Nitrogen Cycle Quiz

What percentage of our atmosphere is made up of nitrogen?

• 21%

• 78%

• 55%

• 10%

Why is the nitrogen cycle important for living organisms?

• It helps produce oxygen for respiration.

• It is necessary for the production of water.

• It converts nitrogen into forms usable by living organisms for making proteins.

• It eliminates harmful nitrogen from the atmosphere.

What is the form of nitrogen that cannot be used by living things and must be converted?

• Organic nitrogen

• Atmospheric nitrogen

• Nitrate nitrogen

• Ammonia nitrogen

What is the role of the nitrogen cycle in the ecosystem?

• It moves nitrogen through the food chain from complex to simple compounds.

• It moves nitrogen through the food chain from simple inorganic to complex organic compounds.

• It moves nitrogen directly from the atmosphere to living organisms.

• It moves nitrogen from living organisms back into the atmosphere.

What is the chemical formula for nitrogen as it commonly occurs in the air?

• NH3

• NO3

• N2

• H2O

Ammonia is a compound of which two elements?

• Nitrogen and oxygen

• Hydrogen and oxygen

• Carbon and hydrogen

• Nitrogen and hydrogen

What is the chemical formula for nitrates?

• NH4

• NO2

• NO3

• N2O

Which of the following are usable forms of nitrogen for plants and animals?

• Nitrogen gas (N2) only

• Ammonia (NH3) only

• Nitrates (NO3) only

• Both Ammonia (NH3) and Nitrates (NO3)

What is the first step in the Nitrogen Cycle?

• Ammonification

• Nitrification

• Nitrogen Fixation

• Denitrification

Which step in the Nitrogen Cycle involves bacteria in soil converting nitrogen compounds back into nitrogen gas?

• Ammonification

• Assimilation

• Nitrification

• Denitrification