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

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1. Match the diseases in Column I with their categories in Column II

   Column I	Column I
   Plague	Sporadic
   Malaria	Pandemic
   Goitre	Epidemic
   AIDS	Endemic

   Solution:

   Column I	Column I
   Plague	Epidemic
   Malaria	Sporadic
   Goitre	Endemic
   AIDS	Pandemic

2. Classify the following diseases into communicable and non-communicable diseases: cholera, beri-beri, colour blindness, diabetes, malaria, plague, heart-attack.

   1. Communicable ________
   2. Non-communicable _________

   Solution:

   The table classifies the diseases into communicable and non-communicable:

   Communicable	Non-communicable
   Cholera	Beri-beri
   Malaria	Colour-blindness
   Plague	Diabetes
   	Heart-attack

Multiple Choice Type

1. A disease widely spread worldwide is known as

   1. Endemic
   2. Epidemic
   3. Pandemic
   4. Sporadic

   Solution:

   (c) Pandemic

   These are the diseases that are widely distributed across the world. Example – AIDS

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

   1. Brief
   2. Beri-beri
   3. Bacteria
   4. Bacillus

   (d)Bacillus

   It is a vaccination primarily used to treat Tuberculosis.

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

   1. Poliomyelitis
   2. Mumps
   3. Rabies
   4. AIDS

   Solution:

   1. AIDS

   The AIDS virus is highly infective.

4. The vector that transmits the malarial pathogen is:

   1. Culex mosquito
   2. Housefly
   3. Anopheles mosquito
   4. Entamoeba

   Solution:

   (c)Anopheles mosquito

   The infective stage of the parasite is transmitted through the bite of the female Anopheles mosquito along with its saliva.

5. Amoebiasis is caused by the protozoan:

   1. Amoeba proteus
   2. Euglena
   3. Plasmodium
   4. Entamoeba

   Solution:

   (d)Entamoeba

   It is a kind of amoeba that causes amoebic dysentery.

6. BCG vaccine provides immunity against:

   1. Tetanus
   2. Cholera
   3. AIDS
   4. Tuberculosis

   Solution:

   (d)Tuberculosis

   BCG is used in the prevention of Tuberculosis caused by Mycobacterium tuberculosis

7. The expanded forms of AIDS is:

   1. Active Immunity Deficiency Syndrome
   2. Acquired Immuno Deficiency Syndrome
   3. Acquired Immuno Deficiency Status
   4. Active Immuno Deficiency Syndrome

   Solution:

   (b) Acquired Immuno Deficiency Syndrome

   AIDS is a pandemic disease caused by HIV.

Very short answer type

1. Mention whether the following statements are true (T) or false (F).
   1. Filiariasis is transmitted by the housefly T/F
   2. Malaria is caused by a protozoan T/F
   3. BCG vaccine is used for chicken pox T/F
   4. Louis Pasteur discovered a cure for malaria T/F
   5. AIDS is caused by a bacterium. T/F
   6. HIV is a serious disease, usually fatal. T/F
   7. AIDS is not transmitted by contact with a patient’s clothes T/F
   8. Chicken pox and hepatitis are bacterial diseases. T/F
   9. Goitre is endemic in sub-Himalayan regions of India. T/F
   10. AIDS is caused by a fungus T/F
   11. Hay fever and asthma are allergies T/F
   12. Smallpox still occurs in India T/F
   13. The disease Filiariasis is caused by the bite of female anopheles mosquito T/F

   Solution:

   1. The statement is false. Filiariasis is transmitted by Culex mosquito
   2. The statement is true
   3. The statement is false. BCG vaccine is used to treat tuberculosis
   4. The statement is false. Louis Pasteur discovered a cure for rabies
   5. The statement is false. AIDS is caused by a virus (HIV).
   6. The statement is true.
   7. The statement is true.
   8. The statement is false. They are not bacterial but viral diseases.
   9. The statement is true.
   10. The statement is false. AIDS is caused by a virus (HIV).
   11. The statement is true.
   12. The statement is false. Smallpox has been eliminated from India.
   13. The statement is false. The disease is caused by the filarial worm Wuchereria bancrofti.

2. Write the full form of AIDS.

   Solution:

   The full form of AIDS is – Acquired Immuno Deficiency Syndrome

3. Name the following:

   1. Category of pathogen that causes diseases, like common cold and mumps ________
   2. The vaccine for preventing tuberculosis ________
   3. An organ usually affected by tuberculosis ________
   4. A disease that weakens body’s defense system against infections ________
   5. Germ of germ-substance introduced into the body to prevent occurrence of an infectious disease ________
   6. The vector responsible for transmission of sleeping sickness ________
   7. The microorganism that requires a host to produce________
   8. The popular name of the disease Filiariasis ________

   Solution:

   1. Viruses
   2. BCG
   3. Lungs
   4. AIDS
   5. Vaccine
   6. Tsetse fly
   7. Virus
   8. Elephantiasis

Short Answer Type

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

   Solution:

   The definitions are as follows:

   Infection – It is the transmission of diseases from one person to another.

