Living Science Biology Class 8 ICSE Solutions Chapter 4 Health and Hygiene

ICSE Living Science Biology for Class 8 Solutions Chapter 4 Health and Hygiene

Check Your Progress 1

Fill in the blanks :

Question 1.
Diseases which are present right from the birth are called ……………….
Answer:
Diseases which are present right from the birth are called acquired diseases.

Question 2.
………… and ………… are some diseases caused by parasitic worms.
Answer:
Elephantiasis and ascariases are some diseases caused by parasitic worms.

Question 3.
…………. foot is a fungal disease that spreads by direct contact.
Answer:
Athlete’s foot is a fungal disease that spreads by direct contact.

Question 4.
Malaria is caused by a protozoan called
Answer:
Malaria is caused by a protozoan called plasmodium.

Question 5.
African sleeping sickness spreads by …………… fly.
Answer:
African sleeping sickness spreads by tse-tse fly.

Question 6.
Dengue is a disease that spreads by the bite of ………… mosquito.
Answer:
Dengue is, a disease that spreads by the bite of Aedes mosquito.

Question 7.
………….is a dreadful viral disease transmitted to human by the bite of a dog.
Answer:
Rabies is a dreadful viral disease transmitted human by the bite of a dog.

Check Your Progress 2

Write True or False.

Question 1.
Lack of any nutrient in the diet is known as balanced diet.
Answer:
False. The diet containing all nutrients in right quantity according to the body requirement is known as balanced diet.

Question 2.
When the diet is deficient in proteins as well as carbohydrates, the child suffers from marasmus.
Answer:
True

Question 3.
Osteoarthritis is an uncontrolled growth of cells in body tissues.
Answer:
False. Cancer is an uncontrolled growth of cells in body tissues.

Question 4.
Liver cirrhosis is a common disease caused in persons who have been using alcohol for a long¬term.
Answer:
True

Question 5.
Bruises are injuries to tissues under the skin.
Answer:
True

A. Tick the most appropriate answer.

Question 1.
Which of the following is a congenital disease ?
a. Cholera
b. Tuberculosis
c. Beriberi
d. Sickle-cell anaemia
Answer:
d. Sickle-cell anaemia

Question 2.
Which of the following is a communicable disease ?
a. Typhoid
b. Cancer
c. Allergy
d. Diabetes
Answer:
a. Typhoid

Question 3.
Which of these is not a viral disease ?
a. Conjunctivitis
b. Measles
c. Tuberculosis
d. Polio
Answer:
c. Tuberculosis

Question 4.
Which of these is a fungal disease ?
a. Ringworm
b. Mumps
c. Hepatitis
d. Rabies
Answer:
a. Ringworm

Question 5.
Cholera is caused by
a. fungus
b. virus
c. bacterium
d. protozoan
Answer:
c. bacterium

Question 6.
Typhoid spreads through
a. air
b. insect bite
c. canned food
d. polluted water
Answer:
a. air

Question 7.
Botulism is a kind of
a. heart disease
b. food poisoning
c. canned food
d. protozoa
Answer:
b. food poisoning

Question 8.
Ringworm is a disease of
a. heart
b. kidneys
c. skin
d. lungs
Answer:
c. skin

Question 9.
Which of these diseases spread through contact with .infected rats ?
a. Dengue
b. Sleeping sickness
c. Filariasis
d. Plague
Answer:
d. Plague

Question 10.
Protein deficiency leads to
a. marasmus
b. kwashiorkor
c. anaemia
d. scurvy
Answer:
b. kwashiorkor

Question 11.
Deficiency of vitamin K can lead to
a. blocked arteries
b. bleeding gums
c. haemorrhage
d. rickets
Answer:
c. haemorrhage

Question 12.
Lack of insulin leads to
a. atherosclerosis
b. diabetes
c. arthritis
d. goitre
Answer:
b. diabetes

B. Find the odd one out. Give reasons for your choice.
1. night blindness, scurvy, beriberi, typhoid
2. typhoid, chickenpox, polio, measles
3. weak bones and teeth, dehydration, lack of haemoglobin, night blindness
4. calcium, vitamin D, iron, magnesium
5. diabetes, goitre, arthritis, heart attack, cancer
6. malaria, plague, measles, dengue, yellow fever
Answer:
1. typhoid – Because typhoid is a water borne disease and all others are nutritional deficiency diseases.
2. typhoid – Because typhoid is a bacterial disease and all others are viral diseases.
3. dehydration – Because dehydration is the loss of water from the body and all others are deficiency diseases.
4. vitamin D – Because all others are minerals
5. goitre – Because it is a deficiency disease and all others are caused due to malfunctioning of body organs.
6. measles – Because all others are vector borne diseases.

