Nitrogen Cycle and Its Processes

The video tutorial explains the nitrogen cycle, highlighting its importance in building DNA molecules. It covers processes like nitrogen fixation, nitrification, and denitrification, showing how nitrogen is converted into usable forms by bacteria. The role of plants and animals in the nitrogen cycle is discussed, along with the contribution of decomposers through ammonification. The video also explains how lightning can break atmospheric nitrogen, forming nitrates that enter the soil. A practice quiz is provided at the end for students to test their understanding.

What percentage of the atmosphere is composed of nitrogen?

• 21%

• 78%

• 50%

• 10%

Why is atmospheric nitrogen not directly usable by most life forms?

• It is in a gaseous state.

• It is toxic.

• It has stable triple bonds.

• It is too abundant.

What is a nitrogenous base a part of?

• Lipids

• Proteins

• Nucleotides

• Carbohydrates

What is the first step in the nitrogen cycle involving bacteria?

• Nitrification

• Denitrification

• Ammonification

• Nitrogen fixation

During nitrification, ammonium is converted into what?

• Nitrogen gas

• Nitrates

• Ammonia

• Nitrites

What process do decomposers perform in the nitrogen cycle?

• Ammonification

• Denitrification

• Nitrification

• Nitrogen fixation

How does nitrogen move up the food chain?

• Through water absorption

• By being consumed by animals

• Through photosynthesis

• By decomposing

What natural phenomenon can break apart atmospheric nitrogen?

• Rain

• Wind

• Lightning

• Earthquakes

What do nitrogen oxides form when they react with water?

• Nitrogen gas

• Nitrites

• Ammonium

• Nitrates

What happens to nitrates formed by lightning when it rains?

• They are added to the soil

• They are absorbed by plants

• They decompose

• They evaporate