Health: The Ultimate Treasure Class 8: Healthy Living, Diseases, Vaccines and Antibiotics

What Health: The Ultimate Treasure is about

Key concepts

What health means

NCERT section 3.1 Health: Is It More Than Not Falling Sick?

The World Health Organisation (WHO) describes health as complete well-being of the body, the mind and our social life, and says that being free of disease is not enough. So health has three aspects:

• physical: the body works well;
• mental: a positive, calm mind;
• social: good relationships with family, friends and community.

A healthy person can do tasks efficiently, cope with difficult situations and get along with others.

Activity 3.1: a student who moved to a new city felt lonely, spent long hours on his phone, then had headaches, lost weight and slept badly. Less screen time and help from a counsellor in making friends improved his health: social and mental factors affect the body too.

Our scientific heritage: Ayurveda sees health as a balance of body, mind and surroundings, supported by *dinacharya* (daily routine), *ritucharya* (seasonal routine), fresh food suited to one's *prakriti* (body constitution), exercise, cleanliness, sleep, yoga and meditation.

Worked example

Riya eats well and exercises daily but has stopped talking to her friends and feels sad most days. According to the WHO definition, is she fully healthy? Explain.

Try it first, then show the solutionSolution

1. Her physical health seems good (diet and exercise).
2. But her mental and social well-being are affected (sadness, isolation).
3. Health needs all three aspects, so she is not fully healthy and may need support from family, friends or a counsellor.

Answer: No; physical health alone is not enough, her mental and social well-being also matter.

Staying healthy: lifestyle and environment

NCERT section 3.2 How Can We Stay Healthy?

Our health depends on our lifestyle (how we live) and our environment (our surroundings).

A healthy lifestyle (3.2.1):

• a balanced diet with fruits, vegetables and whole grains; avoid processed, fatty and sugary foods;
• outdoor play, walking, cycling or other exercise;
• limited screen time and more time in nature;
• enough sleep; yoga or breathing exercises (*pranayama*);
• saying 'no' to tobacco, alcohol and addictive drugs.

A clean environment (3.2.2): a clean, well-kept playground is healthier than a dirty one full of flies and mosquitoes (Activity 3.3). Smoke and dust from vehicles and factories can cause coughing or asthma; the Air Quality Index (AQI) tells us how clean the air is.

Habits to avoid (Activity 3.2): too much screen time, junk food every day, sleeping late, skipping breakfast.

Feelings and relationships matter too: spending time with friends and family, talking and laughing keep the mind healthy.

Worked example

A student spends 5 hours a day on screens instead of the 2 hours his doctor suggests. How many extra hours does he spend on screens in a week, and suggest two better uses of that time.

Try it first, then show the solutionSolution

1. Extra per day $=5-2=3$ hours.
2. Per week $=3\times 7=21$ hours.
3. Better uses: outdoor play or exercise, enough sleep, time with family and friends.

Answer: 21 extra hours a week; for example outdoor play and more sleep.

Signs and symptoms

NCERT section 3.3 How Do We Know That We Are Unwell?

When the body is not working normally, it gives clues.

• A symptom is what the person feels: pain, tiredness, dizziness, sore throat.
• A sign is something that can be seen or measured by others: fever (a high reading on a thermometer), a rash, swelling, high blood pressure.

Doctors use both, along with tests, to work out what is wrong (diagnosis).

Body response: with a cold, the body may show a raised temperature and a runny nose as it fights the infection.

Worked example

Sort these into signs and symptoms: headache, body temperature of 39 °C, red rash on the neck, feeling tired, swollen ankle, sore throat.

Try it first, then show the solutionSolution

1. Felt by the patient (symptoms): headache, feeling tired, sore throat.
2. Seen or measured (signs): temperature of 39 °C, red rash, swollen ankle.

Answer: Symptoms: headache, tiredness, sore throat. Signs: 39 °C temperature, rash, swelling.

Communicable and non-communicable diseases

NCERT section 3.4 Diseases: What Are the Causes and Types?

A disease affects the normal working of the body or mind, often when an organ or organ system stops working properly.

• Pathogens are disease-causing organisms: bacteria, viruses, fungi, protozoa and worms.
• Communicable diseases are caused by pathogens and can spread from person to person: typhoid, dengue, flu, chickenpox, COVID-19, tuberculosis.
• Non-communicable diseases (NCDs) are not caused by pathogens and do not spread between people: cancer, diabetes, asthma, high blood pressure. They are linked to lifestyle, diet and environment.
• Deficiency diseases (scurvy, anaemia, goitre) come from lacking a nutrient; they are non-communicable.
• Chronic diseases last a long time (more than 3 months), such as diabetes, asthma and cancer.

