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Dead Zones in the Ocean
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What is the Nitrogen Cycle?
• The nitrogen cycle is the process in which nitrogen circulates among the air, soil, water, plants, and animals in an ecosystem.
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Why is it important?
• All organisms need nitrogen to build proteins, which are used to build new cells.• Enzymes• Skin• Hair• Nails
• Bones• Muscles
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Why is it important?
• It is an essential nutrient for plant growth.
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Where is it found?
• Nitrogen is most abundant in the atmosphere.– It makes up 78% of our atmosphere– N2 (Nitrogen gas)
• It is scarce in the geosphere, hydrosphere, and biosphere.
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The Nitrogen Cycle
• Nitrogen must be altered, or fixed, before organisms can use it.– Lightning– Bacteria
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What are nitrogen fixing bacteria?
• Nitrogen-fixing bacteria are bacteria that convert atmospheric nitrogen into ammonia– Only a few species of
bacteria can fix atmospheric nitrogen
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The Nitrogen Cycle
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Decomposers and the Nitrogen Cycle
• Nitrogen stored within the bodies of living things is returned to the nitrogen cycle once those organisms die.
• Decomposers break down decaying plants and animals, as well as plant and animal wastes.
• After decomposers return nitrogen to the soil, bacteria transform a small amount of the nitrogen into nitrogen gas, which then returns to the atmosphere to complete the nitrogen cycle.