Download nitrogen gas

The Nitrogen Cycle
Major
Processes:

Nitrification

Denitrification

Decomposition

Assimilation
Denitrification
Nitrogen Fixation
Nitrification
Components of the Nitrogen Cycle

N2 (nitrogen gas)


NH3 (ammonia)


In the atmosphere; cannot be used by plants or
animals
Found in soil; cannot be used by plants or animals
NO2 (nitrite)

Found in soil; cannot be used by plants or animals
Components of the Nitrogen Cycle
(Continued)

NO3- (nitrate) & NH4+ (ammonium)


Only compounds of nitrogen that plants can use
Various nitrogen compounds such as
amino acids

Many different compounds that living things need
for survival
Processes of the Nitrogen Cycle
Nitrification:

The process by which unusable nitrogen compounds
are changed into compounds used by plants and
animals.

Ex: Conversion of nitrogen gas (N2) to ammonium
(NH4+)


Carried out by nitrogen-fixing bacteria
Ex: Conversion of nitrogen gas (N2) to nitrate (NO3-)

Occurs when lightening strikes
Processes of the Nitrogen Cycle
Denitrification:

The process of changing complex nitrogen
compounds into atmospheric nitrogen

Ex: Conversion of nitrate (NO3-) to nitrogen
gas (N2)

Carried out by denitrifying bacteria
Processes of the Nitrogen Cycle
Decomposition:

The process of changing dead plants &
animals into simple nitrogen compounds.
Assimilation:

The process of changing usable nitrogen
compounds by plants into complex plant or
animal nitrogen compounds.
Switch to handout on Nitrogen Cycle
Back of Nitrogen Cycle Handout…
1.
What source of energy ultimately drives the
nitrogen cycle? Explain.
The Sun: It gives plants the energy to
absorb soil nitrates (NO3)- so the plant
can make protein and grow.
Back of Nitrogen Cycle Handout…
2. How do animals obtain nitrogen as shown in
Figure 3-13?
Animals eat plant or animal protein to
get “N”. They digest it and then use
amino acids to make protein.
Back of Nitrogen Cycle Handout…
3. In what form does nitrogen appear in the air?
Where does it come from?
N2 (nitrogen gas).
Bacteria break down plant & animal
protein and N compounds in soil.
Back of Carbon Cycle Handout…
4. What form on nitrogen are most plants able to
absorb? How does it get into that form?
Nitrates (NO3)
Special bacteria (nitrogen-fixers) are in
little nodules on roots of certain plantslegumes. Ex: Clover, peanuts,
soybeans, alfalfa
You can cross out #5 on your sheet 
Mineral/Rock cycle



Living organisms need other minerals, like Ca,
Mg, Fe, etc.
They come from the releasing of minerals from
rocks.
So, how does the rock cycle work and how are
minerals incorporated in the environment?
The mineral cycle
* See page 33 of textbook
What to study:




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HW from textbook and
any textbook readings
Class notes
Food web diagrams,
concept map, N,C and
H20 cycle diagrams
Vocabulary
Case Study:
Reintroduction of
Wolves