1. Energy Flow

2. Food Chains and Food Webs Block 1
Energy Flow within Ecosystems Block 2
Biogeochemical Cycles Block 3

3. Food Chains and Food Webs BLOCK 1

4. Essential question
The transfer of energy in an ecosystem is referred to as “energy flow”, and not “energy cycling”. Explain.

5. “troph” – to nourish Autotroph are producers that make their own food.
Heterotrophs are consumers that must eat food to obtain energy.

6. “Vore” - to eat Herbivore - a plant eater
Carnivore - an organism that obtains nutrients from the blood or flesh of an animal
Omnivore - an organism which eats both plant and animal matter

7. Decomposer and Detritivore
Detritivore - a consumer that obtains its nutrients from detritus (dead organic matter)
Ex: Scavengers, worms, vultures
Decomposer – break down and absorb nutrients from dead organisms.
Also release nutrients
Ex: Bacteria, fungi (mushrooms)

8. Food Chain
A food chain is the series of organisms showing feeding relationships. A food chain usually begins with a green plant (producer) which is eaten by an animal (consumer). The arrow means 'is eaten by', and shows the flow of energy along the food chain.
Producer -> Consumer 1 -> Consumer 2 -> Consumer 3 ->
Herbivore Carnivore Carnivore

9. A network of interrelated food chains in a given area
Food Web
A network of interrelated food chains in a given area

10. Producers & Consumers Producer – Primary Consumer –
Usually plants that produce their own food by photosynthesis.
Primary Consumer –
Herbivores that eat plants.
Secondary Consumer -
Carnivores that eat herbivores.
Tertiary Consumer -
Carnivores which eat other carnivores.
Apex Predator which have no predators are at the top of the food chain.

11. Consumers Secondary consumers (eat herbivores)
Tertiary consumers (carnivores that eat other carnivores)
Primary consumers (Herbivores)
Examples
Giraffe
Catapillar
Zooplankton
Omnivores- (herbivore+carnivore)
Figure 3.8: The giraffe (left) feeding on the leaves of a tree is an herbivore. The lions (right) are carnivores feeding on the dead body of a giraffe that they have killed.
Fig. 3-8a, p. 60

12. Trophic Level
A trophic level is each level in a food chain.

13. Trophic Levels 1st trophic level = producers
2nd trophic level = primary consumer
3rd trophic level = secondary consumer
4th trophic level = tertiary consumer

14. Check for understanding: Let’s Guess The Order of the Trophic levels together…

15. Three Types of Pyramids
Number Pyramid
Energy Pyramid
Biomass Pyramid

16. 10% Rule
When one animal feeds off another, only about 10% of the available energy is transferred.
There is a loss of energy in the form of heat in the process.
Additional loss of energy occurs during respiration and movement of the organisms before they are eaten.
More and more energy is lost as one moves up through trophic levels.

17. Usable energy available at each trophic level
(in kilocalories)
Heat
Tertiary consumers (human) 10
Heat
Secondary consumers (perch)
100
Heat
Decomposers
Heat
Primary consumers (zooplankton)
1,000
Figure 3.14: This model is a generalized pyramid of energy flow that shows the decrease in usable chemical energy available at each succeeding trophic level in a food chain or web. The model assumes that with each transfer from one trophic level to another, there is a 90% loss in usable energy to the environment in the form of low-quality heat. (Calories and joules are used to measure energy. 1 kilocalorie = 1,000 calories = 4,184 joules.) Question: Why is a vegetarian diet more energy efficient than a meat-based diet?
Heat
10,000
Producers (phytoplankton)
Fig. 3-14, p. 65

18. ENERGY FLOWS and is Transformed
Law of Conservation of Energy:
Energy can NOT be created nor destroyed
Energy CAN be degraded
Always goes in the direction of
HIGH quality energy ----> LOW quality energy

19. Do Now: Construct a Food Web