The Nitrogen Cycle

The video explains the nitrogen cycle, highlighting its importance for life on Earth. Nitrogen, essential for living organisms, is abundant in the air but unusable in its gaseous form. The cycle begins with nitrogen-fixing bacteria converting nitrogen gas into nitrates, which plants absorb to make proteins. These proteins travel up the food chain, providing animals with necessary nitrogen. Decomposition returns nitrogen to the soil, where bacteria convert it into ammonium and then back into nitrates. Finally, denitrifying bacteria release nitrogen gas back into the atmosphere, completing the cycle. This process is crucial for recycling nitrogen into compounds vital for life.

Why can't plants and animals use nitrogen directly from the air?

• Because nitrogen is too heavy to be absorbed.

• Because nitrogen is toxic in its gaseous form.

• Because nitrogen is only available in the soil.

• Because nitrogen is in a gaseous form that is not usable.

What role do nitrogen-fixing bacteria play in the nitrogen cycle?

• They absorb nitrates from the soil.

• They release nitrogen gas back into the air.

• They convert nitrogen gas into nitrates.

• They decompose dead plants and animals.

How does nitrogen return to the soil from living organisms?

• Through direct absorption from the air.

• Through photosynthesis.

• Through the process of respiration.

• Through waste products and decomposition.

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

• They decompose organic matter.

• They fix nitrogen gas into nitrates.

• They convert ammonium compounds into nitrates.

• They convert nitrates into nitrogen gas.

In what conditions do denitrifying bacteria thrive?

• In acidic soil conditions.

• In high-temperature environments.

• In waterlogged, oxygen-poor soil.

• In dry, oxygen-rich soil.