RBSE Class 9 Science Important Questions Chapter 13 Why Do We Fall Ill

Rajasthan Board RBSE Class 9 Science Important Questions Chapter 13 Why Do We Fall Ill Important Questions and Answers.

RBSE Class 9 Science Chapter 13 Important Questions Why Do We Fall Ill

Objective Type Questions

Question 1.
Which one of the following is not a viral disease?
(a) Dengue
(b) AIDS
(c) Typhoid
(d) Influenza
Answer:
(c) Typhoid

Question 2.
Which one of the following is not a bacterial disease?
(a) Cholera
(b) Tuberculosis
(c) Anthrax
(d) Influenza
Answer:
(d) Influenza

Question 3.
Which one of the following diseases is not transmitted by mosquito?
(a) Brain fever
(b) Malaria
(c) Typhoid
(d) Dengue
Answer:
(c) Typhoid

Question 4.
Which one of the following diseases is caused by bacteria?
(a) Typhoid
(b) Anthrax
(c) Tuberculosis
(d) Malaria
Answer:
(d) Malaria

Question 5.
Which one of the following diseases is caused by protozoans?
(a) Malaria
(b) Influenza
(c) AIDS
(d) Cholera
Answer:
(a) Malaria

Question 6.
Which one of the following has a long term effect on the health of an individual?
(a) Common cold
(b) Chickenpox
(c) Chewing tobacco
(d) Stress
Answer:
(c) Chewing tobacco

Question 7.
Which one of the following can make you ill if you come in contact with an infected person?
(a) High blood pressure
(b) Genetic abnormalities
(c) Sneezing
(d) Blood cancer
Answer:
(c) Sneezing

Question 8.
AIDS cannot be transmitted by:
(a) Sexual contact
(b) Hugs
(c) Breastfeeding
(d) Blood transfusion
Answer:
(b) Hugs

Question 9.
Which one of the following causes kala-azar?
(a) Ascaris
(b) Trypanosoma
(c) Leishmania
(d) Bacteria
Answer:
(c) Leishmania

Question 10.
If you live in a over-crowded and poorly ventilated house, it is possible that you may suffer from which of the following diseases?
(a) Cancer
(b) AIDS
(c) Air-borne diseases
(d) Cholera
Answer:
(c) Air-borne diseases

Question 11.
Which disease is not transmitted by mosquitoes?
(a) Dengue
(b) Malaria
(c) Brain fever or encephalitis
(d) Pneumonia
Answer:
(d) Pneumonia

Question 12.
Which one of the following is not important for individual health?
(a) Living in clean space
(b) Good economic condition
(c) Social equality and harmony
(d) Living in a large and well furnished house
Answer:
(d) Living in a large and well furnished house

Question 13.
We should not allow mosquitoes to breed in our surroundings because they :
(a) multiply very fast and cause pollution.
(b) are vectors for many diseases.
(c) bite and cause skin diseases.
(d) are not important insects.
Answer:
(b) are vectors for many diseases.

Question 14.
Viruses, which cause hepatitis, are transmitted through :
(a) air
(b) water
(c) food
(d) personal contact
Answer:
(b) water

Question 15.
Vectors can be defined as :
(a) Animals carry the infecting agents from sick person to another healthy person
(b) Microorganisms which cause many diseases
(c) Infected person
(d) Diseased plants
Answer:
(a) Animals carry the infecting agents from sick person to another healthy person

Question 16.
Which one of the following is a long-term disease?
(a) Cough
(b) Fever
(c) Common cold
(d) Athlete foot
Answer:
(d) Athlete foot

Question 17.
Which one of the following disease damages body’s immunity system?
(a) Malaria
(b) HIV virus
(c) Cancer
(d) T.B.
Answer:
(b) HIV virus

Question 18.
Headache, vomit and unconsciousness are symptoms of which part of body getting affected?
(a) Brain
(b) Lungs
(c) Kidney
(d) Heart
Answer:
(a) Brain

Question 19.
Symptom showing infection of lungs:
(a) Dizziness
(b) Vomiting
(c) Coughing
(d) All of these
Answer:
(c) Coughing

Question 20.
Leishmania protozoa causes which of the following disease?
(a) Kala-azar
(b) Ache
(c) Sleepiness
(d) Malaria
Answer:
(a) Kala-azar

