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Chapter 8

Diseases and First Aid

Class 8 - Concise Biology Selina


Multiple Choice Questions

Question 1

A mosquito is a vector for :

  1. Typhoid
  2. Cholera
  3. Malaria
  4. Jaundice

Answer

Malaria

Reason — Malaria is caused by Plasmodium protozoan that is transmitted by the bite of a female Anopheles mosquito.

Question 2

Dengue is caused by a

  1. Protozoan
  2. Virus
  3. Worm
  4. Fungus

Answer

Virus

Reason — Dengue is a mosquito-borne disease caused by the dengue virus.

Question 3

The idea of vaccination was conceived by

  1. Charles Darwin
  2. Alexander Flemming
  3. Issac Newton
  4. Edward Jenner

Answer

Edward Jenner

Reason — The idea of vaccination was conceived by Edward Jenner (1749 - 1823).

Question 4

Which one of the following is not a psychotropic drug?

  1. Morphine
  2. Cocaine
  3. Heroin
  4. Penicillin

Answer

Penicillin

Reason — Morphine, Cocaine, and Heroin are psychotropic drug. But, Penicillin is an antibiotic.

Question 5

Which one of the following is a communicable disease?

  1. Measles
  2. Cancer
  3. Heart attack
  4. Allergy

Answer

Measles

Reason — Cancer, heart attack, and allergy are non-communicable diseases whereas measles is a communicable disease.

Short Answer Questions

Question 1(a)

What is a non-communicable disease ?

Answer

Non communicable diseases are those which are not caused by any germ, therefore these diseases cannot spread from an infected person to a healthy person (i.e., they are non transmissible). These may be caused due to improper functioning of the body organs. Example : diabetes, heart attack, etc.

Question 1(b)

What are communicable diseases ?

Answer

Communicable diseases are those diseases which spread from an infected person to a healthy person by the entry of microorganisms or pathogens. These diseases are caused by the germs known as pathogens. Example: Chicken pox, Malaria, Typhoid, etc.

Question 1(c)

How can we control spreading of diseases by mosquitoes and houseflies ?

Answer

We can control the spreading of diseases by mosquitoes and houseflies by using repellants, throwing garbage in covered bins, avoid stagnation of water and checking breeding of insects.

Question 1(d)

Public hygiene is equally important as personal hygiene. Give reasons.

Answer

Public hygiene involves proper disposal of human excreta and domestic wastes. It is equally important as personal hygiene for the following reasons:

  1. Sewage should be chemically treated first before being released into the water bodies to avoid water-borne diseases. There should be proper sewage lines connected to sewage treatment plants.
  2. A healthy environment should be maintained by disposing garbage in covered bins to prevent breeding of flies, avoiding stagnation of water to prevent breeding of mosquitoes.
  3. Contamination of drinking water with faeces (animal or human excreta) should be prevented as it is a major cause of diseases.

Question 2

Name the following:

(a) A viral disease caused due to sexual contact with an infected person ...............

(b) A disease caused due to Plasmodium ...............

(c) A disease caused by the bite of female Anopheles mosquito ...............

(d) Two viral diseases caused by mosquito bites ...............

(e) Any droplet-borne disease ...............

Answer

(a) AIDS

(b) Malaria

(c) Malaria

(d) Dengue fever, Chikungunya

(e) Tuberculosis

Question 3

Write short notes (2-3 sentences) on the following :

(a) Disease

(b) Immunisation

(c) Pathogen

(d) AIDS

(e) Vaccination

(f) Vector

Answer

(a) Disease — Disease is a departure from normal health through structural or functional disorder of the body. There are two major categories of diseases — Communicable or infectious diseases and Non-Communicable or non-infectious diseases.

(b) Immunization — Immunization is an artificial way of achieving protection from infections by the introduction of dead or weakened germs into one's body. Immunization is a process by which the body of an individual is made resistant to a specific disease by vaccination.

(c) Pathogen — Communicable diseases are caused due to microorganisms such as viruses, bacteria, fungi, worms and protozoa. The disease causing germs are called pathogens. Pathogens spread from one person to other through air, water, food, physical contact, cuts, sexual contact and from insects like mosquitoes, flies, etc.

(d) AIDS — AIDS stands for Acquired Immuno Deficiency Syndrome. It is caused by the HIV virus. It weakens the immunity or self defence mechanism of the human body. AIDS makes the infected person prone to many other infectious diseases. It spreads through sexual contact, blood transfusion and infected syringes.

(e) Vaccination — Vaccination is the practice of artificially introducing germs or germ substances into the body for developing resistance to particular diseases. The material introduced into the body is called the vaccine. When exposed to vaccines, the body makes antibodies and more or less permanent protection from infection is achieved.

(f) Vector — Vectors are those organisms (eg. house flies, mosquitoes, etc.) which carry germs from a source of infection but themselves do not get the infection. For example, mosquitoes while feeding on the blood of a malaria patient, gain the germs in their bodies, and get them transferred in the blood stream of a healthy person whom they bite next.

Long Answer Questions

Question 1

What is Vaccination? Mention the four ways in which vaccines are prepared, giving the name of one disease for which each type of vaccine is used.

Answer

Vaccination is the practice of artificially introducing germs or germ substances into the body for developing resistance to particular diseases. The material introduced into the body is called the vaccine. Usually, the vaccine is introduced into the body by injection and sometimes orally.
A vaccine can be prepared by any one of the following four methods —

  1. Using killed germs — e.g. TAB vaccine for typhoid.
  2. Using living weakened germs — e.g. the vaccine for measles.
  3. Using fully virulent living germs — e.g. the vaccine for smallpox.
  4. Using Toxoids — e.g. the vaccines used for diphtheria and tetanus.

Question 2

Burns can be superficial burns, deep burns or chemical burns. What emergency care would you suggest in each case.

Answer

First aid for burns depends on the degree of burns.
In the case of superficial burns, pour cold water over the burnt area. Then dry that portion and cover with sterile dressing.
In the case of deep burns, never use water, and cover the injured part with dressing.
In the case of chemical burns, wash with running water for 10 minutes and then cover with dressing.

Question 3

Describe four ways in which communicable diseases are transmitted through various indirect methods.

Answer

Indirect methods of transmission of communicable diseases are —

  1. Vectors — Vectors are those organisms (eg. house flies, mosquitoes, etc.) which carry germs from a source of infection but themselves do not get the infection. For example, mosquitoes while feeding on the blood of a malaria patient, gain the germs in their bodies, and get them transferred in the blood stream of a healthy person whom they bite next.
  2. Droplet infection — Many viral and bacterial diseases of the respiratory tract are transmitted through droplets. For example, the germs of Tuberculosis pass into the air during sneezing or coughing of the patient. These fine droplets remain suspended in the air for quite sometime. The healthy person gets the infection by inhaling the same air containing these suspended droplets. Tuberculosis, common cold, measles, diphtheria, etc. spread in this way.
  3. Contaminated food and water or drink — Many intestinal diseases are spread by the intake of vegetables and fruits that are not washed properly or are washed with contaminated water. The germs on the infected vegetables and fruits reach our alimentary canal, multiply and cause the disease.
  4. Touching and sharing items used by the infected person — The use of the same towel, handkerchief or same bed, or sharing the same utensils which were handled by the patient may spread the disease to a healthy person.
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