Nitrogen is a gas that makes up nearly 80% of Earth's atmosphere.
Nitrogen is a key component of proteins and DNA.
Nitrogen can be directly absorbed by plants from the atmosphere.
Nitrogen is converted into a usable form by lightning.
What is the main reservoir of nitrogen in the nitrogen cycle?
What process converts atmospheric nitrogen into usable nitrogen compounds?
What process returns nitrogen back to the atmosphere?
What is the primary source of energy for nitrogen fixation?
What are the different forms of nitrogen found in the environment?
Nitrates
Proteins
Ammonium
N2
Water bodies
Living organisms
Soil
Atmosphere
Which processes contribute to the nitrogen cycle?
Ammonium to nitrite to nitrate
Nitrate to nitrogen gas
Incorporation of nitrogen into organic molecules
Bacteria
Nitrification
Denitrification
Assimilation
Nitrogen fixation
Where do nitrogen-fixing bacteria live?
Rizobium
Azotobacter
Cyanobacteria
Diazotrophs
Root nodules of legume plants
Soil
Wetlands
Marine environments
What is the role of denitrifying bacteria in the nitrogen cycle?
Use nitrate instead of oxygen for respiration
Nitrate to nitrogen gas
Create an oxygen-low environment
Energy source
Reduce
Anaerobic conditions