1. 2.2 Nutrient Cycles in Ecosystems
Nutrients are chemicals required for ___________ and other life processes.
Nutrients move through the biosphere in _______________________or exchanges.
Nutrients often accumulate in areas called _________________.
Without interference, generally the amount of nutrients flowing _______ a store equals the amount of nutrients flowing ___________.
Human activities can upset the ______________________of nutrient cycles.
Land clearing, agriculture, urban expansion, mining, industry, and motorized transportation can all _________________ the levels of nutrients more quickly than the stores can absorb them.
Excess nutrients in the biosphere can have unexpected _____________.
There are five chemical elements required for life.
____________, _________________, ______________, and ____________ cycle between living things and the atmosphere.
Phosphorus cycles in from ___________________________.
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2. Nutrient Cycles: The Carbon Cycle
Carbon atoms are a fundamental unit in___________of all living things.
Carbon is also an essential part of chemical processes that sustain _______.
Carbon can be _________________ in many different locations.
Short-term shortage is found in ____________ and _____________________,
in CO2 in the_______________________and in the _____ layers of the ocean.
Long-term storage is found in middle and lower ocean layers as ________ CO2 and in __________, oil, and ____ deposits in land and ocean sediments.
_______________________ traps many long-term stores of carbon.
Layers of soil and decomposing organic matter become ______________
on land and under the oceans.
Slowly, under great pressure over many years, _________________________ form.
Layers of shells also are deposited in sediments on the ocean floor, forming carbonate rocks like _____________________ over long periods of time.
Carbon stores are also known as _______________________.
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3. Nutrient Cycles: The Carbon Cycle (continued)
Carbon is cycled through ecosystems in a variety of ways.
_________________________: energy from the sun allows CO2 and H2O to react
______________________________________________________
Carbon in the atmosphere is transformed by plants into _________________.
Photosynthesis also occurs in _____________________ and algae in oceans.
______________________________: carbohydrates release energy in consumers
_____________________________________________
The energy released is used for __________, _____, and other life processes.
_____________________: decomposers break down large quantities of cellulose
Cellulose is a _________________ most other organisms cannot break down.
__________________________: CO2 dissolves in cold, northern waters and sinks
Ocean currents flow to the tropics where the water rises and releases CO2.
This process is called _______________________________.
____________________________________– volcanic eruptions can release CO2.
_____________________________also release CO2.
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4. Nutrient Cycles: The Carbon Cycle (continued)
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5. Nutrient Cycles: The Carbon Cycle (continued)
Many __________________________can influence the carbon cycle.
Since the start of the Industrial Revolution (160 years ago), CO2 levels have _________________ by 30 percent due to the increased burning of fossil fuels.
The___________in CO2 levels in the previous years was percent
Carbon is being ________________ from long-term storage more quickly than it naturally would as we ____________ coal and drill for oil and gas.
CO2 is also a ____________________, which absorbs heat in the atmosphere.
Clearing land for __________________________ and _______________________ reduces plants that can absorb and convert CO2.
Farmed land does not remove as much CO2 as _____________________does.
Clearing Land for
Agriculture
Urban
Expansion
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6. Nutrient Cycles: The Nitrogen Cycle
Nitrogen is very important in the structure of ________ and proteins.
In animals, proteins are vital for ___________________________.
In plants, nitrogen is important for__________________.
The largest store of nitrogen is in the atmosphere in the
form ___________.
Approximately ______________of Earth’s atmosphere is N2 gas.
Nitrogen is also stored in _______, and as organic matter in soil.
Smaller nitrogen stores are found in terrestrial ecosystems and
waterways.
Nitrogen is cycled through processes involving plants.
______________________________
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7. Nutrient Cycles: The Nitrogen Cycle (continued)
Nitrogen fixation is the conversion of N2 gas into compounds containing ________________ (NO3–) and _________________ (NH4+).
Both nitrate and ammonium compounds are usable by _________________.
Nitrogen fixation occurs in one of three ways.
