Understanding the Nitrogen Cycle

What percentage of the atmosphere is nitrogen?

• 78%

• 21%

• 10%

• 5%

What converts atmospheric nitrogen into nitrates during storms?

• Sunlight

• Lightning

• Rain

• Plants

Which type of bacteria fixes atmospheric nitrogen into ammonia?

• Denitrifying bacteria

• Nitrifying bacteria

• Nitrogen-fixing bacteria

• Decomposers

What is the role of nitrifying bacteria in the nitrogen cycle?

• Convert ammonia into nitrites and nitrates

• Convert nitrates into nitrogen gas

• Fix atmospheric nitrogen into ammonia

• Break down animal proteins into ammonia

What happens to the nitrogen in animal waste products?

• Converted back to atmospheric nitrogen

• Absorbed directly by plants

• Used directly by other animals

• Broken down by decomposers into ammonia

What do decomposers do in the nitrogen cycle?

• Fix atmospheric nitrogen

• Convert ammonia directly to plant proteins

• Convert nitrites to nitrates

• Break down dead material to release ammonia

What is the effect of denitrifying bacteria on soil nitrates?

• Convert them back to atmospheric nitrogen

• Convert them into animal feed

• Convert them into plant proteins

• Increase their concentration in the soil

Which process completes the nitrogen cycle by removing excess nitrates from the soil?

• Ammonification

• Decomposition

• Nitrification

• Denitrification