C. Match the name of disease in the Column A with its cause in the Column B.

1. anaemia	a. deficiency of vitamin A
2. night blindness	b. deficiency of itamin B
3. rickets	c. deficiency of iodine
4. beriberi	d. deficiency of vitamin C
5. scurvy	c. deficiency of iodine
6. goitre	e. deficiency of iron
	f. deficiency of vitamin D

Answer:

1. anaemia	e. deficiency of iron
2. night blindness	a. deficiency of vitamin A
3. rickets	f. deficiency of vitamin D
4. beriberi	b. deficiency of itamin B
5. scurvy	d. deficiency of vitamin C
6. goitre	c. deficiency of iodine

D. Differentiate between

Question 1.
acquired diseases and congenital diseases.
Answer:
Acquired diseases :
1. These diseases develop after birth.
2. These diseases are not inherited from parents

Congenital diseases :
1. These diseases are present right from the birth.
2. These diseases are inherited from parents.

Question 2.
communicable diseases and non-communicable diseases.
Answer:
Communicable diseases :
1. Those diseases which can be passed by an infected person to a healthy person, directly or indirectly.
2. These are not caused by deficiency of certain nutrients or any other cause.
3. These are caused by microorganisms.

Non-communicable diseases :
1. Those diseases which are not passed by an infected person to a healthy person.
2. These diseases are caused either due to deficiency of certain nutrients or due to malfunctioning of organs.
3. These are not caused by microoganisms.

Question 3.
infectious diseases anc deficiency diseases.
Answer:
Infectious diseases
1. These diseases are caused by microor-ganisms.
2. These diseases can be transferred from infected person to healthy person.

Deficiency diseases :
1. These diseases are not caused by microorganisms.
2. These diseases cannot be transferred from healthy person to infected person.

E. Given below are the names of a few diseases. Classify them according to microorganisms which cause them.
sleeping sickness, rabies, food poisoning, botulism, typhoid, mumps, chickenpox, whooping cough, hepatitis, conjunctivitis, ringworm, amoebic dysentery, diphtheria, influenza, cholera, plague, yellow fever, pneumonia
Classify the above mentioned diseases according to their modes of transmission also.
Answer:

F. Use the key words given below to fill in the blanks in the following paragraph.
communicable
malaria
microorganisms
fungi
airborne
germs
bacteria
food poisoning
viral
protozoan
Anopheles
dog
The organisms which cannot be seen with naked eyes are called ………… Disease-causing microorganisms are called ………… Because of the small size, the viruses can easily be transmitted from one person to another through a sneeze as an ………….. infection. ………… are non-green plants which cause skin infection and …………. 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:
The organisms which cannot be seen with naked eyes are called microorganisms Disease-causing microorganisms are called germs Because of the small size, the viruses can easily be transmitted from one person to another through a sneeze as an airborne infection. Fungi are non-green plants which cause skin infection and food poisoning. 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.

G. Write short answers.

Question 1.
What are pathogens ?
Answer:
Microorganisms which cause communicable diseases are called pathogens, e.g. bacteria viruses, fungi and protozoa.

Question 2.
List the name of diseases caused by viruses.
Answer:
Measles, chickenpox, polio, hepatitis, AIDS, conjunctivitis, influenza are some of the diseases caused by viruses.

Question 3.
What is arthritis ?
Answer:
Arthritis is a disease of joints. In this disease there may be swelling, pain and stiffness of joints or knobby enlargement of the end and middle joints of fingers. It can also involves hip, knees and spine.

Question 4.
Define uremic poisoning
Answer:
Due to malfunctioning of kidneys, blood is not relieved of its waste products, and waste products get piled up, preventing removal of additional wastes from the cells, this condition is called uremic poisoning.

Question 5.
What are antibodies ?
Answer:
The proteins made by the immune system which attack the foreign bodies and prevent diseases, are called antibodies.

Question 6.
What kinds of first aid are given for first degree burn ?
Answer:
First degree bum are superficial bums. If it happens should apply cold water or dip the burnt area in cold water.

H. Answer in detail.

Question 1.
Name the various microorganisms which cause communicable diseases. Give two examples each of the diseases caused by these microorganisms.
Answer:
The various microorganisms which cause diseases are called pathogens or germs. These disease causing germs can be put in to four categories, that is :

(a) Bacteria : They are found in abundance in soil, water, air, food and in the bodies of other oganisms. Diphtheria,
typhoid are the diseases caused by them.

