ICSE Solutions for Chapter 17 Aids to Health Class 9 Biology Selina

Progress Check

1. Give one example of each of the following:

(i) Germ killing body secretion.
(ii) Germ trapping body secretion
(iii) Mechanical barrier that prevents the entry of germs into the body.


(i) Germ killing body secretion – saliva

(ii) Germ trapping body secretion – Sebum

(iii) Mechanical barrier that prevents the entry of germs into the body – Mucus

2. Mention of the following statements are True(T) or false(F)

(i) Immune system deals with the germs after they have entered the body.
(ii) Antibodies eat up the germs
(iii) Human beings can suffer from all those diseases which attack dogs
(iv) Anti-venin injection against snake bite is an example of artificially acquired passive immunity.
(v) Mother’s antibodies may reach the fetus through placenta
(vi) A person having once suffered from measles usually gets repeated attacks.


(i) True.

(ii) True.

(iii) False. Human beings are immune to a highly infectious disease of Dogs.

(iv) True.

(v) True.

(vi) False. A person having once suffered from measles will not normally suffer from it again.


3. Define the term prophylaxis.


Artificially introducing the germs or the germ substance into the body for developing resistance to a particular disease. Scientifically this process is referred to as prophylaxis.


4. Name the four categories of materials used for preparing vaccines.


The four categories of vaccines are:

(i) Killed germs
(ii) Living weakened germs
(iii) Living fully poisonous germs
(iv) Toxoids


5. Name the diseases prevented by:

(i) Salk’s vaccine
(ii) BCG vaccine
(iii) DTP vaccine


(i) Salk’s vaccine – Poliomyelitis

(ii) BCG vaccine – Tuberculosis

(iii) DTP vaccine – Pertussis(whooping cough), diphtheria, tetanus


6. Correct the following statements if they are false (without changing the first word).

(i) DDT is an antiseptic.
(ii) Penicillin is a disinfectant.
(iii) Disinfectants are applied on the body
(iv) Deodorants are both antiseptic as well as disinfectants
(v) Alexander Fleming discovered the first sulphonamide
(vi) Antibiotics cannot be made synthetically
(vii) Sulphonamides are now rarely used.


(i) DDT is a disinfectant.

(ii) Penicillin is an antibiotic.

(iii) Disinfectants cannot be applied to the body.

(iv) Deodorants are neither antiseptics nor disinfectants.

(v) Alexander Fleming discovered the first antibiotic

(vi) Antibiotics can be made synthetically.

(vii) Sulphonamides are now rarely used.


7. List any three uses of antibiotics.


The three uses of antibiotics are:

(i) They are used to fight infections.
(ii) Certain antibiotics are used as food preservatives, especially fresh meat and fish.
(iii) Some are used to control plant pathogens


Review Questions

A. Multiple Choice Type

(Select the most appropriate option in each case)

1. Penicillin is

(a) An antiseptic
(b) A disinfectant
(c) An antibiotic
(d) An anti-toxin


(c) An antibiotic
It was the first antibiotic discovered by Alexander Fleming.


2. “T” in DTP vaccination stands for

(a) Tuberculosis
(b) Typhoid
(c) Tetanus
(d) Tonsillitis


(c) Tetanus
DTP stands for Diphtheria, Tetanus and Pertussis


3. World Healthy Day is celebrated on

(a) April 7
(b) February 21
(c) October 10
(d) January 15


(a) April 7
It is celebrated to create consciousness about keeping oneself healthy and to disseminate the message at all levels.


4. DTP stands for

(a) Diphtheria, Polio and Tetanus
(b) Diphtheria, Pertussis and Tetanus
(c) Dysentery, Polio and Typhoid
(d) Diphtheria, Polio and Typhoid


(b) Diphtheria, Pertussis and Tetanus
DTP it is a vaccination used the treat Pertussis, Diphtheria and Tetanus


5. Vaccines are:

(a) An extract of toxins secreted by bacteria
(b) An extract of dead and weakened microbes
(c) Strong chemicals obtained from fungi
(d) Chemicals that are applied to the skin to kill bacteria.


(b)An extract of dead and weakened microbes
The material introduced into the body during the practice of prophylaxis is known as the vaccine


B. Very short answer type

1. Name the following:

(a) The drug based on arsenic compound, produced in 1910 which killed germs of syphilis.
(b) The antibiotic that was discovered first.
(c) The category of immunity required in the treatment of snake-bite.
(d) Any four antiseptics, any two disinfectants and any two antibiotics.
(e) The vaccines that help to produce immunity against Polio.


