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1.10 Energy Flow and the 10% Rule

3 min readdecember 26, 2022

schuyler-fishman

schuyler-fishman

schuyler-fishman

schuyler-fishman

Solar energy provides every ecosystem with its energy supply, and as it moves through the from producer to herbivore to carnivore and then to decomposers, this solar energy becomes chemical. occurs when light is taken in by plants and converted into oxygen and food. Energy is stored in the glucose molecule which, through the chemical reactions of , is transformed again into and a new form of chemical energy (ATP) used by the cells. 

Nothing in the universe is perfect and energy transferrence is not entirely efficient. Since energy, like matter, cannot be created or destroyed, the energy is not “lost,” but instead changes into a less organized form. This means that ecosystems do not directly use all the energy provided, but rather lose it to dysfunction or assorted environmental processes. These laws are important in ecology because they explain the distribution and variety of biotic and abiotic factors in ecosystems.

The First Law of Thermodynamics

This is the law of conservation of energy. The law states that, in a closed system, energy cannot be created or destroyed, it can only be transformed from one form to another. Like the image below, 100kcal of ice cream should get you 100kcal of kinetic energy. So why doesn’t it work that way?

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-qWK0h9jVpjUe.JPG?alt=media&token=0ab6693c-c1e1-4d15-b0eb-c7c0c8dd4519

The Second Law of Thermodynamics

The states that increases every time energy is forced to reroute or change forms. is the amount of disorganization present in a system. has the most disorder, or the most . What you need to know is that energy transformations always result in losses to waste heat. In the case of organisms eating organisms, these losses result in only 10% of the energy (on average being passed onto the next trophic level. The of trophic levels, as a result, is quite high, due to the low rate of energy transfer per tier. It also explains why it is impossible to use an energy resource that is 100% efficient, which is something you will review in unit 6.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-Ytr8sjvlcPRi.JPG?alt=media&token=da069aa3-b5c2-4893-9b9d-c0f693d26ee4

The 10% Rule

The states that only 10% of energy from one trophic level is able to move up to the next. So, if producers have 10,000 J of energy stored through , then only 1000 J is passed on to . You can calculate the amount of energy up and down the pyramid by moving the decimal place to the left as you move up one trophic level, and to the right as you move back down. As a result, 90% of energy per tier is lost to waste heat. It is important to note that , on average, only captures 1% of the sun’s energy, while roughly 99% is lost to reflection or other miscellaneous systems. And not all ecosystems have a 10% efficiency, it depends on the type of biome. On average, though, 10% is an easy threshold to help understand why an individual jaguar needs at least one square mile to support enough vegetation to feed its prey

🎥 To learn more about trophic levels and the flow of energy, watch this stream.

Key Terms to Review (10)

10% Rule

: The 10% rule is a principle in ecology that states that only about 10% of the energy available at one trophic level is transferred to the next trophic level. This means that as you move up the food chain, only a small fraction of the energy from the lower trophic levels is passed on.

ATP (Adenosine Triphosphate)

: ATP is a molecule that stores and provides energy for cellular processes in living organisms. It is often referred to as the "energy currency" of cells.

Cellular Respiration

: Cellular respiration is the process by which cells convert glucose (sugar) into energy (ATP) through a series of chemical reactions. It occurs in both plants and animals and is essential for their survival.

Entropy

: Entropy is a measure of the disorder or randomness within a system. It quantifies how spread out or dispersed energy is within a given system. In simple terms, it represents the level of chaos or randomness in a system.

First Law of Thermodynamics

: The First Law of Thermodynamics, also known as the law of energy conservation, states that energy cannot be created or destroyed in an isolated system. It can only change forms or be transferred from one object to another.

Photosynthesis

: Photosynthesis is the process through which green plants use sunlight, carbon dioxide, and water to produce glucose (sugar) and oxygen. It is vital for plant growth and releases oxygen into the atmosphere.

Primary Consumers

: Primary consumers, also known as herbivores, are organisms that feed directly on producers (plants or algae) in an ecosystem. They obtain their energy by consuming plant material.

Second Law of Thermodynamics

: The Second Law of Thermodynamics states that in any natural process, the total entropy (disorder) always increases for an isolated system. This means that systems tend to move towards a state with higher randomness and less usable energy.

Thermal Energy

: Thermal energy refers to the total kinetic energy of all the particles in a substance. It is a measure of how fast the particles are moving and vibrating.

Trophic Pyramid

: A trophic pyramid represents the flow of energy through different trophic levels in an ecosystem. It shows how energy decreases as it moves up from producers to primary consumers, secondary consumers, and so on.

