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Why Do We Fall Ill

Class 9th Science NCERT Exemplar Solution
Multiple Choice Questions
  1. Which one of the following is not a viral disease?A. Dengue B. AIDS C. Typhoid D.…
  2. Which one of the following is not a bacterial disease?A. Cholera B. Tuberculosis C.…
  3. Which one of the following disease is not transmitted by mosquito?A. Brain fever B.…
  4. Which one of the following disease is caused by bacteria?A. Typhoid B. Anthracis C.…
  5. Which one of the following diseases is caused by protozoans?A. Malaria B. Influenza C.…
  6. Which one of the following has a long-term effect on the health of an individual?A. Common…
  7. Which of the following can make you ill if you come in contact with an infected person?A.…
  8. AIDS cannot be transmitted byA. sexual contact B. hugs C. breastfeeding D. blood…
  9. Making antiviral drugs is more difficult than making anti-bacterial medicines becauseA.…
  10. Which one of the following causes kala azar?A. Ascaris B. Trypanosoma C. Leishmania D.…
  11. If you live in an overcrowded and poorly ventilated house, it is possible that you may…
  12. Which disease is not transmitted by mosquitoes?A. Dengue B. Malaria C. Brain fever or…
  13. Which one of the following is not important for individual health?A. Living in clean space…
  14. Choose the wrong statementA. High blood pressure is caused by excessive weight and lack of…
  15. We should not allow mosquitoes to breed in our surroundings because theyA. multiply very…
  16. You are aware of Polio Eradication Programme in your city. Children are vaccinated…
  17. Viruses, which cause hepatitis, are transmitted throughA. air B. water C. food D. personal…
  18. Vectors can be defined asA. animals carry the infecting agents from sick person to another…
Short Answer Type
  1. Give two examples for each of the following (a) Acute diseases (b) Chronic diseases (c)…
  2. Name two diseases caused by Protozoans What are their causal organisms?…
  3. Which bacterium causes peptic ulcers? Who discovered the above pathogen for the first…
  4. What is an antibiotic? Give two examples
  5. (a) Pneumonia is an example of _______ disease. (b) Many skin diseases are caused…
  6. Name the target organs for the following diseases (a) Hepatitis targets______. (b) Fits or…
  7. Who discovered vaccine for the first time? Name two diseases which can be prevented by…
  8. (a) _____ disease continues for many days and causes______ on body. (b) _____disease…
  9. Classify the following diseases as infectious or noninfectious.
  10. Name any two groups of microorganisms from which antibiotics could be extracted.…
  11. Name any three diseases transmitted through vectors.
Long Answer Type
  1. Explain giving reasons (a) Balanced diet is necessary for maintaining healthy body. (b)…
  2. What is a disease? How many types of diseases have you studied? Give examples.…
  3. What do you mean by disease symptoms? Explain giving two examples?…
  4. Why is immune system essential for our health?
  5. What precautions will you take to justify prevention is better than cure.…
  6. Why do some children fall ill more frequently than others living in the same locality?…
  7. Why are antibiotics not effective for viral disease?
  8. Becoming exposed to or infected with an infectious microbe does not necessarily mean…
  9. Give any four factors necessary for a healthy person.
  10. Why is AIDS considered to be a Syndrome and not a disease?

Multiple Choice Questions
Question 1.

Which one of the following is not a viral disease?
A. Dengue

B. AIDS

C. Typhoid

D. Influenza


Answer:

Typhoid fever is not a viral disease because it is an acute illness. In typhoid, the bacteria are deposited in water medium or food medium by a human carrier and can be easily spread into others.


Question 2.

Which one of the following is not a bacterial disease?
A. Cholera

B. Tuberculosis

C. Anthrax

D. Influenza


Answer:

Influenza is not a bacterial disease but it is a contagious disease. Contagious disease is one in which the disease spreads due to direct contact or touch. It is caused by flu viruses.


Question 3.

Which one of the following disease is not transmitted by mosquito?
A. Brain fever

B. Malaria

C. Typhoid

D. Dengue


Answer:

Typhoid is spread by eating or drinking the contaminated food or water of the person infected by the disease.


Question 4.

Which one of the following disease is caused by bacteria?
A. Typhoid

B. Anthracis

C. Tuberculosis

D. Malaria


Answer:

Malaria is caused by a single celled parasite called Plasmodium.

Malaria is caused by the Plasmodium parasite. The parasite can be spread to humans through the bites of infected mosquitoes in their blood.


Question 5.

Which one of the following diseases is caused by protozoans?
A. Malaria

B. Influenza

C. AIDS

D. Cholera


Answer:

Malaria is caused by the protozoan parasite Plasmodium. Human malaria is caused by four different species of Plasmodium: P. falciparum, P. malariae, P. ovale and P. vivax.


