Science for Grade 7
1 Introduction to Science
1-1 Definition of Science
1-2 Importance of Science in Daily Life
1-3 Scientific Method
1-3 1 Observation
1-3 2 Hypothesis
1-3 3 Experimentation
1-3 4 Analysis
1-3 5 Conclusion
2 Matter and Its Properties
2-1 States of Matter
2-1 1 Solid
2-1 2 Liquid
2-1 3 Gas
2-2 Properties of Matter
2-2 1 Mass
2-2 2 Volume
2-2 3 Density
2-2 4 Solubility
2-3 Changes in Matter
2-3 1 Physical Changes
2-3 2 Chemical Changes
2-4 Mixtures and Solutions
2-4 1 Types of Mixtures
2-4 2 Separation Techniques
3 Force and Motion
3-1 Types of Forces
3-1 1 Gravitational Force
3-1 2 Frictional Force
3-1 3 Magnetic Force
3-1 4 Electrostatic Force
3-2 Motion
3-2 1 Speed and Velocity
3-2 2 Acceleration
3-2 3 Newton's Laws of Motion
3-2 3-1 First Law (Inertia)
3-2 3-2 Second Law (Force and Acceleration)
3-2 3-3 Third Law (Action and Reaction)
4 Energy
4-1 Forms of Energy
4-1 1 Kinetic Energy
4-1 2 Potential Energy
4-1 3 Thermal Energy
4-1 4 Electrical Energy
4-1 5 Light Energy
4-1 6 Sound Energy
4-2 Energy Conversion
4-2 1 Mechanical to Electrical
4-2 2 Chemical to Thermal
4-2 3 Light to Electrical
4-3 Conservation of Energy
5 Heat and Temperature
5-1 Temperature
5-1 1 Measurement of Temperature
5-1 2 Temperature Scales
5-2 Heat Transfer
5-2 1 Conduction
5-2 2 Convection
5-2 3 Radiation
5-3 Effects of Heat
5-3 1 Expansion
5-3 2 Change of State
6 Light and Sound
6-1 Light
6-1 1 Sources of Light
6-1 2 Reflection
6-1 3 Refraction
6-1 4 Lenses and Mirrors
6-2 Sound
6-2 1 Production of Sound
6-2 2 Properties of Sound
6-2 3 Reflection of Sound
6-2 4 Applications of Sound
7 Earth and Space
7-1 Earth's Structure
7-1 1 Crust
7-1 2 Mantle
7-1 3 Core
7-2 Earth's Atmosphere
7-2 1 Layers of the Atmosphere
7-2 2 Weather and Climate
7-3 Solar System
7-3 1 Planets
7-3 2 Sun
7-3 3 Moon
7-4 Space Exploration
7-4 1 Rockets
7-4 2 Satellites
7-4 3 Space Stations
8 Living Organisms and Ecosystems
8-1 Classification of Living Organisms
8-1 1 Kingdoms
8-1 2 Species
8-2 Ecosystems
8-2 1 Components of an Ecosystem
8-2 2 Food Chains and Webs
8-3 Adaptations
8-3 1 Physical Adaptations
8-3 2 Behavioral Adaptations
8-4 Human Impact on Ecosystems
8-4 1 Pollution
8-4 2 Conservation Efforts
9 Health and Nutrition
9-1 Human Body Systems
9-1 1 Circulatory System
9-1 2 Respiratory System
9-1 3 Digestive System
9-1 4 Nervous System
9-2 Nutrition
9-2 1 Essential Nutrients
9-2 2 Balanced Diet
9-3 Diseases and Prevention
9-3 1 Infectious Diseases
9-3 2 Non-infectious Diseases
9-3 3 Hygiene and Prevention
10 Environmental Science
10-1 Natural Resources
10-1 1 Renewable Resources
10-1 2 Non-renewable Resources
10-2 Pollution
10-2 1 Air Pollution
10-2 2 Water Pollution
10-2 3 Soil Pollution
10-3 Sustainable Development
10-3 1 Importance of Sustainability
10-3 2 Sustainable Practices
10-4 Climate Change
10-4 1 Causes of Climate Change
10-4 2 Effects of Climate Change
10-4 3 Mitigation Strategies
10.2.2 Water Pollution Explained

Understanding Water Pollution

Key Concepts

1. Definition of Water Pollution

Water pollution is the contamination of water bodies such as lakes, rivers, oceans, and groundwater by harmful substances, which can harm aquatic life and human health.