1.10 Energy Flow and the 10% Rule

3 min readdecember 26, 2022

schuyler-fishman

schuyler-fishman

schuyler-fishman

schuyler-fishman

Solar energy provides every ecosystem with its energy supply, and as it moves through the from producer to herbivore to carnivore and then to decomposers, this solar energy becomes chemical. occurs when light is taken in by plants and converted into oxygen and food. Energy is stored in the glucose molecule which, through the chemical reactions of , is transformed again into and a new form of chemical energy (ATP) used by the cells. 

Nothing in the universe is perfect and energy transferrence is not entirely efficient. Since energy, like matter, cannot be created or destroyed, the energy is not “lost,” but instead changes into a less organized form. This means that ecosystems do not directly use all the energy provided, but rather lose it to dysfunction or assorted environmental processes. These laws are important in ecology because they explain the distribution and variety of biotic and abiotic factors in ecosystems.

The First Law of Thermodynamics

This is the law of conservation of energy. The law states that, in a closed system, energy cannot be created or destroyed, it can only be transformed from one form to another. Like the image below, 100kcal of ice cream should get you 100kcal of kinetic energy. So why doesn’t it work that way?

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-qWK0h9jVpjUe.JPG?alt=media&token=0ab6693c-c1e1-4d15-b0eb-c7c0c8dd4519

The Second Law of Thermodynamics

The states that increases every time energy is forced to reroute or change forms. is the amount of disorganization present in a system. has the most disorder, or the most . What you need to know is that energy transformations always result in losses to waste heat. In the case of organisms eating organisms, these losses result in only 10% of the energy (on average being passed onto the next trophic level. The of trophic levels, as a result, is quite high, due to the low rate of energy transfer per tier. It also explains why it is impossible to use an energy resource that is 100% efficient, which is something you will review in unit 6.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-Ytr8sjvlcPRi.JPG?alt=media&token=da069aa3-b5c2-4893-9b9d-c0f693d26ee4

The 10% Rule

The states that only 10% of energy from one trophic level is able to move up to the next. So, if producers have 10,000 J of energy stored through , then only 1000 J is passed on to . You can calculate the amount of energy up and down the pyramid by moving the decimal place to the left as you move up one trophic level, and to the right as you move back down. As a result, 90% of energy per tier is lost to waste heat. It is important to note that , on average, only captures 1% of the sun’s energy, while roughly 99% is lost to reflection or other miscellaneous systems. And not all ecosystems have a 10% efficiency, it depends on the type of biome. On average, though, 10% is an easy threshold to help understand why an individual jaguar needs at least one square mile to support enough vegetation to feed its prey

🎥 To learn more about trophic levels and the flow of energy, watch this stream.

Key Terms to Review (10)

10% Rule

: The 10% rule is a principle in ecology that states that only about 10% of the energy available at one trophic level is transferred to the next trophic level. This means that as you move up the food chain, only a small fraction of the energy from the lower trophic levels is passed on.

ATP (Adenosine Triphosphate)

: ATP is a molecule that stores and provides energy for cellular processes in living organisms. It is often referred to as the "energy currency" of cells.

Cellular Respiration

: Cellular respiration is the process by which cells convert glucose (sugar) into energy (ATP) through a series of chemical reactions. It occurs in both plants and animals and is essential for their survival.

Entropy

: Entropy is a measure of the disorder or randomness within a system. It quantifies how spread out or dispersed energy is within a given system. In simple terms, it represents the level of chaos or randomness in a system.

First Law of Thermodynamics

: The First Law of Thermodynamics, also known as the law of energy conservation, states that energy cannot be created or destroyed in an isolated system. It can only change forms or be transferred from one object to another.

Photosynthesis

: Photosynthesis is the process through which green plants use sunlight, carbon dioxide, and water to produce glucose (sugar) and oxygen. It is vital for plant growth and releases oxygen into the atmosphere.

Primary Consumers

: Primary consumers, also known as herbivores, are organisms that feed directly on producers (plants or algae) in an ecosystem. They obtain their energy by consuming plant material.

Second Law of Thermodynamics

: The Second Law of Thermodynamics states that in any natural process, the total entropy (disorder) always increases for an isolated system. This means that systems tend to move towards a state with higher randomness and less usable energy.

Thermal Energy

: Thermal energy refers to the total kinetic energy of all the particles in a substance. It is a measure of how fast the particles are moving and vibrating.

Trophic Pyramid

: A trophic pyramid represents the flow of energy through different trophic levels in an ecosystem. It shows how energy decreases as it moves up from producers to primary consumers, secondary consumers, and so on.


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© 2024 Fiveable Inc. All rights reserved.

AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.