Our Environment Notes Class 10

NCERT Solutions for Class 10 Science Notes Ch-15 Our Environment

# Environment:- The environment is everything around us. All our surroundings including the soil, air, water, plants and animals form the environment. Plants and animals need a healthy environment to survive.

# Eco-System:- An ecosystem is a system consisting of biotic and abiotic components that function together as a unit.

  • Biotic Components: All the living things. Ex: Human, Animals, etc
  • Abiotic Components: All the Non-living things. Ex: Air, Water, etc

             Structure of Ecosystem

    Biotic.                                Abiotic

 Components                    Components 

 Producers.                               Air

Consumers: herbivores.           Water

Carnivores: omnivores.            Soil

Decomposers                           Sunlight

# Types of Ecosystem:-

1. Natural ecosystem; Deserts, Forests, and oceans

2.Artificial ecosystem; Aquarium,Crop field,dams,gardens,zoo,park, etc.

#     Biotic Component of an ecosystem

  • Producer: Producers are the biotic Components which manufacture food with the help of sunlight by the process of photosynthesis.

Ex – Plants and blue-green algae

  • Consumers or heterotrophs: Consumers are those organisms which obtain food from plants directly or indirectly.

Ex – Herbivores, Carnivores, Omnivores, Parasites

  • Decomposers: Decomposers are those organisms which depend upon dead plants and animals.

Ex- Fungi, Bacteria 

# Food Chain:- A chain in which one organism eats another organism, and later that organism is consumed by another larger organism.

# Trophic Level:- The position that an organism occupies in a food chain is called Trophic Level.

Each step of the food chain forms a trophic level. The autotrophs or the producer are at the first trophic level.

*The flow of nutrients and energy from one organism to another at different trophic levels forms a food chain.

# Main points to Remember:-

1. The green plants in a terrestrial ecosystem capture about 1% of the energy of sunlight that falls on their leaves and converts it into food energy.

2.10 Percent Law:-

Only 10% of energy is transferred to the next trophic level while 90% of energy is used by the present trophic level in its life processes. This is called the 10% law.

            Tertiary consumer            1KJ

                        ↑                             ↑

            Secondary consumer      10KJ

                        ↑                             ↑

            Primary consumer           100KJ

                        ↑                             ↑

                Producer                      1000KJ   

                  Tertiary consumer

                    Large carnivores                                                       



                   Secondary consumer 

                       Small carnivores 

                 Spiders, Snakes, Seals, etc


                   Primary consumer

                      All herbivores



                 Plants, Blue Algae, Green Algae

# Food Web:- Food web is a network of food chains where all the chains are naturally interconnected.

Each organism is generally eaten by two or more other kinds of organisms which in turn are eaten by several other organisms.

A food chain is unidirectional where the transfer of energy takes place in only one direction.

Once the energy reaches the next trophic level it does not come back again. For example- energy which passes to the herbivores does not come back again to autotrophs.

                   Top Carnivores 









        The flow of energy in an ecosystem

# Biological Magnification:- the increase in the concentration of harmful chemical substances like pesticides in the body of living organisms at each trophic level of a food chain is called biological magnification.


        Grass   →    Deer      →      Lion

   (10 ppm) → (200ppm) → (5000ppm)

      DDT               DDT                   DDT

Maximum concentration of such chemicals gets accumulated in human bodies.

# Depletion of Ozone Layer:- Ozone (O3) layer is largely found in the stratosphere which is a part of our atmosphere from 12 km-50 km above sea level.

Ozone is formed as a result of the following photochemical reaction.

       O2 + O → O3 (Ozone)

Ozone layer is a protective blanket around the earth which absorbs most of the harmful UV (ultraviolet) radiation of the 

Sun, protects living beings from diseases like skin cancer.     

CFCs      Chlorofluorocarbons 

UNEP     The United Nations Environment Program 

# Managing the Garbage we Produce:-

*Biodegradable Wastes: Substances that are broken down by the biological processes are said to be a biodegradable waste. Examples; Kitchen waste, leaves, urine and cow-dung, etc.

*Non-Biodegradable Wastes: Substances that are not broken down by biological processes are said to be Non-Biodegradable. Examples; DDT, Mercury, and Lead.

# Review of the 4Rs…..

1.REDUCE : consumption at the source.

2.REUSE : goods as much as possible to give them a longer life.

3.RECYCLE : to the maximum4.RECOVER : transfer waste into resources.

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