The Nitrogen Cycle: Transformations and Key Roles in Our Environment

The video explains the nitrogen cycle, highlighting its importance in the environment. It covers the chemical nature of nitrogen, emphasizing its unreactive triple bond. The process of nitrogen fixation by rhizobium bacteria is detailed, showing how nitrogen gas is converted into nitrates. The video also discusses ammonification and nitrification, where waste nitrogen is transformed into forms usable by plants. Finally, denitrification is explained, showing how nitrogen returns to the atmosphere, with a note on the environmental impact of nitrous oxide.

What percentage of the atmosphere is made up of nitrogen?

• 100%

• 21%

• 79%

• 50%

Why is nitrogen considered unreactive?

• It forms a double bond.

• It forms a single bond.

• It does not form any bonds.

• It forms a triple bond.

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

• They convert ammonium to nitrites.

• They fix nitrogen from the air into nitrates.

• They convert nitrates to nitrogen gas.

• They decompose organic matter.

What is the process called when nitrogen is converted into ammonium?

• Nitrogen fixation

• Ammonification

• Denitrification

• Nitrification

During nitrification, what is ammonium first converted into?

• Ammonia

• Nitrite

• Nitrate

• Nitrogen gas

What is the final step of the nitrogen cycle?

• Nitrogen fixation

• Ammonification

• Denitrification

• Nitrification

Which gas is a greenhouse gas that can remain in the atmosphere for over 100 years?

• Oxygen

• Nitrous oxide

• Carbon dioxide

• Nitrogen dioxide

What is the main function of bacteria in the nitrogen cycle?

• To fix nitrogen

• To absorb sunlight

• To produce oxygen

• To decompose plants

Which process involves the conversion of nitrates into nitrogen gases?

• Denitrification

• Nitrification

• Ammonification

• Nitrogen fixation

What is the role of bacteria in the denitrification process?

• They produce oxygen from nitrates.

• They fix nitrogen from the air.

• They convert nitrogen gas into nitrates.

• They use nitrate for respiration instead of oxygen.