Ecosystems and Energy Flow

Transcription

1 Ecosystems and Energy Flow Biology HS/ Unit: 02 Lesson: 02 Suggested Duration: 5 days Lesson Synopsis: In this lesson, students explore how organisms cycle energy and matter between one another and the environment. TEKS: B.11 concepts. The student knows that biological systems work to achieve and maintain balance. The student is expected to: B.11C Summarize the role of microorganisms in both maintaining and disrupting the health of both organisms and ecosystems. Supporting Standard B.12 concepts. The student knows that interdependence and interactions occur within an environmental system. The student is expected to: B.12A B.12C B.12D B.12E Interpret relationships, including predation, parasitism, commensalism, mutualism, and competition among organisms. Readiness Standard Analyze the flow of matter and energy through trophic levels using various models, including food chains, food webs, and ecological pyramids. Readiness Standard Recognize that long-term survival of species is dependent on changing resource bases that are limited. Supporting Standard Describe the flow of matter through the carbon and nitrogen cycles and explain the consequences of disrupting these cycles. Supporting Standard Scientific Process TEKS: B.2 Scientific processes. The student uses scientific methods during field and laboratory investigations. The student is expected to: B.2G B.2H Analyze, evaluate, and make inferences and predict trends from data. Communicate valid conclusions supported by the data through methods such as lab reports, labeled drawings, graphic organizers, journals, summaries, oral reports, and technology-based reports. GETTING READY FOR INSTRUCTION Performance Indicator(s): For two ecosystems, analyze and compare the flow of matter and/or energy using models such as various food chains, food webs, ecological pyramids, and the carbon and nitrogen cycles. Given an amount of energy for a particular trophic level, calculate the amount of energy in subsequent trophic levels using the 10% rule. (B.2G, B.2H; B.12A, B.12C, B.12D, B.12E) 1C; 4D; 5B Key Understandings and Guiding Questions: Matter and energy in ecosystems pass through food webs. At each trophic level in a food web, energy is used and lost to the environment. What happens to energy as it is passed from producers to consumers? Matter is recycled through systems and various cycles, such as the carbon and nitrogen cycles. How do chemicals cycle through ecosystems? Vocabulary of Instruction: food web ecological pyramid producer consumer primary consumer secondary consumer tertiary consumer herbivore carnivore omnivore decomposer detritivore (detrivore) trophic level See section for materials. 2012, TESCCC 04/11/13 page 1 of 7

2 Teacher Resource: Organism Cards (see Adv. Prep., 1 set per group) Handout: Food Chain Race (1 per student) Handout: Is It True? Ecosystems and Energy Flow (1 per student) Teacher Resource: Is It True? Ecosystems and Energy Flow KEY Handout: Ecological Pyramid Investigation (1 per student) Teacher Resource: Ecological Pyramid Investigation KEY Teacher Resource: Ecological Pyramid Investigation Graphics (see Adv. Prep., 1 set per group) Handout: Nitrogen and Carbon Cycles Web Quest (1 per student) Teacher Resource: Nitrogen and Carbon Cycles Web Quest KEY Handout: Ecosystems and Energy Flow Project PI (1 per student) Teacher Resource: Performance Indicator Instructions KEY Advance Preparation: 1. Prior to Day 1: Obtain at least one graphic of a food web to display for students during the Engage portion of the lesson. Print the Teacher Resource: Organism Cards, and copy on cardstock front-back at 100%, so each card has a picture on the front and its name on the back. You will need to copy, cut, laminate, and bag sets for groups of 2 3 students. Note: You may wish to print only pages 1 and 2, as page 3 contains only image citations. 2. Prior to Days 1, 4, and 5, arrange for student computer access or secure research materials from locally adopted textbooks or other district-approved resources. 3. Prior to Day 2, prepare the materials for the Ecological Pyramid lab activity. Print one copy of the Teacher Resource: Ecological Pyramid Investigation Graphics for each lab group onto cardstock. It is preferable to print the graphics in color. You will need to print, cut, laminate, and sort the graphics into the four groups as identified on the teacher resource. Place each group into its own resealable, plastic bag with correct label (producers, primary consumers, secondary consumers, and tertiary consumers). 4. Prior to Day 3, locate and preview appropriate websites for students to use during the Nitrogen and Carbon Cycles Web Quest. 5. Prepare attachments as necessary. Background Information: Students in Grade 7 have previously studied energy flow through ecosystems through food webs and energy pyramids. In the previous lesson, students learned about relationships between different organisms in an ecosystem, and organisms dependence on and competition for biotic and abiotic factors. In this lesson, students will analyze the flow of matter and energy through trophic levels and cycles, and recognize the effect of changing resources on survival. STAAR Note: A number of student expectations are addressed in this lesson. B.11C and B.12DE are Supporting Standards, and Readiness Standards B.12AC will be tested on the STAAR Biology Assessment. GETTING READY FOR INSTRUCTION SUPPLEMENTAL PLANNING DOCUMENT Instructors are encouraged to supplement and substitute resources, materials, and activities to differentiate instruction to address the needs of learners. The Exemplar Lessons are one approach to teaching and reaching the Performance Indicators and Specificity in the Instructional Focus Document for this unit. Instructors are encouraged to create original lessons using the Content Creator in the Tools Tab located at the top of the page. All originally authored lessons can be saved in the My CSCOPE Tab within the My Content area. INSTRUCTIONAL PROCEDURES Instructional Procedures ENGAGE Ecosystems and Energy Flow NOTE: 1 Day = 50 minutes Suggested Day , TESCCC 02/09/12 page 2 of 7

