Week 3 Notes
Biogeochemical Cycles
Cycling of Organic Matter
Cycling of Organic Matter
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The materials used in building the bodies of living organisms are limited to the
atoms and molecules that make up the planet.
•
There is no alternative source of matter.
•
Therefore, to maintain life on Earth, matter must be _____________.
•
Food is __________ matter. Every time you eat, organic matter that was once
part of other living things passes into your body.
•
Through the process of _______________, complex organic molecules are broken
down into simpler molecules.
•
Cells use these simple molecules to build the complex molecules that become part
of your own structure.
Decay
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Decomposers break down the organic matter in dead bodies and feces into small,
inorganic molecules that can be used by organisms again.
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Week 3 Notes
Properties of Water
•
__________________________________________
•
Water can be found in the biosphere in three states”
1. _________________
2. _________________
3. _________________
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Water is continuously entering and leaving living systems
Water: a Polar molecule
•
Water molecules have a ______________and a __________ causing
water molecule to be a polar molecule
•
Polar molecule – ___________________
_________________________________
•
The attraction between opposing charges of different molecules create
a special hydrogen bond.
•
Hydrogen bonds pull water molecules together
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Week 3 Notes
Biogeochemical Cycles
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Matter can neither be _________________________________
 It cycles through the biosphere.
 As it cycles, it follows certain characteristic pathways
•
These pathways are called “Biogeochemical Pathways”
Bio =
•
Geo =
A biogeochemical pathway can be defined as the complex cyclical transfer of
nutrients ...from the environment to an organism and back to the environment.
•
There are 3 major cycles to understand
 Carbon/Oxygen Cycle
 Nitrogen Cycle
 Phosphorus Cycle
Practice Questions
Pg 48 # 4,6,7,10,14
The Carbon Cycle
•
Also called the Carbon-Oxygen Cycle.
–
Refers to the flow____________________________________.
–
The main part of this cycle involves the interrelation between
______________ and ________________________.
•
What is the equation for photosynthesis and cellular respiration?
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Week 3 Notes
•
Carbon dioxide is also released by the activities of :
–
Volcanoes
–
Automobiles
–
Combustion of any source
–
Uplifting and weathering
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Week 3 Notes
Reservoirs for Carbon
Organic Carbon
•
Organic carbon is held in the bodies of all living things.
•
All living things die, and __________________ eventually returns the carbon to
the cycle in ___________ form.
•
There is one important exception to this rule: Some ecosystems such as ______,
store huge quantities of carbon in organic form
 _________
Inorganic Carbon
–
When Carbon is not in organic form it may be found in three main
reservoirs.
1. The Atmosphere
2. The Ocean
3. Earth’s Crust
Human Impact on the Carbon Cycle
•
Human have modified the global carbon cycle by:
– Mining stored carbon and burning it, increasing the amount of Carbon in
the atmosphere
– Humans are also increasing the amount of carbon dioxide in the inorganic
reservoir by clearing away vegetation in order to build or farm.
•
__________ can hold only so much carbon dioxide
Practice Questions
Pg 59 # 1,2,4,5a
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Week 3 Notes
The Nitrogen and
Phosphorus Cycles
The Nitrogen Cycle
•
The complex cycling of nitrogen between organisms and the environment.
•
The air is ______ % nitrogen.
•
The main component of most fertilizers is a nitrogen compound.
•
Nitrogen is a chemical that plants need to grow well.
– Nitrates are a group of nitrogen containing compounds that are unreadily
absorbed by the roots of plants
Nitrogen and Animals
•
Nitrogen is also needed for the construction of proteins and nucleic acids
– Muscle tissue
– Hair
– Bones
– Cell parts
– DNA
– RNA
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Week 3 Notes
Nitrogen Usage
•
Nitrogen is usually utilized in life in the form of _______________.
•
There are 2 main ways atmospheric nitrogen can be converted into useful forms.
1) ______________
2) ______________
Lightning
•
Lightning can force nitrogen and oxygen together to form __________
– These will fall with precipitation and be ___________________________ roots.
– The plants will change these into their own _____________.
– Animals eat the plants and reorganize those proteins into the ones they need.
Bacteria
– These can convert atmospheric nitrogen into nitrates.
– __________________________ bacteria can also be found in small lumps called
nodules on the roots of ___________.
– Legumes can utilize atmospheric nitrogen
– Legumes are members of the bean family and include:
•
Clover and Alfalfa…
Nitrogen and decomposers
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After an organism dies, it ____________.
•
Decaying matter which contains nitrogen produces ______________.
– Ammonia will degrade into ________________.
– Nitrites will degrade into __________________.
•
The nitrates will now re-enter the cycle.
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Week 3 Notes
Bacteria
•
Some bacteria will actually convert the nitrates back into atmospheric nitrogen.
•
_______________ bacteria.
•
These bacteria do not need oxygen -- _______________ respiration.
•
_________________________ – the process in which nitrates are converted to nitrites
and then to nitrogen gas
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Week 3 Notes
Phosphorus Cycle
•
Phosphorus is a nutrient required by all living things.
–
Component of _________ and __________
–
DNA
–
ATP
–
Phosphorus Cycle is simpler than the carbon or nitrogen cycles because it does
not involve movement through the ________________.
•
•
Phosphorus is used in only one important inorganic form…
–
______________________________
–
______________________________
After plants incorporate phosphorus...
–
It is transferred through the food chain
–
It is eventually returned to the soil.
•
Excretions of animals
•
Actions of decomposers.
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Week 3 Notes
The Phosphorus Cycle
•
Two methods of P recycling:
–
___________________________________
–
___________________________________
Long Term Cycle
•
Most common form: a part of rocks
•
Properties:
–
•
soluble - dissolve in water
Phosphates dissolve in water—erosion (_____________)carries them from land to
streams and rivers and then finally to the oceans
•
Oceanssediments may be thrust upward (____________)and once again form land
through geological activity
Short Term Cycle
•
Phosphates in water also enter the food chain through photosynthetic organisms
•
________________ of dead organismssoluble phosphates are absorbed by plants and
used during photosynthesis
•
Plants are eaten by animals
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Week 3 Notes
Practice Questions
Pg 66 #4,8,9,13,14,18
In preparation for your summative assessment on this section, complete the
following questions in your textbook. (Answers available upon request)
Pg 76 #1-6,10-12,14,23-26, 38
Send me your answers to questions 6, 10, 23-26 and 38, as well as any
questions you have about the information before you do your summative
assessment for this week.
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