1. Section #1: Energy Flow in Ecosystems
How Ecosystems Work
Section #1:
Energy Flow in Ecosystems

2. Producers vs. Consumers
Characteristics
make their own food
capture energy from the sun
photosynthesis
green – contain chlorophyll
a.k.a. autotrophs (which means self-feeders)
all plants + some weird bacteria
Characteristics
can’t make own food
gain energy indirectly from the sun by eating other organisms (a producer or other consumer)
a.k.a. heterotrophs (which means other-feeders)

3. 4 Types of Consumers Herbivores only eat producers (like plants)
cows, sheep, mice, rabbits, deer, goats moose, beavers, grasshoppers, etc.
Carnivores
eat any type of consumer
hawk, snake, polar bears, foxes, spiders, lions, alligators, etc.
Omnivores
eat both producers & consumers
humans, monkeys, squirrels, raccoons, turtles, birds, fish & whales, amoebas, etc.
Decomposers
gains energy by breaking down dead organisms
mushrooms & other fungi, mold& other bacteria, etc.

4. How do organisms use the energy they get?
Cellular Respiration
the process of breaking down food to yield energy
occurs within the cell
cells absorb oxygen where it chemically combines with glucose (C6H12O6) to produce carbon dioxide, water and energy
done by all producers & consumers
any excess energy is stored as sugar or fat

5. How do Scientists Map the Movement of Energy in an Ecosystem?

6. Food Chain
a sequence in which energy is transferred from one organism to the next as each organism eats another organism
shown in a linear chain
most food chains have no more than four or five links
the further along the food chain you go, the less food (and hence energy) remains available
a change in the size of one population in a food chain will affect other populations

7. How do Scientists Map the Movement of Energy in an Ecosystem?

8. Food Web
energy flow is more complicated than a single food chain which is a single strand within a web
webs show the interconnections between the chains
shows that many feeding relationships are possible within an ecosystem because organisms do not eat just one other type of organism
Create your own food web using the following web site

9. Trophic Levels a step in the food chain or food web
energy moves from one trophic level to the next
each time energy is transferred from one organism to another, some energy is lost as heat
the next trophic level will have less energy to use

10. Lost Energy
whatever energy is available is used by the organism to carry out the functions of life
respiration
producing new cells
regulating body temperature
moving around
90% of the energy at each trophic level is used for these functions

11. Lost Energy that leaves 10% of the energy remaining
this becomes part of the organism’s body & is stored as molecules (like fat and muscle)
this 10% is all that is available to the next trophic level when that organism is consumed by another organism

12. Lost Energy
one way to visualize the loss of energy from one trophic level to the next level is a pyramid because it has a large base and gets smaller at the top
What group will always be at the base of the pyramid?

13. Energy Pyramid

14. Energy Pyramid Tertiary Consumers Secondary Primary Consumers
Producers

15. Affect of Energy Loss on an Ecosystem
fewer numbers of organisms at the upper trophic levels
# of trophic level is limited – rarely have more than four or five levels
organisms at the top levels are usually feed on by creatures that do not require a lot of energy (decomposers like bacteria & parasitic organisms