Aids to Health ICSE Class 10 Questions — Selina Chapter 13

The Aids to Health ICSE Class 10 questions in Selina Biology Chapter 13 build on one idea: the body defends itself against germs at several levels. This page explains the chapter section by section, in the book’s own order. It covers immunity, vaccination, antiseptics, antibiotics and first aid, and closes with the exercise blocks mapped to the sections they test.

Download Aids to Health Class 10 ICSE Biology Chapter 13 PDF

Download the Aids to Health Class 10 ICSE Biology chapter PDF from the Selina Concise textbook to revise offline or print for practice. It is the full chapter as printed in the book — 11 pages, 13 sections, 30 questions.

What is inside Chapter 13

11 pages · 13 sections · 30 exercise questions

• PROGRESS CHECK: 2 questions
• PROGRESS CHECK: 3 questions
• PROGRESS CHECK: 2 questions
• REVIEW QUESTIONS: 23 questions

13.1 NEED TO KEEP HEALTHY

The Aids to Health chapter opens with a two-level view of health. At the personal level, the body must be kept clean by washing, bathing and brushing teeth. Regular physical exercise, a proper diet, and adequate rest and sleep complete the personal routine.

At the community level, the surroundings must stay clean. Garbage should not accumulate, and stagnant water should not collect, because both let disease-spreading insects and pests thrive. Within the Class 10 ICSE Biology syllabus, this chapter follows the population chapter and leads into the chapter on health organisations. The syllabus is published by the CISCE.

World Health Day falls on April 7. It is celebrated to create consciousness about keeping healthy and to spread that message at all levels. The date appears in the Review Questions of this chapter.

13.2 IMMUNITY

Immunity means the body’s defence against disease, and it is the core idea of this ICSE chapter. The body is always being invaded by harmful substances, including pollutants and germs. Germs enter the body in four ways:

• directly through the skin
• through the mucous membranes of the eyes, nose, urinary or genital tracts
• through food or water intake
• through the air we breathe in

The body first tries to prevent their entry. If germs do enter, the body fights them so that they are rendered harmless. This defence works at two levels. The local defence system blocks germs at their possible entry points. The immune system deals with the germs after they have entered the body tissues.

13.2.1 Local Defence System

The local defence system has four mechanisms. The first is protective mechanical barriers. The skin has an outer tough layer made of the protein keratin, and it is almost impermeable to germs. Blood clotting plugs the cut ends of blood vessels at any wound. Hairs in the nostrils trap dust that carries germs. Mucus in the nasal passage and wind pipe traps bacteria, and the cilia of the wind pipe throw them out.

The second mechanism throws germs out if they enter. Coughing, sneezing and vomiting remove germs from the respiratory and digestive systems. Diarrhoea does the same when infection persists in the digestive tract.

The third mechanism is germ-killing secretions. Saliva, sweat, tears and nasal secretions contain germ-killing substances. Hydrochloric acid HCl in the stomach kills germs that enter with food.

The fourth mechanism is the germ-fighting white blood cells. Phagocytes squeeze out of the capillary walls by diapedesis and engulf bacteria by phagocytosis. Pus in a wound is a mixture of destroyed germs, killed white blood cells and damaged tissue cells.

Local defences have three merits. They start working instantaneously. They do not depend on previous exposure to infection. They are effective against a wide range of infectious agents.

13.2.2 Immune System

Local defences do not work in every case. Some germs and toxins enter deeper tissues through special mechanisms or through breaches in the barriers. At this stage the blood and other body fluids start fighting. They contain special proteins called antibodies, which react with the invading germs, and antitoxins, which react with their poisons.

Immunity is the body’s resistance to the onset of a disease after infection by harmful germs. More fully, it is the capacity of the body to deal with foreign substances such as bacteria, viruses and toxins, and to render them harmless. Immunity has two main kinds: innate and acquired.

Innate immunity is also called natural or native immunity. It comes from the genetic constitution of the body, with no external stimulation or previous infection. It has two forms. Non-specific innate immunity gives natural resistance to all infections in general, so humans do not catch plant diseases. Specific innate immunity resists one particular germ. For example, humans are immune to distemper, a disease of dogs that kills about 50% of infected dogs.

Acquired immunity develops during an individual’s lifetime. It may follow a previous infection, as with measles. It may also come from ready-made antibodies supplied from outside, as with anti-venin for snake-bite. Acquired immunity is active or passive.

Actively acquired immunity develops after infection or vaccination. The body’s lymphocytes produce antibodies that circulate in blood and lymph, and they also produce killer cells. Active immunity is long-lasting because it is carried by memory lymphocytes.

