Introduction to Energy - Online Tutor, Practice Problems & Exam Prep

Energy, defined as the ability to perform work, exists in two main forms: potential energy, which is stored energy (e.g., gravitational and chemical potential energy), and kinetic energy, the energy of motion. In thermodynamics, the system refers to the matter being studied, while the surroundings encompass everything else. Biological systems, like plants, can exchange energy and mass with their surroundings, exemplified by photosynthesis, where solar energy and carbon dioxide enter the system, producing glucose and oxygen as outputs.

Introduction to Energy

In this video, we're going to begin our introduction to energy. Energy is defined as the ability to perform work. This term "work" can take on many different meanings, but it's not referring to your homework in this sense. Specifically, in biology, work refers to the transfer of energy that causes an overall change. Thus, energy can be defined as the ability to perform an overall change in a living system. In our course, we are going to discuss two different types of energy: potential energy and kinetic energy.

Potential energy is defined as energy that has potential. It is stored energy, available to do work or cause an overall change. The second type of energy, kinetic energy, is the energy of motion. Any substance that is moving or is in motion will have kinetic energy. Let's examine the image below to distinguish between these two types of energy.

Notice on the left-hand side, we have a chart where we list energy types in the left-hand column, including potential energy, the storage form of energy, and kinetic energy, the energy of motion, along with examples of each of these types. Starting with potential energy, there are different ways to store energy. One example of potential energy that is stored is gravitational potential energy. Gravitational potential energy occurs when an object is quite high relative to a gravitational force. For example, a biker at the top of a hill, as shown in these images, is not moving but still has high gravitational potential energy.

Another type of potential energy, or stored energy, is chemical potential energy. Chemical potential energy is when energy is stored in chemical bonds. A classic example of a molecule that has chemical potential energy is glucose, the most abundant and common sugar.

Regarding kinetic energy, the energy of motion, all moving objects will have kinetic energy. This includes a biker who is coasting or moving quickly down a hill, and muscle contractions. When you flex your bicep or get up to get a glass of water, those muscle contractions are considered a type of kinetic energy.

Now, looking at this other image on the right-hand side, it also helps to distinguish between potential and kinetic energy. A biker at the top of a hill, even though not moving, will have high gravitational potential energy. However, as soon as the biker starts coasting downhill due to gravity, the potential energy is converted into kinetic energy. By the time the biker reaches the bottom of the hill, the gravitational potential energy becomes low because the biker is no longer at the top.

This concludes our introduction to the two main types of energy that we will discuss moving forward: potential energy and kinetic energy. We will have some practice in our next couple of videos. I'll see you guys there.

Which of the following is an example of potential energy?

a) Water rushing over a water fall.

b) A glucose molecule.

c) A spring being released and expanding rapidly.

d) An ant foraging (moving around) for food.

• A. Water rushing over a water fall.
• B. A glucose molecule.
• C. A spring being released and expanding rapidly.
• D. An ant foraging (moving around) for food.

Which of the following is NOT a form of kinetic energy?

a) When the temperature of a substance rises causing the molecules of that substance to move faster.

b) When a hockey puck slides across the ice after being hit by a player.

c) When glucose molecules are broken down to create energy for cellular work.

d) When the molecules of the air vibrate transmitting soundwaves.

• A. When the temperature of a substance rises causing the molecules of that substance to move faster.
• B. When a hockey puck slides across the ice after being hit by a player.
• C. When glucose molecules are broken down to create energy for cellular work.
• D. When the molecules of the air vibrate transmitting soundwaves.

Thermodynamics:System vs. Surroundings

In this video, we're going to introduce thermodynamics and distinguish between the system and the surroundings. Thermodynamics is the study of energy transfers between different bodies of matter. It's crucial in the study of thermodynamics to distinguish between the system and the surroundings. The system is defined as the specific portion of matter that's being studied. Depending on the scenario, the system can change drastically. In some scenarios, the system will be an entire living organism, and in other scenarios, the system will be just a single specific reaction. The system will be any specific portion of matter that is the main focus of the study. Then, of course, the surroundings are pretty much just the surroundings that revolve or surround the system. So, everything else that's on the outside of the system will be part of the surroundings.