Question 6.

Which one of the following has a long-term effect on the health of an individual?
A. Common cold

B. Chicken pox

C. Chewing tobacco

D. Stress


Answer:

Tobacco use leads most commonly to diseases affecting the heart, liver and lungs.


Question 7.

Which 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:

If we come in contact with an infected person, then then the germs are easily spread from one person to another by simple ways such as: sneezing, talking etc. Because germs can be easily transferred from one person to another by direct contact.


Question 8.

AIDS cannot be transmitted by
A. sexual contact

B. hugs

C. breastfeeding

D. blood transfusion


Answer:

HIV is passed on from person to person if infected body fluids (such as blood, is transmitted, sexual contact is made or when child is in mother’s womb. HIV does not spread from touching someone, hugging them or shaking their hand.


Question 9.

Making antiviral drugs is more difficult than making anti-bacterial medicines because
A. viruses make use of host machinery

B. viruses are on the borderline of living and non-living

C. viruses have very few biochemical mechanisms of their own

D. viruses have a protein coat


Answer:

Manufacturing safe and effective antiviral drugs is difficult, because viruses use the host's cells to replicate and live within them. This makes it difficult to find targets for the drug that would interfere with the virus without also harming the host organism's cells.


Question 10.

Which one of the following causes kala azar?
A. Ascaris

B. Trypanosoma

C. Leishmania

D. Bacteria


Answer:

Kala-azar is caused by a protozoan parasite called: Leishmania. The other name for Kala azar is Black fever or Dumdum fever.


Question 11.

If you live in an overcrowded 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:

An airborne disease is any disease that is caused by pathogens and transmitted through the air especially in those area that have poor ventilation or no ventilation at all.


Question 12.

Which disease is not transmitted by mosquitoes?
A. Dengue

B. Malaria

C. Brain fever or encephalitis

D. Pneumonia


Answer:

Pneumonia is caused by the bacteria-like Mycoplasma pneumoniae.


Question 13.

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:

Health comes from healthy habits. Healthy habits like eating regular fresh meals, personal and social hygiene, adequate rest and sleep with exercise leads to balanced state of health and mind.


Question 14.

Choose the wrong statement
A. High blood pressure is caused by excessive weight and lack of exercise.

B. Cancers can be caused by genetic abnormalities

C. Peptic ulcers are caused by eating acidic food

D. Acne in not caused by staphylococci


Answer:

Peptic ulcers develop in the lining of the stomach or the small intestine. It is usually a result of inflammation caused by the bacteria called as H. pylori.


Question 15.

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:

Mosquitoes are the disease carriers. The diseases caused by mosquitos include malaria, dengue fever, yellow fever etc.


Question 16.

You are aware of Polio Eradication Programme in your city. Children are vaccinated because
A. vaccination kills the polio causing microorganisms

B. prevents the entry of polio causing organism

C. it creates immunity in the body

D. all the above


Answer:

Younger the child, higher is the risk of getting the polio disease. So, they are immunized to fight against the disease by getting immunized.


Question 17.

Viruses, which cause hepatitis, are transmitted through
A. air

B. water

C. food

D. personal contact


Answer:

If the feces of any infected person contaminates the water bodies, then there is a huge potential for Hepatitis A virus to spread. These viruses can be spread from the various water resources.


Question 18.

Vectors can be defined as
A. animals carry the infecting agents from sick person to another healthy person

B. micro-organisms which cause many diseases

C. infected person

D. diseased plants


Answer:

A disease vector is any agent (animal, or microorganism) that carries and spreads diseases. It can be as small as a housefly.



Short Answer Type
Question 1.

Give two examples for each of the following

(a) Acute diseases

(b) Chronic diseases

(c) Infectious diseases

(d) Non-infectious diseases


Answer:

(a) Viral fever, Flu

A disease or disorder that lasts a short time, comes on rapidly, and is accompanied by distinct symptoms. Example is Viral fever and Flu.


(b) Elephantiasis, Tuberculosis (TB)


A disease that lasts for more a time-period of more than 3 months then, it is called chronic disease. Generally, cannot be prevented by vaccines or cured by medication, nor do they just disappear.


(c) Small pox, Chicken pox


Infectious diseases are caused by pathogenic microorganisms, such as bacteria, viruses, parasites or fungi; the diseases can be spread, directly or indirectly, from one person to another.


(d) Diabetes, Goitre


A disease that is not contagious is called a non-infectious disease. These diseases are not caused by pathogens. Instead, they are likely to have causes such as lifestyle factors, environmental toxins, or gene mutations within an individual.



Question 2.

Name two diseases caused by Protozoans What are their causal organisms?


Answer:

The two diseases caused by Protozoans are:

1) Sleeping sickness caused by Trypanosoma:


The medical name for sleeping sickness is African Trypanosomiasis. And, it is caused by the protozoa which belongs to the species, Trypanosoma brucei.


