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. . Food, Energy, Growth and Michigan Dept. of Education New Directions teaching materials have been created tc help teachers develop scientific literacy and conceptual understanding for all of their students. As companions to the new Michigan Essential Goals and Objectives for K-12 Science Education, they illustrate the ideas about teaching, learning and curriculum that underlie the new objectives. Food, Energy, and growth is an 8th, 9th, and 10th grade unit designed to help students construct a clear understanding of the ways that food is used by our bodies for energy and for the materials needed for growth and repair. It has also been designed to help students learn to pose questions, search for solutions to problems, work together with others, and value the need for evidence in making decisions. Philosophy and Rationale Specifically, it illustrates the four important goals for science education listed in the Introduction and Rationale of the new state science objectives: 1) Scientific and for all students. Scientific literacy includes the ability to use scientific ideas to understand the world around us, to construct new ideas by asking questions and searching for answers, and to reflect on the adequacy of explanations and solutions. In this unit, students learn how to use the scientific ideas of cellular respiration and protein synthesis to explain how the energy needed for life activities and the materials needed for making new cells come from food, and they use the scientific ideas of structure and function to explain how the digestive and circulatory systems work together to provide the cells with what they need. As they do this, they sharpen their abilities to ask questions and construct answers, and reflect on the evidence needed to support arguments and decisions. Scientific literacy is not just for those who show an early interest in science or those who might pursue related careers. It is for all students. Because fewer and fewer young women and minority students develop an interest in science and technology, these New Directions units incorporate materials and approaches to support and encourage them in succeeding and staying in science. 2) Understanding over content coverage. To be scientifically literate, students need to have a deep and connected understanding of “the big ideas” of science. In this unit, those ideas include 1) that human digestive systems break down the components in food into several basic parts, some of which are building blocks of new cells, others are sources of energy; 2) that life activities occur in cells, and that those activities are primarily chemical in nature; 3) that human nutrition depends on eating correct proportions of food components; and 4) that various cultures have developed diverse diets, all of which provide the energy and materials that all people need. This kind of conceptual understanding takes time. That’s why these units are relatively long. For some teachers, the commitment of 6 to 8 weeks for one unit in science seems like a sacrifice of other important content. But to really understand the“big ideas,” students need to see how theoretical concepts, like “cellular respiration” and “protein synthesis” connect to the real world of Food, Energy and Growth TEACHER’S GUIDE i people eating--the fats, carbohydrates, and proteins in our food, our needs for energy and how they change during exercise, and what happens when we gain and lose weight. And they need to see how the concepts they learn make sense to them in terms of ideas they’re already familiar with, whether they have to do with agriculture or with chemistry. This kind of learning is fundamentally different from science teaching that skims across many topics, often overwhelming students with technical vocabulary. It is especially important for developing scientific literacy in all students. 3) Learning that is useful and relevant outside of school. Scientific literacy means an understanding of science that can be put to good use outside of school. For that reason, we have chosen topics for the New Directions teaching materials that connect scientific ideas, skills, and habits of mind with important “real-world” systems, events, and problems. But research continues to show that students bring to the classroom theories about how the world works that are sometimes at odds with scientific explanations. In this unit, for example, students often believe, naively, that the oxygen they breathe simply enters the lungs and is somehow transformed into carbon dioxide, without recognizing that oxygen is needed in the cells to chemically extract energy from the food they eat. One of the important goals of these new materials is to connect students’ developing scientific ideas with the ideas they already use to make sense out of the world. Sometimes this involves relatively little change; sometimes it involves “mind-bending” change. 4) Interdisciplinary teaching. The world is interdisciplinary. Botany alone, or physics alone, or economics alone, doesn’t provide answers to important social questions. And students shouldn’t see the world as compartmentalized, with language arts occurring between 9 a.m. and 10 a.m., mathematics between 10 a.m. and 11 a.m., and science only after lunch. These units draw from as many scientific disciplines as necessary to dig deeply into the topic. In this unit, human physiology, cell biology, chemistry, and nutrition are closely woven together. The unit also provides multiple opportunities for using and strengthening students’ expressive and quantitative abilities. On the whole, we hope that these units provide new resources to teachers for improving student achievement in science. The outcome we’re all striving for, though, is not just better test scores. What we really want are scientifically literate citizens. ii Michigan Department of Education About This Unit ..................................................................... vii ... "Cluster by Cluster” ............................................................... VllI Classroom Environment ........................................................ ix Table of Contents Supporting Young Women and Minority Students .............. ix State Science Objectives ......................................................... X List of Materialss ..................................................................... Xiv Preparing to teach Cluster 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . blue lab prep 1 WHY DO LIVING THINGS NEED FOOD? (AN INTRODUCTION) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . l Lesson 1 Food stores energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Lesson 2 What is in various Lesson 3 Where the action is: The cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Students observe energy released from a burning marshmallow and relate this to their body’s need for energy. . l l ., . \ thiJ 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Students identify the appropriate test for each of four food components (sugar, starch, protein and fat) and then use these tests to decide which of these nutrients are present in various foods. They discuss the need to eat foods that contain each of these components. Food, Energy and Growth After thinking about what cells are and where they can be found, students make a sand sculpture as an analogy to the cell structure of living things. TEACHER’S GUIDE ... 111 Preparing to teach Cluster 2 . . . . . . . . . . . . . . . . . . . . . . . . ...*..... blue lab prep 7 HOW DOES FOOD GET TO WHERE IT’S ~ USED? WHAT HAPPENS TO IT ALONG THE WAY“. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 l l l l Lesson 4 The food trip, part 1: The digestive tract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Lesson 5 Digesting foods: Where does it start? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Lesson 6 More on digesting foods: Breahing down proteins . . . . . . . . . . . . . . . . 22 Lesson 7 Getting food to the cells: Moving through tight places . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Students show what they know about the path of food in the human body by drawing the organs involved in this process on an outline of the human body and writing about it. Students either design an experiment or use the given instructions (testing oatmeal before and after it has been chewed for sugar) to explore the part of digestion that occurs in the mouth. Students use meat tenderizer and pineapple as a source of enzymes to digest the protein present in gelatin. They relate this to the actual digestion of protein in the body. Students use window screen with 1) sand and gravel and 2) gelatin and enzymes as a simplified model of digested food particles moving into the blood stream. l Lesson 8 The food trip, part 2: Taking a ride on the blood bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Students make a model of the small intestine, blood vessels, and cells, and use pictures of food particles to simulate digestion, movement of these particles into the blood vessels, and transport of digested food to the cells. l Lesson 9 The digestive and circulatory systems: Putting it all together . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Students complete the picture they made at the beginning of the cluster and write a story about the food trip as a way of solidifying what they learned in this cluster. Preparing to teach Cluster 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . blue lab prep 13 HOW AND WHERE IS FOOD USED IN HUMAN BODIES’,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 l iv Lesson 10 Breathing and exercise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Students discover what products are formed as the body uses energy and how they change with exercise. Michigan Department of Education l l l Lesson 11 ..................................................40 How your body actually gets energy from food Lesson 12 Growing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lesson 13 Weight gain and weight loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Students make and observe a burning butter candle. They compare the reactants and products of this energy-releasing process to the same process in their own body. They consider the chemical processes occurring in cells. 45 Students go back to the model of the digestive system they made in Cluster 2 and use the amino acids from digested foods to synthesize new protein. They make different arrangements of various numbers of amino acids to simulate the synthesis of different proteins, and discuss how organisms grow by adding new proteins to cell structures, resulting in cell division. Students analyze several hypothetical cases of weight gain and weight loss and decide what factors caused each effect. They make predictions for specific situations and develop plans by which they can attain their own weight goals. They chart a hypothetical person’s weight throughtout the day as materials enter and leave the body. Preparing to teach Cluster 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . blue lab prep 15 I l l DO WE GET WHAT WE NEED FROM ... WHAT WE EAT’,. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 Lesson 14 Diet and nutrition: What do you eat ? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Lesson 15 Diet and nutrition= What do others eat .? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Students explore the nutrition information on food labeling, categorizing various foods by their proportions of carbohydrates, fats, and proteins. They compare this information with the “Eating Right Pyramid,” and then analyze the eating habits of a fictitious character as well as their own. 64 Students consider and analyze healthful diets of vegetarians, and of other cultures that use less meat for their protein source. Appendices A. Unit content summary and student misconceptions B. Unit assessment C. Black line masters for student hand-outs and overhead transparencies Food, Energy and Growth TEACHER’S GUIDE V Scientific Literacy Scientific literacy is an understanding of the world around us that provides insights into how things work and why things happen. Scientifically literate people: are familiar with the natural world and respectful of its diversity and unity are skillful in constructing new personal knowledge through asking questions, gathering information, and thinking critically know key concepts and theories of science can describe, explain, predict and design systems, events or phenomena in the world around them using scientific knowledge are empowered by scientific knowledge and ways of thinking for personal and social awareness, problem-solving, and decision-making understand the nature of science and technology, recognizing their strengths and limitations recognize historical and cultural factors that shape science and technology continue learning throughout their lives, using scientific knowledge and ways of thinking. vi Michigan Department of Education “. Why are people becoming more “health-conscious” these days? Why are many trying to watch what they eat? Is it unhealthy to skip a meal and eat chips and pop instead? Why shouldn’t we eat pizza every night? What should we eat to be healthy? Why do people-and all living things-need food? How and where is it used in our bodies? How do the internal systems and organs in a human body work together to get what we need out of food? . About this Unit These are especially important questions because our well-being depends on making smart decisions about the foods we eat and other healthful activities we engage in, including exercise. We need to be able to listen critically to the claims we hear all around us about food and healthful behaviors, to analyze those claims in terms of their scientific merit, to find additional information when necessary, and then to make smart decisions. To make those decisions, students need to use scientificknowledge, in this case from both biology and chemistry. This knowledge includes the processes that occur in the digestive system of breaking down food into its constituent parts, the movement of food and oxygen through the body to all cells, and the use of food and oxygen in the cells for supplying energy and for building new materials that become part of our bodies when we grow. But being smart about food decisions requires more than knowledge about digestion and cellular respiration: Equally important, it requires certain skills and habits of mind-the ability to pose questions, to find necessary information, to set up tests; the disposition to demand evidence and logical reasoning in support of assertions, and to think critically about others’ claims; and the willingness to consider other ways of acting (other ways of eating, in this case) as reasonable and appropriate solutions to particular social or cultural conditions. This unit will help students develop this specific knowledge, and more general skills and habits of mind. Food, Energy and Growth TEACHER’S GUIDE vii Cluster By Cluster This unit is composed of four clusters, each building together a comprehensive story of the use of food and energy in humane--one of the key questions in the Framework of the new Michigan Essenfiral Go& and Objectives for& 12 Science Education. As a unit, these materials attempt to put the goals for Michigan science education into practice (see page 1, Philosophy and Rationale.) This is how the unit works: To develop a broadly-connected understanding of how organisms use food, this unit brings together cell-level, system-level, organism-level and community-level considerations about how food releases energy and provides materials for growth and repair. It cuts across traditional topics of human body systems, cell processes, and diet and nutrition, focusing primarily on life science issues but also dealing with bio-chemistry. To connect scientific theory to everyday life, these ideas are embedded in the important questions of what people need to eat to maintain their health-not only in middle class communities across the United States, but in diverse cultures both in the U.S. and in other parts of the world. Cluster 1 is an introduction to the unit. Its intention is to open up questions having to do with diet, growth, and energy; to provide an overview of why people need food; to establish the three major components of food (carbohydrates, proteins, and fats), and-although this is not a unit on cell specialization or cell reproduction-to locate where energy is actually extracted from food and where growth actually occurs: in cells. The first cluster does not present in detail the processes of extracting energy or using materialsthese are presented in Cluster 3, after Cluster 2 talks about the digestive and circulatory systems. Cluster 2 is about how the digestive and circulatory systems work together to distribute food components to the cells. Students trace a piece of food from when it enters the mouth until it reaches the cells, describinghowit is changed from plant or animal materials into essential substances that cells can use (simple sugars, amino acids, and fatty acids); how these substances pass through the digestive system into the circulatory system; and how they are distributed throughout the body. Cluster 3 takes a submicroscopic look at what goes on in cells, and relates the processes of cellular respiration and protein synthesis to human activities of energy use and growth. By the end of Cluster 3, students should be able to explain in detail the chemical process that occurs when cells extract energy from food, as well as the ways cells use materials from food for growth and repair of our bodies. Cluster 4 “puts it all together,” giving students opportunities to look carefully at what they eat and analyze whether their diets provide adequate nutrition for energy and growth. Students also look at what people in other cultures eat, and develop an appreciation for the healthy diets that other cultures have devised that rely much less on meat for protein. Cluster 4 is optional. Clusters 1 through 3 together provide good, sound biology; the material in Cluster 4 is often discussed in health classes. If your school decides that health class is the only place for diet and nutrition, at least you can be satisfied that your students will have the necessary biology to understand the rules they learn for healthful eating! ... vlll Michigan Department of Education Even though different teachers have different personalities, and different approaches to helping students learn, what’s common in classrooms where students are really making sense of science is studcnt activity -students working, students thinking, students explaining. “Hands-on, minds-on” means that doing and thinking are linked together in developing scientific literacy. Classroom Environment Classrooms where students are really making sense of science and learning to use its key ideas and habits of mind in their daily lives have a culture where students are continually trying things out, discussing their ideas, debating solutions to problems, being critical as well as open-minded, listening and thinking. Whether they are learning how to explain why something works, or how to describe a natural system in detail and show the connections of its parts, or how to use information to make predictions, or how to design and build a tool or a system, students have to be allowed to try out their ideas and explain their reasoning. And teachers have to value students’ thinking, both for the insight it provides to further a student’s development, and because it is the product of the student’s honest efforts to grapple with the important questions being raised in the class. In this environment of working, thinking, and listening to others, students learn that their ideas are important and valued, and that science is not authoritarian, dogmatic, and esoteric. Unfortunately, there are far more white males in scientific and engineering enterprises than women and members of minority groups, including African Americans, Hispanics, and American Indians. We say “unfortunately" because the contributions of women and minority persons to the scientific and engineering enterprises has historically been strong, even though they have Young Women been underrepresented by numbers. Supporting Clearly science and technology are fields that many persons can make strong contributions to, and that all persons should have the opportunity to choose. Many of our educational practices have pushed women and minority students away from science, though. and Minority Students in Science These materials, coupled with the best intentions of Michigan’s teachers, are attempting to provide support and encouragement for all students to take more science and mathematics courses and consider scientific and technical fields. Theyaredoingthis byintegratingculturally-relevant sciencematerials, reflecting the perspectives, experiences, events and interests of different ethnic groups relative to their roles in the scientific enterprise, into these teaching units. These culturally-relevant materials emphasize the social impact that all groups, including women, have had on mankind, and the significant consequences and implications for scientific improvement and achievement. We do this for several reasons. Integrated culturally-relevant examples will promote student pride in their ethnic, cultural and gender heritage, as well as provide an understanding and appreciation of how their culture influences the nature and structure of science. Also, all students need multicultural science education, even if they live in entirely white communities, in order to appreciate the full spectrum of ethnic diversity that exists in our society, in preparation for the day when they will most likely work along side someone of a different physical appearance and cultural background. Food, Energy and Growth TEACHER’S GUIDE ix State Objectives for this Unit Specific objectives for this unit, from New Directions for Science Education in Michigan: Essential Goals and Objectives are listed below, along with specific unit learning outcomes derived from each objective. The Constructing Scientific Knowledge and Reflecting on Scientific Knowledge objectives are integral parts of each New Directional. . Each Constructing objective and each Reflecting objective is woven throughout each unit, tied closely together with Using Scientific Knowledge objectives. Constructing Scientific Knowledge l l l X Pose questions about the composition and nutritional value of familiar foods and daily diets. Suggest appropriate tests for determining the composition of familiar foods, and design and conduct them. Use sources of information about the nutritional composition of foods (including food labeling) to analyze and make decisions about diets. Michigan Department of F.&cation Reflecting on Scientific Knowledge Justify the nutritional benefit of particular diets, based on evidence about foods’ composition and reasoning based on knowledge of cellular respiration and protein synthesis. Distinguish opinion from fact in claims about the nutritional value of certain foods. Articulate personal assumptions about diet and nutrition. 10) Recognize the convibutions .: .. cultures and Recognize the nutritional value of diets of other cultures which do not rely heavily on meat for their major protein source. Appreciate the ingenuity of other cultures in devising such diets. Describe contributions of food products from other cultures to typical U.S. diets. Food, Energy and Growth TEACHER’S GUIDE xi Using Scientific Knowledge . Explain how food is used by humans for energy. . Explain how food is used by humans for growth. . Analyze and describe food as made up of carbohydrates, fats and proteins. . Explain why humans need to breathe in oxygen. . Explain where the carbon dioxide comes from in the air we breathe out. . Explain how excess food consumed by adult humans is stored as . . . . tissue. Explain the role of minerals in human growth. Explain how humans gain weight. Analyze sample diets for proportions of food constituents. Construct diets beneficial for growth and energy needs. Objectives 5-7 Related concepts; terms .), and t o o l s ,’ , , :. ‘. real-world c o n t e x t s :.. ,‘,, :,;;jji:j,:,::,:c. .:j::. ““‘/ ; Trace the path that food follows as it moves from the mouth to the cells. Describe what happens to food as it travels through the digestive system, using words and pictures. Explain how food needs to be digested. Explain how oxygen reaches the cells. Explain how components of food reach the cells. Explain how the by-products of cellular respiration are removed from the body. Explain what happens to “leftover” food materials after digestion. xii Michigan Department of Education l l l l l l l l Explain the chemical process that occurs in cells to release energy from food. Explain why people need to breathe, and where oxygen goes after it enters the body. Explain where the carbon dioxide in our breath comes from. Explain why cells need energy. Explain how food helps people grow. Explain what happens when people gain or lose weight. Explain how cells use food to grow. Explain how the growth of cells is related to the growth of individuals. Food, Energy and Growth TEACHER’S GUIDE ... xln List of Materials for the Unit Cluster 1 Lesson 1, page 2 l l l Lesson 2: marshmallows shish-ke-bob sticks or something else to hold the marshmallows matches safety goggles 5 test tubes l a grease pencil l iodine solution l several foods: corn starch dissolved in water glucose (sugar) dissolved in water gelatin dissolved in water cooking oil l other foods for testing such as : banana, oatmeal, cooked egg white, potato, cracker,apple, spaghetti or noodles, cheese, and any other foods you want to bring from home to test. Food Test #l, page 5 l l safety goggles 5 test tubes l a grease pencil l Benedict’s solution l a boiling water bath (water boiling in a beaker, to place test tubes in) l several foods: corn starch dissolved in water glucose (sugar) dissolved in water gelatin dissolved in water cooking oil l other foods for testing such as oatmeal, banana, cooked egg white, potato, apple, spaghetti or noodles, cheese, and any other foods you to bring from home to test. Food Test #2, page 8 l l same set-up as for Food Test #l, except using biuret solution instead of iodine Food Test #3, page 10 Food Test #4, page 11 l l l Lesson 3, page 16 l l Xiv brown wrapping paper lamp foods to test, same as in other food tests (see above) wet sand a tray, dishpan, cookie sheet, etc. for containing the sand sculpture Michigan Department of Education Cluster 2 Lesson 4, page 18 l Lesson 5, page 19 l outline picture of human body (in appendix) uncooked oatmeal and a teaspoon to measure it Benedict’s solution and an eye dropper (why Benedict’s solution?) l test tubes l a boiling water bath l Lesson 6, page 22 3 Petri dishes without covers a stirring rod measuring spoon unflavored gelatin, set unseasoned meat tenderizer crushed fresh pineapple crushed canned pineapple l l l l l l l Lesson 7, page 27 I 5” by 5” piece of screen 250 ml beaker course sand (sand with variation in size of grains) unflavored gelatin, set unseasoned meat tenderizer l l l l l Lesson 8, page 31 l skematic drawing of cross-section of small intestine and blood vessels (in appendix) yam and markers of various colors, straight pins, glue or tape pictures of food molecules (abstract shapes - in appendix) l outline picture of human body (in appendix) l l Lesson 9, page 34 The 3-2-1 Classroom Contact video on the digestive system Digestion, The Inside Story) contains a good view of the small intestine and other parts of the digestive system, useful in this cluster. It is available from GPN, P.O. Box 80669. Lincoln. Neb. 68501,806-228-4630. Cluster 3 Lesson 10, Part 1, page 36 Lesson 10, Part 2, page 38 Lesson 11, page 40 . 150 ml Erlenmeyer flask . . . . . . 150 ml beaker straws bromthymol blue solution (BTB) Alka-seltzer tablets stopper, glass tubing and hose 50 ml graduated cylinder . . . . . stopwatch or clock with a second hand 150 ml beaker 50 ml graduated cylinder bromthymol blue solution straws l l l l L l l l Food, Energy and Growth butter cotton string Petri dish 250 ml Pyrex beaker scissors matches BTB solution TEACHER’S GUIDE xv Lesson 12, page 45 l model from Cluster 2 “molecules” of protein, fat, and carbohydrate (in appendix) pins l calculators l l Lesson 13, page 49 Cluster 4 Lesson 14, page 57 l copies of the Eating Right Food Pyramid (in appendix) copies of blank Pyramid (in appendix) chart of composition of various foods (in appendix) l chart of composition of various foods (in appendix) l l Lesson 15, page 63 xvi Michigan Department of Education Laboratory m Background Information for Cluster 1 Lesson 1 FOOD CONTAINS ENERGY P. 2 Students will perform a simple experiment that they are all familiar with but perhaps have never taken the time to think about and observe. They will light a marshmallow, watch it bum and make some observations about what is going on. Marshmallows, Shish-ke-bob sticks, or something else to hold marshmallow, splints and matches to light marshmallow PIT.FALLS AND CAUTIONS Always be very careful with fire. Large cans of sand should be placed around the room in case of an accident. Also, there should be containers of water in which students can drop their marshmallow in case it gets too hot to hold or if the stick they areusingbums. Tell students to hold the burningmarshmallow over the container of water so if the marshmallow gets soft and falls off the stick, the fire will be extinguished. Lesson 2 WHY EAT HEALTHFUL FOODS Since iodine changes to a blue-black color in the presence of a starch, it is possible to use this test to determine if starch is present in various foods. In Part A of this activity, students will perform the iodine test on a control (water) and on samples of a starch, a sugar, a protein (gelatin) and a fat. By comparing the color of the control with the color produced when adding the iodine solution to each of these nutrients, they will discover which ofthese nutrients changes color with the iodine solution. They will then use this information to test other foods to see if starch is present. FOOD TEST #l P 4 MATERIALS & PREPARATION Test tubes, 5 per student group (18 x 150 mm is a good size); grease pencils; iodine test solution; corn starch solution (1%); glucose solution (1%); gelatin solution (1%); cooking oil; foods for testing such as banana, cooked egg white, potato, cracker, oatmeal, apple, spaghetti or noodles, cheese, etc. and other foods students bring from home. Solutions must be made up in advance and will be used for testing food in several activities so you will want to prepare enough for future use. CORN STARCH SOLUTION Make a 1% solution by adding 1 gram of corn starch with a small amount of cold water while mixing. Continue adding water to bring the total volume to 100 ml. Heat the solution to boiling and allow to boil for 1 minute or until the starch is completely dissolved. Let cool. Food, Energy and Growth TEACHER’S GUIDE lab prep 1 SUGAR SOLUTION Make a 1% solution by dissolving 1 gram of glucose (also called dextrose) in water and then bring the total volume to 100 ml. Regular table sugar will not work for the sugar test done later in this lesson, but you can substitute fructose (fruit sugar or lactose (milk sugar). GELATIN SOLUTION Make a 1% solution by dissolving 1 gram of unflavored gelatin in water and then bring the total volume to 100 ml. Heat the solution until the gelatin has completely dissolved. IODINE TEST SOLUTION Iodine solution may be purchased from most chemical supply companies as Lugol’s iodine solution or you may obtain tincture of iodine from the local pharmacy. These solutions should be diluted by adding one part of the iodine solution with 5 parts of water. If you wish to make your own, dissolve 2 grams of potassium iodide (KI) in 100 ml of water. Add 1 gram of iodine crystals and stir until dissolved. PITFALLS AND CAUTIONS 1. In order to obtain good test results, foods tested initially should be white or light-colored. This allows the color of the iodine to show up clearly. 