Carbon Cycle

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Biogeochemical Cycle Noun

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[by-oh-jee-oh-kem-i-kuhl sy-kuhl]

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Biogeochemical Cycle

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The pathway by which a chemical element moves through the living and non-living parts of Earth, such as the biosphere.

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Example: This diagram shows the carbon cycle, where carbon moves between the air (atmosphere), living things (plants, animals), and the Earth (soil, fossil fuels).

Front

Reservoir Noun

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[rez-er-vwahr]

Back

Reservoir

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A component of the Earth system where a chemical element is stored, such as the atmosphere, oceans, or land.

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Example: This diagram shows Earth's main systems—atmosphere, hydrosphere, lithosphere, and biosphere—which act as large reservoirs where carbon is stored in the carbon cycle.

Front

Flux Noun

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[fluhks]

Back

Flux

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The movement or transfer of a chemical element, like carbon, from one reservoir to another within a biogeochemical cycle.

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Example: This diagram shows the carbon cycle, where arrows represent the flux, or movement, of carbon between the atmosphere, land, ocean, and living things.

Front

Photosynthesis Noun

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[foh-toh-sin-thuh-sis]

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Photosynthesis

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The process used by producers to convert atmospheric carbon dioxide and water into glucose using energy from sunlight.

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Example: This diagram shows a plant using energy from sunlight, water from soil, and carbon dioxide from the air to create its food (glucose) and release oxygen.

Front

Cellular Respiration Noun

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[sel-yuh-ler res-puh-rey-shuhn]

Back

Cellular Respiration

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The process where organisms break down glucose to release energy, producing carbon dioxide and water as byproducts.

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Example: This diagram shows how cells use glucose and oxygen to create energy (ATP), releasing water and carbon dioxide, which returns carbon to the carbon cycle.

Front

Combustion Noun

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[kuhm-buhs-chuhn]

Back

Combustion

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The process of burning organic material, such as fossil fuels, which rapidly releases carbon dioxide into the atmosphere.

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Example: This diagram shows that combustion is a chemical reaction where a fuel (hydrocarbon) burns in oxygen to release energy, water, and carbon dioxide.

Front

Decomposition Noun

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[dee-kom-puh-zish-uhn]

Back

Decomposition

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The breakdown of dead organic matter by microorganisms, which releases carbon dioxide into the atmosphere through their respiration.

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Example: This image incorrectly shows decomposition as breaking down a problem, a computer science concept, not the biological breakdown of organic matter in the carbon cycle.

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Diffusion Noun

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[di-fyoo-zhuhn]

Back

Diffusion

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The natural process by which carbon dioxide is exchanged and dissolved between the atmosphere and the surface of the ocean.

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Example: Carbon dioxide (CO2) from the air, a high concentration area, dissolves and spreads into the water, a lower concentration area, through the process of diffusion.

Front

Fossil Fuels Noun

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[fos-uhl fyoo-uhls]

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Fossil Fuels

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Carbon-rich energy sources like coal, oil, and natural gas, formed from the ancient remains of once-living organisms.

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Example: Fossil fuels like oil and gas are found in underground reservoirs, trapped by rock layers, and are extracted by drilling from the surface.

Front

Autotroph Noun

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[aw-toh-trohf]

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Autotroph

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An organism that produces its own food from inorganic sources, such as a plant using photosynthesis; also known as a producer.

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Example: This diagram shows a plant, an autotroph, using sunlight, water, and carbon dioxide to create its own food (glucose), a key part of the carbon cycle.