Question Opening prompt 1
How does your body respond to an infection such as the common cold?
Steps only
The immune system responds to germs; symptoms vary by person and infection.
Answer
The body’s immune system works to fight the infection.
CLASS 8 · SCIENCE · CHAPTER 3
Health: The Ultimate Treasure
Simple answers to the opening prompts, chapter activities and in-text questions, all 11 end questions, and seven projects.
47 worked answersComplete chapter answers
47 worked answers · short steps first, explanations when you need them
Probe and Ponder
Textbook pages 28
Question Opening prompt 2
Why are diseases such as smallpox or polio now rarely seen in many places, while diabetes and heart disease are common?
Steps only
Vaccines and public health reduced some infections; non-communicable diseases have many risk factors.
Answer
The diseases have different causes and prevention methods.
Question Opening prompt 3
Could climate change lead to new types of diseases?
Steps only
Climate can change the habitats and seasons of some disease carriers.
Answer
It may shift disease risks, but does not automatically create new germs.
Question Opening prompt 4
How can emotions such as stress or worry affect us and make us feel unwell?
Steps only
Stress can affect mood, sleep, concentration, and how the body feels.
Answer
Mental well-being is part of health; seek support when needed.
Question Opening prompt 5
Why might some groups be affected more than others during a disease outbreak?
Steps only
Exposure, health, living conditions, and access to care can differ.
Answer
Outbreaks do not affect every group equally.
Question Opening prompt 6
Share one question you have about health or disease.
Steps only
Ask a clear question that can be explored safely with evidence.
Answer
Example: How does handwashing reduce the spread of infection?
Keep the Curiosity Alive
Textbook pages 42–45
Question Think and Reflect
A student feels lonely after moving to a new school, spends more time on social media, sleeps poorly, and develops headaches. What may be affecting the student’s health?
Steps only
Social, mental, and physical well-being are connected.
Answer
Loneliness, screen habits, and poor sleep may all be affecting the student.
Question Activity 3.7
How can antibiotic resistance develop in bacteria, and what precautions can reduce it?
Steps only
Misuse can let resistant bacteria survive and multiply; use antibiotics only as prescribed.
Answer
Use antibiotics wisely and follow a clinician’s instructions.
Question 1
Group these diseases as communicable or non-communicable: cold and flu, typhoid, diabetes, asthma, chickenpox.
Steps only
Sort diseases by whether an infectious agent can spread them.
Answer
Communicable: cold/flu, typhoid, chickenpox. Non-communicable: diabetes, asthma.
Question 2
Which option lists only non-communicable diseases? (i) Typhoid (ii) Asthma (iii) Diabetes (iv) Measles. Options: (a) i and ii (b) ii and iii (c) i and iv (d) ii and iv.
Steps only
Choose the pair that does not spread as an infection.
Answer
(b) Asthma and diabetes.
Question 3
During a flu outbreak at school: (i) What should the school do? (ii) How can you respond kindly to a benchmate with symptoms? (iii) How can everyone reduce the chance of infection?
Steps only
Use hygiene, ventilation, considerate support, and current school guidance.
Answer
Help without blaming; follow practical steps that reduce spread.
Question 4
A family is travelling to a place where malaria is common. (i) What precautions should they take before, during, and after travel? (ii) How can you explain nets or repellents to a sibling? (iii) What could happen if advisories are ignored?
Steps only
Prevent bites, check current travel advice, and report fever after travel promptly.
Answer
Nets and repellents reduce mosquito bites; they are useful precautions.
Question 5
(i) What could you say kindly to an uncle who has started smoking to fit in? (ii) What if a friend offers you a cigarette? (iii) How can schools help prevent harmful habits?
Steps only
Speak respectfully, refuse clearly, and seek support if pressured.
Answer
Kind support and health education can help prevent smoking.
Question 6
Saniya says antibiotics cure any infection. What questions could Vinita ask to help her understand why this is incorrect?
Steps only
Ask whether antibiotics work on viruses and why they should not be used unnecessarily.