2. Sources of Water Pollution

Water pollution can originate from various sources, including industrial discharge, agricultural runoff, sewage, and oil spills.

3. Types of Water Pollutants

Water pollutants can be classified into several types: chemical pollutants, biological pollutants, and physical pollutants.

4. Chemical Pollutants

Chemical pollutants include heavy metals (like mercury and lead), pesticides, fertilizers, and industrial chemicals.

5. Biological Pollutants

Biological pollutants consist of pathogens such as bacteria, viruses, and parasites, often found in untreated sewage.

6. Physical Pollutants

Physical pollutants include debris, plastic waste, and oil, which can harm aquatic life and disrupt ecosystems.

7. Effects of Water Pollution

Water pollution can lead to the death of aquatic organisms, contamination of drinking water, and disruption of marine ecosystems.

8. Prevention and Control Measures

Prevention and control measures include proper waste management, sewage treatment, and the use of environmentally friendly practices in agriculture and industry.

9. Role of Government and Communities

Governments and communities play crucial roles in implementing regulations, promoting awareness, and participating in clean-up efforts.

10. Importance of Clean Water

Clean water is essential for human health, agriculture, industry, and the overall well-being of ecosystems.

Explanation of Each Concept

1. Definition of Water Pollution

Water pollution occurs when harmful substances enter water bodies, making the water unsafe for consumption and harming aquatic life.

2. Sources of Water Pollution

Industrial discharge, agricultural runoff, sewage, and oil spills are primary sources of water pollution. Industrial facilities release chemicals, farms use pesticides and fertilizers, untreated sewage contains pathogens, and oil spills introduce harmful substances into water bodies.

3. Types of Water Pollutants

Chemical pollutants can be toxic to aquatic life and humans. Biological pollutants spread diseases. Physical pollutants create hazards and disrupt ecosystems.

4. Chemical Pollutants

Heavy metals like mercury and lead can accumulate in the food chain, leading to health issues. Pesticides and fertilizers can cause eutrophication, leading to algal blooms and oxygen depletion.

5. Biological Pollutants

Pathogens in untreated sewage can cause waterborne diseases such as cholera and typhoid. Proper sewage treatment is essential to remove these harmful organisms.

6. Physical Pollutants

Debris and plastic waste can entangle and kill marine animals. Oil spills can coat water surfaces, preventing oxygen exchange and harming aquatic life.

7. Effects of Water Pollution

Water pollution can lead to the death of fish and other aquatic organisms, contamination of drinking water sources, and the disruption of marine ecosystems, affecting biodiversity and food chains.

8. Prevention and Control Measures

Proper waste management, sewage treatment plants, and the use of environmentally friendly practices in agriculture and industry can prevent water pollution. Recycling and reducing plastic use also help.

9. Role of Government and Communities

Governments implement regulations and promote awareness. Communities can participate in clean-up efforts, reduce waste, and support sustainable practices.

10. Importance of Clean Water

Clean water is vital for drinking, agriculture, and industry. It supports aquatic life and maintains healthy ecosystems, ensuring biodiversity and environmental balance.

Examples and Analogies

Example 1: Chemical Pollutants

Think of chemical pollutants like poison in a pond. Just as poison can kill fish and other creatures, chemical pollutants can harm aquatic life and contaminate water sources.

Example 2: Biological Pollutants

Biological pollutants can be compared to germs in a swimming pool. Just as germs can make people sick, pathogens in untreated sewage can cause waterborne diseases.

Analogy: Physical Pollutants

Physical pollutants are like litter in a river. Just as litter can harm wildlife and make the river look dirty, debris and plastic waste can entangle and kill marine animals and disrupt ecosystems.