Cycling of MATTER in Ecosystems Organisms need energy AND matter to
survive
Ex: molecules to build bones, muscle, fat While energy flows in one direction,
matter recycles in ecosystems The most important molecules that recycle
are water, carbon, nitrogen, phosphorus, sulfur and oxygen
(CHNOPS)
The Water Cycle
Water is necessary for organisms to maintain an internal balance and to transport molecules like sugars and enzymes
Water is a renewable resource that we access through a water shed
Water shed = area of land that catches rain and snow and drains or seeps into a marsh, stream, river, lake or groundwater
The Carbon Cycle
Required for all living organisms on earth Needed to make DNA, proteins, fats,
sugars In nature, found as CO2 (gas) and many
solids (in alive and dead organisms) Photosynthesis and respiration are key
processes to keeping the cycle going
Photosynthesis and RespirationPhotosynthesis (by plants)
CO2 + H2O C6H12O6 + O2
Respiration (by most organisms)
C6H12O6 + O2 CO2 + H2O
Carbondioxide Water Sugar Oxygen
sunlight
Carbondioxide WaterSugar Oxygen
Photosynthesis and Respiration Note how the OUTPUT of photosynthesis is
the same as the INPUT of respiration Note how the OUTPUT of respiration is the
same as the INPUT of photosynthesis
Matter CYCLES back and forth between photosynthesis and respiration.
This is where oxygen is recycled, too!
Nitrogen Cycle
Nitrogen is a key component of proteins and DNA
Nitrogen is present as gas in the atmosphere turned into a solid plants to use it
Nitrogen fixation- bacteria (land) or cyanobacteria (aquatic) turn N2 (gas) into NH3 and NH4
+ (solids)
Denitrification- bacteria in sediments of aquatic areas convert solids back into gas
Nitrogen Cycle
Ammonification also adds to NH3 in the soil. Process of decomposers converting detritus and eventually ammonia.
Nitrification- another type of bacteria convert the NH3 and NH4
+ solids into nitrate ions (NO3-) for plants to assimilate (absorb)
Nitrogen Cycle- Human Impacts Make sure to include impact of excess
nitrates/eutrophication, burning of fossil fuels, use of fertilizers that increases denitrification (research!)
The Phosphorus Cycle Phosphorus is an important building block of
DNA and ATP; all living things must have phosphorus
P is found in rocks, and enters food webs when plants take up phosphorus found in soil
Only one that doesn’t cycle through the atmosphere! (no gaseous form)
P is a limiting factor for primary productivity because it isn’t easy for plants to acquire.
The Sulfur Cycle
Most sulfur is found in oceanic sediments, rock and mineral layers on earth
Enters atmosphere through burning of fossil fuels, volcanic activity, forest fires, release of hydrogen sulfide by respiring bacteria
S is an impurity in coal and petroleum (human impact = burning of coal leading to smog and acid rain)
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