2) Kala-azar caused by Leishmania:


The medical name for Kala Azar is Visceral leishmaniasis. It is caused by the protozoa of the Leishmania genus.



Question 3.

Which bacterium causes peptic ulcers? Who discovered the above pathogen for the first time?


Answer:

The bacterium that causes peptic ulcers is: Helicobacter pylori.

The scientists Marshall and Warren discovered this bacterium is the year 1982 after they diagnosed that these germs caused the stomach ulcers*.


*Ulcer: It is an open sore in the internal surface of the body caused by the breaking of the skin.



Question 4.

What is an antibiotic? Give two examples


Answer:

Antibiotic is a type of medicine that inhibits the growth of bacteria. Some of the antibiotics contain anti-protozoal activity. Examples, Penicillin and Streptomycin.



Question 5.

Fill in the blanks

(a) Pneumonia is an example of _______ disease.

(b) Many skin diseases are caused by_______.

(c) Antibiotics commonly block biochemical pathways important for the growth of _______.

(d) Living organisms carrying the infecting agents from one person to another are called _______.


Answer:

(a) Communicable.

Pneumonia is a communicable disease, which means it can be spread from one person to another and is also an infectious disease of lungs.


(b) Fungi


Jock itch, also called tinea cruris, is a common skin infection that is caused by a type of fungus called tinea. This type of fungal disease is accelerated in sultry, warm or humid areas.


(c) Bacteria


An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein produced in the body. Using this binding mechanism, an antibody can tag a microbe or an infected cell for attack by other parts of the immune system, or can neutralize the foreign bacterial infection or attack.


(d) Vector


vector means that it carries a disease from one host to another.



Question 6.

Name the target organs for the following diseases

(a) Hepatitis targets______.

(b) Fits or unconsciousness targets _______.

(c) Pneumoniae targets ______.

(d) Fungal disease targets ______.


Answer:

(a) Liver

Hepatitis causes scarring of the liver (cirrhosis). As the disease progresses, symptoms such as skin problems, blood disorders, and fever may appear. In the long term, hepatitis C can lead to severe liver damage and is fatal.


(b) Brain


A seizure, also known as a fit, is caused by a disturbance in the electrical activity of the brain, which can be due to conditions such as epilepsy.


(c) Lungs


Pneumonia is an infection in one or both lung. It can be caused by fungi, bacteria, or viruses. Pneumonia causes inflammation in your lung's air sacs, or alveoli. The alveoli fill with fluid or pus, making it difficult to breathe. It is also fatal.


(d) Skin


The fungi that attack the skin or its appendages (nail, feathers and hair). Some examples of these infection include ringworms, jock-itch and athlete's foot. These fungi are known as dermatophytes.



Question 7.

Who discovered ‘vaccine’ for the first time? Name two diseases which can be prevented by using vaccines.


Answer:

In the year 1796, Sir Edward Jenner carried out an experiment on an eight-year-old boy named James Phipps. Sir Edward took fluid from a cowpox blister and rubbed it on the skin of the boy and the boy recovered. In 1798, the results were finally published and Jenner coined the word vaccine from the Latin 'vacca' for cow.

Smallpox and Polio are the two diseases that can be prevented using vaccines.


The Smallpox vaccine was the first successful vaccine which was developed by Edward Jenner in 1796..



Question 8.

Fill in the blanks

(a) _____ disease continues for many days and causes______ on body.

(b) _____disease continues for a few days and causes no longer 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

A chronic condition is a human health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. Examples are Asthma, Cancer and Diabetes etc.


(b) Acute


Acute diseases tend to have very quick onsets and typically last for only a brief period. Example is Asthma, Appendicitis and Hepatitis etc


(c) Health


Health is the level of functional and metabolic efficiency of a living organism.


(d) Infectious/communicable


Common cold, also known simply as a cold, is a viral infectious disease of the upper respiratory tract that primarily affects the nose.


(e) Fungi


One of the skin infection or disease caused by Fungi is Ringworm that causes a red, circular, itchy rash. Ringworm is officially known as tinea or dermatophytosis.



Question 9.

Classify the following diseases as infectious or noninfectious.


Answer:

(a) AIDS - Infectious

(b) Tuberculosis - Infectious


(c) Cholera - Infectious


(d) High blood pressure – No- Infectious


(e) Heart disease – Non-Infectious


(f) Pneumonia - Infectious


(g) Cancer – Non-Infectious


Infectious disease is caused by a pathogen that enters the body and can be transferred from person to person. Non-infectious disease is not caused by a pathogen or organism carrying disease.



Question 10.

Name any two groups of microorganisms from which antibiotics could be extracted.