Question 21.
Pathogen of peptic ulcer is:
(a) Virus
(b) Bacteria
(c) Protozoa
(d) Worm
Answer:
(b) Bacteria

Question 22.
Disease that can be transmitted from an infected woman to her infant is:
(a) Athlete foot
(b) AIDS
(c) Malaria
(d) All of these
Answer:
(b) AIDS

Question 23.
Vector that carries malaria disease is :
(a) Dog
(b) House fly
(c) Mosquito
(d) Protozoa
Answer:
(c) Mosquito

Question 24.
Fill in the blanks:
(a) .................. disease continues for many days and causes .............. on body.
(b) .................. disease continues for a few days and causes no long term effect on body.
(c) .................. is defined as physical, mental and social well-being and comfort.
(d) Common cold is .................. disease.
(e) Many skin diseases are caused by ..................
Answer:
(a) Chronic, long term effect
(b) Acute
(c) Health
(d) communicable (infectious)
(e) fungi

Question 25.
Match the column (A) with the column (B).

Column (A)	Column (B)
(i) Malaria	(a) Protpzoa
(ii) AIDS	(b) Worm
(iii) Tuberculosis	(c) Virsus
(iv) Athlete foot	(d) Bacterip

Answer:

Column (A)	Column (B)
(i) Malaria	(a) Protpzoa
(ii) AIDS	(c) Virsus
(iii) Tuberculosis	(d) Bacterip
(iv) Athlete foot	(b) Worm

Question 26.
Match the column (A) with the column (B).

Column (A)	Column (B)
(i) Tuberculosis	(a) Brain
(ii) Hepatitis	(b) Liver
(iii) Japanese brain fever	(c) Lungs
(iv) Malaria	(d) RBCC (Blood)

Answer:

Column (A)	Column (B)
(i) Tuberculosis	(c) Lungs
(ii) Hepatitis	(b) Liver
(iii) Japanese brain fever	(a) Brain
(iv) Malaria	(d) RBCC (Blood)

Question 27.
Read the statements carefully and identify whether they are True or False-
1. Sexually transmitted disease spread through normal contact.
2. High blood pressure is caused by heavy weight and no exercise.
3. Making anti-viral medicines is easier than making anti-bacterial medicines.
4. Beri beri is caused by the deficiency of vitamin - B1 in diet.
5. Acute diseases are long term diseases.
Answer:
1. False
2. True
3. False
4. True
5. False

Very Short Answer Type Questions

Question 1.
Name any two groups of microorganisms from which antibiotics could be extracted.
Answer:
Bacteria and fungi.

Question 2.
What is the work of vaccination?
Answer:
Vaccination is to grow the production of specific antibodies to confer immunity against subsequent infection.

Question 3.
Name the microorganism causing elephantiasis.
Answer:
Worms.

Question 4.
Many vaccines form the public health programme of childhood immunisation for preventing infectious disease. Name any two such diseases.
Answer:

1. Vaccine against measles.
2. BCG vaccine against T.B.

Question 5.
What is an epidemic disease?
Answer:
An epidemic is the rapid and extensive spread of disease that affects many individuals simultaneously in a particular area. It is generally an infectious disease.

Question 6.
Name any two diseases which are caused due to unprotected sexual intercourse.
Answer:

1. AIDS
2. Syphilis

Question 7.
How can we prevent water-borne and vector-borne infections?
Answer:

• Water borne infections can be prevented by providing safe drinking water.
• Vector borne infections can be prevented by providing clean environment.

Question 8.
Name the pathogens which can cause acne and sleeping sickness.
Answer:
Acne - Staphylococci.
Sleeping sickness - Trypanosoma.

Question 9.
Name any four diseases transmitted through vectors.
Answer:
Malaria, dengue, kala-azar and plague.

Question 10.
Give any four essential factors that must be taken care of by an individual for keeping good health.
Answer:

1. Balanced diet
2. Healthy environment
3. Personal hygiene
4. Mental and social stability

Question 11.
What causes Japanese encephalitis? How it can be prevented?
Answer:

• Japanese encephalitis is caused by virus which enters into human body through mosquito bite.
• By keeping the surrounding dean and taking proper measures against mosquito bite, it can be prevented.

