why do we fall ill? notes class 9th

 Question 1.

State any two conditions essential for good health.
Solution:

• Better sanitation or clean surroundings
• Good economic conditions.

Question 2.
State any two conditions essential for being free of disease.
Solution:

• Living in hygienic environment.
• Getting vaccinated against common infectious diseases.

Question 3.
Are the answers to the above questions (2 and 3) necessarily the same or different? Why?
Solution:
Answers to above questions are interconnected but different. It is so because being disease free does not mean one is healthy.

Question 4.
List any three reasons why you would think that you are sick and ought to see a doctor. If only one of these symptoms were present, would you still go to the doctor ? Why or why not?
Solution:
The three reasons of feeling sick and to go to see a doctor are as follows :

• having body temperature,
• having diarrhoea (loose motions), and
• having cough/cold.

If only one symptom persists, then also one should go to a doctor. The doctor will diagnose on the basis of the symptoms. Doctor will also get laboratory tests done to pin point the disease further.

Question 5.
In which of the following case do you think the long-term effects on your health are likely to be most unpleasant ?
(a) If you get jaundice,
(b) If you get lice,
(c) If you get acne. Why?
Solution:
In case of attack of jaundice, there would be long-term effects on my body. It is so because jaundice is a disease in which liver is affected. It takes more time to recover from this disease. On the other hand, lice can be removed easily with short treatment and so is the acne. Both these do not produce long¬term effects on the body.

Question 6.
Why are we normally advised to take bland and nourishing food when we are sick?
Solution:
Bland food is soft and can be easily digested and assimilated in body. Nourishing food increases resistance for disease and is essential for repair and growth of body tissue.

Question 7.
What are the different means by which infectious diseases are spread ?
Solution:
Infectious diseases are generally spread through air, water, sexual contact, vectors, physical contact with affected person and through articles of use of affected person.

Question 8.
What precautions can you take in your school to reduce the incidence of infectious diseases?
Solution:
Following precautions can be taken in the school to reduce the incidence of infectious diseases :

• Providing clean drinking water,
• Educating students about causes of infectious diseases, .
• Vacccination of students against common infectious diseases from time to time,
• Proper sanitation or clean environment in school and its surroundings to eradicate vectors of infectious diseases, and
• By not allowing the affected students to attend the classes till they recover from infectious diseases.

Question 9.
What is immunisation ?
Solution:
Immunisation is a technique in which people are given particular vaccine so that they develop temporary/permanent immunity against a particular infectious disease. In other words, immunisation is a specific way of preventing infectious diseases.

Question 10.
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 ?
Solution:
Immunisation programmes are as follows :

• BCG vaccination against tuberculosis
• Polio drops against polio disease
• Vaccination against chicken pox
• Vaccination against hepatitis
• DPT vaccination against diphtheria, pertussis (Whooping cough) and tetanus.
• Immunisation against measles.

Major health problems are :

• Hepatitis
• Chicken-pox
• Tuberculosis
• Polio.

NCERT Exercises

Question 1.
How many times did you fall ill in the last one year? What were the illnesses?
(a) Think of one change you could make in your habits in order to avoid any of/most of the above illnesses.
(b) Think of one change you would wish for in your surroundings in order to avoid any of/ most of the above illnesses.
Solution:
I suffered last year from cough and cold (twice) and malaria (once).
(a) Change in habits : Wear suitable clothes in order to give protection to the body during changing season and against mosquito bite.
(b) Change in surroundings :

• Improve the sanitary conditions in the surroundings,
• Do not allow water to collect near the houses, because it provides the breeding ground for mosquitoes.

Question 2.
A doctor/nurse/health-worker is exposed to more sick people than others in the community. Find out how she/he avoids getting sick herself/ himself.
Solution:
A doctor/nurse/health worker is exposed to more sick people in the community. He/she avoids getting sick by:

• keeping place of work sterilised by using phenyl etc.
• keeping equipments, that are regularly in use, sterilised.
• washing hands with soap thoroughly after serious examination of patients.
• getting themselves vaccinated against various diseases.

Question 3.
Conduct a survey in your neighbourhood to find out what the three most common diseases are. Suggest three steps that could be taken by your local authorities to bring down the incidence of these diseases.
Solution:
After conducting a survey in my neighbourhood, I found out that the three most common diseases in my area are diarrhoea, malaria and typhoid. Three steps that could be taken by local authorities to bring down the incidences of these diseases are :

• proper disposal of garbage and regular cleaning of roads and streets
• regular cleaning of drains and spraying of insecticides
• provision of clean drinking water.

Question 4.
A baby is not able to tell her/his caretakers that she/he is sick. What would help us to find out
(a) that the baby is sick?
(b) what is the sickness?
Solution:
(a) Symptoms that help us to find that baby is sick, are :

• Continuous crying and restlessness of the child
• Improper intake of food and body temperature.

(b) Kind of sickness can be known by certain organ-specific and tissue-specific symptoms for e.g., yellowness of skin and eyes indicate the jaundice and hepatitis.

