Carbon cycle
 Carbon in the form of carbon dioxide is used by plants to prepare glucose by the process of photosynthesis. The glucose is used to provide energy and to convert into other organic compounds When animals eat plants it enters the body of animals. During respiration energy and carbon dioxide are produced. The carbon dioxide goes back into the atmosphere. Another process which adds carbon dioxide back into the atmosphere is the combustion of fuels like coal and petroleum. The organic compound in plants and animals are also converted into carbonates, limestone, coal, petroleum, exoskeletons (shells) of some animals.   Carbon is an essential component of biological molecules like carbohydrates, fats, proteins, vitamins, nucleic acids etc.

the green house effect
Gases like carbon dioxide, methane, chloro fluro carbon(CFCs) traps the heat radiated by the earth and prevents the escape of heat from the earth. The increase in the presence of these gases in the atmosphere causes increase in the temperature of the atmosphere. This is called the greenhouse effect.     Greenhouse effect can cause melting of polar ice, increase in sea levels, flooding of coastal areas and submerging of islands.

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the carbon cycle is important in the ecosystem as it helps in the movement  of carbons-from the atmosphere and oceans into organisms and back again to the atmosphere and oceans.if this cycle is disturbed it may lead to serious consequences such as global warming and climate disruption

it is a natural process that warms the Earth's surface. When the Sun's energy reaches the Earth's atmosphere, some of it gets reflected back to space and the rest is absorbed and re-radiated by greenhouse gases.such as carbon dioxide,methane,chlorofluro carbons,etc