Making a Food Web. Procedure

Transcription

1 Name Class Date One organism consumes another for energy and raw materials. A food chain shows the sequence in which energy passes from one organism to another as it flows through a community. In this lab, you will draw food chains that might be found in a woodland community and show how the food chains are connected to form a food web. OBJECTIVES Depict three food chains within a woodland community. Combine the food chains into a food web. MATERIALS paper pen or pencil Procedure 1. Closely observe Figure 1, which shows a portion of a woodland community. List all the organisms that you see. FIGURE 1 A WOODLAND COMMUNITY Holt Program Biology Title 49 Chapter Ecosystems Title

2 Name Class Date continued 2. Add to your list other organisms that might be present in this community but are not shown. 3. On a separate sheet of paper, write the name of one organism from your list that is capable of photosynthesis. 4. Draw a short arrow leading from this organism to the name of a second organism that might eat it. These are the first two links of a food chain. 5. Extend your chain to three links by adding an arrow and a third organism that might consume the second. 6. Extend your food chain to four links. 7. Make two more food chains consisting of four links each. 8. Construct a food web by drawing arrows to show how organisms in the three food chains are linked to one another. Make as many connections as possible. Analysis and Conclusions 1. Analyzing Data How are food chains and food webs alike? How are they different? 2. Evaluating Models How is a diagram of a food web more helpful than a written description of the same information? 3. Drawing Conclusions If all the green plants were removed from the woodland community, how might the flow of energy be affected? Explain your answer. 4. Drawing Conclusions If the top-level consumers were eliminated from a food web, would the populations in the levels below them increase without bounds? Why or why not? Holt Program Biology Title 50 Chapter Ecosystems Title

3 Teacher Notes TIME REQUIRED 20 minutes SKILLS ACQUIRED Communicating Constructing models Inferring Organizing and analyzing data RATINGS Teacher Prep 1 Student Setup 1 Concept Level 2 Cleanup 1 Easy Hard THE SCIENTIFIC METHOD Make Observations Step 1 of the Procedure requires students to make observations. Analyze the Results Analysis and Conclusions question 1 asks students to analyze their results. Draw Conclusions Analysis and Conclusions questions 3 and 4 ask students to draw conclusions based on their results. TIPS AND TRICKS This lab works best in groups of two or individually. No outside preparation is required for this lab, but showing slides, transparencies, or photographs of organisms common to a woodland habitat can be helpful. To enhance the lab, you may wish to provide nature magazines and similar materials from which students can cut out pictures of the organisms in their food chains. You may want to substitute a local community for the woodland community shown or use a community that is more familiar to your students. Discuss the types of organisms that might inhabit the community. After students make their food web, have them follow the individual food chains within the web and determine the total number of chains. Holt Program Biology Title 66 Chapter Ecosystems Title

4 Name Class Date One organism consumes another for energy and raw materials. A food chain shows the sequence in which energy passes from one organism to another as it flows through a community. In this lab, you will draw food chains that might be found in a woodland community and show how the food chains are connected to form a food web. OBJECTIVES Depict three food chains within a woodland community. Combine the food chains into a food web. MATERIALS paper pen or pencil Procedure 1. Closely observe Figure 1, which shows a portion of a woodland community. List all the organisms that you see. Students should list all the organisms visible in the illustration. FIGURE 1 A WOODLAND COMMUNITY Holt Program Biology Title 67 Chapter Ecosystems Title

5 Name Class Date continued 2. Add to your list other organisms that might be present in this community but are not shown. Students might list microorganisms and other fungi, plants, invertebrates, and vertebrates. 3. On a separate sheet of paper, write the name of one organism from your list that is capable of photosynthesis. 4. Draw a short arrow leading from this organism to the name of a second organism that might eat it. These are the first two links of a food chain. 5. Extend your chain to three links by adding an arrow and a third organism that might consume the second. 6. Extend your food chain to four links. 7. Make two more food chains consisting of four links each. 8. Construct a food web by drawing arrows to show how organisms in the three food chains are linked to one another. Make as many connections as possible. Analysis and Conclusions 1. Analyzing Data How are food chains and food webs alike? How are they different? Both food chains and food webs show the flow of energy from organism to organism within a community. A food web is more complex than a food chain because it shows how the individual food chains within the community are linked to one another. 2. Evaluating Models How is a diagram of a food web more helpful than a written description of the same information? Because a food web diagram is a graphical representation, it can be used to see more easily how energy flows through a particular community. 3. Drawing Conclusions If all the green plants were removed from the woodland community, how might the flow of energy be affected? Explain your answer. The flow of energy would stop because green plants, which use the sun s energy to make food, are the base of the community s available energy. 4. Drawing Conclusions If the top-level consumers were eliminated from a food web, would the populations in the levels below them increase without bounds? Why or why not? No, population size is affected by many factors, including predation, weather, available food, available space, disease, and other biotic and abiotic factors. Holt Program Biology Title 68 Chapter Ecosystems Title