CYCLES

There are some major cycles that are important for biologists to
understand.

The LAW OF CONSERVATION
what itz all about YO!

Matter isn’t created…it ain’t destroyed either.

Hmmmm…whatchoo gonna do with all that matter?

Ooooh I know! Cycle it between the biotic (living) world
and the abiotic (non-living) world.

Simple right?
OF MATTER…datz
1. WATER CYCLE
1. WATER CYCLE

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.

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
Transpiration: water is absorbed by plants and subsequently
released back into the atmosphere through their
leaves.
Percolation: water filtering through the soil, sand,
rock into the groundwater supply.
Iffin’ yer interested…check these out too:
Interception, infiltration, runoff, and storage.
2. CARBON (CO2) CYCLE
2. CARBON (CO2) CYCLE

PHOTOSYNTHESIS & CELLULAR 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
This is making FOOD

6O2 + C6H12O6
(Sugar/Carbohydrates) from ENERGY (sunlight)
Cellular Respiration (in the mitochondria):
6O2 + C6H12O6
6CO2 + 6H2O + ATP (Energy)
ENGERGY (ATP) from FOOD (sugar…the
oxidation of glucose)
This is making
The Essence!
Carbon is cycled (converted) from
Inorganic Carbon is to Organic
Carbon…and the other way
around.
Now…don’t get mad at me, but…CO2…it’s inorganic even though it has
carbon. Sorry…it wasn’t my idea! Technically organic compounds
have to have carbon bonded to hydrogen (hydrocarbon).
Photosynthesis:
Plants make FOOD from ENERGY
Cellular Respiration:
Organisms make ENERGY from FOOD.
HUMAN IMPACT: Carbon Cycle

For 800 years before the Industrial Revolution the global CO2 levels
were fairly consistent.

Over the past 200 years there has been measureable change in
levels.

Human activity is largely responsible for this.

Burning of fossil fuels and deforestation are the primary causal
factors.

Consequence: increase in CO2 levels result in higher global
temperature. The rate is prohibitive to the dispersal of plants and
animals to regions in which they can survive. Polar summer ice is
jeopardy, and sea level rise is imminent as well.
The NITROGEN CYCLE
The NITROGEN CYCLE

Nitrogen is another important element for living things. It is needed
to synthesize amino acids, proteins, and nucleic acids (DNA/RNA).

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.

Organisms require nitrogen-compounds, (a.a.’s,
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)

Ammonium (NH4+)

urea (NH2)2CO

Nitrite (NO2-)

nitrate ions (NO3−)
NITROGEN FIXATION

This is the process that changes free nitrogen into
the usable fixed kind.

Bacteria in the soil, plant root nodules, and in water
change the nitrogen into compounds called nitrites
/NO2- (nitrosomonas) and then to nitrates /NO3(nitrobacter).

These can be used by the plants to make proteins
and other needed compounds.

Animals eat the plants…other animals eat those
animals, and the nitrogen gets used by them too.

Lightning and industrial processes also fix free
nitrogen.

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 N2 apart so it can form compounds.
2.
Nitrification: bacteria converting ammonia to nitrites
and then to nitrates (which what plants can
assimilate).
3.
Decay: waste from life processes (ammonification).
4.
Denitrification: bacteria converting nitrates to
nitrogen gas again.
Here’s the Upshot…in 4 Steps
1.
Free N2-in the air…can’t use it
2.
Nitrogen Fixation-Bacteria in soil, water, and plants
chemically change N2 into usable Nitrogen compounds.
3.
Decay-stuff dies and decomposes
4.
Denitrification-other bacteria turn the N back into N2 aka
Free Nitrogen.
That’s it!
Human Impact: Nitrogen Cycle




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Burning of fossil fuels and use of nitrogen-based fertilizers alter the
amount of bio-available nitrogen (this is HUGE limiting factor for
ecosystems).
Fresh water aquatic ecosystems: nitrogen is a major limiting factor for
plant growth. Increased plant populations mean more dead plants
eventually. These decompose which depletes O2 levels. This leads to
the death of other organisms. The sciency word for all of
this…EUTROPHICATION
Terrestrial ecosystems: Extra nitrogen can lead to nutrient imbalance in
trees, changes in forest health, and declines in biodiversity.
Since more nitrogen is available, carbon storage is affected. There’s
more than just the nitrogen cycle getting jacked up.
With factory farming, fertilizers are spread to increase crop yield, but
the unused nitrogen (nitrate mostly), can leach out of the soil into the
streams and rivers. This stuff ends up in our drinking water
Marine Ecosystems…too much nitrogen = depleted O2 and toxic
dinoflagellate blooms (RED TIDE).
4. The Phosphorus Cycle
4. The Phosphorus Cycle

Phosphorus is a super-important element that is a
key part of ATP, nucleic acid molecules (more on
DNA & RNA later…a lot more!), the phospholipid
membranes in cells, bone, shells…n’ other stuff too.

Ya know how NITROGEN is from the atmosphere?
Of course you do…we just talked about it.
Well…Phosphorous (most of it) is in the Earth’s soil
and rocks in compounds called phosphates (PO43-).
Most Phosphorus is stored in the crust as the
mineral Apatite aka…Calcium Phosphate
aka Ca5(PO4)3
 The intrusive igneous rock…granite, is where
you can find apatite, but it is also found in
metamorphic and sedimentary rocks too.
 Some Phosphorus is dissolved in fresh and
ocean water, or is stored in soil or in organic
matter.
 Plants can take phosphates from the soil
sorta like they do with NITROGEN. No
special bacteria for this one.

Human Impact: Phosphorus Cycle

Well…here we are again with out fertilizers…and
to get them…we mine! Runoff from mining and
from fertilizer use leads to buildup of phosphorus.

Too much phosphate (or nitrogen) ain’t a good
thing and can lead to problems such as lake
eutrophication (nutrient buildup) leading to
algal and bacterial blooms. These guys use up
the oxygen and BLAMMO!…dead fish
everywhere! NOT COOL