Nitrogen Cycle

Which definition best describes the Nitrogen Cycle?

• Converts nitrogen into a mineral

• How nitrogen circulates through the ecosystem

• How nitrogen is made into fertilizer

• How plants take up nitrogen

Organisms that need nitrogen to survive.

• only plants

• only animals

• only bacteria

• all living things

Gas that makes up 78% of our atmosphere.

• Oxygen

• Nitrogen

• Hydrogen

• Carbon Dioxide

Plants and animals cannot use nitrogen directly from the air.

• True

• False

The process that allows organisms to use nitrogen

• assimilation

• denitrification

• fixation

• ammonification

A correct path that nitrogen could take would be

• air -> animals -> plants -> bacteria

• animals -> air -> bacteria -> plants

• bacteria -> air -> plants -> animals

• air -> bacteria -> plants -> animals

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

_____ is the conversion of organic nitrogen into ammonia

• Nitrogen Fixation
• Ammonification
• Denitrification
• Assimilation 

Nitrification happens in the ______

• Air 
• Soil 
• Ground Water 
• Plants 

Majority of nitrogen fixation occurs by

• Biological nitrogen fixing organisms

• Lightning

• volcanic eruptions

• Haber–Bosch process