Passively acquired immunity is provided by ready-made antibodies from an outside source. It is natural when the mother’s antibodies reach the foetus through the placenta. It is artificial when antiserum, prepared in a horse or other animal, is injected into the patient. Anti-diphtheria injections and anti-venin work this way. Haffkine’s Institute in Bombay and an institute at Kasauli prepare several such antisera.

The differences between the two are summarised below, following the chapter’s Table 13.1.

13.2.3 Antibodies

Antibodies are special chemicals in the blood that act against germs and their secretions. They are proteins belonging to the class of immunoglobulins. Specialised lymphocytes produce them on exposure to antigens. These lymphocytes concentrate in the lymph nodes, the spleen, and the circulating blood and lymph.

Antibodies have several characteristics:

• They are specific: one kind of antibody acts against only one particular type of antigen.
• The body can make an unlimited variety of different antibodies.
• Some antibodies are present from birth, so those people do not suffer from those particular diseases.
• The immunity produced may last a short time, as in common cold and cholera, or a longer time, as in smallpox and measles.

When the immune system fails, the result is AIDS — Acquired Immuno-Deficiency Syndrome. It is caused by HIV, the Human Immunodeficiency Virus. The virus is transmitted through sexual contact, contaminated syringe needles, and blood transfusion. HIV attacks the T-cells of the thymus, which activate the lymphocytes that produce immunity. As immunity collapses, other severe infections develop unchecked. World AIDS Day is observed on December 1.

13.3 VACCINATION AND IMMUNISATION

Vaccination is the practice of introducing a preparation of weakened germs or germ substances into the body to develop resistance to a particular disease. Scientifically this practice is called prophylaxis, and the material introduced is the vaccine. Vaccines are usually given by injection and sometimes orally, as with polio drops. Inside the body, the vaccine stimulates the white blood cells to produce antibodies against that disease.

Vaccination carries its own Progress Check among the Aids to Health ICSE Class 10 questions. The chapter lists four categories of vaccines:

1. Killed germs — for example, TAB vaccine for typhoid, Salk’s vaccine for poliomyelitis, and the vaccine for rabies.
2. Living weakened germs — for example, the vaccine for measles and the freeze-dried BCG vaccine for tuberculosis. BCG stands for Bacillus of Calmette and Guerin.
3. Living fully poisonous germs — for example, the cowpox virus used for smallpox. It is no longer given because the disease has been eradicated.
4. Toxoids — inactivated toxins for diphtheria and tetanus, made harmless by adding dilute formalin.

Use a two-step pattern for any vaccine question. First identify the disease, then identify how the germ is prepared. Salk’s vaccine uses killed polio germs, so it belongs to the killed-germ category and prevents poliomyelitis. BCG uses living weakened germs and prevents tuberculosis. A diphtheria toxoid is an inactivated toxin, so it belongs to the toxoid category. This pattern fills in the vaccine table in the Review Questions.

The National Immunisation Schedule protects children and mothers on a mass scale. The age-wise programme is:

• 3-12 months: DTP (3 doses at intervals of 4-6 weeks), oral polio (3 doses), and BCG (intradermal)
• 9-15 months: measles vaccine (one dose)
• 18-24 months: DTP booster and oral polio booster
• 5-6 years: DT booster, and typhoid (TAB) vaccine in 2 doses
• 10 years: tetanus toxoid booster and typhoid booster
• 16 years: tetanus toxoid booster and typhoid booster
• Mothers during pregnancy: tetanus toxoid — one booster if previously immunised, two doses if not

DTP stands for Diphtheria, Tetanus and Pertussis (whooping cough). DT stands for Diphtheria and Tetanus.

13.4 ANTITOXINS (More appropriately called ANTIBODIES)

Toxin is a general term for any poisonous substance produced by an animal, a plant or a bacterium. Snake venom and the sting poisons of scorpions and insects are examples. Pathogens growing inside the body also release poisonous chemicals.

Antitoxin was the name given to a chemical substance produced inside the body in response to a foreign poisonous substance. Antivenins for snake-bite are produced inside animals like horses. Today the more general term antibody is used. An antibody is a blood serum protein produced in response to injected antigens.

When a patient already has a disease such as diphtheria, pre-prepared antibodies from another source help. An antibody-containing serum, called antiserum, is obtained from horses or rabbits in which the disease was produced in a mild form. Treatment with such antibodies is called passive immunisation. Haffkine’s Institute in Bombay and an institute at Kasauli prepare several such antisera.

13.5 ANTISEPTICS AND DISINFECTANTS PREVENT CATCHING DISEASES

Antiseptics and disinfectants both kill germs, but they differ in strength and in where they are applied. Antiseptics are mild chemicals used on the body. Disinfectants are strong chemicals used on spots and places where germs thrive. The chapter’s Table 13.2 sets out the difference side by side.

