The Nitrogen Cycle

Biology - Ecology

What percentage of the atmosphere is nitrogen?

78%

Where do plants get nitrogen from?

The soil

Why can’t plants use the nitrogen in the air?

The nitrogen in the air is unreactive and they can only use nitrogen compounds so the nitrogen in the air has to be turned into nitrogen compounds

Where do animals get nitrogen from?

Eating plants or other animals

What is nitrogen fixation?

The process of converting nitrogen in the air into nitrogen compounds for plants to use

What are two examples of nitrogen fixation?

lightning and nitrogen fixing bacteria

Explain how lightning works

Lightning has enough energy to make nitrogen react with oxygen in the air to form nitrates

What are the four types of bacteria?

Decomposers, nitrifying bacteria, nitrogen fixing bacteria, denitrifying bacteria

Explain how decomposers work

Decomposers break down rotting plants and animals and animals urea into ammonia. This ammonia then forms ammonium ions in the soil

Explain how nitrifying bacteria work

Nitrifying bacteria use nitrification to turn the ammonium ions in decaying matter into nitrates

Explain how nitrogen fixing bacteria work

Nitrogen fixing bacteria turns atmospheric N2 into nitrogen compounds

Explain how denitrifying bacteria work

denitrifying bacteria turn nitrates in the soil back into nitrogen gas