To obtain the nitrogen they need, animals depend on many different microscopic ____________________ to convert nitrogen at all stages of the nitrogen cycle.

Denitrifying, anaerobic bacteria convert nitrate into nitrogen gas that returns to the atmosphere. What does anaerobic refer to?

The atmosphere is made up of mostly nitrogen. The percentage of nitrogen in the atmosphere is approximately _____.

Decomposers make ammonium in the soil during the process of -

Ammonia and ammonium are compounds of -

Select all answers below that are stages of the nitrogen cycle.

The relationship between some plants and nitrogen-fixing bacteria is -

The nitrogen cycle converts _________________ nitrogen into a useful form that living organisms can use to build proteins and nucleic acids within their cells.