Nitrogen Cycle and Fixation Concepts

Nitrogen is crucial for DNA, RNA, and proteins, making up 78% of the atmosphere but is inert. Through the nitrogen cycle, it becomes biologically active. Nitrogen fixation, aided by bacteria, converts nitrogen gas into ammonia, which plants absorb. Nitrification further processes ammonium into nitrates for plant uptake. Decomposers and denitrifying bacteria recycle nitrogen back to the atmosphere. Human activities, like the Haber-Bosch process, have increased nitrogen fixation, impacting agriculture and causing environmental issues like eutrophication.

What percentage of the atmosphere is made up of nitrogen gas?

• 92%

• 21%

• 78%

• 50%

What is the primary role of nitrogen-fixing bacteria?

• Release nitrogen back into the atmosphere

• Convert nitrogen gas into ammonia

• Absorb nitrogen from the air

• Convert ammonia into nitrites

Which type of plants commonly have nitrogen-fixing bacteria in their roots?

• Grasses

• Legumes

• Conifers

• Ferns

What is the process called that converts ammonium ions into nitrite ions?

• Ammonification

• Denitrification

• Nitrification

• Nitrogen fixation

How do consumers primarily obtain nitrogen?

• Through the consumption of plants or animals

• Through photosynthesis

• By absorbing it from the air

• By drinking water

What role do decomposers play in the nitrogen cycle?

• They fix nitrogen gas into ammonia

• They release nitrogen from dead matter

• They absorb nitrogen from the soil

• They convert nitrates back into nitrogen gas

What is the final step in the nitrogen cycle that returns nitrogen to the atmosphere?

• Ammonification

• Nitrification

• Denitrification

• Nitrogen fixation

What process has allowed humans to artificially fix nitrogen?

• Haber-Bosch process

• Photosynthesis

• Denitrification

• Nitrification

What environmental issue can result from excess nitrogen entering waterways?

• Global warming

• Acid rain

• Eutrophication

• Desertification

How have humans impacted the rate of nitrogen fixation on Earth?

• They have reduced it to zero

• They have doubled it

• They have had no impact

• They have decreased it by half