   Pathogen – A pathogen is a disease-causing micro-organism.

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

   Allergen – An allergen is an antigenic substance that is capable of producing immediate hypersensitivity allergy.

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

   Solution:

   The different ways in which infectious diseases can spread are:

   • Direct contact – It can spread from person to person, zoonotic diseases (spread between animals and humans), from mother to child.
   • Indirect contact
   • Different media of transmission such as air, water etc
   • Carriers/vectors – mosquitoes
   • Contaminated food and water
3. Name any four non-infectious diseases and their causes.

   Solution:

   Four infectious diseases and their causes are as follows:

   Name of the disease	Cause
   Diabetes	Metabolic reasons
   Arthritis	Degenerative disease
   Hay fever	Allergies
   Beri-beri	Nutritional deficiency

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

   Solution:

   It is because several diseases are transmitted through direct contact or through modes such as air, water etc. Hence to take precautionary measures and protect others from infections furthermore, it is necessary to know how the germs move out of the body of a patient.

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

   Solution:

   The causative of AIDS is HIV – Human Immunodeficiency Virus. The disease can be transmitted by the following means:

   • Sexual intercourse
   • Contaminated blood transfusions
   • Mother to child transmission
   • Injection needles

Long Answer Type

1. Write very briefly about the following:

   1. BCG
   2. Incubation period
   3. Chicken pox
   4. Hepatitis A

   Solution:

   1. BCG – BCG (Bacillus Calmette Guerin) is a vaccine that is used to treat Tuberculosis (TB) which is a bacterial disease as it develops immunity to TB.
   2. Incubation period – It is the period between the entrance of the germs and the appearance of the first symptoms of the disease. Incubation period of Tetanus of 4-20 days.
   3. Chicken pox – It is caused by the Herpes Varicella zoster virus and is a viral disease. It rapidly spreads through close contact with the person infected.
   4. Hepatitis A – It is caused by the Hepatitis A virus and is a viral disease that results in liver inflammation. It is transferred primarily through contaminated water and food.

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

   Solution:

   The causes, symptoms and preventive measure of malaria, chicken pox and tuberculosis are given below:

   Name of the disease	Causes	Symptoms	Preventive measures
   Malaria	Plasmodium	High fever Chills Profuse sweating Nausea Vomiting Fatigue Body pain Severe headache	Avoid mosquito bites using mosquito repellants and nets Avoid being around stagnant water
   Chicken pox	Varicella zoster	Rashes near the back and the chest eventually spreading to arms, face, legs and head	Vaccination of live attenuated vaccine having Varicella to children.
   Tuberculosis	Mycobacterium tuberculosis	Afternoon fever Persistent cough Weight loss Blood in mucous Chest pain Fatigue	Isolate the patient, BCG vaccination.

Selina Solutions for class 9 Biology Chapter 16 – Diseases: Cause and Control

ICSE Class 9 Biology Chapter 16 – Diseases: Cause and Control chapter is classified under Unit – VI of Biology textbook – Health & Hygiene. Health refers to the normal and healthy state of the body in all the three aspects namely – physical, mental and social wellness while Hygiene pertains to the conditions and practices in order to maintain health and prevent any chance of diseases.

The unit Diseases – Cause and Control discusses the various aspects of diseases. It provides a brief introduction to communicable and non-communicable diseases (infectious and non-infectious diseases) the different modes of transmission of diseases(water, air, food, insect-borne) endemic, pandemic and sporadic diseases.

Different diseases caused by different pathogens such as protozoans, bacteria(tuberculosis, cholera, typhoid), viruses(AIDS, chickenpox, hepatitis etc. ).

The chapter covers the following types of questions:

• Multiple-choice questions
• State whether true/false
• Fill ups
• Very short answer type questions
• Short answer type questions
• Long answer type questions

List of subtopics covered in Chapter 16 – Diseases: Cause and Control

List of Exercise

Selina Solutions for class 9 Biology Chapter 16 – Diseases: Cause and Control

Disease is a condition in which the normal functioning of the body is disturbed. The chapter focuses briefly about the categories of diseases based on

• Extent of occurrence
• Communicability – Infectious and non-infectious diseases

Diseases are caused by different agents such as bacteria, protozoa, viruses parasitic worms(Taeniasis, Filariasis, ascariasis) etc. the student understands few diseases, their possible causatives, symptoms, and preventive measures.

Some common viral diseases such as AIDS, chickenpox, hepatitis etc are presented in the chapter. Lastly, students are presented with the differences between viruses and bacteria so as to be able to tackle these diseases with the respective precautionary measures.

Key Features of Selina Solutions for class 9 Biology Chapter 16 – Diseases: Cause and Control

• Selina solutions is a free tool and is readily accessible
• Prepared by a team of experts at BYJU’S as per the latest ICSE syllabus for class 9
• The use of language is student-friendly
• Tables are used wherever necessary
• Diagrams provided to understand concepts better