1. KEY CONCEPT Pyramids model the distribution of energy and matter in an ecosystem.

2. An energy pyramid shows the distribution of energy among trophic levels.
energy transferred
energy
lost
Energy pyramids compare energy used by producers and other organisms on trophic levels.
Between each tier of an energy pyramid, up to 90 percent of the energy is lost into the atmosphere as heat.
Only 10 percent of the energy at each tier is transferred from one trophic level to the next.

3. Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms.
Biomass is a measure of the total dry mass of organisms in a given area.
tertiary
consumers
secondary
primary
producers
75 g/m2
150g/m2
675g/m2
2000g/m2

4. A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem.
tertiary
consumers
secondary
primary
producers 5
5000
500,000
5,000,000
A vast number of producers are required to support even a few top level consumers.

5. Each level in a food chain contains less energy than the one below it because some energy is
Added to the system
Lost as heat
Consumed by carnivores
Incorporated into biomass

6. The term biomass refers to the total
Dry mass of the organisms in a given area
Unused material excreted as waste
Producer-to-consumer ratio
Mass of all living things on Earth

7. A diagram that shows how available energy is distributed among trophic levels in an ecosystem is called a(n)
Food pyramid
Pyramid of numbers
Food web
Energy pyramid

8. A biomass pyramid is a diagram that compares the
Masses of different organisms
Number of different organisms
Biomass of different trophic levels
Distribution of energy in trophic levels

9. A diagram that shows the numbers of individual organisms at each trophic level in an ecosystem is called a(n)
Biomass pyramid
Pyramid of numbers
Energy pyramid
Inverted pyramid