Name: energy flow in a food web
Uploaded: 2019-03-11T09:21:09.000Z
Duration: 37 s
Channel: JoVE

K12 Standards

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

NC K-12 Science Standard Course of Study

9-12

Earth and Environmental Science

Earth's Place in the Universe

ESS.EES.1.3

First Law of Thermodynamics

- La première loi de la thermodynamiqueveut que l'énergie ne peut être créée ou détruite,simplement transformée. 
On peut le démontrer grâce à une chaîne trophique classique. 
Ici, l'énergie lumineuse du soleilest d'abord exploitée sous forme de rayons par les plantes,puis convertie en énergie chimiquestockée sous forme de glucides complexes. 
La végétation finit par être consommée par les animaux. 
Au cours du processus de décomposition des sucres,l'énergie est soit libérée sous forme de chaleur,stockée sous forme de macromoléculesen tant que réserve d'énergie chimique à usage ultérieur,ou transférée à un prédateur.

Garcia, Hernan G., Jane Kondev, Nigel Orme, Julie A. Theriot et Rob Phillips. « Thermodynamique des processus biologiques. » Méthodes en enzymologie 492 (2011) : 27-59. [<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264492/ » target="__blank">Source</a>]

première loi de la thermodynamique

Le premier principe de la thermodynamique stipule que l’énergie ne peut être ni créée ni détruite, seulement transformée. Cela peut être démontré au sein d’un réseau alimentaire classique où l’énergie lumineuse du soleil est captée en tant qu’énergie rayonnante par les plantes, transformée en énergie chimique et stockée sous forme de glucides complexes. La végétation est ensuite consommée par les animaux et, pendant le processus de digestion, les sucres libèrent de l’énergie sous forme de chaleur. Les sucres produisent également de l’énergie chimique qui est soit utilisée en effectuant un travail, soit stockée dans des macromolécules comme le glycogène et les acides gras, ou ils sont consommés par un prédateur. Les déchets et la matière organique morte des animaux sont ensuite décomposés par des bactéries et des champignons et sont renvoyés dans le sol afin de fournir de la nourriture aux plantes pour croître et le cycle continue. 
 
 <h4>Le premier principe de la thermodynamique</h4>
 
 Pendant le processus de la photosynthèse, les photons sont utilisés pour fabriquer des glucides complexes que les plantes utilisent pour vivre et croître, et l’oxygène est libéré dans l’atmosphère.
 
 Les plantes finissent par devenir des aliments pour les animaux — herbivores — et pendant le processus de digestion, les sucres sont décomposés et l’énergie est libérée — soit sous forme de chaleur, soit pour fournir de l’énergie chimique à partir du glucose — afin de mener les processus cellulaires qui permettent à l’animal de survivre et de se reproduire. Elle peut également être stockée dans les macromolécules comme énergie chimique. Par exemple, le glycogène peut être stocké dans le foie ou les muscles et peut être rapidement accessible en période de forte demande d’énergie. Elle peut également être stockée comme une réserve d’énergie sous forme d’acides gras. Finalement, l’animal peut transmettre l’énergie à un prédateur, un carnivore qui l’utilise de la même façon.
 
 Les déchets de chaque étape sont également renvoyés dans l’air, l’eau ou le sol et sont utilisés pour maintenir le réseau alimentaire. Les décomposeurs comme les bactéries et les champignons mangent de la matière organique morte et la renvoient dans le sol afin qu’elle puisse être réutilisée par les plantes pour croître.

Première loi de la thermodynamique

La première loi de la thermodynamique stipule que l’énergie ne peut pas être créée ou détruite, mais seulement transformée. Cela peut être démontré dans le cadre d’un réseau alimentaire classique...

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Metabolism

Métabolisme

KEY TERMS AND CONCEPTS

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energy flow in a food web

Energy flow in a food web shows the First Law of Thermodynamics in action. Energy cannot be created or destroyed. It can only change form as it moves through living things and the environment.

