General Science Notes Chapter 16 Class 7 Maharashtra Board

Notes For All Chapters – General Science Class 7

1. Introduction

• Natural resources are materials provided by nature that humans use for survival and development.
• They include water, air, forests, minerals, fossil fuels, and sunlight.
• Some resources are renewable, while others are non-renewable.

2. Types of Natural Resources

A) Renewable Resources

✔ Resources that can be replaced naturally and do not run out easily.
✔ Examples: Sunlight, wind, forests, water, and soil.

✔ Uses of Renewable Resources:

B) Non-Renewable Resources

✔ Resources that take millions of years to form and are used faster than they can be replaced.
✔ Examples: Coal, petroleum, natural gas, and minerals.

✔ Uses of Non-Renewable Resources:

3. Forest Resources

✔ Forests are important for the environment and economy.

✔ Uses of Forests:

• Provide oxygen through photosynthesis.
• Prevent soil erosion and floods.
• Give wood for furniture, paper, and fuel.
• Home to wildlife and medicinal plants.

✔ Deforestation (Cutting Down Trees) Causes:

• Loss of animal and plant species.
• Climate change due to less oxygen and more carbon dioxide.
• Increase in soil erosion and desertification.

✔ Ways to Conserve Forests:

• Plant more trees (Afforestation and Reforestation).
• Use less paper and wood products.
• Prevent illegal cutting of trees.

4. Water Resources

✔ Water covers 71% of the Earth’s surface but only 3% is freshwater.

✔ Uses of Water:

• Drinking and cooking.
• Agriculture (irrigation).
• Industry (factories, cooling, and cleaning).
• Electricity production (hydropower).

✔ Ways to Conserve Water:

• Rainwater harvesting.
• Fixing leaks and avoiding wastage.
• Reusing water when possible.

5. Mineral Resources

✔ Minerals are natural substances found in the Earth’s crust.

✔ Two Types of Minerals:

✔ Extraction of Metals from Ores:

• Step 1: Mining – Taking minerals from the earth.
• Step 2: Purification – Removing unwanted materials to get pure metal.

✔ Conserving Minerals:

• Recycling metals like iron, copper, and aluminum.
• Using alternative materials where possible.

6. Fossil Fuels

✔ Fossil fuels are energy sources formed from dead plants and animals millions of years ago.

✔ Types of Fossil Fuels:

✔ Problems Caused by Fossil Fuels:

• Air pollution from burning fuels.
• Global warming due to carbon dioxide emissions.
• Fossil fuels are non-renewable and will run out one day.

✔ Ways to Save Fuel:

• Use public transport, cycle, or walk when possible.
• Switch to renewable energy like solar and wind power.
• Use fuel-efficient vehicles and machines.

7. Ocean Resources

✔ Oceans provide valuable resources like food, minerals, and energy.

✔ Important Ocean Resources:

✔ How to Protect Ocean Resources?

• Avoid overfishing to protect marine life.
• Reduce ocean pollution from plastic and chemicals.
• Develop eco-friendly oil extraction methods.

8. Conservation of Natural Resources

✔ Why Should We Conserve Natural Resources?

• To protect the environment and prevent shortages.
• To ensure resources are available for future generations.

✔ Ways to Conserve Natural Resources:

9. Importance of Natural Resources for the Economy

• Minerals and fuels power industries and factories.
• Forests provide wood and medicine, supporting jobs.
• Oceans support fishing, trade, and tourism.
• Agriculture depends on soil and water resources.

✔ If resources are misused, it leads to economic loss and environmental damage.