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Nutrient cycles (The Nitrogen Cycle (Stages of the Nitrogen Cycle:…
Nutrient cycles
The Nitrogen Cycle
Nitrogen is needed for use in amino acids to make proteins, as well as in nitrogenous bases to make RNA and DNA nucleotides and is used in ATP and ADP
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Nitrification, Nitrifying bacteria, Ammonia to Nitrites to Nitrates
Denitrification, Denitrifying bacteria, Nitrates to nitrogen gas
Nitrogen fixation, Nitrogen fixing bacteria, Nitrogen gas to ammonia, (Reduction)
Ammonification, Saprobiotic bacteria, Nitrogen containing compounds like amino acids and proteins to Ammonia
Fertilizers
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In natural ecosystems, nutrients are constantly recycled, and are not removed from the environment
However in farming, when crops and livestock are grown they are removed from the environment so the nutrients that are taken up by the plants and animals are not returned when they die
Environmental issues
It leads to a reduction in species diversity as plants which are adapted to soils high in nitrates out compete other species
It leads to leaching as inorganic fertilizers result in the soils containing more nutrients than the plant takes up so they dissolve in water and are drained into streams, river and lakes
Eutrophication
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Algae uses light to photosythesise so forms a layer on the surface of the water source so less light penetrates to plants at lower depths
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There is then an increase in the population of Saprobiotic bacteria which decomposes the dead plants and algae at the bottom the lake
Bacteria respire, reducing oxygen concentration of the water
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The Phosphorus Cycle
Phosphorus is used in ATP as well as Phospholipids to make new membranes, and in DNA and RNA nucleotides
The cycle
Phosphates in rocks are released through erosion and the use of fertilizers leading them to be dissolved in oceans lakes and soils
From the oceans lakes and soils the phosphates are absorbed by plants to be used in making ATP, DNA, RNA and phospholipids
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The animals then excrete some of the phosphates back into the oceans lakes and soils and take most with them when they die and decompose leaving phosphate ion as remains like bones
The remains of the organism can be eroded so it returns to the oceans lakes and soils and some are deposited to form rocks
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