NCERT Solutions: Chapter3 Health: The Ultimate Treasure (class 8 Science)

The body responds to a common cold (caused by viruses) through the immune system[cite: 9]. Symptoms like a runny nose, sore throat, or cough occur as the body fights the infection[cite: 9]. The immune system produces antibodies to neutralize the virus, and white blood cells attack infected cells[cite: 9]. Rest, hydration, and sometimes medication (e.g., for fever) help recovery[cite: 9].

Smallpox and polio have been nearly eradicated due to widespread vaccination programs (e.g., Edward Jenner's smallpox vaccine, polio vaccines)[cite: 9]. In contrast, non-communicable diseases (NCDs) like diabetes and heart problems are increasing due to modern lifestyle factors such as unhealthy diets (e.g., processed and junk foods like pizza, burgers, etc.), lack of exercise, stress, and longer life expectancies[cite: 9].

Yes, climate change can lead to new or increased disease risks[cite: 9]. Warmer temperatures and changing weather patterns can expand the range of disease-carrying vectors like mosquitoes (e.g., malaria, dengue), alter water quality, and create conditions for new pathogens to emerge or spread more easily[cite: 9].

Stress or worry can weaken the immune system by releasing hormones like cortisol, making the body more susceptible to infections (e.g., colds)[cite: 9]. Chronic stress can also contribute to non-communicable diseases like high blood pressure or diabetes by affecting sleep, diet, and mental health[cite: 9].

Some groups are more affected due to factors like weaker immunity (e.g., children, elderly), poor living conditions (e.g., lack of sanitation), malnutrition, or preexisting health issues[cite: 9]. Social factors, such as crowded living spaces or limited healthcare access, also increase vulnerability[cite: 9].

The following habits are important for daily good health[cite: 9]:

• Eating a balanced and nutritious diet (with fruits, vegetables, and whole grains)[cite: 9].
• Maintaining personal hygiene (bathing, brushing teeth, washing hands regularly)[cite: 9].
• Exercising or being active every day and drinking clean water[cite: 9].
• Getting enough sleep every night[cite: 9].
• Spending time with family and friends for a healthy mind[cite: 9].
• Limiting screen time (phones, TV, computers)[cite: 9].
• Staying positive and managing stress (through relaxation, hobbies, or talking to someone)[cite: 9].
• Saying no to harmful substances like tobacco, alcohol, and drugs[cite: 9].

Your surroundings affect health in many ways[cite: 9]:

• Clean surroundings (at home, school, or playground) reduce germs, insects, and the chances of getting diseases[cite: 9].
• Dirty or polluted places can cause illnesses like cough, asthma, and infections[cite: 9].
• Playgrounds that are clean and safe encourage exercise and outdoor activities, which make you physically stronger[cite: 9].
• Clean water and good sanitation at home and school help prevent diseases spread by germs[cite: 9].
• People who live or study in healthy and hygienic environments feel happier, less stressed, and get sick less often[cite: 9].

Correct Answer: (b) (ii) and (iii)[cite: 9]

Explanation: The non-communicable diseases from the options are Asthma and Diabetes[cite: 9]. Typhoid and Measles are communicable diseases (spread by germs from person to person)[cite: 9]. Asthma and Diabetes are non-communicable diseases (not spread from person to person; linked to genetics, lifestyle, or environment)[cite: 9].

• (i) Immediate School Actions: The school should isolate/send home sick students, sanitise classrooms and frequently touched surfaces, encourage handwashing and mask use, and inform parents and health authorities[cite: 9]. If the outbreak is severe, temporary closure may be considered[cite: 9].
• (ii) Considerate Response to Sick Benchmate: You can politely suggest that your classmate see a doctor and take a rest at home, and offer to share notes with them[cite: 9].
• (iii) Protection Measures: To protect yourself and others, wash your hands frequently, avoid close contact, and wear a mask[cite: 9].

