Biogeochemical Cycles

The process in which nitrogen circulates and is recycled is called

• The nitrogen cycle

• The carbon cycle

• The water cycle

• The phosphorus cycle

How is nitrogen "fixed" into a usable form for plants?

• Through action of bacteria only

• Through lightning only

• Through action of bacteria and lightning

• Through photosynthesis

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

Gas that makes up 78% of our atmosphere.

• Oxygen

• Nitrogen

• Hydrogen

• Carbon Dioxide

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

• nitrogen composition

• nitrogen fixation

• ammonia

• denitrification

What is the formula for atmospheric nitrogen?

• N

• N₂

• NH₃

• NO₃

What process occurs when dead plant and animal matter decomposes and nitrogen is released back into the atmosphere?

• Assimilation

• Fixation

• Ammonification

• Denitrification

Plants and animals cannot use nitrogen directly from the air.

• True

• False

According to this diagram, plants use nitrogen to make _________________________

• bacteria

• animals

• proteins

• decomposers

According to this diagram, plants absorb

• nitrates

• nitrogen fixing bacteria

• animals

• decomposers