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

热力学第一定律说，
 
 能量不能被创造或破坏，只能被改变
 
 这个原则以典型的食物网用来证明
 
 在此，从太阳射出的光能
 
 首先被植物所利用为辐射能量，
 
 然后转化为化学能量
 
 储存为单一碳水化合物
 
 植物最终被动物消化
 
 在分解糖过程中，
 
 能量要么变成热能释放出来，
 
 要么在大分子储存为以备后用的化学能量储备
 
 或者传递给捕食者

Garcia、Hernan G.、Jane Kondev、Nigel Orme、Julie A. Theriot 和 Rob Phillips。"生物过程的热力学。"酶学方法492（2011）:27-59。[<a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3264492/" target="__blank">来源</a>]

热力学第一定律

热力学第一定律指出，能量不能被创造或毁灭，只能被转化。这可以在一个经典的食物网中得到证明，在这个食物网中，来自太阳的光能被植物利用为辐射能，转化为化学能，并以复杂碳水化合物的形式储存起来。然后，植物被动物吃掉，在消化过程中，糖以热能的形式释放能量。糖也会产生化学能，这些化学能要么被消耗殆尽，储存在糖原和脂肪酸等大分子中，要么被捕食者消耗掉。然后来自动物的废物和死有机物质被细菌和真菌分解并返回到土壤中以为植物生长提供食物并且继续循环。

<h4>热力学第一定律</h4>
 
在光合作用过程中，光子被用来制造植物用来生存和生长的复杂碳水化合物，氧气被释放到大气中。
 
植物最终成为食草动物的食物，在消化过程中，糖被分解，能量被释放出来，或者作为热量，或者从葡萄糖中提供化学能，从而驱动细胞过程，使动物得以生存和繁殖。它也可以作为化学能储存在大分子中。例如，糖原可以储存在肝脏或肌肉中，在高能量需求时可以快速获取。它也可以储存为脂肪酸形式的能量储备。最后，这种动物可能会将能量传递给食肉动物，食肉动物也会以类似的方式使用它。
 
每一步产生的废物也会返回到空气、水或土壤中，用于维持食物网。像细菌和真菌这样的分解者吃死了的有机物，然后把它送回土壤，这样植物就可以再次利用它来生长。

热力学第一定律指出，能量既不能被创造，也不能被消灭，只能发生转化。这一原理可以在经典的食网中得到演示……

Education

教育

JoVE Core

Biology

生物学

Cellular Processes

细胞结构与功能

Metabolism

新陈代谢

KEY TERMS AND CONCEPTS

关键术语与概念

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

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.

biology

JoVE Core系列通过300多节动画视频课简明易懂地讲解生物学中的关键概念，以及150余段视频展示科学家在现代实验室开展实际研究实验，让生物学变得平易近人。

Alabama Course of Study Science

from-molecules-to-organisms-structures-and-processes

From Molecules to Organisms: Structures and Processes

9-12.B.1.5

Next Generation Science Standards

High School

Life Science

ecosystems-interactions-energy-and-dynamics

Ecosystems: Interactions, Energy, and Dynamics

HS-LS2-4

new-york-state-science-learning-standards

New York State Science Learning Standards

matter-and-energy-in-organisms-and-ecosystems

Matter and Energy in Organisms and Ecosystems

HS-LS1-5.

HS-LS2-4.

Georgia Standards of Excellence

Ecology

SEC4.

SEC4.c

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Energy Flow in a Food Web

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