Nitrogen cycle

What is the nitrogen cycle?

The nitrogen cycle describes how nitrogen moves through the atmosphere, soil, water, and living organisms.

Why is nitrogen essential for life?

Nitrogen is essential for building proteins and DNA in all living organisms.

What is nitrogen fixation?

The process of converting nitrogen gas (N₂) into usable forms like ammonia (NH₃) or nitrates (NO₃⁻).

What role do lightning and nitrogen-fixing bacteria play in nitrogen fixation?

Lightning converts N₂ into nitrates (NO₃⁻), while nitrogen-fixing bacteria convert N₂ into ammonia (NH₃).

What is nitrification in the nitrogen cycle?

Nitrification is the conversion of ammonia (NH₃) into nitrites (NO₂⁻) and then into nitrates (NO₃⁻) by nitrifying bacteria.

What is assimilation in the context of the nitrogen cycle?

Assimilation is when plants absorb nitrates (NO₃⁻) from soil to build proteins and DNA, and animals obtain nitrogen by eating plants or other animals.

What occurs during ammonification?

Ammonification is the process by which decomposers break down organic nitrogen and return it to the soil as ammonia (NH₃) or ammonium (NH₄⁺).

What is denitrification?

Denitrification is the conversion of nitrates (NO₃⁻) back into nitrogen gas (N₂) by anaerobic bacteria.

What are the environmental impacts of excess nitrogen from fertilizers?

Excess nitrogen can lead to eutrophication, causing harmful algal blooms and oxygen depletion in water bodies.

How does burning fossil fuels affect the nitrogen cycle?

Burning fossil fuels releases nitrogen oxides (NOₓ), contributing to acid rain and smog.

What is eutrophication?

Eutrophication is a process caused by excess nitrogen that leads to rapid algae growth, subsequent oxygen depletion, and harm to aquatic life.

How do decomposers affect the nitrogen cycle?

Decomposers break down dead organisms, returning nitrogen to the soil for reuse in the ecosystem.

Why do plants need nitrogen?

Plants need nitrogen to produce essential molecules like proteins and nucleic acids.