Question 12.
Write the expanded form of AIDS.
Answer:
Acquired Immuno Deficiency Syndrome.

Question 13.
Why do female anopheles mosquito feed on human blood?
Answer:
They need nutritious food in the form of blood in order to be able to lay mature eggs.

Question 14.
Why are we normally advised to take bland and nourishing food when we are sick?
Answer:
Normal body functions get disturbed during disease. In such a case, nutritious and easily digestible food is good for fast recovery. Thus, bland and nourishing food is required during sickness.

Question 15.
What are the symptoms shown by a person if:
(i) Lungs get infected,
(ii) Stomach is infected?
Answer:
(i) Cough and breathlessness.
(ii) Stomach ache, loose motion, vomiting.

Question 16.
What are the common methods of transmission of disease?
Answer:
Disease can be spread from infected person to healthy person by means of water, air, food, insect, physical contact.

Question 17.
Name one disease caused when the microbes target, lungs and liver.
Answer:
Lungs - Asthma
Liver - Jaundice

Question 18.
Name the causal organism of AIDS. Why a person suffering from AIDS cannot fight even very minor infections?
Answer:
HIV is the causal organism of AIDS. This virus goes to the human immune system, thus can damage the bodily function. So, the body can no longer fight off even very minor infections.

Question 19.
How does public cleanliness affect our health?
Answer:
Public cleanliness is important for our health. If someone is living in a filthy neighbourhood, he has a greater risk of being affected by some or the other epidemic.

Question 20.
What do you understand by disease?
Answer:
A condition in which the affected person is unable to carry out normal activities is termed as disease.

Question 21.
What is an antibiotic?
Answer:
A substance which stops the growth of bacteria or kills the bacteria is called antibiotic. Antibiotic is given to treat or prevent bacterial infection.

Question 22.
What are vectors for a disease?
Answer:
Some animals work as vehicles to transfer infection from one person to another. Such animals are called vectors.

Question 23.
Which animal plays the role of vector for malaria?
Answer:
Female Anopheles mosquito.

Question 24.
Which animal plays the role of vector for rabies?
Answer:
Dogs, cats, mongoose, monkey.

Question 25.
Why does intake of penicillin not affect human cells?
Answer:
It is because penicillin blocks cell wall and formation of biochemical pathways in bacteria. Human cells do not have cell wall, thus remain unaffected.

Question 26.
You have suffered from chickenpox, when you were in class three. Why will you not suffer from it again?
Answer:
As I suffered from chickenpox^ when I were in class three. I got well by cure.
Now, my immune system has developed antibodies against it.

Question 27.
Why is AIDS a fatal disease?
Answer:
In AIDS, immune system of the body is highly weakened and body suffers from severe infections which lead to death of the individual. Hence, it is a fatal disease.

Question 28.
Common cold spreads faster and is difficult to control. Give reason.
Answer:
Common cold is a communicable and air-borne disease, i.e. the microbes spread through the air. Thus, common cold spreads faster and is difficult to control.

Question 29.
Why making anti-viral medicines is harder than making anti-bacterial medicines?
Answer:
Antibiotics block the biochemical pathways important for bacteria which inhibit growth of bacteria or kill them. However, viruses do not use biochemical pathways like bacteria. Hence, these remain unaffected by antibiotics.

Question 30.
What is Incubation Period?
Answer:
It is the period between the infection and the appearance of the first symptom.

Question 31.
Which was the first Antibiotic?
Answer:
Penicillin was the first antibiotic which was invented by Alexander Fleming in 1928.

Question 32.
Which is the most common type of plague?
Answer:
Bubonic Plague is the most common type of Plague.

Question 33.
Which vaccine was discovered for the first time and who discovered it?
Answer:
Edward Jenner invented the vaccine for the first time and it was of smallpox.

Question 34.
What are non-communicable diseases? Give examples.
Answer:
Those diseases which cannot be spread from person to person, e.g. Diabetes, Cancer, etc.

Question 35.
Why is vaccination of children necessary?
Answer:
Children are more vulnerable and susceptible to diseases and are hence given vaccines so they are able to develop immunity against diseases.

