Class 8 Science Chapter 3 Health: The Ultimate Treasure (New Course)

Key Concept: Communicable Diseases: Prevention

d) Control of mosquito breeding in and around homes
[Solution Description]
Dengue fever is transmitted by Aedes mosquitoes, which breed in stagnant water. Controlling mosquito breeding sites, such as removing standing water, is the most effective prevention method. Washing hands helps prevent other diseases but not dengue specifically.

Key Concept: Antibiotics, Antibiotic Resistance

c) Development of antibiotic-resistant bacterial strains
[Solution Description]
When antibiotics are not taken for the full prescribed duration, some bacteria may survive and develop resistance to that antibiotic. These resistant bacteria can then multiply and spread to others, making future infections harder to treat. This contributes to the global problem of antibiotic resistance.

Key Concept: Exercise, Stress management

d) Brisk walking in a natural park setting
[Solution Description]
This combines exercise and stress management aspects.
Step 1: We need an activity that involves physical movement (exercise) while also reducing stress.
Step 2: Playing competitive sports may increase stress due to performance pressure.
Step 3: Watching TV is sedentary and doesn’t relieve stress effectively.
Step 4: Cycling combines cardiovascular exercise with rhythmic movement that reduces stress hormones.
Step 5: Brisk walking in nature provides exercise and the calming effects of natural surroundings.
Between the two best options (cycling and brisk walking in nature), brisk walking is more consistently recognized for dual benefits in health guidelines.

Key Concept: Disease Control, Community Campaigns, Government Collaboration

c) It combines government resources with community participation for sustainable outcomes.
[Solution Description]
Government support provides resources and policy frameworks, while community involvement ensures local adoption and sustainability. Together, they create effective and lasting public health improvements.

Key Concept: Mental health, Lifestyle factors, Non-communicable diseases

c) Daily 30-minute cardio, 7-hour sleep routine, and meditation
[Solution Description]
Chronic stress from overwork causes hypertension and sleep disorders. Effective management requires: 1) Regular aerobic exercise lowers BP and improves sleep quality, 2) Consistent sleep schedule regulates circadian rhythm, 3) Mindfulness reduces stress hormones, 4) Limiting caffeine/alcohol prevents sleep disruption and BP spikes.

Key Concept: Non-Communicable Diseases, Lifestyle Factors

d) Eating balanced meals and exercising regularly.
[Solution Description]
Non-communicable diseases are primarily caused by unhealthy lifestyle choices such as poor diet, lack of physical activity, and smoking. Adopting healthy habits like eating balanced meals, exercising regularly, and avoiding tobacco can significantly reduce the risk of these diseases. Unlike communicable diseases, they cannot be prevented by vaccines or hygiene alone.

Key Concept: Physical, Mental, Social Health

d) Mental and social health
[Solution Description]
The WHO defines health as a state of complete physical, mental, and social well-being. In this case:
1) Physical health: While tiredness and sleep issues are present, they stem from other factors.
2) Mental health: Anxiety indicates mental distress.
3) Social health: Struggling with social interactions shows impaired social well-being.
The primary issue is the combination of mental anxiety and social struggles, making ‘Mental and Social Health’ the best answer.

Key Concept: Diabetes, Lifestyle Factors

c) Development of Type 2 diabetes
[Solution Description]
The individual’s high BMI, unhealthy diet, and lack of physical activity are key risk factors for Type 2 diabetes. Obesity and sedentary lifestyle contribute to insulin resistance, leading to elevated blood sugar levels over time. Prevention strategies include adopting a balanced diet and regular exercise.

Key Concept: Role of Teekedaars

c) Traditional healers called teekedaars
[Solution Description]
In India, individuals known as teekedaars performed variolation, the traditional method of preventing smallpox by introducing material from smallpox sores into the skin to induce mild infection and immunity.

Key Concept: Symptom-Sign Differentiation, Real-World Application

b) Fever of $40^\circ$C and swollen lymph nodes
[Solution Description]
Signs are measurable/observable indicators. Immediate attention is needed for severe signs like high fever ($>39^\circ$C), rapid heart rate, or swelling. Symptoms (e.g., nausea) alone may not warrant urgency. The correct answer must prioritize measurable signs indicating severity.

Key Concept: Symptoms, Vector-borne Diseases

c) Dengue fever
[Solution Description]
The symptoms—fever, headache, muscle and joint pain, and nausea—are indicative of dengue fever. Dengue is a viral disease transmitted by Aedes mosquitoes, which breed in stagnant water. It is commonly referred to as “breakbone fever” due to the severe muscle and joint pain it causes.

