NCERT Solutions for Class 9 Science Chapter 13 Why Do We Fall Ill?

Ans : Good health of a person depends on
(i) social environment. (ii) public cleanliness. (iii) good economic conditions and earnings. (iv) social equality and harmony. 

Ans : The conditions essential for being free of diseases (i) Taking good food (balanced diet) (ii) Maintaining personal and public hygiene. 

Ans : The answers are not same all the time. 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. On the other hand, good health for a musician may mean having enough breathing capacity in his/her lungs to control his/her voice. There is one similarity in both the cases. If the conditions essential for good health are maintained, then there are no chances of getting a disease. 

Ans : When there is a disease, its symptoms and signs appear. These symptoms may be headache, cough, loose-motions, wound with pus, etc. These symptoms indicate disease but do not tell what the disease is. So, it is advisable to go to the doctor to diagnose any signs of a disease on the basis of these symptoms. The doctor will get laboratory tests done, if required for the confirmation of a particular disease. 

Ans : Lice and acne will not cause long lasting effects on our body. But in case of jaundice, there will be severe long lasting effects. For example: (i) High temperature, headache and joint pains. (ii) Feeling of nausea and vomiting. (iii) Initiating rashes. The patient will suffer from poor health and will recover by taking complete bed rest for sometime. 

Ans : In case of illness, the normal functions of the body get disturbed. So, a nourishing food is required which is easily digestible and contains all the nutrients. Therefore, bland and nourishing food is advised to take during sickness. 

Ans : Infectious diseases spread by different means. These are: (i) Through air An infected person when sneezes or coughs releases droplets containing germs. These droplets infect another healthy person through air and microbes enter a new body. Examples of such diseases are common cold, pneumonia and tuberculosis. (ii) Through water If the water source is polluted by the excreta of infectious persons having gut diseases and this water is used by other people they will be infected by diseases. For example, cholera, amoebiasis, hepatitis spread through water. (iii) Through sexual contact Some diseases like AIDS and syphilis, etc., are transmitted by sexual contact. Other than this, AIDS virus also spread through blood, infected syringes, infected mother to her baby during pregnancy and through breast feeding. (iv) Through vectors There are some animals which act as intermediaries or vectors for a particular diseases.  The vectors carry diseases from infected person to the healthy person. For example, mosquito spread malaria causing organism in humans, while sucking their blood. 

Ans : To prevent the incidence of infectious diseases in school following precautions can be taken: (i) Avoid contact of students suffering from air borne diseases like common cold, cough, eye, flu, etc. (ii) By checking the availability of clean drinking water in school. (iii) Clean surroundings in school will not allow the growth and multiplication of vectors. (iv) Starting childhood immunisation programme in schools. 

Ans : Immunisation is a process of administration (injecting) of vaccine into a healthy person in order to develop immunity against a disease. Immunity means the ability of a body to recognise, destroy and eliminate external disease causing agents. This immunisation through administering vaccine is called vaccination. Vaccine contains disease-causing organisms in a diluted or weakened form or in living or dead form. It prevents further infection by microbes from causing the disease. The diseases like smallpox, rabies, diphtheria chicken pox, polio, hepatitis are controlled by vaccination. Smallpox is eliminated from the world through a worldwide vaccination programme. 

Ans : The following immunisation programme is available at the nearest health centre in our locality (i) Immunisation for infants—DPT, BCG, polio, measles and MMR. (ii) For children—Typhoid, TT, DT, smallpox and TAB. (iii) For pregnant women— TT and hepatitis-B. The diseases like typhoid, polio, measles, tetanus are the major health problems in our locality. To prevent these diseases, our government have initiated expanded immunisation programme all over the country. 

Ans : DIY 

Ans : A doctor/nurse/health worker is exposed to more sick people in the community. He/she  avoids getting sick by: (I) keeping place of work sterilized by using phenyl etc. (ii) keeping equipments, that are regularly in use, sterilized. (iii) washing hands with soap thoroughly after serious examination of patients. (iv) getting themselves vaccinated against various diseases. 

Ans : After conducting a survey in my neighborhood, I found out that the three most common diseases in my area are diarrhea, malaria, and typhoid. Three steps that could be taken by local authorities to bring down the incidences of these diseases are: (i) proper disposal of garbage and regular cleaning of roads and streets. (ii) regular cleaning of drains and spraying of insecticides. (iii) provision of clean drinking water. 

Ans : (a) Symptoms that help us to find that baby is sick, are (i) Continuous crying and restlessness of the child (ii) Improper intake of food and body temperature.
(b) Kind of sickness can be known by certain organ-specific and tissue-specific symptoms e.g., yellowness of skin and eyes indicate the jaundice and hepatitis. 

Ans : A person is most likely to fall sick in (c) condition because malaria attack has caused large scale destruction of her blood cells so she is weak and anemic. Then she is on a four-day fast so is not getting proper and sufficient food which further decreases the functioning of her immune system and lastly chickenpox is a communicable and contagious disease. 

Ans : I will be most likely to fall sick when my friend is suffering from measles and I come in contact with him because measles is contagious disease and also spreads by droplet infection.