The Nitrogen Cycle Why do organism need nitrogen

The Nitrogen Cycle • Why do organism need nitrogen? • What are the different forms of naturally Nitrogen? • All organisms require nitrogen to make amino acids, which in turn are used to build proteins. • Many different forms of nitrogen occur naturally in the biosphere – Nitrogen gas (N 2) – Nitrate ions (NO 3 -) – Nitrite ions (NO 2 -) – Ammonia (NH 3)

• What are the • There are several kinds of processes involved in the nitrogen involved in the cycle. nitrogen 1. Nitrogen fixation is the process of converting gas into ammonia (NH 3). cycle? This process is done by bacteria and • Vocabulary by lighting. Nitrogen fixation 2. Denitrification is the process of Denitrification converting nitrates (NO 3 -) and nitrites -) into nitrogen gas. (NO 2 Nitrification 3. Nitrification is the process of converting ammonia (NH 3) into nitrites (NO 2 -) and nitrates (NO 3 -)

• Bacteria or lighting converts the N 2 gas into ammonia (NH 3). Other bacteria in the soil convert the NH 3 into nitrates and nitrites. Producers use the nitrates and nitrites to make proteins. Consumers then eat the producers and reuse the nitrogen to make their own proteins. • When organism die, decomposers return the nitrogen to the soil as ammonia.

• Vocabulary • The nitrates may be taken up Denitrification again by producers. Other soil bacteria convert nitrates into nitrogen gas in a process know as denitrification. This process releases nitrogen into the atmosphere once again.

The Nitrogen Cycle N 2 in Atmosphere NH 3 NO 3 and NO 2 -