Question 5.
Under which o’, the following conditions is a person most likely to fall sick ?
(a) When she is recovering from malaria.
(b) When she has recovered from malaria and is caking care of someone suffering from chicken-pox.
(c) When she is on a four-day fast after recovering from malaria and is taking care of someone suffering from chicken-pox. Why?
Solution:
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 anaemic. Then she is on a four- day fast and not getting proper and sufficient food which further decreases the functioning of her immune system and lastly chickenpox is a communicable and contagious disease.

Question 6.
Under which of the following conditions are you most likely to fall sick ?
(a) When you are taking examinations.
(b) When you have travelled by bus and train for two days.
(c) When your friend is suffering from measles. Why?
Solution:
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.

short answer questions 

Question 1.
What are the constituents of a balanced diet?
Answer:
Constituents of a balanced diet are as follows:

• Carbohydrate: It provides 50-70% of total energy intake.
• Fat: For an adult, fat should provide 20% of total energy intake. Children require more fat so as to suffice 50% of the total energy intake.
• Proteins: Protein intake should be about 15-20% of the total daily energy intake.
• Vitamins and minerals
• Water
• Roughage

Question 2.
Write four common symptoms of malaria.
Answer:

• Sudden appearance of fever with pain and sensation of cold shivering.
• Body temperature rises up to 106°F and patient becomes burning hot. He or she experiences intense headache, faster breathing rate and heart beat.
• Fever later comes down with profuse sweating. This occurs either daily at a particular time or is repeated every third or fourth day depending upon the species of the parasite.
• Enlargement of spleen and anaemia occurs.

Question 3.
Write the distinct species of malarial parasite in man.
Answer:
Malaria in man is caused by four distinct species of malarial parasites:

• Plasmodium vivax: incubation period in human is 8-17 days.
• P. falciparum: incubation period in human is 9-14 days.
• P. malariae: incubation period in human is 18-40 days.
• P. ovale: incubation period in human is 16-18 days.

Question 4.
What is the difference between being ‘healthy’ and ‘disease-free’?
Answer:
A person is said to be healthy when:

• All the organs and systems of the body are intact and working well.
• One is mentally balanced, free from anxieties and tensions.
• One is socially well-adjusted in the family, friends and society.

Whereas being ‘disease-free’ means absence of any body discomfort. Thus, being healthy is not just freedom from disease.

Question 5.
What are the immediate and contributory causes of diseases? Explain it with the example of a child suffering from diarrhoea.
Answer:
Immediate cause of a disease is the primary factor causing a disease. Contributory causes are factors, which do not cause the disease themselves but provide conditions for the disease to occur. Virus causing diarrhoea is the immediate cause. Contaminated drinking water and lack of resistance due to under-nourishment are the contributory causes.

Question 6.
Write the symptoms when following organs are targeted by microbes.
(a) Lungs
(b) Liver
(c) Brain
Answer:
(a) Lungs — cough, breathlessness
(b) Liver —jaundice
(c) Brain — headache, vomiting, fits.

Question 7.
Enlist the cause of diseases.
Answer:
Disease may be caused due to any of the following reasons:

• infection
• Lack of nutritive and sufficient food
• Poor health
• Lack of public services
• Hereditary reasons.

Question 8.
Describe health care.
Answer:
Health care is provided to vast majority of poor, rural and urban people through effective health care centres. Health care services provide different types of care at primary health care centre and ‘ secondary health care centers.
Primary health care is provided by the primary health centres established in small towns and villages, through the agency of health workers, village health guide and trained dhayas.
Secondary health care deals with more complex problems. It is generally provided in district hospitals and community health centers.

Question 9.

What determines the severity of disease manifestation?
Answer:
The number of disease-causing microbes in the body decide the severity of disease manifestation. If the number of microbes is very small, the disease manifestations may be minor and even go unnoticed. But if the number of microbes is large, the disease can be severe. In fact if the number of microbes is very large, the disease can even be fatal. Our immune system is a major factor that determines the number of microbes surviving in the body.

Question 10.
Differentiate between communicable and non-communicable diseases.
Answer:

Communicable Diseases	Non-communicable Diseases

1. These diseases can be transmitted from an infected person to a healthy person.

1. These diseases cannot be transmitted.

2. These are spread by microorganisms called pathogens.	2. These are caused by deficiency of nutrients or hormone, tumour formation, etc.
3. e.g., Cholera, influenza, AIDS, malaria, etc.	3. e.g., Diabetes, marasmus, goitre, cancer, etc.

Question 11.
Name the infectious disease that leads to immunodeficiency. Give the scientific name of the pathogen causing the disease and mention the body organs it primarily affects.
Answer:
AIDS is an infectious disease that leads to immune deficiency and wasting of body parts. It is caused by Human Immunodeficiency Virus (HIV). HIV attacks helper T-lymphocytes, thus causing cell-mediated immunodeficiency, which makes the body more prone to various infections.

Question 12.
Name fat-soluble vitamins and diseases caused by them.
Answer:
Fat-soluble vitamins include vitamin A, D, E and K.