Answer
Antibiotics treat some bacterial infections, not every infection.
Question 7
Dengue cases by month are: Jan 10, Feb 12, Mar 15, Apr 18, May 22, Jun 40, Jul 65, Aug 65, Sep 65, Oct 30, Nov 30, Dec 20. Draw a bar graph and answer: (i) Which three months have the highest cases? (ii) Which month has the fewest? (iii) What might contribute to the peak? (iv) How can the community or government prevent spread?
Steps only
Graph the monthly values; note the equal peak, lowest month, and possible mosquito-breeding conditions.
Answer
Highest: Jul–Sep (65 each). Lowest: Jan (10). Remove standing water and follow local guidance.
Question 8
What key messages would you include in a school campaign to reduce communicable and non-communicable diseases?
Steps only
Share messages about hygiene, vaccines, food, activity, sleep, and tobacco avoidance.
Answer
Promote healthy habits without blaming people who are ill.
Question 9
Why should antibiotics not be taken for a viral illness such as a cold, cough, or flu?
Steps only
Antibiotics do not kill viruses; unnecessary use can promote resistance.
Answer
Do not take antibiotics for a viral illness unless a clinician prescribes them for a reason.
Question 10
Which may spread if drinking water is contaminated by an infected person’s excreta: Hepatitis A, tuberculosis, poliomyelitis, cholera, chickenpox?
Steps only
Identify diseases that can spread by the faecal–oral route.
Answer
Hepatitis A, polio, and cholera.
Question Question-making activity
Prepare questions using prompts such as why, when, how long, where, and why not, based on the chapter.
Steps only
Turn chapter ideas into clear, respectful questions.
Answer
Answers vary; use reliable sources and seek professional advice for personal health.
Question 11
Why is the immune response usually stronger when the body meets the same pathogen again?
Steps only
Memory cells recognise a pathogen and help the immune system respond faster next time.
Answer
The immune system remembers some pathogens after earlier exposure or vaccination.
Discover, Design, and Debate
Textbook pages 45
Question Project 1
Keep a health diary for a month tracking food, hygiene, exercise, sleep, screen time, and emotional state.
Steps only
Record habits and mood, review weekly, and choose one small healthy goal.
Answer
Keep the diary private; it is for reflection, not diagnosis.
Question Project 2
Research Indian scientists such as Suniti Solomon, Asima Chatterjee, Yellapragada Subbarow, or Mary Poonen Lukose and describe their contributions to health.
Steps only
Pick a scientist, summarise their health-related work, and credit reliable sources.
Answer
Asima Chatterjee researched natural products and medicinal compounds.
Question Project 3
Find how vaccination helped eradicate smallpox and prepare for a respectful debate about vaccination to protect others.
Steps only
Vaccination plus surveillance and outbreak containment helped eradicate smallpox.
Answer
Smallpox was declared eradicated in 1980; discuss community protection respectfully.
Question Project 4
Learn the current adult CPR sequence and take part in a mock drill led by a doctor or trained professional.
Steps only
Learn from a qualified instructor; practise on a manikin and follow current official guidance.
Answer
Call emergency services in a real emergency; use a manikin for practice.
Question Project 5
Prepare respectful questions for a doctor about malnutrition, under-nutrition, and over-nutrition.
Steps only
Ask general questions about nutrition, growth, and respectful support.
Answer
Protect privacy and seek personal advice privately from a professional.
Question Project 6
Design a personal health card and discuss what information it should include.
Steps only
Include only useful emergency details, with family consent, and keep the card private.
Answer
A health card should protect the person’s privacy.
Question Project 7
Debate whether fast food can have harmful effects on companion animals.
Steps only
Human fast food may contain ingredients or amounts unsuitable for pets.
Answer
Feed pets species-appropriate food and ask a veterinarian about treats.
Activities and In-text Questions
Textbook pages 30–42
Question Activity 3.2
List examples of habits that support health and habits that may harm it.
