APES 1.9 and 1.10: Trophic Levels and the 10% Rule

What do all ecosystems depend on to maintain the flow of matter between the environment and organisms?

A continuous inflow of high-productivity energy

How does energy flow in terrestrial and near-surface marine communities?

From the sun to producers in the lowest trophic levels and then upward to higher trophic levels.

How much energy gets passed from one trophic level to the next?

10%

What explains the loss of energy between trophic levels?

Laws of thermodynamics

1st law of thermodynamics

energy is never created or destroyed

2nd law of thermodynamics

Entropy, or chaos, of an isolated system always increases

What does the 2nd law of thermodynamics mean in the context of trophic levels?

each time energy is transferred, some of it is lost to heat (the law basically says that hot things will move to cooler areas)

Unit for energy

joules

When comparing biomass as you go up one trophic level, how much is conserved?

10%

Unit for biomass

kg