(b) Viruses : These microorganisms are on the borderline of the living and the non living. They are too small, can be seen with only electron microscope. Polio, Rabies etc. are the diseases caused by them.

(c) Fungi : These are non-green plants which may be single celled like yeast or multicellular like mushroom. Ringworm and athlete’s foot are the fungal disease.

(d) Protozoa : These are single celled micro-oiganisms. Amoebic dysentery, malaria are the diseases caused by protozoa

Question 2.
Explain the various ways by which communicable diseases spread.
Answer:
Communicable diseases are diseases that can be passed by an infected person to a healthy person either directly or indirectly. These diseases are also called infectious diseases. The communicable diseases spread from an infected person to a healthy person in the following ways. Airborne diseases – Many diseases of respiratory tract are transmitted through the air. Bacteria and viruses that infect the nasal passage, throat, windpipe and lungs, are present in saliva and mucus. A sneeze or a cough sprays droplets with germs into the air.

Droplet infection is a serious health problem. When people cough and sneeze in public places, they spray droplets of saliva into the air for others. Common cold, influenza, measles, tuberculosis, diptheria, whooping cough and chickenpox are some respiratory diseases whose germs are transmitted through air.

Waterborne diseases – Typhoid, dysentery, cholera and hepatitis are some infections that spread through water polluted with sewage. Drinking dirty water or using it to brush teeth or using ice made from unclean water leads to spread of waterborne diseases. Infections of ears, nasal passage and throat commonly spread through water in swimming pools.

Footborne diseases – Although cooking destroys many bacteria and other germs, most of the intestinal infections are caused by food. Fresh vegetables and fruits if eaten raw without washing them thoroughly can lead to stomach infections causing vomiting and diarrhoea. Consuming of stale, rotten and unhygienically stored food also causes food poisoning.

Canned food also contains certain bacteria which cause severe intestinal infections and food poisoning. Botulism is a kind of food poisoning that results from consumption of canned food. The bacteria gain entry into the cans, multiply in the absence of air and release toxic substances which are harmful for the nervous system.

Milk can also be a source of infection if it is not boiled properly before drinking. These days pasteurized milk is available in the market. In this process, milk is boiled for thirty minutes and is chilled immediately to kill germs. Meat which is not properly cooked can also carry larvae of worms which cause diseases.

Question 3.
How does an infection spread by contact ?
Answer:
Spread through contact – Many infections are carried from a wound on the body surface or body opening of one person to another by direct contact. Athlete’s foot, a fungal disease spreads by direct contact. Certain diseases spread b.y indirect contact. These diseases spread by consuming contaminated food and using articles previously handled by infected people.

Drinking glasses, coins, currency, door handles and many other things handled everyday can be source of infection. Ringworm, a skin disease spreads by direct or indirect contact with the patient. Intestinal infections and various viral infections like chickenpox and measles often spread rapidly to the entire family through direct as well as indirect contact.

Conjunctivitis, a viral disease which affects the eyes also spreads very fast. You may have experienced in your class that if one child suffering from conjunctivitis attends school without taking necessary precautions soon many children of the class get infected.

Question 4.
What is protein energy malnutrition ? Name two diseases caused due to protein energy malnutrition and given their symptoms.
Answer:
Protein energy malnutrition – Children in the age group of 1-5 years are affected by the deficiency of proteins or carbohydrates and fats or all. This condition is known as protein energy malnutrition. It lead to two diseases- kwashiorkor and marasmus.
Protein-energy malnutrition

A diet poor in protein during infancy and childhood results in a condition called kwashiorkor which retards the growth of young children. The affected children show the following symptoms.

• bulging eyes,
• protruding belly,
• frequent diarrhoea,
• water retention, that is, oedema,
• thin stick-like legs,
• discolouration of hair, and stunted growth and mental retardation.

When the diet is deficient in proteins as well as carbohydrates, the child suffers from marasmus. It occurs when children under the age of one year do not get food rich in proteins and carbohydrates. The affected children show the following .symptoms.

• body becomes lean and weak,
• dry, thin, wrinkled skin showing folds of loose skin,
• prominent ribs, and
• mental retardation.

Question 5.
What is diabetes ? What are its symptoms ?
Answer:
Diabetes – It is a disease caused by lack of the hormone insulin secreted by pancreas. A small group of cells called Islets of Langerhans in the pancreas manufacture insulin. When these cells do not produce enough insulin, the body can neither use sugar nor store it in liver in the form of glycogen.