Vitamin	Deficiency Diseases
A	Xerophthalmia, night-blindness, keratomalacia
D	Rickets in children, osteomalacia in adults
E	Anaemia
K	Bleeding disease

Question 13.
What are the causes and symptoms of goitre?
Answer:
Goitre is caused due to deficiency of iodine in the diet.
Symptoms of goitre are as follows:

• Abnormal growth of thyroid gland situated in the front part of the neck.

• Increase in body weight due to accumulation of fat and retention of water in the body.
• Increased rate of spontaneous abortion and still birth.
• Disorder in nervous system. Iodine deficiency in childhood causes reduced functioning of the thyroid gland resulting in retarded growth.

Question 14.

What are the sources of iodine? What are the prevention and control methods of goitre.
Answer:
Sources of iodine: T he best sources of iodine are sea foods and cod liver oil. A smaller amount of iodine occurs in milk, leafy vegetables, cereals and meat, etc. Iodised salt contains sufficient amount of iodine.

Prevention and control of goitre: It can be prevented by providing iodine in the diet in the form of iodised salts, such as potassium iodate and potassium iodide. These can be added in drinking water or in common salt used daily. Intra-muscular injection of iodised oil or sodium iodide tablets developed by Indian Council of Medical Research is quite effective in curing goitre.

Question 15.
What are the indirect modes of transmission of infectious diseases?
Answer:
Indirect transmission occurs through flies, food and fluid, etc. Infectious agents are transmitted through water and food including vegetable, fruits, milk, milk products, ice, blood serum, plasma, etc. Their transmission is vehicle-borne. Some examples are as follows:

2. Diarrhoea, typhoid fever, polio, cholera	Transmitted by water and food
3. Hepatitis B, malaria, syphilis, chagas disease	Transmitted by vectors

Question 16.
What are the common preventive measures against communicable diseases?
Answer:
The common preventive measures against communicable diseases include:

• Eradication of vectors and carriers.
• Immunisation (vaccination).
• Proper and safe water supply.
• Personal and community hygiene.
• Sterilisation of articles used by the patients.
• Isolation of patients from the healthy persons.
• Health education.

Question 17.
Name the diseases caused by the following—

• Protozoa,
• Virus,
• Bacteria,
• Fungi. How is malaria transmitted?

Answer:
The diseases caused by various microorganisms are as follows:

• Protozoa: Malaria, amoebiosis, dysentery, giardiasis, kala-azar, etc.
• Virus: AIDS, polio, dengue, rabies, chicken pox, influenza, etc.
• Bacteria: Pneumonia, diphtheria, tuberculosis, meningitis, leprosy, typhoid, tetanus, syphilis, etc.
• Fungi: Fungi mainly causes skin diseases and food poisoning.

Malaria is caused by a parasite found in female Anopheles mosquitoes. When the mosquitoes carrying the malarial parasite bite a person, the parasite enters the blood stream and the person suffers from malaria.

Question 18.
What are the three limitations which one has to face while dealing with an infectious disease?
Answer:
The three limitations which one has to face while dealing with an infectious disease are:

• The body functions are damaged drastically and may never recover completely if not cared.
• The treatment will take time, which means that someone suffering from a disease is likely to be bed-ridden for sometime.
• The person suffering from an infectious disease can serve as a source from where the infection may further spread to other people.

Question 19.
What is immunity? Explain natural and acquired immunity.
Answer:
Immunity means the resistance of the body to a disease. It is due to the presence of antibodies in our body against the disease-causing microorganisms known as antigens. When these antigens enter our body, antibodies are formed which prevent the disease.

Natural immunity means that a person has these antibodies since birth, e.g., whenever antigens, say of cholera enter the body, the person will not suffer from the disease.

Acquired immunity means when a person suffers from a disease once, antibodies for these particular disease-causing antigens will be formed in the body and he will not get the same disease again.

Question 20.
Give an example where tissue specificity of the infection leads to very general seeming effects.
Answer:
We can see the tissue specificity of the infection leading to very general seeming effects in case of HIV infection. The HIV attacks the immune system via the lymph nodes. From here it spreads all over the body and damages its functions. Because of this, the body becomes prone to various diseases as it cannot fight off even the minor infections which otherwise would not have lasted longer.

For example, even a small cold can become pneumonia and a minor gut infection may lead to a severe case of diarrhoea with blood loss.
In the same way, other infections kill people that are suffering from, e.g., HIV-AIDS.
The tissue specificity of the infection (HIV-AIDS) is lymph nodes. General seeming effects are loss of immunity even to minor diseases or infections that ultimately lead to the death of the patient.

Question 21.
What precautions will you take to justify “prevention is better than cure”? [NCERT Exemplar]
Answer:
Following precautions should be taken for prevention of diseases:

• Maintaining hygienic conditions.
• Awareness about the disease and its causal organism.
• Intake of a balanced diet.
• Regular medical check-up.

Question 22.
Give any four factors necessary for a healthy person.
Answer:
For a healthy person it is necessary that

• the surrounding environment should be clean. Air and water-borne diseases should not spread.
• personal hygiene is maintained to prevent infectious diseases.
• proper, sufficient nourishment and food is available for good immune system of our body.
• body is immunised against severe diseases.