Introduction to Energy: Videos & Practice Problems

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

Energy is fundamentally defined as the ability to perform work, which in biological contexts refers to the transfer of energy that results in an overall change within a living system. In this exploration of energy, two primary types are essential: potential energy and kinetic energy.

Potential energy is the stored energy that has the capacity to do work or induce change. A common example is gravitational potential energy, which is the energy an object possesses due to its position in a gravitational field. For instance, a biker at the top of a hill has high gravitational potential energy, even when stationary. Another form of potential energy is chemical potential energy, which is stored in the bonds of molecules. Glucose, a prevalent sugar, is a classic example of a substance with significant chemical potential energy.

On the other hand, kinetic energy is defined as the energy of motion. Any object that is moving possesses kinetic energy. For example, a biker coasting down a hill or the muscle contractions involved in physical activities, such as flexing a bicep, are manifestations of kinetic energy. As the biker descends the hill, the gravitational potential energy is converted into kinetic energy, illustrating the dynamic interplay between these two forms of energy.

In summary, understanding the distinction between potential energy, which is stored and ready to be converted into work, and kinetic energy, which is actively in motion, is crucial for grasping the principles of energy in biological systems. This foundational knowledge will be built upon in subsequent lessons, where practical applications and deeper insights into energy transformations will be explored.

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.

Answer: (B)

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.

Answer: (C)

Thermodynamics:System vs. Surroundings

Thermodynamics is the study of energy transfers between different bodies of matter, and understanding the distinction between the system and the surroundings is crucial in this field. The system refers to the specific portion of matter being studied, which can vary significantly depending on the context. For instance, a system could be an entire living organism or a single chemical reaction. In contrast, the surroundings encompass everything outside the system.

Biological systems are particularly fascinating because they can transfer both energy and mass with their surroundings. For example, consider a plant as a biological system. It can absorb solar energy and essential components like carbon dioxide and water from its surroundings. This energy and mass can also exit the system in different forms. During the process of photosynthesis, the plant takes in solar energy, carbon dioxide, and water, and produces glucose and oxygen. Glucose, a common form of chemical potential energy, is formed through the bonds created during this process, while oxygen is released as a byproduct.

In summary, biological systems like plants demonstrate the dynamic exchange of energy and mass with their surroundings, highlighting the principles of thermodynamics. This foundational understanding will be essential as we explore more complex concepts in the course.

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.

Answer: (D)

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.

Answer: (D)

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.