Selina Concise Solutions for Chapter 8 Diseases and First Aid Class 8 Biology ICSE

Review Questions

Multiple Choice Questions

1. Put a tick mark (✓) against the correct alternative in the following statements:

(a) A mosquito is a vector for
1. Typhoid
2. Cholera
3. Malaria
4. Jaundice
3. Malaria

(b) Dengue is caused by a
1. Protozoan
2. Virus
3. Worm
4. Fungus
2. Virus

(c) The idea of vaccination was conceived by
1. Charles Darwin
2. Alexander Flemming
3. Issac Newton
4. Edward Jenner
4. Edward Jenner

(d) Which one of the following is not a psychotropic drug?
1. Morphine
2. Cocaine
3. Heroin
4. Penicillin
4. Penicillin

(e) Which one of the following is a communicable disease?
1. Measles
2. Cancer
3. Heart stroke
4. Allergy
1. Measles

(f) Cataract is a disease of : –
1. Ears
2. Nose
3. Eyes
4. Throat
3. Eyes

(g) Infectious diseases can be prevented by:
1. Medicines
2. Proper food
3. Immunisation
4. Exercise
3. Immunisation

(h) Which one of the following is a genetic disease?
1. Scurvy
2. Leukemia
3. Goitre
4. Haemophilia
4. Haemophilia

(i) Which one of the following is a degenerative disease?
1. Thalassemia
2. Beri-beri
3. Cataract
4. Diabetes
3. Cataract

(j) Pellagra is one disease caused by the deficiency of:
1. Vitamin B3
2. Vitamin B1
3. Vitamin C
4. Vitamin D
1. Vitamin B3

(k) Hay fever and asthma are
1. Deficiency diseases
2. Genetic diseases
3. Organic diseases
4. Allergy diseases

(i) Which one of the following vitamin deficiency diseases can be cured by eating a diet which includes carrot, yellow fruits, vegetables, butter, milk, fish?
1. Beri-beri
2. Dermatitis
3. Night blindness
4. Scurvy
3. Night blindness

Short Answer Questions

1(a). What is a non-communicable disease?
The diseases which are caused due to improper functioning of the body organs e.g. diabetes, heart attack. They are not caused by germs and not transmitted from one to another.

1(b). What are communicable diseases?
Those disease which spread from one person to another by the entry of microorganisms are known as communicable diseases.

1(c). How can we control spreading of diseases by mosquitoes and houseflies?
We can control spreading of diseases by mosquitoes and houseflies by using repellants, throwing garbage in covered bins, avoiding stagnation of water and checking breeding of these insects.

1(d). Public hygiene is equally important as personal hygiene. Give reasons.
Keeping oneself clean is personal hygiene. But public hygiene is equally important as dirty surrounding may lead to more of houseflies, mosquitoes and other insects which are major vectors of many communicable diseases. Clean surrounding also provides good mental health as it soothes our mind.

1(e). What is a deficiency disease?
These disease are caused by lack of nutrients, vitamins, minerals as a anaemia, goitre.

1(f). Biting nails should be strictly avoided. Give reason.
Nail biting may cause many disease as the dirt has many bacteria causing diseases. Nails should be cut from time to time to save from diseases.

1(g). Regular exercise and proper rest is a must. Give reason.
Regular exercise keeps our body strong and immune to many diseases, rest refreshes our body.

1(h) Children eating more of fast food tend to suffer from obesity (overweight). Comment.
Fast food like pizza, burger, patty, oily foods etc. have much carbohydrates and fats. Children eating these become more and more fat and gain weight soon as they do not do much of physical work.

2. Name the following:

2(a) A viral disease caused due to unhealthy sexual contact

2(b) A disease caused due to Plasmodium

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

2(d) Two viral diseases caused by mosquito bites
Dengu, Chikungunya.

2(e) Any droplet — borne disease.
Amoebiasis, Cholera, Hepatitis A.

2(f) A viral disease caused by the bite of a dog

2(g) A disease due to choking of coronary artery

2(h) Two diseases caused due to deficiency of protein in the diet of a child.
Kwashiorkor and marasmus.