Sunlight is the starting point. Plants capture radiant energy from the sun during photosynthesis and turn it into chemical energy stored in complex carbohydrates. At the same time, oxygen is released into the atmosphere.

Herbivores eat the plants and use those sugars during digestion. The energy is released as heat or used as chemical energy from glucose to power cellular processes that help the animal survive and reproduce. Some of that energy is also stored in macromolecules. Glycogen can be kept in the liver or muscles and used quickly when energy demand is high. Energy can also be stored as fatty acids.

That stored energy can then move to a predator, such as a carnivore, which uses it in a similar way. Waste products and dead organic matter from animals are broken down by decomposers like bacteria and fungi. The materials return to the soil, air, or water, and plants can use them again as the food web continues.

Energy Flow in a Food Web

what is metabolism?

Metabolism, Energy, and Cell Reactions

Metabolism is the set of chemical reactions that happen in a cell. It includes anabolism, which builds molecules, and catabolism, which breaks them down. These reactions help cells manage energy and keep life processes running. Cells use metabolism to turn food into energy, make cell parts, and remove waste products. Food stores potential energy in the bonds between atoms. Catabolic pathways break large food molecules into smaller ones and release that energy. Anabolic pathways use that energy...

first law of thermodynamics

Energy flow in a food web shows the First Law of Thermodynamics in action. Energy cannot be created or destroyed. It can only change form as it moves through living things and the environment. Sunlight is the starting point. Plants capture radiant energy from the sun during photosynthesis and turn it into chemical energy stored in complex carbohydrates. At the same time, oxygen is released into the atmosphere. Herbivores eat the plants and use those sugars during digestion. The energy is...

second law of thermodynamics

Entropy in Food Web Energy Flow

The Second Law of Thermodynamics explains why entropy increases as energy moves through a system. Entropy means the amount of disorder in a system. Each time energy is transferred or transformed, some energy is lost as unusable heat. That heat can raise the motion of nearby molecules for a short time and make the surroundings less ordered and more random. This idea also appears in a food web. Primary producers, such as plants, take in energy from the sun and make food. During this process,...

kinetic energy

Motion as a Source of Energy

Kinetic energy is the energy of motion. It appears when an object is moving and can do work or cause change. A waterfall is one clear example. Water behind a dam has potential energy, but when it rushes downward, that moving water has kinetic energy. When the water reaches the bottom and stops moving, its energy can become potential energy again. Kinetic energy also shows up in living systems. Plants absorb light particles, called photons, which move very fast and help create chemical energy...

potential energy

Stored Energy in Motion and Bonds

Stored energy in motion and bonds is called potential energy. It depends on the structure of an object or the position of matter in space. Raising a kettlebell changes its location and increases its potential energy. A stretched rubber band also stores potential energy, which can later change into kinetic energy. Chemical bonds between atoms hold another form of stored energy called chemical energy. These bonds involve attractive forces, and that energy can change into other forms during a...

free energy

Gibbs Free Energy in Chemical Reactions

Gibbs free energy is a measure of useful energy that can be taken from a chemical reaction to do work. It is written as G and named for scientist Gibbs, who discovered it. This energy is what remains after entropy is considered. A reaction can either take in energy or release it. Reactions that absorb energy are called endergonic reactions. Reactions that release energy are called exergonic reactions. The direction of energy flow helps show which type of reaction is happening. Plants carry...

activation energy

How Catalysts Lower Reaction Barriers

Activation energy is the minimum energy a chemical reaction needs to keep going. When the activation energy is higher, the reaction usually happens more slowly. Adding heat can speed the reaction because molecules move faster and collide more often. As reactants collide, bonds break and the reaction moves through an uphill phase. That step creates the transition state, which is an unstable, high-energy state of the reactants. After that, new bonds form, products appear, and free energy is...

