RBSE Class 11 Geography Notes Chapter 21 Bio-diversity

Go through these RBSE Class 11 Geography Notes Chapter 21 Bio-diversity contain important concepts so that students can score better marks in the exam.

Rajasthan Board RBSE Class 11 Geography Notes Chapter 21 Bio-diversity

Concept of Biosphere

  • All the places located on the Earth, where life is found in any form are included in the biosphere.
  • So far, the conditions favourable for life are found only on the earth.
  • Among the available bio-diversity on the Earth, from the microscopic protozoans to the giant whales and from micro-lichens to large-sized trees are included.
  • Biosphere energy and nutrients flow from one consumer level to another consumer level.
  • The biosphere is the result of the complex activities of the biotic and abiotic components found on the surface of the earth.
  • There are two types of adaptations in the organisms: Hereditary and Acquired.
  • Hereditary adaptation is obtained from birth, whereas the acquired adaptation is generated from the response of the organism to any particular stimulus.

Structure of Biosphere

  • The lithosphere, hydrosphere and atmosphere are included in the structure of the biosphere.
  • The lithosphere is the solid part of the Earth, which is about 29.2 percent of the entire Earth in the form of continents and islands.
  • From the point of view of the biosphere, the upper surface of the earth is important, because all the organisms receive nutrition only from the soil present on the lithosphere.
  • The oceans are spread over 70.8 per cent of part of the entire earth. About 72 per cent part of the Earth’s surface is covered with water, which is called hydrosphere.
  • The water available on the surface of the Earth is converted into a cyclic flow and then falls on the Earth as rainfall by the process of evaporations.
  • The envelope of the gases surrounding the surface of the Earth is called the atmosphere.
  • Many gases, water vapour and dust particles are found in the atmosphere.
  • Among the atmospheric gases, highest nitrogen (78%) and oxygen (21%) are present in the highest amount.

RBSE Class 11 Geography Notes Chapter 21 Bio-diversity


  • The number of species of living organisms and plants present in any natural region is called bio-diversity.
  • The term bio-diversity was first used by American entomologist E.O. Wilson in 1986.
  • There are countless organisms found in the earth, in which genetic, ethnic and ecological diversity is observed.
  • The properties of each organism are determined by the genes at the genetic level.
  • Assessment of different forms of the similar characteristics in any species of organisms, is called genetic diversity.
  • The description of the number of organisms of different species available in an ecosystem is called ethnic diversity.
  • The complexity of bio-species available in an ecosystem is called ecological diversity.

Bio-diversity in India

  • Due to geographical inequalities and variation of climate across the vast expanse of India, extensive bio-diversity of plants and organisms is found.
  • India has 6.5 per cent organism species and 8 per cent plant species of the world.
  • National Biological Diversity Policy was released on January 6, 2000. The bio-diversity bill was passed on December 2, 2002 in the Lok Sabha and on December 11, 2002 in the Rajya Sabha.
  • Our country is one of the 12 largest biological diversity countries in the world.

Hot Spots of Bio-diversity in India

  • Such parts of the world where there is an abundance of plant and animal species, and such rare species, which is not found in any other area, are called hot spot.
  • So far, 25 hot spots have been identified in the world, out of which two hot spots are situated in India, including the Western Ghats and the Eastern Himalayas.
  • Nearly 25 per cent of the plant species are found in the Western Ghats hot spot, where as 11,540 plant species are found in the eastern Himalayan area.

Threats To Bio-diversity

  • At present, the destruction of natural habitats of animals and plants, and increased pollution as a result of human economic activities, is the major human reason for the degradation of bio-diversity.
  • The extinction rate of different species is increasing continuously. If this rate of extinction continues to grow in the same way, many species of plants and organisms will become extinct in the near future.