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

Disease, immunisation, pathogen, AIDS, vaccination, vector.
  • Disease: Disease is a departure from normal health due to structural or functional disorder of the body. Disease may be due to deficiency of nutrients or malfunctioning of organs or 1 genetic disorders, improper metabolic activity, or allergies, or cancer and mental illness as diabetes, haemophilia, leukemia, schizophrenia.
  • Immunisation: It means, we make the body immune to certain diseases by introducing respective weakened germs into the body. Thus we develop resistance to the concerned disease this process is called immunisation. The germs or the material introduced into the body to make it resistant to the concerned disease is called vaccine. This produces antibodies in the body of the person and the person can be saved by these antibodies. The vaccine can be given by the injection or orally as polio drops, tap vaccine for typhoid, BCG vaccine for tuberculosis.
  • Pathogens: The germs that cause diseases to human beings and to other animals and plants are called pathogens. They spread the diseases from person to person or through the air or through the articles of the diseased persons. Pathogens may be different kinds of bacteria, viruses, fungi, protozoans or worms.
  • AID’S (Acquired Immune Deficiency Syndrome): It is a viral disease caused by the virus called HIV (Human immuno deficiency virus) This virus makes the defence mechanism of the human body very weak. The immune system in the body as W.B.C. becomes weak. Thus the person catches the infectious diseases very easily. This disease spreads through sexual contact as one of the partner may be carrier of the disease. It may spread through the blood transfusion and infected syringes, blades of the barbers, it may infect the developing baby through the blood by the mother. It is very deadly disease.
  • Vaccination: Vaccination is a method of making the body immune to a particular disease by injecting killed or weakened disease causing microbe into a body to stimulate the formation of antibodies and develop immunity to that disease causing microbe.
  • Vector: A vector is an organism that carries disease causing microbes (pathogens) from one host to another. They are the carriers of infection. Example: Mosquito, housefly, etc.

P.Q. Fill in the blanks by selecting suitable words given below:
(clotting, goitre, insuline, rickets, iron, proteins)

(a) Anaemia is caused due to the deficiency of _____.
(b) Deficiency of Vit. D causes _____ in children.
(c) Deficiency of iodine in the diet may cause ______.
(d) Diabetes is caused due to under secretion of ______.
(e) Kwashiorkor is caused due to the deficiency of _____.
(f) Haemophilia is a disease caused due to slow _____ of the blood.
(a) Anaemia is caused due to the deficiency of iron.
(b) Deficiency of Vitamin D causes rickets in children.
(c) Deficiency of iodine in the diet may cause goitre.
(d) Diabetes is caused due to under secretion of insulin.
(e) Kwashiorkor is caused due to the deficiency of proteins.
(f) Haemophilia is a disease caused due to slow clotting of the blood.

P.Q. Find the odd one out:

(a) Typhoid, cholera, jaundice, tuberculosis, tetanus.
Jaundice is odd one

(b) Cold, AIDS, plague, malaria, measles.
Malaria is odd one.

(c) Scurvy, rickets, haemophilia, pellagra, night blindness.
Haemophilia is odd one.

(d) Proteins, carbohydrates, fats, minerals, cancer.
Cancer is odd one.

P.Q. Fill in the blank in the following table:

Long Answer Questions

1. What is vaccination? Mention the four ways in which vaccine’s are prepared, giving the name of one disease for which each type of vaccine is used.
For developing resistance in the body we introduce germs or germ substances in the body to develop resistance in the body against a particular disease. The material introduced into the body is called vaccine, this practice is called prophylaxis.
The germ or the germ substance is put into the body orally as polio drops or it is introduced by injection as TAB vaccine. Vaccine or vaccination was attached with small pox, but it is now used in a general sense.

  1. Killed germs are introduced into the body These act as vaccine for TAB, vaccine for typhoid, Salk’s vaccine for poliomyelitis. Rabies vaccine for dog bite.
  2. Living weakened germs: The living germs are treated in such a way that they become very weak and as such, they cannot cause the disease. They can induce antibody formation such as the vaccine for measles and the freezed dried BCG vaccine for tuberculosis.
  3. Living fully virulent germs: These virulent germs in small doses are introduced into the body as vaccine and these produce antibodies in the body and these do not allow the germs of particular type to cause that disease: In this vaccination the person is inoculated with cowpox virus. It is very similar to small pox virus.
  4. Toxoids: Toxoids are prepared from the extracts., of toxins secreted by bacteria. These toxins are poisons and these are made harmless by adding formalin into them. They retain their capacity and as a result when introduced into the body they produce antibodies into the body and do not allow the germs to grow in the body as vaccines for diphtheria and tetanus.

2. Burns can be superficial burns, deep burns or chemical burns. What emergency care you would suggest in each case.
When one gets burnt up accidentally one should not pull clothes from the burnt area and one should not cut the blisters. One should apply butter, vaseline or ointment.
  • Superficial burns: When there are superficial bums, put cold water on it and apply some oily substance, burnol, castor oil, vaseline, butter etc.
  • Deep burns: When there are deep bums do not put cold water on the burnt area. Seek the help of hospital and one should be kept under the treatment of some expert doctor of skin.
  • Chemical burns: In case of chemical burns i.e., due to acid and other chemicals, wash with running water for 10 minutes and then cover with dressing.

