Extreme Biology

Themes in Biology - Energy Transfer

An Abundant Source of Energy

by Jacob (AP Biology)

Energy is all around us, but what does it do? Energy allows movement to happen, energy is in heat, and energy is needed for life. Energy transfers on a large scale of animal to animal to a small scale of cell to cell. Energy is constantly transferring and will continue transferring or life can not exist.

Molecular
Energy transfer can occur even in the smallest levels. In the molecular level, energy is in the bonds that bind together carbohydrates like glucose. When glucose’s bonds are split energy is released. Once it is released the energy is used and is gone and more energy is needed. This means more glucose bonds need to be broken to get that energy. To get the glucose it has to be given it from another part of the cell but that is getting into another example (Campbell, 70).

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Cellular

An example of energy transfer in the cellular level can be found in the process of photosynthesis. Photosynthesis takes place in a chloroplast inside of a mesophyll cell. In photosynthesis light energy from the sun is transferred from photons to a chemical energy in glucose. This process starts by going through the light reactions. This is where the photo part takes place and energy from the sun is harnessed into a chemical energy. Next the Calvin Cycle takes place. This is where the synthesis part happens where, with a little help from carbon fixation, the actual sugar glucose is made (Campbell, 181-183).

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Another example with energy transfer in the cellular level is in cellular respiration. Most of cellular respiration takes place in the mitochondria. After glycolysis, glucose has been broken down into pyruvate, (creating two ATP), pyruvate goes into the mitochondria and under goes the citric acid cycle producing two more ATP. Then all the electrons carried by NADH and FADH are transported to go through oxidative phosphorylation. This is where the electron transport chain and chemiosmosis take place producing 32 ATP. This process is basically how energy transfers from the chemical energy in food to energy our body can use (Campbell, 160-162).

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Organismal
There is even an example of heat transfer in an organismal level. In endotherms when undergoing a situation where they are moving a lot, they are using a ton of energy. When this energy is used, heat is released. This heat raises the temperature in the body. When this raise occurs a part of the nervous system triggers the endotherms body to skin to produce sweat. This sweat evaporates taking away the heat and thus cooling the body. This is the transfer of energy out of the body (Campbell, 837)

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Population
Another example of the transfer of energy can be shown in an individual population. In a population of tigers, those who can get the most energy will survive the best because energy is needed to function. In other words, the tigers that are the best at hunting prey will live longer than those who are not as good. This is because every time an animal eats it receives a portion of the eaten animals’ energy. So those tigers that can not catch and eat prey will die. So an animals’ population is affected by the ability to get energy from its prey (Campbell, 1148-1149)

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Community
Energy transfer occurs on a larger scale in a community. This includes several different populations in an ecosystem. An example of this is basically the food web. Plants take in energy using photosynthesis. A herbivore like a rabbit might eat the plant taking only one tenth of its energy. Then a coyote might see the rabbit and eat it once again taking a tenth of the rabbit’s energy. This transfer of energy works by making those animals on the top of the food chain have a smaller population compared to the animals and plants below it because those on top only get a portion of the overall energy. This is the transfer of energy from one animal to another (Campbell, 1192)

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Biosphere
In the largest scale there is even an example of the transfer of energy. In a biosphere every animal and plant are in it. As you have seen in the previous examples much of energy transfer deals with the plant or animal that is eaten but originally all of these examples got energy from the sun. So over all everything is intertwined in the energy of the sun. The photons from the sun cause the plants to create the chemical form of energy for all animals. Without the sun or the original energy source most animals and plants would die. This is the transfer of energy to all of life (Campbell, 1192).

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Information Source
Campbell, Neil A. Reece, Jane. Biology. Beth Wilbur. 7^th edition. San Francisco: Benjamin Cummings, 2005.

This entry was posted on Wednesday, April 23rd, 2008 at 2:57 pm and is filed under AP Biology, Themes in Biology. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

2 Responses to “Themes in Biology - Energy Transfer”

Billy Says:
May 1st, 2008 at 1:18 pm
I did a little more research on the biosphere. The biosphere is the life zone of the Earth and includes all living organisms, including man, and all organic matter that has not yet decomposed. Life evolved on earth during its early history between 4.5 and 3.8 billion years ago and the biosphere readily distinguishes our planet from all others in the solar system. The chemical reactions of life (e.g., photosynthesis-respiration, carbonate precipitation, etc.) have also imparted a strong signal on the chemical composition of the atmosphere, transforming the atmosphere from reducing conditions to and oxidizing environment with free oxygen. The biosphere is structured into a hierarchy known as the food chain whereby all life is dependent upon the first tier (i.e. mainly the primary producers that are capable of photosynthesis). Energy and mass is transferred from one level of the food chain to the next with an efficiency of about 10%. All organisms are intrinsically linked to their physical environment and the relationship between an organism and its environment is the study of ecology. The biosphere can be divided into distinct ecosystems that represent the interactions between a group of organisms forming a trophic pyramid and the environment or habitat in which they live.
Website: http://www.geology.ufl.edu/Biosphere.htm
I don’t quite understand organismal. Could someone help explain it to me.
Grant T Says:
May 4th, 2008 at 11:57 am
Thanks Jacob, I really understand energy transfer a lot better now. I understand that energy is not created, nor destroyed, but it is TRANSFERED.

Energy can be transferred from one location to another, as in the sun’s energy travels through space to Earth. The two ways that energy can be transferred are by doing work and heat transfer. Energy can be transferred from one object to another by doing work. When work is done on an object, it results in a change in the object’s motion (more specifically, a change in the object’s kinetic energy).

Heat is given off when an object’s thermal energy is transferred. Thermal energy can be transferred in three ways: by conduction, by convection, and by radiation. Conduction is the transfer of energy from one molecule to another. This transfer occurs when molecules hit against each other, similar to a game of pool where one moving ball strikes another, causing the second to move. Conduction takes place in solids, liquids, and gases, but works best in materials that have simple molecules that are located close to each other. For example, metal is a better conductor than wood or plastic. Convection is the movement of heat by a liquid such as water or a gas such as air. The liquid or gas moves from one location to another, carrying heat along with it. This movement of a mass of heated water or air is called a current. Heat travels from the sun by a process called radiation. Radiation is the transfer of heat by electromagnetic waves. When infrared rays strike a material, the molecules in that material move faster. In addition to the sun, light bulbs, irons, and toasters radiate heat. When we feel heat around these items, however, we are feeling convection heat (warmed air molecules) rather than radiated heat since the heat waves strike and energize surrounding air molecules.

Themes in Biology - Energy Transfer

2 Responses to “Themes in Biology - Energy Transfer”

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