Carbohydrates are one of the major forms of energy for animals and plants. Plants build carbohydrates using light energy from the sun during the process of photosynthesis , while animals eat plants or other animals to obtain carbohydrates. Plants store carbohydrates in long polysaccharides chains called starch, while animals store carbohydrates as the molecule glycogen. These large polysaccharides contain many chemical bonds and therefore store a lot of chemical energy.
When these molecules are broken down during metabolism, the energy in the chemical bonds is released and can be harnessed for cellular processes. All living things use carbohydrates as a form of energy.
Both plants and animals like this squirrel use cellular respiration to derive energy from the organic molecules originally produced by plants. The metabolism of any monosaccharide simple sugar can produce energy for the cell to use.
Excess carbohydrates are stored as starch in plants and as glycogen in animals, ready for metabolism if the energy demands of the organism suddenly increase. When those energy demands increase, carbohydrates are broken down into constituent monosaccharides, which are then distributed to all the living cells of an organism. Glucose C 6 H 12 O 6 is a common example of the monosaccharides used for energy production. Inside the cell, each sugar molecule is broken down through a complex series of chemical reactions.
As chemical energy is released from the bonds in the monosaccharide, it is harnessed to synthesize high-energy adenosine triphosphate ATP molecules. ATP is the primary energy currency of all cells. Just as the dollar is used as currency to buy goods, cells use molecules of ATP to perform immediate work and power chemical reactions.
The breakdown of glucose during metabolism is call cellular respiration can be described by the equation:. Plants and some other types of organisms produce carbohydrates through the process called photosynthesis. During photosynthesis, plants convert light energy into chemical energy by building carbon dioxide gas molecules CO 2 into sugar molecules like glucose. Because this process involves building bonds to synthesize a large molecule, it requires an input of energy light to proceed.
The synthesis of glucose by photosynthesis is described by this equation notice that it is the reverse of the previous equation :. In plants, glucose is stored in the form of starch, which can be broken down back into glucose via cellular respiration in order to supply ATP. These are the conditions under which most reactions are carried out in the laboratory.
The system is usually open to the atmosphere constant pressure and the process is started and ended at room temperature after any heat that has been added or which was liberated by the reaction has dissipated. The importance of the Gibbs function can hardly be over-stated: it determines whether a given chemical change is thermodynamically possible.
Energy associated with objects in motion is called kinetic energy. For example, when an airplane is in flight, the airplane is moving through air very quickly—doing work to enact change on its surroundings. The jet engines are converting potential energy in fuel to the kinetic energy of movement.
A wrecking ball can perform a large amount of damage, even when moving slowly. However, a still wrecking ball cannot perform any work and therefore has no kinetic energy.
A speeding bullet, a walking person, the rapid movement of molecules in the air that produces heat, and electromagnetic radiation, such as sunlight, all have kinetic energy. What if that same motionless wrecking ball is lifted two stories above a car with a crane? If the suspended wrecking ball is not moving, is there energy associated with it?
Yes, the wrecking ball has energy because the wrecking ball has the potential to do work. This form of energy is called potential energy because it is possible for that object to do work in a given state. Objects transfer their energy between potential and kinetic states. Once the ball is released, its kinetic energy increases as the ball picks up speed. At the same time, the ball loses potential energy as it nears the ground. Other examples of potential energy include the energy of water held behind a dam or a person about to skydive out of an airplane.
Potential energy vs. Moving water, such as in a waterfall or a rapidly flowing river, has kinetic energy. Potential energy is not only associated with the location of matter, but also with the structure of matter. A spring on the ground has potential energy if it is compressed, as does a rubber band that is pulled taut.
The same principle applies to molecules. On a chemical level, the bonds that hold the atoms of molecules together have potential energy. This type of potential energy is called chemical energy, and like all potential energy, it can be used to do work. Aerobic and anaerobic respiration Aerobic respiration Respiration using oxygen to break down food molecules is called aerobic respiration.
Absent or in short supply. The products of respiration still contain energy. Carbon dioxide and water. The products do not contain stored chemical energy which can be used in respiration. Mammalian muscle: lactic acid. Yeast: ethanol and carbon dioxide.
Some plants: ethanol and carbon dioxide. The products still contain stored chemical energy which can be used in respiration. Relatively large amount.
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