NCDs such as diabetes, heart disease and cancer have become more common in India as people eat more processed food, exercise less and live longer; most deaths in India are now caused by NCDs. Diabetes often develops from a mix of hormonal imbalance, unhealthy eating, too little activity and being overweight; its signs include frequent urination, excessive thirst, weight loss, tiredness and slow healing.

Kamal Ranadive (1917 to 2001) studied links between hormones, certain viruses and cancer, and showed how tobacco, diet and pollution raise cancer risk.

Worked example

Classify each as communicable or non-communicable and give a reason: tuberculosis, diabetes, cholera, asthma, scurvy.

Try it first, then show the solutionSolution

1. Communicable (caused by bacteria, spread between people): tuberculosis, cholera.
2. Non-communicable (not caused by pathogens): diabetes and asthma (lifestyle or environment linked), scurvy (vitamin C deficiency).

Answer: Communicable: TB, cholera. Non-communicable: diabetes, asthma, scurvy.

How communicable diseases spread, and prevention

NCERT section 3.4.1 How are communicable diseases caused and spread?

Pathogens spread in several ways:

• through air: droplets when an infected person coughs or sneezes (common cold, influenza, chickenpox, measles, tuberculosis);
• through direct contact (shaking hands) or indirect contact (sharing towels, handkerchiefs or other personal items);
• through contaminated food and water: hepatitis A (liver), cholera and typhoid (intestine), ascariasis (roundworms);
• through vectors: insects such as mosquitoes and houseflies carry pathogens; malaria (a protozoan) and dengue (a virus) spread by mosquitoes;
• some diseases spread by the bite of an infected (rabid) animal.

Worms in the intestine are parasites: they live in another living being and feed on its nutrients.

Prevention: keep yourself and surroundings clean; wash hands with soap and water; cover mouth and nose when coughing or sneezing; wear a mask in crowded places; do not share personal items; keep food and water clean and drink boiled water; use mosquito nets and repellents, wear long sleeves and stop mosquito breeding in still water; stay home when unwell; get vaccinated where vaccines exist.

Worked example

For each disease name the pathogen type and one way to prevent it: cholera, malaria, measles.

Try it first, then show the solutionSolution

1. Cholera: bacteria, spread by contaminated water and food; drink boiled water, eat properly cooked food, good sanitation (vaccination).
2. Malaria: protozoa, spread by mosquitoes; mosquito nets, repellents, stop mosquito breeding.
3. Measles: virus, spread through air; vaccination, isolating the patient, covering mouth and nose.

Answer: Cholera: bacteria (boiled water); malaria: protozoa (nets); measles: virus (vaccination).

Immunity and vaccines

NCERT section 3.5 How to Prevent and Control Diseases?

Some people fall ill more often than others in the same surroundings. The body's natural ability to fight disease is immunity, provided by the immune system.

Vaccines train the immune system to recognise and attack a particular germ, giving acquired immunity. They are made from weakened or dead pathogens, or harmless or inactive parts of them; some newer vaccines get our own cells to make a harmless part of the germ. Examples: polio drops, and injections against measles, tetanus and hepatitis. A tetanus shot after an injury contains an inactivated bacterial toxin.

• Vaccines are preventive, not curative: they protect before illness, they do not treat an illness already present.
• Vaccination protects you and the people around you, because fewer people can pass the disease on.
• On a second meeting with the same pathogen, the immune response is much stronger than the first time, because the body 'remembers' it.

Edward Jenner (late 1700s): he observed that milkmaids who had caught mild cowpox did not get smallpox, hypothesised that material from cowpox blisters protected them, tested it by giving cowpox material to a boy who later did not fall ill when exposed to smallpox, and so made the first vaccine. Mass vaccination later eradicated smallpox (by 1979). Before this, India practised variolation, done by *teekedaars*.

India is one of the world's largest vaccine producers. M.K. Bhan helped develop the rotavirus vaccine, which protects children from diarrhoea.

Worked example

Explain why a person usually does not fall seriously ill from measles if vaccinated as a child, and why the vaccine cannot be given to cure someone who already has measles.

Try it first, then show the solutionSolution

1. The vaccine (weakened or inactive germ material) trains the immune system to recognise the measles virus.
2. Later, if the real virus enters, the body responds quickly and strongly, stopping serious illness: acquired immunity.
3. Vaccines prepare the body in advance; once the disease has started, they do not treat it.

