1. Losing Energy and the 10% Rule

2. Energy Units
energy is typically measured in joules (J) or calories (cal)

3. Energy Units calorie vs. Calorie vs. Kilocalorie
the amount of energy necessary to raise 1gram of water 1 ° C
Calorie
A food Calorie = kilocalorie
kilocalorie
1,000 calories

4. An Important Reminder…
Energy flows in one direction through an ecosystem, from the sun or inorganic compounds to producers (organisms that can make their own food) through various levels to consumers (organisms that rely on other organisms for food). Your body gets the energy and materials it needs for growth and repair from the foods you eat.

5. Think, Pair, Share Warm-up
Spend 30 seconds in silence thinking about your response to yourself
Pair
Discuss with your partner (or table groups) what you thought about during the 30 seconds
Share
Share your table’s discussion with the whole class.
Describe how the number of species in lower trophic levels compares with the number of species in higher trophic levels. Explain a reason for why this occurs.

6. Energy Flow

7. Fig. 47-5, p.846

8. Energy Losses energy transfers are never 100 percent efficient
some energy is lost at each step as heat
limits the number of trophic levels in an ecosystem because there is a limited amount of energy inputted by the sun

9. 10 % Rule
the maximum amount of energy that passes from one trophic level to the next is 10 %

10. 10 % Rule

11. 10 % Rule
Why do you think only 10% of the total energy from 1 trophic level is passed to the next?

12. Reasons for Decrease in Energy
the remaining 90 % of the energy is not available to the next trophic level
energy is “used up” for daily life activities
not all organisms that die are eaten by animals in the next trophic level
not all parts of an organism are eaten and digested for energy
some energy is lost as heat created during cellular respiration

14. 10 % Rule Predictions
can be used to predict the flow of energy, population numbers, and amounts of biomass
biomass – amount of biological matter

15. Ecological Pyramid
diagram that displays the 10% Rule and loss of energy, population numbers, or amounts of biomass

16. Ecological Pyramids - Energy

17. Ecological Pyramids - Biomass

18. Ecological Pyramids - Population

19. 10% Rule Patterns in Ecological Pyramids
90% lost as heat

20. 10% Rule Patterns in Ecological Pyramids
90% lost as heat

21. 10% Rule Patterns in Ecological Pyramids
90% lost as heat

22. How much energy is at each level?
1. If the producer level absorbed 10,000 Calories, how much energy was transferred to the other levels?
10,000 Cal
? Cal

23. How much energy is at each level?
1. If the producer level absorbed 10,000 Calories, how much energy was transferred to the other levels?
10,000 Cal
1,000 Cal
? Cal

24. How much energy is at each level?
1. If the producer level absorbed 10,000 Calories, how much energy was transferred to the other levels?
10,000 Cal
1,000 Cal
100 Cal
? Cal

25. How much energy is at each level?
1. If the producer level absorbed 10,000 Calories, how much energy was transferred to the other levels?
10,000 Cal
1,000 Cal
100 Cal
10 Cal

26. How much energy is lost at each level?
90 Cal as heat
10,000 Cal
1,000 Cal
100 Cal
10 Cal
900 Cal as heat
9,000 Cal as heat

27. Using the 10% Rule with Ecological Pyramids
2. To the right is a diagram of a prairie food web. A pesticide was placed on the prairie that began to kill grasshoppers. Will the pesticide application affect the snake? How or why?

28. Using the 10% Rule with Ecological Pyramids
3. Draw an Ecological Pyramid to show how energy flows through the prairie food web. Include three levels of consumers (and one level of producers) in your pyramid. In the “Organism” column, write one species per level. In the “Type of Energy Use” column, label each chose species based on how they get their energy (Autotroph, Herbivore, Carnivore, Omnivore, Detritovore, or Decomposer). Use 1,000 Calories at the producers’ level to start your pyramid. Finally, use the 10% Rule to complete the Energy Ecological Pyramid.