Energy flow
Energy flow
- The Sun is the main energy source for almost all life.
- Plants capture light by photosynthesis and store it as chemical energy in food.
- This energy passes from organism to organism as they feed.
Practice
The main source of energy for almost all ecosystems is:
Plants capture the Sun's light by photosynthesis; this energy then flows through the ecosystem.
Energy is lost and never recycled
- At every step, some energy is lost — mostly as heat from respiration.
- Energy flows one way through an ecosystem; it is not recycled (unlike nutrients).
Practice
At each step of a food chain, most energy is lost as:
Respiration releases much of the energy as heat, so less passes to the next level.
Practice
Energy flows one way through an ecosystem and is not recycled.
Energy enters from the Sun and is lost as heat — it flows one way; only nutrients are recycled.
You've got it
Key idea
- energy starts at the Sun, captured by photosynthesis, and passes along as organisms feed
- some is lost as heat (respiration) at every step
- energy flows one way and is not recycled