Selina Concise Solutions for ICSE Class 9 Biology Chapter 17 Aids To Health

Exercise 1

Question A.1:
Answer: (c) An antibiotic
Antibiotics are powerful medicines that specifically target and kill harmful bacteria inside the body. They are essential for treating various bacterial infections that the body cannot fight off alone.
Teacher's Tip: Remember that "Anti" means against and "Bio" means life (specifically bacterial life).
Exam Tip: Do not confuse antibiotics with vaccines; antibiotics treat existing infections while vaccines prevent them.

Question A.2:
Answer: (c) Tetanus
Tetanus is a serious condition caused by bacteria entering the body through cuts or wounds. The DTP vaccine provides effective protection against this disease along with diphtheria and pertussis.
Teacher's Tip: Think of the 'T' in DTP as standing for Tetanus to remember the link.
Exam Tip: Learn the full names of diseases included in common triple vaccines like DTP.

Question A.3:
Answer: (a) April 7
World Health Day is celebrated every year on this date to draw attention to global health priorities. It marks the anniversary of the founding of the World Health Organization in 1948.
Teacher's Tip: Associate "April" with "Action" for global health to remember the month.
Exam Tip: Be precise with the date as similar-sounding dates are often provided as distractors.

Question B.1:
Answer: (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)
These terms represent specific medical breakthroughs and categories of health aids. For example, Penicillin was the first true antibiotic discovered and it changed modern medicine forever.
Teacher's Tip: "OPV" is easy to remember because it is given through the "O" (mouth) as drops.
Exam Tip: When listing examples, ensure you place the correct chemical under its specific category like "Antiseptic" or "Disinfectant."

Question B.2:
Answer: (i) Acquired Immuno Deficiency Syndrome
(ii) Bacillus Calmette Guerin
(iii) Diphtheria, Pertussis and Tetanus
(iv) World Health Organization
These full forms are critical for understanding how global health systems and immunization programs are organized. They describe specific diseases, the vaccines used to fight them, and the agencies that manage them.
Teacher's Tip: Break down long words like "Immunodeficiency" into "Immuno" and "Deficiency" to spell them easier.
Exam Tip: Capitalize the first letter of every main word in a full form to follow standard scientific naming rules.

Question B.3:
Answer: Antibodies are immunoglobulins which are produced in the blood to fight and destroy harmful microbes.
Antibodies act like the body's personal defense army, identifying and neutralizing foreign invaders. Each antibody is specially designed to recognize one specific type of germ.
Teacher's Tip: Imagine antibodies as "smart missiles" that only target the bad germs they were made for.
Exam Tip: Use the scientific term "immunoglobulins" to show a deeper understanding of the subject.

Question C.1:
Answer: (a) False. Lysol is an antiseptic.
(b) True
(c) False. Our body can make an unlimited variety of different antibodies.
(d) False. Salk’s vaccine is used against poliomyelitis.
(e) False. Treatment by the use of chemicals is known as chemotherapy.
(f) False. Selman Waksman coined the term ‘antibiotic’ for substances like penicillin.
Correcting these biological statements helps clear up common misconceptions about medicine and the body's immune system. For instance, the human body is capable of creating a unique defense for almost any new germ it encounters.
Teacher's Tip: Associate the word "Chemical" with "Chemo" to remember what chemotherapy means.
Exam Tip: If a question asks you to correct false statements, always write the full corrected sentence, not just "False."

Question C.2:
Answer: (a) Antiseptic is a mild chemical substance which is applied to the body to kill germs, whereas an antibiotic is a chemical substance produced by a microorganism which can kill or inhibit the growth of some other disease-producing microorganisms.
(b) Antiseptic is a mild chemical substance which is applied to the body to kill germs, whereas a disinfectant is a strong chemical applied to spots or places on the body where germs thrive and multiply.
(c) Disinfectant is a strong chemical applied to spots or places on the body where germs thrive and multiply, whereas deodorants are neither antiseptics nor disinfectants; they are aerosols used to mask a bad smell.
(d) Vaccination 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, whereas sterilisation 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) Active immunity is the immunity developed by an individual due to a previous infection or antigen which enters the body naturally, whereas passive immunity is the immunity provided to an individual from an outside source in the form of ‘readymade’ antibodies.
(f) Innate immunity 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, whereas 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.
These comparisons highlight the differences between immediate medical care and the long-term biological processes of the human body. Understanding these distinctions is vital for knowing how to treat a wound versus how to prevent a long-term illness.
Teacher's Tip: Remember: Antiseptics go on "Skin" (safe), while Disinfectants go on "Surfaces" (strong).
Exam Tip: Use the comparative word "whereas" to clearly show the difference between two terms in your answer.