3 1. In their science notebooks, instruct students to write down what they ate for breakfast (or dinner last night if they did not eat breakfast) and where the food was originally produced. Give students the following example: If a student ate a bagel with a glass of orange juice, then the bagel came from wheat/grains in a field, and the orange juice came from an orange tree in a field. 2. Ask for a few student volunteers to share the food items they wrote down. Facilitate a discussion: Why do we eat food? (To obtain energy) Does the food we eat also need energy?(yes) Where does the food we eat get its energy? Answers may vary slightly, but students should conclude that ultimately all energy on the planet comes from the Sun. 3. Distribute two index cards to each student. Instruct students to work with a partner to draw the components of a meal. They need to determine the flow in which the energy of the meal travels (from the Sun to the student). (Example: turkey sandwich bread: Sun grains student; turkey: Sun grains turkey student). 4. As students are creating their meal/energy flow cards, circulate and provide assistance if needed. 5. When completed, ask for volunteers to share their meal/energy flow cards with the class. 6. Write a student s meal/energy flow on the board. Continue the discussion: What is this representation of energy flow called? (A food chain) What is the food chain showing? (The flow/transfer of energy from one organism to another) 7. Display a graphic of a food web (see Advance Preparation). What does this graphic represent? (A food web) How is a food web different than a food chain? (A food web is many interconnecting food chains, representing the fact that most organisms eat more than one thing.) Why does the arrow point away from the organism that is being eaten? (Cite an example on your specific food web.) (Because the arrow shows the transfer of energy. The animal that is being eaten transfers some energy to the animal that eats it.) index cards (4 x6, 2 per student) food web graphic (for projection, see Advance Preparation) glue or tape (per pair of students) Instructional Notes: Students have previously studied food webs and energy pyramids in middle school. It is likely that students will have good basic background knowledge of food chains, and they should be able to independently complete this activity. Misconception: Students may think the arrows in a food web point to what an organism eats rather than representing the flow of energy. (This causes students to place all arrows in a food web in the wrong direction.) Notebooks: Students reflect on the origins of food products and attach food chains to notebooks. 8. Instruct students to affix the index cards to their science notebooks. EXPLORE Ecosystems and Energy Flow 1. Divide the class into groups of 2 3 students. Suggested Day 1 (continued) 2. Distribute to each group of students a stack of organism cards from the Teacher Resource: Organism Cards and the Handout: Food Chain Race to each student. 3. Instruct students to create as many realistic food chains as possible using the organism cards. They must record each food chain on the handout. 4. Inform students they will have five minutes to complete this task. When ready to begin, say, GO! and start the timer. stopwatch or other timing device (1 per teacher) paper (butcher, large, 1 sheet per class) tape (per class) markers (per class) 2008, TESCCC 02/09/12 page 3 of 7

