How does Carbon enter the atmosphere in the first place?
As carbon dioxide from respiration and combustion.
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Why and what is carbon dioxide absorbed by?
Producers to make carbohydrates (glucose) in photosynthesis.
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What happens to the producers?
They get eaten by animals, this passes the carbon compounds along the food chain. Most of it is exhaled as CO2 during respiration. They eventually die.
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What happens to the dead organisms? (Carbon cycle).
They are eaten by decomposers and the carbon in their bodies is returned to the atmosphere as CO2. In some conditions decomposition is blocked (stored). The plant and animal material may be used as fossil fuels for combustion.
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What may some marine animals convert carbon into?
Marine animals may convert some of the carbon in their diet into calcium carbonate. This is used to make their shells.
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What happens over time to their shells? Then what?
The shells of dead organisms collect on the seabed and form limestone. Due to the Earths movements, this limestone may become exposed to the air.
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What happens to the limestone that's exposed to the air?
It's weathered and the Carbon is released back into the atmosphere as CO2.
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How is Nitrogen gas converted to Nitrate?
By Nitrogen-fixing bacteria in soil or root nodules. Lightning also converts nitrogen gas to nitrate compounds.
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What does the Haber process do?
The Haber process converts Nitrogen gas into ammonia used in fertilizers.
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What is ammonia converted into?
Ammonia is converted into nitrates by nitrifying bacteria in the soil.
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How are plants used in the Nitrogen cycle?
Plants absorb nitrates from the soil and use these to build up proteins, they are eaten by an animal and its biomass used to produce animal protein.
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What is the definition of Urea?
Urine.
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What is broken down by decomposers?
Urea and waste material. This results in nitrogen being returned to the soil as ammonia. Decomposers also break down the bodies of dead organisms resulting in Nitrogen being returned to the soil as ammonia.
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What is ammonia converted into?
Ammonia is converted to nitrate by nitrifying bacteria.
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What happens in waterlogged soil?
Denitrifying bacteria in the soil break down nitrates and return nitrogen to the air.
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