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Energy*# - Biology

Energy*# - Biology



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Energy is a central concept in all sciences. In class, many of the discussions will happen in the context of the Energy Story rubric, so when we consider a reaction of transformation, we will be interested in precisely defining the system in question and trying to account for all the various transfers of energy that occur within the system, making sure that we abide by the Law of Conservation of Energy.

There are plenty of examples where we use the concept of energy in our everyday lives to describe processes. A bicyclist can bike to get to campus for class. The act of moving herself and her bicycle from point A to point B can be explained to some degree by examining the transfers energy that take place. We can look at this example through a variety of lenses, but, as biologists, we more than likely want to understand the series of events that explain how energy is transferred from molecules of food, to the coordinated activity of biomolecules in a bicyclist's flexing muscle, and finally, to the motion of the bike from point A to point B. To do this, we need to be able to talk about various ways in which energy can be transferred between parts of a system and where it is stored or transferred out of the system. In the next section, we will also see the need to consider how that energy is distributed among the many microstates (molecular states) of the system and its surroundings.

How we will approach conceptualizing energy

In BIS2A we will think about energy with a "stuff" metaphor. Note, however, that energy is NOT a substance, it is rather a property of a system. But we will think of it, in some sense, as property that can be stored in a part of a physical system and transferred or "moved" from one storage place to another. The idea is to reinforce the idea that energy maintains its identity when transferred—it is not changing forms per se. This in turn also encourages us to make sure that energy always has a home and that we account for all of the energy in a system before and after a transformation; it does not just "made" or get "lost" (both ideas contradict of the Law of Conservation of Energy). When energy is being transferred, we therefore must identify where it is coming from and where it is going—all of it! Again, we can't just have some getting lost. When energy is transferred, there must be some mechanism associated with that transfer. Let's think about that to help us explain some of the phenomena we're interested in. That mechanism is part of the "how" that we are often interested in understanding. Finally, if we talk about transfer, we must realize that both components, the part of the physical system that gave up energy and the part of the system that received that energy, are changed from their initial states. We should make sure that we are looking at all of the components of a system for changes in energy when examining a transformation.

Energy sources

Ultimately, the source of energy for many processes occurring on the Earth's surface comes from solar radiation. But as we will see, biology has been very clever at tapping a variety of forms of energy to construct and maintain living beings. As we move through this course, we will explore a variety of energy sources and the ways in which biology has devised to transfer energy from these fuels.


Energy

Definition
noun, plural: energies
(1) The capacity for work.
(2) The ability to do work, or produce change.
Supplement
Energy exists in different forms but is neither created nor destroyed it simply converts to another form. Examples of energy include: kinetic, potential, thermal, gravitational, elastic, electromagnetic, chemical, nuclear, and mass. Energy can be expressed in joules or ergs
In biology, energy is often stored by cells in biomolecules, like carbohydrates (sugars) and lipids. The energy is released when these molecules have been oxidized during cellular respiration. The energy released from them when they are oxidized during cellular respiration is carried and transported by an energy-carrier molecule called ATP.
Word origin: From Ancient Greek ἐνέργεια (energeia) “action, act, work”, < ἐνεργός (energos) “active” < ἐν (en) “in” + ἔργον (ergon) “work”.
Related forms: energize (verb), energetic (adjective).

Related phrases: kinetic energy, potential energy, solar energy.

Last updated on March 5th, 2021


Fast Facts

  • Systems biology studies of the genomes of soil-dwelling microbes discovered that they are also infected by thousands of different viruses that affect how they modify carbon-rich organic material.
  • Comparing the decoded genomes of different plants helps us understand how plants sequester carbon dioxide and store carbon in cellulose and other polymers that constitute the plant body.
  • Baker’s yeasts are used to make ethanol not only for beer but also as a biofuel. Understanding their systems biology allows scientists to engineer new yeast strains that can one day produce a replacement for gasoline.

Potential and Kinetic Energy

When an object is in motion, there is energy associated with that object. Think of a wrecking ball. Even a slow-moving wrecking ball can do a great deal of damage to other objects. Energy associated with objects in motion is called kinetic energy (Figure 4). A speeding bullet, a walking person, and the rapid movement of molecules in the air (which produces heat) all have kinetic energy.