Conservation of Bio-diversity

  • Keeping in mind the continued depletion in bio-diversity and keeping human interest in mind, the protection of bio-diversity in order to preserve bio-diversity and natural resources is called appropriate management.
  • Protection of trees in Indian culture was given importance since ancient times. In Indian culture, it is considered that a tree is equal to ten sons.
  • In our culture, the attention of the society has also been drawn towards protecting the living beings along with worshipping the trees through the fundamental principles of Ahimsa Paramodharma (Non-violence is the ultimate religion).
  • Efforts are being made to maintain artificial assimilation, improvement of habitat, restricting hunting, Wildlife Conservation Act, establishment of national parks and sanctuaries for the protection of the rapidly-declining bio-diversity in India.
  • So far, 18 biosphere reserve areas have been set up in India, out of which 9 have been recognised by UNESCO.
  • Four National Parks, 26 Sanctuaries, 35 Prohibited Sectors and 5 Zoos have been set up in Rajasthan for conservation of wildlife.

RBSE Class 11 Geography Notes Chapter 21 Bio-diversity

Diversity in Nature

  • Different types of variations found in living beings are the result of biological evolution which took place in millions of years.
  • Bio-diversity is also called biological diversity. The word biological diversity was first used by Norse and Menace in the 1980s, and again this word was abbreviated by W. G. Raman in 1985 as bio-diversity.
  • The highest bio-diversity in the world is found on both sides of the Equator and the lowest bio-diversity is found at the poles.
  • The maximum bio-diversity in the world concentrates in coral reefs, humid region, mangrove ecosystem and tropical ecosystem.

Concept of Bio-diversity

  • The theory and concept of bio-diversity has developed in the past years due to environmental degradation.
  • The survival of bio-diversity is very important for the sustenance of human life.
  • In the concept of bio-diversity, the species have a decisive position. In nature, the species give birth to new genetic types by the process of transition.
  • The state, nation and economic system of the world depend on natural resources only.
  • The value of bio-diversity is assessed on the basis of food value, medicinal value, social values, ethical, decorative value and genetic value.
  • Nature-provided bio-diversity is a boon for humans. Bio-diversity manifests directly and Indirectly in human beings with vital components, and along with this, it expects the human society to conserve it.

Bio-diversity Notes Important Terms

→ Bio-diversity: The number of organisms found in a given geographical area and their variation is called bio-diversity.

→ Biosphere: The domain in which the organisms exist and interact with hydrosphere, the atmosphere and the lithosphere found on the Earth.

→ Troposphere: The lowest layer of the atmosphere above the Earth, which extends from the ground to an average of 12 km.

→ Water Vapour: Water located in the state of vapour in the atmosphere of earth.

→ Photosynthesis: The complete process for the preparation of organic compounds with the help of sunlight by green plants.

→ Ecology: Science of study of relationships of organisms with their environment.

→ Gene: A basic unit of life formation.

→ Mineral: Natural substance with definitive chemical composition present on the surface, in which there are certain physical and chemical properties.

→ Conservation: Preservation of natural environment and the balanced use of natural resources, which will continue to serve their utility in the future.

→ Rare species: Species that rarely occur in limited areas of the world or in large areas are called rare species.

→ Hot Spot: Areas having high bio-diversity and rare species are called Hot Spots.

→ Temperate Forest: The vegetation that is found in the temperate regions of the world is called Temperate Forest.

→ Ozone Depletion: Thinning of the ozone layer due to the increasing amount of chloro-fluoro-carbon gases in the atmosphere.

→ Acid Rain: Rainfall of chemical nature caused due to the formation of nitric acid due to the reaction of Sulphur dioxide and nitrogen oxide with water vapour in the earth’s atmosphere.

→ Resource: Every substance found on Earth or on planets and sub-planets which is useful for humans, is called a resource.

→ Biosphere Reserve Zone: Dwelling space for the protection of rare and common plant and animal species, in which hunting is banned.

→ Equatorial Forest: Forest found between 5° north and 5° south latitudes on both sides of the Equator. They are also called evergreen forests.

→ Ecosystem: The living and dynamic mechanism generated from the mutual interaction and integration of all living and non-living factors in an environment.

→ Coral reef: Reefs formed by deposition of coral and other living marine organisms which are broader near the ocean floor, and are often immersed in seawater.

→ Torrid/Tropical Zone: Part of the Earth located between the tropics on both side of the equator.

→ Evergreen Forest: A forest which is green throughout the year. This type of vegetation is often found in the equatorial regions.

→ Fungus, (PL Fungi): Plant dependent on the products of other organisms for their diet. Fungal parasites and fungal saprophytes are its two types.

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