Diseases Cause and Control Long Answer Biology Class-9 ICSE Selina Publishers

Diseases Cause and Control Long Answer Biology Class-9 ICSE Selina Publishers Solutions Chapter-16. Step By Step ICSE Selina Concise Solutions of Chapter-16 Diseases Cause and Control with Exercise-16 including MCQs, Very Short Answer Type, Short Answer Type, Long Answer Type and Structured/Application Questions Solved Visit official Website CISCE for detail information about ICSE Board Class-9.

Diseases Cause and Control Exe-16 Long Answer Biology Class-9 ICSE Concise Selina Publishers

Board ICSE
Publications Selina Publication
Subject Biology
Class 9th
Chapter-16 Diseases Cause and Control
Book Name Concise
Topics Solution of D. Long Answer Type
Academic Session 2023-2024

D. Long Answer Type 

Diseases Cause and Control Class-9 Biology Concise Solutions  

Page 176

Question 1.

Write very briefly about the following:

(a) BCG

(b) Incubation period

(c) Chicken pox

(d) Hepatitis A


(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:

 Hepatitis A 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. This is mainly transmitted through contaminated food and water.

Question 2.

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


Disease Causative
Symptoms Prevention
Malaria Protozoan,
Chills, high fever, profuse sweating, severe headache, nausea, vomiting, fatigue and body pain Destruction of mosquitoes at all
and avoid mosquito bites by
using mosquito nets or repellents
Chicken pox Virus,
Highly irritating rashes near the chest and back, gradually spreading to the arms, legs, face and head Active immunisation by administering live attenuated vaccine containing Varicella
Tuberculosis Bacterium,
Mycobacterium tuberculosis
Persistent cough, afternoon fever, bloody mucus, loss of weight, fatigue and
BCG vaccination and
of the patient


Question 3.

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


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

(i) Direct contact: Person to person, animal to person and expected mother to child.

(ii) Indirect contact: Doorknob, phone, etc.

(iii) Droplet transmission: Sneezing, Coughing, etc.

(iv) Particle transmission: Air particles can transfer infectious diseases

(v) Bites and Stings: Mosquitoes, lice, ticks, etc.

(vi) Food Contamination: Food, beverages, etc.

Question 4.

Name any four non-infectious diseases and their causes.


Non-infectious Diseases Cause of the Disease
Hay fever Allergy
Cataract Degenerative (Ageing)
Beri-Beri Nutritional deficiency
Cancer Carcinogens like chemicals, tobacco smoking, pollution, etc.

Question 5.

Distinguish between:

(a) Pandemic and Sporadic diseases

(b) Communicable and non-communicable diseases

(c) Allergens and carcinogens

(d) Endemic and Epidemic diseases

(e) Pathogen and Vector


(a) Difference between pandemic and sporadic diseases :

Pandemic diseases Sporadic diseases
A pandemic disease is an outbreak of a disease that occurs over a wide geographic area and affects an exceptionally high proportion of the population. Sporadic diseases are characterized by the occurrence of isolated individual cases or occasional outbreaks of a disease.
Example: AIDS, COVID-19 Example: Malaria, Cholera

(b) Difference between communicable and non-communicable diseases :

Communicable diseases Non-communicable diseases
They are transmitted from infected person to healthy person. They are non-transmissible
They are caused by germs They are not caused by germs
Example: Cholera, Malaria. Example: Diabetes, beri-beri.

(c) Difference between allergens and carcinogens :

Allergens Carcinogens
Any agent that causes allergy is called an allergen. Any agent that causes cancer is called a carcinogen.
Allergens cause the immune system to overreact producing an allergic response. Carcinogens cause cancer by damaging DNA or interfering with cellular processes, leading to uncontrolled cell growth and the formation of tumors.
Example: Dust, Smoke, Pollen Example: Tobacco, Radiations, Pollutants

(d) Difference between endemic and epidemic diseases :

Endemic diseases Epidemic diseases
An endemic disease is found in a certain area only attacking a fewer number of people. An epidemic disease breaks out and spreads from place to place affecting large number of people at the same time.
Example: Yellow fever in African countries, Goitre in Sub-Himalayan region. Example: Plague in India in 1994, H1N1 influenza pandemic in 2009.

(e) Difference between pathogen and vector :

Pathogen Vector
A pathogen is a microorganism or agent that can cause disease in a host organism. A vector is an organism or agent that can transmit a pathogen from one host to another.
Pathogen are generally bacteria, virus, protozoa etc. Vector are generally mosquitoes, flies, rats, etc.
Example: Plasmodium, Mycobacterium tuberculosis Example: Aedes mosquito, Tsetse fly, Rats.

Question 6.

Write five important preventive measures advised by WHO to minimise the chances of getting COVID-19.


Five important preventive measures advised by WHO to minimise the chances of getting COVID-19 are:

(i) Staying at home.

(ii) Regularly washing hands with soap and water.

(iii) Avoiding crowded spaces.

(iv) Wearing a mask in public and maintaining a safe distance.

(v) Getting vaccinated.

—  : End of Diseases Cause and Control D. Long Answer Class-9 ICSE Biology Solutions :–

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