Extra Questions for Class 9th: Ch 13 Why do we Fall ill (Science) Important Questions Answer Included

Very Short Answer Questions (VSAQs): 1 Mark

Q1. What is community health?
An aspect of health, which deals with the well-being (physical, mental and social) of people of a community is called community health.

Q2. How is a disease identified?
A doctor identifies a disease by its symptoms and signs.

Q3. Name the causative organism of cholera.
Vibrio cholerae.

Q4. Which disease is caused by Helicobacter pylori?
Peptic ulcers.

Q5. What is the primary cause of haemophilia?
Primary cause of haemophilia is change in chromosome sequence.

Short Answer Questions-I (SAQs-I) : 2 Marks

Q1. (i) What are communicable diseases? Write its one example.
(ii) How do these spread?


Diseases that can be spread from one person to another are called communicable diseases, e.g., cough and cold, Pneumonia.
They can spread through air, sneezing water or air contact.

Q2. Write two examples each of
(i) Viral diseases
(ii) Bacterial diseases


(i) AIDS, dengue fever
(ii) Tuberculosis, typhoid, cholera

Q3. Which of the following diseases will cause major ill-effects on general health - Elephantiasis, Cough and cold, Tuberculosis, Diarrhoea. What are such diseases called?


Elephantiasis and tuberculosis. Such diseases are called chronic diseases.

Q4. Name the causal organism of AIDS. Why a person suffering from AIDS cannot fight even very minor infections?


Causal organism: HIV 1. 
A person suffering from AIDS cannot fight even very minor infections because it damages the immune system of the person and damages its function.

Q5. State any four ways by which AIDS virus spreads from an infected person to a healthy person


Four ways by which AIDS virus spreads are:
(i) Sexual contact with infected person.
(ii) Pregnant mother to her foetus.
(iii) Blood contact with infected person.
(iv) Using needle or syringe of infected person.

Short Answer Questions-II (SAQs-II) : 3 Marks

Q1. (i) Write difference between acute and chronic diseases.
(ii) Pick out chronic diseases from the list given below: Japanese encephalitis, viral fever, common cold, tuberculosis.


Acute diseases: Diseases that last for only very short periods are called acute disease. e.g., common cold chronic diseases: Diseases that last for long time even as much as a life time are called chronic diseases. e.g., elephantiasis
Japanese encephalitis, tuberculosis are chronic diseases.

Q2. State the method of transmission of each of the following diseases:
(a) (i) Cholera 
(ii) AIDS
(iii) Malaria
(iv) Pneumonia
(b) Name the diseases a person will get if the disease causing microbes target the liver of a person.


(a) (i) Cholera — Contaminated water
(ii) HIV-AIDS — Sexual contact
(iii) Malaria — Mosquito/ anopheles female
(iv) Pneumonia — Air

(b) Jaundice

Long Answer Questions (LAQs) : 5 Marks

Q 1.(a) What kind of food is advised when we fall sick and why?
(b) Mention any three basic conditions required for good health.


(a) We should take bland and nourishing food. Such food does not contain fat, oil or spices, so digested easily. It provides sufficient energy and nutrients which are required for recovery and regeneration.

(b) Balanced diet
Personal hygiene
Clean surrounding
Clean food and water
Clean air
Exercises and relaxation
No addiction (Any three)

Q2. Justify the following statements:
(a) “Availability of proper and sufficient food would prevent from infectious diseases”
(b) “The general ways of preventing infection mostly relate to preventing exposure”. List three points of prevention of exposure.


(a) Yes, availability of proper and sufficient food prevents from infectious diseases because functioning of immune system will not be good if proper and sufficient food and nourishment is not available.
(b) Yes, the general ways of preventing infection mostly relate to preventing exposure because:
(i) For air borne microbes, we can prevent exposure by providing living condition that are not over crowded.
(ii) For water borne microbes, we can prevent exposure by providing safe drinking water.
(iii) For vector borne microbes we can prevent exposure by providing clean environment.

Q3. Explain the statement by giving two examples: ‘It is not necessary that the pathogen may affect an organ or tissue depending upon the point of entry’. 


The above statement implies that it is not necessary that, if the pathogen enters the body by different ways, it alters the site and consequence of infection.
For example:
• Suppose HIV virus enters through blood or sexual intercourse person will get HIV.

• If Japanese encephalitis causing virus enters blood through mosquito bite, it reaches brain on infection.

• Herpes simplex virus can enter body orally or through sexual contacts but they affect the body inspite of different point of entry.

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