2. Color should be observed where ever the iodine solution comes in contact with the food. It is not necessary for the whole contents of the test tube to change color. 3. Iodine, though in very dilute solution, can be harmful and should be handled with great care. If spilled wash with plenty of water. 4. Students should be encouraged to bring foods of their own choosing from home. Allow them to investigate foods of any color. They should discover on their own that it is sometimes difficult to tell if the iodine gave a positive test. 5. Iodine will discolor in any of the unsaturated oils. This should not interfere with the students ability to determine that the test clearly was not positive. 6. Don’t use small test tubes as the food will get stuck and they will be difficult to clean. FOOD TEST #2 P. 8 lab prep 2 Some sugars, called reducing sugars, will react when heated with Benedict’s solution to produce colors ranging from yellow-green to red-orange. This activity allows the students to use this test to find out whether a reducing sugar is present in various foods that they eat. In Part A they will perform a test with Benedict’s solution on a control (water) and on samples of a starch, a sugar, and a protein (gelatin) and fat (cooking oil.) By comparing the color produced when adding the Benedict’s solution to each of these nutrients with the color of the control, they will discover which of these nutrients changes color with the Benedict’s solution. They will then use this information to test other foods to see if sugar is present. Michigan Department of Education MATER IALS & ADVANCE PREPARATION Test tubes, 18 x 150mm (5 per group); test tube holder; grease pencils; hot water baths; Benedict’s solution; corn starch solution (1%); glucose solution (1%); gelatin solution (1%); cooking oil; foods for testing such as oatmeal, banana, cooked eggwhite, potato, cracker, apple, spaghetti or noodles, cheese, etc. and other foods students bring from home. Most of these solutions were used in the preceding activity. Be sure you have enough of each solution for this activity. You will need to prepare the Benedict’s solution in advance. It will be used for testing food in future activities so you will want to prepare extra. CORN STARCH SOLUTION See p. “lab prep 1” SUGAR SOLUTION See p. "lab prep 2” GELATIN SOLUTION See p. “lab prep 2” BENEDICT’S TEST SOLUTION Benedict’s solution may be purchased from most chemical supply companies or you may make your own. Dissolve 173 grams of sodium (or potassium) citrate K!,H,N%O,l and 100 grams of anhydrous sodium carbonate (Na.$O,) in 800 ml of water. (Note: Instead of anhydrous sodium carbonate, you may use 200 grams of hydrated (crystalline) sodium carbonate.) Heat the solution gently to speed dissolving. Filter the solution. Stir constantly while adding to this solution, 17.3 grams of copper (II) sulfate pentahydrate (CuS0,‘5H,O) which has been dissolved in 100 ml of water. Add enough water to bring the total volume to 1 liter. PITFALLSAND CAUTIONS 1. In. order to obtain good test results, foods should be white or nearly white. This allows the colors of the reaction to show up clearly. 2. A positive reaction in this test can yield colors ranging from yellow to red to blue and all possible mixtures of these colors. It is not necessary to determine why different colors form. Students should simply know that each of these is a positive test. 3. Benedict’s solution, though very dilute, can be harmful and should be handled with great care. If spilled wash with plenty of water. 4. A boiling water bath is most easily set up by placing a beaker of water on a hot plate to boil. Test tubes are placed in the beaker ofboiling water. Water should be boiling gently, not vigorously. 5. Students should be encouraged to bring foods from home. Allow them to investigate all of these foods. You may need to remind them that sometimes the color of the food interferes with the color of the test. 6. Some foods may not give a positive test result even though you and the student know that it contains sugar. This is because there are some sugars that are not sensitive to this test. There are other tests that can detect these Food,, Energy and Growth TEACHER’S GUIDE lab prep 3 other sugars. 7. If smaller test tubes are used, the food may get stuck and cause problems cleaning them. FOOD TEST # 3 p_ 10 This activity allows the students to find out whether protein is present in various foods that they eat by adding Biuret solution to various foods. In the presence of certain proteins, Biuret solution will turn a pink to purple or violet color. In Part A, students will perform the Biuret test on a control (water) and on samples of a starch, a sugar, a protein (gelatin) and a fat (cooking oil.) By comparing the color produced when adding the Biuret solution to each of these nutrients with the control, they will discover which of these nutrients changes color with the Biuret solution. They will then use this information to test other foods to see if protein is present. MATERIALS & ADVANCE PREPARATION Test tubes, 5 per group (18 x 150mm); grease pencils; Biuret test solution; corn starch solution (1%); glucose solution (1%); gelatin solution (1%); cooking oil; foods for testing such as banana, cooked egg white; potato, cracker, apple, spaghetti or noodles, cheese, etc. and other foods students bring from home. Most of these solutions were used in the preceding two activities. You will need to check to be sure there is enough of each solution for this activity. Biuret solution was not used before. Solutions must be made up in advance and will be used for testingfood in several activities so you will want to prepare extra. Directions for preparing all of the solutions are given below. CORN STARCH SOLUTION See p. "lab prep 1” SUGAR SOLUTION See p. “lab prep 2” GELATIN SOLUTION See p. “lab prep 2” BIURET REAGENT: Biuret solution may be purchased from most chemical supply companies or you make your own. Dissolve 3 grams of copper sulfate (CuSO,*5H,O) and 12 grams of potassium sodium tartrate (KNaC,H,O,; also called Rochelle salt) in 1 liter of water. Next prepare a second solution by adding 60 grams of sodium hydroxide pellets (NaOH) very slowly with stirring to 600 ml of water. CAUTION: Use Pyrex glassware as this reaction generates a large amount of heat. Stir constantly while slowly adding the sodium hydroxide solution to the copper sulfate solution. PITFALLS AND CAUTIONS 1. In order to obtain good test results, foods should be white or nearly white. This allows the color of the Biuret solution to show up clearly. 2. Color should be observed where ever the Biuret solution comes in contact lab prep 4 Michigan Department of Education with the food. It is not necessary for the whole contents of the test tube to change color. 3. Biuret, though in very dilute solution, can be harmful and should be handled with great care. If spilled wash with plenty of water. 4. Students should be encouraged to bring foods from home. Allow them to investigate all of these foods. You might want to encourage them to make predictions about whether the nutrient for which they are testing is present in each of the foods they test. There will probably be some surprises! 5. Food may get stuck in smaller test tubes and make cleaning up more difficult. In this activity, the students will investigate whether various foods contain fats. This test is done placing a drop of the food to be tested on brown wrapping paper and smearing it around with your finger or by rubbing a small amount of the food to be tested directly on the brown wrapping paper. The paper is then allowed to dry and is held up to a light to see if light passes through it. FOOD TEST #4 p. 11 MATERIALS & ADVANCE PREPARATION Brown wrapping paper cut into squares approximately 2” x 2”, gooseneck lamp or other light source, corn starch solution (1%); glucose solution (1%); gelatin solution (1%); cooking oil; foods for testing such as banana, cooked egg white; potato, cracker, apple, spaghetti or noodles, cheese, etc. and other foods students bring from home. Most of these solutions were used in the preceding two activities but you will need to check to be sure there is enough of each for this activity. Solutions must be prepared in advance. CORN STARCH SOLUTION See p. “lab prep 1” SUGAR SOLUTION See p. Yab prep 2” . GELATIN SOLUTION See p. “lab prep 2” PITFALLS AND CAUTIONS 1. If the food contains only a small amount of fat, it may not be detected in this test. If no fat has been detected, you may allow the students to investigate further by dissolving a small amount of the food in a few ml of rubbing alcohol. Allow the food to dissolve for about 5 minutes. Then pour the solution onto a piece of brown paper and allow to dry. Then check for a translucent spot on the brown paper. 2. Brown paper bags work well for this test if you avoid using the parts of the bag with printing on it. ’ 3. The light source works well as a heat source to dry the papers. Place a few inches from the paper after the food has been rubbed very hard into the paper. Food, Energy and Growth TEACHER’S GUIDE lab prep 5 4. Students should be encouraged to bring foods from home. Allow them to investigate all of these foods. You might want to encourage them to make predictions about whether the nutrient for which they are testing is present in each of the foods they test. There will probably be some surprises! Lesson 3 SAND SCULPTURE P. 14 This activity is designed to get students thinking about cells as the building block of all living things. Often students will tell you that all living things are made up of cells but upon further probinginto their thinking about where cells can be found, they might say in the skin and blood. When asked about bone, hair, heart, muscle etc., they will frequently hesitate and then either say “No” or “I don’t know.” The similarity of cells in all living things and grains in the sand sculpture should help them realize that all living things are made ENTIRELY of cells; and like the grains of sand, the cells of living things differ. There are skin cells, blood cells, muscle cells, nerve cells, etc. Fine sand and water; trays of some kind to build the sand sculpture on, so that sand doesn’t get all over the desks and floors (styrofoam meat trays, cafeteria trays, aluminum trays students bring from home, etc.) PITFALLS AND CAUTIONS 1. Students may think they are too sophisticated for this activity and they may have a hard time getting started, but as soon as they begin they usually get into the creativity of their sculpture quickly. It is important that they do not lose sight of the comparison between grains of sand and cells of living things. Going around the room and asking questions to individual students will help keep the focus on the lesson. 2. You or one of your students may want to bring a camera and take pictures of some of the sculptures to display around the room. lab prep 6 Michigan Department of Education WHY DO LIVING THINGS NEED FOOD? PytJ 1 ti 0 Many questions are posed in this unit simply to stimulate class discussion. Questions marked with numbers are ones that students should write answers to. We recommend that students use a joumals or “science log” for writing answers to questions so they can refer back to their earlier ideas when appropriate. They can also use the journal for recording observations and data from lab activities. Think about your favorite meal. Think about all the foods you can buy at the grocery store or a farmers market. Think about all the foods advertised on T.V. Why do you eat the foods you eat? Why does anyone eat food? What happens to people when they don’t get enough good food? What happens when they eat too much "bad” food? Think of all the foods that are “good for you” that you don’t like, and all of the "junk foods” that you do like. Whafs the difference between "good” foods and “junk” foods? - The Key Questions in this unit are the “objectives” for each cluster or lesson. When they are first presented in the cluster or lesson, they are for stimulating discussion, activating students’ prior knowledge, and giving anideaofwhat’s ahead. Don’t ask for or give definitive answers at this time-they will be developed during the cluster. But do ask students to voice their present ideas. This will give you some insight into their thinking, and perhaps stimulate some initial debate and questions that will carry through the cluster. - Why do people--and all living things-need food? 0 I(ey Questions What's the difference between “good” foods and “junk” foods? Where is food used in our bodies? 1 Food, Energy and Cmwth Food, Energy, and Growth TEACHER’S GUIDE Lesson 1 9 FOOD STORES ENERGY We eat for many reasons. The most important is energy. All living things require energy for life activities. People need energy to run, to talk, to lift, to smile, to wink-anytime we move our muscles and bones. We need energy to pump blood through our body (the heart is a muscle, too!) We need energy to send nerve signals around our bodies, and to repair parts of our body when we’re injured or sick. Food stores the energy we need for all of these life activities. Allow students time to puzzle about this. You might want to write their ideas on the board. If students come up with a good approach, let them try it. Can you think of something you could do to show that food stores energy? Try This If you have roasted marshmallows before, you know how quickly they will catch on fire. Would burning a marshmallow show that the marshmallow stores energy? What do you think? You might want to try burning a marshmallow again, just to remind yourself of the experience. To try it, you will need a marshmallow, a shish-ke-bob stick or something else to hold the marshmallow, and matches. Be very careful to keep the flaming marshmallow away from everyone’s hair and face. A. Light the marshmallow and watch what happens. Record observations from all of your senses (sight, smell, hearing, touch, and taste.) 1. More light and heat are given off when the marshmallow bums than the match gave off. This energy must have come from the: marshmallow. 1. What evidence do you have that marshmallows store energy? 2. a) When the marshmallow burned, did it give off more energy (more light and heat) than the match did that was used to light it? 2. There is extra energy that did not come from the match, since the marshmallow bums longer. This energy comes from the marshmallow itself, not the match. It is not produced by the marshmallow, but is released during the chemical change of burning. b) Where do you think all that energy came from? 2 Michigan Department of Educa tion Lesson Statement: Students wilI observe energy released from a burning marshmallow and relate this UI their body’s need for energy. Lesson 1 TG2 Purpose: To introduce the concept that food provides all the energy needed for all ‘“life activities.” Approximate Time: 1 class period See Advance Preparation for this lesson, in blue pages prior to this cluster. Michigan Department of Education The heat and light that you see during burning are forms of energy that are released from the marshmallow as it burns. What do you think is happening inside your body when a marshmallow g i v e off its stored energy? Are there little flames burning inside your body giving off heat and light? Probably not. But energy is being released all the time from the food you eat. Some is heat that keeps your body temperature close to 98.6. F. Some energy your muaclea work. Some sends signals through your nerves to your brain. All of your body’s functions require energy. Imagine this Writing Imagine that you and two companions are traveling in a small boat in the middle of Lake Michigan. Your boat rune out of gas just when you come to an uninhabited island. You pull into shore and decide the best thing to do is wait for help to arrive, but that could take several days or even weeks. You might want to have your students write a short story about survival on this island Have them focus on the food questions, but let them explore other aspects of survival, too. You have no food. You have to survive off the land. You and your friends must decide how to obtain food for this period of time. 3. How might you decide which things would be good sources of food and 4. List food supplies you would be likely to find on this island. 3. Tbe main idea of this qucstion is that all food comes plants or animals that cat plants. 6. List aa many “life activities” as you can for which your body would need energy. 4. Fruits, nuts, certain roots, stems and leaves; fish rabbits, deer, etc. 6. Where would you say that energy in the food you eat (including in the marshmallow) came from originally? 5. Eating, walking, running, etc. arc common answers; try to encourage answers that arc not so common, such as winking, smiling, breathing, etc. which would not? * * * One of the main reasons we eat is to get the energy we need for moving, thinking, pumping blood around our bodies, talking, smiling, and all other life activities. But is all the food you eat used for energy? Lesson 2 is about what is in various foods. All foods are made up of different combinations of a few common types of substances: proteins, carbohydrates, and .a To understand how you grow and get energy, you need to know about these different types of food components. That’s what the next lesson is about! 6. All foodcomes directly or indirectly from plants. Most students will know aboutfoodchainsorwebs;theimportant i&a for this unit is that plants store energy from the sun in food making tbc sun’s energy available to humans and all other animals. 3 Food, Energy, and Growth Lesson 1 Food, Energy, and Growth TEACHER’S GUIDE TG 3 W H A T IS IN VARIOUS FOODS? Lesson 2 You probably know that children and young people need to eat healthful foods so that they will grow. But what are healthful foods? Is pizza healthful? Are hamburgers healthful? People have many different opinions about which foods are healthful. But there’s one way to know for sure. Ask yourself two questions: Is this food a good source of energy? Is this food made up of the things that will help me grow? Discuss the Key Questions; perhaps write various answers on the board, brainstorming; or have students write their own answers. The purpose is to make students aware of the beliefs that they presently hold, and get them to begin to reflect on their adequacy. More-complete answers will be developed as the unit progresses. Many students will say, at this point in the unit, that we need to eat healthful foods “because they help us grow,” without giving any explanation of what they do inside our bodies (how we use food.) As the unit progresses, they need to improve their explanations to include the functions of food in our bodies. But how can you know if a food is a good source of energy, or is made of the things you need to grow? What’s the difference between good foods and "junk" food? Questions How could you find out which is which? If you said that good foods help you grow big and strong, and junk foods don’t, that’s OK. But don’t you want to know why? If you said that we can’t eat only junk foods like candy bars or cookies because they are mostly sugar and can cause cavities or because they have too much fat and that’s bad for us-don’t you want to know why? If you said that we can’t eat just fruit because we won’t get enough protein, or because maybe there’s not enough of something in it that we need-don’t you want to know why we need protein? That’s what this unit is about: finding out why we need to eat healthful foods. The short answer is: It’s important to eat different kinds of foods because they contain different kinds of materials our bodies need for energy and for growing. What are these different kinds of materials? What are foods made of? We don’t mean like a pizza is made of cheese, bread dough, tomato sauce and toppings, or like bread dough is made of flour, salt, sugar, baking soda, oil and yeast. But what are the components of flour, what are the components of cheese, what are the components of the basic foods we eat? 4 Michigan Department of Education Lesson 2 TG4 Michigan Department of Education All foods are made up of a few different components The three major components in food are carbohydrates (which include sugar and starch), fats, and proteins. Where have you heard of these before? Can you think of some ways to tell which of these materials make up different foods? Try This Scientists have ways of telling whether or not carbohydrates, fats or proteins are a part of different kinds of food. They use special chemicals that turn color when carbohydrates, fats or proteins make up a certain food. You can do the same tests that scientists use to find out what kinds of substances are a part of the foods you eat. Many students have heard of these before in health class or by reading labels from food packaging. Some may have done the food tests before. Other components of food beside carbohydrates, proteins, and fats including vitamins and minerals, a n d fiber. Vitamins and minerals make up much smaller percentages of food than carbohydrates, proteins and fats, but are still essential for many different body functions. You will perform four different tests on several different foods. Two of these tests are for carbohydrates (one for sugar, and another for starch, both of which are carbohydrates), one is for fats, and one is for proteins. We won’t tell you which one you’re doing. You can figure out which is which as you go along. Food Test #1 For all of these tests, we will start with four very simple foods, and then use a few more foods that you can bring from home. This will allow you to test some of your favorite foods. You will need: * safety goggles * 5 test tubes l agreasepencil * iodine solution * several foods: corn starch dissolved in water, glucose (sugar) dissolved in water, gelatin dissolvedin water, cooking oil. l other foods for testing such us: banana, oatmeal, cooked egg white, potato, cracker, apple, spaghetti or noodles, cheese, and any other foods you want to bring from home to test. Each of the tests that follow have two parts. The first parts are samples of food that have only one component. The second part uses more complex “‘every day” foods. To save time, you could do the first part of each test as a class demo. We recommend that you stilt allow students to figure out which test is for which food component, rather than simply telling them this. Most students do not think of the simple test substances (corn starch, glucose, gelatin and cooking oil) as foods. They might need to be reminded that, even though we don’t eat them straight, they are also foods. To keep track of which food you are testing, you will need to put different foods in separate test tubes and mark each test tube to tell them apart. 5 Food, Energy and Growth to begin to consider why some foods are “junk” foods, and others are more important for gI+OWth, Approximate Time: 1~2classperiodsforeachtestdepen~ngMw~theinitial testsaredoneasdem~tions~studentIdbs,andhowmanyfoodsafeused. is 4 to 8 class periods. LJ ?‘otaMne See Advance Preparation for this lesson in the blue pages prior to this cluster. Food, Energy, and Growth TEACHER’S GUIDE Lesson 2 A. Use a grease pencil to number five test tubes, 1 through 5. Then make a line 2 cm from the bottom on each of these test tubes. B. Fill the test tubes to the line with the following substances: water (wed as a control) corn starch solution (starch) glucose solution (sugar) gelatin solution (protein) cooking oil (fat) Test tube #l: Teat tube #2: Test tube #3: Test tube #4: Test tube #5: C. Create a chart in your journal for recording your observations, something like this: substance to be iodine solution test results tested The extra rows and columns are for additional foods (rows) and additional tests (columns). There arc a total of four different food tests. (color) water corn starch solution glucose solution gelatin solution cooking oil D. Notice and record the color of the iodine solution. Lab db Q safety The test solutions car irritate your eyes and skinr’n, skin B e very careful not to spill them on yourself or others. Rinse in plenty of water if you spill any. Get help from your teacher. E. Test each food (and the control) by adding a few drops of the iodine solution to each of the five test tubes. Observe and record the color of each food after the iodine has been added to it. 6 Michigan Department of Education Lists of foods: Yourclassshouldbegin cl Lesson tokeeplistsoffoodsthatcontainsignificantamounts of sugar, carbohydrates, protein and fat. We want students to develop a familiarity with the major components of food (for example, that chocolate candy contains sugar and fat; that bread, cereals and pasta contain starch or complex carbohydrates; that meats contain protein, etc.) 2 TG6 Michigan Department of Education 1. The first test tube, which contained water, was used as a control. How did the color change when the iodine was added? Is this a new color? 2. Which test substances changed the color of the iodine solution? What color did it turn? 3. Based on your observations, which component of food (starch, sugar, protein, or fat) is the iodine test used to detect? Why do you think that? 4. How could you tell if this component is present in a food that you might eat for dinner? The control did not change the color of the iodine-it only made it lighter because the water diluted the iodine a little. Water is used as a control because it shows what happens to the test solution when it is added to a test tube with no starch, protein, or carbohydrate. *** Food Test #l with Other Foods Now try testing some other foods. Test foods that you like, or that you want to know more about. 1. The color got slightly lighter. Itisnot a new color, only diluted; no chemical change has taken place. Students may need to be told that-for these tests-it doesn’t matter how dark or light a color is: dark blue and light blue are still blue, only the light blue is diluted by more water, which doesn’t change the test. 2. Starch; the color changed to dark blue or black, depending on how much starch was present. 3. Starch. It reacts with the iodineturns color in the iodine test. 4. You could test a sample of your food with iodine and look for a color change. (Some students may know that you can find this information on food labels.) F. Keep test tube #l as a control. Use it to compare colors to see if a reaction occured. Clean test tubes #2, #3, # 4 and #5. You need clean test tubes to make sure that none of the first foods contaminate the next foods you test. G . Repeat the iodine test on four new foods. You should use foods that are mostly white or pale, so you can see the color change easily. Try: mashed banana chopped cooked egg white oatmeal marshmallows Record your observations in your journal. Make sure that you test oatmeal. It is used again in lesson 5. H. Select at least three other foods provided by your teacher or that you brought from home. Test them for the presence of starch. Record your observations on your journal. Food, Energy and Growth 7 How test solutions work: Indicator solutions work by actually reacting withthecomponent of food that they tcst for, crcating a new substance of a different color. This is a chemical reaction. If the substance that they test for is not present in the food, there will be no reaction, and therefore no color change-although if the substance being tested has a good deal of water in it, it may make the color of the test solution lighter, by diluting it. This is why a control is important mportant to see what color the test solution becomes when it is diluted with water, but when it does not react. Food, Energy, and Growth TEACHER’S GUIDE a Lesson 2 -Ix;7 5. Which foods tested “positive" How do you know? 5. Crackers, bread, pasta, oatmeal, marshmallows, etc. test positive for starch because the iodine solution turns 6. What does the positive test tell you about the food you tested? to dark blue or black. 7. Why would it be difficult if we test this on blueberries? 6. These foods contain starch. 