Cycles of the Earth & Biogeochemical Cycles Nitrogen Cycle Slides 60-78

Nitrogen cycle: Atmospheric nitrogen (N2) makes up nearly 78%-80% of air. Organisms can not use it in that form. Lightning and bacteria convert nitrogen into usable forms.

Nitrogen cycle: Only in certain bacteria and industrial technologies can fix nitrogen. Nitrogen fixation: Convert atmospheric nitrogen (N2) into ammonium (NH4+) which can be used to make organic compounds like amino acids. N2 NH4+

Nitrogen-fixing bacteria: Nitrogen cycle: Nitrogen-fixing bacteria: Some live in a symbiotic relationship with plants of the legume family (e.g., soybeans, clover, peanuts).

Nitrogen cycle: Some nitrogen-fixing bacteria live free in he soil. Nitrogen-fixing cyanobacteria are essential to maintaining the fertility of semi-aquatic environments like rice paddies.

The Cycle Series - Nitrogen Cycle https://www.youtube.com/watch?v=IaGNSmQQmBc

The nitrogen cycle Nitrogen comprises 78% of our atmosphere It is contained in proteins, DNA and RNA Nitrogen cycle = describes the routes that nitrogen atoms take through the environment Nitrogen gas cannot be used by organisms Nitrogen fixation = lightning or nitrogen-fixing bacteria combine (fix) nitrogen with hydrogen To form ammonium Which can be used by plants

Nitrification and denitrification Nitrification = bacteria convert ammonium ions first into nitrite ions then into nitrate ions Plants can take up these ions Animals obtain nitrogen by eating plants or other animals Decomposers get it from dead and decaying plants or other animals Releasing ammonium ions to nitrifying bacteria Denitrifying bacteria = convert nitrates in soil or water to gaseous nitrogen Releasing it back into the atmosphere

The nitrogen cycle

Humans put nitrogen into the environment Fully half of nitrogen entering the environment is of human origin

Nitrogen Cycle

Nitrogen Cycle Nitrogen needed to build DNA Ammonia Nitrates Nitrogen needed to build DNA Problem: Nitrogen in atmosphere (78%) is unusable Step 1: Soil Bacteria Nitrogen fixation: convert atmospheric nitrogen into ammonia Nitrification: ammonia converted into nitrates

Nitrogen Cycle Step 2: Producers absorb nitrates through their roots

Nitrogen Cycle Step 2: Producers absorb nitrates through their roots Step 3: Consumers ingest nitrates through the food chain

Nitrogen Cycle Step 2: Producers absorb nitrates through their roots Ammonia Ammonia Ammonia Step 2: Producers absorb nitrates through their roots Step 3: Consumers ingest nitrates through the food chain Step 4: Decomposers return ammonia to soil Cycle repeats