Nitrogen Cycle

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Nitrogen Noun

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[ny-truh-jen]

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Nitrogen

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An essential chemical element required by all living cells to build vital organic molecules like proteins and nucleic acids.

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Example: This diagram shows how nitrogen is cycled in the soil. Bacteria perform nitrogen fixation, decomposers break down matter, and plants absorb the nutrients.

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Nucleic acids Noun

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[noo-klee-ik as-ids]

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Nucleic acids

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Complex organic molecules, such as DNA and RNA, that carry genetic information and are essential for all known life forms.

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Example: This image shows that a nucleotide, the building block of nucleic acids, is made of a phosphate, a sugar, and a nitrogenous base.

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Nitrogen Fixation Noun

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[ny-truh-jen fik-sey-shuhn]

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Nitrogen Fixation

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The chemical process by which atmospheric nitrogen gas is converted into usable inorganic compounds like ammonia by certain microorganisms.

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Example: This image shows the roots of a plant with special bumps called nodules, which house bacteria that perform nitrogen fixation.

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Ammonia Noun

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[uh-mohn-yuh]

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Ammonia

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A compound of nitrogen and hydrogen that is a key product of nitrogen fixation and ammonification in the nitrogen cycle.

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Example: This image shows a 3D model of an ammonia molecule (NH3), which consists of one central nitrogen atom bonded to three hydrogen atoms.

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Nitrogen-fixing bacteria Noun

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[ny-truh-jen-fik-sing bak-teer-ee-uh]

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Nitrogen-fixing bacteria

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Microorganisms living in soil or plant roots that are responsible for converting atmospheric nitrogen into ammonia through nitrogen fixation.

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Example: This diagram shows how nitrogen-fixing bacteria live in nodules on the roots of legume plants, exchanging nitrogen for carbon in a symbiotic relationship.

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Ammonification Noun

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[uh-moh-nuh-fi-key-shuhn]

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Ammonification

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The process where decomposers break down organic nitrogen from waste and dead organisms, converting it into inorganic ammonia.

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Example: When plants and animals die or produce waste, decomposers like bacteria and fungi break down their organic matter, releasing nitrogen into the soil as ammonia.

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Decomposers Noun

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[dee-kuhm-poh-zers]

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Decomposers

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Organisms, such as bacteria and fungi, that break down dead organic material, recycling essential nutrients back into the ecosystem.

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Example: This image shows examples of decomposers, such as fungi and bacteria, which are organisms that break down dead organic matter, returning nutrients to the environment.

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Nitrification Noun

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[ny-truh-fi-key-shuhn]

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Nitrification

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The biological oxidation of ammonia into nitrites and subsequently into nitrates, performed by specialized microorganisms in the soil.

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Example: Soil microbes perform nitrification by converting ammonia first into nitrite, and then into nitrate, a key process in the nitrogen cycle.

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Nitrifying bacteria Noun

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[ny-truh-fy-ing bak-teer-ee-uh]

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Nitrifying bacteria

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Specialized soil bacteria that obtain energy by oxidizing ammonia and nitrites, carrying out the essential process of nitrification.

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Example: This diagram shows bacteria on plant roots taking nitrogen gas from the air and turning it into nitrogen compounds for the plant.

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Nitrites Noun

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[ny-tryts]

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Nitrites

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An intermediate nitrogen compound formed during the first stage of nitrification when ammonia is oxidized by certain bacteria.

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Example: This diagram shows the full Nitrogen Cycle, where nitrogen changes form. It omits the key step where ammonia becomes nitrites before turning into nitrates.