Carbon Cycle


 
 
Concept Explanation
 

Carbon Cycle

Carbon Cycle: Carbon is the basic constituent of all living beings. Its organic compounds play a major role in our life as carbohydrates, fats, proteins and nucleic acids. Food, fibres (cotton, jute), medicines, fertilizers, fuels—all contain compounds of carbon. There are three main reservoirs of carbon: (a) atmosphere, (b) oceans, and (c) carbonate rock, coal and petroleum.

The atmosphere, in which carbon is present as carbon dioxide, serves as the main reservoir of carbon. Some carbon dioxide is also found dissolved in water. Carbon dioxide constitutes 0.03 per cent of the atmosphere. Most of the carbon dioxide enters the living world through the process of photosynthesis. The amount of carbon fixed by photosynthesis per year is 4times10^1^3 to 9times10^1^3 kg. The process of photosynthesis takes place on land as well as in water. Carbon dioxide enters the producers by diffusion and is then utilized for photosynthesis.

  • During this process, producers use it to make carbohydrates. These are consumed by all living beings. The carbon in carbohydrate passes through different living beings as food.
  • There is also a continuous exchange of carbon dioxide between the atmosphere and water bodies like oceans, through the plants present in them. Some of the dissolved carbon dioxide is also trapped to form limestone (calcium carbonate) and other carbonate rocks.
  • Carbon dioxide returns to the atmosphere through respiration in plants and animals, decomposition of dead plants and animals, volcanic eruptions and combustion of fossil fuels. Thus, a carbon cycle operates in our environment, as a result of which the proportion of carbon dioxide in the atmosphere remains almost the same.
  • Sample Questions
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    Question : 1

    Which of the following contribute to the carbon cycle ?

    Right Option : D
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    Question : 2

    Choose the correct the correct sequences:

    Right Option : B
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    Question : 3

    In which one of the following processes carbon dioxide is not released ?

    Right Option : C
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