<p>Name: ______Block: ______Date: ______</p><p>FOOD WEBS</p><p>Objective: In this activity, you will learn about relationships in an ecosystem. You will reinforce your knowledge about trophic levels and energy transfer, and learn about biomagnification.</p><p>Directions: Part I 1. Begin by cutting out each of the organisms that belong to the grassland community. 2. Separate the organisms into groups: the sun, producers, herbivores, carnivores, omnivores, decomposers. Shade each group a different color lightly. 3. Look at each organism- each card is labeled with the name of the organism, its role in the community, and the organisms it eats if it is a heterotroph. Starting with the sun, construct a food chain. Be sure to pay attention to the foods that each organism eats- don’t just make it up! Get your food chain checked by the teacher. Part II 4. Using all the cards, construct a food web for the grassland community. Remember that each organism must have at least two food sources. Do not glue the cards down until your food web has been checked by the teacher. Draw the arrows to show the flow of energy in pencil. 5. If your food web is correct, glue down the organisms and darken in the energy arrows with a marker. Remember that the arrow should go from the food source to the organism that is eating it, not the other way around. Part III 6. Ask the teacher to spray a plant with pesticides. 7. Using a black colored pencil, lightly shade in all the organisms that will be affected by that pesticide. It is important to understand that not all organisms will die when they eat the pesticides, but the pesticides will build up in the organisms as you move from trophic level to trophic level. 8. Clean up and return all materials before you leave the classroom. Wipe off your desk if there is any glue on it. Answer all questions in complete sentences on a clean sheet of lined paper. Questions: answer the following in complete sentences… 1. What are some of the abiotic factors in a grassland community? 2. Define the following terms: producer, herbivore, carnivore, omnivore, decomposer. 3. What is the difference between autotrophs and heterotrophs? 4. Why can food chains only have only have a maximum of four or five trophic levels? 5. What percent of energy is passed from one trophic level to the next? What happens to the energy that is not passed on? 6. What is the difference between cycle and flow? What is something that is cycled in your food web and what is something that flows in your food web? 7. What is the difference between a food chain and a food web? 8. Why is it important that a heterotroph have more than one food source? What is the risk of an organism only having one food source? Give an example. 9. Why do the arrows in a food web go in the direction that they do? 10.Why are decomposers an essential part of every ecosystem? (In other words- what would happen if they were not there?) 11.What is biomagnification? What is an example in a marine ecosystem? 12.Look at your food web. What would happen if one of the producers was removed/died off? 13.What would happen to the producers if you removed one of the herbivores? What would happen to the carnivores that rely on that herbivore? 14.Why are the 2nd level carnivores more likely to be affected by the insecticide than 1st level carnivores?</p>