Lesson Overview
Objectives 3.3
Energy Flow in
Ecosystems
Energy Flow in Ecosystems
-Trace the flow of
energy through living
systems.
-Identify the three
types of ecological
pyramids.
Lesson Overview
Energy Flow in Ecosystems
Food Chains
A food chain is a series of steps in
which organisms transfer energy by
eating and being eaten.
Lesson Overview
Energy Flow in Ecosystems
Food Webs
In most ecosystems, feeding relationships are much more
complicated than the relationships described in a single
chain because many animals eat more than one kind of food.
Ecologists call this network of feeding interactions a food
web.
Lesson Overview
Energy Flow in Ecosystems
Trophic Levels
Each step in a food
chain or food web is
called a trophic level.
Primary producers
always make up the
first trophic level.
Various consumers
occupy every other level.
Lesson Overview
Energy Flow in Ecosystems
Ecological Pyramids
Ecological pyramids show the relative amount of
energy contained within each trophic level.
The different types of ecological pyramids are
pyramids of energy and pyramids of biomass.
Lesson Overview
Energy Flow in Ecosystems
Pyramids of Energy
What limits the number of trophic levels is
the amount of energy being passed on.
Only ~10% of the energy available within
one trophic level is transferred to the
next trophic level.
Lesson Overview
Energy Flow in Ecosystems
Pyramids of Biomass
The total amount of living tissue within a given
trophic level is called its biomass.
A pyramid of biomass illustrates the relative
amount of living organic matter at each trophic
level.
Lesson Overview
Energy Flow in Ecosystems
True or False
1.) The passage of energy from one organism to another
according to a particular feeding sequence is called a
food chain. _________________________
2.) In an ecological pyramid, the biomass of living things
increases at each higher level.
_________________________
3.) Only about 10 percent of the energy in a trophic
level is available to organisms at the next trophic
level. _________________________
Lesson Overview
Energy Flow in Ecosystems
False
1.) The passage of energy from one organism to another
according to a particular feeding sequence is called a
food chain.True
2.) In an ecological pyramid, the biomass of living things
increases at each higher level. False, decreases
3.) Only about 10 percent of the energy in a trophic
level is available to organisms at the next trophic
level. True