Answer: The vaccine trains the immune system in advance; it is preventive, not a cure.

Treatment: antibiotics and antibiotic resistance

NCERT section 3.5.1 Treatment of diseases

If the immune system cannot stop an infection, we need a doctor.

Antibiotics are medicines that kill bacteria (or stop their growth). They work by targeting parts of bacterial cells that are different from human and animal cells, so they work only against bacteria, not against viruses (cold, flu) or protozoa.

Discovery: in 1928 Alexander Fleming noticed that a mould on a discarded petri dish stopped bacteria from growing; the substance it released became penicillin, the first antibiotic.

Antibiotic resistance: overuse and misuse of antibiotics (taking them when not needed, for viral infections, without prescription, or stopping the course early; using them in farm animals) let a few resistant bacteria survive and multiply. Antibiotics also kill helpful bacteria, and resistant bacteria take over and can pass resistance to other bacteria. They spread through hospitals, communities, animal products, manure and crops, making common infections harder to treat. Prevention (Activity 3.7): take antibiotics only when prescribed by a doctor, in the correct dose and for the full duration.

Other treatment: traditional systems such as Ayurveda, Siddha and Unani use herbs, oils and minerals and stress lifestyle and diet; they help with some conditions but may not work for all diseases and stages. Chronic diseases are managed with medicines, lifestyle changes and rehabilitation; early diagnosis and continuous care matter.

Worked example

A doctor prescribes a 5-day antibiotic course for Arjun's bacterial throat infection. On day 3 he feels better, stops the tablets and keeps the rest "for the next time I catch a cold". Point out two mistakes in his thinking.

Try it first, then show the solutionSolution

1. Stopping early can leave the toughest bacteria alive; they multiply and may become resistant, so the infection can return and be harder to treat.
2. A cold is caused by a virus, and antibiotics act only on bacteria, so the saved tablets would not help.
3. Antibiotics should be taken only when a doctor prescribes them, in the right dose and for the full course.

Answer: He should finish the full course, and antibiotics do not work on colds (viruses).

Science in real life: Health: The Ultimate Treasure

Each concept, met in an everyday situation. Read the situation, try the problem, then check the solution. The one-line hook is what to remember.

Topics in this chapter

• Health, Pathogens and Types of Diseases
• Immunity, Vaccines and Antibiotics

Health: The Ultimate Treasure: formulas and key facts

WHO definition of health

$\text{health}=\text{physical}+\text{mental}+\text{social well-being}$

Symptom versus sign

$\text{symptom: felt by the patient};\text{sign: seen or measured}$

Types of disease

$\text{communicable (pathogens, spread)}\mid \text{non-communicable (lifestyle, diet, environment)}$

Routes of spread

$\text{air}\mid \text{contact}\mid \text{food and water}\mid \text{vectors}\mid \text{animal bite}$

Vaccines

$\text{vaccine}\to \text{trained immune system}\to \text{acquired immunity (preventive)}$

Antibiotics

$\text{antibiotics act on bacteria only; not on viruses or protozoa}$

Chronic disease

$\text{lasts more than 3 months}$

Health: The Ultimate Treasure: diagrams to practise

Practise each one on paper: draw it from the checklist, then tick off every label.

How the school exam asks Health: The Ultimate Treasure

The question patterns to expect, and the method that works for each.

Tricks to remember Health: The Ultimate Treasure

Short memory aids. Say each one aloud once, then use it on a question the same day.

• Body, Mind, Friends

  Health = Body (physical) + Mind (mental) + Friends (social).

  Use it when: WHO definition.

• You feel it, they see it

  Symptom: you feel it. Sign: they see or measure it.

  Use it when: Signs versus symptoms.

• Antibiotics are anti-bacteria

  The name tells you: anti-BIOTIC works on bacteria, not viruses.

  Use it when: When antibiotics help.

• Vaccines are a rehearsal

  A vaccine is a practice drill for the immune system before the real attack.

  Use it when: Explaining acquired immunity.

• Mosquito pair: M and D

  Malaria (protozoa) and Dengue (virus) both ride on mosquitoes.

  Use it when: Vector-borne diseases.

Health: The Ultimate Treasure: exam-level solved questions

Ordered from exam level to HOTS. Cover the solution, write your own, then compare step by step.

Case-study practice (Section E style)

Read the situation, then answer every part. In a school exam set on the board pattern this is a 4-mark question split into 1 + 1 + 2 marks.

