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Chapter 8

Health and Hygiene

Class 8 - Living Science Biology Ratna Sagar


Check your Progress

Question 1

Complete the given table by filling in the blanks numbered 1 to 10.

DiseasePathogenVector
1Plasmodium2
Amoebic dysentery34
56Rat flea
Yellow fever78
9DENV10

Answer

DiseasePathogenVector
Malaria (1)PlasmodiumFemale Anopheles Mosquito (2)
Amoebic dysenteryEntamoeba (3)Housefly (4)
Plague (5)Yersinia pestis (6)Rat flea
Yellow feverYellow fever Virus (7)Aedes mosquito (8)
Dengue (9)DENVAedes mosquito (10)

Tick the most appropriate answer

Question 1

Communicable diseases are also called

  1. infectious diseases
  2. acquired diseases
  3. congenital diseases
  4. none of these

Answer

infectious diseases

Reason — The diseases which spread from infected person to healthy persons are called communicable diseases or infectious diseases.

Question 2

Which of the following is a communicable disease?

  1. malaria
  2. cancer
  3. allergy
  4. diabetes

Answer

Malaria

Reason — Malaria is spread by female anopheles mosquito.

Question 3

Which of these is not a viral disease?

  1. rabies
  2. measles
  3. filariasis
  4. dengue

Answer

filariasis

Reason — Filariasis is caused by Whuchereria bancrofti (roundworm).

Question 4

Which of these diseases spreads through contact with infected rats?

  1. dengue
  2. sleeping sickness
  3. malaria
  4. plague

Answer

plague

ReasonYersinia pestis is the causative bacteria of plague. Rat flea acts as its vector and infect rats. Infected rats when come in contact with human beings transmit it to them.

Question 5

Which of the following is a bacterial disease?

  1. malaria
  2. measles
  3. plague
  4. dengue

Answer

Plague

Reason — Plague is caused by Yersinia pestis bacteria.

Question 6

Which of the following disease is caused due to animal bite?

  1. malaria
  2. tetanus
  3. rabies
  4. tuberculosis

Answer

rabies

Reason — Rabies is a viral disease which is caused due to bite of infected dogs.

Question 7

Acquired Immuno Deficiency Syndrome could develop due to

  1. defective liver
  2. defective thymus
  3. HIV
  4. Weak immune system

Answer

HIV

Reason — Human Immuno-deficiency virus causes AIDS which leads to the break down of immune system.

Question 8

It is the process of developing immunity or resistance against a particular disease.

  1. vaccination
  2. pollination
  3. immunization
  4. fertilization

Answer

immunization

Reason — The process of making a person immune to a particular disease is called immunization.

Fill in the blanks

Question 1

............... causes ringworm in human beings.

Answer

Fungus causes ringworm in human beings.

Question 2

............... vaccine is given to children as a preventive measure against tuberculosis.

Answer

BCG vaccine is given to children as a preventive measure against tuberculosis.

Question 3

AIDS is caused by ............... virus.

Answer

AIDS is caused by Human Immuno-deficiency virus.

Question 4

The administration of a weakened pathogen to stimulate the immune system to develop resistance against that pathogen is called ............... .

Answer

The administration of a weakened pathogen to stimulate the immune system to develop resistance against that pathogen is called vaccination.

Question 5

Bites of poisonous snakes can only be treated with ............... serum.

Answer

Bites of poisonous snakes can only be treated with anti-venom serum.

Question 6

A ............... is a crack in the bone which requires immediate medical attention.

Answer

A fracture is a crack in the bone which requires immediate medical attention.

Tick mark the correctly matched pairs

Question 1

Tick mark the correctly matched pairs with regard to diseases spread by group of organisms.

  1. HIV — viral disease
  2. Ringworm — bacterial disease
  3. Malaria — protozoan disease
  4. Dengue — fungal disease
  5. Sleeping sickness — bacterial disease

Answer

The correctly matched pairs are:

HIV — viral disease

Malaria — protozoan disease

Circle the odd one

Question 1

plague, measles, dengue, yellow fever

Answer

plague

Reason — Plague is bacterial while others are viral.

Question 2

malaria, dengue, chikungunya, rabies

Answer

malaria

Reason — Malaria is protozoan disease while others are viral.

Differentiate between

Question 1

communicable and non-communicable diseases

Answer

Sl.
No.
Communicable diseasesNon-communicable diseases
1.The diseases that are passed on from an infected person to a healthy person through contact, air, water, food or other organisms are called Communicable diseases.Non-communicable diseases are the diseases that don't spread from unhealthy person to healthy person.
2.They are also called infectious diseases.They are also called non-infectious diseases.
3.For example: Measles, InfluenzaFor example: cancer, diabetes

Question 2

vaccination and immunization

Answer

Sl.
No.
VaccinationImmunization
1.Administration of a weakened or inactive pathogen (a vaccine) to stimulate the immune system to develop resistance against that pathogen is called vaccination. A vaccine can be injected or taken orally.The process by which a person is made resistant or immune against a particular disease by administering a vaccine is called immunization.
2.It is the process of administering vaccine. A vaccine may not always guarantee immunity.It is the process of making a person immune to a particular disease.