Short Answer Type Questions

Question 1.
Differentiate between acute disease and chronic disease.
Answer:

Acute Disease	Chronic Disease
1. Last for short period of time.	1. Chronic diseases last for a long period of time.
2. It is caused randomly.	2. It is in due course of time.
3. Does not have major effect on general health.	3. Major effect on general health.
4. Example: Cough, dysentery.	4. Example: Heart disease, tuberculosis.

Question 2.
Give difference between acquired disease and congenital disease.
Answer:

Acquired Disease	Congenital Disease
1. Acquired after birth during life-span.	1. Present from birth.
2. Inherited.	2. These are inherited.
3. Caused by pathogens or nutritional deficiency.	3. Caused by gene mutations.

Question 3.
(i) Why a person suffering from AIDS cannot fight even small infections?
(ii) In a slum area, many people are suffering from malaria. Mention any two unhygienic conditions that must be prevailing in that locality.
Answer:
(i) AIDS is caused by HIV which damages the immune system of the person suffering from it. Thus, the person cannot fight even small infections.
(ii) Stagnant water in the surroundings and accumulation of garbage.

Question 4.
Name five diseases against which immunisation vaccine are available.
Answer:
Five diseases against which immunisation vaccines are available :

1. Tetanus
2. Diphtheria
3. Whooping cough
4. Polio
5. Measles

Question 5.
State the principle of immunisation.
Answer:
Immune system responds against infectious microbes after detecting it first time. If this microbe again enter in body, immune system respond vigorously. This eliminate the infection more quickly than the first time. This is the principle of immunisation.

Question 6.
State two principles of treatment of a disease. Name the approaches generally adopted to treat infectious diseases.
Answer:
There are two ways to treat an infectious disease:

1. Reducing the effect of the disease.
2. Killing the microorganisms that act as infectious agents.

There is two approaches to treat the infectious diseases. These are:

1. To reduce the effects of the disease.
2. To eliminate or kill the cause of the disease.

Question 7.
What are limitations for the approach to deal with infectious diseases?
Answer:
Three limitations are :

• If someone is suffering from disease, his body function will disturb.
• Treatment will take time.
• Infectious person can be a source of spreading infection.

Question 8.
Give difference between Kwashiorkor and Marasmus.
Answer:

Kwashiorkor	Marasmus
1. Due to deficiency of protein in diet.	1. Due to deficiency of protein, carbohydrate and fat.
2. Child shows oedema in lower legs, lower arm and face.	2. No swelling
3. Poor appetite	3. Usually good appetite
4. Irritable, apathetic	4. Quiet and apathetic
5. Occurs in children from 1 to 5 years.	5. Occurs in infants upto one year of age.

Question 9.
Why can we not make antiviral drugs?
Answer:
The viruses lie on the border of living and non-living organism. The virus needs a host body to live and multiply. They cannot be grown and their biological pathways cannot be affected. Hence, the anti-viral drugs is difficult to make.

Question 10.
What do you mean by immune response?
Answer:
Immune response is the reaction of the body’s immune system to foreign cells or substances that cause disease or may even be potentially dangerous. This response involves the production of cells (lymphocytes) and chemicals (antibodies) designed to defend the body against the pathogen.

Question 11.
Name the diseases which are caused by :
Answer:
Bacteria: TB, Typhoid, Anthrax and Tetanus.
Viruses: Common Cold, AIDS, Dengue fever and Mumps.
Fungi: Ringworm, Skin infections and Athlete’s foot.
Protozoa: Malaria, Kala-azar, Sleeping sickness and Amoebiasis.

Question 12.
What is inflammation? What are the symptoms and sign of inflammation?
Answer:
It is the recruitment process by immune system in which immune system recruits many cells to the affected tissue to kill the disease causing germs. During this process, certain local effects such as swelling and pain and general effects such as fever may develop.

Question 13.
Define carriers. Give two examples.
Answer:
Carriers are the organisms which harbor disease-causing germs without showing away sign of disease themselves, but have the ability to infect other healthy individuals.
For example: Housefly, female insect Anopheles.

Question 14.
The body of a patient has lost its power of fighting against infections. Which disease may the patient be suffering from? Name the pathogen and describe any two modes of its transmission from the patient to other person.
Answer:
Patient is suffering from AIDS.
HIV (Human Immunodeficiency Virus) can be transmitted by :

• sexual contact with infected person.
• the use infected syringe.

