1. How Ecosystems Work
Ch. 5, Section 1: Energy Flow in
Ecosystems
Standards: SEV1a, d, e, SEV3a, b, c

2. What’s sun got to do with it, got to do
with it…?
• Energy from sun helps
plants/algae make
carbohydrate food molecules
through PHOTOSYNTHESIS.
• Ingredients:
–
–
–
–
CO2 (from the air)
H2O (from soil)
Sunlight provides the energy
These CO2 and H2O molecules
are broken and reformed as
C6H12O6 which is glucose.
• This carbohydrate food from
plants/algae is the base of all
food chains.

3. An Exception to the Rule:
Deep Ocean Ecosystems
• Hydrothermal vents located
at the bottom of the ocean
off coast of Ecuador.
• These ecosystems do not get
sunlight= no plants/algae
• What is the base of the food
chain?
• Specialized bacteria are able
to take sulfur from water
surrounding vent and turn it
into food.
• These bacteria are the base
of the food chain in this
ecosystem.

4. How do organisms get energy from
food they eat?
• Plants & animals break down this
carbohydrate food and release
energy from the molecules via
CELLULAR RESPIRATION.
• C6H12O6 (glucose) is broken down
using oxygen that was “breathed”
in and creates ATP energy and CO2.
• ATP energy is used for everyday
activities, growth, development, et
c.
• Plants & animals are
interdependent on each other.
– Plants give animals the O2 and food.
– Animals give plants the CO2 to make
the food.

5. What are the different types of
organisms in an ecosystem?
• Producers
–
–
–
–
–
AKA: autotroph
“Auto”- self
“Troph”- feeder
Make their own food
Ex: plants & algae
• Consumers
–
–
–
–
AKA: heterotroph
“Hetero”- other
“Troph”- feeder
Must consume other
organisms to get energy
– Ex: animals, most
bacteria, fungi

6. What are the different types of
consumers/heterotrophs?
• Herbivores
– Energy source: plants
– Example: cows, deer
• Carnivores
– Energy source: other
consumers
– Example: lion, snake
• Omnivores
– Energy source: producers
& consumers
– Example: bear, rat, human

7. What are the different types of
consumers/heterotrophs?
• Decomposers
– Energy source: break down
and ABSORB nutrients thru cell
wall
– Example: bacteria, fungi
• Scavengers
– Energy source: eat dead/
decomposing material with
mouth; LARGER organisms
– Example: vulture; hyena
• Detritivores
– Energy source: eat
dead/decomposing material
with mouth; SMALLER
organisms
– Example: worm, roly poly

8. How is energy transferred through an
ecosystem?
• Food chains, Food
webs, & trophic levels can
tell us
– how energy is transferred
– how much energy is
transferred between
organisms
• These also show which
organisms are dependent
on others for survival.

9. What are trophic levels?
• Trophic levels are the steps
through which energy is
transferred from one
organism to the next.
• 90% of the energy
consumed by an organism…
– Is used up by that organism to
grow & develop
– Is lost from that organism as
heat & waste
• 10% of the energy is stored
in its tissues and can be
passed to another animal
when it gets eaten.
Yellow arrows show release of heat
Orange arrows show release of waste
(feces)
Red pyramid shows only 10% of the level
below is transferred upward.
(10% of 10,000 = 1,000)

10. What are trophic levels?
• Primary Producersplants/algae
• Primary Consumers- get
energy from producers
(herbivore)
• Secondary Consumers- get
energy from primary
consumers (carnivores)
• Tertiary consumers- get
energy from secondary
consumers
(carnivores/omnivores)
• Quaternary consumers- get
energy from tertiary
consumers
(carnivores/omnivores)

11. How is a food chain different from a
food web?
• Food chains show ONE
set of relationships in
an ecosystem.
• Arrows show TRANSFER
OF ENERGY not who
eats who.
• Say to yourself, “The
energy from the bigger
fish goes into the killer
whale.”

12. How is a food chain different from a
food web?
• Food webs show
NUMEROUS
relationships in an
ecosystem.
• Food webs are more
detailed and show that
usually an organism
relies on more than one
source of food.

13. What can an energy pyramid tell us?
• A way to visualize the loss
of energy from one
trophic level to the next.
• Each level of pyramid
represents a trophic level.
• Show that most energy is
located at the bottom of
the pyramid (producers)
and less energy is
available to the top
consumers.

14. How does energy loss affect an
ecosystem?
• Less energy affects the
organization of an
ecosystem.
• Because energy is
lost, there are fewer
organisms as you go up
the pyramid.
• Also, there are limited
numbers of trophic levels
because of loss of energy.
Not enough energy to
support more than 3-5
trophic levels.

15. Ask yourself…
• What would happen to
the rodents if there was
more than one owl in
this ecosystem?
• What would then
happen to the
grasshopper
population?
• What would then
happen to the producer
population?