Answer the following in short

Question 1

Are good health and being free from diseases mean the same? How?

Answer

No, good health and being free from diseases do not mean the same. Health refers to a state of complete physical, mental and social well-being and not merely an absence of disease or infirmity. A healthy person is always energetic and disease-free whereas a disease-free person may not necessarily be healthy or energetic.

Question 2

Name any five communicable diseases.

Answer

Five communicable diseases are:

  1. Influenza
  2. Measles
  3. Malaria
  4. Dengue
  5. AIDS

Question 3

What are pathogens?

Answer

The disease causing microorganisms are called pathogens or germs.

Question 4

Name the virus which causes AIDS. Give the full form of AIDS.

Answer

The virus which causes AIDS is Human Immuno-deficiency Virus (HIV). The full form of AIDS is Acquired Immuno Deficiency Syndrome

Question 5

Name any two common vectors which help in the transmission of diseases.

Answer

Two common vectors which help in the transmission of diseases are:

  1. Mosquitoes
  2. Houseflies

Question 6

What kind of first aid is given to a person bitten by a poisonous snake?

Answer

Following first aid should be given to a person bitten by a poisonous snake:

  1. The patient should be kept calm as panic enhances the heartbeat rate, which circulates the venom faster in the body.
  2. All snakebites should be considered as poisonous and treated quickly.
  3. The wound should be cleaned with an antiseptic lotion. Potassium permanganate should not be used.
  4. To limit the spread of venom, bandage the bitten limb with splint and immobilize it.
  5. Do not give any food, water or alcoholic drink to the victim as it will increase his metabolic rate.
  6. Try to draw out the venom within 5 minutes of the bite.

Question 7

Name the vaccine given against tuberculosis.

Answer

The vaccine given against tuberculosis is BCG (Bacillus of Calmette-Guerin).

Question 8

What is first aid?

Answer

The immediate help given to a person before formal treatment in case of an accident or sudden illness is called first aid.

Answer the following in detail

Question 1

What is health? Differentiate between good health and being disease-free.

Answer

Health is a state of complete physical, mental and social well-being and not merely an absence of disease or infirmity. Thus, being healthy includes three spheres: physical, mental and social well being.

Following are the differences between good health and being disease-free:

Sl.
No.
Being healthyBeing disease-free
1.State of physical,mental and social well-being.State of body without having any discomfort or symptoms of a disease.
2.A healthy person is always energetic and disease-free.A disease-free person may not necessarily be healthy or energetic.

Question 2

'Prevention is better than cure'. Write about general methods of prevention of communicable disease.

Answer

Diseases can be prevented by maintaining personal and community hygiene and avoiding unhealthy habits and lifestyle. Following are the general methods of preventing communicable diseases:

  1. By preventing exposure to infectious microbes
    1. To prevent exposure to air-borne microbes, live in healthy and hygienic conditions.
    2. To prevent water-borne infections, drink clean and safe drinking water.
    3. To prevent vector-borne infections, clean your surrounding so that the disease-carrying vectors do not flourish there.
  2. By providing proper and sufficient food
    1. The functioning of the immune system is dependent upon the type of nutrients the body receives. Thus, eating proper and sufficient food is very necessary for prevention of a disease.

Question 3

Explain how does the body react after the entry of microbes in the body.

Answer

Our body has several natural defences such as skin, white blood cells and mucous to ward off infections.

  • Tears wash away germs from the eyes.
  • Mucous lining in the nasal cavity traps germs to purify inhaled air.
  • Leucocytes (WBCs) in blood attack invading germs.
  • Strong acid in stomach kill many germs in food.
  • Skin acts as a barrier and keeps out most germs.

Besides these natural defences, the body has a special system of defence known as the immune system. When a microbe enters a person's body, specific antibodies are produced in the blood to fight it. These antibodies provide natural resistance to the body against that particular microbe.

Question 4

How does excess alcohol and drugs consumption affect human beings?

Answer

Alcohol consumption — Alcoholic drinks slow down brain activity and weaken its control system when taken in large quantities. It also damages the liver by causing liver cirrhosis.

Drug addiction — Narcotics such as cocaine, heroin, marijuana and opium are harmful substances that can lead to addiction. Once a person starts consuming drugs, a condition of either physical or psychological dependence is produced. During physical dependence, the body requires a continuos supply of drug to be effective. This is called addiction. An overdose of drugs can severely depress the central nervous system with respiratory failure leading to death.

