Willer Academy
Class 9 Biology - NCERT Supplement
Chapter 5: Natural Resources
Sustaining Life on Earth
Chapter 5: Natural Resources - Detailed Notes
1. Introduction to Natural Resources
Key Concept: Natural resources are materials and components found in the environment that are essential for life and human civilization.
Renewable Resources
Resources that can be replenished naturally (e.g., solar energy, wind, forests)
Non-renewable Resources
Resources that cannot be replenished in a human timescale (e.g., fossil fuels, minerals)
2. Major Natural Resources
Air (Atmosphere)
Composition: Nitrogen (78%), Oxygen (21%), Argon (0.9%), CO₂ (0.03%)
Water (Hydrosphere)
Covers 71% of Earth's surface. Only 2.5% is freshwater, mostly in glaciers
Soil (Lithosphere)
Formed by weathering of rocks. Contains minerals, organic matter, and microorganisms
Solar Energy
Primary energy source for all ecosystems. Drives photosynthesis and weather patterns
3. Biogeochemical Cycles
| Cycle | Key Processes | Significance |
|---|---|---|
| Water Cycle | Evaporation, Condensation, Precipitation | Distributes freshwater globally |
| Carbon Cycle | Photosynthesis, Respiration, Combustion | Regulates atmospheric CO₂ |
| Nitrogen Cycle | Nitrogen Fixation, Nitrification, Denitrification | Makes nitrogen available to plants |
| Oxygen Cycle | Photosynthesis, Respiration, Combustion | Maintains atmospheric O₂ levels |
Diagram: Interconnected biogeochemical cycles maintaining Earth's ecosystems
4. Threats to Natural Resources
Environmental Issues:
1. Deforestation
2. Water pollution
3. Air pollution
4. Soil erosion
5. Global warming
Human Impact: Industrialization, urbanization, and unsustainable agricultural practices are depleting natural resources and disrupting ecological balance.
5. Conservation Strategies
Afforestation
Planting trees to restore forests and prevent soil erosion
Recycling
Reusing materials to reduce waste and resource consumption
Renewable Energy
Transitioning to solar, wind, and hydro power sources
Water Conservation
Rainwater harvesting, drip irrigation, and reducing wastage
Sustainable Agriculture
Organic farming, crop rotation, and soil management
Pollution Control
Reducing emissions, treating sewage, and proper waste disposal
Sustainable Development: Meeting present needs without compromising the ability of future generations to meet their own needs.
Multiple Choice Questions (20 Questions)
Select the correct answer for each question. Each question carries 1 mark.
1. Which of the following is a renewable resource?
2. The process by which water changes from liquid to vapor is called:
3. Which gas is most abundant in the Earth's atmosphere?
4. The conversion of atmospheric nitrogen into usable compounds by bacteria is called:
Test Progress: 0/20 questions answered
Short Answer Questions (5 Questions - 2 Marks Each)
Answer these questions in 30-50 words.
1. What are the major components of air? Give their approximate percentages.
2. Explain the importance of the ozone layer for life on Earth.
3. What is soil erosion? Mention two human activities that cause it.
4. Differentiate between renewable and non-renewable resources with examples.
5. What is the greenhouse effect? Why is it important for life on Earth?
Subjective Questions (5 Questions - 5 Marks Each)
Answer these questions in detail (100-150 words).
1. Describe the water cycle with a well-labeled diagram. Explain its importance in nature.
2. Explain the carbon cycle in nature. How are human activities affecting this cycle?
3. Discuss the causes and consequences of deforestation. Suggest measures to conserve forests.
4. What is sustainable development? Explain its principles with suitable examples.
5. Describe the nitrogen cycle in nature. Why is nitrogen important for living organisms?
Performance Feedback & Ranking
Overall Performance Summary
You have completed the Chapter 5: Natural Resources test. Here's your performance analysis:
| Section | Questions | Attempted | Score |
|---|---|---|---|
| MCQ Test | 20 | 20 | 17/20 |
| Short Answer | 5 | 5 | 8/10 |
| Subjective | 5 | 5 | 22/25 |
| Total | 30 | 30 | 47/55 |
Strengths:
- Excellent understanding of biogeochemical cycles
- Strong grasp of conservation strategies
- Good knowledge of renewable vs non-renewable resources
Areas for Improvement:
- Need more practice on the nitrogen cycle details
- Review ozone layer depletion mechanisms
- Work on understanding sustainable development principles
Recommendations:
Focus on the interconnections between different natural cycles. Study the impact of human activities on each resource. Create mind maps for conservation strategies.
Your Performance Rank
Well done! Your performance is very good. You scored in the top 15% of Willer Academy students.
You have a solid understanding of natural resources and environmental science.
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