Figure 4. Still water has potential energy moving water, such as in a waterfall or a rapidly flowing river, has kinetic energy. (credit “dam”: modification of work by “Pascal”/Flickr credit “waterfall”: modification of work by Frank Gualtieri)

Now what if that same motionless wrecking ball is lifted two stories above ground with a crane? If the suspended wrecking ball is unmoving, is there energy associated with it? The answer is yes. The energy that was required to lift the wrecking ball did not disappear, but is now stored in the wrecking ball by virtue of its position and the force of gravity acting on it. This type of energy is called potential energy (Figure 4). If the ball were to fall, the potential energy would be transformed into kinetic energy until all of the potential energy was exhausted when the ball rested on the ground. Wrecking balls also swing like a pendulum through the swing, there is a constant change of potential energy (highest at the top of the swing) to kinetic energy (highest at the bottom of the swing). 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 is not only associated with the location of matter, but also with the structure of matter. Even a spring on the ground has potential energy if it is compressed so does a rubber band that is pulled taut. On a molecular level, the bonds that hold the atoms of molecules together exist in a particular structure that has potential energy. Remember that anabolic cellular pathways require energy to synthesize complex molecules from simpler ones and catabolic pathways release energy when complex molecules are broken down. The fact that energy can be released by the breakdown of certain chemical bonds implies that those bonds have potential energy. In fact, there is potential energy stored within the bonds of all the food molecules we eat, which is eventually harnessed for use. This is because these bonds can release energy when broken. The type of potential energy that exists within chemical bonds, and is released when those bonds are broken, is called chemical energy. Chemical energy is responsible for providing living cells with energy from food. The release of energy occurs when the molecular bonds within food molecules are broken.

Concept in Action


For Students & Teachers

For Teachers Only

ENDURING UNDERSTANDING
ENE-1
The highly complex organization of living systems requires constant input of energy and the exchange of macromolecules.

LEARNING OBJECTIVE
ENE-1.H
Describe the role of energy in living organisms.

ESSENTIAL KNOWLEDGE
ENE-1.H.1
All living systems require constant input of energy.

ENE-1.H.2
Life requires a highly ordered system and does not violate the second law of thermodynamics–

  1. Energy input must exceed energy loss to maintain order and to power cellular processes.
  2. Cellular processes that release energy may be coupled with cellular processes that require energy.
  3. Loss of order or energy flow results in death.

ENE-1.H.3
Energy-related pathways in biological systems are sequential to allow for a more controlled and efficient transfer of energy. A product of a reaction in a metabolic pathway is generally the reactant for the subsequent step in the pathway.

EXCLUSION STATEMENT
Students will need to understand the concept of energy, but the equation for Gibbs free energy is beyond the scope of the course and AP Exam.


Energy

power, force, energy, strength, might mean the ability to exert effort. power may imply latent or exerted physical, mental, or spiritual ability to act or be acted upon. the awesome power of flowing water force implies the actual effective exercise of power. used enough force to push the door open energy applies to power expended or capable of being transformed into work. a worker with boundless energy strength applies to the quality or property of a person or thing that makes possible the exertion of force or the withstanding of strain, pressure, or attack. use weight training to build your strength might implies great or overwhelming power or strength. the belief that might makes right


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Get notified when we have news, courses, or events of interest to you.

By entering your email, you consent to receive communications from Penn State Extension. View our privacy policy.

Thank you for your submission!

Penn State Digester Day

Workshops

Anaerobic Digestion: Biogas Production and Odor Reduction

Articles

Applied Biogas Technology: Converting Organic Waste to Energy

Online Courses

Biochar Enhanced Infiltration Basin in Central Pennsylvania

Articles

Manufacturing Fuel Pellets from Biomass

Articles

Biology and Renewable Energy

When people talk about renewable energy, they usually refer to solar, wind and geothermal sources. These are generally the domain of physical mechanical processes that have no reliance upon any living organisms. As a result, students who wish to work in this field typically enter Engineering and the Physical Sciences.

But what if the life sciences could also play a role in the new energy paradigm? Enter the fascinating world of bioenergy.

