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1, , Class 9 Science (Biology), Chapter 5 Why do we fall ill, Question 1. State any two conditions for good health, Answer: Two conditions essential for good health are:, , , , State of physical, mental and social well-being., Better surroundings or -environment., , Question 2. State any two conditions essential for being free of disease., Answer. The two conditions essential for being free of disease are:, , , , Personal and -domestic .hygiene., Clean environment and surroundings, , Question 3. What are the different means by which infectious diseases are spread?, Answer: The different means by which infectious diseases spread are:, (a) Through air: They are also called air-borne diseases. The air carries bacteria, virus and the diseases that, can be caused are: common cold, influenza, tuberculosis etc., (b) Through food and water: When one eats/drinks contaminated food/water, that contains bacteria, virus,, worm etc. it can cause diseases like cholera typhoid, hepatitis., (c) Through contact: Many diseases spread by contact of infected person with the healthy person. Example,, fungal infections, skin diseases, scabies etc., (d) By sexual contact: Many diseases can be transmitted, example, syphilis, AIDS., (e) By body fluids: Fluids like blood, semen, mother’s milk, when infected,, can also cause diseases. Example, AIDS., (f) Vectors: The organism that spreads a disease by carrying pathogens from one place to another is called, vector. Example, mosquitoes are vectors that carry pathogens like protozoa., Question 4. What precautions can you take in your school to reduce the incidence of infectious, diseases?, Answer: The precautions that one can take in school to reduce the incidence of infectious diseases are, (a) By using handkerchief while coughing sneezing., (b) Washing hands before eating tiffins., (c) Staying at home if anyone suffers from infectious diseases., (d) Getting vaccinated before the infection affects., (e) Keeping the school surroundings clean, checking for stagnant water., Question 5. What is immunisation?, Answer: When the body attains immunity against any disease, due to vaccination. This process is called, immunisation., Question 6. Write the difference between in following ?, (a) Healthy & Disease free - Page no. 181

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2, , (b) Personal health & Community health - Page no. 183, (c) Acute disease & Chronic disease - Page no. 185, (d) Infectious & non infectious Disease - Page no.187, Question 7. Draw well labelled diagram of some common pathogens ?, Answer : Page no. 188, Question 8. Draw Table of some viral disease & their control & prevention ?, Answer : Page no. 192, Question 9. Draw Table of some bacterial disease & their control & prevention ?, Answer : Page no. 193, Question 10. Draw Table of some vaccines & disease they prevent?, Answer : Page no. 196