Where the marks are

How a typical answer is split into step marks. Show every step: a right final answer alone rarely earns full marks.

Where students lose marks in Health: The Ultimate Treasure

The slips examiners see most often, and what to write instead.

• ✗Mistake: Saying antibiotics cure colds and flu

  All infections are lumped together.

  Wrong working

  Take antibiotics to recover from flu quickly.

  Right working

  Flu is caused by a virus; antibiotics act only on bacteria and should not be taken for flu.

  ✓Do this: Check the pathogen type before suggesting antibiotics.

  Usually costs: 1-2 marks.

• ✗Mistake: Calling vaccines medicines that cure

  Vaccines are given by injection like medicines.

  Wrong working

  A vaccine is given to cure a patient who has measles.

  Right working

  Vaccines are preventive: they train the immune system before infection.

  ✓Do this: Use the word 'preventive' when writing about vaccines.

  Usually costs: 1 mark.

• ✗Mistake: Mixing up signs and symptoms

  Both describe illness.

  Wrong working

  Fever is a symptom because the patient feels hot.

  Right working

  A raised temperature measured on a thermometer is a sign; feeling unwell is a symptom.

  ✓Do this: Ask: can someone else see or measure it?

  Usually costs: 1 mark.

• ✗Mistake: Treating diabetes as contagious

  Its rise in many families looks like spreading.

  Wrong working

  Diabetes spreads among family members who live together.

  Right working

  Diabetes is non-communicable; shared lifestyle and other factors may make it common in a family, but it is not caused by a pathogen.

  ✓Do this: Communicable means caused by a pathogen that passes between people.

  Usually costs: 1 mark.

• ✗Mistake: Stopping antibiotics when you feel better

  Feeling well seems to mean the infection is gone.

  Wrong working

  I felt fine after two days, so I stopped the five-day course.

  Right working

  Stopping early can leave surviving bacteria that may become resistant; finish the full prescribed course.

  ✓Do this: Correct dose, full duration, only on prescription.

  Usually costs: 1-2 marks in reasoning questions.

NCERT exercise guide: Health: The Ultimate Treasure

What each exercise in the NCERT chapter tests, how to approach it, and a question of the same kind solved step by step. Questions here are written in our own words.

Practice questions on Health: The Ultimate Treasure

Write each answer on paper first. Open the hint only if you are stuck, and the answer only when you have finished.

1. Q1 · 1 mark · MCQExam level

   Which of these is a non-communicable disease?
   (a) Cholera
   (b) Dengue
   (c) Scurvy
   (d) Tuberculosis

   Hint

   Caused by lack of a nutrient.

   Answer

   (c) Scurvy (a vitamin C deficiency disease)

2. Q2 · 1 mark · MCQExam level

   Penicillin was discovered by
   (a) Edward Jenner
   (b) Alexander Fleming
   (c) Kamal Ranadive
   (d) M.K. Bhan

   Hint

   Mould on a petri dish.

   Answer

   (b) Alexander Fleming

3. Q3 · 1 mark · Very short answerExam level

   Name the three aspects of health in the WHO definition.

   Hint

   Body, mind, society.

   Answer

   Physical, mental and social well-being.

4. Q4 · 2 marks · Very short answerExam level

   What is a parasite? Give an example from the chapter.

   Hint

   Worms.

   Answer

   An organism that lives in or on another living being and feeds on it, such as roundworms in the intestine (ascariasis).

5. Q5 · 2 marks · Very short answerHarder exam level

   Give two signs and two symptoms of diabetes from the chapter's list.

   Hint

   Some can be seen or measured.

   Answer

   Signs: weight loss, slow healing (also frequent urination can be observed). Symptoms: excessive thirst, tiredness.

6. Q6 · 3 marks · Short answerHarder exam level

   A family moves into a house next to a building site where rainwater collects in open pits. Which diseases could they be at risk of, and what three steps should they take?

   Hint

   Still water and insects.

   Answer

   Dengue and malaria, because mosquitoes breed in still water. Steps: ask for the pits to be drained, filled or covered; sleep under mosquito nets and use repellents, wearing long sleeves at dusk; see a doctor quickly if anyone gets a fever.

7. Q7 · 2 marks · Very short answerHarder exam level

   Explain why staying at home when you have flu helps others.

   Hint

   Air-borne spread.

   Answer

   Flu viruses spread through droplets in the air and through contact; staying home avoids passing them to classmates and lets your body recover.

