CBSE Class 8 Science Notes Chapter 12 How Nature Works in Harmony

Preparing for school exams becomes much easier when you have concise notes that cover all the important concepts in one place.

These CBSE Class 8 Science Chapter 12 Notes – How Nature Works in Harmony are designed to help you revise the entire chapter quickly without going through lengthy textbook explanations.

The notes below explain key topics such as habitats, ecosystems, food chains, food webs, trophic levels, decomposition, biological relationships, and sustainable farming in simple points. Whether you're preparing for a class test, annual examination, or quick revision, these notes can help you strengthen your understanding of the chapter.

CBSE Class 8 Science Chapter 12 Notes – How Nature Works in Harmony

Understanding the concepts in Chapter 12 can become difficult if you revise only from the textbook before your exams. These CBSE Class 8 Science Notes Chapter 12 – How Nature Works in Harmony help you revise every important topic in a simple, point-wise format, making it easier to understand key concepts and prepare confidently for your school examinations.

1. Habitat

• A habitat is the place where an organism lives.

• It provides food, water, air, shelter, and suitable living conditions.

Examples:

• Forest

• Pond

• Lake

• River

• Farm

• Tree

2. Components of a Habitat

Every habitat is made up of living and non-living components that work together to support the survival of organisms.

(a) Biotic Components

These are the living components of a habitat.

• Plants

• Animals

• Microorganisms

(b) Abiotic Components

These are the non-living components of a habitat.

• Air

• Water

• Soil

• Sunlight

• Temperature

3. Population

A population refers to a group of organisms of the same species living together in a particular habitat.

• A population is a group of the same kind of organisms living in a habitat at a particular time.

Example: All fish living in a pond.

4. Community

A community is formed when different populations of plants, animals, and microorganisms live and interact within the same habitat.

• A community consists of different populations living together.

• It includes plants, animals, and microorganisms interacting with one another.

5. Ecosystem

An ecosystem is formed by the interaction between living organisms and their non-living surroundings.

• An ecosystem is formed through interactions between living (biotic) and non-living (abiotic) components.

• It provides food, shelter, and maintains ecological balance.

Types of Ecosystems

Terrestrial Ecosystems

• Forest

• Grassland

• Desert

Aquatic Ecosystems

• Pond

• Lake

• River

Human-made Ecosystems

• Farms

• Gardens

• Fish ponds

6. Interactions in an Ecosystem

Different living and non-living components interact with one another to keep an ecosystem balanced and functioning properly.

Biotic–Abiotic Interaction

• Plants use sunlight, water, and carbon dioxide to prepare food through photosynthesis.

Biotic–Biotic Interaction

• Animals depend on plants or other animals for food.

Abiotic–Abiotic Interaction

• Sunlight affects temperature and evaporation.

7. Producers, Consumers, and Decomposers

Producers, consumers, and decomposers work together to ensure the continuous flow of energy and recycling of nutrients in an ecosystem.

Producers

• Green plants prepare their own food through photosynthesis.

Consumers

Herbivores: Eat plants (Example: Deer)

Carnivores: Eat animals (Example: Tiger)

Omnivores: Eat both plants and animals (Examples: Fox, Crow)

Decomposers

• Bacteria and fungi break down dead plants and animals.

• They recycle nutrients back into the soil.

8. Food Chain

• A food chain shows the sequence of "who eats whom."

Example:

Grass → Grasshopper → Frog → Snake

9. Trophic Levels

Each step in a food chain is called a trophic level.

• 1st Trophic Level: Producers

• 2nd Trophic Level: Herbivores

• 3rd and Higher Levels: Carnivores

10. Food Web

• A food web is a network of interconnected food chains.

• It makes an ecosystem more stable.

11. Decomposition

• Decomposition is the breakdown of dead plants and animals by decomposers.

• It returns nutrients to the soil.

• It ensures that nothing in nature goes to waste.

12. Balance in an Ecosystem

The balance of an ecosystem is maintained through:

• Feeding relationships

• Competition

• Decomposition

Any disturbance in this balance can cause chain reactions throughout the ecosystem.

13. Types of Biological Relationships

Organisms in an ecosystem interact with one another in different ways, leading to various types of biological relationships.

Mutualism

• Both organisms benefit.

Example: Bee and Flower

Commensalism

• One organism benefits while the other is neither helped nor harmed.

Example: Orchid growing on a tree

Parasitism

• One organism benefits while the other is harmed.

Example: Tick on a dog

14. Human Impact on Ecosystems

Human activities can disturb ecological balance.

Examples include:

• Deforestation

• Pollution

• Overfishing

Example:

A decline in frog populations may lead to an increase in insects, resulting in greater use of pesticides.

15. Benefits of Ecosystems

Ecosystems provide:

• Clean air

• Water

• Food

• Medicines

• Climate regulation

They play an essential role in supporting human life and maintaining biodiversity.

16. Sundarbans Ecosystem

• The Sundarbans is the largest mangrove forest in the world.

• It protects nearby regions from floods and storms.

• It is threatened by deforestation, pollution, and hunting.

17. Sustainable Farming

Excessive use of fertilizers and pesticides damages soil quality.

Sustainable farming practices include:

• Organic manure

• Crop diversity

• Natural pest control

These methods help maintain soil fertility and protect the environment.

Download CBSE Class 8 Science Chapter 12 Notes PDF

Download the CBSE Class 8 Science Chapter 12 Notes PDF to access the complete chapter in one place. You can use the PDF for offline study, quick revision, and convenient preparation anytime before your exams.

Benefits of CBSE Class 8 Science Chapter 12 Notes 

Using well-organised chapter notes makes your revision faster and more effective. These notes help you understand important concepts, remember key points, and prepare confidently for class tests and annual examinations.

Benefits:

• Quickly revise the complete chapter in less time.

• Understand important concepts through simple, point-wise explanations.

• Easily remember definitions, examples, and scientific terms.

• Identify key topics frequently asked in school exams.

• Improve your last-minute revision before tests and annual examinations.

• Access the PDF anytime for offline study and revision.