Energy Flow Through Ecosystems

1. Energy Flow Through Ecosystems Activity 7

2. Activity 7 Bellwork Complete the following statements: • Phytoplankton are ______________, which means they make their own food. • Zooplankton are ______________, which means they obtain energy by eating other organisms. • An herbivore eats _______________. • A carnivore eats _____________. • An ______________ eats a variety of kinds of food.

3. Activity 7 Challenge: • How can we use food webs to predict the short- and long-term effects of particular events on an ecosystem?

4. Activity 7 Key Terms • Decomposers- organisms that consume dead organisms and keep nutrients flowing through the ecosystem • Food Web- a diagram showing the interrelationships between organisms and how energy flows through an ecosystem

5. Food chain = just one pathFood Web = everything is connected

6. Trophic Levels

8. 10% Law

9. 10% Law • During the transfer of organic food from one trophic level to the next, only about ten percent of the available energy is stored and available for the next level. The remaining is lost, usually as heat. • Plants utilize sun energy for primary production and can store only 10% of the energy available from the sun. That 10% is available to herbivores, • When the plants are consumed by animal, about 10% of the energy in the food is fixed into animal flesh which is available for next trophic level (carnivores). • When a carnivore consumes that animal, only about 10% of energy is fixed in its flesh for the higher level.

11. 10% Law • So at each transfer 80 - 90% of potential energy is dissipated as heat (second law of thermodynamics) where only 10 - 20% of energy is available to the next trophic level.

12. For Today: Workbook pages 139, 140, 142 15 points at the beginning of class tomorrow!