• (i) Travel Precautions: To protect our family from malaria during travel, focus on preventing mosquito bites and taking prescribed preventative medication[cite: 9]. Before travel, consult a doctor, get necessary vaccinations, and pack mosquito repellent and protective clothing[cite: 9]. During the trip, continue using repellent, wear long sleeves and pants, and sleep under mosquito nets[cite: 9]. After returning, monitor for any symptoms like fever, and seek immediate medical attention if they occur[cite: 9].
• (ii) Explaining to a Sibling: Explain to your sibling that mosquitoes spread malaria and that nets or repellents protect by blocking bites[cite: 9].
• (iii) Consequence of Ignoring Advisories: If travellers ignore health advisories in such areas, they risk malaria infection, severe illness, or even death[cite: 9].

• (i) Polite Conversation with Uncle: "Dear Uncle, I care about your health and well-being, and I want to talk to you about smoking[cite: 9]. It's well-known that smoking can lead to serious health issues, including heart disease and lung cancer[cite: 9]. Quitting smoking can greatly improve your health and quality of life."[cite: 9]
• (ii) Refusal Strategy with Friends: Politely decline the cigarette at the party and explain the health risks to your friend[cite: 9]. Remember: It's okay to say NO and you don't need to do something just to fit in[cite: 9].
• (iii) Role of Schools: Schools can help prevent students from indulging in such habits by educating them about the health risks and organizing awareness programs regularly[cite: 9].

Why Saniya's Statement is Wrong:

• Antibiotics only work against bacterial infections, not viral ones like the flu or common cold[cite: 9].
• Overuse or misuse of antibiotics can lead to antibiotic resistance, making them less effective in the future[cite: 9].
• Some diseases are caused by fungi, protozoa, or viruses, which require different treatments[cite: 9].

Questions Vinita can ask Saniya:
"Did you know that antibiotics don't work on viruses like the flu or measles[cite: 9]? They're only useful for bacterial infections[cite: 9]. Also, if we take antibiotics when we don't need them, they might stop working when we really do[cite: 9]. That's why doctors are careful about prescribing them."[cite: 9]

1. (i) Three Peak Months: The three months with the highest number of dengue cases are July (65 cases), August (65 cases), and September (65 cases)[cite: 9]. These are the peak months where the number of cases remained the same and were the highest for the year[cite: 9].
2. (ii) Lowest Month: The lowest number of dengue cases was reported in January (10 cases)[cite: 9]. February (12 cases) and March (15 cases) are also low, but January is the lowest[cite: 9].
3. (iii) Natural / Environmental Factors: Natural or environmental factors during the peak months, such as the rainy season and standing water for mosquito breeding, might contribute to the increase in dengue cases[cite: 9].
4. (iv) Preventive Community Measures: The community or government can take preventive steps like removing stagnant water, using mosquito nets, and spraying insecticides during this period regularly to reduce the spread of dengue[cite: 9].

Key Health Messages:

• Personal Hygiene: Wash hands with soap, keep body, clothes, and surroundings clean[cite: 9].
• Healthy Eating: Eat balanced meals with fruits, vegetables, whole grains; avoid junk food[cite: 9].
• Physical Activity: Play or exercise daily to stay fit[cite: 9].
• Prevent Disease Spread: Cover mouth/nose when sneezing or coughing, stay home when sick, avoid sharing personal items[cite: 9].
• Avoid Harmful Habits: Say no to tobacco, alcohol, and drugs[cite: 9].
• Good Sanitation: Use toilets, keep water covered, prevent mosquito breeding[cite: 9].
• Mental & Social Well-being: Share worries, manage stress, and build positive relationships[cite: 9].

The recommendation to avoid antibiotics for a viral infection like a cold, cough, or flu is because antibiotics do not work on viruses, which cause these illnesses[cite: 9]. Antibiotics target bacterial structures (such as bacterial cell walls and bacterial ribosomes) which are absent in viruses[cite: 9]. Taking antibiotics unnecessarily contributes to global antibiotic resistance[cite: 9].

The diseases that may spread if drinking water gets contaminated by the excreta from an infected person are Hepatitis A, Poliomyelitis, and Cholera[cite: 9].

(Note: Tuberculosis is spread via respiratory airborne droplets; Chickenpox is transmitted via airborne droplets or direct skin-to-skin contact with lesions.)[cite: 9]

Primary Immune Response (First Exposure):
When our body faces a pathogen (like a virus or bacteria) for the first time, our immune system needs time to[cite: 9]:

• Identify the invader[cite: 9].
• Create specific antibodies[cite: 9].
• Build memory cells that remember the pathogen[cite: 9].