7. They are already dark blue so the change in the color of the iodine would be very difficult to detect. Some students may think blueberries are blue because they contain starch. Not true. Blue is the color of the food. 8. Purple grapes, raisins, chocolate, etc. 8. On what other foods might it be difficult to test? *** Food Test #2: If it’s not starch, then what is it? Scientists use two other tests that are similar to the one you just did. These two other tests show if foods contain sugar (another kind of carbohydrate) or protein. Both use chemical solutions that change color if the sugar or protein is present. Set up this next set of tests in the same way you set up the iodine solution tests. The only difference is that this new test solution-called Benedict’s solutionworks only when you heat the food to be tested in boiling water. You will need: l l l 8 safety goggles 5 test tubes a grease pencil TtestttestestTtesthe solutions can irritate your eyes and skin. Be very carefulnot to them. f Rinse in plenty of water if you spi11 any. Get help from your teacher. Michigan Department of Education Llesson 2 TG 8 Michigan Department of Education A. Use a grease pencil to number five test tubes, 1 through 5. Put your initials on the top of each test tube. Then make two lines, one 2 cm from the bottom on each of these test tubes and another line 4 cm from the bottom of the test tubes. You will add food to the first line and the test solution to the second line. B. Fill the test tube to the first line with the following substances: Test tube # l : water Test tube #2: corn starch solution Test tube #3: glucose (sugar) solution Test tube #4: gelatin (protein) solution Test tube #5: cooking oil (fat) C. Now add enough Benedict’s solution to each of the five test tubes to fill it to the second line. D. Place the test tubes in a boiling water bath for three to five minutes, or until you see a distinct color change. Then observe the color in each of the five test tubes. Compare the color with that of your control (water.) Record your observations in your journal. You may simply add another column to your chart to record your observations. E. Now do the same test with four other foods-mashed banana, chopped, cooked egg white, oatmeal, and marshmallow. Look back at the directions for using Benedict’s solution, and follow them carefully. F. You may test other foods if you like-some of your favorite foods, or foods you consider either healthful or “junk.” Just keep a record of your tests in your journal. 9. The first test tube, which contained water, was used as a control. What color was it after adding the Benedicts solution? 10. a) Compare the color of the control test tube with each of the other test tubes. Which test substances changed the color of the Benedict’s solution? b) What color did it turn? 11. Based on these observations, what component of food does the Benedict solution test for? 9 Food, Energy and Growth 9. Light blue 10. a) Glucose or sugar b) Red to orange to yellow to green to brown. All of these colors represent positive tests for sugar. In case someone asks, the different colors are caused by different kinds of sugars. 11. Glucose (sugar) 0 Lesson 2 L’ Food, Energy, and Growth TEACHER’S GUIDE TG 9’ 12. a) Which foods in the second set reacted with the Benedict’s solution? 12.a) bananas, crackers, marshmallows, etc. b) Did they all turn exactly the same color? b) No, some turn reddish, others c) Can you explain any differences? greenish. c) Actually, different kinds of sugar turn different colors. But students may suggest that different amounts of sugar or heat cause the different colors; or they may come up with other interesting ideas of their own. 13. They all contain glucose (sugar). 13. What can you conclude about the foods that gave a positive test? *** Food Test #3: If not for starch or sugar, then what? There’s one more test that scientists use that is similar to the one you just did. It uses a chemical test solution called biuret solution. Think about the four main components of food that you have been testing: sugars, starches (both carbohydrates), proteins, and fats. Which two have you already used a test for? Which two could this new test be for? In letting students set up their own experiments here, we are trying to help them become more proficient in the “Constructing new knowledge” objective of “Design and construct For this test, no written directions are provided. You have been through these kinds of tests at least four times now, and you can probably set up these tests fairly well yourself. ,/ ‘\ scientific investigations.” .- _-_ 0 , /’ -- Biuret solution tests for protein. It turns pink to purple to violet. You may need to place a piece of white paper behind the test tube to notice a color change. ---8,’ First, create a new record page for recording your resulb. Set it up with a table similar to the ones you’ve used already. _’ . .._. .\~ - Then, set up the test foods, using the four simple substances in addition to the control (water). Remember that test solutions can irritate your eyes and skin. Be very careful not to spill them on yourself or others. Rinse in plenty of water if you spill any. Get kelp from your teacher. db Q You need to add at least 10 drops to each test tube, but you do not need to heat the foods in this test. If will be helpful if you use a white piece of paper for a background when comparing the colors of the foods to the color of the control. When you have discovered which main food component the biuret solution tests for, make a note in your journal. Then conduct the biuret test again on new foods such as mashed banana, oatmeal, crackers, marshmallow, egg white, and any other foods you might have brought from home. Record your observations and conclusions in your journal. 10 Michigan Department of Education Lesson 2 TG 10 Michigan Department of Education Food Test #4: This one’s different! d How can you test for another component offoods-fats? The test for fats is much simpler to perform, but it only works well only with a ’ high-fat content food sample. 62 L , All you need is brown wrapping paper, a lamp, and food to test. Begin by testing the simple substances you used earlier: glucose, corn starch, gelatin and cooking oil. A. Get samples of each of those foods. Also obtain several small samples of other foods for testing, such as banana, cooked egg white potato, cracker, oatmeal, apple, peanut butter, cookies, spaghetti or noodles, cheese or other foods. B. Prepare five pieces of brown wrapping paper, approximately 2” x 2”. Label each piece of paper with the name of the food substance to be tested: #l: water #2: corn starch solution #3: glucose (sugar) solution #4: gelatin (protein) solution #5: cooking oil (fat) C. Use a stirring rod or eye dropper to transfer a few drops of each test solution to the appropriate piece of brown paper. D. Allow the test spots on each sheet of brown paper to dry. When thoroughly dry, brush dried particles off the paper and hold the paper up to the light. Compare each of the papers with the control. The property of light passing through the paper is called translucence. Note whether light passes through the paper. Record your observations in your journal. Save the papers for comparison in the next part of this lab. E . Obtain several more sheets of brown paper. Label them with the names of the following foods: #6: mashed banana #7: chopped, cooked egg white #8: oatmeal #9: marshmallow Food, Energy and Growth 11 How much fat is too much? A certain amount of fat is needed by our bodies for the production of certain cell structures. But “most health authorities recommend an American diet with less fat, saturated fat, and cholesterol. Populations like ours with diets high in fat have more obesity and certain types of cancer. The higher levels of saturated fat and cholesterol in our diets are linked to our increased risk of heart disease. “A diet low in fat makes it easier for you to include the variety of foods you need for nutrients without exceeding your calorie needs, because fat contains over twice the calories of an equal amount of carbohydrates or protein.” Home and Garden Bulletin No. 232, U.S. Department of Agriculture, U.S. Department of Health and Human Services, 1990. Food, Energy, and Growth TEACHER’S GUIDE sl Lesson 2 TG 11 F. Now use your finger to rub each of these foods on a spot on the appropriate piece of brown paper. Be sure to use a different finger or wash your finger before handling each food. You must rub very hard as you are trying to press food into the paper. Allow the paper to dry for a few minutes. The spot will dry more quickly if you use a lamp placed about 2 inches above the paper. When dry, brush off any dried particles. Hold the paper up to the light and note whether the spot is translucent (as it was before in the presence of fat). Compare the results with your samples in part A. Record the results in your journal. G. You may test other foods if you like. Keep a record of your tests in your journal. 14. You can detect fat because it is the only one that soaks into the paper and makes the light pass through the paper. 14. Based on your observations of the way the four simple foods and the control reacted with the paper, which of the four components can you detect using the brown paper test? Explain your reasoning. 15. Some foods that contain fat are 15. Which of the additional foods you tested contain this component? cheese, egg yolk, nuts, potato chips, hot dogs and other meat, etc. Many students will be surprised to find fats in some of the foods they tested. 16. On the basis of the tests you have performed in this and the last three activities, which foods that you tested could be a good source of a) protein? b) starch? c) fat? d) sugar? 16. Answers will vary but some typical answers are: a) egg, cheese, turkey and other meat. b) crackers, pasta, potato, bread c) cheese, nuts, red meat 1’7. a) Which foods contained more than one component? b) Are you surprised by any of these? Why? d) fruit, cookies, marshmallows 18. a) Did any of the foods contain all 4 components? 17. a) Again answers will vary. Most foods contain more than one nutrient. Typical answers might include marshmallow (starch and sugar), crackers (starch, sugar and fat), banana (starch and sugar and maybe fat) b) Are you surprised by any of these? Why? b) Answers will vary. 18. a) Possibly nuts or cheese. b) Answers: will vary. 12 Michigan Department of Education Lesson TG 12 Michigan Department of Education So why is it important to know what’s in foods? ,, Now that you have completed your food tests, you know that some foodshaveonly protein, some have only fats, some have onIy starch or ,sugar, but most have combinations of two or more of these components. In order to grow and obtain energy, your body must have all of these.subst substances ancs Your body uses many carbohydrates and fats for their stored energy, Your body uses proteins to build new body parts when it grows or when it repairs itself. The materialsin food actuallybecome part of our bodies whenwe grow and gain weight We also use proteins for energy if we need energy beyond our carbohydrate and fat supplies. See note on p. TG 48 about vitamins and minerals. But your body doesn’t need each of these components in equal amounts! Many Many of us tend to eat too many foods with lots of sugar and fat (which we need only in limited quantities) and not enough of the starches and protein (which we need more of!) 19. a) Use what you have learned to write answers to the two key questions at the beginning of Lesson 2: What’s the difference between good foods and “junk” foods? How could you find out which is which? b) How are your answers different now than when you first thought about these questions at the beginning of the lesson? It is important to understand that some of these food components are used mainly for energy and some mainly to help us grow. Cluster 2 will go into more detail about what happens to these components inside your body, and Cluster 3 will go into more detail about how the body uses food for energy and growth. The last lesson in this cluster explains where food is used in our bodies. Where do you think? Food, Energy and Growth 13 Where is food used in our bodies ? Many students believe that food is used in our stomachs. They have very little notion of the cellular nature of organisms, and that nutrients from food are needed by cells. If students suggest that food is used in our stomachs, you might get them to think more deeply about this by asking: If energy is released from food, and if your muscles need energy when they work, how does the energy get to your muscles. Students answers to this question are interesting. Some might picture the human body like a giant electrical circuit, with the stomach being the battery, sending energy out to muscles over wires. The idea that this unit develops is that the “energy” goes around the body as digested food (glucose), to be released as needed for various cell activities. Food, Energy, and Growth 19.a) Students should include the following key points: Foods that help you grow must have the proper nutrients forgrowth. “Junkfoods”have too much of some nutrients that we only need in small amounts and not enough of the others. Many students associate fat and sugar with “junk food” and think that all sugar and fat is bad for you. Since each is a nutrient, your body needs it-but in smaller quantities than most people eat. You could determine which components are present in any particular food by performing the food test on the food. b) Answers vary TEACHER’S GUIDE Lesson 2 TG 13 Lesson 3 c3 WHERE THE ACTION IS THE CELLS Let’s review: 1. People need energy from food for all life activities; different components from foodareneededforgrowingwell. (How cells extract the stored energy in food (cellular respiration) and how cells and organisms grow (protein synthesis) are discussed in Cluster 3.) 1. You have learned that food does two things for people. To the best of your ability, explain what those two things are If you said that food gives people energy and helps people grow, you are on the right track. You also need to say -why people need energy and - what it is about food that helps people grow. Many students have the naive notion that food goes into their stomach, is changed in some way, and goes out through their rectum. Most students don’t know much about cells. They might know about blood cells, but only a few know that cells make up nearly every structure in our bodies, and that food needs t o travel to all cells for their activities. 0 Key Question Where do you think that food finally winds up in your body, so that it can release its energy or help you grow? If your leg muscles need energy to help you run, does your body actually take food to your legs? If your eyelid muscles need energy to wink, does your body have a way ofgetting food to your eyelids? Or does food just go to your stomach, get changed somehow, and come out the other end? Let’s begin to discuss these questions by thinking about what makes up your body. If you look through a very p o w e r microsoope at skin, what will you see? S%& Let students write their initial thoughts on this question before any class discussion, then open up discussion for brainstorming. The idea of cells is developed through this entire lesson. If you look through a magnifying glass at the skin on the back of your hand, you will see skin details-the hairs and what they come out of, the little cracks on the skin, places that might be dry and dead. 14 Michigarr Department of Education Lesson Statement: After about what cells are and where they can be found, students make a sand sculpture as an analogy to the cell structure of living things. Lesson 3 TG 14 Purpose: To help students reconstruct any prior knowledge about cells and further develop the idea that every single part of a living organism is made up of cells. Approximate Time: 1 class period. S e e Advance preparation in blue pages. Michigan Department of Education If you use I a microscope which magnifies -_1 your skin even more, you can see r new details. Your skin no longer looks flat, but bumpy. If you look through a microscope with high magnification, your akin will suddenly look like a collection of small "pebbles.” What do you think those “pebbles” are? Those " p e b b l e s are skin cells. All of your skin is made from millions of these tiny cells. Some of you may have heard about cells before. What do people in your class think they are? Why do they believe what they do? 2. a) What are the tiniest living parts of a heart? Allow students some time to discuss what they think cells are, what cells do, and where they are found in the body. Also ask them to justify their beliefs with evidence or reasoning. 2. a) Heart cells b) What are the tiniest living parts of skin? b) Skincells c) What are the tiniest living parts of blood? c) Bloodcells If you looked at muscle tissue through a microscope, you would see something very similar to what your hand looks like under the microscope-millons of tiny little cells joined together. These cells would be different from the skin cells, but it’s the same idea: Muscles and skin are made out of cells. Their tiniest living parts are cells, just as sugar granules are the tiniest parts of sugar. Are all parts of bodies made of cells? What about brains? Hearts? Stomachs? Bones? What about the fluids inside your body, like blood? How could you tell if they were? 16 Food, Energy and Growth If you have access to microscopes, you may want to let students use them to look at various objects, including any that show cell structures. (Onion skin and lettuce are good) Prepared slides are often the best for this. Allow students plenty of time to become adjusted to using the microscopes-don’t rush it. There are several inexpensive microscopes available for schools with limited resources. The video Powers of Ten is helpful for becoming oriented to the small scale of microscopic views. It’s generally available through REMC’s. Food, Energy, and Growth Almost every part of the human body is made of cells. Bones, for example, are also extrusions of calcium phosphate. TEACHER’S GUIDE Lesson 3 Xi 15 * At first, students may feel insulted by the level of this activity, but usually they will get into the sculpture part of it quickly. Be sure, however, that they realize why they are doing this--that they understand the similarity between grains of sand of their sculpture and cells of all living things. Also, help them realize that just as grains of sand come in different sizes, shapes and colors, so do cells in all living things. Heart cells are: different from skin cells, anddifferentagainfrom bloodcells,etc. Their sculpture is different from living organisms in several ways. The most important way is that the “cells” in their sculpture are not organized into tissues and organs, like the heart, the liver, bones, muscles, the brain, etc. Try This A. Take a cup full of wet sand. Mold and shape it to look like a living organism of some kind: a person, a plant, an animal. Describe in your journal how the sculpture resembles a real person, plant or animal. Think about what each grain of sand represents. Also describe how this sand model is different from a living organism. All of your body’s cells are living. They need food and oxygen just like all living things do. They get rid of waste producta, just like all living things do. They’re busy all the time, doing all different kinds of things. You’d be surprised at the different activities that go on in cells. I So now the question is, does the food you eat go to your stomach, get used somehow in your stomach, and then go straight out through the other end? Or does the food you eat perhaps just get changed somehow in your stomach, and then move to your cells, to be used in your cells? Choose one of these two possibilities that you think makes the most sense to you at this time. To make this choice, think about this: Where does your body need fuel for energy? Where does your body need “raw materials” for building new muscles, skin, blood, etc. as you grow? Well continue to talk about where food is used as the unit goes on. *** 3. By now students are beginning to construct the idea that food has to travel to every place in our bodies--to all cells-to be used for energy and growth. They might ask some questions like “Does food go to the end of your fingers?” or “Does food go into your brain?” But they also might still be thinking that food needs to travel only to those places where you are growing, or only to those places that obviously need energy, like muscles. They should develop an understanding that every cell in our bodies has a place in making our bodies work correctly, and each cell needs energy. TG 16 Does this discussion make you think of other questions about food, energy, and cells? 3. Write any other questions you would like to find answers to in your journal. Cluster 2 covers where your food goes after you chew it. You may be surprised! 16 Michigan Department of Education Michigan Department of Education Laboratory Background Information for Cluster 2 Lesson 4 THE FOOD TRIP, PART 1: THE DIGESTIVE TRACT Throughout this cluster students will be drawing their ideas of how food moves through the body, using an outline picture of the human body. It will serve two purposes: 1) The students will draw their ideas before instruction, indicating their prior knowledge and existing theories of how food moves. As the teacher observes students’ drawings, misconceptions or gaps in students’ information should become quite obvious. 2) Students will be able to add to the picture as they gain new knowledge. This will help them build the complete picture rather than having numerous isolated bits of information. p. 18 MATERIALS Outline picture of human body (in appendix) PITFALLS AND CAUTIONS 1. Help students understand that their first paragraphs are not expected to be complete or perfect. Encourage students to make corrections and add to them as they learn new information. Their final picture and paragraph should tell a much more detailed and complete story than their initial one. 2. Be sure students save their pictures. You may wish to collect them and save them for when they are needed again (at the end of Lesson 6 and 9.) Lesson 5 DIGESTING FOODS: WHERE DOES IT START? The process of digestion begins in the mouth where food is chewed and broken into small pieces. Then as it mixes with saliva, an enzyme present in the saliva reacts with starches and breaks them into simpler molecules of sugar. Students will investigate this process by testing oatmeal before they chew it and then again after it has been chewed and mixed with saliva. They may also decide to test the saliva by itself. They are able to see from the tests they perform that neither the saliva alone or the unchewed oatmeal contain sugar. Only after it has been chewed and mixed with the saliva does the oatmeal test positive for sugar. An enzyme in the saliva breaks the larger starch molecules into smaller, simpler sugar molecules. It is possible to actually taste this change. At the end of the activity, you might want to have the students chew a cracker slowly and thoroughly without swallowingit. After a minute or two, ask them if they can notice a change in the taste. It gets sweeter. Food, Energy and Growth TEACHER’S GUIDE p. 19 lab prep 7 MATERIALS 4 large test tubes (8 if also doing the starch test) 18 x 150 mm, eye droppers, clean rubber bands or paraffin (chewing on these helps generate saliva), uncooked oatmeal, Benedict’s solution, grease pencils. You may have these solutions left from previous labs. If not, see directions on page “lab prep 3,” in the blue pages prior to Cluster 1. PZTFALLS AND CAUTIONS 1. HIV concerns: You might want to do this experiment as a demonstration, to avoid possible transmission of HIV from student to student via saliva. While research has shown that transmission of HIV through saliva is very rare, at the time ofpublication new OSHA regulations were being distributed that might limit these kinds of lab activities. 2. It is very difficult to find a substance that does not have any sugar in it and will therefore give a negative sugar test before it chewed. If you want to use crackers instead of oatmeal, be sure to test them first. Oatmeal, even though dry, really tastes quite good. 3. The purpose of the warm water bath is to simulate body temperature so it only needs to be warm, not really hot. 4. Students who design their own labs will probably include a starch test as part of their plan and should proceed accordingly. However, the plan provided does not include this test but depends on knowledge from activities in the previous cluster. 5. The flow of saliva in the mouth can be increased by chewing on a clean rubber band or soft paraffin if students choose to test saliva for sugar. 6. Students may need to refer back to the food tests in Cluster 1 when planning their food tests. Lesson 6 MORE ON DIGESTING FOODS: BREAKING DOWN PROTEINS p. 22 This activity allows the students to see what happens to protein when it undergoes digestion. They will use unflavored meat tenderizer (without MSG) to digest gelatin. The meat tenderizer contains an enzyme (probably papain, obtained from papaya) that breaks protein into amino acids. Fresh pineapple contains an enzyme similar to the one in meat tenderizer called bromelian). As is true of most enzymes, it becomes inactive when heated. This happens when the pineapple is canned. Students will investigate the effect of fresh and canned pineapple on the gelatin (protein). An alternate way to do part B would be to have students prepare flavored jello with fresh and with canned pineapple. Jello prepared with a substantial amount of fresh pineapple will not set. lab prep 8 Michigan Department of Education MATERIALS 3 Petri dishes without covers; stirring rods; measuring spoons; unflavored gelatin; unseasoned meat tenderizer; fresh pineapple; crushed canned pineapple. Gelatin must be prepared ahead of time and allowed to set. Use unflavored gelatin and prepare it according to the directions on the package (1 envelope in one cup ofboiling water.) Stir until the gelatin is thoroughly dissolved. Pour into a pan so that the gelatin is about l/4" thick. Refrigerate and allow to set. Cut into 1/2” squares. The pineapple should be crushed in a food processor or blender until most of the pulp is exposed. Enzyme activity is mostly in the pulp. But you may want to try a slice of fresh pineapple directly on the gelatin, since the crushing may even destroy the enzyme. PITFALLS AND CAU’I’IONS 1. Since the enzyme activity can occur only where the gelatin is in contact with the meat tenderizer or pineapple, the gelatin should have plenty of surface area and be covered on all sides. If it is more than l/4” thick, the reaction is less obvious. Lesson 7 GETTING FOOD TO THE CELLS: MOVING IN A N D OUT OF TIGHT PLACES p. 27 In this activity, the students will investigate the process of digestion as a means for breaking down food into very small particles. These particles must be small enough to leave the intestine (through very small openings or holes in the walls) and then enter the bloodstream through similar openings or holes in these very thin walls. Students use sand and a piece of screen as a model. They should be able to see that sand particles that are small enough can get through the screen. Other, larger sand particles must be crushed or ground finer in order to get through the small openings. Similarly in digestion, food particles are broken into smaller and smaller particles in order to get out of the small intestine and into the bloodstream. Particles that do not get broken down or digested continue moving through the food tube to the large intestine and are eventually eliminated from the body as feces. Students will simulate the chewingprocess with gelatin that they break or chop physically into small pieces. They then use the digestive enzyme contained in meat tenderizer to “digest” the gelatin that has been chopped. They observe it as some of it passes through the screen and some of it remains in sufficiently large pieces that it cannot pass through the screen. Food, Energy and Growth TEACHER’S GUIDE lab prep 9 MATERIALS &PREPARATION Screen (18 or 20 mesh, 5” x 5” or large enough to fit over the beaker or dish after a depression has been made in it), 250 ml beaker or a small dish, a small container of course sand (available at hardware stores), unflavored gelatin (about 1” x 1” x l/4”), mortar and pestle or other means to crush gelatin (plastic forks work), stirring rod, meat tenderizer. Gelatin must be prepared ahead of time and allowed to set. See Materials and Preparation p. lab prep 9, Lesson 6) PITFALLS AND CAUTIONS 1. Sand should be carefully selected so that some, but not all of it goes through the screen. Aquarium gravel can be mixed with fine and course sand. 2. Students will probably suggest that in order for more of the sand to get through the screen, it needs to be ground finer or pulverized. A good way to do this would be to provide a mortar and pestle if available. Another way may be to put the sand into a piece of fine cloth and pound it with a hammer. 3. The digestion of the gelatin will begin somewhat slowly, but within a few minutes liquid will begin to drip through the screen. 4. Window screen is available from hardware stores. Look for 18 to 20 mesh (18 to 20 wires per inch.) Plastic screen prevents scratches. Lesson 8 THE FOOD TRIP, PART 2: TAKING A RIDE ON THE BLOOD BUS P- 31 The purpose of this activity is to help students connect their laboratory studies of digestive processes with the physiology of the body, through the use of a model. Though the model-building may at first seem a bit simplistic, it is an important part of the conceptualization that must take place if students are to thoroughly understand this process. MATERIALS Assemble the needed materials into a kit for each group ofstudents: Cardboard (8 l/2 x 11"), yarn of three different colors (4 feet of brown for digestive system, 6 feet of red for circulatory system, 1 foot of another color for the cells), push pins and glue, tape, highlighters of three different colors, scissors, diagrams of digestive system and food particles (in appendix). Cardboard from the back of tablets works well or you may use tagboard or cut up cardboard boxes. PITFALLS AND CAUTIONS 1. Since the pieces of digested food are very tiny, they should be pinned to the board immediately so they are not lost. 2. Do not use oil-based markers instead of highlighters since they will probably go through the paper and mark the desks. Water-based markers will work well. lab prep 10 Michigan Department of Education 3. Some fiber molecules could be added (along with the proteins, carbohydrates, and fats) to show that some of the food particles are too big to get through the openings. Students should understand from this that not everything we eat is able to be used by the cells. This unused material is eliminated from the body. Also, some of the proteins, carbohydrates, and fats are simply not digested, and also move out of the small intestine to the large intestine, then out of the body. 4. You may prefer to do this activity as a whole class activity rather than as an individual activity. Some students will probably not get as full an understanding as they would if each student (or pair of students) did it separately. 