Name: carbon movement in living systems
Uploaded: 2019-03-11T09:21:40.000Z
Duration: 1 min 14 s
Channel: JoVE

K12 Standards

north-carolina-k-12-science-standard-course-of-study

NC K-12 Science Standard Course of Study

9-12

Biology

ecosystems-interactions-energy-and-dynamics

Ecosystems- Interactions, Energy, and Dynamics

LS.Bio.4.1

The Carbon Cycle

- [Instructeur] Dans le cycle du carbone,les atomes de carbone se déplacent dans l'écosystème. 
Pour commencer, durant la photosynthèse,les organismes autotrophes tels que les plantestransforment le carbone de l'atmosphère,le dioxyde de carbone,en énergie utilisable ingérée par les hétérotrophes. 
Ces organismes peuvent alors restituer le carbonedans l'atmosphère grâce à la respiration,ou dans le sol pendant la décomposition. 
Le dioxyde de carbone dans l'atmosphèreest aussi très soluble dans l'eau. 
Les océans constituent donc un grand réservoir de carbone. 
Le dioxyde de carbone réagit avec l'eaupour former de l'acide carbonique, puis des ions carbonate. 
Le carbonate de calcium dans les océanssert à fabriquer le squelette des corauxet les coquilles des mollusques. 
Le carbone peut aussi être stocké à court termedans des arbres longévives et dans le sol,ou pendant beaucoup plus longtempsdans le cas des combustibles fossiles,qui sont les restes organiquesd'organismes autrefois vivants. 
Enfin, le carbone stocké dans les sédiments et le solde la croûte terrestre peut fondre pour devenir du magmaet être libéré dans l'atmosphèrelors des éruptions volcaniques,un processus qu'on appelle le "dégazage".

Brüggemann, N., A. Gessler, Z. Kayler, S. G. Keel, F. Badeck, M. Barthel, P. Boeckx, et al. « Allocation de carbone et flux d’isotopes de carbone dans le continuum plante-sol-atmosphère : une revue ». Biogeosciences 8, n° 11 (28 novembre 2011) : 3457-89. [<a href="https://doi.org/10.5194/bg-8-3457-2011 » target="__blank">Source</a>]

Baldocchi, Dennis, Youngryel Ryu et Trevor Keenan. « Variabilité du cycle du carbone terrestre. » F1000Research 5 (26 septembre 2016) : 2371. [<a href="https://doi.org/10.12688/f1000research.8962.1 » target="__blank">Source</a>]

le cycle du carbone

Le carbone est la base de toute matière organique sur Terre et il est recyclé à travers l’écosystème lors de deux processus primaires : l’un dans lequel le carbone est échangé entre les organismes vivants, et l’autre dans lequel le carbone fluctue sur de longues périodes de temps entre les restes organiques fossilisés, l’érosion des roches et l’activité volcanique. Les activités humaines, y compris l’augmentation des pratiques agricoles et l’utilisation de combustibles fossiles, ont grandement affecté l’équilibre du cycle naturel du carbone.
 
 <h4>Cycle biologique du carbone</h4>
 
 Tous les êtres vivants sont composés de molécules organiques qui contiennent des atomes de l’élément carbone. Le carbone existe dans l’atmosphère sous forme de dioxyde de carbone gazeux, qui réagit avec l’eau pour former du bicarbonate. Pendant la photosynthèse, les producteurs primaires (ou autotrophes) transforment le dioxyde de carbone et le bicarbonate en composés organiques contenant du carbone, comme le glucose, afin de fournir de l’énergie pour la croissance, l’entretien et d’autres processus.
 
 Les hétérotrophes reçoivent du carbone organique pour la croissance et l’entretien en consommant des autotrophes. Grâce au processus de respiration cellulaire, ces molécules organiques sont décomposées pour libérer l’énergie stockée à l’intérieur. Les sous-produits de ce processus sont l’eau et le dioxyde de carbone, qui est libéré dans l’atmosphère par la respiration, poursuivant le cycle.
 
 Le carbone peut également retourner dans l’environnement sous forme de déchets animaux ou de matières en décomposition provenant d’organismes morts. Les décomposeurs, comme les bactéries et les champignons, décomposent ces matières en dioxyde de carbone et en composés organiques.
 
 <h4>Cycle géologique à long terme</h4>
 
 Le carbone est stocké pendant de longues périodes dans l’atmosphère, les grands plans d’eau, les sédiments océaniques, le sol, les restes d’animaux fossilisés et l’intérieur de la Terre. Le dioxyde de carbone de l’atmosphère se dissout dans l’eau de l’océan, réagit avec les molécules d’eau et il est converti en carbonates. Combinés à des ions calcium, ces carbonates constituent les coquilles en carbonate de calcium de nombreux organismes marins, comme les coraux et les huîtres. Lorsque ces organismes meurent, leurs restes sont décomposés et peuvent s’enfoncer au fond de l’océan et progressivement faire partie des sédiments. Ces sédiments forment finalement du calcaire, qui constitue le plus grand réservoir de carbone sur Terre.
 