Most vehicles run on petroleum-based fuels, whether it be the cars on the road or the planes in the sky. Not only is this toxic for the environment, but it can also create a variety of economic and trade issues. And worst of all, there is only a limited supply of them in the ground.

But what if we could obtain our fuel from a renewable resource instead?

Biodiesel ​is the answer to this.​ ​Biodiesel is oil that is derived from organic matter. Typically, this is the fats and oils found in crops and (very rarely) meat. Biodiesel is produced by chemically reacting lipids (such as vegetable and soybean oil) with alcohol. Biodiesel is commonly mixed with regular petroleum to bring down the average lifecycle emission levels of the fuel. One drawback of biodiesel is that if it is a low-quality variant or too much is used then the engine can be damaged.

If you think that getting gasoline from food sounds delicious, then you’re in for a treat. It turns out that corn or other sugar-based crops can also be turned into a fuel! Through a complex process of milling, mashing, and fermenting in industrial facilities, an energy dense substance known as ​Ethanol ​can be made.

One of the most popular applications of ethanol is in serving as a vehicle fuel. Ethanol from ethanol stations is typically not pure ethanol (since that would be too corrosive) but ​E-85​, which is a mixture of 85% ethanol and 15% petroleum, is three quarters as energy dense than petroleum. This means that you would have to burn four cans of E-85 to get the energy equivalent of three cans of petroleum (check out ​U.S. Energy Information Administration – EIA – Independent Statistics and Analysis for more details). Despite this, ethanol emits much less pollution into the atmosphere and runs much cleaner in the engine.

A vehicle’s engine needs to be modified to run on ethanol. Around 87% of vehicles in Brazil (an important country for ethanol production) and 7% in the United States have this upgrade. Vehicles that are ready for ethanol are known as “Flexfuel” vehicles.

Algae Bioenergy

What if you like the idea of getting energy from a food crop but you’re not the biggest fan of Ethanol? After all, growing crops such as corn can take a long time and use up a lot of water. Luckily for you there is an answer in the form of ​Algae Bioenergy.

Algae is a category for rootless, stemless, leafless (and usually unicellular) microorganisms that obtain their energy from photosynthesis. This makes them completely renewable and even offers the potential to sequester carbon dioxide. Algae can begin as a single cell organism and can then be grown out in aquatic raceways, drained and pulled out when the time comes for energy extraction. This dried Algae can then be transformed into oil, making it useful as a fuel. What makes Algae so unique is that not only can it be used in an internal combustion engine without having to modify the engine but the fact that growing algae takes carbon out of the atmosphere can make Algae somewhat of a carbon negative fuel!

Bioenergy Metrics

Although there are many different sources of bioenergy, we need some way to measure how effective they are. We can do this using something called ​Bioenergy Metrics. The most basic metrics focus on the productivity of the feedstocks. ​Primary Productivity ​is the actual rate at which plants store energy, the ​Gross Primary Productivity ​is the summation of all photosynthetic activity, and the ​Total Primary Productivity ​is the net transfer of carbon from the atmosphere into green plants per unit time (basically how much useful net energy is created by ecosystem plants in a given time).

Final Thoughts

Biological feedstocks can play an important role in renewable energy. Whether it be from the corn we eat or the algae we see in the aquarium, there are novel sources of energy that can be found anywhere. All it takes is a little bit of scientific knowledge and engineering ingenuity.

Recommended Reading:

U.S. Energy Information Administration – EIA – Independent Statistics and Analysis. ​ Few Transportation Fuels Surpass the Energy Densities of Gasoline and Diesel – Today in Energy – U.S. Energy Information Administration (EIA), U.S Energy Information Administration, 13 Feb. 2013, www.eia.gov/todayinenergy/detail.php?id=9991#.

Emerging Topics in Life Sciences – Adapting to Climate Change: People and Biology http://www.emergtoplifesci.org/content/3/2

About the Author

I am a soon to be graduating undergraduate student in Mechanical Engineering and Mathematics at San José State University in California. I am interested in pursuing graduate school and consulting opportunities related to renewable energy and sustainability. In my spare time, I like to write on my daily science blog and learn other languages. Feel free to reach out to me on LinkedIn and Twitter..