4 5. Monitor students during this activity to ensure they are creating realistic food chains. 6. When finished, ask each group to share one of their food chains with the class. 7. Instruct students to use as many organism cards as possible to create a food web. Students should record this food web on their Handout: Food Chain Race. 8. Create a class food web using a large piece of butcher paper and markers. Ask each group to contribute links in the food web from the food web their group created. Teacher Resource: Organism Cards (1 set per group, see Advance Preparation) Handout: Food Chain Race (1 per student) Instructional Note: You may wish to offer a small prize to the winning group during the Food Chain Race activity. 9. Try to make as complete a food web as possible; this food web will be used during the Explain portion of the lesson. EXPLAIN Ecosystems and Energy Flow Suggested Days 1 (continued) and 2 1. Distribute to students the Handout: Is it True? Ecosystems and Energy Flow. Instruct students to read each of the statements and to determine if the statement is true or false. 2. Students should use only their background knowledge at this point. Emphasize that it is okay to be wrong; students just need to try their best. 3. After students have marked each statement as true or false, instruct them to use available resources to determine if they were correct (see Advance Preparation). 4. For any false statement, students should rewrite the statement to make it a true statement. If students are unable to finish this portion of the lesson in class, you may want to assign the remainder as homework. 5. At the beginning of Day 2, facilitate a discussion with students in order for them to review all the statements on the handout. Ensure students have a good understanding of the material on the handout. 6. Include the following questions in the discussion: Which types of organisms receive their energy directly from the sun? (Producers) Where does all energy in an ecosystem ultimately come from? (The Sun) 7. Ask students to help you label each of the organisms on the class food web as a producer or consumer. Then, ask students to help you label each of the consumers as: herbivore, omnivore, carnivore, or detritivore. Require students to justify their choices to verify the class understands the labels. 8. Ask students to help you label each trophic level. 9. Post the following question for discussion: What is the importance of microorganisms within ecosystems? Answers may vary, but should include the concept that they help cycle nutrients from dead/decaying matter into living organisms. food web (on butcher paper, from previous Explore activity) markers (per class) Handout: Is it True? Ecosystems and Energy Flow (1 per student) Teacher Resource: Is it True? Ecosystems and Energy Flow KEY Check for Understanding: Use the class discussion to ensure students have a good understanding of these key vocabulary terms: producer, consumer, herbivore, carnivore, omnivore, detritivore, decomposer, and energy pyramid. Students should also be able to recognize various trophic levels. Instructional Notes: While students are completing the first part of this activity, circulate so you can determine areas of weakness that you may need to address during the discussion. When labeling the class food web, you may wish to have students take turns coming to the food web to label the organisms depending on class size and 2008, TESCCC 02/09/12 page 4 of 7

5 10. Allow students to record the definitions for these key terms in their science notebooks: producer, consumer, herbivore, carnivore, omnivore, detritivore, decomposer, trophic levels, and energy pyramid. available time. Consider having students label their food webs on the Handout: Food Chain Race (from the previous Explore activity). Misconceptions: Students may think that energy accumulates in an ecosystem, so a top predator has all the energy from the organisms below it. Students may think that a species high on the food web is a predator to everything below it. Students may think that producers receive their energy through the absorption of nutrients. STAAR Note: Supporting Standards B.11C and B.12DE and Readiness Standards B.12AC will be tested on the STAAR Biology Assessment. Notebooks: Students record definitions for these key terms in their science notebooks: producer, consumer, herbivore, carnivore, omnivore, detritivore, decomposer, and energy pyramid. ELABORATE Ecosystems and Energy Flow Suggested Days 2 (continued) and 3 1. Divide the class into groups of 3 4 students. Distribute the Handout: Ecological Pyramid Investigation to each student. Allow a few minutes to review the procedures of the lab and to answer student questions. 2. Distribute materials to each group. Instruct students to complete the investigation and all analysis questions (This may need to be assigned as homework). 3. On Day 3, facilitate a discussion in which students reflect on the results of the investigation. What are the effects on an ecological system if most of the producers die? Answers may vary slightly, but should address the concept that after a short amount time, many of the primary consumers will not be able to get enough food so they will either move to another location or die. Then, the same will happen to any secondary and tertiary consumers. resealable plastic bags (4 per group) calculator (1 per group) Optional Handout: Ecological Pyramid Investigation (1 per student) Teacher Resource: Ecological Pyramid Investigation Graphics (see Adv. Prep., 1 set per group) Teacher Resource: Ecological Pyramid Investigation KEY 2008, TESCCC 02/09/12 page 5 of 7