 Les grands arbres avec une longue durée de vie peuvent également stocker du carbone dans leur corps pendant des siècles. En tant que puits (réservoir de carbone) à plus long terme, les restes d’organismes stockent le carbone sous forme de combustibles fossiles, comme le charbon, le pétrole et le gaz naturel, profondément dans la terre pendant des millions d’années. Le carbone stocké profondément sous la surface de la Terre peut revenir vers la surface et l’atmosphère lors d’éruptions volcaniques.
 
 <h4>Impacts humains sur le cycle du carbone</h4>
 
 La combustion des combustibles fossiles et du bois libère d’importantes quantités de dioxyde de carbone dans l’atmosphère, modifiant le climat mondial. En outre, la déforestation et l’augmentation des pratiques agricoles affectent le cycle naturel du carbone en réduisant la quantité de matière organique dans le sol, en diminuant le stockage du carbone et en augmentant les niveaux de gaz à effet de serre, comme le méthane, dans l’atmosphère.

Le cycle du carbone

Le carbone est à la base de toute la matière organique sur Terre et est recyclé par l’écosystème en deux processus principaux : l’un dans lequel le carbone est échangé entre ...

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Écologie

Ecosystems

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carbon movement in living systems

Carbon moves through living systems and Earth over short and long time scales. It is the basis of all organic matter on Earth, and it cycles through ecosystems by passing between organisms and by moving through rocks, oceans, and the atmosphere. Human activities, including farming and burning fossil fuels, have changed this balance.

In the biological carbon cycle, carbon dioxide in the atmosphere reacts with water to form bicarbonate. Primary producers, or autotrophs, use carbon dioxide and bicarbonate during photosynthesis to make organic compounds such as glucose. These carbon-containing molecules support growth, maintenance, and other life processes.

Heterotrophs get organic carbon by eating autotrophs. They break down these molecules during cellular respiration to release stored energy. Water and carbon dioxide are the main byproducts, and the carbon returns to the atmosphere through respiration. Carbon can also leave organisms as waste or as dead matter. Decomposers, such as bacteria and fungi, break this material down and release carbon dioxide and organic compounds back into the environment.

Carbon also moves through long-term geological storage. It can remain in the atmosphere, large water bodies, ocean sediment, soil, fossilized animal remains, and deep inside the Earth for long periods. In the ocean, dissolved carbon dioxide reacts with water and becomes carbonates. These carbonates combine with calcium ions to form calcium carbonate shells in marine organisms such as coral and oysters. When these organisms die, their remains can sink and become part of sediment, which may later form limestone, the largest carbon reservoir on Earth.

Large, long-lived trees can store carbon in their bodies for centuries. On much longer time scales, the remains of organisms become fossil fuels, including coal, petroleum, and natural gas, deep in the Earth. Carbon stored underground can return to the surface and atmosphere during volcanic eruptions. Burning fossil fuels and wood releases large amounts of carbon dioxide into the atmosphere, which affects global climate. Deforestation and increased agricultural practices also change the natural carbon cycle by reducing soil organic matter, lowering carbon storage, and raising greenhouse gases such as methane.

Carbon Movement in Living Systems

what is an ecosystem?

Ecosystem Zones and Climate

Ecosystems are shaped by living and nonliving parts of an environment, and they can be grouped as terrestrial or aquatic. Terrestrial ecosystems depend on climate. Aquatic ecosystems are divided into freshwater and marine systems, and depth affects water temperature and how much sunlight reaches the water. Terrestrial ecosystems are called biomes. A biome is defined by climate and by the organisms that live there. Near the equator, rainforests have high, aseasonal temperatures and high annual...

trophic levels

Food Chains and Energy Flow

Food chains show how energy and nutrients move through an ecosystem. Each organism holds a trophic level, or a specific place in that chain. The lowest level includes primary producers, which make their own food using energy from the sun or from chemicals. Organisms at the next levels are heterotrophs, which get energy from other organisms below them. Primary consumers are herbivores, and they feed on autotrophs, also called primary producers. Secondary and tertiary consumers are carnivores...

primary production

GPP, NPP, and Ecosystem Energy

Gross primary production and net primary production describe how energy enters and moves through ecosystems. Primary producers, or autotrophs, make their own food. They can do this by photosynthesis or chemosynthesis, and they can also gain energy by consuming other organisms. The rate at which producers capture and store this energy is called gross primary production, or GPP. Not all of the energy in GPP stays available to the rest of the ecosystem. Primary producers use some energy for...