5. An alternative to using cardboard and pins is to use a flannel board with yam and pieces of flannel. Another excellent alternative, if resources are available, is a magnetic board with pieces of magnetic tape with sticky backs (available from craft stores that deal with cross-stitch.) A small piece of magnetic tape is stuck to each movable piece and it can easily be moved around the magnetic board without falling. An alternative to using yarn would be to color on the diagrams with colored markers. The effect of certain molecules not being able to pass through the boundary between the small intestine and the blood vessels is not as pronounced, though, as with yam. Lesson 9 THE DIGESTIVE AND CIRCULATORY SYSTEMS: PUTTING IT ALL TOGETHER p. 34 This activity is an assessment of how students’ ideas have changed from Lesson 4 to now. They complete their drawing of ‘The food trip” and write an explanation of what happens to food as it travels through our bodies. MATERIALS Students revise and add to the picture they began in Lesson 4. Food, Energy and Growth TEACHER’S GUIDE lab prep 11 lab prep 12 Michigan Department of Education :HOW DOES FOOD GET 0\-qg 2 A TO WHERE IT’S USED? ‘WHAT HAPPENS TO IT ALONG THE WAY? I?eople eat food because it tastes good. But you know now that you need food for two far more important reasons. First, food stores energy, which is released in your body for all of the activities you do everyday. Second, the food you eat is needed for growiug and for repairing or replacing parts of our bodies when they get damaged or wear out. Can food be used by our bodies for energy or growth exactly in the form it’s in when you eat it? Is the food you eat changed as it makes its way through your body? If food is used in your cells, are there little pieces of meat, little pieces of cookies, or little pieces of fruit that go to our cells? What happens to the fats, proteins and carbohydrates in foods? In this cluster and in Cluster 3 you will investigate, in more detail, how this happens. P Key Questions Where does your food go after you swallow it? What happens to your food as it enters your body? Food, Energy and Gmwth Food, Energy, and Growth These questions don’t need complete answers now. Students will construct answers to these questions as they work through Cluster 2. Right now, many students probably still believe that food primarily gets used in the stomach and excreted, witbout traveling to the cells. The purpose of Cluster 2 is to establish the connection between the workings of the digestive system and the circulatory system in getting energy-rich substances and molecular “building blocks” to the cells. 17 TEACHER’S GUIDE TG 17 Lesson 4 65 THE FOOD TRIP, Part 1: The digestive tract This lesson is a preassessment for Cluster 2 If students work on this activity individually, you will have a record of what they believe before in structure, which will help you understand better and respond to their questions throughout the cluster. Once you swallow, the food you eat starts on a fantastic trip down into your body. Think for a minute about eating a tuna fish sandwich. What happens to that sandwich after you swallow it? Where does the food go? How far can you trace food on its trip into your body? 1. On an outline picture of the human body (labeled “My first drawing of the food trip’), draw in any parts or organs you think your food goes through, and label them. Use lines and arrows to show where the food goes. 1. Student pictures will vary greatly in the parts they include. Some will show only the mouth, throat, and stomach. Others might show more. Don’t give them clues here about what other parts to include. They should discover these and add to the picture as you continue the cluster. Have students keep these drawings, since they will add to them, and you may ‘want an opportunity later in the cluster to talk with them about some part they included in the early drawing. 2. Write a short paragraph under the drawing to explain what you believe about the path food takes in yourbody, from where it’s eaten to where it’s used. Explain what youbelieve happens to food as it travels through your body. 3. Think of two questions of how, where, and why food is digested. Write them on the same page with your drawing and paragraph. 2. Students at this age often think of the food’s path as going straight to the stomach, then out through the excretory organs. Their ideas about what happens along the way are often vague and naive, such as “food changes to energy when it’s digested.” 4. Save your drawing to refer to later. Most of you probably included a stomach in your drawing. Most people know that food travels to the stomach. The really important question here is Does food get used for energy and for materials for new cells right in the stomach, with the waste products moving farther down and passing out of the body? Or does food go somewhere else? It is important that students explain the processes in their own words and not try to use vocabulary that may have no meaning to them. If you read some Be very thoughtful about this question. We talked a bit about cells in Cluster 1. What do cells have to do with digestion and the food trip? papers that use complex terms without explaining them, you may want to ask those students what they mean by those words. 18 Michigan Department of Education 3. Answers vary. Lesson Statement: Students show what they know about the path of food in the human body by drawing the organs involved in this process on a picture of a human torso and then writing about the process. Lesson 4 TG 18 Purpose: To explore students’ prior knowledge about what happens to food after they eat it. Approximate Time: 1 class period. Michigan Department of Education DIGESTING FOODS: Where does it start? Lesson 5 iif Many of you probably know that food is digested as it travels down into your body. But what exactly does that mean? Does it mean that food is made into smaller pieces? Does it mean that it is changed somehow? Is digestion the process of releasing energy from food? We’ll explore the process of digestion in the first part of this cluster. We’ll start in this lesson by exploring where digestion starts. Where do you think digestion starts? If you said “Digestion starts in your mouth,” is there a way to find out for sure? One way to explore what’s going on in your mouth is to chew up some food, take it out, and see if it has changed in any way. How can you tell ifit’schanged? In what ways might it change? Has it’s temperature changed? Has it’s size changed? Did it change intc a new substance? How could you tell if a new substance is produced? Remember the food tests you did for starch and sugar in Cluster l? Did you test oatmeal? What was it composed of? If oatmeal changes in your mouth into a new substance, what experiment could you do to tell? In previous food tests, students found 4 Try This An experiment should include 1) testing oatmeal for sugar-or protein or fat--before it’s chewed to show that it contains none; these tests were done in Lesson 2 2) testing oatmeal after it’s chewed to discover if it’s changed into sugar, protein or fat 3) testing saliva by itself to rule out the possibility of saliva alonecontaining sugar. Many students will not think of testing saliva. Page 21 is designed to help them figure this out. They can conduct the test on saliva after they read the top of p. 21. Talk among your group members about how to test chewed oatmeal to see if it changes in your mouth. Think through everything you might want to do. Then write a plan in your journal. Your experiment might look like this: 1) Test the oatmeal before it’s chewed, and record your results. 2) Test the oatmeal after it’s been chewed, and record your results. 3) Try to explain your results. 19 Food, Energy , and Growth Lesson Statement: Students either design an experiment or use the given instructions to e:xpIore the part of digestion that occurs in the mouth. They perform the tests for sugar and starch on oatmeal before and after it has been chewed. Purpose: To investigate both the chemical changes that occur in the mouth as food begins to uadergo the process of digestion. Approximate Time; 1 l/2 class periods. Food, Energy, and Growth TEACHER’S GUIDE that oatmeal is composed only of starch-no sugar, protein, or fat. Ll Lesson 5 TG 19 Are you thinking about testing the oatmeal (after chewing) for all of the components in food? A little thinking before the experiment might help you decide what tests to do. Remember that oatmeal is a starch. Starches and sugar are both carbohydrates. Maybe the starch in oatmeal could change. into sugar. If this is true, you’d have to do only one test-for sugar. l l (why Benedict’s solution?) test tubes test tube holder . a boiling water bath Boiling water burns badly! Benedict's solution can irritate eye8 and skin. If spilIecl, wash with plenty of water. Get help from your teacher. Try your experiment. Use the directions below if you would like to follow stepby-step instructions. Test the oatmeal before and after chewing: A. Place approximately 1 teaspoon of oatmeal--out of the box-in test tube A (or you could label this the 'before” test tube.) Using an eye dropper, add several drops of water to soften and moisten the oatmeal. B. Next, chew on approximately 1 teaspoon of oatmeal without swallowing it. After 1 to 2 minutes, place the chewedoatmeal in test tuhe B (the “after” test tube.) C. Place both test tubes in a beaker of boiling water. Wait 5 minutes. D. Add about 20 drops of Benedict’s solution to each test tube. E. Heat each of the test tubes gently for 2 to 4 minutes or until a color change is noted. F. Record your results in your journal. Did you find that the oatmeal tested “positive” for sugar after it was chewed? How can you explain this? 20 Michigan Department of Education Is chewing a part of digestion? Many biology texts include the physical/mechanical process of chewing as a part of digestion. Others disagree, arguing that digestion is purely a chemical process. We have chosen to explain digestion in this unit as only the chemical process Lesson 5 TG 20 that uses enzymes to change food into new substances. We are purposefully not including chewing as part of digestion, because it is not a chemical change. Research suggests that many chemical changes are not really understood by students, who explain them instead as some sort of physical change. So we are searching for ways not to increase this confusion. Although chewing increases the surface area of food on which enzymes can act, it does not change food into a new substance. Michigan Department of Education I.. One explanation is that the grinding of the oatmeal by your teeth produced the sugar. Do you agree? How could you test this? II. Another possible explanation is that something in your mouth chemically reacted with the oatmeal to change it into a new substance. If this is true, what could there be in your mouth that could do that? III. A third possible explanation is that the saliva in your mouth contains sugar, and it mixed in with the oatmeal as you chewed. What do you think about this? How could you test this? I. You could test this by grinding up oatmeal outside of the mouth, in a mortar and pestle, and then testing it IlI. You could test for sugar already in your mouth by testing saliva. (It tests negative for sugar.) 1. Think over the three possible explanations above. Write in your journal your explanation for why sugar is produced when oatmeal is chewed. 2. Try any tests you can think of to prove or disprove any of the three possible explanations. 3. Do you think digestion starts in the mouth? If you said yes, what evidence do you have? If you said no, why? 4. Discuss your explanation with your group partners. After your discussion, make any changes that will make your explanation better. 1. Answers will vary, but most students will probably choose one of the three possibilities stated at top of page. 2. If students test chewed oatmeal for sugar, they should also test saliva to determine if it has any sugar itself (it doesn’t.). This would allow them to decide on whether they believe the: 3rd possible explanation (III). (It is often helpful to chew on a clean rubber band or paraffm to produce saliva. Students should not test their saliva after eating.) 3. Digestion is the chemical breakdown of foods. It begins in the mouth when salivachemically reacts with starches to form sugars (simple and smaller molecules.) 4. If students chose I or III, they may change to II after testing saliva and discussing the test results with their group partners. - 21 Food, Energy and Growth Lesson 5 Food, Energy, and Growth TEACHER’S GUIDE TG21 MORE ON DIGESTING FOODS: Breaking down proteins Lesson 6 @ Think back to your food tests. What kinds of foods have protein in them? As these foods travel down into the stomach, they are bathed in digestive chemicals called enzymes. These are new enzymes, different from the ones in saliva. They help to break down the fats and proteins, as well as the carbohydrates. Scientists have extracted these chemical enzymes from human bodies. They know what they’re like. You can actually see what digestion of protein is like, using enzymes similar to ones in your stomach. ii) Try This For a protein, use gelatin, the same protein you used in the food tests in Cluster 1. Gelatin is a protein that actually helps make up the tendons and ligaments of animals (the tissues that connect bones and muscles.) A. Obtain a container of unseasoned meat tenderizer. Bead the ingredients listed on the container. Record these ingredients in your journal. B. Use two petri dishes (covers not needed). Use a grease pencil to number them 1 and 2. C. Place one square (about l/2” x l/2”) of set, unflavored gelatin d in each petri dish. Observe the consistency of the gelatin by gently poking at it with a stirring rod. Record your observations. 22 Lesson 6 TG 22 Michigan Dqartment of Education Purpose: To use the digestion of protein in gelatin as a basis for understanding how protein and fat are digested in the human body. Approximate Time: 2 class periods. Michigan Department of Education Step E requires students to check on D. Use one square of gelatin as the control (what does that mean?) Then sprinkle both sides of the other of gelatin with one-quarter teaspoon of meat tenderizer. E. After 2 minutes, poke the gelatin gently with a stirringrod to check its consistency. You may notice that water also comes out of the gelatin, but in this activity, you are mainly concerned with the consistency of the gelatin. Record your observations. Repeat this test at 5-minute intervals for at least four observations, more if time permits. Keep recording. 1. At the end of this experiment, how is the control gelatin different from the gelatin treated with meat tenderizer? 2. Draw a conclusion from your observations: In which case was the gelatin actually broken down or “digested”-the control or the one treated with meat tenderizer? 3. Look at the label on the meat tenderizer and decide which ingredient is responsible for this reaction. The chemical substance which actually breaks up the gelatin is-can you guess?-an enzyme. the consistency of their gelatin every 5 minutes over a period of 20 minutes or so. During this time, you may want to have them write in their journals first a prediction about what they might see, and then their own speculation about what is happening. That is, their “observations” might include more than just a note about the appearance of the gelatin-they may also include some analysis of what might be happening. They should especially come to see the difference between any water that leaves the gelatin. and the product o f the chemical reaction, which might look “watery.” You may want to ask students to clarify their notes if they suggest that the gelatin is tuming watery. Do they mean that it’s turning into water, or simply changing to the consistency of water? 1. The control stayed very hard and firm while the one with the meat tenderizer got very soft and liquid-like. 2. The treated one. 3. Usually papain, a derivative of the papaya plant. 4. Now think about real meat and how meat tenderizer works. a) Meat tenderizer reacts with which nutrient in meat? b) What does it do to that component? c) How do you think meat tenderizer works? 5. a) Explain, in your own words, using a couple of sentences, what happens to proteins in your body after you eat them. Talk about where the foods containing protein travel, what happens to them along the way, and what chemical substance is necessary for this to happen. b) Add to your drawing and explanation from Lesson 4, or start a new drawing, to show what you’re learning that’s new. Save your drawings for later use. 4. a) Protein. b) It helps digest the protein and make it soft and not so tough. c) It is an enzyme that chemically changes the protein so it can be used by cells. 5. The key points are: the protein enters your mouth (where itiscrushedandgroundas itischewed). it goes through the esophagus to the stomach where the protein is mixed with enzymes that begin to chemically change it into simpler substances. it then leaves the stomach and goes into the small intestine where it is mixed with more enzymes that continue the process of chemically changing it into l l 6. Speculate: Where in your body do you think the chemical substancethe enzyme-that breaks down protein could come from? 23 Food,, Energy and Growth 6. Students’ answers vary. It may be interesting to ask them why they think what they do. It comes from the walls of the stomach and small intestine and from the pancreas. Food, Energy, and Growth TEACHER’S GUIDE l I Lesson II TG 23 The fresh pineapple contains an enzyme that can break down the gelatin protein because the canning process heats the pineapple, destroying the enzyme. The canned pineapple has no effect on the gelatin. In step I: While students are waiting to check the gelatin at 5-minuteintervals, you might ask them to consider what other varialbles are involved in determining the speed of this gelatin breakdown (surface area, temperature, etc. are variables that they may come up with.) Let them ponder this for awhile, and perhaps design au experiment to test out their ideas. If someone came up with the idea of temperature, they could develop a hypothesis to test, such as ‘warmer gelatin will break down more quickly.’ * More fun with enzymes - try a different source: F. This time, use three pieces of gelatin to test two different substances that may or may not contain enzymes that can break down protein. The two substances are 1) crushed, canned pineapple, and 2) crushed, fresh pineapple. Use three petri dishes without covers, numbered 1 through 3. G. Place one square (about l/2” x 1/2”) of set, unflavored gelatin into each petri dish. Observe the firmness and texture of the gelatin by gently poking at it with a stirring rod. Record your observations. H. Treat each piece of gelatin as follows: #l: Control #2: Place some crushed fresh pineapple directly on top of the gelatin. #3: Place some crushed canned pineapple directly on top of the gelatin. I. 7. Usually the gelatin treated with canned pineapple got a little soft compared to the control but not nearly as soft as the fresh pineapple. Students may say that both gelatins treated with pineapple were the same because they think that is what ought to happen rather than actually observing what actually happens. Try to encourage them to really use their powers of observation. 8. The fresh pineapple must have an enzyme in ithat can break down protein. 9. The canning process must have destroyed the enzyme. Many enzymes arc quite sensitive to heat. After 2 minutes, poke the gelatin pieces gently with a stirring rod to check their consistencies. Record your observations Repeat this test at fiveminute intervals for at least four observations, more if time permits. Use your journal to keep track of your observations. Write down any questions that come to your mind. 7. So what do you conclude? Does either type of pineapple contain a good enzyme for digesting protein? 8. Here’s an interesting question: My dad says you can’t use fresh pineapple if you’re making jello with fruit in it, only canned. Why? 9. Speculate: If fresh pineapple originally had the chemical ability to break down proteins, what do you think happened to destroy the chemical activity of the enzyme in canned pineapple? What have we figured out so far about digestion? How close are we to constructing a good explanation of what goes on with food in our bodies? 24 Michigan Department of Education Lesson 6 TG 24 Michigan Department of Education &3 A scientific explanation of digestion So far in this cluster, you have explored the digestion of two substances, starch (one type of carbohydrate) and protein. During the digestive process, starches (and other carbohydrates) are chemically broken down into simpler particlesmolecules-called glucose (one type of sugar.) Glucose is a very small, simple sugar molecule. You may remember that it is the same sugar that plants form during the process of photosynthesis. All the starch and other carbohydrates that you eat in your food (including table sugar) are chemically broken down into glucose. This breakdown begins in your mouth and continues in your small intestine. Chemicals, called enzymes, which cause this breakdown, are in saliva and in digestive juices found in your small intestine. Protein in your food does not begin to be digested until it reaches the stomach. There, the enzymes in the stomach begin reacting with the protein to break it into simpler molecules called amino acids. Only part of the protein is digested in the stomach. Most of it passes, undigested, into the small intestine where more enzymes are produced for breaking down rest of the protein into amino acids. C a r b o h y d r a t e s b r e a k glucose (simple sugar) break down into l amino acids Proteins Glucose from carbohydrates is used mostly for energy. Amino acids are the building materials used for making new cell parts and repairing old ones. Amino acids make new proteins that become parts of new cells when your body is growing. Skin, muscle, blood, and hair, and even enzymes all contain proteins. 25 Food, Energy and Gmwth The digestive tract is actually over 10 meters (approx. 30 feet) long. Over half of it is the small intestine. The esophagus (throat) and small intestine help move the food along by contractions of the muscles in their walls. Muscle contractions-churning-also help combine the food thoroughly with digestive enzymes. Food remains in the stomach for 2 to 3 hours, and in the small intestine for 8 to 12 hours. U Food, Energy, and Growth TEACHER’S GUIDE What about fats? We haven’t done an activity that shows how fats are digested, but it’s the same idea. In the small intestine, more digestive enzymes break fat into simpler “building block” molecules called fatty acids. Fattty acids can bechanged into glucose if needed for energy, or into amino acids for building new proteins. Fattty acids arc also important for several uses in the body, including making cell membranes, protecting nerve cells in the brain, making hormones. etc. break down into fats - fatty acids These fatty acids get rebuilt in the cells into new fats.. Some of these new fats store energy until the cells need it (that’s what body fat is, a place to store food for when you need energy), and some fatty acids are used in making amino acids-for making proteins that help make new cells and repair damaged cells. 10. Important points to show on diagram include: starches are partially digested in the mouth but most of the digestion 10. Using the second drawing that you started earlier in this lesson, check it to make sure that it includes a mouth, stomach and small intestine. Use arrows and labels to show on the diagram where fate, proteins, and carbohydrates begin the processes of digestion. (Save the drawing.) l takes place in the small intestine; they become simple sugars called glucose. proteins are partially digested in l the stomach but most of the digestion takes place in the small intestine; they become amino acids. fats arc digested in the small intestine; they become fatty acids. l You may want to pose this last question to your students, either at the end of this lesson or the beginning of the next, to help them uncover any prior knowledge they may have about the circulatory system. Check their responses t o see if they talk about “cells.” Where are we now on the food trip? We’re somewhere in the small intestine. The food has been chemically changed into new substances-amino acids, glucose, and fatty acids. Has the food finished its job at this point? Or is there still more to this story of the food trip? 26 TG 26 Michigan Department of Education Michigan Department of Education - GETTNG FOOD TO THE CELLS: Moving through tight places Lesson 7 You now know that after we eat our food, it is chemically broken down (digested) into new substances in our mouth, stomach and small intestine. These new substancesglucose, aminoacids, and fatty acids-are used by the cells as fuel for energy and as building blocks for making new cdl parts. In this and the next lesson, we will explore two models that show how the food gets out of the small intestine and begins its trip around our body to all the cells. - Key ‘1 Q uestions You could use the first transparency of “The Human Body” set (in the appendix&showing only the digestive system-to pose the first “key question.” How do you think the digested food gets to all of the cells of your body? How does it get out of the small intestine? If you answered y in blood” for the first question, you’re right! Blood vessels are the delivery system of the body. Think of blood as something like a city bus, following its route, picking up “passengers” and dropping them off when necessary. Bllood is constantly moving past the small intestine, picking up digested food and carrying it everywhere around the body to the cells, dropping a little off here and there as needed. Most students’ knowledge of how bodies use food ends after digestion. They rarely think of it as having to reach all of the cells before it can be used by our body. Not everything that enters your mouth can get a ride on the blood bus, though. You’ll figure out why as you try these activities. l You will need: l 8 piece of screen (5’” x 5” or large 9 Try This l A. Place the screen over the beaker and shape it to make a depression in the middle. l l enough to fit over a beaker or small fish) a 250 ml beaker or a small dish a small container of coarse sand more unflavored gelatin (a piece about 1” x 1” x l/4”) Mixing aquarium gravel with fine and course sand works well. B. Pour the sand into the depression in the screen. Use a spatula or your finger to stir it around in the screen. Does all of the sand go through the screen? Record your observations in your journal. Food, Energy and Growth 27 Lesson Statement: Students use window screen with l)sand and gravel and 2)gelatin and enzymes and decide which particles pass through the screen. They devise ways to make more particles go through it. Finally they relate these ideas to the passage of food from the small intestine to the blood stream. Purpose: To use several modeIs to help understand how digested food particles pass through the wall of the small intestine and into the blood stream. Approximate Time: 2 class periods Food, Energy, and Growth TEACHER’S GUIDE cl Lesson 7 TG ;!7 1. The size. 1. What property of the sand particles determined whether they passed 2. Crush what didn’t go through the first time and then try again. Unfortunately, this is where this analogy breaks down. Crushing is like chewing. It works for getting gravel through screen, but it’s not what happens in the digestive system, and crushing gelatin alone will not really allow more to pass through the screen (some will if you push really hard.) The gelatin, made of very long molecular chains. is still composed of long chains even if it is crushed or brokenintosmallpieces. Theenzyme actually breaks the long molecular chains into shorter chains, just as enzymes in the stomach and small intestine do to proteins.. through the screen or not? 2. How could you make more of the sand particles pass through the screen? If possible, try out your suggested method. C. Use the same piece of screen you used with the sand. Get a piece of “undigested” protein (gelatin). D. Crush or chop the gelatin into small pieces with a mortar and pestle or by some other means you or your teacher devise. E. Place the screen over the beaker or dish as in part A above and place the gelatin into the depression on the screen. Will the gelatin go through the screen? Record your observations on your data sheet . SF 3. How might you be able to get the gelatin to go through the screen? 3. Allow students to speculate about this. If any come up with good suggestions, perhaps you might want to have the class try them. The approach used in F-H is to “digest” the gelatin using meat tenderizer. Ifyoucan’t think of a way to get the gelatin to go through the screen, here’s a hint: What happens to it when it’s ‘digested”? Could you “digest” it? F. Make a small depression in the middle of the gelatin in the screen and place about l/4 teaspoon of meat tenderizer on the gelatin in this depression. Use a spatula to stir the meat tenderizer into the gelatin. Be sure the gelatin and meat tenderizer are well mixed. Observe carefully for a few minutes. G. Stir occasionally. After about 5 to 8 minutes, add a little more meat tenderizer. Mix well. H. Observe for about 5 t.c 10 minutes more. Record your observations. 28 Michigan Department of Education Lesson 7 TG 28 Michigan Department of Education - 3. a) How is crushing or chopping the gelatin similar to what happens to the food we eat? b) If physically crushed gelatin can’t get through the screen, what else could be done to it to get it through? 