The blood contains extra sugar but other body tissues lack it. The level of sugar in the blood rises to such an extent that some of it is passed out along with urine. The symptoms of diabetes include excessive thirst, frequent need to urinate, fatigue and loss of weight.

Question 6.
What is atherosclerosis ? How does it lead to coronary heart diseases ?
Answer:
In this disorder the inner lining of the arteries become hard, thick and rough. This process usually starts with building up of cholesterol on the inner walls of arteries. It decreases the internal diameter of the arteries, and thus reduces the flow of blood raising the blood pressure. As the supply of blood is reduced to a portion of heart muscle, heart attack occurs.

The blood vessels that supply blood to the heart muscles are called coronary arteries. Due to atherosclerosis. They become hard that result in reduction of blood supply to the heart muscles. This condition is referred to as coronary heart disease. It leads to angina which is a temporary chest pain.

Question 7.
What are the symptoms of rheumatoid arthritis and osteoarthritis ?
Answer:
Arthritis is a disease of joints. Although one may associate this disease with elderly people, large number of people below the age of 25 years suffer from it. It is of two types.
(a) Rheumatoid arthritis
(b) Osteoarthritis
(a) Rheumatoid arthritis involves swelling, pain andstiffness of the joints, especially the middle joints of the fingers. These joints may twist into various shapes. Normally people do not recover from this disease entirely. If the condition of the patient deteriorates, it results in joint deformities and crippling.
The most effective treatment is rest, to reduce inflammation and exercise which prevents deformity of joints. .

(b) Osteoarthritis normally occurs beyond middle age. It often leads to knobby enlargement of the end and middle joints of the fingers. It can also involves hip, knees and spine. Deformity results due to cartilage damage and bone swelling

Question 8.
What is cancer ? Name the agents which lead to cancer.
Answer:
Cancer is an uncontrolled growth of cells in body tissues. A growing mass of cancerous cells is called a malignant tumor. Cells of a cancerous growth often break off from the mass and travel to other body organs through blood or lymph.

The basic cause of cancer is unknown but conditions that may lead to cancer have been identified. These include overexposure to UV rays of sun and other types of radiation, contact with certain chemicals and cigarette smoking. The more cigarettes a person smokes, greater are the chances of developing lung cancer.

Although cancer may develop in any body tissue but lung cancer, breast cancer, skin cancer, blood cancer and cancers of mouth and throat are very common. An allergy is an unusual hypersensitivity of body tissue to certain substances.

Question 9.
What is allergy ? Name five allergens. List a few allergie reactions which take place in the body.
Answer:
Allergy is an unusual hypersensitivity of body tissue to certain substances. Those substances that bring about unusual sensitivity’ are called allergens.
Allergens may be certain
(a) food
(b) drugs
(c) cosmetics
(d) dust
(e) poller grains
(f) perfumes
An allergic reaction can occur when allergens are inhaled taken into our body through mouth or through direct skin contact. Reactions to allergies range from mild to severe. In mild reactions there can be slight itching, redness, or swelling of the skin. In a severe allergic reaction collapsing of circulatory system, heart failure and even death can result. Diarrhoea can also be an allergic reaction.

Eezema is a strong allergic reaction of the skin.
Hives – an allergic reaction recognized by red, raised areas on the skin.
Asthma – allergy to pollens, dust, dog, cat, dandruff or certain foods that results in to difficult breathing and wheezing.

Question 10.
What are the effects of alcohol on human body ?
Answer:
Beer, wine and hard liquors are commonly consumed by people. Alcohol slows down the activity of the brain. When a person takes a drink containing alcohol, the alcohol is absorbed from the small intestine into the blood stream and reaches the brain.
When taken in small quantities, alcohol relaxes the brain. But when larger quantity is consumed, the control system of the body becomes weak. It affects muscular coordination and as a result the person feels difficulty in speaking clearly because he or she cannot control the movement of the tongue.

A person finds it difficult to walk because he cannot control the muscles of the legs. A person may have blurred vision. The reactions to a situation become slow. A person driving under the influence of alcohol has more chances of accident since his coordination is slow and reaction time is more and it affects the judgement on the road. People who cannot control their dependence on alcohol are called alcoholics. Liver cirrhosis is a common disease caused in persons who have long-term 1 dependence on alcohol.

