Energy Flow
Who eats what in an ecosystem?
 Ecosystems are structured by who eats
whom. A trophic level is the position that
an organism occupies in a food chainwhat it eats and what eats it. Every
organism belongs to at least one feeding
level or tropic level.
The trophic levels are:
 Producers make their own food through
photosynthesis or chemosynthesis
Examples: grass, fern, cactus, flowering
plant, tree, algae, some bacteria
Trophic Levels Cont.
 Consumers get their energy by eating producers
or other consumers.
Examples: mouse, starfish, turtle, paramecium,
sponge, ant, human
Trophic Levels Cont.
 Decomposers break down dead
organisms in an ecosystem and return
the nutrients to soil, water and air.
Converts bond energy from dead and
decaying organisms into heat.
Examples: fungus, bacteria,
earthworms & insects
Who can make their own food?
 Autotroph
auto means self
troph means nourish
 An organism that produce, or make their
own food. Autotrophs are also called
producers. (Plants & Algae)
 Heterotroph
 An organism that obtain its energy by the
consumption of other organisms.
 Heterotrophs are also called consumers.
Types of consumers in an ecosystem
 Primary Consumer – The first consumer
in a food chain/food web and consumes
a producer. Herbivores or plant eater
 Secondary Consumer – The second
consumer in a food chain/food web.
 Tertiary Consumer – The third
consumer in a food chain/food web.
carnivore or omnivore
Organisms Are Grouped by What They Consume
 Herbivore – An organism that eats
plants, nuts, berries ie. rabbit, deer
 Omnivore – An organism that eats
plants and animals ie. black bear,
human
 Carnivore – An organism that eats
animals ie. wolf, hawk, whale
Organisms Cont.
 Scavenger – An organism that feeds off of
dead animals that they did not hunt or kill
themselves. ie. vulture
 Decomposer – An organism which obtains its
energy from dead or decaying organisms, thus
returning nutrients into the soil ie. bacteria or
fungi
 Predator – An organism that feeds on what it
hunts and kills ie. coyote
 Prey – An organism that is hunted and
killed for food ie: mouse
 Food Chain – A pathway in which
energy flows through an ecosystem.
 Food Web – All possible pathways in
which energy flows through an
ecosystem.
Energy flow… how it begins
 Photosynthesis – Conversion of sun’s
energy to food energy
 6CO2 + 6H2O + Sunlight energy  C6H12O6 + 6O2
 (C6H12O6 = food energy, chemical energy, potential
energy - in bonds)
Energy flow…
 Cellular respiration
 Process by which chemical bonds (food
energy) are converted to usable energy.
 C6H12O6 + 6O2  6CO2 + 6H2O + ATP
(usable energy for
cells)
Energy flow… how it begins
 Photosynthesis – Conversion of sun’s
energy to food energy
 6CO2 + 6H2O + Sunlight energy  C6H12O6 + 6O2
 (C6H12O6 = food energy, chemical energy, potential
energy - in bonds)
Energy flow…
 Cellular respiration
 Process by which chemical bonds (food
energy) are converted to usable energy.
 C6H12O6 + 6O2  6CO2 + 6H2O + ATP
(usable energy for
cells)