Question 15.
What are the various dimensions of health?
Answer:
Various dimensions of health is:

• Physical dimensions: Physical health implies perfect functioning of all the organs and systems of the body.
• Mental dimensions: Mental health implies a state of balance and harmony between the individual and surrounding world.
• Social dimensions: A person is socially healthy if he has a good job, a good house, a happy family, good neighbours and understanding friends.

Question 16.
What are the causes of diseases?
Answer:
Causes of diseases are:

• Infection by microorganisms - bacteria, virus, fungi, protozoa and worms cause communicable diseases.
• Malfunctioning of body organs.
• Deficiency of one or more nutrients.
• Genetic factors.
• Polluted environment.

Question 17.
What are the conditions favouring air-bone diseases?
Answer:
Conditions favouring air-borne infections :

• Close proximity to the infected person.
• Over-crowding.
• Poor-ventilation.

Question 18.
What are the different types of diseases? Explain them.
Answer:
Diseases are broadly grouped into two types :
Communicable or infectious diseases: Those diseases which are passed on from one person to another in various ways through air, water, food, physical contact and insects.

Non-communicable diseases: Those diseases which cannot be spread from person to person. For example : Arthritis, marasmus, etc.

Question 19.
What is immunisation, immune system, immunity?
Answer:

• Immunisation is a specific method of preventing diseases by inoculating vaccines in the human body.
• Immune system: It is a system which protect our body against infection.
• Immunity: The body’s power to resist and overcame infection is called immunity.

Question 20.
What do signs and symptoms indicate if a person is suffering from any disease?
Answer:
Signs and symptoms indicate presence of a particular disease. Because when there is a disease, either the functioning or the appearance of one or more systems of the body will change for the worse.

Question 21.
Give four modes of transmission of AIDS.
Answer:

• Blood to blood contact (transfusion).
• From an infected mother to her unborn baby during pregnancy, labour or delivery.
• Through breastfeeding.

Question 22.
Write a short note on vaccination.
Answer:
Vaccination is based on the principle that our body learns to fight against a certain microbe when the microbe attacks our body for the first time. Vaccines are made from dead or weak strains of a microbe. Vaccine is inoculated in the body in appropriate dose. After vaccination, the body learns to fight with that microbe. As a result the body fight back strongly to prevent disease.

Question 23.
How can we prevent air-borne diseases?
Answer:
Air-borne disease can be prevented by some simple measures. If you are suffering from common cold then you should cover your face while sneezing or coughing. In case of a flu scare in the city, you should wear a face -mask while going to a public place or traveling by public transport. Our body easily wards off any future onslaught of that microbe. Many diseases can be prevented by vaccines.

Question 24.
What do you mean by active and passive immunisation?
Answer:
Active immunisation: It promotes the production of circulating antibodies against foreign antigens by injecting a small quantity of modified antigen into the bloodstream.

Passive immunisation: It is the application of antibodies from an immune individual to non-immune patient. This treatment is used when an individual has been or probably will be, exposed to an infectious disease and there is insufficient time for active immunisation.

Question 25.
How can we prevent water-borne diseases?
Answer:
Water-borne diseases can be prevented by avoiding the use of contaminated water. You should always carry drinking water from home. If that is not possible then you should buy bottled water for drinking. Never buy food from those vendors who do not keep their food items covered. Don’t eat stale or spoiled food items.

Question 26.
What do you understand by non-infectious disease?
Answer:
When a disease happens because of some malfunctioning in any organ and it is not because of any microorganism, it is called non-infectious disease. A non-infectious disease may happen because of a wrong lifestyle. Some non-infectious diseases may happen because of genetic factor, i.e. they are right from the birth. Example: Diabetes, hypertension, heart disease, arthritis, hemophilia, etc.

Question 27.
What is an infectious disease?
Answer:
When a disease happens because of a microorganism, it is called infectious disease. Bacteria, protozoa, virus and fungi are the causes of diseases in this case. Example: Diarrhoea, tuberculosis, dengue, malaria, hepatitis, etc.

