1. 4.2 Energy Flow in Ecosystems
I. Trophic Levels
A. Primary source of energy = the sun
B. Producers
1. Use sun’s energy for photosynthesis
2. The basic food source for an ecosystem
C. Consumers
1. Eat other organisms
2. Don’t produce own food

2. D. Decomposers
1. Bacteria & fungi break down remains of dead plants & animals
E. Energy flows from sun to producers to consumers to decomposers
1. Trophic levels
a. each step of energy transfer

3. F. Food Chains
1. 1st level – producers
2. 2nd level – herbivores (eat plants)
3. 3rd level – carnivore (eats others)
4. 4th level – more carnivores (eating other carnivores)
5. Omnivores – animals that eat plants and other animals

4. G. Food Web
1. In most ecosystems energy does not flow in a simple chain
2. Organisms eat more than one kind of food

5. II. Loss of Energy
A. Energy is stored at each link of a food web
B. Only 10% of energy from consumed food become part of the consumer
1. 90% is wasted as heat & energy

6. C. Energy Pyramid
1. a triangular diagram that shows the ecosystem’s loss of energy
2. Each layer represents one trophic level
3. Producers make up the bottom level