Background Energy Flow The following page illustrates a sample diagram of a food chain. Notice the dark black arrows and the direction in which they are pointing. The arrows indicate the flow of energy FROM one organism TO another in a food chain. A food chain is the path of energy from one organism to another in an ecosystem. Energy is required by organisms to survive, and comes either from the Sun (for plants) or other organisms (for animals). A producer transforms the energy of the Sun to make food. A consumer eats producers or other consumers to obtain energy. A decomposer breaks down plant and animal remains and waste into molecules that producers reuse to make energy available for consumption. Food chains show how energy transforms as it flows from the Sun to producers to primary consumers (herbivores), to secondary consumers (carnivores that eat herbivores) to tertiary consumers (carnivores that eat carnivores.) Review the food chain diagram on the following page. 1
Background, continued Continue to the next page. 2
Background, continued Food webs show the complex relationships of energy flow in an ecosystem that contains a variety of producers and consumers. PRODUCER Uses radiant energy from the Sun, carbon dioxide from the air, and water from the soil to produce its own food. PRIMARY CONSUMER OR HERBIVORE Eats plants. Has the ability to digest the plants it eats and releases the energy stored in the plant cells for its own use. SECONDARY CONSUMER OR CARNIVORE Eats the animals that eat the plants. DECOMPOSERS Eats the dead bodies of both plants and animals. Gets its energy from the cells of plants and animals. Turns the remains of the plants and animals into nutrients, which are released into the soil. The nutrients (plus radiant energy and water) cause plants to grow. Complete the Background questions in your Student Journal. 3
Part I: Diagram the Energy Flow Through a Food Chain 1. Choose an ecosystem with your partner and gather the organism cards from your teacher. 2. Choose five organism cards showing the progression through a food chain from producers to consumers. 3. Make five construction paper rings. 4. Use a loop of masking tape to attach each organism card to a construction paper ring. 5. Make four more construction paper strips. Use the strips to connect the construction paper rings in a chain. 6. Draw an arrow on the linking strip from the first picture to the next. Repeat for each connecting link. Tape the arrow link to the picture rings to keep the arrow in place. 7. Draw a diagram in your Student Journal of the model food chain you created. Use arrows to show the path of food energy from one organism to another. Arrows show: Energy Flow Part II: Comparison Table 1. Gather food chain information for the other three ecosystems from the other groups in the class. 2. Record all information on the table in your Student Journal, including your own food chain. Use arrows to show the path of food energy from one organism to another. Complete the Part I questions in your Student Journal before continuing with Part II. 4
Part III: Diagram the Energy Flow Through a Food Web Follow the instructions to diagram the energy flow through a food web. 1. Use the same ecosystem organism cards from Part I. 2. Get dry erase markers, a laminated sheet of poster board and a roll of masking tape from your teacher. 3. Arrange all of the organism cards into a food web on the poster board with your partner. Use loops of masking tape on the backs of the cards to secure the cards to the poster board. 4. Use the dry erase markers to draw lines between the cards to represent the flow of energy. Use one color to represent the energy flow from each organism. Create a legend in your Student Journal to provide details. For example: a green line shows energy flowing from plants. 5. Draw a diagram of the model food web you created in your Student Journal. Use arrows to indicate the energy flow from one organism to another. 6. Once you have completed your diagram in your Student Journal, remove the organism cards from the poster board and from your food chain model. Remove the tape from the back of the cards. Use a damp paper towel to wipe off the dry erase marks on the poster board. Place the used tape and paper towel in a trash bin. Return the organism cards and poster board to your teacher. Draw the diagram for Part III in your Student Journal and then continue with Part IV. 5
Part IV: Diagram the Energy Flow through an Energy Pyramid Energy pyramids show how the amount of energy decreases as it flows from producers at the bottom of the food chain to tertiary consumers at the top of the food chain. As energy flows up the pyramid, some energy transforms into heat. Energy passes up the pyramid, but the total energy amount is not transferred from one level to the next. Less energy is available at the top of the pyramid. On average, about 10 percent of the energy available within one level is transferred to the next level. Continue to the next page. 6
Part IV: Diagram the Energy Flow through an Energy Pyramid, continued Complete the Energy Pyramid using the appropriate organisms from your ecosystem s food web in your Student Journal. Ecosystem First Level Complete Part IV and the Reflection and Conclusion questions in your Student Journal. 7