The document discusses the roles and relationships between organisms within an ecosystem. It explains that an organism's role depends on how it obtains energy and how it interacts with other organisms. Organisms can be producers, consumers, or decomposers. Producers like plants make their own food, consumers eat other organisms and obtain energy that way, and decomposers break down dead organisms. Food chains and webs show how energy flows between organisms as they consume each other. Ecosystems rely on a balance of these relationships, and a change in one organism can impact the entire food web.

1. Middle School Science
Mrs. Figoten

2. ALL LIVING THINGS
NEED ENERGY
In an ecosystem, an
organism’s role depends on:
How it obtains energy &
How it interacts with the other living things
in the ecosystem
Organism’s energy role is:
Producer
Consumer
Decomposer

4. Introducing
PRODUCERS
It all begins with plants that
make their own food…..

6. CONSUMERS CAN BE…
Herbivores
eat plants
Carnivores
eat animals
Omnivores
eat plants and animals
Scavengers
eat dead animals

7. DECOMPOSERS ARE
NATURE’S RECYCLERS
BACTERIA
FUNGI
SOME SOIL ORGANISMS

8. “3rd level
consumer” consumer
“2nd level
consumer”
“1st level
consumer”
Food chains show the flow of energy through consumer levels

12. known

13. CONIFEROUS FOREST
FOOD WEB

16. ECOSYSTEMS DEPEND
ON THE BALANCE OF
THEIR FOOD WEBS
The loss of one organism may tip the
delicate balance of survival for many
other organisms within that food web

17. POPULATION SURVIVAL
 Limiting Factors
Prevent population from increasing
Can happen if too many predators or not
enough food -- changes in food web
 Carrying Capacity
Largest population that
environment can support
Can happen from changes in food web
Population graph goes up & then flattens

18. “Carrying Capacity”
of Ecosystem
(Most of one species ecosystem can hold)
Rabbit Growth Curve
30
25
Population Size
20
15 Population
10
5
0
0 2 4 6 8 10 12
Year
Population Graph goes up as species multiplies, then flattens
when there is no more food to continue reproducing.
Population of species can no longer grow.

19. Series of
Predictable Changes
That Happen in a
Community Over Time

20. Changes Over
Time Where
No Ecosystem
Existed Before
New Growth
Begins with
Lichen & Mosses

21. Mature Bushes & Grasses & Lichen &
Hardwood Small Trees Small Plants Mosses
Trees after after 20- after 5-15 first few
150+ years 100 years years years

22. Changes Over
Time After a
Disturbance
Such as a
Forest Fire
in an
Ecosystem

23. Mature Hardwood
Trees after
150+ years