1. AGENDA Take out notebooks Bell-ringer: Levels of ORG Food CHAIN notes
Food Chains Practice (with a partner)
Word wall

2. Bell-ringer:
For each numbered picture write which level of organization it represents and WHY. 1 2 3 4

3. 2.1 Section Objectives – page 35
Today’s Objective:
Be able to explain energy transfers among organisms using food chains and food webs.
2.1 Section Objectives – page 35

4. Section 2.2 Summary – pages 46 - 57
The ultimate source of the energy for life is the sun.
Section 2.2 Summary – pages

5. Section 2.2 Summary – pages 46 - 57
The Producers: Autotrophs
An organism that uses light energy (mostly plants) to make food is a producer, or autotroph.
Autotrophs are our link to the energy from the sun. All other organisms depend on autotrophs.
Section 2.2 Summary – pages

6. Autotrophs use the sun’s energy to manufacture food energy in a process called photosynthesis.

7. Section 2.2 Summary – pages 46 - 57
The Consumers: Heterotrophs
An organism that cannot produce it’s own food energy and has to eat/consume other organisms for energy is a heterotroph.
There are different types of heterotrophs.
Section 2.2 Summary – pages

8. Section 2.2 Summary – pages 46 - 57
The Consumers: Heterotrophs
A heterotroph that feeds only on plants (autotrophs) is an herbivore.
Section 2.2 Summary – pages

9. Section 2.2 Summary – pages 46 - 57
The Consumers: Heterotrophs
Some heterotrophs just eat other heterotrophs- these are carnivores.
Section 2.2 Summary – pages

10. Section 2.2 Summary – pages 46 - 57
The Consumers: Heterotrophs
Some heterotrophs eat both heterotrophs and autotrophs They are called omnivores.
Section 2.2 Summary – pages

11. Section 2.2 Summary – pages 46 - 57
The Consumers: Heterotrophs
Scavengers eat animals that have already died.
They don’t actually kill for food, but they only eat dead heterotrophs
Section 2.2 Summary – pages

12. Section 2.2 Summary – pages 46 - 57
The Consumers: Heterotrophs
Some organisms, such as bacteria, fungi, and some worms are decomposers.
Decomposers break down the complex compounds of dead and decaying plants and animals into simpler molecules that can be more easily absorbed/recycled.
Section 2.2 Summary – pages

13. The ultimate source of energy is…….
This energy goes to……
Autotrophs

14. And by eating the heterotrophs that ate autotrophs…..
How do heterotrophs get their energy?
By eating autotrophs…..
And by eating the heterotrophs that ate autotrophs…..

15. Who do you think is getting more energy?

16. Food energy flows through an ecosystem from producers to consumers in a chain…
Matter (like water and carbon) gets recycled.
Energy does not….it changes and is replenished everyday by the sun.

17. Section 2.2 Summary – pages 46 - 57
A food chain is a simple model that scientists use to show how energy moves through an ecosystem.
In a food chain, nutrients and energy move from
autotrophs to
heterotrophs and, eventually, to
decomposers.
Section 2.2 Summary – pages

18. Section 2.2 Summary – pages 46 - 57
The Flow of Matter and Energy
FOOD CHAINS
The arrows in a food chain show the direction of ENERGY FLOW.
berries → mice → black bear
Most food chains consist of only two, three, or four transfers.
Section 2.2 Summary – pages

19. Section 2.2 Summary – pages 46 - 57
The Flow of Matter and Energy
FOOD CHAINS
berries → mice → black bear
1000 kcals
100 kcals
10 kcals
Only about 10% of the energy is transferred at each feeding step…..
This is why a bear would have to eat a lot of mice….
Section 2.2 Summary – pages

20. If only 10% is transferred to the consumer, what happens to the rest of the energy?
LEFT BEHIND AND GIVEN OFF AS HEAT ENERGY

21. Section 2.2 Summary – pages 46 - 57
Each feeding step in a food chain is called a trophic level.
Section 2.2 Summary – pages

22. The first-order heterotroph eats autotrophs.
The first CONSUMER in a food chain is called a primary or first-order heterotroph.
The first-order heterotroph eats autotrophs.

23. Section 2.2 Summary – pages 46 - 57
A second order heterotroph is an organism that feeds on a first order heterotroph.
Section 2.2 Summary – pages

24. A third order heterotroph or tertiary is an organism that feeds on a second order heterotroph.
REMEMBER: a food chain represents only one possible route for the transfer energy through an ecosystem.

25. Food Chain
Food Web
How would you explain the difference between a food chain and a food web?

26. Section 2.2 Summary – pages 46 - 57
Unlike a food chain, a food web, shows ALL the possible feeding relationships at each trophic level in a community.
Section 2.2 Summary – pages

27. In a food web, there can be more than one autotroph, and there can be more than one consumer at each trophic level.
How many first order heterotrophs are there in this food web?
Which organism is both a first and second order heterotroph?

28. Section 2.2 Summary – pages 46 - 57
An ecological pyramid is another way to show a food chain.
The autotroph is always at the bottom of the pyramid
As you go up the pyramid, you go higher in the trophic levels
Fox (1)
Birds (25)
Grasshoppers (250)
This pyramid is a pyramid of NUMBERS.
Grasses (3000)
Section 2.2 Summary – pages

30. Section 2.2 Summary – pages 46 - 57
This pyramid shows ENERGY LOSS.
Pyramid of Energy
Heat
0.1% Consumers
Heat
1% Consumers
10% Consumers
Heat
100% Producers
Heat
Parasites, scavengers, and decomposers feed at each level.
Section 2.2 Summary – pages