

    During sickness the body becomes weak and the digestive system does not work properly. Immunity of the body decreases during disease of infection. So we are normally advised to consume bland and nourishing food when we are sick so that we can get the nutrients and energy quickly to fight off the foreign disease-causing agents.

    Q2 What are the different means by which infectious diseases are spread?

    Infectious diseases can be spread in several ways such as air, water, sexual contact, blood, and vectors.

    (i) Through Air: Sneezing or coughing little droplets thrown in the air carry microbes which can cause the spread. For example, tuberculosis, pneumonia, etc. spread through air.

    (ii) Sometimes causal micro-organisms get mixed with drinking water and spread water borne diseases. Cholera for example is water borne disease.

    (iii) Sexual Contact: Diseases such as syphilis or AIDS are transmitted by sexual contact.

    (iv) Certain diseases such as AIDS can spread via blood to blood contact during blood transfusion or pregnancy.

    (v) Through vectors : These are intermediaries which carry the infectious agents from the patient to the host. For example mosquitoes spread malaria.

    Q3 What precautions can you take in your school to reduce the incidence of infectious diseases?

    Precautions to reduce incidence of infectious diseases are:

    (i) Drinking clean and hygienic water.

    (ii) Keeping the toilet neat and clean.

    (iii) Stay away from the diseased person.

    (iv) Using handkerchief to cover the mouth while sneezing or coughing.

    (v) Initiations of the school immunization program for children.

    (vi) Preventing over crowded classes.

    Q4 What is immunisation?

    Immunization is the process whereby a person is made immune or resistant to an infectious disease, typically by the administration of a vaccine. Vaccines stimulate the body’s own immune system to protect the person against subsequent infection or disease.

    Q5 What are the immunisation programmes available at the nearest health centre in your locality? Which of these diseases are the major health problems in your area?

    The immunization programme is available at the nearest health centre in our locality.

    (i) For infants : DPT, polio, measles and MMR.

    (ii) For children : Typhoid, TT, DT, smallpox and TAB.

    (iii) For pregnant women : TT and hepatitis-B.

    The diseases like jaundice and typhoid are major health problems in our locality.

Exercise 4

Popular Questions of Class 9 Science