Nitrogen Cycle

Animals get the nitrogen they need...

• from the air they breathe

• from the water they drink

• from the food they eat

• from the Sun

What is the only form of nitrogen that non-legume plants can take in and use?

• Nitrates

• Nitrites

• Diatomic nitrogen

• Ammonium

What converts nitrogen gas into a useable form for plants and animals?

• bacteria
• fungi
• rain
• car exhaust 

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

• The nitrogen cycle
• The water cycle
• The carbon cycle
• The phosphorus cycle

Organisms that need nitrogen to survive

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

According to the diagram in Figure 6.3, what organism converts atmospheric nitrogen into nitrogen compounds that will later be used by plants?

• rabbits

• bacteria

• plants

• dead log

In Figure 6.3, which process converts nitrogen gas in the air into

• Nitrogen fixation

• Decomposition

• Respiration

• Denitrification

Excessive use of ________ on lawns and gardens can affect the nitrogen and phosphorus cycles in nearby lakes and streams.

• nitrogen

• fertilizers

• sun

• bacteria

The process by which plants absorb nitrates is

• assimilation

• denitrification

• Ammonification

• photosynthesis

Which of the chemical formulas represents the nitrogen in the atmosphere?

• N2

• NO3

• NH4