8. Q8 · 3 marks · Short answerHarder exam level

   Describe variolation and say how it differs from Jenner's vaccine.

   Hint

   Source of the material.

   Answer

   In variolation, done in India by teekedaars, material from a smallpox sore was scratched into the skin to cause a mild infection and build immunity. Jenner instead used material from cowpox, a milder related disease, which gave protection without risking a smallpox infection.

9. Q9 · 2 marks · Very short answerHarder exam level

   Why is 'prevention is better than cure' especially true for diseases like cholera and typhoid?

   Hint

   Simple measures.

   Answer

   They can be prevented by simple steps (clean water, sanitation, hygiene, vaccination), which is easier and safer than treating an infection that causes severe diarrhoea and dehydration.

10. Q10 · 5 marks · Long answerHarder exam level

    Prepare a daily "healthy habits" chart for a Class 8 student with five habits. For each habit say whether it mainly protects against communicable or non-communicable diseases, and why.

    Hint

    Hygiene, food, activity, sleep, screens.

    Answer

    (1) Wash hands with soap before eating: communicable, removes pathogens. (2) Drink boiled or purified water: communicable, stops water-borne pathogens. (3) Eat fruit, vegetables and whole grains; cut sugary snacks: non-communicable, lowers diabetes risk. (4) Play outdoors or exercise for an hour: non-communicable, keeps weight healthy. (5) Sleep 8 to 9 hours and limit screen time: non-communicable and mental health, keeps body and mind rested.

11. Q11 · 3 marks · Short answerHOTS / competency

    Your cousin skips breakfast, sleeps after midnight and drinks cola every day, but says he is healthy because he never falls sick. Using the chapter, explain why he may be at risk.

    Hint

    WHO definition and lifestyle.

    Answer

    Health is complete physical, mental and social well-being, not just not falling sick. His habits (poor sleep, sugary drinks, irregular meals) are linked to non-communicable diseases such as diabetes, which develop slowly without obvious illness at first, and lack of sleep also affects mood and concentration.

12. Q12 · 3 marks · Short answerHOTS / competency

    A doctor says a patient's sore throat is viral but prescribes no antibiotic. The patient's relative insists on one. What should the relative understand?

    Hint

    Resistance and side effects.

    Answer

    Antibiotics do not work on viruses, so they will not help; taking them unnecessarily also kills helpful bacteria and adds to antibiotic resistance. Antibiotics should be taken only when a doctor prescribes them.

Test your recall

Answer in your head or on paper first, then open the card. Pulling an answer out of memory makes it stick far better than re-reading.

1. 1.How does the WHO define health?Show answer

   A state of complete physical, mental and social well-being, not merely the absence of disease.

2. 2.What are pathogens?Show answer

   Disease-causing organisms such as bacteria, viruses, fungi, protozoa and worms.

3. 3.Give two examples of non-communicable diseases.Show answer

   Diabetes and cancer (also asthma, high blood pressure).

4. 4.What is a vector?Show answer

   An organism such as a mosquito or housefly that carries pathogens and spreads disease.

5. 5.Name a disease caused by protozoa and how it spreads.Show answer

   Malaria, spread by mosquitoes.

6. 6.What is a chronic disease?Show answer

   A disease that lasts a long time, more than 3 months.

7. 7.What is acquired immunity?Show answer

   Protection developed after exposure to a pathogen or a vaccine.

8. 8.Who made the first vaccine, and against which disease?Show answer

   Edward Jenner, against smallpox (using cowpox).

9. 9.Who discovered penicillin and in which year?Show answer

   Alexander Fleming, in 1928.

10. 10.What is antibiotic resistance?Show answer

    When bacteria once killed by an antibiotic survive and multiply despite it.

Quick revision checklist

The night before the exam: can you do each of these without looking?

• ☐Can you state the WHO definition of health?
• ☐Can you list five healthy lifestyle habits?
• ☐Can you sort clues into signs and symptoms?
• ☐Can you classify diseases as communicable or non-communicable?
• ☐Can you name the pathogen and spread route for cholera, TB, malaria and dengue?
• ☐Can you suggest prevention for air-borne, water-borne and vector-borne diseases?
• ☐Can you explain how a vaccine gives acquired immunity?
• ☐Can you describe Jenner's investigation?
• ☐Can you explain why antibiotics do not work on viruses?
• ☐Can you explain how antibiotic resistance develops and how to prevent it?

Health: The Ultimate Treasure: frequently asked questions