Selina ICSE Solutions for Class 9 Biology Chapter 16 - Diseases: Cause And Control

Selina ICSE Solutions for Class 9 Biology Chapter 16 - Diseases: Cause And Control

Exercise 1

A. Multiple choice  Types.

1. A disease widely spread worldwide is known as

(a) endemic
(b) epidemic
(c) pandemic
(d) sporadic

2.The letter B in the name BCG vaccination stands for

(a) Brief
(b) Beri-beri
(c) Bacteria
(d) Bacillus

3. Use of disposable syringes for injecting medicines, etc. is specially advised to prevent

(a) Poliomyelitis
(b) Mumps
(c) Rabies
(d) AIDS

4. The vector that transmits the malarial pathogen is:

(a) Culex mosquito
(b) Housefly
(c) Anopheles mosquito
(d) Entamoeba

5.  Amoebiasis is caused by the protozoan:

(a) Amoeba proteus
(b) Euglena
(c) Plasmodium
(d) Entamoeba

Solution A.

1. (c) pandemic
2. (d) Bacillus
3. (d) AIDS
4. (c) Anopheles mosquito
5. (d) Entamoeba

B. Very Short Type Answer

1. Mention whether the following statements are true (T) or false (F).

(a) Filariasis is transmitted by the housefly. T/F

(b) Malaria is caused by a protozoan. T/F

(c) BCG vaccine is used for chicken pox. T/F

(d) Louis Pasteur discovered a cure for malaria. T/F

(e) AIDS is caused by a bacterium. T/F

(f) HIV is a serious disease, usually fatal. T/F

(g) AIDS is not transmitted by contact with a patient's clothes. T/F

(h) Chicken pox and hepatitis are bacterial diseases. T/F

(i) Goitre is endemic in sub-Himalayan regions of India. T/F

(j) AIDS is caused by a fungus. T/F

(k) Hay fever and asthma are allergies. T/F

(l) Smallpox still occurs in India. T/F 

(m) The disease filariasis is caused by the bite of the female anopheles mosquito.

Solution B.1.

(a) F (False). Filariasis is transmitted by the Culex mosquito.

(b) T (True)

(c) F (False). BCG vaccine is used for tuberculosis.

(d) F (False). Louis Pasteur discovered a cure for rabies.

(e) F (False). AIDS is caused by a virus.

(f) T (True)

(g) T (True)

(h) F (False). Chicken pox and hepatitis are viral diseases.

(i) T (True)

(j) F (False). AIDS is caused by HIV virus.

(k) T (True)

(l) F (False). Smallpox has been eradicated from India.

(m) F (False). The disease filariasis is caused by the filarial worm Wuchereria bancrofti.

2. Write the full form of AIDS.

Solution B.2.

AIDS : Acquired Immunodeficiency Syndrome

3. Name the following:

(a) Category of pathogen that causes diseases like common cold and mumps.

(b) The vaccine for preventing tuberculosis.

(c) An organ usually affected by tuberculosis.

(d) A disease that weakens the body's defence system against infections.

(e) Germ of germ-substance introduced into the body to prevent occurrence of an infectious disease.

(f) The vector responsible for transmission of sleeping sickness.

(g) The microorganism that requires a host to reproduce.

(h) The popular name of the disease filariasis.

Solution B.3.

(a) Viruses

(b) BCG

(c) Lungs

(d) AIDS

(e) Vaccine

(f) Tsetse fly

(g) Virus

(h) Elephantiasis

C. Short Type Answer.

1. Define the terms infection, pathogen, incubation period and allergen.

Solution C.1.

Infection: The transmission of disease from one person to another is called infection.

Pathogen: Disease-causing micro-organism is called a pathogen.

Incubation period: Incubation period is the period between the entry of germs and the appearance of the first symptoms of the disease.

Allergen: An antigenic substance capable of producing immediate hypersensitivity allergy is called an allergen.

2. What are the different ways in which infectious diseases can spread?

Solution C.2.

The different ways in which infectious diseases can spread are as follows:

      • Direct contact: Person to person, animal to person and expected mother to child

      • Indirect contact: Doorknob, phone, etc.

      • Droplet transmission: Sneezing, coughing, etc.

      • Particle transmission: Air particles can transfer infectious diseases

      • Bites and Stings: Mosquitoes, lice, ticks, etc.

      • Food Contamination: Food, beverages, etc.

3. Name any four non-infectious diseases and their causes.

Solution C.3.

       

4. Why is it important to know how the germs leave the body of a patient?

Solution C.4.

It is important to know how the germs leave the body of a patient as there are some diseases and infections which are transmitted through air, water or just by direct contact. Therefore, to take precautions and protect others from further infections, it is a must to know how the germs leave the body of an infected person.

5. Name the causative germ of AIDS. How is this disease transmitted?

Solution C.5.

Causative germ of AIDS:

HIV (Human immunodeficiency virus)

Transmission of AIDS:

(a) Sexual intercourse
(b) Mother to child transmission
(c) Contaminated blood transfusions

D. Long Type Answer

1. Write very briefly about the following:

(a) BCG
(b) Incubation period
(c) Chicken pox
(d) Hepatitis A

Solution D.1.

(a) BCG: It is a vaccine which is effective against the bacterial disease tuberculosis (TB). It develops immunity to TB. BCG stands for Bacillus Calmette Guerin.

(b) Incubation period: It is the period between the entry of germs and the appearance of the first symptoms of the disease. Example: Incubation period of pneumonia is 1-3 days.

(c) Chicken pox: It is a viral disease caused by the Herpes Varicella zoster virus. It spreads rapidly by close contact with an infected person. A live attenuated vaccine containing Varicella is administered to children of 12-18 months for active immunisation.

(d) Hepatitis A: It is a viral disease caused by Hepatitis A virus which results in inflammation of the liver. It has an incubation period of 14-45 days. It is mainly transmitted through contaminated food and water.

2.What are the causes and symptoms of malaria, chicken pox and tuberculosis? How can these diseases be prevented?


Solution D.2.

Selina ICSE Solutions for Class 9 Biology Chapter 16 - Diseases: Cause And Control