Our Environment Class 10 Notes: Simplified and Explained

Embark on a journey to become an eco-warrior with our comprehensive and simplified guide to Our Environment, Chapter 13 of Class 10 Science (NCERT). Designed specifically for students preparing for the CBSE 2023-24 board exams, these notes provide a clear and concise understanding of this crucial topic.

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Subject	Science
Class	10
Board	CBSE & State Boards
Chapter No.	13
Chapter Name	Our Environment
Type	Notes
Session	2023-24

"The way to get started is to quit talking and begin doing."

- Walt Disney

Our Environment Class 10 Notes

EcoSystem - What are its Components?

Ecosystem: All the interacting organisms in an area together with the non-living constituents of the environment form an ecosystem.

An ecosystem consists of

• biotic components comprising living organisms
• abiotic components comprising physical factors like temperature, rainfall, wind, soil, and animals.

Types of Ecosystems:

1. Natural ecosystem: Forests, ponds, and lakes.
2. Human-made (artificial) ecosystem: Gardens, aquariums, and crop fields.

Preparation of a self-sustainable artificial aquatic ecosystem

1. Take a large jar filled with water.
2. Provide oxygen through an oxygen pump (aerator) and fish food that is available in the market.
3. Add aquatic plants and animals.
4. Aquatic plants/Producers provide O₂ during photosynthesis.
5. Aquatic animals/Consumers release CO₂ for the process of photosynthesis.
6. Decomposers are also important for the natural cleaning of the aquarium.

Role of decomposers in an ecosystem

1. They clean the environment.
2. They decompose biodegradable substances into useful substances.
3. They release nutrients into the soil by decomposing dead and decaying matter, thus making the soil fertile.
4. They maintain the nutrient pool by returning the nutrients in the pool.

Food Chains and Webs

Plant → Grasshopper → Frog → Snake

Each step or level of the food chain forms a trophic level.

• The autotrophs or the producers are at the first trophic level. They fix up the solar energy and make it available for heterotrophs or consumers.
• The herbivores or the primary consumers come at second,
• small carnivores or the secondary consumers at the third
• larger carnivores or tertiary consumers form the fourth trophic level.

The flow of energy between trophic levels:

1. The flow of energy is unidirectional.
2. Terrestrial plants take about 1% of the Sun’s energy and change it to chemical energy.
3. A great deal of energy is lost as heat/is used for digestion/ doing work/ growth and reproduction.
4. An average of 10% of the food eaten is turned into its own body and made available for the next level of consumers.
5. Food chains are mainly of 3-4 trophic levels (because of the 10% law).
6. The number of producers is maximum and the number reduces in subsequent trophic levels.
7. Food webs are more common as compared to isolated food chains.
8. Biological magnification can be observed.

10 percent law: Only 10% of energy is transferred to the next trophic level. The remaining 90% of energy is used in life processes (digestion, growth, reproduction, etc.) by the present trophic level.

Food Chain	Food Web
i. Food chain is a series of organisms feeding on one another.	i. Food web consists of a number of interlinked food chains.
ii. Members of higher trophic level feed upon a single type of organism of the lower trophic level.	ii. Members of higher trophic levels can feed upon organisms of the lower trophic levels of other food chains.
iii. It does not have any effect on improving the adaptability and competitiveness of the organism.	iii. It improves the adaptability and competitiveness of the organism.
iv. Example: Grass → Grasshopper → Frog → Snake → Hawk.	iv. Example: A hawk might also eat a mouse, a frog, or some other animal. The snake may eat a beetle, a caterpillar, or some other animal.

Biological Magnification: Non-biodegradable pesticides accumulate progressively at each trophic level. This phenomenon is known as biological magnification.

The consequences of human beings occupying the top level in any food chain are:

1. A maximum level of bio-magnification occurs here because of progressive accumulation.
2. We get a very small amount of energy as only 10% of the previous energy gets transferred at each trophic level.

How do our Activities Affect the Environment?

Ozone Layer and How it is Getting Depleted

• Ozone (O₃) is a molecule formed by three atoms of oxygen.
• Ozone is a deadly poison.
• It shields the surface of the earth from ultraviolet (UV) radiation from the Sun. This radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.

Formation of ozone:

The high-energy UV radiations break down the O₂ molecules into free oxygen (O) atoms.

These oxygen atoms then combine with oxygen (O₂) molecules to form the ozone molecule.

Cause of Ozone depletion: Synthetic chemicals like chlorofluorocarbons (CFCs) which are used as refrigerants and in fire extinguishers lead to the depletion of the ozone layer.

Steps taken to limit the damage:

• Depletion of the ozone layer can be prevented by not using synthetic chemicals like CFCs, that deplete the O₃ layer.
• Many developing and developed countries have signed and are obeying the directions of UNEP (United Nations Environment Programme) to freeze or limit the production and usage of CFCs at 1986 levels.

Managing the Garbage we Produce

Biodegradable Substances	Non-biodegradable Substances
i. Substances that are broken down by biological processes are called biodegradable substances.	i. Substances that are not broken down by biological processes are called non-biodegradable substances.
ii. Examples – Wood, paper, etc.	ii. Examples – Plastic, DDT, etc.

Excess generation of biodegradable wastes can be harmful as:

1. Its decomposition is a slow process leading to the production of foul smells and gases.
2. It can be the breeding ground for germs that create unhygienic conditions.

The problems caused by non-biodegradable wastes are:

1. They cause biomagnification.
2. They increase pollution.
3. They make the environment unclean.
4. They kill useful microorganisms.

Eco-friendly activities are:

1. Walk or cycle for short distances to reduce the use of vehicles running on fossil fuels.
2. Use both sides of the paper to reduce its use. Fewer trees will be cut to make more paper.
3. Separation of biodegradable and non-biodegradable wastes.
4. Gardening
5. Use of gunny bags/paper bags in place of polythene/plastic bags.
6. Use of compost and vermicompost in place of fertilizers.
7. Harvesting rainwater, etc.

The reasons for the shift from plastic to kulhads and then finally to paper cups are:

• The use of plastic cups raised the concern about hygiene thus they were replaced by disposable plastic cups.
• Disposable plastic cups are non-biodegradable and harm the environment. They were thus replaced by kulhads.
• Kulhads made of clay on a large scale resulted in the loss of top fertile soil.
• Now, disposable paper cups are used because – the paper can be recycled, is biodegradable, and is an eco-friendly material that does not cause environmental pollution.

Class 10 Science Chapter 13 Our Environment NCERT Underlined PDF

Must Read: Our Environment Class 10 Important Questions with Answers to get an idea of the different types of questions asked from this chapter.

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