6 What are the effects on an ecological system if many secondary consumers die? Answers may vary slightly, but should address the concept that after a short amount of time, the primary consumers will increase in number because they are preyed on less. This, in turn, may result in lower numbers of producers because there are more primary consumers eating them. Finally, the number of tertiary consumers may decrease slightly because their prey opportunities are lessened. What are the effects on an ecological system if a large number of new producers are introduced to the system? Answers may vary slightly, but should address the concept that after a short amount of time, all of the consumers (primary, secondary, and tertiary) should increase. The primary consumers have more food and should be able to reproduce well, giving secondary consumers and tertiary consumers more prey to feed upon. Instructional Notes: Circulate as students complete the investigation and provide assistance if needed. The biomass numbers for this lab activity were adjusted for ease of calculations and are not actual biomass numbers for the organisms. Consider explaining this to students. Notebooks: Students affix their investigation handout in their science notebooks. EXPLORE/EXPLAIN Ecosystems and Energy Flow Suggested Days 3 (continued) and 4 1. Distribute the Handout: Nitrogen and Carbon Cycles Web Quest to each student. Students will visit websites and complete the handout (see Handout: Nitrogen and Carbon Advance Preparation). Cycles Web Quest (1 per student) 2. Circulate as students complete this activity and assist them as needed. Teacher Resource: Nitrogen and Carbon Cycles Web Quest KEY 3. Facilitate a brief discussion with students on the importance of both the nitrogen and carbon cycles. What happens to energy as it is passed from producers to consumers? (When energy is transferred from one organism to the next in a food chain, food web, or food pyramid, 90% of the energy is lost and only 10% of the energy is transferred. Therefore, an organism at the top of the food pyramid has to consume many organisms below it to have all its energy needs met.) Instructional Note: Students may work in small groups, rather than individually, if computer access is limited. How do chemicals cycle through ecosystems? Answers will vary but should include: nitrogen in the atmosphere nitrogen in decaying matter and waste nitrogen assimilating to animals nitrogen fixation by bacteria decomposition by bacteria and fungi denitrification and nitrification For carbon cycle: carbon dioxide in the atmosphere carbon dioxide in decaying matter carbon dioxide in fossil fuels underground plants use of carbon during photosynthesis animals obtaining carbon from plants animal respiration and plant respiration 4. Ask students to consider the consequences if either cycle is disrupted (This will be expanded upon further in Lesson 03. For now, simply introduce this concept). 2008, TESCCC 02/09/12 page 6 of 7

7 5. If time allows, you may wish to introduce the Evaluate portion of the lesson to give students more time for research on Day 5. EVALUATE Performance Indicator Suggested Day 5 Performance Indicator For two ecosystems, analyze and compare the flow of matter and/or energy using models such as various food chains, food webs, ecological pyramids, and the carbon and nitrogen cycles. Given an amount of energy for a particular trophic level, calculate the amount of energy in subsequent trophic levels using the 10% rule. (B.2G, B.2H; B.12A, B.12C, B.12D, B.12E) 1C; 4D; 5B 1. Refer to the Teacher Resource: Performance Indicator Instructions KEY and the Handout: Ecosystems and Energy Flow Project PI for information on administration of the assessment. poster board (2 per group) markers (per group) meter sticks (1 per group) Handout: Ecosystems and Energy Flow Project PI (1 per student) Teacher Resource: Performance Indicator Instructions KEY 2008, TESCCC 02/09/12 page 7 of 7