TEST - 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 need nitrogen to survive

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

Plants and animals cannot use nitrogen directly from the air.

• True
• False

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

• decomposition
• precipitation
• condensation
• bacteria

Based on this diagram, which of the following can you infer is the chemical formula for gaseous nitrogen?

• N
• N₂
• N₃
• N₄

What happens when organisms die and decay? 

• Their bodies are lifted up
• 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 

_____ is the conversion of organic nitrogen into ammonia

• Nitrogen Fixation
• Ammonification
• Denitrification
• Assimilation 

How do animals get the nitrogen they need?

• From the air they breathe

• From the water they drink

• From the food they eat

• From the sun