Some Essential Ecological
Chemical CYCLES
There are some major cycles that are
important for biologists to understand.
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The BIG PICTURE HERE…
Substances (Carbon, Nitrogen, and Water)
move back and forth through the BIOTIC
(ORGANIC) world and the ABIOTIC
(INORGANIC) world.
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5.
WATER CYCLE: a continuous process
wherein water moves from the Earth’s
surface to the atmosphere and back.
There are some basic part to this cycle.
Evaporation
Condensation
Precipitation
Transpiration (Evapotranspiration)
Runoff, snowmelt, ice storage, and
groundwater storage
WATER CYCLE
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EVAPORATION: LIQUID water absorbs energy
(heats up) and turns into a GAS (Surface to
atmos.).
CONDENSATION: Water vapor (GAS) in the
atmosphere looses energy (cools) and turns into
a liquid (clouds).
PRECIPITATION: occurs when droplets of water
that are formed during condensation get bigger
and fall back to Earth.
Transpiration (Evapotranspiration): water is
absorbed by plants and subsequently released back
into the atmosphere through their leaves.
2. CARBON & OXYGEN CYCLES
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PHOTOSYSNTHESIS & RESPIRATION
Producers take in carbon from CO2 and
produce oxygen while consumers take in
the oxygen and give off CO2
Photosynthesis (in the chloroplasts):
Sunlight
6CO2 + 6H2O
6O2 + C6H12O6
Cellular Respiration (in the mitochondria):
6O2 + C6H12O6 6CO2 + 6H2O + ATP (Energy)
The Essence!
Carbon is cycled (converted) from
Inorganic Carbon is to Organic
Carbon…and the other way around.
Photosynthesis:
Plants make FOOD from ENERGY
Cellular Respiration:
Organisms make ENERGY from FOOD.
The NITROGEN CYCLE
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Nitrogen is another important element for
living things.
Most organisms cannot get it directly from
the atmosphere.
Nitrogen by itself in the atmosphere is
called FREE nitrogen. Nitrogen that is
attached to other elements is called FIXED
nitrogen…that’s the kind we need.
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Organisms require nitrogen-compounds,
(proteins and nucleic acids).
Air is about 78% nitrogen gas (N2). That’s
where most of the nitrogen hangs out.
Most organisms can’t use atmospheric
(free) nitrogen as is. They need it
changed into nitrogen compounds.
Plants need their nitrogen "fixed", which means
as part of compounds such as:
ammonia (NH3)
urea (NH2)2CO
nitrate ions (NO3−)
NITROGEN FIXATION
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This is the process that changes free
nitrogen into the usable fixed kind.
Bacteria in the soil and in water change
the nitrogen into compounds called
nitrates /NO3-(nitrobacter) and nitrites
/NO2- (nitrosomonas).
These can be used by other living thing to
make proteins and other needed
compounds.
Lightning and industrial processes do this
too.
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When an organism dies, the nitrogen
compounds return to the ecosystem and
are reused.
Eventually they are broken down
completely (denitrification) and return to
the atmosphere…and the cycle begins
again…that’s why its called a cycle!
FYI…if you’re gonna take
biology in college…
There are four sub-processes involved in
the Nitrogen Cycle. You don’t have to
know this now, but…someday…
1. Nitrogen Fixation: breaks N apart so it can form compounds.
2. Decay: waste from life processes
3. Nitrification: bacteria converting ammonia to
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2
nitrites and nitrites to nitrates
4.
Denitrification:
nitrogen gas again.
bacteria converting nitrates to