Question 5

Write the first aid for insect and snake bites.

Answer

First aid for insect bites-

  1. Keep the person calm and remove the sting with the help of tweezers. With the help of an adult, scrap the area on the skin with a blunt knife. Do not cut.
  2. Wash the area with soap and cold water. Apply oil or vaseline and cover the area with a sterile gauze.
  3. Apply ice on the area swollen due to the sting.

First aid for poisonous snake bites-

  1. The patient should be kept calm as panic enhances the heartbeat rate, which circulates the venom faster in the body.
  2. All snakebites should be considered as poisonous and treated quickly.
  3. The wound should be cleaned with an antiseptic lotion. Potassium permanganate should not be used.
  4. To limit the spread of venom, bandage the bitten limb with splint and immobilize it.
  5. Do not give any food, water or alcoholic drink to the victim as it will increase his metabolic rate.
  6. Try to draw out the venom within 5 minutes of the bite.

Name the vectors and pathogens

Question 1

Given below are the names of a few vector-borne diseases. Name the vectors for these diseases and pathogens of diseases carried by them.

malaria, dengue, yellow fever, amoebic dysentery, sleeping sickness, plague, rabies

Answer

DiseaseVectorPathogen
MalariaFemale Anopheles mosquitoPlasmodium (protozoan)
DengueAedes mosquitoDENV (virus)
Yellow feverAedes mosquitoYellow fever virus
Amoebic dysenteryHouseflyEntamoeba histolytica (protozoan)
Sleeping sicknessTse-tse flyTrypanosoma (protozoan)
PlagueRat fleaYersinia pestis (bacteria)
RabiesSaliva of infected animals (dogs)Rhabdovirus (virus)

Fill blanks & answer questions

Question 1

Fill in the blanks numbered 1-6 in the following table and then answer the questions that follow.

DiseaseType of pathogenCaused by
Sleeping sickness1Caused by Trypanosoma
2VirusSpread through the bite of the mosquito Aedes aegypti
AIDS34
Amoebic dysentery56
  1. Which of the above diseases can be controlled by mosquito control?
  2. In which of the above diseases does body lose its power to fight against diseases?

Answer

DiseaseType of pathogenCaused by
Sleeping sicknessProtozoan (1)Caused by Trypanosoma
Dengue (2)VirusSpread through the bite of the mosquito Aedes aegypti
AIDSVirus (3)Caused by HIV virus that spreads through sexual contact, blood transfusion, etc. (4)
Amoebic dysenteryProtozoan (5)Caused by Entamoeba and spreads through food contaminated by housefly (6)
  1. Dengue can be controlled by mosquito control.
  2. In AIDS, body loses its power to fight against diseases.

Fill blanks using keywords

Question 1

Use the key words given below to fill in the blanks in the following paragraph.

communicable, malaria, microorganisms, air-borne, germs, viral, protozoan, Anopheles, dog

Organisms which cannot be seen with naked eyes are called ............... Disease-causing microorganisms are called ............... Because of small size, the viruses can easily be transmitted from one person to another through a sneeze as an ............... infection. Plasmodium is a ............... which causes ............... and is transmitted by female ............... mosquito. Rabies is a ...............disease which is spread by the bite of a ............... All the diseases which are caused by the microorganisms are called ............... diseases.

Answer

Organisms which cannot be seen with naked eyes are called microorganisms. Disease-causing microorganisms are called germs. Because of small size, the viruses can easily be transmitted from one person to another through a sneeze as an air-borne infection. Plasmodium is a protozoan which causes malaria and is transmitted by female Anopheles mosquito. Rabies is a viral disease which is spread by the bite of a dog. All the diseases which are caused by the microorganisms are called communicable diseases.

Think and answer

Question 1

It has been diagnosed that the body of a patient has lost the capacity to fight any infection. Name the disease he is suffering from. Which type of microbe is responsible for this disease? How could it have been prevented.

Answer

The disease he is suffering from is AIDS. This disease is viral disease caused by Human Immuno-deficiency virus. AIDS could have been prevented by:

  1. Screening of blood before transfusion.
  2. Avoiding sharing and reuse of blades, needles and syringes and surgical instruments.
  3. Avoiding pregnancy if mother is HIV positive.
  4. Safe sex.
  5. Educating people.

Question 2

At a rural health centre, a nursing mother is given an immunization schedule for BCG and DPT to be given to her baby. What are the diseases against which the child will be protected?

Answer

The child will be protected against Tuberculosis by BCG vaccine. He will be protected against Diphtheria, Pertussis (whooping cough) and Tetanus by DPT vaccine.

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