____________________________– lightning provides the energy for N2 gas to react with O2 gas to form nitrate and ammonium ions.
Compounds formed by these ions then enter the soil via ____________.
This provides only a ______________ amount of nitrogen fixation.
___________________– nitrogen-fixing bacteria like Rhizobium convert N2 gas into ammonium ions
These bacteria grow on the root nodules of legumes like peas.
The plants provide sugars, while bacteria provide nitrogen ions.
_____________________– some cyanobacteria convert N2 into ammonium during the process of photosynthesis.
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8. Nutrient Cycles: The Nitrogen Cycle (continued)
Nitrification occurs when certain soil bacteria convert ___________.
Ammonium is converted into _________________ (NO3–) by nitrifying bacteria.
Ammonium is converted to__________(NO2–), which is then converted to nitrate.
Nitrates enter plant roots through the process of ______________.
These nitrogen compounds compose ________________________.
Herbivores then eat plants and use nitrogen for ______and protein synthesis.
Nitrogen is returned to the
atmosphere via ________________.
Nitrates are converted back to N2
by ______________________ bacteria.
N2 is also returned to the
atmosphere through volcanic eruptions.
Nitrification
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9. Nutrient Cycles: The Nitrogen Cycle (continued)
Excess nitrogen dissolves in _______________, enters the waterways, and washes into lakes and oceans.
The nitrogen compounds eventually become trapped in sedimentary rocks and will not be released again until the rocks undergo hundreds of years of ________________.
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10. Nutrient Cycles: The Nitrogen Cycle (continued)
_____________________can also affect the nitrogen cycle.
Due to human activities, the amount of nitrogen
in the ecosystem has ___________ in the last 50 years.
Burning fossil fuels and treating sewage releases
nitrogen oxide (NO) and nitrogen dioxide (NO2).
_____________ also releases nitrogen compounds that increase acid precipitation in the form of nitric acid (HNO3).
Agricultural practices often use large amounts of nitrogen-containing _________.
Excess nitrogen is washed away, or _________________, into the waterways.
This promotes huge growth in aquatic algae called _______________________________.
Algae blooms use up all CO2 and O2
and block sunlight, killing many _______________________________.
Algae blooms can also produce neurotoxins that poison animals.
Acid rain damaged these trees
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11. Nutrient Cycles: The Phosphorous Cycle
Phosphorus is essential for life processes in ________ and _________
Phosphorus is a part of the molecule that carries ______________ in living cells.
Phosphorus promotes root growth, stem strength, and seed production.
In animals, phosphorous and calcium are important for ____________________.
Phosphorus is not stored in the ________________________.
Instead, it is trapped in phosphates (PO43–, HPO42–, H2PO4–) found in__________ and in the sediments on the ________________________.
________________________ releases these phosphates from rocks.
_____________________, via acid precipitation or lichens, releases phosphates.
______________________, including wind, water and freezing, releases phosphates.
Phosphates are then___________________by plants, which are then __________ by animals.
Weathering does not occur until there is geologic uplift,
exposing the rock to chemical and physical weathering.
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12. Nutrient Cycles: The Phosphorous Cycle (continued)
Humans add excess phosphorus to the environment through mining for ______________________ components.
Extra phosphorus, often along with potassium, then enters the ecosystems faster than methods can replenish the _____________________________.
Humans can also reduce phosphorus supplies.
Slash-and-burning of forests removes phosphorus from trees, and it then is deposited as ash in waterways.
The Phosphorus Cycle
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13. How Changes in Nutrient Cycles Affect Biodiversity
Any significant changes to any of these nutrients
(C, H, O, N, or P) can greatly affect ________________________.
Carbon cycle changes contribute to climate change and _________________________________.
Slight temperature fluctuations and changes in
water levels can drastically change ____________.
Changes influence other organism in the
food webs.
Increased levels of nitrogen can allow certain plant
species to ___________________ other species,
decreasing resources for every species in the
Decreased levels of phosphorus can inhibit the
growth of ________________ that are very important
producers in many food chains.
Salmon are sensitive to temperature changes.
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