3. Describe the ways in which communicable diseases are transmitted through various indirect methods.
Indirect methods of transmission of communicable diseases:
  1. Using items used by the infected persons: The healthy persons may be infected by using the articles like towel, hanky, utensils, bedding used by the patient infected by the communicable diseases. Diseases like tuberculosis, ring worm; common cold, influenza are transmitted by this method.
  2. Contaminated food and water: Diseases like dysentery, cholera spread through the contaminated food and water. Flies sitting on the food, if taken by a healthy person may be infected by the germs which may cause vomiting and loose motions. Similarly water and food infected by entamoeba may cause dysentery to persons who may take contaminated food.
  3. Vectors or carriers: Organisms like mosquitoes and house flies, ticks carry germs from the source of infection and pass on the germs to the normal persons and thus they are infected by diseases like malaria, cholera, plague. These organisms which carry the disease are called vectors and are not infected themselves.
    Mosquitoes suck blood and carry the disease causing protozoans from infected persons to healthy persons.
    Similarly houseflies carry the germs from garbage and sewage to the food. If this food is taken by the persons they become prey to typhoid and other diseases.
  4. Air: One sneeze from a person infected by cold may give billions of germs which are carried by air and may infect the healthy person. Tuberculosis passes from one person to other by coughing or sneezing of the infected person.
    These germs remain suspended in the air and persons may be infected by these spores or germs. Common cold, measles, diptheria, chicken pox.

4. Given a crossword puzzle. Read the clues across and clues downward, and fill up the blank squares. Check up your performance with the correct solution given at the end.

Clues across
1. Category of pathogen that causes diseases, like common cold and mumps.
2. These may readily grow in your hair, if you do not wash it regularly.
3. This is the vaccine for preventing tuberculosis.
4. Cover this part of your body by a handkerchief while sneezing to prevent droplet infection to others.
5. The disease pertussis is popularly known as whooping
6. One of the most common insects which visits our exposed foods and contaminates them.
7. A disease that weakens body’s defence system
8. Germ or germ – substance introduced into the body to prevent occurrence of an infectious disease.
9. A disease in which the eyes, the skin and the urine turn yellow.
10. An organ usually affected by tuberculosis.
11. A disease caused by the bite of an infected dog, and which affects the central nervous system.


Additional Question

I. Multiple choice questions. Tick (✓) the correct choice:

1. Which of the following is a disease caused by bacteria?
1. cholera
3. malaria
4. rabies
1. cholera

2. Which of the following is not a viral disease?
1. pneumonia
2. measles
3. polio
4. rabies
1. pneumonia

3. Ringworm is a disease caused by
1. protozoa
2. bacteria
3. virus
4. fungi
4. fungi

4. Kwashiorkor is caused by
1. smoking
2. worms
3. virus
4. imbalance in diet
4. imbalance in diet

II. Fill in the blanks :

1. Over-eating causes a disease called _____.
2. Food poisoning is caused by _____.
3. One of the diseases caused by protozoa is _____.

1. Over-eating causes a disease called obesity.
2. Food poisoning is caused by bacteria.
3. One of the diseases caused by protozoa is malaria.

III. Find the odd one out, giving reason:
Pneumonia, cholera, leprosy, measles Measles:

Measles: is the odd-one out as it a disease caused by a virus while the rest three are bacterial diseases.

IV. Define the following:

  1. Diseases
  2. Malnutrition
  1. Diseases: Any disorder or abnormal working of an organ, part or system of the body leads to illness called as disease.
  2. Malnutrition: The condition of nutrition in which the food is either in inadequate quantity or in excess or it lacks in some essential nutrient is called malnutrition.

V. Name the Following:

1. Two diseases each caused by bacteria, protozoa and virus.

Two diseases caused by bacteria are pneumonia and cholera. Two diseases caused by protozoa are malaria and amoebiasis. Two diseases caused by virus are chicken pox and AIDS.

2. Organism which causes malaria.

Protozoa (called Plasmodium).

3. Cause of obesity.

Excess of food (ovenutrition).

VI. Answer the following questions:

1. List the causes of diseases.
Diseases develop due to a number of causes such as:

  1. imbalances in the diet.
  2. infection by micro-organisms.
  3. malfunctioning of body organs.
  4. allergic reactions to substances in the environment.
  5. social factors such as smoking, alcoholism, drug addiction, unhealthy life style.

2. What are deficiency diseases?

The diseases caused by inadequate intake of food or the lack of some essential nutrient in our diet are called deficiency diseases.

3. Differentiate between undernutrition and malnutrition.



1. It is a condition of nutrition where food is inadequate.

1. It is condition of nutrition where food is either inadequate, or excess or lacks some essential nutrient.

2. It leads to deficiency diseases.

2. It leads to deficiency diseases and obesity.

3. Undenutrition is a form of malnutrition.

3. Malnutrition has many forms like undenutrition, overnutrition or imbalance of nutrients in diet.

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