(a) Arsphenamine or Salvarsan

(b) Penicillin

(c) Passive acquired immunity

(d) Antiseptics - Lysol, iodine, boric acid and carbolic acid
Disinfectants - Cresol and phenol Antibiotics - Ampicillin and penicillin

(e) Oral polio vaccine (OPV)


2. Write the full forms of:

(i) AIDS
(ii) BCG
(iii) DPT vaccine
(iv) WHO
(v) HIV
(vi) ATS
(vii) TAB
(viii) STD


(i) AIDS – Acquired Immuno Deficiency Syndrome

(ii) BCG – Bacillus Calmette Guerin

(iii) DPT vaccine – Diphtheria Pertussis and Tetanus vaccine

(iv) WHO – World Health Organization

(v) HIV – Human Immunodeficiency virus

(vi) ATS – Anti Tetanus Serum

(vii) TAB – Typhoid Paratyphoid A & B

(viii) STD – Sexually Transmitted Disease


3. Give the technical term for the kind of proteins produced in the blood to fight and destroy harmful microbes.


Antibodies. They are immunoglobulins which are produced in the blood to fight and destroy harmful microbes.


C. Short Answer Type

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

(a) Lysol is an antibiotic.
(b) Sweat and tears contain germs-killing substances.
(c) Our body can make only a limited variety of different antibodies.
(d) Salk vaccine is used against tuberculosis.
(e) Treatment by the use of chemicals is known as allopathy.
(f) Alexander Fleming coined the term “antibiotic” for substances like penicillin.
(g) DDT is a disinfectant.
(h) Vaccine provides the body with Active Immunity.
(i) Penicillin was discovered by Alexander Fleming.
(j) BCG is the vaccine given to babies to help build immunity against three common diseases.


(a) False. Lysol is an antiseptic

(b) True.

(c) False. Our body can make an unlimited variety of different antibodies

(d) False. Salk vaccine is used against Poliomyelitis.

(e) False. Use of chemicals to treat is known as chemotherapy

(f) False. The term was coined by Selman Waksman.

(g) True.

(h) False. It provides the body with Passive Immunity.

(i) True.

(j) False. BCG vaccine is used for tuberculosis.


2. Differentiate between:

(a) Antiseptic and antibiotic
(b) Antiseptic and disinfectant
(c) Disinfectant and deodorant
(d) Vaccination and sterilization
(e) Active Immunity and passive immunity
(f) Innate immunity and acquired immunity


(a) Difference between Antiseptic and antibiotic



It is a mild chemical substance which is applied to the body to kill germs.

It is a chemical substance produced by a microorganism which can kill or inhibit the growth of some other disease-producing microorganisms.

(b) Difference between Antiseptic and disinfectant



It is a mild chemical substance applied to the body to kill germs

It is a strong chemical applied to spots or places on the body where germs thrive and multiply.

(c) Difference between Disinfectant and deodorant



It is a strong chemical applied to spots or places on the body where germs thrive and multiply.

They are neither antiseptics nor disinfectants; they are aerosols used to mask a bad smell.

(d) Difference between Vaccination and sterilization



It is the introduction of any kind of dead or weakened germs into the body of a living being to develop immunity (resistance) against a disease

It is a process of eliminating or killing all the microbes present on a surface, contained in a fluid, in medication or in a compound such as biological culture media.

(e) Difference between Active Immunity and passive immunity

Active Immunity

Passive immunity

It is the immunity developed by an individual due to a previous infection or antigen which enters the body naturally

Passive immunity is the immunity provided to an individual from an outside source in the form of 'readymade' antibodies.

(f) Difference between Innate immunity and acquired immunity

Innate Immunity

Acquired Immunity

It is the immunity by the virtue of genetic constitutional makeup, i.e. It is inherited from parents. It is present in the body without any external stimulation or a previous infection.

Acquired immunity is the resistance to a disease which an individual acquires during a lifetime. It may be the result of either a previous infection or from readymade antibodies supplied from outside.


3. Name any three vaccines and the diseases for which they provide immunity.


(i) TAB vaccine for typhoid
(ii) BCG vaccine for measles
(iii) DTP vaccine for diphtheria, tetanus and whooping cough


4. Given below is a table of certain vaccines, the diseases against which they are used and the nature of the vaccine. Fill up the gaps 1 – 10.



The nature of vaccine


1. _____

2. _____

Salk’s vaccine

3. ______

4. _____


5. _____

Living weakened germs

Vaccine for measles


6. _____

Cowpox virus

7. _____

8. _____



Extracts of toxins


10. ____

Secreted by bacteria




The nature of vaccine


1. Typhoid

2. Killed germs

Salk’s vaccine

3. Poliomyelitis

4. Killed germs


5. Tuberculosis

Living weakened germs

Vaccine for measles


6. Living weakened germs

Cowpox virus

7. Small pox

8. Living fully poisonous germs


9. Diphtheria

Extracts of toxins


10. Tetanus

Secreted by bacteria


5. Given below are the groups of certain substances of particular categories. Mention the category of each group and identify the wrong example giving a reason.

(a) Lysol, benzoic acid, DDT, mercurochrome.
(b) Formalin, Iodine, Lysol, Phenol
(c) BCG, DTP, ATP.
(d) Tears, Skin, Nasal Secretion, HCl (in stomach)


(a) Lysol, benzoic acid, DDT, mercurochrome Antiseptics. DDT is a wrong example for this category as it is a disinfectant which is not good for human skin.

