Class-8 Science Chapter-3

Chapter 3: Health: The Ultimate Treasure

Extracted Questions and Answers from Grade 8 Science Textbook

I. In-Chapter Questions and Activities

Probe and Ponder (Page 28)

Q1. How does your body respond to an infection such as common cold?

Ans: When infected with a common cold, the body responds with symptoms like nasal congestion, discharge, sore throat, fever, cough, and body ache. These are signs that the immune system is fighting the virus.

Q2. We rarely see cases of smallpox or polio these days, but diseases like diabetes and heart problems are more common. Why?

Ans: Smallpox and polio have been largely eradicated or controlled through mass vaccination campaigns. On the other hand, diabetes and heart problems are non-communicable lifestyle diseases that have become more common due to changes in diet (more processed/sugary food), lack of physical activity, and increased stress.

Q3. Could climate change lead to new types of diseases?

Ans: Yes, climate change can lead to new diseases or the spread of existing ones. Changes in temperature and rainfall can affect the habitats of disease-carrying vectors like mosquitoes, potentially introducing diseases to new regions.

Q4. How do emotions like stress or worry affect us and make us sick?

Ans: Emotions like stress or worry affect our mental well-being, which is closely linked to physical health. Chronic stress can weaken the immune system, lead to sleep disorders, and increase the risk of lifestyle diseases like high blood pressure and heart problems.

Q5. Why do some groups of people get affected more than others during disease outbreaks?

Ans: Factors such as living conditions (crowded or unhygienic areas), access to clean water and healthcare, nutritional status, and existing health conditions (like immunity levels) determine why some groups are more vulnerable during outbreaks.

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Activity 3.1: Think and Reflect (Page 29)

Q1. What was the cause of the boy’s health problems?

Ans: The boy's health problems were caused by loneliness, lack of social interaction after moving to a new school, and excessive screen time/social media use as a coping mechanism.

Q2. How did his habits and surroundings affect his well-being?

Ans: His habit of spending too much time on his phone led to physical symptoms like headaches, weight loss, and poor sleep. His surroundings (new city, no friends, busy parents) contributed to his mental and social isolation, affecting his overall health.

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Activity 3.2: Habits (Page 30)

Q1. List some good habits that your parents, teachers, or elders often encourage you to follow.

Ans:

• Maintaining personal hygiene (regular bathing, handwashing).
• Eating a balanced diet with fruits and vegetables.
• Exercising regularly.
• Getting enough sleep.
• Practicing meditation or relaxation.

Q2. Think about habits that are not good for your health.

Ans:

• Excessive screen time on mobile phones or computers.
• Daily consumption of junk or fast food.
• Staying up late and not getting enough sleep.
• Skipping meals, especially breakfast.

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Activity 3.3: Let us compare (Page 31)

Q1. Look at Fig. 3.3a and Fig. 3.3b. Which playground would you like to play in, and why?

Ans: Most would prefer the playground in Fig. 3.3a because it is clean, well-maintained, and beautiful. The playground in Fig. 3.3b is polluted, unhygienic, and full of flies/mosquitoes, which increases the risk of falling sick.

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Activity 3.4: Let us find out (Page 33-35)

Q1. Think about what simple steps can help prevent communicable diseases.

Ans:

• Airborne (Cold, Flu, Measles): Wash hands, cover mouth/nose when coughing, use masks, and isolate the patient.
• Water/Food-borne (Cholera, Typhoid, Hepatitis A): Drink boiled water, maintain personal hygiene, and eat properly cooked food.
• Vector-borne (Malaria, Dengue): Use mosquito nets/repellents, wear long-sleeved clothes, and prevent water stagnation.

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Activity 3.5: Let us survey (Page 36)

Q1. Find out common lifestyle-related diseases and suggested changes.

Ans:

• Obesity: Eat a balanced diet and exercise regularly.
• Diabetes: Reduce sugar intake, maintain a healthy weight, and stay active.
• High Blood Pressure: Reduce salt intake, manage stress, and avoid processed foods.

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Activity 3.6: Let us read - Odisha Case Study (Page 37)

Q1. What do you infer from this case study?

Ans: The case study shows that community-led initiatives for sanitation, such as building and using toilets, can significantly reduce open defecation and improve public health by lowering cases of diarrhea and other infections.