4. You probably noticed that not all the gelatin passes through the screen. Why do you think that is? You already know that enzymes in your small intestine chemically change proteins into smaller, simpler “building block” molecules-just like meat tenderizer changes gelatin into different, smaller pieces. The gelatin may not seem to have changed into a new substance, but it has. The meat tenderizer chemically changed the gelatin into different molecules, smaller than the original gelatin protein molecules. As a new substance, it could fit through the screen. Here’s what happens after food is chemically changed into different, simpler molecules: The new molecules pass through very small openings in the wall of the small intestine and enter the bloodstream They’ve made it onto the “blood bus”! I 5. a) If the gelatin in our experiment represented the food you eat, what did the meat tenderizer represent? 3. a) It is similar to breaking food by chewing and churning in the stomach. b) The food needs to be chemically broken down by an enzyme. 4. The particles that have not been “digested” (broken down) are too big to get through the holes in the screen. Students may refer to the substance as being too thick or say that it didn’t turn into a liquid. If they say this, they are probably not thinking of the substance as made of tiny molecules. Remind them that even liquids are made up of molecules. This idea of food being composed of molecules is essential to students understanding how digested food passes through the intestinal wall. 5. a) Enzymes. b) The walls of the intestine. b) What did the screen represent? 6. Write a few sentences about what the wall of the small intestine might be like so the digested food can pass through it and into the bloodstream. 6. Following the sand/screen analogy, the walls of the small intestine might have little openings or holes in it that allow the simpler, digested food particles to move through, big enough to let digested food out, but not big enough to let any undigested food out. See comment below. 29 Food, Energy and Gmwth Food movement from the small intestine into the blood stream: Themolecular-level picture we’re developing of food movement across the small intestine wall is simplified for the purposes of teaching at this grade level. Actually, there are several mechanisms at work here: Small molecules can pass through the small intestine wall and dissolve into the blood stream, but they have to be soluble to do this. Fats are not soluble, but fatty acids are. Also, there are molecular “carriers” that help transport molecules of digested food across this interface. The central idea for this unit is that the process of digestion is a chemical one, resulting in simpler, new “building block” molecules and glucose. It is these new, simpler molecules that pass into the blood, to be transported to cells. Food, Energy, and Growth TEACHER’S GUIDE i’ Lesson 7 TG 29 Moving digested food to the cells After your food has been broken down into its simplest form, it moves out of the One reason that fats don’t go into the blood stream but fatty acids do is that fats are not soluble, but fatty acids are. digestive tract into the bloodstream through millions oftinyfinger-like projections in the wall of the small intestine (called villi.) The food actually dissolves in the blood as individual molecules (just like sugar dissolves in hot tea or coffee.) Look back at your paragraph in #7 and add to it-if you left out something. The pumping action of the heart and other body muscles forces the digested food through millions of blood vessels to cells all over the body, where the materials from food are used. You might want to ask students to speculate and debate now on what the oxygen is for. Many will simply say that you need it to live, or that without it you’ll die from asphyxia or by suffocating. Neither one of these answers really tells how it’s used in our bodies. But don’t feel like you have to explain this now. Thi s question is only setting the stage for a discussion of cellular respiration in Cluster 3. But isn’t there something else that moves around the body in the blood? Yes! blood also carries oxygen from the lungs to all cells. What’s the You11 look carefully at what the cells do with food and oxygen in Cluster 3. *** Is there anything in food that isn’t used by the cells? Yes! In the same way that not all of the gelatin and not all of the sand gets through the screen, not all of the stuff that goes into your mouth gets through the walls of the small intestine. Some of the food you eat cannot be broken down, and remains in the small intestine. It moves into the large intestine and then out of the body as feces. This is what feces mostly is-undigested or undigestable food. How do you think the weight of your feces compares to the weight of the food you eat on a daily basis? This weight idea will come back again in Cluster 3! 30 r-i Lesson I TG 30 ’ Michigan Department of Education Urine, perspiration, and water in the body: Some students may ask about urine at this point. Urine is the body’s way of getting rid of soluble wastes created in several places. Sometimes urine is also considered a way of getting rid of water-produced by cells during cellular respiration (discussed in Cluster 3, Lesson 11.) This is not really the case, since all terrestrial animals constantly need to drink water. Water produced in cellular respiration basically adds to what’s already in the body. Water in the form of perspiration is also used as a cooling mechanism, by carrying off excess body heat when perspiration evaporates from the skin. Michigan Department of Education THE FOOD TRIP, PART2: Taking a ride on the blood bus Lesson 8 .!S In the activity you just completed, you saw that food is broken into simpler pieces, first in your mouth, and then in your stomach and small intestine. You will now try to further visualize how this process takes place in your body by building a model that traces the path of food from the small intestine to the various cells of the body. * Try This Get the kit of materials you’ll need for this activity. A. Tape or glue the drawingofthe digestive system to your piece of cardboard. B. Use a red marker to color the blood vessels (dashed lines) red. Use the red yarn to outline the walls of the blood vessels. The walls of the blood vessels are very smooth but may have many branches. C. Similarly, use a dark piece of yarn (not red) to outline the walls of the small intestine. The small intestinal wall has very wavy lines, much like corrugated paper. Pin or glue the yam in place. This cross-sectional picture of the small intestine shows just a small portion of an organ that is many feet long. For a good view of the digestive system, including the small intestine, use the 3-2-l Classroom Contact video on the digestive system, available from GPN, P.O. Box 80669, Lincoln, Nebraska, 68501, 800-228-4630. At first students may think of this activity as too simple, but they usually get quite involved in it as they begin to see how digestion really works. This activity seems to help students conceptualize and remember this process of breaking down foods into simpler molecules which can then pass out of the digestive system and into the circulatory system, to travel to the cells. D. Use the third and fourth color of yam to outline the cell membrane of one of the cells shown on the diagram. E . Locate and label each of the following parts: intestine wall, intestine interior, blood vessel wall, interior of blood vessel, and cell. F. Now find the pictures of food particles labeled carbohydrate, fat and protein. Use highlighters to color each of these a different color. Then cut them out and place them inside the intestinal cavity. Use pins to hold them in place. 31 Food, Energy and Growth Lesson statement: Students make a model of the small intestine, blood vessels and cells, and use pictures of food particles to simulate digestion. They actually move these particles from the small intestine to the blood vessels to the cells to simulate the transport of digested food. Purpose: To continue to follow the path of digested food as it is transported~fiom the small intestine to all the cells of the body Approximate Time: 2 class periods Food, Energy, and Growth Although much more expensive, there are 3-dimensional fabric paints available in craft and fabric stores that also work very well for this activity, and are faster and easier to use than yarn. TEACHER’S GUIDE Lesson 8 TG31 What is missing in your picture that will enable food to get out of the small intestine and into the blood stream? G. Make several openings in the intestinal wall by cutting away small pieces of yam (no more than I/4 inch). H. Similarly, make several small openings in the walls of the blood vessels. I. Where else do you need to make openings for the food to be able to finish its trip to the cell? Make these openings into the cells by cutting away small pieces of yarn through both membranes of the cells. Use the free ends of the yam to connect the inner and outer membranes together. J. Now the food can make its trip from the small intestine to the cell. Or can it? What did we forget? The food particles cannot get out through the openings unless they are broken down into smaller pieces. Cut each of the food particles, the carbohydrate, the fat and the protein on the lines. The colors will help you remember what kind of food particle each is. You may also wish to put a small “c" on each part of the carbohydrate, a small on each part of the fat and a small "p” on each part of the protein. - As students near the end of this activity, you may want to go around the room with a tape recorder and ask each student one or two questions. Later you could play back the best responses as a “radio broadcast.” Students usually like to listen to themselves on the tape, and usually take time to prepare good answers when they know they are being taped. protein K Now the food particles are ready to make their trip to the cells! Move the particles through the openings from the small intestine, to the blood stream and finally to the cells. Be sure that if you move them, they fit through the openings. L. When digested food arrives at the cells, they are ready to build new materials! (Save this model... there’s more on building new materials in Cluster 3.) 32 TG 32 molecule Michigan Department of Education Michigan Department of Education 1. Proteins change into amino acids, carbohydrates into glucose, and fats into fatty acids. Lets review what we’ve talked about so far: (I 1. Create a table in your journal that tells what substance each component of the food you eat changes into when it is digested. 2. What has to happen to food so that it can make the trip out of the small intestine and into the cells? 3. a) Was all of the food able to get out of the small intestine? Why or why not? b) What happens to the particles that don’t get out.? 4. Speculate: Why must new materials be assembled inside of the cells rather than being assembled and then transported? 5. a) The picture you have assembled shows only one specific cell of the organism. How many other kinds of cells can you imagine there must be in your body? b)) Name at least ten kinds of cells that need to get food. Brick by Brick: Digestion is like taking a building apart, brick by brick, so you can use the bricks to build (and power) a new building. During the process of digestion, the large molecules of the food we eat, like the building, are torn down and chemically changed into simpler molecule-the bricks. These bricks are then carried to another location, where they are used to build a different building. The bloodstream (the bus) is what carries the simpler molecules to all the cells of your body. The cells then use the “building block” molecules to make the exact proteins or fats they need to grow, to repair damaged parts, or to store energy for l.ater use. And they use the glucose molecules for the fuel needed by the cel1 for powering everything that cells do. Exactly what goes on in cells with the digested food-how cells extract the energy stored in glucose, and how they use amino acids to grow and repair themselvesis discussed in Cluster 3! 33 Food, Energy and Growth What’s feces? Indigestible food (like fiber), bacteria, mucus, dead cells, and food that just didn’t get digested: and 75% water. It’s the bacteria that produce the odor; as they feed on leftover and indigestible food, they produce gas. Some foods (notably beans and cabbage) are for a 1,arge part not digested, leaving lots for bacteria to eat, and producing lots of gas. Food, Energy, and Growth TEACHER’S GUIDE 2. It has to be chemically changed (digested) into new molecules that can pass through the small intestine wall. 3. a) No, some of the food molecules were too big to get through theopenings, like the fiber molecules. If students say “there weren’t enough enzymes,” make sure they know what the function of the enzymes is-to break down the parts of the food that are digestible-and that they aren’t just parroting back a key word without understanding what enzymes do. b) They move from the small intestine to the large intestine and out of the body as feces. 4. We begin to answer this question on the bottom of this page (“Brick by Brick”); a more-complete answer is developed in Cluster 3. It is interesting to listen to students’ speculations, though, and you should encourage this. We are referring to amino acids as “building blocks” because they are reassembled into different proteins in the cells, depending on the individual cell’s need. Each cell is responsible for synthesizing its own proteins (following directions in its DNA). The purpose (function) of digestion, then, is to take apart the food we eat, (which has been built up in other organisms into their “body parts”) into the amino acids, fatty acids, and glucose we need for making new body parts and storing and releasing energy. 5. a) Answers will vary. b) Additional cells mentioned might include skin, blood (redandwhite), brain, nerve, liver, muscle, egg, sperm, etc. Lesson 8 TG 33 Key concepts that should be included are: the digestive system includes the mouth, esophagus, stomach, and small intestine. l l digestion begins in the mouth. the enzymes in saliva change some starch into sugar. THE DIGESTIVE AND CIRCULATORY SYSTEMS: Putting it all together Lesson 9 .: 63 In the first lesson of this cluster, you explored your beginning ideas about the path that food follows in your body and what happens to it along the way. In the lessons that followed, you experimented with chemically changing food, just as it’s changed in the digestive system. You also built models of how food moves from the digestive system, through the circulatory system, to the cells, where it’s used. l l enzymes in the stomach begin to break down proteins into amino acids. enzymes in the small intestine continue to break down starch and l You might have discovered that your ideas about what happens to food changed as you worked through this cluster. Now would be a good time to finish your second drawing of the human body (from Lesson 6). This will be a good way of organizing all you know about where food goes after you eat it, and what happens to it to prepare for its arrival in the cells. protein while other enzymes in the small intestine breakdown fats into fatty acids. A. Check your drawing to make sure that it includes the major parts of the digestive system. Label each part with its name. glucose, fatty acids and amino acids are small enough to get out of the small intestine, into and out of the circulatory system (which carries it to cells) and finally into each and every cell. B. Add to your drawing the path that digested food takes to get to a cell in a leg muscle and maybe a cell in your brain. Label this “path.” all cells use digested food for energy and growth. D. Then write a short essay. Pretend that you’re a piece of food-pick out one of your favorites-and write a story about what happens to you after you’re eaten. l l undigested food passes from the small intestine to the large intestine and then out of they body as feces. C. Think about how a heart would fit into your drawing, to show how blood is pumped around the body. Add the heart and attach it to the blood vessels. l You might write a list of words on the board that students should use in their story, such as: digestive system, circulatory system, digest, mouth, small intestine, enzyme, stomach, aminoacid, cells, blood vessels, glucose, fatty acids. You might have students participate in formulating the list. E. How did your ideas about what happens to food inside your body change as you worked through this cluster? F. What questions do you have at this point about how our bodies use food? Now get ready to shrink yourself down to the size of a cell and think about what goes on in every living part of your body!l On to Cluster 3 ! 34 cl Llesson 9 TG 34 Michigan Department of Education Lesson Statemeat: Students complete the picture they made at the beginning of the cluster and write a story about the food trip as a way of solidfyng what they learned in this cluster, Purpose: To pause and think and write about what has been learned about the food trip and to see what questions remain. Approximate Time: 1 class period. Michigan Department of Education Laboratory Background Information for Cluster 3 Lesson 10 Breathing and Exercise p. 40 In this activity, students first determine that they exhale carbon dioxide, by blowinginto a solution ofbromthymol blue, and then measure their breathing rate, pulse rate, and “carbon dioxide” rate before and after exercise. They discover that after exercise they are breathing faster, their pulse rate is faster, and they are exhaling more carbon dioxide. These measurements provide evidence about what is happening when the body uses food for energy: specifically, that more oxygen is required, and more carbon dioxide produced. This evidence sets the stage for a molecular explanation ofcellular respiration in Lesson 11. MATERIALS & ADVANCE PREPARATION Stopwatch or clock with a second hand, alka seltzer tablets, one 150 ml Erlenmeyer flasks fitted with a l-hole rubber stopper through which a short piece of glass tubing attached to a piece of rubber tubing has been inserted (see the illustration in the lesson), one 150 ml beaker, bromthymol blue solution, straws, 50 ml graduated cylinder. The glass tubing should be inserted just to the bottom of the rubber stopper. The rubber tubing must be long enough to be submerged into the bromthymol blue in the beaker. Bromthymol blue solution must be made up in advance and tested for how fast it reacts. It will be used for several activities so you will want to prepare enough for these activities also. BROMTHYMOL BLUE SOLUTION (BTB) Bromthymol blue solution may be purchased already prepared from most chemical supply companies or you may prepare your own as follows. Prepare a 0.145 solution by dissolving 0.5 grams ofbromthymol blue in 500 ml of water. To thiis add ammonium hydroxide (NH,OHl or sodium hydroxide (NaOHl, drop by drop, until the solution is a deep blue. In either case, test the solution to determine how much time is required to change the color from deep blue to yellow by placing about 50 ml of the solution into a clean beaker. Blow into it through a straw noting the time required for the color to change from blue to yellow. If less than about 20 seconds is required, add 2 or 3 drops of the hydroxide solution to it and re-test. If more than about 40 seconds is required, dilute the solution with about 25 ml of water and retest. Continue adjusting until the time required to change the color is between 20 and 40 seconds. PITFALLS AND CAUTIONS 1. Make sure that each student uses her or his own straw for blowing into the BTB. Sharing straws is not an acceptable health and safety practice in labs. 2. When testing the alka-seltzer, if the glass tubing extends too far into the flask, the fizzing and bubbling alka-seltzer will get into the tube and carry over into the bromthymol blue. This should be avoided, since the test should be only for the carbon dioxide given off. 3. “Carbon dioxide rate” is not as much a rate as it is the time it takes to change BTB from blue to yellow, whichgoesdown after exercise, not up, like breathing rate and pulse rate. It might be less confusing to talk about a faster or slower rate (e.g. 20 seconds after exercise is faster than 40 seconds before exercise.) Food, E n e r g y and Growth TEACHERS GUIDE lab prep 13 4. For accurately determining“ carbon dioxide rate”, the amount ofbromthymol blue solution must be exactly the same for the before- and a&r-exercise tests. More or less solution would require more or less carbon dioxide to make it change. Use a 50 ml graduated cylinder to measure exactly 50 ml of BTB. Also, make sure that students exhale only until the solution has turned completely yellow. The second solution should be the same color as the first in order for data to be comparable. 5. Students should make all measurements, breathingrate, pulse and carbon dioxide measurement as quickly as possible after finishing exercising. Since the increased need for oxygen drops off rapidly,so do all of these measurements. 11 HOW DOES YOUR BODY ACTUALLY GET ENERGY OUT OF FOOD? Lesson p. 46 In Lesson 10, students discover that their bodies need oxygen (with food) for energy, and that carbon dioxide is given off in the process. In this lesson, they compare the evidence from Lesson 10 with the actual burning of food (butter). The burning requires oxygen, and produces carbon dioxide,releasing heat and light energy. MATERIALS AND ADVANCE PREPARATION Butter, cotton string (cut to l”), Petri dish, 250 ml beaker, matches, BTB solution. See p. “lab prep 12” for instructions for preparing BTB. PITFALLS AND CAUTIONS 1. Use real butter or you may have difficulty getting the candle to bum. 2. You can bum a peanut orwalnut, butitmay behardertotestforC0,. Also, the butter allows students to think about differences between melting and burning, physical and chemical changes. 3. The butter candle usually goes out rather quickly under the beaker, and the water level rises. This is because, molecule for molecule, there is less carbon dioxide produced than oxygen used, reducing the pressure inside the beaker. Lesson 12 GROWING p. 52 Students now complete the picture of how food is used in their bodies by using their models from Lesson 8 to simulate the formation (synthesis) of new proteins from the amino acids in the food they digest. MATERIALS Models of The Food Trip that students made in Lesson 8; diagrams of food particles (in appendix); scissors; pins Lesson 13 WEIGHT GAIN AND WEIGHT LOSS P. 56 Students consider the eating and exercise activities of two hypothetical teenagers, and the activities’ effects on weight gain and weight loss. They prepare a “balance sheet” of what goes into a person’s body and what comes out. MATERIALS A copy of the completed balance sheet is included in the appendix. lab prep 14 Michigan Department of Education HOW AND WHERE IS FOOD USED IN HUMAN BODIES? a*:@@ va Have you ever had the experience of waking up late and rushing off to school hungry? Or have you been involved in some activity and had to postpone dinner for several hours? Can you remember how you felt? You probably had that hungryfeelinginyour stomach, but wasyourbodytiredtoo-didyoufeellikeyou didn’t have very much energy? In this cluster, we will take an imaginary trip down into the cells to see how they actually use food to supply the energy you need, and how cells actually use the building blocks of food to help you grow and repair damaged body parts. In Cluster 3, you will try to come up with answers to two very important questions: 0 Key b The key questions are the objectives for this cluster. Students should be able to answer them by the end of the cluster. How do we get energy out of food? I Questions Why do you have to eat well in order to grow? Take a few minutes to write down your ideas about each ofthesequestions. Also, write any additional questions that might come to your mind as you think about them. / I I.\ P I I SOME OF THE OF A(JTIVITIES THAT YOU PERFORM EVERYDAY: l l l l hIlLLIONS I I moving your legs when you run moving the muscles of your face and vocal cords when you talk or laugh causing electrical signals to move through your nerves when you touch something hot making new skin to cover over a cut As you do more of this cluster, your answers to these questions will probably become more detailed and more in-depth. They might even change as you think about how our bodies really use food. Food, Energy, and Growth Food, Energy, and Growth 35 TEACHER’S GUIDE TG 35 BREATHmG AND EXERCISE How can we figure energy? Teachers should encourage students to speculate on these key questions, but not answer them completely now. The answers will be constructed by students as they work through this cluster. Most students know that we breathe in oxygen and breathe out carbon dioxide, but rarely do they relate the need for oxygen with energy production. They often don’t have any idea about what happens inside the body to oxygen, or where exhaled carbon dioxide comes from. Some have the naive belief that the oxygen just changes into carbon dioxide in the lungs-in which case they probably don’t have a good understanding of chemical changes. Lesson 10 f# out what’s going on inside your body when you use food for We can get evidence about what’s going on inside your body when you use food, by thinking about what happens to your body when you speed up your activitiessuch as when you run or play basketball. This is a time when you really need energy--so you must be using food quickly. What happens to your body when you’re exercising? One thing that happens to your body is that you breathe faster. Why is that? Does your body need more oxygen? For that matter, why do you breathe at all? f does your body do with the oxygen you breathe I What in? Key Questions Why do you breathe faster when you exercise? What comes out of your body when you exhale? And what does breathing have to do with food? We’ll be working on answers to these questions in this lesson and Lesson 11. eTry This In this activity, we will gather some evidence about what’s going on in your body when you use food. Have students read through the entire e x p e r i m e n t b e f o r e conducting it, creating a chart for data collection that has spaces for breathing rate, pulse rate, and “carbon dioxide rate” both before and after exercise. El Michigan Department of Education Lesson 10 TG 36 Michigan Department of Education Part 1. Check and record your breathing rate and pulse rate A. You need to have a clock or watch with a second hand available where you can watch the time. Count the number ofbreaths you take in 60 seconds-your normal breathing rate per minute. Record this in your journal. B. Similarly, count your pulse for 60 seconds- your normal pulse rate per minute. Record this journal. Part 2. Test your breath for carbon dioxide and record your “carbon dioxide raw Read these directions completely before beginning. C. Fill a beaker about 1/3 full with BTB solution. Use a straw to blow into the beaker until the color no longer changes. Record all the color changes you observe. “Carbon dioxide rate” is in quotes to indicate that it is not really a rate, but simply the amount of time it takes to turn BTB yellow. Shorter times correspond to actual higher rates of production of CO, in the body. What’s this color change all about? BTB is an “indicator solution” that changes color when a certain gas is bubbled through it. Do you know which gas in your breath makes BTB change color? For a hint, do the following: D. Rinse the beaker and fill it again about 1/3 full with BTB. Optional E. Fill a 150 ml flask with water to about an inch below the end of the glass tube. Have the l topper, glass tubing and hose ready to put into this flask. BTB t ALKA Seltzer F. Now work quickly. Add one alka-seltzer tablet to the water, put the stopper tightly in place, and submerge the hose into the beaker. Observe the BTB solution and record your observations. Do you know what gas is formed by the alka-seltzer when it is dissolved in water? It’s the same gas that’s used in soda pop to make it carbonated-carbon dioxide. That’s the gas in your breath that you measure with BTB. Food, Energy, and G r o w t h a7 Lesson 10 Food, Energy, and Growth TEACHER’S GUIDE TG 37 G. Now, determine the amount of carbon dioxide in your breath by seeing how long it will take to turn BTB solution from blue to yellow. Again, you need to have a clock or watch with a second hand available. Rinse the beaker and fill it with exactly 50 ml of BTB. Now, inhale deeply. Then, using the straw, blow steadily into the BTB until the solution just turns yellow. In your journal, record how long it took for the solution to change color. This is your ‘normal carbon dioxide rate.” d Part 3. Exercise and check your rates again! Think for a minute about exercising vigorously, then.. . 1. Students might correctly predict that the amount of CO, goes up during exercise even if they hold the naive view that oxygen magically changes into carbon dioxide in the lungs. You might want students to try to plan this experiment in small groups. 1. Predict how your breathing rate, pulse rate, and“carbon dioxide rate” will change during vigorous exercise. Give reasons for your prediction. $ ’ l!ll A After making this prediction, take a few minutes to try to plan an experiment to test this prediction. Write out all the details of this experiment in your journal, including the equipment you’ll need and the steps you’ll follow. If you think you have a good experiment, check with your teacher before you proceed to do it. *** If you aren’t sure about how to set up this kind of experiment, you can follow the directions below: 1st: Exercise 2nd: Check and record your breathing rate and pulse rate 3rd: Check and record your “carbon dioxide rate” d H. Get your apparatus ready to teat your breath right after you exercise. Use exactly 50 ml of BTB in your beaker to make an exact comparison with your “normal carbon dioxide rate.” I. Now, exercise vigorously by jogging in place for two minutes. Time yourself. 