Nitrogen and Carbon Cycles

The nitrogen cycle is the process by which nitrogen, an essential element for life, is transformed and recycled in the environment.

• True
• False

The nitrogen cycle has four main stages, what are they?

We humans need nitrogen for our _________ and our proteins.

• DNA
• atmosphere
• hearing

We must absorb the nitrogen from our ______________.

• air
• food
• sun

Nitrogen in the atmosphere falls to the earth in the form of precipitation such as __________ or __________.

• rain, wind
• wind, heat
• rain, snow

Nitrogen is combined with hydrogen to make ammonia in a process that is called _______________fixation.

• nitrogen
• oxygen
• ammonia

Bacteria convert ammonia into nitrite and then nitrate in this stage. This is a form of nitrogen that plants can easily absorb.

• fixation
• nitrification
• ammonification

Dead plants and animals are decomposed by bacteria, releasing nitrogen back into the soil in the form of ammonia.

• fixation
• nitrification
• ammonification

Not all of the nitrate is absorbed. Some of it goes to the bacteria that releases the nitrogen back to the _______________ in a process called denitrifying.

• ground
• plant
• atmosphere

Bacteria and _____________ take the waste or dead animals and break the nitrogen down. It enters the cycle at nitrification.

• decomposers
• rain
• proteins