13.5.1 Antiseptics

Antiseptics are mild chemical substances applied on the body to kill germs. They are used in such mild concentration that they cause no harm to the skin or body. Dilute lysol, carbolic acid (phenol), iodine, benzoic acid, mercurochrome and boric acid are good antiseptics. Certain antibiotic creams serve the same purpose.

The chapter adds a caution about commercial names. Dettol, Savlon, Listerine and Soframycin are commercial names, not antiseptic names. Each product has one or more active ingredients, and it is the active ingredient that actually works. An exam answer should name the ingredient, not the brand.

• Wrong: “Dettol is an antiseptic.”
• Right: “Phenol (carbolic acid) is an antiseptic.”
• Right: “Iodine tincture is an antiseptic.”

13.5.2 Disinfectants

Disinfectants are strong chemical substances applied on spots and places where germs thrive and multiply. Cresol, phenol, lysol, 40% formalin, lime, bordeaux mixture and DDT are commonly used disinfectants.

The precaution is clear: all disinfectants are strong, and they must not come into contact with the human skin. Strong heat and boiling also destroy germs; these are called physical disinfectants.

Deodorants are neither antiseptics nor disinfectants. They only mask a bad smell. This distinction is tested directly in the Progress Check and Review Questions.

13.6 ANTIBIOTICS – PENICILLIN AND OTHERS

Antibiotics are chemical substances produced by some microorganisms that can kill or inhibit the growth of other microorganisms. Penicillin, the first antibiotic, was discovered in 1929. Its first use in treating a human disease came in the early 1940s. Selman Waksman coined the term “antibiotic” in 1942.

Alexander Fleming (1881-1955) was growing cultures of the bacterium Staphylococcus in a London hospital. In 1928 he found that an unwanted mould, Penicillium, had grown in one petri dish and had inhibited the bacteria around it. Some substance from the mould was killing the bacteria.

Fleming named it penicillin in 1929. Tests on laboratory animals gave positive results without harming the animals. On humans, penicillin was first tried in the early 1940s and worked well against several infections, especially gonorrhea.

The mould in Fleming’s discovery was Penicillium notatum, similar to the mould that grows on oranges, lemons and other citrus fruits. Commercial production largely uses P. chrysogenum. Much penicillin is now made synthetically. Streptomycin, another widely used antibiotic, is obtained from the bacterium Streptomyces.

Antibiotics have four main uses:

• fighting infections in medicine
• preserving fresh meat and fish as food preservatives
• treating animal feed to prevent internal infections
• controlling plant pathogens

Antibiotics also prevent infection after surgical operations. They work in different ways. Penicillin interferes with cell wall formation, so bacteria cannot grow and multiply. Streptomycin binds to bacterial ribosomes, stopping protein synthesis.

13.7 SULPHONAMIDE GROUP OF MEDICINES

Chemotherapy means treatment by the use of chemicals. People tried many plant and animal products over the centuries, and some chemical substances also gave good results. This approach came to be called chemotherapy.

In 1910, a drug called salvarson was produced. Based on an arsenic compound, it killed the germs of syphilis and sleeping sickness. But it frequently proved poisonous to the patient as well.

In the 1930s, a group of chemicals called sulphonamides was discovered. Sulphadiazine and sulphanilamide are two such synthetic drugs. They interfere with the metabolism of bacteria, and the bacteria are killed. Sulphonamides are now rarely used, and only in combination with antibiotics for certain ailments.

13.8 FIRST AID

Health emergencies arise suddenly. The chapter lists ten situations: serious cuts, breaking of a bone, a particle in the eye, sudden unconsciousness, a heart attack, burns, swallowing a poisonous substance, drowning, bites or stings, and electric shock. First aid is whatever must be done before the doctor arrives or the patient reaches a hospital or dispensary.

The steps for the main emergencies are:

• Bleeding: raise the affected part, wash the cut, press it with clean cotton wool, and apply a mild antiseptic.
• Fractures: lay the victim comfortably and do not move the broken part; tie a sling if the arm is fractured.
• Particle in the eye: do not rub; wash gently with clean water.
• Unconsciousness: lay the person flat, loosen the clothes, and let fresh air in.
• Heart attack: lay the person straight and horizontal, allow fresh air, and get medical help at once.
• Burns: wash with cold water for a few minutes; do not rub.
• Swallowed poison: make the patient drink salt water and induce vomiting.
• Snake bite: squeeze blood out of the wound and tie a tourniquet above the site.
• Sting: pull out the sting, squeeze out some blood, and apply an alkali such as baking soda or lime.

