Energy flow is unidirectional
Energy moves one way.
A one-way road
Sunlight is captured by grass. A cow eats the grass.
Can the energy that has passed from the grass to the cow go back to the grass?
What this lesson covers
The idea
The flow of energy is unidirectional: energy captured by autotrophs does not revert to the solar input, energy passed to herbivores does not return to autotrophs, and energy moving up is no longer available to the previous level.
A one-way road
Sunlight is captured by grass. A cow eats the grass.
Can the energy that has passed from the grass to the cow go back to the grass?
- No, it moves one way
- Yes, whenever the grass needs it
- Yes, back to the Sun first
Follow the arrows
Press Next step.
A one-way flow
Energy captured by plants is passed to herbivores. It is not passed back to the plants, and it does not return to the Sun. As energy moves up the levels, it is no longer available to the level before.
The flow of energy is unidirectional: energy captured by autotrophs does not revert to the solar input, energy passed to herbivores does not return to autotrophs, and energy moving up is no longer available to the previous level.
Notes
Energy flows one way: it does not return to the Sun or to the plants.
Check yourself
The energy captured by the autotrophs ...
What does it mean that the flow of energy is unidirectional?
Which shows the direction in which energy flows in a food chain?
- goes back to the Sun when the plant dies. The book says that energy captured by autotrophs does not revert back to the solar input.
- does not revert back to the solar input — correct. Yes!
- stays in the producers and does not pass on. The energy passes from the autotrophs to the herbivores and the other organisms.
- Energy moves back and forth between producers and consumers. Energy passed to the herbivores does not come back to the autotrophs.
- The same amount of energy reaches each level. The energy available gets smaller at each trophic level.
- Energy moves in one direction and is no longer available to the previous level — correct. Yes!
- Sun to producers to herbivores to carnivores — correct. Yes!
- Carnivores to herbivores to producers to Sun. That is the opposite direction. Energy moves up from the Sun to the producers and then to the consumers.
- Herbivores to producers to carnivores. Energy passed to the herbivores does not return to the producers.