38 Michigan Department of Education Lesson 10 TG 38 d Michigan Department of Education LJ J. Immediately after you stop jogging, inhale deeply and start keeping track of the time. Then using the straw, blow steadily into the test solution until the solution just turns yellow. Record the time it took for the solution to just turn yellow in your journal. K. Count your breathing rate for 60 seconds and record this data in your journal. L. At the same time you’re counting your breathing rate, have a partner count your pulse rate for 60 seconds and record this data too. 2. a) breathing rate up pulse rate up “carbon dioxide rate” is faster b) more 2. a) What differences did you notice in the three indications of your body rates before and after exercise: breathing rate, pulse rate, and carbon dioxide rate? Was your prediction from #l confirmed? b) If your breathing rate is higher, what does this mean about the amount of oxygen you’re taking into your body? c) What do you think it means that your pulse rate is different? Think about food and oxygen when you answer this question. d) Draw a conclusion from your BTB tests: Are you exhaling more or less carbon dioxide after exercise? e) What evidence do you have of this? f) Here’s the clincher question: Where in the body do you think this additional carbon dioxide must come from? (Want a hint? During your jogging exercise, what specific parts of your body needed extra energy?) iJ 3. Before going on to Lesson 2, think about the evidence you have just gathered, and write a briefbeginningexplanation of what you think seems to be happening inside your body when you use food during exercise. So what’s actually going on in your body to produce carbon dioxide? What does your body do with the oxygen you breathe? What’s actually going on to get the energy out of food for your body to use? We will use the evidence we’ve collected so far, along with some more evidence we’ll collect in Lesson 2, to find good answers to these questions. We will take an imaginary trip down into the cells to see what’s really going on. Food. Energy, and Growth 3s c) the heart is pumping blood faster around your body, delivering oxygen and digested food to the cells d) more e) it took less time to turn BTB yellow from the muscles - more specifically, from muscle cells. This is a very important concept, one that students routinely don’t master, that carbon dioxide is produced in the cells and travels back to the lungs and out of the body. Students typically think that carbon dioxide is simply exchanged for oxygen in the lungs. If they can trace the oxygen going to the cells and the carbon dioxide coming back from the cells to die lungs, then they are less likely to hold on to the misconception. 3. If students say that cells (or muscles) need food and oxygen when they do work, and the cells (or muscles) release carbon dioxide, they’ve got the idea for this lesson. They don’t need a detailed explanation of cellular respiration, since that comes in the next lesson. This lesson simply provides them with empirical evidence that they’ll need to understand cellular respiration. Lesson lo I Food, Energy, and Growth TEACHER’S GUIDE TG 39 Lesson ll * NOW YOUR BODYACTUALLY GETS ENERGY OUT OF FOOD Have you ever heard the statement: “Your body burns food to get energy?” Have you ever thought about what this means? Take some time to think about it now: What connectiona can you see between burning paper or wood and what your body does when you exercise? Share your thoughts with your classmates. Key Question How does the energy in food become energy that your body can use? Since it is difficult to investigate in our own bodies how we might really “bum food,” we will investigate it by first burning a sample of food outside of our bodies, and then making a few comparisons with what happens to food inside our bodies. You can burn a peanut or walnut as well as this butter - all produce carbon dioxide. But using the butter candle rather than a flaming peanut sets up question #3 on p. 41, which is important to help establish the idea that this is a chemical change. (Margarine does not work well as a substitute for butter.) The butter candle also produces water, which can be seen easily by placing a cold plastic plate over the candle and noticing the moisture that condenses. This is not done in this activity, nor is the production of water discussed at length, because it is difficult to establish some evidence for stndcnts of water production in the cells. The water we breathe out, for example, is not necessarily produced in cells during cellular respiration; we arc constantly drinking water and there is water all over our bodies, so there is naturally water vapor in our lungs. 4% This: Build a butter candle A. Cut about one inch off from the end of a stick of butter and place it in a Petri dish. Shape the butter into a small mound. B. Using a pencil or other sharp object, poke a hole into the top of the mound of butter. The hole should go about halfway through the mound from top to bottom. C. Insert a 1” to 2” piece of cotton string into the hole and secure the string by gently pushing and then pinching the butter around it. Only the very end should be exposed, like a candle wick. D. Light the wick and observe your candle. Record your observations. 40 Michigan Department of Education Lesson Statement: Students make and a observe a burning butter candle, They compare the reactants and products of this energy-producing process to the same process in their Lesson 11 TG 40 own body, Purpose: To develop an understanding of the process of cellular respiration by comparing it to burning butter. Approximate Time: 2 class periods Michigan Department of Education E. While the candle is still burning, test the air around it by pouring a little BTB into LJ the Petri dish around the base of the butter candle. Cover the candle and Petri dish with a 250 ml beaker, so the spout on the beaker is under the BTB. Let it continue until the flame goes out. Then swirl the Petri dish, candle and beaker slightly and look for any color change in the BTB. Record your observations. 1. releases energy; produces carbon dioxide. 2. stored in the butter. Some students may suggest that the energy was in the flame that lit the candle - see comment below. 1. What evidence do you have that the burning butter candle is like whatever is going on inside your body when you use food. Think about Lesson 1. Describe your evidence in terms of energy and substances. 2. When the butter candle burned, it released light and heat-both forms of energy. Where do you think that energy was before the butter burned? 3. a) When you watched the butter candle, you saw it burn and melt. Which of these changes do you think caused the carbon dioxide to form? b) Do you think that what happens to the butter you eat is a chemical or physical change? Why? 4. What do you think would happen if you let the butter candle continue to burn with the beaker over the Petri dish? Do you know what substance in the air is needed for paper, wood, or even butter to burn? LJ So what might be going on inside your cells when you need energy? What do we know so far? From Clusters 1 and 2, we know that l Digested food goes to your cells. l Oxygen goes to your cells. So far in Cluster 3, we know that more carbon dioxide comes out of our body when we exercise, so can we conclude that l Carbon dioxide is produced in cells when food is used for energy. Also, from the difference between burning and melting, we know that l Whatever is happening in your cells is a chemical process. Food, Energy, andG Growth G 41 Where does the energy come from? Energy released by the butter,both in the candle and inside one’s body, is stored as chemical energy in food-a type of potential energy. The energy released is not produced by changing matter into energy. Instead, you can think of energy as being “locked up” in the glucose when it is made by plants-this energy originally coming from the sun-and unlocked in cellular respiration. Students may understand this from their earlier studies of photosynthesis or energy flow in ecosystems. But the concept of potential energy is still often vague. Sometimes students believe that the energy they see in the candle simply came from the match that was used to light it. If this is what (continued on next page) Food, Energy, and Growth TEACHER’S GUIDE 3. a) Burn b) It’sinterestingtolistentostudents’ views on this. Allow them to debate it for awhile. Ask them whether gas is given off when other things melt, like ice. We’re trying to establish the important idea that this process of releasing energy involves a chemical change (actually many chemical changes.) Melting is only a change in state and, in fact, the butter absorbs energy from the burning process as it melts. Burning is a chemical process that changes the butter into new chemical substances. 4. Oxygen is needed. Eventually, the oxygen under the beaker would all be used up and the candle would go out. As the candle burns under the beaker, students may notice the level of BTB inside the beaker going up. This is not the crucial observation (the color of the BTB, indicating released CO,, is) but some students might ask about this. It is because there is more oxygen used by this chemical reaction than carbon dioxide produced, reducing the number of molecules inside the beaker, and therefore reducing the pressure. The outside air pushes up the water from the outside. rl Lesson II 11 II el TG41 Cellular respiration is a chemical reaction-actually a series of complex chemical reactions summarized by the equation shown here-that essentially rearrange the atoms of the reactant substances (glucose and oxygen) to form new substances (carbon dioxide and water), and in this case, release energy. Burning butter is a chemical reaction which requires oxygen (so is burning wax in a candle, or burning wood or paper.) No matter is lost in this or any chemical reaction: the mass of water and carbon dioxide produced is exactly the same as the mass of glucose and oxygen that react together. You can see this by noticing that the equation is balanced: all the atoms that go into the reaction come out again. The energy stored in the original molecules is released for use in cell processes. You may wish to discuss with students what happens when one is deprived of oxygen, as in carbon monoxide poisoning. Actually, death is caused because cells are not getting the oxygen they need. The first cells to be effected are usually brain cells and people become light-headed and pass out very quickly. Cells are deprived of oxygen because carbon monoxide will attach itself to the hemoglobin of the red blood cells 250 times faster than oxygen will. Also, it attaches more strongly than oxygen so it Building on your conclusions Yes, a very complex set of chemical reactions in going on in cells that release the stored energy from glucose. Oxygen is needed to make these reactions occur, and carbon dioxide (and also water) is what's left after the reactions occur. To simplify these reactions, scientists write one equation: C$I,O, + 6 0 , F SH,O t 6C0, releasing glucose t oxygen F water t carbon vapor dioxide What this looks like in a cell is this: The glucose and oxygenmolecules react, and the stored energy is released! The chemical reaction produces water and carbon dioxide, which leave the cell. This process that cells use to get energy from food is called cellular respiration. It is the reason why you can’t live more than a few minutes if you atop breathing. If cells can’t get oxygen, they can’t get the energy out of food, and they die very quickly. What would happen to you if your brain cells couldn’t get oxygen? *** does not exchange with oxygen. As a result, the oxygen-carrying capacity of blood is drastically reduced and cells are What’s the difference between a burning butter candle and what goes on in your cells? no longer getting the oxygen they needthus dying of asphyxiation. 42 Lesson 11 TG 42 Michigan Department of Education many of your students think, then point out to them that the candle burns much longer than the match, indicating that there must be some additional energy (lots, actually) in the butter itself. If they believe that it is only the wick that is burning, have them try burning a wick by itself along side the candle: Which burns longer? You may need to use an analogy for chemical energy changing into heat or light energy, such as in a light bulb or electric stove, where electrical energy is changed into heat and light energy; or in a fan, where electrical energy is changed into mechanical energy. Michigan Department of Education Cellular respiration is very similar to the process of producing energy in the form of heat and light when you burn a marshmallow or butter: Both require oxygen; both release energy stored in the food, both produce carbon dioxide and water. There is a difference though: Your body cannot bum food with a flame, and it doesn’t need or produce light energy. But it does need and produce heat energy, which is used to keep your body warm-much warmer (usually) than the surrounding temperature of the air. Also, burning butter provides too much energy too fast. Your body needs energy all of the time in much smaller, controlled amounts. H OW does it do this? How does cellular respiration release small amounts of energy? By using only small amounts of glucose and oxygen? Yes, there’s not nearly as much glucose in any cell as there is butter in a butter candle. But there’s more to this story. Cells are very complicated. Inside cells, the energy released from glucose isn’t used up right away. Most of the energy goes into many special molecules in each cell called ATP molecules. Each of the ATP molecules can store the energy from glucose in very small usable quantities-unlike a candle, which burns quickly and releases energy quickly. These energy-rich ATP molecules travel all over the cell, supplying energy when needed by cells, for motion in muscle cells, for light in the light-producing cells of the firefly, or for electrical signals in brain cells. The chemical formula for fat in the butter candle is different from the formula for glucose. A typical fat present in butter is glyceryl tristearate and the chemical formula is C&I&,0,. Notice that both glucose and the fat contain only carbon, hydrogen and oxygen. Both bum to produce carbon dioxide and water, releasing energy. In our bodies, fats need to be converted to glucose before they can be used in cells for energy. The heat produced by the process of cellular respiration is used to keep our body temperature at 98.6F (37°C.) As warm-blooded organisms, our body temperature stays constant and we maintain a stable internal equilibrium. The reason we perspire when we exercise vigorously is to help get rid of excess heat from the additional cellular respiration. As water evaporates from our skin, it takes with it some of the excess heat being produced, thus cooling our skin. ii) TqT h'1s: In your journal, draw an outline picture of a human body, large enough to fill an entire piece of paper. Draw in a cell in a muscle in the forearm. Show in your drawing how food gets from the mouth to the cell. Show how oxygen gets from the mouth or nose to the cell. Show how carbon dioxide gets out of the body. *** Extending what you Know Why do you get tired when you exercise? Why do you sometimes get cramps if you exercise too long and too vigorously? 43 Food, Energy, and Growth We are deliberately not going into too much complexity with this discussion of the chemical process of cellular respiration. We have chosen instead to promote students’ depth of understanding of cell processes by putting them in the contexts of 1) breathing and exercise (Where does the carbon dioxide we exhale come from? Why do we breathe more quickly when we exercise); 2) growth (Where does the new material come from when we grow? What’s theconnectionbetween growing and eating well?); and 3) weightgainand weightloss (Why does exercise help us lose weight?) We consider these real-world contexts and these questions to be the substance of scientific literacy, rather than the complexity of cellular (con't on next page) Food, Energy, and Growth TEACHER’S GUIDE It might be interesting to allow students to ponder these questions for several minutes before continuing to read the page. Let them voice their ideas about why exercise makes one tired. You may want to press them to talk about food and oxygen in their explanations. and what the body needs food and oxygen for. I-l;i Lesson 11 TG 43 If you said you get tired when you exercise because you run out of food in your body, that would be a good guess, but most people have extra food-energy-rich fat-stored in their bodies just in case their glucose gets used up. (Thisisoneway that exercise helps people lose weight, by using extra fat.) What happens if your breathing can't keep up with your Other “real-world” contexts of respiration include yeast in breadmaking (as yeast consumes the sugar in the dough, its cellular respiration produces carbon dioxide, making bubbles that make the dough rise) and fermentation. But your body can’t store extra oxygen. You get whatever you ueed by breathing. When you exercise, do you need more oxygen? Well, if your muscles need more energy to move fast during exercise, then you’ll need more oxygen to release that energy from glucose. But if your muscle cells need energy faster than oxygen can be supplied to the cells by breathing, what happens? Your muscle cells can’t use glucose the same way if they don’t have 6 oxygen molecules for every glucose molecule. In&ad, a different chemical reaction takes place, one that releases much less energy than the cellular respiration reaction with 6 oxygen molecules does. And this different chemical reaction also produces an additional by-product (just like when a candle is short of oxygen, it can produce more smoke.) Because this by-product is produced faster than your blood can carry it away, it begins to build up in your muscles, causing pain and fatigue. That’s why your muscles ache and you get cramps! The by-product is lactic acid, which changes the pH in the muscles and keeps the muscle fibers from relaxing after they contract. Some forms of exercise automatically rest your muscles after each time you use them. Cross-country skiingir one example. Duringthe normal motion of push-glide, you use your muscles when you push. During this time, your cells release and use energy. Then you rest the muscles while you glide. This allows your body to continue to supply enough oxygen for the amount of energy required. Normal crosscountry skiing along flat ground is good exercise for your heart, but doesn’t necessarily wear you out! 5. Answers will vary but the following key points should be included: food supplies the substances needed by the cells for making new materials and for producing energy. (Be sure students include both uses.) glucose and oxygen are chemically changed in cells intocarbon dioxide and water vapor, releasing energy. the process is called cellular respiration. l l l 5. Please explain in your own words why you need to eat. Don’t forget to talk about cells in your explanation. 6. The oxygen from the air you breathe is carried to cells where it is used to release the energy from glucose. 6. What happens to the air you breathe in? 7. Where does the carbon dioxide in your exhaled breath come from? 7. It comes from all the cells of the body. It is produced by the cells when glucose and oxygen react chemically to form carbon dioxide and water, releasing On to the next lesson... 44 energy. Michigan Department L q Lesson 11 TG44 processes, and we hope that theknowlegde students construct as they search for answers to these questions will be retained by more students into their futures. Students’ conception of respiration: If students have heard the word “‘respiration” before, they generally think of it only as breathing. This is where the common confusion about oxygen turning into carbon dioxide in the lungs comes from. With this naive view of respiration, they miss the essential connection between oxygen and food, and that a chemical reaction is needed for the production of carbon dioxide. Michigan Department of Education Lesson 12 GROWING Most people know that you need to eat well to grow well. But just what does this mean? And how does food help a person grow? Throughout this unit we’ve said that food does two important things for living organisms (yes, not only humans, but dogs, cats, insects, bacteria, even plants!) It provides the energy they need for all of their body’s activities, and it provides the raw materials needed for growing and repairing damaged body parts. But what does it mean to say that food provides raw materials for growing7 1o help ~~~~ion a teenager This key question, which will be examined as this lesson continues, get How does food help a lizard regenerate a tail that assumes that students realize that when they grow, they actually have more material in their body than before-it’s not a case of getting larger like a balloon expanding. The questions that follow the key questions are intended to help students recognize this. How does food help a plant increase its size? As you grow between the ages of 5 and 15, you get much bigger and your weight increases. Your bones get longer. Your muscles get longer. Do they just stretch? 13 The important idea for this lesson is that As your bones and muscles get longer, you need more skin to cover them. Your body needs more blood to move food and oxygen to all of its cells. some material from food gets incorporated into bodies (cells) as we grow. Does your skin just stretch to cover your larger body? Does your blood just “thin out” to move over longer distances? Let’s think about one muscle as it grows: As it gets longer, does it weigh more? Is there more muscle material in it if it weighs more? Do you think that your body adds more muscle material to the growing muscle? Where do you think that extra muscle material comes from? *** Yes, it comes from food. But the tricky problem is: Since you don’t eat human muscle material, how do you get it? How do the animal and plant parts you eat become part of you? How can food materials that come from animals and Food, Energy, and Growth 46 Lesson Statement: Students go back to the model of the digestive system they made in Cluster 2 and use the amino acids from digested foods to make new protein. They make different arrangements of various numbers of objects to simulate they sythensis of proteins from amino acids. Purpose: To understand how our bodies grow by adding new materials to cells. Approximate Time: I or 2 class periods Food, Energy, and Growth TEACHER’S GUIDE Lesson 12 TG 45 5 0 YouWiIl Need: l l model from Cluster 2, Lesson 8 “molecules” of protein, fat, and carbohydrate ’ pine Get out the model of the human digestive and circulatory systems you made in Cluster 2. Find the piece of different shaped paper that represent each of the basic components of food-the carbohydrates, the proteins, and the fats. A. Place these pieces in the small intestine. They will represent, say, some broccoli and hamburger you just ate (plant and animal parts.) B. Then pretend that the food is being digested: Separate the food particles into their digested products, showing that proteins are digested into carbohydrates are digested into _ and fats are digested into -1 C. Move these digested particles through the wall of the small inteetine into the blood stream, and give them a ride to, say, a muscle cell in your forearm. What happens to them in the cell? This is the big question. ‘We already know what happens to glucose in the cell (what?) But what happens to amino acids? Think this through for a minute. If your body needs new material to add to muscles as they grow, but you can’t add the cow muscle materials in hamburger to your own muscles, where could this new material come from? From these amino acids? Yes. Just as proteins are broken down into amino acids, amino acids can be built back up into new proteins, the exact ones you need to make new muscle material! Your cells are tiny architects, building new muscle structures from the raw materials-the building blocks-of amino acids. D. Use the amino acid pieces of paper in your model to build new proteins by taping them together in new ways. In your model, these new proteins can be thought of as new muscle material. 46 Lesson 12 TG 46 Michigan Department of Education The role of vitamins and minerals in growth: Vitamins and minerals are essential for making the chemical reactions occur that combine amino acids into new proteins. They are not incorporated into the new proteins, but are co-factors with enzymes to make these reactions occur. Vitamins cannot be produced by the body, so they have to be eaten; and some are not stored in the body for very long, so they have to be eaten every day. Certain minerals have other functions also, such as calcium in the production of bone matter, iron in the production of blood hemoglobin, and phosphorus for nerve firings. Michigan Department of Education 1. Amino acids from our digested food are put together in cells to make new blood cells. individual amino acids arc j o i n e d in wpacial combinations to make all the proteins you need picture we’re constructing is fantastic! Cells building new muscle materialsusing the food we eat, digested into amino acids, to build new proteins that become part of the cell. As the cells get larger with this new material, they divide, making new muscle cells, and the muscle gets larger! Each cell is its own architect, building just the kinds of proteins it needs to make new cells. This 2. Same as blood. You might point out to students that since skin is different from blood, it must be made of different proteins, which must be made from different combinations of amino acids. Using the ideas we’ve just considered, try to answer the following questions. 1. How do you think new blood is made? 2. How do you think new skin is made? *** Optional experiment One of the difficult questions that comes up with the picture we’re constructing is this: How can your body make so many different kinds of proteins, for all of the different parts of all of the different cells your body needs? E. Nature actually has 20 different amino acids to work with. To see how many different proteins these 20 might make, start to build proteins yourself with just three different amino acids. Arrange them in as many different combinations as you can, using each only once. Each combination represents a new protein. How many combinations can you come up with? (This is like taking 3 different letters of the alphabet, and arranging them in as many different words as you can, where the words might come from any different language.1 F. Add a fourth, different amino acid to the three you already have. Begin arranging these four to make different proteins. How many combinations could you make with 4 different amino acids? Food, Energy, and Growth E. You could make 3 different combinations: ABC, ACB, and BAC. This assumes that ABC and CBA are the same protein, just turned up-side-down. Mathematically, the number of combinations is represented by 3!/2, which is (3 x 2 x 1)/2 = 6/2 = 3. With 4 different amino acids, you could make 4 !/2 combinations, or 12: ABCD,ABDC,ACBD,ACDB,ADBC, ADCB, BACD, BADC, BCAD, BDAC, CABD, CBAD 47 sl Lesson 12 Food, Energy, and Growth TEACHER’S GUIDE TG47 2O!/2 = G. How many different proteins could be made from various combinations of the 20 amino acids? Could you use a calculator to make some kind of approximation? Try it! Actually, scientists have analyzed many different proteins to find out which amino acid building block.6 they are made of. They have found that protein molecules consists of anywhere from 50 to more than 10,000 amino acid molecules, where each amino acid can be used more than once--in fact, they can be used numerous times. Think that gives nature enough combinations to play with? All of the proteins that make up our body parts are made by our cells-tiny little factories using amino acids from digested food as raw materials. When you grow, your cells make new proteins, and add them to their own internal structures. As the cell gets larger, it divides and forms new cells. More and more cells are added to your muscles (skin, blood, etc.) as you grow. Your new cells come from the food you eat! As each cell m a k e s n e w proteins they a r e added to the c e l l As the cell g e t s 3. New proteins are made from the amino acids of our digested food. When the cell is big enough, it divides and , forms new muscle cells. all over. This is how you grow! 4. Vegetable and animal proteins in food are digested into amino acids, which are delivered to the cells by the blood. They are assembled into new proteins inside the cells. Glucose from our food provides the energy needed for all of these growth processes. 5. This process is exactly the same in animals as in humans. In this case, the new proteins are formed in cells in the tail stump. To review: 3. Explain, as completely as you can, what happens to a musclewhen you grow. 4. How does food help a teenager get taller? 5. How does food help a lizard regenerate a tail that gets tom off? 6. How does food help a plant increase its size? 6. Plants can make their own amino acids from the glucose they make in photosynthesis and the minerals they take in from the soil. Their growth process is essentially the same, then, as in animals. 48 Lesson 12 TG 48 Michigan Department of Education What happens to extra material from the food you eat that is not needed for energy, or that is not used for growing or repairing your body? Your body makes fat cells out of it! Extra food you eat that isn’t used for energy and isn’t used for new materials is stored by your body as fat cells for later u.se. Some animals do this to prepare for winter, when food is very scarce. Plants store extra food as starch (not fat) so they can live when there’s not enough sunlight to make their own food. (People also store extra carbohydrates as starch for short term Use.) Michigan Department of Education WEIGHT GAIN AND WEIGHT LOSS Lesson 13 44 tt All living things undergo continuous change during their brief span of life on earth. Fish get bigger, trees add new branches, crayfish regenerate damaged or lost parts, and people increase in size. In this lesson, you will use what you learned earlier in this cluster to help you understand the balance in your body between what goes in and what comes out. P 3 Questions Allow students to speculate about these key questions, without providing answers at this point in the lesson. Why does the food you eat make you grow and gain weight sometimes but not other times? What role does exercise play in weight gain and weight loss? Imagine two identical twins, Emily and Felicia. Each weighs 120 pounds. Emily is thirsty and so she drinks a pound (about a pint) of water. Feliciais very hungry so she eats a pound of spaghetti. For the purposes of this activity, consider all other food, water and activities of Emily and Felicia to be exactly the same unless indicated otherwise. Here is what happens to the weights of the two girls: Emily (wafer) Felicia (spaghetti) Weight before eating or drinking 120 lb. 120 lb. Weight right after Weight after In answering questions l-4, students are eating or drinking 121 lb. 121 lb. one day 120 lb. 120.2 lb. asked to do more than compare the effects of eating and drinking. They should speculate about what actually happens to food and water inside the girls’ bodies. Most answers will probably be incomplete at this point. Note where students difficulties are. Do you notice any pattern here? Both girls gained weight right away but lost mostofthatweightwithinaday. Felicia, though, didn’t lose quite all of the weight she had gained. 