Artificial breathing restores breathing after drowning, electric shock or head injury. Lay the victim flat with a pillow under the shoulders so the chest is raised and the head thrown back. Hold the arms and draw them upwards and backwards; the chest expands and draws air in.

Fold the arms and press them against the ribs; the air is expelled. Repeat about 15 times per minute until the victim breathes on his own or the doctor arrives. In drowning, first lay the victim face down with the head to one side and press the back to force water out of the lungs.

The quick reference below pairs each emergency with the correct step and the common error to avoid. First aid appears in both the short answer and long answer parts of the Aids to Health ICSE Class 10 questions.

Community-level health continues in the next chapter, on health organisations.

What to practise from Aids to Health ICSE Class 10 questions

This chapter’s exercise blocks come in three Progress Checks and one set of Review Questions.

• Progress Check — 2 questions: give one example each of a germ-killing secretion, a germ-trapping secretion and a mechanical barrier, then judge six true/false statements on immunity.
• Progress Check — 3 questions: define prophylaxis, name the four categories of vaccines, and state the diseases prevented by Salk’s, BCG and DTP vaccines.
• Progress Check — 2 questions: correct seven statements (marking which are false) about antiseptics, disinfectants, antibiotics and sulphonamides, and list three uses of antibiotics.
• Review Questions — 23 questions in four parts: A (3 multiple choice), B (4 very short answer), C (10 short answer), D (6 long answer).

Most review questions map back to the chapter sections. The multiple-choice items test Section 13.6 (penicillin), Section 13.3 (DTP vaccine) and Section 13.1 (World Health Day). The very short answer questions draw on Sections 13.7, 13.6, 13.5, 13.4, 13.2.2 and 13.8. The short answer questions spread across Sections 13.5, 13.3, 13.2.2, 13.6 and 13.8. The long answers centre on vaccination (13.3), white blood cells (13.2.1), health aids (13.5 and 13.3), antibiotics (13.6) and first aid (13.8).

Aids to Health ICSE Class 10 frequently asked questions

What is the difference between active and passive immunity in class 10 biology?

Active immunity is produced by one’s own body after infection or vaccination, so it takes time to develop but is long-lasting. Passive immunity is received from outside as ready-made antibodies, so it works immediately but is less effective. Mother’s antibodies passing through the placenta give natural passive immunity; anti-venin for snake-bite gives artificial passive immunity.

Which antiseptics and disinfectants should I name in the ICSE exam?

Write the active ingredients, not the brands. For antiseptics, name iodine, benzoic acid, boric acid, mercurochrome, or dilute lysol and carbolic acid. For disinfectants, name cresol, phenol, lysol, 40% formalin, lime, bordeaux mixture or DDT. Commercial names like Dettol, Savlon, Listerine and Soframycin are not accepted as examples.

How do I remember the National Immunisation Schedule for the board exam?

Anchor the ages in pairs. The first year (3-12 months) covers DTP, oral polio and BCG. The second year adds measles at 9-15 months and boosters at 18-24 months. School-age boosters come at 5-6 years, 10 years and 16 years, with tetanus and typhoid repeated. Mothers receive tetanus toxoid during pregnancy.

Where are the Aids to Health ICSE Class 10 questions on first aid explained?

Section 13.8 of this chapter lists ten emergencies and the step for each. The pattern to remember is: raise and press for bleeding, do not move for fractures, do not rub for eye and burns, induce vomiting for swallowed poison, tie a tourniquet above the bite for snake-bite, and start artificial breathing for drowning and electric shock. The long-answer questions test several of these cases.

Why is Alexander Fleming’s penicillin discovery important for the exam?

The chapter expects the full sequence. Fleming noticed in 1928 that the mould Penicillium inhibited Staphylococcus in a petri dish, named the substance penicillin in 1929, and the first human use came in the early 1940s. Selman Waksman coined the term “antibiotic” in 1942. Questions also ask for the source (Penicillium notatum, with commercial production from P. chrysogenum) and the mechanism (interference with cell wall formation).

Reference: ICSE Class 10 Biology textbook material, chapter 13: Aids to Health — CISCE-aligned.

More from this book

• Chapter 2: Structure of Chromosomes Cell Cycle and Cell Division
• Chapter 3: Genetics Some Basic Fundamentals
• Chapter 4: Absorption By Roots the Processes Involved
• Chapter 5: Transpiration
• Chapter 6: Photosynthesis
• Chapter 7: The Circulatory System
• Chapter 8: The Excretory System
• Chapter 9: The Nervous System
• Chapter 10: Endocrine Glands
• Chapter 11: The Reproductive System
• Chapter 12: Population
• Chapter 14: Health Organisations
• Chapter 15: Pollution