production efficiency

Energy Transfer as Biomass Efficiency

Net production efficiency shows how much energy organisms turn into biomass for the next trophic level. It focuses on the usable energy stored in body tissue, not the energy lost as heat or excreted wastes. This makes it a key idea for understanding energy flow through ecosystems. As energy moves from one organism to the next, only biomass can serve as food for the next trophic level. The rest of the energy is used in metabolism and is lost over time. Net production efficiency, or NPE, is the...

trophic efficiency

Energy Loss in Food Chains

Trophic level transfer efficiency describes how much energy moves from one level of a food chain to the next. It shows why energy drops sharply as organisms eat and are eaten. In most ecosystems, only about 10% of the energy passes on. This energy loss follows the second law of thermodynamics. In living systems, much of the energy is lost as metabolic heat during respiration. Trophic level transfer efficiency, or TLTE, measures this transfer by comparing the energy produced at one trophic...

what are biogeochemical cycles?

Nutrient Recycling in Ecosystems

Nutrient recycling in ecosystems keeps the elements needed for life moving through living and nonliving parts of the environment. Elements such as water, carbon, nitrogen, sulfur, and phosphorus are present in limited amounts, so they must be conserved and reused. These movements are called biogeochemical cycles. These nutrients can exist in several chemical forms. They may spend long periods in the atmosphere, on land, under the land, or in aquatic environments. Decomposition is a key part of...

the water cycle

Water Movement Through Earth Systems

Water movement through Earth systems connects the hydrosphere, the atmosphere, the land, and living things. The hydrosphere includes every place where water is stored or moves. Because water supports living processes, its movement is important for ecosystem dynamics. The cycle starts when the sun warms surface water on land and in the oceans. That water evaporates and enters the atmosphere as vapor. Water can also move into the air by sublimation, which is ice changing directly into vapor, and...

the carbon cycle

Carbon moves through living systems and Earth over short and long time scales. It is the basis of all organic matter on Earth, and it cycles through ecosystems by passing between organisms and by moving through rocks, oceans, and the atmosphere. Human activities, including farming and burning fossil fuels, have changed this balance. In the biological carbon cycle, carbon dioxide in the atmosphere reacts with water to form bicarbonate. Primary producers, or autotrophs, use carbon dioxide and...

the nitrogen cycle

Nitrogen in Soil and Living Things

Nitrogen in soil and living things moves through ecosystems in several forms. Nitrogen atoms are found in proteins and DNA. Most animals and plants cannot use nitrogen gas, which is the main form of nitrogen on Earth. Nitrogen must first be changed into a usable form by nitrogen-fixing bacteria before it can move through food webs. About 78% of the air we breathe is nitrogen gas, but few organisms can use it in that form. Nitrogen fixation changes nitrogen gas (N2) into ammonia (NH3).

the phosphorus cycle

Phosphorus Movement in Soil and Water

Phosphorus moves through ecosystems mostly as phosphate ions in soil, water, sediment, and rocks. Unlike carbon, water, and nitrogen, it is not found in the atmosphere as a gas. It is also often a limiting nutrient, which means it is in short supply in many environments. Phosphorus is important in DNA, cell membranes, bones, and teeth. It is found in minerals, sediment, volcanic ash, and aerosols. As rocks and sediment weather over time, they release inorganic phosphate. That phosphate then...

the sulfur cycle

Sulfur in Ecosystems and Acid Rain

Sulfur moves through ecosystems as part of the chemical cycle that supports life. It is an important element in proteins and in amino acids such as cysteine, which helps give proteins their structure. On land, sulfur reaches ecosystems in several ways. Weak sulfuric acid can fall with precipitation, sulfur can drop directly from the atmosphere, rocks can weather and release sulfur, and geothermal vents can add it as well. Plants and microorganisms take sulfur up from the soil and change it...

bioremediation

Bioremediation in Soil and Oil Cleanup

Bioremediation uses prokaryotes, fungi, or plants to remove pollutants from the environment. It is a practical way to reduce harmful chemicals in contaminated soil and water. In agriculture, fertilizers and pesticides can leach into groundwater, streams, and lakes. Microbes and bacteria can help break down these toxins. One example is atrazine, an environmental toxin found in many fertilizers, which can be removed from soils by the bacterial species Rhizobium and Tricoderma sp. Bioremediation...

key terms and concepts

Explore how carbon moves through photosynthesis, respiration, decomposition, oceans, rocks, and fossil fuels, and how human activity disrupts the cycle.

Carbon Movement in Living Systems | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

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Carbon Movement in Living Systems

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