hydrolysis of atp

ATP Breakdown and Energy Release

ATP breakdown releases energy for cell work. Adenosine triphosphate, or ATP, can lose one or two phosphate groups when water is added. This hydrolysis reaction is exergonic, which means it releases energy that the cell can use. When one phosphate group is removed, ATP becomes ADP, or adenosine diphosphate. Inorganic phosphate is also released. ADP can then be hydrolyzed again to form AMP, or adenosine monophosphate, after a second phosphate group is removed. ATP has a clear structure. It is...

phosphorylation

Phosphorylation and Protein Control

Phosphorylation helps control how proteins work in cells. It is the addition or removal of phosphate groups, and it is the most common chemical change that regulates cellular processes. These changes can alter a protein’s structure, activity, stability, location inside the cell, and interactions with other proteins. During phosphorylation, protein kinases move the terminal phosphate group from ATP to a specific amino acid side chain on a target protein. The amino acids most often...

induced-fit model

How Enzymes Adjust to Their Substrates

Enzymes speed up many chemical reactions in cells. They are biological catalysts, so they increase reaction speed without being consumed or permanently changed. They do this by lowering the activation energy needed to turn reactants into products. Enzymes are proteins that usually work by binding to a substrate, which is the reactant molecule they act on. They show substrate specificity, meaning they bind only certain substrates. This specificity depends mainly on the shape and chemical...

enzyme kinetics

Substrate Effects on Enzyme Rates

Enzyme kinetics examines how enzymes change the rate of a reaction. Enzymes speed reactions by lowering the activation energy of the reactants. The reaction rate is the speed at which an enzyme turns reactants into products, and it can be affected by several factors, including the number of available reactants. Scientists often study enzyme kinetics in a test tube with a fixed amount of enzyme. When more substrate, or reactant, is added, the reaction rate increases because the enzyme can make...

enzyme inhibition

Competitive vs Noncompetitive Inhibitors

Enzyme inhibitors are molecules that reduce enzyme activity by binding to enzymes. Cells use these inhibitors to help regulate normal enzyme function. Drugs and toxins can also block enzymes and change how they work. Some inhibitors bind at the active site, which is the part of the enzyme where the substrate normally fits. Competitive inhibitors do this by occupying the active site and preventing the substrate from binding. If the substrate concentration becomes high enough, it can outcompete...

feedback inhibition

How Cells Control Product Buildup

Cells use enzymes to run biochemical reactions and make the products they need. These reactions are happening constantly, and enzymes speed them up so they happen fast enough to matter. Enzyme activity also has to be regulated. Cells need the right amounts of starting materials, intermediate metabolites, and final products. If these substances build up too much or drop too low, the cell can be harmed. That is why cells use control systems to keep metabolic levels balanced. One important...

allosteric regulation

Allosteric Control of Enzyme Speed

Allosteric control changes enzyme speed when a molecule binds to a site other than the active site. That alternate binding spot is called an allosteric site. An enzyme can have more than one allosteric site. This type of control can raise or lower enzyme activity. Many enzymes with allosteric control are metabolic enzymes. They help with the breakdown or the building of specific molecules in cells. In allosteric inhibition, the effector molecule causes a shape change that lowers the enzyme's...

cofactors and coenzymes

Enzyme Helpers: Metals, Vitamins, and More

Enzyme helpers are needed for many enzymes to work properly. These helpers fall into two groups: cofactors and coenzymes. Cofactors are metallic ions, while coenzymes are non-protein organic molecules. Both can be tightly bound to an enzyme or attach only when the substrate binds. Cofactors are common in mature proteins, appearing in about 30% of them. They are often added as the enzyme folds and help with catalytic activity. Magnesium is one important cofactor, and it is needed by more than...

key terms and concepts

See how sunlight becomes chemical energy in plants, moves through herbivores and carnivores, and returns to the soil through decomposers.

Energy Flow in a Food Web | JoVE K12

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Energy Flow in a Food Web

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