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Activity 3.7: Let us infer - Antibiotic Resistance (Page 41)

Q1. How do you think the antibiotic resistance has been developed in bacterial pathogens?

Ans: Antibiotic resistance develops when bacteria are exposed to antibiotics unnecessarily, in incorrect doses, or for the wrong duration. Some bacteria survive the treatment, multiply, and pass on their resistance to others.

Q2. What precautions may be taken to reduce antibiotic resistance?

Ans: Use antibiotics only when prescribed by a doctor, always complete the full course even if feeling better, and never use them for viral infections like cold or flu.

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II. End-of-Chapter Exercises (Keep the Curiosity Alive)

Q1. Group the diseases shown in the images as communicable or non-communicable: Cold and flu, Typhoid, Diabetes, Asthma, Chickenpox.

Ans:

• Communicable Diseases: Cold and flu, Typhoid, Chickenpox.
• Non-communicable Diseases: Diabetes, Asthma.

Q2. Identify the non-communicable diseases from: (i) Typhoid, (ii) Asthma, (iii) Diabetes, (iv) Measles.

Ans: The non-communicable diseases are (ii) Asthma and (iii) Diabetes. (Correct Option: b)

Q3. Flu outbreak scenario:

(i) What immediate actions should the school take?
Ans: The school should advise sick students to stay home, ensure handwashing facilities are available, and sanitize common areas.

(ii) How can you respond to a symptomatic classmate without being rude?
Ans: Politely suggest they visit the school infirmary or wear a mask to protect others, while offering to help with missed notes.

(iii) How can you protect yourself?
Ans: Wash hands frequently, avoid sharing personal items, and maintain a healthy distance from those who are sneezing or coughing.

Q4. Travel to malaria-prevalent city:

(i) Precautions before, during, and after?
Ans: Before: Consult a doctor for preventive medicine. During: Use nets and repellents, wear long clothes. After: Monitor for fever and seek medical help if symptoms appear.

(ii) Importance of mosquito nets to a sibling?
Ans: Explain that nets provide a physical barrier that prevents mosquitoes from biting while we sleep, thus preventing the transmission of malaria.

(iii) Consequences of ignoring advisories?
Ans: Ignoring advisories increases the risk of contracting serious diseases like malaria, which can lead to severe illness or even death.

Q5. Smoking scenario:

(i) How to make an uncle stop politely?
Ans: Share information about the health risks of smoking (like heart disease and cancer) and express concern for his well-being.

(ii) Refusing a cigarette at a party?
Ans: Simply say, "No thank you, I don't smoke" or "I prefer to stay healthy."

(iii) How can schools help?
Ans: Schools can organize awareness programs, workshops, and poster competitions highlighting the dangers of tobacco and other harmful substances.

Q6. Saniya’s claim: "Antibiotics can cure any infection..." What question can Vinita ask?

Ans: Vinita can ask: "Do antibiotics work against viruses that cause diseases like the common cold or flu?" (The answer is no, they only work against bacteria).

Q7. Dengue cases analysis:

(i) Highest cases months?
Ans: June, July, August, September (based on the table showing a peak in these months).

(ii) Lowest cases months?
Ans: January, February, December.

(iii) Factors for peak months?
Ans: The monsoon season (June-September) leads to water stagnation, which provides breeding grounds for mosquitoes.

(iv) Preventive steps?
Ans: Clear stagnant water, use insecticides, and conduct community awareness campaigns before the monsoon.

Q8. Health campaign messages:

• "Wash hands, stop germs!" (Communicable)
• "Eat healthy, stay active, beat diabetes!" (Non-communicable)
• "Clean surroundings, healthy life!" (General)

Q9. Why not take antibiotics for viral infections like cold/flu?

Ans: Antibiotics are designed to target specific parts of bacterial cells. They do not have any effect on viruses. Taking them unnecessarily can lead to antibiotic resistance.

Q10. Disease spread by contaminated water from excreta?

Ans: Hepatitis A, Poliomyelitis, and Cholera.

Q11. Why is the immune response stronger on second exposure?

Ans: On the first exposure, the immune system learns to recognize the pathogen. It creates 'memory cells' that stay in the body. Upon second exposure, these cells recognize the pathogen immediately and produce a faster, stronger response.