Question 28.
State conditions essential for good health.
Answer:
Health is a state of being well enough to function well physically, mentally and socially. The health of any individual depends upon :

• Better social environment.
• Better public cleanliness.
• Good economic conditions.
• Social equality and harmony.

Question 29.
Give the modes of transmission of each of the following diseases :
(i) Syphilis
(ii) Tuberculosis
(iii) Jaundice
(iv) Japanese encephalitis
Answer:

Name of disease	Mode of transmission
i. Syphilis	Sexual contact
ii. Tuberculosis	Air
iii. Jaundice	Water
iv. Japanese encephalitis	Mosquito bite

Question 30.
Differentiate between communicable and non-communicable diseases. Give one example of each.
Answer:

Communicable Disease	Non-communicable Disease
1. Infectious disease.	1. Non-infectious disease.
2. Transferred from infected person to healthy person.	2. Not transferred through infected person.
3. Spread through agents like air, water, etc.	3. Do not spread through agents.
4. Caused by pathogens.	4. Not caused by pathogens.

Question 31.
Why do some children fall ill more frequently than others living in the same locality?
Answer:
Some children fall ill more frequently than others living in the same locality due to poor immune system. Possible reasons for poor immune system :

• Unavailability of balanced diet
• Unhygienic conditions at home
• Improper sanitation
• (Poor food consumption
• Using contaminated water

Long Answer Type Questions

Question 1.
“On exposure with an infectious microbe does not necessarily mean developing noticeable disease.” Do you agree? Explain with reason. If yes, how severe infections occur in our body?
Answer:
Yes, I agree with the statement.
The severity of disease manifestations depends on the number of microbes in the body. If the number of microbes is very small, the disease manifestations may be minor or unnoticed. But if the number of the microbes is large, the disease can be severe enough to be life-threatening.

The immune system is also a major factor that determines the number of microbes surviving in the body. The cells of immune system go into action each time infecting microbes enter the body. If they are successful, we do not actually come down with any disease and the manifestation of the disease will be minor. However, if the immune system fails, severe infections occur in the body.

Question 2.
What are the different means by which infectious diseases are spread?
Answer:
Means of spread of diseases is called Epidemiology.
Air-borne diseases:

• These diseases spread through air.
• While sneezing or coughing, the droplets released in the air is inhaled by healthy person and the infection spreads.
• Example: TB, Common cold, Pneumonia, etc.

Water-borne diseases:
These diseases spread through contaminated water.
Sexually transmirted/physical contact diseases (STDs):

• These diseases spread by sexual contact from infected partner to the healthy.
• Example: AIDS, Syphilis, Gonorrhea, etc.

Vector-borne diseases :

• Vectors are intermediate carriers of infections.
• Example: Female Anopheles mosquito is a vector for malaria parasite, plasmodium.

Question 3.
Explain giving reasons :
(I) Balanced diet is necessary for maintaining healthy body.
(II) Health of an organism depends upon the surrounding environmental conditions.
(III) Our surrounding area should be free of stagnant water.
(IV) Social harmony and good economic conditions' are necessary for good health.
Answer:
(I) Our body is made up of tiny cells which are made up of variety of organic and inorganic substances. A diet is said to be a balanced diet when it gives our body proper nutrition required to function properly.

It provides all the necessary raw materials such as carbohydrates, proteins, fats, minerals, and vitamins which are essential for proper functioning of all the body system.

(II) Good environmental conditions help ,us to prevent diseases, increase the life span and improve health standards. This implies that the surrounding environmental conditions also necessary factor for a healthy individual. As in a social environment, it is very important that the following points are maintained to keep the surrounding healthy :

• Proper removal and disposal of garbage.
• Proper disposal of sewage.
• Drinking water should be pure.
• Timely pest control to control communicable diseases.

(III) Not flowing and often foul-smelling water is known as stagnant water. This is a major environmental hazard as it can become a breeding ground for the mosquitoes that transmit various infectious water-borne diseases. So, it is required to keep our surrounding area free from stagnant water.

(IV) Social harmony and good economic conditions are also the necessary elements for good health.

Good economic conditions clearly mention that it is important for an individual to fulfill his basic needs through his own income to stay healthy. Proper earning helps in providing adequate and complete balanced diet, clean clothes and hygienic conditions.
Good social environment is important factor in maintaining good health. If people mistreat each other, they could be mentally ill and they cannot lead a healthy life.