Question 11.
What general precautions should not take to prevent diseases ?
Answer:
Once we know the cause of a disease and the way it spreads, it becomes easy to prevent the disease by taking certain precautions.
a. Exposed food items should not be eaten since flies sit on such food and transmit diseases. We should never eat
% stale food.

b. Drinking water should never be left uncovered. If possible, we should drink filtered or boiled water. It should always be stored in a clean container with a cover.

c. There should not be any stagnant water in and around your house which promotes be kept separate.

d. Food and articles used by a patient should be kept separate.

e. Surroundings should be kept clean. Garbage should be thrown in covered bins.

f We should take care of personal cleanliness. We should wash our hands with soap before eating food.

g. Regular immunization against diseases should be done to avoid infection. The persons suffering from a communicable disease should take precautions to prevent further spreads of the disease. They should cover their mouth with handkerchief while sneezing or blowing nose. No one should spit in public places.

Question 12.
How does vaccination prevent diseases ?
Answer:
A vaccine is a small amount of the disease causing microorganisms that have been weakened or killed so that they will not cause the disease. A vaccine can be injected or taken orally. Injecting or swallowing a vaccine is called vaccination Vaccination is a way of preventing pathogenic microorganisms from causing a disease. It works by making the body’s immune system produce antibodies against the disease causing microbes present in the vaccine.

The antibodies attack and destroy the weakened microbes as they enter the body. These antibodies remain in the blood to fight off an attack by that particular microorganism in future. Thus, the body develops immunity to the particular disease.
Vaccine are given against diphtheria, whooping cough, tetanus, polio, measles and tuberculosis to children between the ages of 6 weeks to 6 years. Few of these vaccinations have to be repeated after a few years, as they do not give immunity for life.

I. Give reasons for the following :

Question 1.
Deficiency diseases are called non-communicable diseases.
Answer:
Deficiency disease are caused due to deficiency of certain nutrients. These are not caused by microorganisms. They cannot pass from person to person so they are called non-communicable diseases.

Question 2.
There are more chances of catching cold, influenza and measles in public places.
Answer:
As bacteria and virus are transmitted through the air. Droplet infection is a serious health problem. When people cough and sneeze in public places, they spray droplets of saliva in to the air for others. So the germs are transmitted through air from infected person to : healthy person.

Question 3.
You are advised not to eat food from the roadside vendors.
Answer:
We should not eat from the roadside vendors as the food is not properly covered, houseflies and mosquitoes sit on food articles which transfer disease causing germs to the food articles. When we eat this food we may fall sick. Food is unhygienic and unhealthy.

Question 4.
It is important to make sure that swimming pool water is clean.
Answer:
Infection of ears, nasal passage and throat spread through water in swimming pools. Skin infections may also occurs, to avoid these infections we should make sure that swimming pool water is clean.

Question 5.
There should be no stagnant water near your house.
Answer:
Stagnant water promote breeding of mosquitoes, which spread diseases like malaria and dangue, so there should be no stagnant water near our house.

Question 6.
You should eat balanced diet.
Answer:
We should eat balanced diet if we will not eat balanced diet we will be undernourished. Deficiency of specific nutrients causes deficiency diseases. One should eat balanced diet to stay healthy.

Question 7.
A child who was suffering from conjunctivitis was sent home by her teacher.
Answer:
Conjunctivities is a viral disease of eye which spreads very fast. So to prevent spreading of this disease to the rest of students teacher sent the student to home.

Question 8.
A child bitten by a dog should be immediately taken to a doctor.
Answer:
Rabies, a dreadful viral disease is transmitted to humans by the bite of a dog. The virus destroys the cells of the brain and spinal cord, the patient die a painful death due to restlessness, choking, convulsions and inability to swallow even liquids. So a child bitten by dog should be immediately taken to a doctor for antirabies vaccination.

Question 9.
A person suffering from angina should get the cholesterol level checked up.
Answer:
Angina is a temporary chest pain which results due to deposition of cholestrol in the inner wall of arteries, which result in reduced blood supply to heart. It can lead to coronary heart disease. So a person suffering from angina should get the cholestrol level checked up.

Question 10.
Cigarette smoking is injurious to health.
Answer:
When a person smokes cigarette, the hot smoke irritates the tissues in the mouth, throat, bronchi and lungs. The cigarette smoke contains nicotine, tar and carbon monoxide. It may cause umg cancer, breathing problem, darkening of teeth, increase blood pressure. So the cigarette smoking is injurious to health

Living Science Biology Class 8 ICSE Solutions.