1. Energy in Ecosystems

2. Trophic Levels Each link of the food chain is known as a trophic level
Tropic level refers to the feeding level of an organism
Troph is Greek for food

5. Energy in Ecosystems
Energy is lost at each tropic level through life process:
respiration, digestion, movement, reproduction
As you move up the food chain less energy available for top consumers

6. Energy Pyramids
10% Rule – i.e. only 10% of energy is available for the next trophic level

7. Demo Questions…..
1. If the food chain had continue to the next level, what percentage of energy would the fourth- level consumer have received from the third-level consumer?
2. How much water would you have transferred into the fourth-level consumer’s cup?
3. Judging from this activity, why do you think most food chains never go higher than second- or third- level consumers?

8. QUICK REVIEW
If 100% of the energy is available at the first trophic level, what percentages of the energy are available at the second and third trophic levels? 1%
10%
100%

9. Ecological Pyramids The base of food chains is bigger then the top
This is called an ecological pyramid
A level of the energy pyramid is called a TROPHIC LEVEL

10. ENERGY PATHS 3 ways to illustrate energy flow
1. Food Chain: Single path
3 ways to illustrate energy flow
3. Food Pyramid
2. Food Web: many paths

11. Questions….
1. Why is it necessary for the number of prey to be greater than the number of predators in order for an ecosystem to be balanced?
2. Complete the chart: A plant produces 5000KJ of energy.
3. Draw a pyramid of energy to represent the food chain above.
4. Make a pyramid of energy with rabbits, snakes, wolves and KJ of grass
Energy entering Organism
Energy used by living Organism
Energy Available for next tropic level
Plant- 5000KJ
Deer
Wolf