(b) Formalin, iodine, Lysol, phenol Disinfectants. Iodine is a wrong example as it is an antiseptic.

(c) BCG, DTP, ATP Vaccines. ATP is a wrong example as it is an energy carrier in the cells of all known organisms.

(d) Tears, skin, nasal secretion, HCl (in stomach) Germ killing secretions. Skin is a wrong example as it is a protective mechanical barrier and prevents the entry of germs in our body.


6 Given below is a scheme of classifying immunity against human diseases. Fill up the types of i.mmunity in the blanks 1-9.


1 – Innate Immunity

2 – Acquired Immunity

3 – Specific Immunity

4 – Active acquired Immunity

5 – Passive acquired Immunity

6 – Natural acquired active Immunity

7 – Artificial acquired active Immunity

8 – Natural acquired passive Immunity

9 – Artificial acquired passive Immunity

7. List any four ways in which the antibiotics are being used.


Four applications of antibiotics:

  1. Antibiotics have a wide use in medicine to fight infections.
  2. Certain antibiotics are used as food preservatives, especially for fresh meat and fish.
  3. Some antibiotics are used in treating animal feed to prevent internal infection.
  4. Some antibiotics are used for controlling plant pathogens.


8. List the merits of local defence system.


Merits of the local defence system are:

  1. Local defence systems start working instantaneously.
  2. These systems are not dependent on previous exposure to infections.
  3. They are effective against a wide range of potentially infectious agents.


9. Suppose a person develops the disease diphtheria. Comment upon the principle of the treatment he should receive.


Diphtheria is a serious bacterial infectious disease. It leads to cold, coughing, sneezing and, in severe cases if undiagnosed, it might result in heart failure or paralysis.

Treatment includes a combination of medications and supportive care. The most important step is prompt intravenous administration of diphtheria toxoid which is made harmless. The harmless toxoid once administered in a patient's body triggers the production of antibodies against the pathogens causing diphtheria.


10. Write the first aid for the following:

(a) Bleeding from a cut in the skin
(b) A fractured arm
(c) Stoppage of breathing due to electrical shock


(a) Bleeding from a cut in the skin:

  • In case of bleeding, raise the affected Dart to minimise blood flow.
  • Wash the cut surface with clean water.
  • Press the area with a piece of clean cotton and apply some antiseptic.

(b) A fractured arm:

  • Lay the victim comfortably, loosen or remove the clothes from the affected part. 
  • Do not move the fractured part.
  • If the affected limb is an arm, then tie a sling around the neck to rest the arm in it.

(c) Stoppage of breathing due to electrical shock:

  • Lay the victim flat on the back and put a pillow or folded towel under the shoulders in a way that the chest is raised and the head thrown back. 
  • Hold and draw the arms upwards and backwards. This will cause the chest to expand and draw in air. 
  • Next, fold the victim's arms and press them against the ribs. The air will now be expelled. 
  • Repeat the two steps at the rate of about 15 times per minute. Continue till the victim starts breathing without any extra help or till the doctor arrives.


D. Long Answer Type

1. The principle of vaccination is to produce immunity against a disease. Explain.


  • Vaccination is the practice of artificially introducing germs or the germ substance into the body for developing resistance to particular diseases.
  • Scientifically, this practice is called prophylaxis and the material introduced into the body is called the vaccine.
  • The vaccine or germ substance is introduced into the body usually by injection and sometimes orally (e.g. polio drops).
  • Inside the body, the vaccine stimulates lymphocytes to produce antibodies against the germs for that particular disease.
  • Antibodies are an integral part of our immunity. Their function is to destroy the unwanted particles which enter the body.
  • Vaccines give our immunity a signal to produce specific antibodies. Hence, the principle of vaccination is to produce immunity against a disease.


2. Explain briefly, the role of the following health aids:

(a) Antiseptics
(b) Disinfectants
(c) Vaccines


(a) Antiseptics: Antiseptics are mild chemical substances applied to the body which prevent the growth of some bacteria and destroy others.
Examples: Lysol and iodine

(b) Disinfectants:  Disinfectants are chemicals which kill microorganisms they come in contact with. Disinfectants are usually too strong to be used on the body.
Examples: Cresol and phenol

(c) Vaccines: Vaccines are materials administered in the body to provide passive immunity. The materials are generally germs or substances secreted by germs.
Examples: OPV (oral polio vaccine) and DTP (diphtheria, tetanus and pertussis)


3. “Abnormally, large number of WBC’s in the blood are usually an indication of some infection in our body”. Comment on the statement.


Whenever a germ or infection invades the body, a signal is sent to the immune system to produce specific antibodies. To cope with the number of germs being multiplied inside the body, white blood cells start multiplying rapidly. This enables them to produce more number of antibodies and stop the infection in time. So, abnormally large numbers of WBCs in the blood are usually an indication of some infection in our body.

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