The Nitrogen Cycle

Welcome! Please Do Now…1. Prepare for class: iPad, journal2. Do you know what room you are in tomorrow?3. Hand in your homework.4. Please take a webquest from the front. You may want a

textbook and/or your cornell notes on the nitrogen cycle.

5. Use your notes, text, and iPad to answer the questions on the webquest. You have 20 minutes to complete this task.

What is nitrogen?

• Nitrogen is– an ingredient of proteins and nucleic acids– essential to the structure and functioning of all

organisms– limiting plant nutrient

• Nitrogen has two abiotic reservoirs:1. the atmosphere (about 80% is nitrogen gas)

2. soil

© 2012 Pearson Education, Inc.

The nitrogen cycle depends on bacteria

• Nitrogen fixation– converts N2 to compounds of nitrogen that can

be used by plants– carried out by bacteria

© 2012 Pearson Education, Inc.

Voca

b W

ord!

N2 N2

LEGUMES!

Figure 37.21

Nitrogen (N2) in atmosphere

Plant Animal

Nitrogen-fixingbacteria in

root modules

Free-livingnitrogen-fixing

bacteria

Detritus

Decomposers

Ammonium (NH4)

in soil

Nitrifyingbacteria

Denitrifiers

Assimilationby plants

Nitratesin soil

(NO3)

8

6

5

3

4 7

2

1

Nitrogen Cycle Notes

What is nitrogen?

The nitrogen cycle depends on ___________________________________________.

How do legumes play a role in the nitrogen cycle?