Key Concept: Disease prevention, Airborne diseases

c) Covering mouth and nose properly
[Solution Description]
Both measles and chickenpox are airborne diseases (from respiratory tract) according to Table 3.1. The common preventive measures listed for both include isolation of patients and covering mouth/nose (respiratory hygiene). While vaccination is mentioned, it’s disease-specific, whereas respiratory hygiene applies to both equally.

Key Concept: Vaccine Types, Immune System

c) Live-attenuated virus vaccine
[Solution Description]
Live-attenuated vaccines contain weakened forms of the live virus that can’t cause disease but can still replicate in the body. This replication mimics a natural infection, stimulating both cell-mediated and antibody-mediated immunity, resulting in strong and long-lasting immune protection. Inactivated vaccines (killed pathogens) and subunit vaccines (using parts of pathogens) typically require booster shots as they don’t replicate and provide shorter-term immunity. DNA vaccines are still experimental for most diseases.

Key Concept: Tree Plantation, Air Pollution

c) Trees absorb carbon dioxide and release oxygen
[Solution Description]
Trees absorb carbon dioxide and release oxygen through photosynthesis, improving air quality. They also trap particulate matter on their leaves, acting as natural filters. The other options describe secondary or unrelated effects of trees.

Key Concept: Signs vs Symptoms, Fever, Rash

c) Feeling extremely tired and dizzy
[Solution Description]
The question distinguishes between symptoms (what the patient feels) and signs (what can be measured or observed). Here, the patient reports feeling tired and dizzy (symptoms), while the doctor measures fever and observes rash (signs). Thus, the correct answer is what the patient felt.

Key Concept: Symptoms, Signs, Differential Diagnosis

c) Chest pain = symptom, Elevated heart rate = sign
[Solution Description]
Chest pain is a subjective experience reported by the patient, qualifying as a symptom. An elevated heart rate (110 bpm) is measurable data, qualifying as a sign. Thus, the correct pairing is: chest pain = symptom, elevated heart rate = sign.

Key Concept: Clean vs. Polluted Environment

b) It is clean, well-maintained, and hygienic.
[Solution Description]
A clean playground is well-maintained, free from pollution, and hygienic, reducing health risks. It looks beautiful and does not attract flies or mosquitoes, making it safer and more pleasant for play.

Key Concept: Vaccine development, eradication of smallpox

c) Mass vaccination eliminated human hosts, leaving no reservoir for the virus.
[Solution Description]
Mass vaccination created herd immunity, reducing the number of susceptible individuals and breaking the chain of transmission. Smallpox only infects humans, so widespread vaccination eliminated its reservoirs, making global eradication possible. The last natural case was reported in 1977, and eradication was declared in 1980.

Key Concept: Chronic diseases, Asthma triggers

b) Exposure to cold air
[Solution Description]
Cold air is a common trigger for asthma attacks as it can cause airways to constrict. During winter, exposure to cold air increases, leading to more frequent asthma symptoms in affected individuals.

Key Concept: Physical activity, Screen time, Ayurvedic principles

b) Following dinacharya with yoga, fresh meals, and early sleep
[Solution Description]
Ayurveda emphasizes dinacharya (daily routine) with wholesome food, exercise, adequate sleep, and mindfulness. Reducing screen time prevents mental strain, while seasonal adjustments (ritucharya) adapt routines for holistic health.

Key Concept: WHO Definition of Health

c) Complete physical, mental, and social well-being
[Solution Description]
The WHO defines health as a state of complete physical, mental, and social well-being, not merely the absence of disease. This means a healthy individual must have good physical condition, positive mental health, and strong social relationships.

Key Concept: Hygiene, Multi-Concept Application

b) Wearing a mask, washing hands after handling food, and avoiding shared utensils.
[Solution Description]
The syllabus emphasizes multi-layered hygiene: handwashing, mask-wearing in crowds, and avoiding shared items. Option (b) combines these three key strategies, whereas other options omit at least one critical measure (e.g., no handwashing or mask usage).

Key Concept: Definition of Health

c) A balanced state of body, mind, and surroundings
[Solution Description]
According to Ayurveda, health is defined as a balance of body, mind, and surroundings, not just the absence of disease but a state of complete well-being.

Key Concept: Penicillin Discovery, Scientific Methodology

c) Accidental observations can lead to important discoveries
[Solution Description]
Fleming’s discovery showed how careful observation of unexpected results (the mold killing bacteria) can lead to major scientific breakthroughs. This demonstrates the importance of serendipity and astute observation in science.