Nitrogen Cycle

What is the process of combining nitrogen gas with other elements to make nitrogen into usable compounds?

• nitrogen composition

• ammonia 

• nitrogen fixation

• denitrification

How much of the atmosphere is composed of nitrogen gas?

• 87%
• 38%
• 78%
• 21%

Organisms that break down dead plants & animals and release nitrogen back into atmosphere...

• bacteria
• plants
• animals
• producers

Organisms that need nitrogen to survive

• only plants
• only animals
• only bacteria
• all living organisms

If the atmosphere is 78% N₂, why can't we just get our nitrogen by breathing?

• We have no mechanism to break the triple bond of nitrogen between the atoms.
• Our lungs would be damaged by the N2.
• We need Oxygen for cellular respiration.
• The legumes take it up first.

Plants and animals cannot use nitrogen directly from the air.

• True
• False

After plants and animals contain nitrogen, what puts it back into atmosphere?

• decomposition

• precipitation

• condensation

• bacteria

What happens when organisms die and decay? 

• Their nitrogen turns to carbon

• Their nitrogen returns to the soil

• they keep their nitrogen

• They stay on earth forever

The process in which Nitrogen circulates and is recycled is called ____________

• The nitrogen cycle
• The water cycle
• The carbon cycle
• Nitrogen Fixation 

Nitrogen fixation happens in the ______

• Air 

• Soil 

• Ground Water 

• Plants