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CBSE Class 12th Biology Notes for Chapter 14 Ecosystem

                                                 Chapter 14 Ecosystem

  • An ecosystem is a functional unit of nature and comprises abiotic and biotic components.


  • Abiotic components are inorganic materials like air, water and soil whereas biotic components are producers, consumers and decomposers.


  • Four important components of an ecosystem:
    • Productivity
    • Decomposition
    • Energy flow
    • Nutrient cycling


  • Primary productivity is the rate of capture of solar energy or biomass production of the producers. Secondary productivity is the rate of assimilation of food energy by the consumers.


  • Decomposition involves three processes:
    • Fragmentation of detritus
    • Leaching
    • Catabolism 


  • Energy flow is unidirectional. First, plants capture solar energy and then, food is transferred from the producers to the decomposers.


  • The storage and movement of nutrient elements through the various components of the ecosystem is called nutrient cycling. Nutrient cycling is of two types:
    • Gaseous
    • Sedimentary


  • The biotic community is dynamic and undergoes changes with the passage of time. These changes are sequentially ordered and constitute ecological succession. 

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