This first reaction is called the primary immune response, and it's usually slow and weak[cite: 9].

Secondary Immune Response (Subsequent Exposure):
When the same pathogen enters our body again[cite: 9]:

• Our memory B cells quickly produce the correct antibodies[cite: 9].
• Our memory T cells help destroy infected cells faster[cite: 9].

This is called the secondary immune response, and it's faster, stronger, and more effective[cite: 9].

Purpose: To understand our daily health habits[cite: 9].

Record daily for a month:

• Food: What you ate (healthy/junk)[cite: 9].
• Hygiene: Bath, brushing, handwashing[cite: 9].
• Exercise: Type of activity and duration[cite: 9].
• Sleep: Bedtime, wake time, total sleep hours[cite: 9].
• Screen Time: Hours spent on phone, TV, or laptop[cite: 9].
• Mood: Happy, tired, energetic, stressed, or sad[cite: 9].

Reflection Questions: What habits make you feel good[cite: 9]? Do food, sleep, or screen time directly affect your mood[cite: 9]?

• How Smallpox Ended: People all over the world were systematically vaccinated, leaving the virus with no susceptible human hosts to spread to[cite: 9].
• Why It Worked: The vaccine conferred lifelong immunity, and the smallpox virus spread exclusively among humans without animal reservoirs[cite: 9].

Debate Summary: "Should everyone be required to get vaccinated to protect others?"

• Arguments For Mandatory Vaccination: Protects vulnerable populations (infants, cancer patients) via herd immunity; prevents epidemics; saves healthcare systems from collapse[cite: 9].
• Arguments Against Mandatory Vaccination: Personal liberty and bodily autonomy; religious or ethical convictions; concerns regarding rare adverse side effects[cite: 9].

Adult CPR Steps (as per latest international guidelines):

1. Check responsiveness: Tap shoulders and shout loudly to see if the person responds[cite: 9].
2. Call for help: Shout for immediate assistance and ask someone specific to dial emergency medical services (such as 108 in India)[cite: 9].
3. Open airway: Gently tilt the head back and lift the chin upward[cite: 9].
4. Check breathing: Look, listen, and feel for normal breathing for no more than 10 seconds[cite: 9].
5. Chest compressions: Place the heel of one hand on the center of the chest, interlock the other hand on top[cite: 9]. Push hard and fast (at least 100–120 compressions per minute)[cite: 9]. Allow the chest to recoil fully between compressions[cite: 9].
6. Rescue breaths (if trained and willing): Give 2 breaths after every 30 compressions; pinch the nose closed and seal mouth over victim's mouth[cite: 9]. If untrained, administer continuous Hands-Only CPR[cite: 9].

Recommended Interactive Discussion Points:

• What causes malnutrition or over-nutrition? Under-nutrition stems from inadequate caloric or micronutrient intake (causing stunting and anemia); over-nutrition results from excessive consumption of refined sugars, trans-fats, and ultra-processed foods (leading to childhood obesity and diabetes)[cite: 9].
• Why is breakfast important? Breakfast replenishes blood glucose levels after overnight fasting, fueling concentration and physical stamina[cite: 9].
• Which foods should we avoid? Highly processed snacks, carbonated sugary beverages, and foods high in sodium and artificial preservatives[cite: 9].
• How are food needs different for children and elders? Children require higher protein, calcium, and caloric ratios for rapid physical growth; elderly individuals require easily digestible, calcium-dense, and fiber-rich diets with moderate calories[cite: 9].

A comprehensive student health card should record vital physiological and medical data[cite: 9]:

Debate Topic: "Does human fast food harm companion pets (dogs, cats)?"

• Arguments For (Harmful Effects): Fast food contains excessive sodium, fats, and seasonings (like onions, garlic, chocolate) which are toxic to companion animals[cite: 9]. High salt and fat content causes obesity, pancreatitis, kidney damage, and gastrointestinal distress[cite: 9].
• Arguments Against (Alternative View): Small occasional tastes of unseasoned cooked plain meat do not immediately kill pets[cite: 9].
• Conclusion: Fast food is nutritionally inappropriate and harmful for companion animals; pets must be fed balanced, species-specific animal diets[cite: 9].