1. Why do you think Emily did not show any weight gain after one day? Explain what Emily’s body did with the water. 2. Why do you think Felicia showed a slight weight gain after one day? Explain what Felicia’s body did with the spaghetti. On a different day, Emily and Felicia both decided that they want to lose weight. Emily sat in a sauna for half an hour. She perspired a lot. Felicia ran for half an hour. She perspired a lot too. Here is what happened to their weights: Food, Energy, andGrowth 49 Lesson Statement: Students analyze several hypothetical cases of weight gain and weightlossanddecidewhatfactorscausedeacheffect. They make predictions for specific situations and write a plan by which they can attain their own goals. They explore the weight balance of all things that go into one’s body and come out. Purpose: To help students understand weight gain and weight loss both with regard to short term effects and Iong term effects. Approximate Time: 2 class periods Food, Energy, and Growth TEACHER’S GUIDE 1. Emily’s body used the water to help remove waste products through urine and feces; she lost the water in these ways over the long term, and returned to her original weight. 2. Felicia’s body used some of the spaghetti (the protein) to build new body cells, adding to her weight. Most of the spaghetti, however, was used forenergy, and the products of cellular respiration (carbon dioxideand water) were exhaled and excreted. 131 Lesson 13 TG49 3. Mostlybydrinkingwatertoreplenish what they lost through perspirationour bodies demand this from us after we exercise! 3. How did the two girls gain back the weight they had lost? 4. Notice that Felicia didn’t quite gain all her weight back. Why? What happened to that weight? Both girls lost weight shortly after their activities by losing mostly water due to perspiration. They gained it back by drinking. Felicia, though, also used some stored food for energy needed for running. Through cellular respiration, it changed into water and carbon dioxide, and left her body, reducing her weight. 4. She needed extra energy to make her body work faster than normal, so she used some of her stored body fat for that energy. It was changed to carbon dioxide and water, and exhaled. She actually lost weight by exhaling CO,! In general, you can do many different things that can cause you to gain or lose weight. Some of them make you gain or lose weight only in the short term. Others cause long term or permanent weight gain or loss. Let’s try to sort out which activities have which sorts of effects. 5. Look at the activities listed in the table below. Think about what things cause only short-term weight gain or loss and what things cause long term weight gain or loss. Thencopythefollowingtableandfillineachspacewithoneofthe following weight gain, weight loss, no effect or not sure. 5. (see table) 6. Long term weight gain: eating food that helps build new cells (proteins) or that can be stored as body fat. This food intake has to be beyond what the body requires for energy. Long term weight loss: exercise that uses stored body fat for its energy content, changing it into carbon dioxide and water. The carbon dioxide is exhaled, losing its weight. b. ones that only involve water intake or loss I [weight loss or no effect] [no effect] 6. a) Study your answers and make a statement about what sorts of activities lead to long term weight gain or weight loss. bb ) What sorts of activities have no long term effect? 50 Michigan Department of Education - Lesson 13 TG 50 Calories: We deliberately have not talked about calories in this lesson, allowing the idea of calories to come up as a question from students instead. Many students are familiar with the idea of “counting calories” for dieting, or have seen the caloric value of a serving of food on package labeling. “Calorie” (with a capital C) is a common unit of energy that refers to the amount of energy released from the food when it is oxidized in the body-one Calorie is equal to the amount of energy needed to raise one kilogram of water one degree Celsius. In dieting, people often try to restrict the amount of calories (Calories) they eat, which is not the same, of course, as restricting only the quantity of food eaten, since some foods have more calories per ounce (or Michigan Department of Education 7. How can you explain long-term weight gain in terms of how our bodies use food? Use the concepts of digestion and cellular respiration in your answer. 8. Explain, in terms of energy, how you can control how much long-term weight you gain or lose? 9. Why does eating sugar result in weight gain if it is stored as fat, but not if it is used in cellular respiration. 10. Tell what kind of diet would be good for each of the following situations. Explain how you made your choice. a) You are a body builder and want to add muscle to your body. b) You want to gain weight. c) You are planning an expedition to the Arctic and want to get your body ready for the trip. d) What does a bear need to eat as it prepares for hibernation? Body fat is not a bad thing. If you were exploring in the Arctic, you might have to go without food for several days. Excess food stored by your body as fat can be converted to glucose and used for energy when your body needs it. In times past, people might use body fat if crops failed or hunting was bad; body fat was important. In those situations, some people without some stored energy would weaken and perhaps die. Today, for people who never go hungry, the excess fat their bodies store is no longer useful. Because fat can cause serious health problems such as heart disease and high blood pressure, we need to keep our bodies from storing too much fat. *** 11. What do you want for yourself-weight gain, weight loss or just maintain your current weight? Write a plan that will help you achieve your goal. Tell why you think your plan will work. Food, Energy, and Growth 51 gram) than others. Generally foods high in calories (by weight) contribute more to body fat than those low in calories. But energy is needed by all people, even if they are dieting, so they have to maintain some minimal caloric intake-this is why bulimia or other forms of not eating are dangerous: Without any food, our bodies have no energy and no materials for growth and repair. New dietary guidelines recognize that foods high in saturated fats contribute more to body fat (and heart disease) than those of similar calorie content that are low in saturated fats. Food, Energy, and Growth TEACHER’S GUIDE 7. Digested food(imarily amino acids and fatty acids) can be used for growth or for storage of fat; both result in weight gain. If digested food is used for repair or for cellular respiration, there will not be any long-term effect. 8. If you want to gain weight, take in more food for energy than what your bodyneeds. Itwillbestoredasbodyfat, adding to your weight. If your body needs more energy than what’s stored in the food you eat every day, it will use stored body fat for that extra energy, changing it to carbon dioxide and water, and exhaling the carbon dioxide. 9. When it is stored as fat, it adds to the weight of the body. When it is used in cellular respiration, it is changed into carbon dioxide and water vapor, and expelled from the body. 10. a) A diet rich in protein will provide aminoacidsneededforbuildingmuscle. b) A diet high in carbohydrates and especially fat will provide the excess needed to gain weight. c) Fats have twice as much available energy as carbohydrates (that’s why they taste so good.) Eat lots of carbohydrates and fat to store up extra energy. d) Lotsoffattostoreupextraenergy for the body to keep warm and function during the long winter (Although bears don’t actually hibernate-their body temperature does not drop significantly-they are much less active because food is much less available. In the same way, plants store food in the form of starch in the roots for use during the spring, before their leaves begin producing their own food.) 11. Answers vary s Lesson 13 TG51 Nature is a meticulous bookkeeper. Nothing is ever lost or gone. It just changes into new or different forms. This is one of the most fundamental laws of nature: In chemical reactions like cellular respiration, matter can neither be created or destroyed. It can be changed only from one to another. In the case of cellular respiration, matter is changed from one form (glucose and oxygen) into another form (carbon dioxide and water.) But you can keep track of the amount of matter, even if it changes form. Every ounce of food you put into your mouth, and every ounce of air you breathe into your body through your lungs, has to be accounted for in either the weight you gain or the substances you release from your body (including when you g o to the bathroom, when you breathe out oxygen and carbon dioxide, and when you perspire.) Every Ounce 12. Rewrite the following statements in yourjournal, and fill in the blanks with one of the following: equals (=), is greater than (>), is less than (<) 12. = > < If your weight stays the same: ALL THE STUFF ALL THE STUFF THAT GOES IN 0 THAT COMES OUT So, if your weight increases: ALL THE STUFF ALL THE STUFF THAT GOES IN c l THAT COMES OUT So, if your weight decreases: ALL THE STUFF ALL THE STUFF THAT GOES IN 0 THAT COMES OUT The idea that the mass of the food we eat has to be conserved is especially difficult for many students. They don’t always easily recognize that the amount of substance we excrete (including water vapor, perspiration, carbon dioxide, and excrement) is less than the amount we consume and breathe in, by just the amount that is used to build new cells or stored as fat. We can actually keep what bookkeepers call a "balancesheet”of the matter that goes into your body and the matter, that comesout. Start bydrawingachartsimilarto the one on the next page (make a copy in your journal, don’t write in this book!) Then follow what goes in and what cornea out during one day of your life. Say you weigh yourself before breakfast and weigh 155 lbs. Then you eat a bowl of cereal with a cut-up banana and a glass of orange juice. It weighs 1.2 pounds. Record this on your balance sheet (as shown in the example.) Later in the morning, you go to the bathroom. This is only liquid waste, and it weighs 0.3 pounds. Enter it on the third line in the appropriate column. Keep track of how your weight is changing through each of these activities. 52 Michigan Department of Education Weight loss during exercise: What is it that's actually lost when weexercisethataccounts L Lesson 13 TG 52 for long-term weight loss? It’s not the fluids we lose from perspiration, because our bodies demand us to drink water after exercise, to replenish the lost water. It’s not the heat energy that radiates away from our bodies when we exercise, because heat energy has no mass (nor is matter being converted to energy.) It’s the carbon dioxide, produced by cellular respiration of carbohydrates and stored fats, that leaves our bodies through our breath. This is why exhaled air has more mass than inhaled air, because of the extra carbon dioxide, which has more mass per liter than oxygen. When we store body fat from eating foods, we’re gaining weight; when we use stored body fat for extra energy during exercise, we are changing it into carbon dioxide Michigan Department of Education Materials In beginning weight breakfast bathroom Materials Out Here are the calculations For inhaled air: nitrogen molecular weight 28 g/mole x 79.02% (.7902) = 22.126 g/mole of air oxygen molecular weight 32 g/mole x .2095 = 6.704 g/mole of air carbon dioxide mol. weight 44 g/mole x .0003 = .0132 g/mole of air Add the three together = 28.843 grams total per mole of inhaled air Weight 155 Ibs. 1.2 Ibs. 28.843 g/mole x 1 mole/24.5 1 (room temp, 1 atm) x 5 liters/breath = 0.589 g/ breath inhaled air Let’s say you also go to the bathroom again later in the morning, and this time the liquid and solid waste together weighs 0.8 pounds. Record that in the appropriate column of the fourth line. (Is excretion “materials out” or ‘materials in?“) What else goes in and out of your body besides food and excretion? Your breathing takes in air, and when you exhale, you lose air. Can we figure out how much a lungful of inhaled air weighs, and a lungful of exhaled air? Using Mathematics How is the air that you breathe in different from the air you exhale? The air you exhale has more carbon dioxide in it from cellular respiration. Inhaled air is 20.95% oxygen, 0.03% carbon dioxide, and 79.02% nitrogen (with a little bit of argon and some other gases.) Exhaled air is 15.8% oxygen, 4.0% carbon dioxide, and 80.2% nitrogen (and small amounts of other gases.) Gases don’t weigh much, but over a 24 hour period, especially if you exercise and increase the rate of producing carbon dioxide, you wind up breathing out measurably more weight (in gases) than you breathe in. How much more? You can figure this out with some math-just arithmetic, nothing fancy. An average lungful of air (about 0.5 liters) that you breathe in weights 0.589 grams. If you breathe 14 times per minute (and there are 454 grams in 1 pound), how many pounds of air do you inhale in the moming(say 5 hours)? Add this to your balance sheet, in the appropriate column. An average lungful of air (0.5 liters) that you breathe out weights 0.597 grams. Again, if you breathe 14 times per minute (and there are 454 grams in 1 pound), how many pounds of air do you exhale in the morning (5 hrs.)? Add this amount to your ledger, too. Food, Energy, and Growth 53 and water, and releasing the carbon dioxide. The increased pace of cellular respiration during exercise generally requires the use of stored body fat (which can be converted into glucose), unless the person eats a big meal first. People who are deliberately trying to lose weight by exercise usually restrict the amount of food they eat so that they will draw on stored body fat during the exercise, thereby changing it into carbon dioxide and water and releasing the carbon dioxide. In this chemical reaction, mass is conserved (the mass of glucose and oxygen equals the mass of carbon dioxide and water as the reaction takes place in the cell) but our body weight decreases when we exhale the carbon dioxide. (continued on next page) Food, Energy, and Growth TEACHER’S GUIDE 0.589 g/breath inhaled air x 14 breaths/ min. x 60 min/hr x 5 hr x 1 lb./454 g = 5.449 lbs. of air inhaled in 5 hrs. Similar calculations for exhaled air, using the other percentages, yield 5.523 lbs. of air exhaled in 5 hrs. To calculate inhaled & exhaled air for 6 hrs. (one afternoon) or 13 hours (from 6 p.m. to 7 am.) - used on next page divide the figures above by 5 to get weight per hour, then multiply by 6 or 13 as needed. (When we talk about “weight” of air, we are really using the common units of pounds to refer to a mass equivalent. The actual weight of air-as measured on a scale-is less than these figures because of bouyancy. Once the air is dissolved in body fluids, its mass and weight are equivalent.) Another approach to these calculations is by using the fact that fat contains 9 calories of energy per gram (where carbohydratesandproteinscontainabout 4 cal/g.) For every 9 calories of energy you use exercising, you could be “burning off’ 1 gram of fat. 45 grams is about .1 lb. Lesson 13 If you don’t exercise, you will not find much difference between what you breathe in and what you breathe out in a day. Exercising speeds up your breathing rate (as you know from Lesson 10). The difference becomes significant: you lose more weight (in the form of carbon dioxide) than you take in. When Felicia ran for a half-hour, she had a long-term weight loss of 0.1 lb. This was the carbon dioxide she lost from cellular respiration of stored body fat, excretion I I 0.3 I I Then record these other activities during your day, making sure to get them in the right columns: J exercise I I 2.0 So say you exercised vigorously for a half-hour in the morning by playing basketball. You lose 2 lbs, mostly from perspiration. Record this weight loss. Then you immediately drank water from the drinking fountain: Record 1.9 lbs. of water added to your body. Then you went to the bathroom around 11: Record excretion of urine, 0.3 lbs. I lunch bathroom after lunch air in during p.m. air out during p.m. more exercise in school drinking liquid liquid and solid waste a bike ride drinking liquid 1.4 lbs. (turkey sandwich, fruit, milk, cookie) 0.3 lbs. 6.539 lbs. (for 6 hours) 6.628 lbs. O.llbs.lostofcarbondioxide& 1.91bs.perspiration 1.9 lbs. 0.8 lbs. 0.05 lbs. lost of CO, & 0.6 lbs. perspiration 0.6 lbs. dinner bathroom air in during night air out during night move some boxes drinking liquid bathroom before bed urine when you wake up 1.6 lbs. (you liked it!) 0.3 lbs. 14.167 lbs. (for 13 hours) 14.360 lbs. 0.04 lbs. of CO, (light exercise) & 0.5 lbs. perspir. 0.5 lbs. 0.8 lbs. 0.6 lbs. . 9 . B_ 13. Down by .746 lbs. (see spreadsheet above) 13. After you fill in the entire balance sheet, has this person’s weight gone up or down over this 24 hour period? 14. Probably the person will gain weight, although it is hard to tell by looking only at one day, since less than 2 cups of milk would throw the balance in the other 14. If this person continues to eat like this and exercise like this, what will happen to his (or her) weight? direction. 54 Michigan Department of Education The effect of exhaling carbon dioxide is relatively small, as shown by the calculations. Larger weight loss by people who arc on a regular exercise routine may occur as their general hunger or desire for food is diminished by the exercise routine. Lesson 13 -A TG 54 Michigan Department of Education 15. If weight was lost, less food was taken into the body, and/or stored fat was used for energy. 15. How might this person’s day have been different if he or she lost a pound and wound up at 154 pounds after this 24-hour period? (Talk about his or her food intake and exercise during the day.) 16. How might this person’s day have been different if he or she gained a pound and wound up at 156 pounds after this 24-hour period? (Talk about food, exercise, and growth in your answer.) 16. If weight was gained, more food was taken into the body, and/or the person became less active, utilizing less of their stored body fat. If your class chooses to do the next cluster, you will take a close look at several different diets, including your own, and see if you’re eating well-if all the nutrients necessary for energy and for growth and repair are present. You will also look at the diets of several other cultures to see how they meet all of their dietary needs. If your class decides not to do the next cluster, you will still be able to look at, think about, and make good decisions about what you eat. You now know why it’s important to eat certain foods, and what happens to those foods inside your body. You know what foods give you energy, and which help you grow and keep all your cells in good repair. And you are now better prepared to think critically about food and health news and comments you hear on TV and read in the paper. Keep your ears and eyes open: Good advice about eating well is all around usand so is the good food! Food, Energy, and Growth 55 Lesson 13 Food, Energy, and Growth TEACHER’S GUIDE TG 55 TG 56 Michigan Department of Education Laboratory Background Information for Cluster 4 Lesson 14 DIET AND NUTRITION: WHATDO YOU EAT? Many students have only very general knowledge about foods that are good for them and those that are not. They have little or no knowledge about what constitutes a balanced diet. In this activity, they will use the most recent information about healthy diets from the U.S. Department of Agriculture to analyze 3 diets-one that could use a lot of improvement, one that is quite healthy and their own. They will come up with suggestions on how they could make theirs healthier. MATERIALS 3 blank “food pyramid” charts for recording data (in appendix), one marked Marta’s diet before food unit, one marked Marta’s diet after food unit, and one for student’s own diet. It will help studentskeep track of which is which if they are copied on different color paper. Also, chart of protein, carbohydrate, and fat content of various foods (in appendix). J If you want to show relative amounts of foods by “serving size," as indicated on p. 56, you will also need bran flakes, a bowl, peanut butter, and 2 slices of bread (maybe some jelly too, in case somebody wants a snack.) PITFALLS AND CAUTIONS 1. It will be necessary to estimate number of servings, grams of fat, etc. based on information in the margins of the “Eating Right Pyramid,” but it should still be possible to come up with a pretty good estimate of how healthy a diet is. 2. Whenever possible, students should keep the package information as this will help greatly in analyzing the diet. 3. New regulations on labelling from the Food & Drug Administration, which are just beginning to go into effect and will be phased in over the next several years, should be very helpful in the future for those who are serious about eating healthy diets. Lesson 15 DIET AND NUTRITION: WHATDO~EXI’? Students do research to determine how people who eat little or no meat can have healthy diets. This research requires them to 1) survey vegetarians; 2) do library research; 3) ask experts. We want them to construct the idea that all the amino acids one’s body needs can be eaten in a diet that blends legumes with grains. They then look at the staple diets of other cultures, building an appreciation for the healthy and diverse diets that have been created by cultures that have little or no access to meat on a regular basis. Food, Energy and Growth TEACHER’S GUIDE lab prep 15 MATERIALS AND ADVANCE PREPARATION Chart of nutrients in various foods (in appendix.) You may want to arrange to have students use the library during your class period. They will probably need no more than 2 days for this assignment. For those who are “asking an expert,” you might want to contact the local county extension agency or university and set this up ahead of time with a nutritionist, or arrange for a nutritionist to visit and talk to your class. lab prep16 Michigan Department of Education DO WE GET WHAT WE P-@ NEED FROM W H A T W E E A T ? c, 4 * Often when people think about getting what they need from what they eat, they immediately start wondering if they have enoughvitamins and minerals in their diets. They often don’t think about proteins, fats or carbohydrates. Vitamins and minerals are important, although when people eat good food on a regular basis they get the vitamins and minerals they need. Actually, proteins and carbohydrates really make up most of the food you eat. If you didn’t get enough protein in your daily diet, what wouldn’t happen? If you didn’t get enough carbohydrates in your diet, what wouldn’t happen? In this cluster, you will analyze your diet, and diets of other people around the world, to see if you and they get enough of what you need to grow, to move, and to think. Food, Energy and Growth Food, Energy, and Growth 57 TEACHER’S GUIDE Lesson 14 / c DIET AND NUTRITION: What do you eat? You know how important it is for your body to get enough proteins and carbohydrates from your food. But how can you tell what’s in the foods you eat? How do you know how much proteine, carbohydrates, and fats are appropriate for you? Teachers should encourage student speculation here, but should not provide answers at this; point. Key P Question How can you be sure that you get what you need from your food every day? You will try to figure out whether or not your diet is healthy for you, whether it gives you what you need to grow and repair your body, and has the energy you need. First, you need to have a complete list of what you eat-a diet diary. A. List everything you ate yesterday, from memory, on one sheet of paper. Then, on another sheet, list today’s breakfast and/or lunch, any snacks, everything you ate today. Take the list with you and keep recording all your food until you go to bed. Bring it in tomorrow. Don’t cheat. Only you will aee this list, so make it complete. B. Then, you’ll need some way of figuring out how much protein, carbohydrate, and fat you get from your food. How could you figure this out? One way is to do food tests on everything you eat, like we did earlier in this unit. Were those tests able to tell you how much protein, for instance, was in a piece of cheese? Not really, not the way we did them. They could tell you ifprotein was in cheese, but not how much. But it seems possible to construct a teat like those to tell how much protein, or carbohydrate, or fat is in a certain amount of food. In fact, food and nutrition scientists have done this, and their results are on many packages of food you eat! Here’s what a food analysis of bran flakes cereal looks like, taken right off the aide of the box: 58 Michigan Department of Education Lesson Statement: Students compare foods based on nutrition information on food Lesson 14 TG 58 labels. They consider “common sense” guidelines for eating well and compare these to the “Eating Right Pyramid,” Then they examine their own diets and two make-believe diets, Purpose: To enabIe students to use food labeling and other tools for constructing healthy diets. Approximate Time: 4 class periods Michigan Department of Education 1 oz. bran flakes 90 3g carbohydrate 23 g fat og cholesterol Omg calories Protein with l / 2 cup skim milk 130 7g 29 g og Omg with l/2 cup whole milk 160 7g 29 g 4g 15 mg For comparison, here’s what a food analysis of "crunchy” peanut butter looks like: 2 tbs. peanut butter calories 130 protein 9g carbohydrate 5 g C. Compare bran flakes with skim milk to peanut butter. In yourjournal, enter the nutritional information for "bran flakes with milk in one column and "peanut butter” in another, right next to it, to make it easier to compare. 1. Which would give you more protein? 1. peanut butter 2. Which would give you more fat? 2. peanut butter 3. Which would give you more carbohydrates? 3. bran flakes with milk D. Try serving yourself 1 oz. of bran flakes with 1/2 cup of milk, and 2 tablespoons of peanut butter (maybe on a slice of bread) to see if these nutritional analyses are really for what you would consider to be 1 serving. 4. Is 1 oz. of bran flakes with 1/2 cup of milk exactly what you would eat for breakfast? Is 2 tablespoons of peanut butter exactly how much you’d eat on a sandwich? 5. Are these comparisons true no matter how much you eat of either of these foods? E. Now do this kind of comparison with other foods you eat. Create a chart to carry home with you, along with your record of what you eat, to collect nutrition information from the sides of food packages. Try to find information on many different foods, both ones that you think are healthy and ones that seem like junk foods. ‘I’ry to get some that are high in protein, some that are Food, Energy, and Growth 4. Probably no for bran flakcs. Probably yes for peanut butter. 5. No. The assumption underlying the comparisons of nutritional information on package labeling is tbat the amount indicated represents 1 serving. Often it doesn’t. 59 Lesson 14 U Food, Energy, and Growth TEACHER’S GUIDE TG59 high in fat, some that are high in carbohydrates. Try to find information on the foods that you tested in Cluster 1. 6. Meat, eggs, bulk foods, soda pop, any foods that are already prepared, like from a deli, or food delivered to your home, like pizza. Also highly prepared foods, like cakes and pies. You might find out by calling a nutritionist at a university, a hospital, or the county extension 4-H office. 6. What kind of foods do you think don’t come with nutritional labeling7 How could you find out what a nutritional analysis of those foods would be? Tomorrow you11 look at the nutrition information you’ve gathered. But before you can really use this to help you know what kindof diet is good for you, you need to think about a few common sense rules. What common sense rules do you know about eating healthy? Brainstorm them and list them on the board or on a piece of paper. *** Here are a few: l l l 7. Common senseruleshelpusmaintain healthy bodies, even though we don’t of red meat, or lots of cheese, or lots 7. Why do we have these common sense rules? Explain why you think each one is important. fully understand why certain foods are good or bad for us. Sweets contain sugar, which gives you energy, but also causes cavities. Actually, the energy in sugar is released much faster than the energy in non-sugar carbohydrate foods (like cereals and pastas). so that nonsugar carbohydrate foods are actually better for continuing to get energy between meals. Fats in foods, especially saturated fats,, tend to clog arteries and lead to heart disease. Fruits and vegetables contain lots of good vitamins and minerals. 8. Rules might include eating lots of carbohydrates for energy; eating protein foods when you’re growing. 9. a) Answers vary, but foods high in fats or concentrated sugars should be avoided. b) Answers vary but a healthy diet consists of plenty of grains, fruits and vegetables. (See #7.) Don’t eat too many sweets. Don’t eat too many fatty foods, like lots of peanut butter. Eat lots of fruits and vegetables. 