Question 4.
What is a disease? How many types of diseases have you studied? Give examples.
Answer:
The literal meaning of the term ‘disease’ is disturbed ease or being uncomfortable. Hence, disease can be defined as the condition when any physical change has occurred due to the discomfort or impairment of body.

Disease can be further categorized as:
(i) Acute: Short term diseases. Example - Typhoid.
(ii) Chronic: Long term diseases. Example - Asthma.
(iii) Congenital: Physiological abnormalities by birth. Example: Colour blindness.
(a) Acquired: Disease that is not present at the time of birth but developed after birth. Example - AIDS
(b) Infectious: Communicable diseases caused by any parasitic organism. Example - Tuberculosis.
(c) Non-infectious: Non-communicable diseases can be genetic or due to malfunctioning of internal body organ without any infection.
Example - Cancer.

Question 5.
What do you mean by disease symptoms? Explain giving two examples.
Answer:
Internal or external evidences which determine the presence of disease is called symptoms. This is an indication which appears when the functioning of system of the body is affected due to the change. The most common symptoms observed in various diseases are :

1. Fever
2. Diarrhoea
3. Fatigue
4. Body ache
5. Severe headache/nausea
6. Cold and cough

Few examples are as follows :

• Lesions on the skin can be seen when an individual is infected with chickenpox.
• Swelling of liver and yellowing of eyes can be observed in jaundice.
• Cough is the most common symptom for lung infection.
• In case cough is sustained for long term in tuberculosis.

Question 6.
Why is immune system essential for our health?
Answer:
The defence mechanism present in our body which is responsible for fighting and destroying infecting microbes is known as immune system. Immune system is not only responsible for defending against the foreign extrinsic particles but keep our body safe too. Following are few important properties discussed:

• Immune system is a defence mechanism which fight against pathogenic microbes.
• This system plays the main role in distinguishing the acquired and inborn diseases of a body.
• Having specialised cell to kill infecting microbes and keep our body healthy.
• Vaccine also helps in acquiring immunity.
• Instant actions against highly active molecules like sneezing (dust particle), coughing (presence of smoke) are some common reactions observed in our daily life.

Question 7.
What precautions will you take to justify “prevention is better than cure”?
Answer:
Prevention is better than cure can have the following precious precautionary steps :

• Maintenance of proper sanitation.
• Hygienic environment.
• Removal of pathogenic vectors.
• Consumption of sufficient balanced diet.
• Regulating the interaction among the population in between the diseased patient (communicable/infectious) and a normal individual.
• Educating about the various diseases, cause, symptoms and prevention.
• Sharing of knowledge of proper medication, suitable tests, and treatment standard.
• Vaccination for proper immunisation.

Question 8.
Why are antibiotics not effective for viral disease?
Answer:
The term antibiotics refers to anti = against and biotic = bacteria. Antibiotics are not effective for viral disease because viruses are very simple that they use their host cells to perform their activities for them. The principle behind working action of antibiotic involves the blockage of various biochemical pathways of microorganisms and damaging the cell wall which leads to killing of cells.

Viruses have property to use host cell for their own life processes as they can operate only few biochemical cycles by themselves. Whereas bacteria are capable of performing all the different life processes without the help of host cell. This is why an antibiotic is unable to kill viruses specifically than that of bacteria.

Question 9.
Why is AIDS considered to be a ‘Syndrome’ and not a disease?
Answer:
A collection of signs and symptoms is known as syndrome. It is known to appear frequently but without a known cause. However, a disease can be stated as the condition which can harm the bodily functions in a prolonged state of syndrome. The development of HIV virus in the body transferred through either sexual mode or by blood transfusion is responsible for AIDS. It spreads into the lymph nodes damaging the immune system, of the individual. This causes the weakening of body’s barrier system and attracting several infections to encounter at once; leading to even a small gut infection to turn into severe diarrhoea with blood loss. The effect of disease becomes very severe and complex, at times killing the person suffering from AIDS. Hence, there is no specific disease symptom for AIDS but it results in a complex disease and symtoms. Therefore, it is known as syndrome.