Question C.3:
Answer: (i) TAB vaccine for typhoid
(ii) BCG vaccine for measles
(iii) DTP vaccine for diphtheria, tetanus and whooping cough
Vaccines are essential tools in public health that train the immune system to recognize and fight specific pathogens. By getting these shots, the body builds a memory of the germ so it can react quickly if ever exposed in the future.
Teacher's Tip: Link BCG with "B" (Baby) and "M" (Measles) to recall its early childhood usage.
Exam Tip: Be sure to match the specific vaccine name with all the diseases it covers, like the three parts of DTP.

Question C.4:
Answer: (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.
Identifying the "odd one out" in these groups requires knowing the specific function of every chemical and biological part. It emphasizes that while some things protect the body from the outside, others work from within the blood or cells.
Teacher's Tip: ATP is the "Energy Currency" of the cell, while DTP is a "Disease" fighter.
Exam Tip: When explaining why an item is wrong, state exactly what that item's true category or function is.

Question C.5:
Answer: Vaccine - Disease(s) - The Nature of Vaccine
TAB - 1. Typhoid - 2. Killed germs
Salk’s Vaccine - 3. Poliomyelitis - 4. Killed germs
BCG - 5. Tuberculosis - Living weakened germs
Vaccines for Measles - Measles - 6. Living weakened germs
Cowpox Virus - 7. Small pox - 8. Living fully poisonous germs
Toxoids - 9. Diphtheria - Extracts of toxins
Toxoids - 10. Tetanus - Secreted by bacteria
This summary table shows the different biological strategies used to create immunity, such as using dead germs or harmless toxins. Each type of vaccine is carefully developed to be safe for the patient while still being strong enough to train the immune system.
Teacher's Tip: Think of "Toxoids" as "Toxin-based" vaccines for diseases that produce poison.
Exam Tip: Pay attention to the "Nature of Vaccine" column as this is a high-level scientific detail often tested.

Question C.6:
Answer: 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
Immunity can be categorized into various levels based on how it is obtained and how long it lasts in the body. Some forms of protection are with us from birth, while others are developed through lifestyle or medical intervention.
Teacher's Tip: Use the words "Natural" (body does it) and "Artificial" (doctor does it) to differentiate the types.
Exam Tip: List the types in a hierarchical order starting from Innate to Acquired to show organized knowledge.

Question C.7:
Answer: 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.
Antibiotics are versatile chemical tools that benefit humans, animals, and even the food we eat. They work by blocking the vital life processes of bacteria, effectively stopping them in their tracks.
Teacher's Tip: Think of antibiotics as "microscopic biological blockers."
Exam Tip: Mentioning the "food preservative" or "animal feed" uses provides a more comprehensive answer than just medical uses.

Question C.8:
Answer: Merits of local defence systems:
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.
Local defenses, like your skin or the acid in your stomach, are your body's "front-line soldiers." They don't need instructions; they simply stop anything they don't recognize from getting deeper into the body.
Teacher's Tip: Your skin is like a "city wall" that is always standing and ready for anything.
Exam Tip: Use the word "instantaneously" to emphasize that these systems work immediately without delay.

Question C.9:
Answer: 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.
This disease primarily affects the respiratory system but can cause life-threatening complications if the bacteria's toxins reach the heart or nerves. Vaccination with the harmless toxoid is the best way to ensure the body is prepared to fight this dangerous infection.
Teacher's Tip: Remember: Diphtheria starts like a cold but can end up affecting the heart.
Exam Tip: Clearly state that the toxoid is "made harmless" before being used as a medical treatment.

Question C.10:
Answer: (a) Bleeding from a cut in the skin:
In case of bleeding, raise the affected part 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.
First aid consists of simple but life-saving actions that can be performed by anyone until professional medical help is available. These steps are designed to reduce damage, manage pain, and keep the victim's vital systems functioning.
Teacher's Tip: For breathing, remember the cycle: "Pull arms back to breathe IN, press arms in to breathe OUT."
Exam Tip: Use line breaks or bullet points to clearly list the steps for each first aid scenario.

Question D.1:
Answer: 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.
Vaccination works by "tricking" the body into thinking it has been infected so it will build up its defenses. This allows you to become immune to dangerous diseases without actually having to get sick first.
Teacher's Tip: Think of a vaccine as a "practice session" for your immune system's army.
Exam Tip: Include the word "prophylaxis" as the scientific term for preventative health practices.

Question D.2:
Answer: 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.
A high white blood cell count is like a "smoke alarm" telling doctors that there is a fire (infection) somewhere in the body. It shows that the body's internal defense system is working hard to clear out harmful invaders.
Teacher's Tip: WBCs are the "Protector cells" of your blood.
Exam Tip: Link the "multiplying of WBCs" directly to the presence of an "infection" for full marks.

Question D.3:
Answer: (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)
These three categories are the main weapons we use to manage germs in our environment and our bodies. While antiseptics and disinfectants clean up the outside world, vaccines train our inner systems for protection.
Teacher's Tip: Remember: "Disinfectant" for the "Door" (hard surfaces) and "Antiseptic" for "Achey cuts" (skin).
Exam Tip: Be ready to provide at least two examples for each of these three categories.