1. THE NITROGEN CYCLE

2. THE NITROGEN CYCLE All living things need nitrogen to make proteins.
Almost 80% of the atmosphere is nitrogen, however, nitrogen cannot be used directly by living things.
Nitrogen must be converted or “fixed” into a form that plants and animals can use.

3. NITROGEN FIXATION
Defn: The production of soluble nitrogenous compounds.
Nitrogen is fixed in 3 ways:
By nitrogen-fixing bacteria in soil or water
By By nitrogen-fixing bacteria living in plant/legume roots (Fertilizers)
By lightening (Nitrogen + Hydrogen + Oxygen)

4. Nitrogen Fixation
Nitrogen (N2) is converted into 3 forms that can be used by plants and animals:
Ammonium - NH4+
Nitrite - NO2-
Nitrate - NO3-

5. Where To Find Each Form of Nitrogen
Nitrogen gas - atmosphere
Ammonium - soil or water
Nitrates and Nitrites - soil, sometimes water

6. THE NITROGEN CYCLE The nitrogen cycle has three main components:
Ammonification- produces ammonium
Nitrification- produces nitrates
Denitrification- produces gaseous nitrogen

7. Ammonification
Ammonium is produced when nitrogen in animal waste and dead organisms decompose.
This is done by special ammonifying bacteria in soil and water.
Organic Nitrogen (proteins) --> Ammonia --> Ammonium
(Toxic)

8. Converted to Ammonium (NH4+)
Ammonification
Bacteria
Excretions
(contain Nitrogen)
Proteins in Animal
Contain Nitrogen
Converted to Ammonium (NH4+)
Protein in Plants
Death &
Decomposition
Bacteria

9. Ammonification
Plants (producers) can absorb ammonium from soil and use it in plant proteins.
Animals (consumers) can then eat ammonium in plant proteins and use it in their bodies.

10. Nitrification Nitrate is produced when:
1. Ammonium is converted to nitrite and then to nitrate.
2. nitrogen gas is converted to nitrate.
This is done by nitrifying soil or water bacteria .
Nitrate is the form of nitrogen that is easiest for plants to use.
Plants absorb it from the soil.

11. Nitrification 1 Nitrate (NO3-) Nitrite (NO2-) Ammonium (NH4+)
Nitrogen Fixing Bacteria
Nitrite Lost from Soil Leaching

12. Nitrification 2
Nitrogen Gas in Atmosphere
Nitrate (NO3-)

13. Nitrification
Nitrite and Nitrate can also be used by producers to make proteins.
The producers are then eaten by consumers and the nitrogen in their proteins is transferred to the consumer.

14. Denitrification
Occurs when denitrifying soil or water bacteria convert ammonia, nitrite, or nitrate back to nitrogen gas.
Nitrogen gas is release into the atmosphere.

15. Denitrification
Nitrogen Gas in Atmosphere
Nitrate (NO3-)

16. ASSIGNMENT………

17. assignment
Page 45 #1-5
Chart on page 51 - get two comparisons and two contrasting features.

18.