Steps only
Healthy and unhealthy habits
Answer
Helpful habits include keeping clean, eating a variety of nourishing foods, being active, getting enough sleep, relaxing, and spending time with supportive people.
Question Activity 3.3
Which playground is healthier to use, and why?
Steps only
Clean surroundings
Answer
A clean, maintained playground is generally safer and more pleasant.
Question Activity 3.4
How can students compare communicable diseases and ways to reduce their spread?
Steps only
Communicable diseases
Answer
Record for each disease: its cause, how it spreads, common signs, and prevention.
Question Activity 3.5
How can a student complete a respectful survey about common long-term health conditions?
Steps only
Lifestyle and health survey
Answer
Ask a health worker or use reliable public information; do not collect classmates’ private health details.
Question Activity 3.6
What can be inferred from a community sanitation campaign that reduced open defecation and diarrhoeal illness?
Steps only
Community sanitation
Answer
Safe toilets and proper waste disposal can reduce contact with germs in human waste.
Question In-text: health
Is health only the absence of disease?
Steps only
Meaning of health
Answer
No. Health also includes physical, mental, and social well-being.
Question In-text: signs and symptoms
What is the difference between a symptom and a sign?
Steps only
Knowing when someone is unwell
Answer
A symptom is something a person feels, such as pain or tiredness.
Question In-text: causes
What is a pathogen, and are all diseases caused by pathogens?
Steps only
Diseases and pathogens
Answer
A pathogen is an organism or agent that can cause disease, such as some bacteria, viruses, fungi, or parasites.
Question In-text: spread
How can communicable diseases pass from one person to another?
Steps only
How infections spread
Answer
They may spread through air or respiratory particles, direct or indirect contact, contaminated food or water, or vectors such as mosquitoes.
Question In-text: non-communicable diseases
Are deficiency diseases communicable? What does chronic mean?
Steps only
Deficiency and chronic diseases
Answer
Deficiency diseases caused by too little of a nutrient are non-communicable; they do not spread from person to person.
Question In-text: excess nutrients
Can taking too much of a vitamin or mineral be harmful?
Steps only
Too much of a nutrient
Answer
Yes. Too much of some vitamins or minerals can cause harm.
Question In-text: body defences
What does immunity mean?
Steps only
Immunity
Answer
Immunity is the body’s ability to defend itself against infections.
Question Think like a scientist: Jenner
How did observations about cowpox help Edward Jenner develop an early smallpox vaccine?
Steps only
Jenner and vaccination
Answer
Jenner noticed that some people who had caught cowpox did not seem to catch smallpox.
Question Our scientific heritage
What was variolation, and who were teekedaars?
Steps only
Variolation and teekedaars
Answer
Variolation was an older practice intended to protect against smallpox by exposing a person to material from smallpox sores.
Question In-text: vaccines
Do vaccines treat an illness after it has started, or help prevent illness?
Steps only
What vaccines do
Answer
Vaccines train the immune system to recognise a particular germ or part of it.
Question Be a Scientist
What contribution to child health is associated with Dr Maharaj Kishan Bhan?
Steps only
Maharaj Kishan Bhan
Answer
He helped advance biotechnology and the development of an affordable rotavirus vaccine in India.
Question Think like a scientist: Fleming
What did Alexander Fleming notice that led to the discovery of penicillin?
Steps only
Fleming and penicillin
Answer
He noticed that mould growing on a laboratory dish stopped nearby bacteria from growing.
Question In-text: antibiotics
Do antibiotics work against viruses and every kind of infection?
Steps only
What antibiotics can treat
Answer
No. Antibiotics act against bacteria; they do not treat viral infections such as an ordinary cold or flu.
Question In-text: traditional care
Can traditional systems or lifestyle practices replace professional care for every disease?
Steps only
Traditional systems and disease care
Answer
No. Some traditional practices may support everyday well-being, but they are not effective for every illness or at every stage.
Question In-text: India and vaccines
Why is vaccine production important for public health?
Steps only
Vaccine production
Answer
Producing vaccines at scale can help make immunisation available to many people.