Biological systems are very interesting because they actually transfer both energy and mass with the surroundings. Let's take a look at our image down below to clear up this idea. Notice that in this particular scenario, the biological system is this plant that we have here in the middle. The biological system, this plant, is capable of allowing energy to enter the system, but it's also capable of allowing mass to enter the system. You can see that the solar energy from the sun is capable of entering the biological system, entering into the plant. But also, components that have mass, such as carbon dioxide gas and water molecules, are also capable of entering the biological system. It's important to note that not only can energy and mass enter the system, but they can also exit the system as well. You can see that energy is capable of entering the system, but then also exiting the system in a different form. Mass is also capable of entering the system but also exiting the system in a different form.

This biological system is a plant and it's capable of performing photosynthesis, and that's really what we're showing you here on this page. We'll talk a lot more about photosynthesis later in our course as we move forward. Basically, what you can see here is solar energy is capable of entering, mass such as carbon dioxide and water are capable of entering the biological system, and then what ends up coming out of the biological system is glucose, which is a sugar and is the most abundant sugar that exists. Recall from our last lesson video that glucose is a common form of chemical potential energy because all of these bonds that are formed in glucose contain chemical potential energy. It's a form of energy that's exiting the system here. Then also, oxygen gas is a form of mass that's exiting the system. The main takeaway here is that biological systems are capable of allowing energy and mass to enter the system, but also, energy and mass can also exit the system in different forms.

This concludes our introduction to thermodynamics and the distinguishing between the system and the surroundings, and we'll be able to get some practice applying these concepts as we move forward in our course. See you all in our next video.

Why are the principles of thermodynamics important for the study of biology?

a) The principles of thermodynamics govern the chemical processes in all biological organisms.

b) The principles of thermodynamics govern how an organism exchanges energy with their environment.

c) The principles of thermodynamics govern how all life on Earth exchanges energy.

d) All of the above.

• A. The principles of thermodynamics govern the chemical processes in all biological organisms.
• B. The principles of thermodynamics govern how an organism exchanges energy with their environment.
• C. The principles of thermodynamics govern how all life on Earth exchanges energy.
• D. All of the above.

Which of the following is NOT an example of a biological system?

a) A human eating a cheeseburger.

b) A coral reef where energy and mass both enter and exit.

c) The digestive system of an organism absorbing food energy and discarding food waste.

d) The universe where the amount of energy and mass is constant.

• A. A human eating a cheeseburger.
• B. A coral reef where energy and mass both enter and exit.
• C. The digestive system of an organism absorbing food energy and discarding food waste.
• D. The universe where the amount of energy and mass is constant.

Here’s what students ask on this topic:

What is the difference between potential energy and kinetic energy?

Potential energy is stored energy that has the potential to do work or cause change. Examples include gravitational potential energy, like a biker at the top of a hill, and chemical potential energy, such as the energy stored in glucose bonds. Kinetic energy, on the other hand, is the energy of motion. Any moving object, like a biker coasting down a hill or muscle contractions, possesses kinetic energy. Essentially, potential energy can be converted into kinetic energy when the stored energy is put into motion.

How do biological systems exchange energy and mass with their surroundings?

Biological systems, such as plants, can exchange both energy and mass with their surroundings. For example, during photosynthesis, solar energy and carbon dioxide enter the plant (the system). Inside the plant, these inputs are converted into glucose and oxygen, which then exit the system. This process demonstrates how energy and mass can enter and leave a biological system in different forms, facilitating various biological functions.

What is thermodynamics and how does it relate to biological systems?

Thermodynamics is the study of energy transfers between different bodies of matter. In biological systems, thermodynamics helps us understand how energy and mass are exchanged between the system (e.g., a plant) and its surroundings. For instance, in photosynthesis, solar energy and carbon dioxide enter the plant, and glucose and oxygen are produced and released. This exchange is crucial for understanding energy flow and transformations in living organisms.

What are some examples of potential energy in biological systems?

In biological systems, potential energy can be found in various forms. Gravitational potential energy is seen in objects positioned at a height, like a biker at the top of a hill. Chemical potential energy is stored in the bonds of molecules, such as glucose, which is a common sugar in biological systems. These forms of potential energy can be converted into kinetic energy to perform work or cause changes within the system.

How does photosynthesis demonstrate the principles of thermodynamics?

Photosynthesis exemplifies thermodynamics by showing how energy and mass are transferred and transformed within a biological system. Solar energy and carbon dioxide enter the plant (the system), where they are converted into glucose and oxygen. This process illustrates the first law of thermodynamics, which states that energy cannot be created or destroyed, only transformed. It also highlights the exchange of mass and energy between the system and its surroundings.