Answer:

Bacteria and Fungi

Antibodies is a substance produced by certain bacteria or fungi that kills other cells or interferes with their growth. In nature, these substances help some microbes survive by limiting the multiplication of other microbes that share the same environment. Antibiotics that attack pathogenic (disease-causing) microbes without severely harming normal body cells are useful as drugs.



Question 11.

Name any three diseases transmitted through vectors.


Answer:

Malaria, Dengue and Kala Azar

Vector-borne diseases are illnesses that are transmitted by vectors, which include mosquitoes, ticks, and fleas. These vectors can carry infective pathogens such as viruses, bacteria, and protozoa, which can be transferred from one host (carrier) to another.




Long Answer Type
Question 1.

Explain giving reasons

(a) Balanced diet is necessary for maintaining healthy body.

(b) Health of an organism depends upon the surrounding environmental conditions.

(c) Our surrounding area should be free of stagnant water.

(d) Social harmony and good economic conditions are necessary for good health.


Answer:

(a) Food is necessary for the growth and development of the body. Balanced diet provides raw materials and energy in appropriate amount needed for the substances likes protein, carbohydrates, fats, minerals etc which in turn are essential for the proper growth and functioning of the healthy body.


(b) Health is a state of being well enough to function well physically, mentally and socially and these conditions depend upon the surrounding environmental conditions. eg., If there is unhygienic conditions in surrounding area, it is likely we might get infected or diseased with infectious, chronic or deadly diseases.


(c) This is so because many water borne diseases and insect vectors flourish in stagnant water which cause diseases in human beings.


(d) Human beings live in societies and different localities like villages or cities, which determines the social and physical environment and hence both are to be kept in harmony. Public cleanliness is important for individual health. For better living conditions lot of money is required. We need good food for healthy body and for this we have to earn more. For the treatment of diseases also, one has to be in good economic condition.



Question 2.

What is a disease? How many types of diseases have you studied? Give examples.


Answer:

When the functioning or the appearance of one or more systems of the body change for the worse the body is said to be diseased. The diseases can be —acute/chronic/ infectious/non-infectious. Examples, influenza, tuberculosis, pneumonia, cancer respectively.



Question 3.

What do you mean by disease symptoms? Explain giving two examples?


Answer:

When the functioning or the appearance of one or more systems of the body will change for the worse, it gives certain abnormal signs of the disease. These visual changes in human beings are called symptoms. Symptoms give indication of the presence of a particular disease.

(i) Lesions on the skin are the symptoms of chickenpox. Example


(ii) Cough is the symptom of lung infection.



Question 4.

Why is immune system essential for our health?


Answer:

The immune system of our body is a kind of defense mechanism to fight against pathogenic microbes. It has cells that are specialized to kill infecting microbes and keep our body healthy.



Question 5.

What precautions will you take to justify “prevention is better than cure”.


Answer:

The following precautions should be taken for prevention of disease:

(1) Maintaining the proper hygiene conditions.


(2) Proper awareness of the diseases.


(3) Proper knowledge about the balanced diet.


(4) Regular medical check-up.



Question 6.

Why do some children fall ill more frequently than others living in the same locality?


Answer:

The people fall ill due to poor immune system. If proper balanced diet and proper nutrition for healthy body is required to have a strong immune system.



Question 7.

Why are antibiotics not effective for viral disease?


Answer:

Antibiotics generally block the biosynthetic pathways and they block these pathways of the microbes/bacteria. However, viruses have very few biochemical mechanisms of their own and hence are unaffected by antibiotics.



Question 8.

Becoming exposed to or infected with an infectious microbe does not necessarily mean developing noticeable disease. Explain.


Answer:

Because of strong immune system our body is normally fighting off microbes. We have cells which are specialised to kill the pathogenic microbes. These cells are active when infecting microbes enter the body and if they are successful in removing the pathogen, we remain disease free. So even if we are exposed to infectious microbes, it is not necessary that we suffer from diseases.



Question 9.

Give any four factors necessary for a healthy person.


Answer:

For a healthy person it is necessary that

(i) The surrounding environment should be clean. Air and water borne diseases will not spread.


(ii) Personal hygiene prevents infectious diseases.


(iii) Proper, sufficient nourishment and food is necessary for good immune system of our body.


(iv) Immunisation against severe diseases.



Question 10.

Why is AIDS considered to be a ‘Syndrome’ and not a disease?


Answer:

AIDS causing virus— HIV that comes into the body via, the sexual organs or any other means like blood transfusion will spread to lymph nodes all over the body. The virus damages the immune system of the body and due to this the body can no longer fight off many minor infections. Instead, every small cold can become pneumonia, or minor gut infection can become 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 symptoms for AIDS but it results in a complex diseases and symptoms. Therefore, it is known as a syndrome.