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Solutions for Biology, Class 8, ICSE
What is health? Differentiate between good health and being disease-free.
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 healthy | Being 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. |
'Prevention is better than cure'. Write about general methods of prevention of communicable disease.
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:
Explain how does the body react after the entry of microbes in the body.
Our body has several natural defences such as skin, white blood cells and mucous to ward off infections.
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.
How does excess alcohol and drugs consumption affect human beings?
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.
Write the first aid for insect and snake bites.
First aid for insect bites-
First aid for poisonous snake bites-
Are good health and being free from diseases mean the same? How?
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.
Name any five communicable diseases.
Five communicable diseases are:
What are pathogens?
The disease causing microorganisms are called pathogens or germs.
Name the virus which causes AIDS. Give the full form of AIDS.
The virus which causes AIDS is Human Immuno-deficiency Virus (HIV). The full form of AIDS is Acquired Immuno Deficiency Syndrome
Name any two common vectors which help in the transmission of diseases.
Two common vectors which help in the transmission of diseases are:
What kind of first aid is given to a person bitten by a poisonous snake?
Following first aid should be given to a person bitten by a poisonous snake:
Name the vaccine given against tuberculosis.
The vaccine given against tuberculosis is BCG (Bacillus of Calmette-Guerin).
What is first aid?
The immediate help given to a person before formal treatment in case of an accident or sudden illness is called first aid.
Complete the given table by filling in the blanks numbered 1 to 10.
Disease | Pathogen | Vector |
---|---|---|
1 | Plasmodium | 2 |
Amoebic dysentery | 3 | 4 |
5 | 6 | Rat flea |
Yellow fever | 7 | 8 |
9 | DENV | 10 |
Disease | Pathogen | Vector |
---|---|---|
Malaria (1) | Plasmodium | Female Anopheles Mosquito (2) |
Amoebic dysentery | Entamoeba (3) | Housefly (4) |
Plague (5) | Yersinia pestis (6) | Rat flea |
Yellow fever | Yellow fever Virus (7) | Aedes mosquito (8) |
Dengue (9) | DENV | Aedes mosquito (10) |
plague, measles, dengue, yellow fever
plague
Reason — Plague is bacterial while others are viral.
malaria, dengue, chikungunya, rabies
malaria
Reason — Malaria is protozoan disease while others are viral.
communicable and non-communicable diseases
Sl. No. | Communicable diseases | Non-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, Influenza | For example: cancer, diabetes |
vaccination and immunization
Sl. No. | Vaccination | Immunization |
---|---|---|
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. |
Fill in the blanks numbered 1-6 in the following table and then answer the questions that follow.
Disease | Type of pathogen | Caused by |
---|---|---|
Sleeping sickness | 1 | Caused by Trypanosoma |
2 | Virus | Spread through the bite of the mosquito Aedes aegypti |
AIDS | 3 | 4 |
Amoebic dysentery | 5 | 6 |
Disease | Type of pathogen | Caused by |
---|---|---|
Sleeping sickness | Protozoan (1) | Caused by Trypanosoma |
Dengue (2) | Virus | Spread through the bite of the mosquito Aedes aegypti |
AIDS | Virus (3) | Caused by HIV virus that spreads through sexual contact, blood transfusion, etc. (4) |
Amoebic dysentery | Protozoan (5) | Caused by Entamoeba and spreads through food contaminated by housefly (6) |
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.
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.
............... causes ringworm in human beings.
Fungus causes ringworm in human beings.
............... vaccine is given to children as a preventive measure against tuberculosis.
BCG vaccine is given to children as a preventive measure against tuberculosis.
AIDS is caused by ............... virus.
AIDS is caused by Human Immuno-deficiency virus.
The administration of a weakened pathogen to stimulate the immune system to develop resistance against that pathogen is called ............... .
The administration of a weakened pathogen to stimulate the immune system to develop resistance against that pathogen is called vaccination.
Bites of poisonous snakes can only be treated with ............... serum.
Bites of poisonous snakes can only be treated with anti-venom serum.
A ............... is a crack in the bone which requires immediate medical attention.
A fracture is a crack in the bone which requires immediate medical attention.
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 |
---|
Disease | Vector | Pathogen |
---|---|---|
Malaria | Female Anopheles mosquito | Plasmodium (protozoan) |
Dengue | Aedes mosquito | DENV (virus) |
Yellow fever | Aedes mosquito | Yellow fever virus |
Amoebic dysentery | Housefly | Entamoeba histolytica (protozoan) |
Sleeping sickness | Tse-tse fly | Trypanosoma (protozoan) |
Plague | Rat flea | Yersinia pestis (bacteria) |
Rabies | Saliva of infected animals (dogs) | Rhabdovirus (virus) |
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.
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:
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?
The child will be protected against Tuberculosis by BCG vaccine. He will be protected against Diphtheria, Pertussis (whooping cough) and Tetanus by DPT vaccine.
Tick mark the correctly matched pairs with regard to diseases spread by group of organisms.
The correctly matched pairs are:
HIV — viral disease
Malaria — protozoan disease
Communicable diseases are also called
infectious diseases
Reason — The diseases which spread from infected person to healthy persons are called communicable diseases or infectious diseases.
Which of the following is a communicable disease?
Malaria
Reason — Malaria is spread by female anopheles mosquito.
Which of these is not a viral disease?
filariasis
Reason — Filariasis is caused by Whuchereria bancrofti (roundworm).
Which of these diseases spreads through contact with infected rats?
plague
Reason — Yersinia 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.
Which of the following is a bacterial disease?
Plague
Reason — Plague is caused by Yersinia pestis bacteria.
Which of the following disease is caused due to animal bite?
rabies
Reason — Rabies is a viral disease which is caused due to bite of infected dogs.
Acquired Immuno Deficiency Syndrome could develop due to
HIV
Reason — Human Immuno-deficiency virus causes AIDS which leads to the break down of immune system.
It is the process of developing immunity or resistance against a particular disease.
immunization
Reason — The process of making a person immune to a particular disease is called immunization.