1. Part 1: Food Chains, Food Webs, and the Transfer of Energy
Chapter 5: Energy
Part 1: Food Chains, Food Webs, and the Transfer of Energy

2. Autotrophs
An organism capable of making its own organic substances from inorganic compounds
Also called Producers
Without autotrophs, there would be no life on this planet

3. There are 2 types of autotrophs: The first type is the…
Photoautotrophs
A group of organisms that can change light energy into chemical energy (glucose) – Photosynthesis!
Example: green plants, algae, cyanobacteria

4. Photoautotrophs

5. The second type of autotrophs are the …
Chemoautotrophs
Autotrophs that get their energy from inorganic substances, such as sulfur
Live deep down in the ocean where there is no sunlight
Ex. Some bacteria

6. Heterotrophs Organisms that do not make their own food (needs to eat)
Another term for Heterotroph is Consumer because they consume other organisms in order to live. Heterotrophs give off carbon dioxide, which is required for green plants in photosynthesis
Ex. Rabbits, Deer, Mushrooms

7. Heterotrophs

8. Heterotrophs: Herbivores
1st Order Consumer = Herbivore
Herbivores – eat ONLY plants
Ex. – Cows, Elephants, Giraffes

9. Heterotrophs 2nd Order Consumer They are carnivores (eat meat)
Eats first order consumers
Ex. – Lions, Tigers, Sharks

10. Heterotrophs 3rd Order Consumer eats 2nd order consumers
4th Order Consumer
eats 3rd order consumers

11. Heterotrophs: Omnivores
Omnivores – eat BOTH plants and animals
Ex. – Bears and Humans

12. Heterotrophs: Scavengers
Scavengers – feed on the tissue of dead organisms (both plants and animals)
Ex. – Vultures, Crows, and Shrimp

13. Heterotrophs: Decomposers
Decomposers – absorb any dead material and break it down into simple nutrients or fertilizers
Ex. – Bacteria and Fungi (such as mushrooms

14. Ok, now that we know the words…
Let’s put them together to show the flow of energy through the ecosystem …
Food web video

15. Transfer of Energy
When a zebra eats the grass, it does not obtain all of the energy the grass has (much of it is not eaten)
When a lion eats a zebra, it does not get all of the energy from the zebra (much of it is lost as heat)

16. Transfer of Energy
No organism EVER receives all of the energy from the organism they just ate
Only 10% of the energy from one trophic level is transferred to the next – this is called the 10% law
Trophic level = energy level (each step of the food chain is a trophic level)

17. Transfer of Energy: The 10% Rule
Who eats who in the food chain
Steps along which materials & energy pass
heat
activity

18. The 10% Rule

19. Food Chains
The energy flow from one trophic level to the other is known as a food chain
It involves one organism at each trophic level

20. Food Chain
Identify:
Source of the energy
Producer
Herbivore
Carnivore

21. Food Chain Identify: Source of the energy Producer Herbivore
Carnivores
1st order consumer
2nd order consumer
3rd order consumer

22. Food Web Food Web – all of the feeding relationships in an ecosystem
Food webs are more complex and involve lots of organisms

23. Food Web

24. Food Web Notice the direction the arrow points 
The arrow points in the direction of the energy transfer, NOT “what ate what”

25. Marine Food Web

26. Ecological Pyramids 4th order consumers 3rd order consumers
2nd order consumers
1st order consumers (herbivores)
Producers

27. Ecological Pyramid
An ecological pyramid shows the relationship between consumers and producers at different trophic levels in an ecosystem
Shows the relative amounts of energy or matter contained at each trophic level
The Pyramid shows which level has the most energy and the highest number of organisms

28. Ecological Pyramids Illustrates: Food Chain of numbers of biomass
of energy

29. Pyramid of Numbers

30. Biomass
The total mass of the organic matter at each trophic level is called biomass
Biomass is just another term for potential energy – energy that is to be eaten and used.
The transfer of energy from one level to another is very inefficient (10% Law)

31. Pyramid of Biomass

32. Energy Pyramid

33. Which level has the most energy?
Which level has the most organisms?
Which level has the least organisms?
Which level has the least energy?