Welcome to our comprehensive guide on the NCERT Solutions for Class 9 Social Science Part 2 Chapter 2: Life on Earth. This chapter, part of the newly released Understanding Society: India and Beyond (Part 2) textbook, explores the incredible diversity of biomes, the ecological significance of forests, and the vital role of traditional conservation methods in protecting our biosphere.
Below, you will find meticulously crafted, accurate answers to all 9 questions presented in the textbook exercises. These solutions are formulated to help you grasp the core environmental concepts effectively and score maximum marks in your examinations.
End-of-Chapter Exercises: Life on Earth
1. Why does India have diverse biomes? How does the local geography connect to the diversity?
Answer:
India possesses diverse biomes because of its vast range of physical features, latitude, altitude, and climatic patterns:
Varied Relief and Landforms: India encompasses high mountain ranges (Himalayas), extensive plateaus, fertile river valleys, coastal plains, and island archipelagos. High altitudes support coniferous forests and alpine vegetation, while low-lying tropical regions support dense rainforests.
Precipitation and Temperature Variation: The country experiences diverse rainfall gradients, from extremely high precipitation in the Northeast and Western Ghats (supporting tropical rainforests) to semi-arid and arid zones in the northwest (supporting the Thar desert and salt deserts like the Rann of Kutch).
Latitudinal Span: Spanning from tropical latitudes in the south to subtropical and temperate belts in the north, temperature ranges directly govern growing seasons and the types of plants and animals that thrive in each region.
2. Make a list of economically valuable native plants in your region and comment on their abundance.
Answer:
(Example based on central Indian deciduous forest ecosystems):
Tendu (Diospyros melanoxylon): Moderately abundant; widely collected for its leaves, which provide seasonal wage labor and household income for rural and tribal communities.
Mahua (Madhuca longifolia): Abundant; the flowers and seeds are harvested for food, oil, and local market trade.
Sal (Shorea robusta): Common to abundant across dry and moist deciduous zones; valued for structural timber, resin, and seeds.
Bamboo (Bambusoideae): Extensively distributed; used in rural construction, basket weaving, and cottage craft industries.
Neem (Azadirachta indica): Highly abundant in both cultivated and wild landscapes; used widely for traditional medicinal and pest-control applications.
3. Prepare a map of your state or Union Territory showing national parks and sanctuaries.
Answer:
(To complete this activity for your state map:)
Draw or trace the political outline of your home state or Union Territory.
Mark key Protected Areas: Locate and label official National Parks and Wildlife Sanctuaries (e.g., Kanha, Bandhavgarh, and Pench for Madhya Pradesh; Jim Corbett and Rajaji for Uttarakhand; or Kaziranga and Manas for Assam).
Add an Index/Legend: Use distinct symbols (such as solid green triangles for National Parks and green squares for Wildlife Sanctuaries) along with a compass rose indicating North.
4. Study the impact of forest fires on people dependent on forests (causes, losses, and preventive measures).
Answer:
Causes:
Natural: Extreme heatwaves, extended droughts, and lightning strikes.
Human-Induced: Careless disposal of burning matchsticks/beedis, unattended campfires, and intentional burning of dry ground litter for clearing land or collecting non-timber produce.
Losses:
Destruction of non-timber forest resources (honey, resins, medicinal plants, fuelwood), which causes direct livelihood and income losses for forest dwellers.
Severe air pollution and smoke, leading to respiratory and eye ailments among local inhabitants.
Destruction of wildlife habitats, livestock fodder, and traditional dwellings near forest fringes.
Preventive Measures:
Construction and maintenance of cleared forest fire lines to halt surface fire propagation.
Active community vigilance and Joint Forest Management (JFM) fire-watch patrols.
Controlled, early-season winter burning of leaf litter under administrative supervision to reduce dry fuel loads.
5. Why are forests often called the ‘lungs of the Earth’?
Answer:
Forests are referred to as the ‘lungs of the Earth’ because they continuously carry out photosynthesis, during which vast amounts of carbon dioxide are absorbed and oxygen is released back into the atmosphere. This gas exchange maintains global oxygen levels and helps regulate the Earth’s climate.
6. If large forest areas continue to be destroyed, what do you think would be its long-term effect on the global climate?
Answer:
Accelerated Global Warming: Massive loss of carbon sinks increases atmospheric CO₂, amplifying the greenhouse effect and accelerating climate change.
Disrupted Hydrological Cycles: Widespread tree loss reduces local transpiration, leading to erratic monsoon patterns, decreased regional rainfall, and prolonged droughts.
Severe Land Degradation: Removal of tree canopy and root systems accelerates topsoil erosion, triggers landslides in hilly terrains, and causes heavy siltation and flash flooding in downstream rivers.
7. Traditional forest conservation methods to discuss with elders
Answer:
Sacred Groves (Devrai, Sarna, Devarakadu, Kavu): Protected communal forest patches where felling trees and hunting are prohibited due to spiritual and customary rules, preserving virgin flora and rare medicinal herbs.
Ritualized Resource Harvesting: Customary practices (such as those observed by Gond and Bhil communities) where nature deities are honored before harvesting, ensuring seeds and rootstocks are preserved for natural regeneration.
Community-Regulated Grazing and Gathering: Rotational grazing schedules and selective felling rules enforced by village councils to avoid depleting common property resources.
8. How do forest dwellers contribute to the protection and conservation of forests?
Answer:
Traditional Ecological Knowledge: Passing down deep hereditary understanding of local biodiversity, plant reproductive cycles, and non-destructive harvesting methods across generations.
Grassroots Environmental Movements: Historical and contemporary leadership in defending forests against commercial overexploitation (such as Amrita Devi’s Bishnoi movement and the Chipko movement).
Community Self-Governance: Enforcing local rules through community assemblies (Gram Sabhas), monitoring forests against illegal timber logging, and managing controlled bamboo harvesting (exemplified by the Mendha Lekha model).
9. What is a forest fire, and what are measures for the mitigation of forest fires?
Answer:
Definition: An uncontrolled fire occurring in combustible forest vegetation and wildlands, driven by dry biomass, high temperatures, low humidity, and wind.
Mitigation Measures:
Early Detection and Monitoring: Using satellite systems and regional geoportals (such as the School Bhuvan-NCERT Geoportal) for near-real-time thermal spot detection.
Physical Firebreaks: Clearing linear swathes of vegetation along ridges and compartment boundaries to isolate potential fires.
Community-Led Preparedness: Training forest communities in rapid ground response, fire-beating methods, and preventing uncontrolled open burning during high-risk seasons.
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