Transcript Notes #1
Environmental
Science
Chapter 3
Notes #1
Energy Flow in
Ecosystems
Producer – an organism that makes its own food
Also called an autotrophy “self-feeders”
Consumer – an organism that gets its food by eating
other organisms
Also called “heterotrophs”
In your group discuss the following 3 statements
Almost all organisms get their energy from the sun
Producers get their energy directly from the sun
Consumers get their energy indirectly from the sun
Energy Flow in
Ecosystems
Exception to the rule – Deep-water
organisms
No sunlight = No photosynthesis
Some bacteria make food from hydrogen
sulfate
H2SO4 escapes from cracks in the ocean
floor
The bacteria become the producers
Energy Flow in
Ecosystems
What Eats What…
Herbivore – plant eater
Consumers that eat only producers
Carnivore – meat eater
Consumers that only eat other consumers
Omnivores – plant + meat eater
“Eaters of all”
Decomposers – dead organisms
Get food by rotting dead organisms
Energy Flow in
Ecosystems
photosynthesis
6CO2 + 6H2O + light energy C6H12O6 + 6O2
Cellular Respiration
The process of breaking down food to yield
energy
Cellular respiration
C6H12O6 + 6O2 6CO2 + 6H2O + energy
If you look closely you can see that the two processes
are opposites of one another.
Energy Flow in
Ecosystems
Even organisms that use photosynthesis to
make food use cellular respiration to obtain
energy from the food.
All living organisms use cellular respiration to
obtain energy from food molecules
Every time one organism eats another
organism energy gets transferred…this transfer
can be traced thru food chains, food webs, and
trophic levels.
Energy Flow in
Ecosystems
Food Chains/Food Webs
Food Chain – a sequence in which energy is
transferred from one organism to another as
each organism eats another.
Ecosystems are more complicated than a
simple food chain.
Food Web - Shows many of the feeding
relationships in an ecosystem.
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Energy Flow in Ecosystems
Trophic levels
Shows each step in the transfer of
energy
Ex. The previous food chain
Algae – the bottom trophic level
Krill – the next up trophic level
Each time energy is transferred, less is
available to the organisms at the next
trophic level
Energy Flow in Ecosystems
This relationship can be shown with an energy
pyramid
Producers form the base of the pyramid (lowest level)
Herbivores = next level = primary consumers
Carnivores that eat herbivores = secondary
consumers
Carnivores that eat other carnivores= tertiary
consumer
Pyramids get smaller at the top, less energy at top
Energy loss results in fewer organisms at the higher
trophic levels
Energy Flow in Ecosystems