8. List any other rules you know about eating healthy. Try to make some up from what you’ve learned so far in this unit. Day 2 Now that you’ve collected all this nutritional information about different foods, see if you can eort it out in some way. F. Create several class charts for listing different types of foods -- one for foods that are relatively high in proteins, one for foods high in carbohydrates, and one for foods high in fats. 9. a) Look at your chart, and think about your eating rules. What foods should you stay away from, and why? b) What foods should you eat, and why? 10. Are you surprised by any of these foods, that they have more protein, or more fats, or more carbohydrates than you thought (or less of any of these)? 60 Michigan Department of Education 10. Answers vary. Nutrition information for common foods is listed in the appendix, in case you want to use some foods for comparison that no student brings back to class. Lesson 14 -A TG 60 Here’s a rule-of-thumb for the amount of fat in a healthy diet: Nutritionists recommend that no more than 30% of one’s daily intake of calories come from fats. This can be estimated easily from the amount of grams of fat one eats: Each gram of fat has 9 calories (compared to about 4 calories each for a gram of protein or a gram of carbohydrate): multiply the number of grams of fat in the serving by 9 to get the total calories from fat, then divide this by the total calories for the serving. Try this using the nutrition info on a candy bar. Michigan Department of Education Food Guide Pyramid A Guide to Daily Food Choices The U. S. Department of Agriculture has created a simple way to think about how much of different foods people should eat. It’s called the Eating Right Pyramid. Let’s see if you agree with their suggestions. 1 11. a) Which group(s) on the food pyramid are composed mostly ofprotein? b) Grains (Bread, cereal, rice and b) Which group(s) are composed mostly of carbohydrates? pasta) c) Meat and dairy products. If students have trouble with this one, point c) Which group(s) contain the most fat and oil? 12. Look at the shape of the pyramid and the recommended number of servings for each group of foods and tell why breads, g-rains and cereals are at the bottom of the pyramid and fats, oils and sweets are at the top of the pyramid. 13. Do your ideas about eating well fit with this food pyramid? Why or why not? 4 Try This Let’s test out what you know about eating well by looking at three different diets and analyzing them for proteins, carbohydrates, and fats. You will n e e d : for on4 day Blank charts for recording data * Marta's diets before and the food unit l Your own diet diary l Here’s what to do: Basically, you will look at three different teen-age diets: Marta’s (a fictitious character) before studying the unit, Marta’s diet after studyingtheunit, and your own sample diet for a day. You will analyze each diet, using nutritional Food, Energy, and Growth 11. a) Meat products out the key on the “Eating Right Pyramid” which shows fats by the small circles. 12. The bottom of the pyramid, which has the most space represents foods that you should consume in the largest amounts. Breads. grains and cereals are needed by bodies because they are good sources of long-lasting carbohydrates for energy. The top of the pyramid which has the smallest space represents food that you should consume in the smallest quantities. Fats and sweets are herebecausetheycancontributetohealth problems, including heart disease and cavities. 13. Answers vary. 61 CI Lesson 14 Food, Energy, and Growth TEACHER’S GUIDE TG61 You may need to help students figure out what the components of some preparedfoodsmaybe. Theyoftenhave trouble with this since their familiarity with food is primarily from the supermarket rather than from any actual food production processes. Even foods as common as cereal leave some students totally mystified about where it comes from. information from food labels and the food pyramid, to see which components are present and at what levels. A. Examine Marta’s diet diary for the day before she studied this food unit. Obtain a blank copy of the food pyramid and for each food consumed at breakfast, lunch, dinner and for snacks, find the proper food group on the pyramid and write the name of the food in that space. Items such as butter or margarine, jam, syrup, topping, nuts, etc. should be entered aeparately. MARTA’S SAMPLE DlETs Students will need to estimate servings in all of these questions. They should have less difficulty with their own diet if they kept an accurate food diary and if they kept the packaging information whenever possible. The wrappers from snack foods and any others that they can get will be very helpful in estimating serving size as well as obtaining grams of saturated or unsaturated fat and cholesterol. You will probably need to remind them that they should make the best estimate they can. BEFORE FOOD UNIT: AFTER FOOD UNIT: Breakkfast: 5 pancakes with butter and syrup, 4 strip of bacon. whole milk Breakfast: 2 poached eggs, 2 slice of toast with honey. skim milk, orange A.M. Snack: Sweet roll and soft drink A.M. Snack: Cottage cheese and pear Lunch: Hamburger, french fries. ice cream, soft drink Lunch: Broiled chicken, baked potato, apple, skim milk P.M. Snack: Candy bar and soft drink P.M. Snack: Raisins. apple juice Dinner: Steak, mashed potatoes with butler. peas. fruit cocktail. apple pie, whole milk Dinner: Steak, baked potato with SOW cream, peas, salad with b-cai dressing. cantabupe, cottage cheese, skim milk Bedtime Snack: Potato chips and soft drink Bedtime Snack: Yogurt and apple B. Count the number of servings of gmin products in Marta’s diet. Use the information on the chart next to the "Eating Right Pyramid” as a guide in counting servings. If packaging from any of these foods are available, the nutrition information on it may help you, especially when evaluating your own diet. C. In a similar manner, count the number of servings in the fruit and vegetable group. D. Count the number of servings in the dairy group and in the meat products group. E. Use the information in the “Eating Right Pyramid” to estimate how many grams of fat are in the diet. You will need to check through all the groups in the pyramid, but especially the dairy and meat products groups for fat and 62 Michigan Department of Education I Lesson TG62 Michigan Department of Education oil content since most fats and oils are consumed as part of other foods.. For example, potato chips are a vegetable but have large amounts of oil as do all fried foods. Many meats and dairy products have high fat content as does chocolate and most candies. F. Use the information in the “Eating Right Pyramid” to decide how many servings of concentrated sugars are in the diet. Again, you will need to check through all the groups in the pyramid but especially the carbohydrate and fruit groups. For example, pie is often a source of fruit but also contain concentrated sugars. Cookies and cakes have wheat or oats (grain) in the flour but also contain lots of concentrated sugars. G. Now compare "Marta’s Food Pyramid before food unit” with the “Eating Right Pyramid.” Be sure to examine and compare every food group. Remember that the pyramid is a guide of what to eat each day and how many serving. 13.a) Not very 13. a) How healthy is her diet? b) What suggestions can you make that will improve it? H. Now look at Marta’s diet diary for the day after she had completed the study ofthisunit. Beginwith anewblankcopyofthefoodpyramidandrepeatstepe A through G. b) Much less fat, meat, whole milk products, concentrated sweets and junk food I. Compare “Marta’s Food Pyramid after food unit” with the “Eating Right Pyramid.” Be sure to examine and compare every food group. 14. a) Quite healthy 14. a) How healthy is her diet? b) Make suggestions if you can that will improve it. b) Could eat less meat and more grain &%*a@ It’s one thing to criticize others for their eating habits. It’s harder to look closely at what we eat ourselves. J. Do the same kind of analysis on your own diet as you did on Marta’s diets. 15. a) How healthy is your diet? 15. Answers will vary. b) What changes could you make in your own diet that would make it healthier? c) What might keep you from changing the way you eat? 16. a) Which diet was the healthiest? Give reasons to support your answers. 16. Answers will vary. b) Which one was most unhealthy? Give reasons to support your answers. Food, Energy, and Growth 63 II Lesson 14 Food, Energy, and Growth TEACHER’S GUIDE l’G 63 DIET AND NUTRITION: How do others eat? Lesson 15 Most people in the United States eat fairly large portions of meat every day. It may be in a sandwich for lunch, or as part of dinner. Meat is almost always the main part of meals eaten in restaurants-think of what you eat in fast-food restaurants, or how menus are often organized by “beef, chicken & fish.” Meat is generally an excellent source of protein (although you wouldn’t want to eat too much meat with high fat-content.) Meat is considered a “complete” source of protein because all of the amino acids your body needs to make new cells are available in meat. This isn’t true of other foods that contain proteins. Grains (like wheat and oats), legumes (like kidney beans, black beans, and peanuts) and many vegetablea contain some proteins, but there are fewer types of amino acids in their proteins. None of them alone contains all of the amino acids your body needs. A. Look at your list of components of various foods. Write a list in your journal that ranks the tap tan foods by the amount of protein they contain. 1. Meats contain more protein than almost any other food. 1. What does this list tell you about the amount of protein in meat compared with other foods? 2. No 2. Can you tell from this list which amino acids are available from each protein-rich food? *** It’s a good thing that meat isn’t the only source of protein. Many people in the US., for various reasons, prefer not to eat meat-including chicken and fish. But vegetarians are healthy-they grow well and repair their cells as needed, just as do people who eat meat. Ten of the 20 amino acids can he made by the body, but 10 cannot; nor can they be stored in the body. The ten that cannot be made are called “essential” and need to be eaten every day. So what do vegetarians eat that gives them all of the amino acids they need for growing and building strong hody parts? In other words, how can a person construct a healthy diet that supplies all of the essential amino acids (and vitamins and minerals) without eating meat? 64 sl Michigan Department of Education Lesson 15 TG64 Michigan Department of Education This is a good question. It’s good because, first of all, it’s important. But, secondly, there are probably several different ways oflooking at the answers, and several different ways of finding answers. How could you find an answer to this question? How could you and your classmates together, acting as a research team, come up with good answers to this question? *** Here’s how you might begin: Assign small teams of investigators to try several different approaches to finding this out. One team could seek out and survey several people who follow vegetarian diets, and ask what they do. Another team could try working with a librarian to find library resources that might help. A third team might try calling experts, like a nutritionist at a university or county extension agency. l Do a survey l Use library resources l Talk to experts After each small team of investigators ha8 compiled information from their own inquiries, then your entire class should come together to pool the information you’ve gathered and try to synthesize an answer to the question that makee sense to every team. B. After conducting small group research, hold a c l a s s discussion where each group reports on their research and writes key ideae on the board. At the end of all presentations, have several people try to summarize all three reports and construct a good explanation of how vegetarians construct diets that provide all their protein needs. Food, Energy, and Growth 65 Here’s what students will probably find out: While meat is a “complete” source of protein, certain other foods can be combined to provide all of the amino acids that our body needs. Corn (for example) is short on the amino acid lysine, but rich in methionine. Soybeans are rich in lysine, but short on methionine (as is milk.) So if a person eats both corn and soybeans at the same meal, all of the essential amino acids are present in her digestive system, for making new human tissue protein. (An analogy to this might be if one wanted to place the names of new movies on a marquee, but they were missing the letter “D” in their bucket of letters. Theywouldneedtogetadifferent bucket of letters that contained D’s.) In general, grains and legumes can be combined to provide the essential amino acids. This has become a rule of thumb for vegetarians: to eat both grain and legumes at meals. But vegetable sources of protein do not providethesamequantityofproteinas meat sources, so more food mass has to be consumed. Historically, the indiginous people of Central and South America harvested two vegetable crops that were very high in both quantity and quality of protein (that is, they were protein-rich and contained most of the essential amino acids.) They were spirulina, a bluegreenalgaescrapedoffthetopsoflakes, which contained all of the essential amino acids, and amaranth, a grain crop equally as important as maize and beans. Vitamins and minerals in our diets: Primary sources of vitamins and minerals include vegetables and fruits. Some students may be interested in why we need so many different vitamins and minerals-what each does for us, or what would happen if we had a deficiency of any one of them. You might ask them to do some library research on this; we have listed a description of the function of different vitamins and minerals in the appendix. Lesson 1 Food, Energy, and Growth TEACHER’S GUIDE TG65 Here’s another way of asking the same question about protein and meat, only about different people. We know that people in other cultures, including people in the United States with different cultural heritages, eat different types of food. What’s your sense of what people in other cultures eat? 3. Think for a minute about people in Mexico, for example. What picture do you have in your head about how average people in Mexico eat? How healthful would you think their diets are, in terms ofenougb carbohydrates for energy and enough proteins for growth? 3. Students typically have misconceptions about the diets and quality of life of people in other cultures. Take a look at a typical diet for people living in different places around theworld: Mexico - Corn Tortillas and dried beans Southern United States - Rice and black-eyed peas United States - Peanut butter and bread China - Rice and bean curd Japan - Fish India - Rice and lentils Italy - Spaghetti and cheese Eskimo - Seal or whale meat Tuareg Tribe of the Sahara - Millet and lentils 4. Healthy vegetarian diets must both grains and legumes in order to obtain all the amino acids needed for growth and repair. In addition, everyone needs plenty of fresh fruits and vegetables in order to obtain the needed vitamins and minerals. You may want to pose the following questions to students as they are developing an understanding of how other culture’s diets are nutritious: 4. Using your chart of the components of various foods, and your understanding of how vegetarians get the different amino acids they need, determine the “healthfulness” of the typical menu of several different cultures. 1. Are the protein sources complete or complementary? 5. Are you surprised by what you have discovered? 2. If the proteins are complementary, what food is from the legume family and what is from the: grain family? 3. What is wrong with a diet that consists mainly of rice or cereal? 4. Why are baked or refried beans sometimes served instead of meat? 5. Suggest three other combinations of vegetables that would provide a balanced diet. *** Actually, the peoples who lived in the Western Hemisphere before Europeans arrived made important contributions to the variety of healthful foods available to the world. Corn, potatoes, peppers all originated here, and were carried back to Europe. Native American cultures (north and south) sustained their people on very healthful and diverse diets, although they did not include much meat, 66 Michigan Department of Education 5. Answers vary. sl Lesson 15 TG 66 Michigan Department of Education because of the difficulty or expense of obtaining it. Their healthful diets were constructed from the foods that they cultivated in their own special climates. Those diets form the basis of today’s meals throughout the Americas, including familiesin the U. S. with cultural ties to Mexico, Central and South America, and the Caribbean. And what we have been discovering holds equally true for cultures that originated in Africa, the Middle East, and Asia. All around the world people have established for themselves healthful, sustaining, and diverse diete based on what they can grow and catch. These diets were the results of agricultural technology and experimentation in every culture. These diets may be somewhat different from yours, or you may have ties to one of these highly successful cultures in which many diverse, nutritious, and tasty foods originated. Food is a part of everyone’s cultural heritage. Enjoy! Food, Energy, Growth 67 El Lesson 15 Food, Energy, and Growth TEACHER’S GUIDE TG 67 All living things need food. Food supplies the energy needed for life activities (moving, breathing, sensing, growing, reproducing), and the materials needed for growth and repair. Unit Content Summary Animals, including humans, have always relied on plant parts for food (see the K-4 unit, “Running on Energy.“) Green plants are unique in being able to manufacture new food, by capturing energy from the sun and storing it in sugar molecules (glucose> made from carbon dioxide and water. These sugar molecules are built up into the various structures of plants (leaves, stems, roots, seeds, fruits, flowers, and so on), eventually becoming all of the different types of food that all living things use (see the 5 7 unit, “The Lives of Plants.“) Animals, then, spend most of their lives undoing the work of plants: Converting sugar molecules into carbon dioxide and water, releasing the energy stored in sugar to use in the conduct of their lives; and breaking apart the parts of plants in order to build up again the parts they need for their own bodies. How animals do this (especially how humans do this) is the subject of this unit. It starts with digestion. Energy is a very difficult concept forstudentstounderstand. They know that it is needed to survive but seldom can explain how it is obtained. Even adults are sometimes naive about energy when they think that it comes from exercising. Digestion And it starts in the mouth. Food (which in general is made up of carbohydrates, fats, and proteins-see the product labeling on any food package-as well as small amounts of vitamins and minerals) is first physically broken into smaller pieces, and then mixed with saliva, which contains an enzyme that chemically changes some of the carbohydrates (mostly starches) into simple sugars (including glucose.> Food then moves down the esophagus into the stomach where more enzymes mix with it as it is churned and turned. Some of those enzymes convert more carbohydrates into glucose; others begin to break down proteins into amino acids. Finally, food moves into the small intestine, traveling through 30 feet of it (in adult humans) while the process of digestion is completed. Continuing the digestion of carbohydrates and proteins, new enzymes begin to react with fats, breaking them down into fatty acids and glycerol. The new molecules produced by digestion-simple sugars, fatty acids, and amino acids-are water soluble. Food, Energy and Growth TEACHER’S GUIDE Appendix 1 Circulatory system Then the circulatory system takes over. Its function is to move these small, relatively simple molecules to all of the cells of the body. The digested materials leave the small intestine and enter the circulatory system through tiny openings or holes in the walls of the intestine and bloodvessels. Since these substances are water soluble, they can be absorbed by the blood and can move with it all over the body. (Undigested non-soluble food particles which could not get out of the small intestine move into the large intestine and finally out of the body as feces.) While many studentsknow that food is digested in our bodies, they often believe that it “gives up its energy” in the stomach. Theyoftendon’tunderstandthat it then moves out to all cells of the body, where it releases its chemical energy. And constantly, all over the body, the digested substances leave the blood stream and enter the cells. It is in the cells where all the really important action takes place: releasing energy for life activities; building new materials for growth and repair. All three substances-simple sugars, fatty acids, and amino acids-can be used to release energy, although it is primarily the simple sugars (which come from carbohydrates) that are used first. The fatty acids and amino acids (from fats and proteins) are the building blocks of new materials-the new materials that build longer bones, larger muscles, new skin, new blood as we grow and as we repair damaged and worn out body parts. Cellular How do cells release the energy of simple sugars? The cells of all respiration living things do this, from humans to mice to worms to amoebas, and not only animals, but all living things, including plants. Even plants use their own glucose as food, to release the energy they need for their life activities. Cellular respiration can generally be represented by the followingequation, although the actual process consists of a series of more complex chemical reactions: C,H,,O,+ 60,--9 6H,O + 6C0, + energy Students seldom relate the need for oxygen with energy production. Appendix 2 What goes on in cells is a series of complex chemical reactions that use oxygen (this is why we breathe!) to break down glucose into carbon dioxide and water, releasing the energy (originally from the sun) stored in the glucose (by plants.) Carbon dioxide and water are waste products that are removed from the cell and carried away by the circulatory system to the lungs-where the carbon dioxide and some water vapor are breathed out-and to the kidneys-where water is discarded in the urine. To illustrate this process of cellular respiration a bit more: During vigorous physical activity, the need for glucose and oxygen increases with the increased need for energy. When you’re exercising vigorously, you know that you have to breathe faster (to take in more oxygen), and-ifyou control how much you eat-the extra glucose you need will be converted from the fat Michigan Department of Education your body normally stores from excess food. Also during exercise, the production of water and carbon dioxide increases. The increased heart and breathing rate is the body’s way of delivering and removing these extra materials to and from the cells during this increased activity. Some of the energy released in cells is heat energy, which maintains your body temperature or heats you up when you exercise. But most of it (about 60%) remains as chemical energy, transferred to many special molecules (called ATP) in the cell, each of which can store the energy in very small usable quantities. These energy-rich ATP molecules move around the cell, supplying the energy needed by cells for life processes. The chemical energy in ATP molecules can be changed to motion in muscle cells, to light in the light-producing cells of the firefly, or to electrical signals in brain cells. It is used to move blood, repair wounds, move the lungs to breathe, and make new cells. When students have heard of respiration before, they usually think of it simply as breathing. Students easily associate the need for energy with motion or exercise but seldom associate it with other cellular processes. Now the next question is, what happens with food to help people Growth and repair grow and repair damaged tissues? Again, this happens at the cell (protein synthesis) level. We grow by adding new cells to our bodies, new muscle cells, new skin cells, new heart cells, new blood cells, new blood vessel cells, etc. etc. Where do these new cells come from? They are made out Students don’t usually recognize of the materials in food: the building blocks of fatty acids and that new body growth requires amino acids. new materials that have to come Fatty acids are the building blocks for new fats and oils, which primarily make up cell membranes. Amino acids (along with nitrates and other minerals) are used for making specific new proteins, different from the ones in the plant and animal materials we eat. Some of these proteins are used for the inside components of new cells-the structures that allow nerve cells, for example, to pass electrical signals, or that allow muscle cells to contract. Some are exported out of certain cells to play important roles in fighting off disease (antibodies), or to regulate the action of organs (hormones) by acting as messengers or message receptors between cells. Some are used for the material that makes up hair, nails and teeth. Also, perhaps most importantly, protein is used to make enzymes. Enzymes are all over the body, not just in the digestive tract. They are needed to make many chemical reactions occur in cells. from somewhere. In other words, they don’t apply any knowledge they may have of conservation ofmatterin thiscontext of eating and growing. The process of building new molecules is a critical function of cells. It uses the building blocks supplied by food, it requires Food, Energy and Growth TEACHER’S GUIDE Appendix 3 In spite of their importance in living systems, most students have never heard of enzymes except perhaps in the digestive system. Diet and nutrition energy from cellular respiration, and it is directed by instructions coded in the DNA. Our bodies are alive with internal activity, even when we sleep! So in order to grow and maintain a healthy body, humans must eat sufficient quantities of carbohydrates, proteins and fats (along with vitamins and minerals) to supply all of the materials needed for growth and repair as well as all of the body’s energy needs. This is why parents have always been concerned about their children’s diets, and why world health organizations are concerned about food supplies in developing countries. Nutritionists tell us that we don’t need as much protein as we once thought, but the types of protein we eat are important; that we need complex carbohydrates for long-lasting energy supplies; and that we need very little fat in our diets. In general, American diets include too many calories and too much fat (especially saturated fat), cholesterol, and salt, and too few complex carbohydrates and fiber. These diets are generally believed to be one reason for the large numbers of cases ofobesity, heart disease, stroke and cancer in Americans. However, the exact role of the diet in preventing some of these diseases is not well understood. While many Americans are replacing the traditional diet represented by hamburgers, french fries, and shakes, many diverse cultures both within the U.S. and around the world have traditionally had much more healthy diets. There are almost as many ways of meeting nutritional needs as there are cultures in the world. In most places, the food people eat is that which comes from their natural environment, rather than that which they import. This includes harvests from the land and the surrounding sea. Cultures all over the world, including those of which many students in the United States are decendents, have developed ingeneous ways of meeting their nutritional needs, including the need for sufficient carbohydrates for energy and sufficient and complementary proteins for the numerous amino acids needed for protein synthesis. Appendix 4 Michigan Department of Education Class Name Food, Energy and Growth lNSTRUCTIONs: Please answer these questions to the best of your ability, without asking anyone for help.Theresultsofthistestwill~beusedforyourgrade. Please be as complete in your answers as you can. The more you write the more we will know for revising this unit. Even ifyou think that you haven't covered what’s in an item, please write the best answer you can 0 1992 Michigan Dept of Education; developed by Edward Smith, Theron Blakeslee, & Joseph Vellanti 1. At the right below is the nutrition information from the label of a jar of peanut butter. Use the information in this chart to answer the following questions: a) What nutrient(s) (food components) do you think this peanut butter is high in? Nutrition Information Per Serving: Calories . . . . . . . . . . . . . . . . . . . . 170 Protein . . . . . . . . . . . . . . . . . . 9 grams Carbohydrate . . . . . . . . . 4 grams Fat. . . . . . . . . . . . . . . . . . . . . .15 grams b) Explain why you would not want to eat peanut butter sandwiches every day. 2. Your body needs energy for all of its activities. Where can it get this energy? a. from resting b. from food c. from exercise d. from vitamins (Circle as many choices as you want.) 1 3. Most teenagers are physically active and still growing. Identify three foods that could be part of healthy diet for a teenager. For each food, explain why that food would contribute to a healthy diet by identifying a food component (nutrient) that it provides and explaining why each food component is important in a teenager’s diet. Food Item . . provided, . vthem a. b. C. 4. Which of the following are products your body can use that are likely to result from the digestion of food. Circle your choices. You may circle more than one. fats sugars starches proteins complex carbohydrates simple sugars amino acids carbon dioxide fatty acids vitamins oxygen 5. When you eat a turkey and cheese sandwich for lunch, parts of the sandwich get digested over the next few hours. a) What happens to the sandwich as it gets digested? b) Why does the sandwich need to be digested? this question continued on next page 2 c) What materials result from the sandwich being digested? d) Where in your body are these digested food materials used? e) What happens to these digested food materials after they get to where they are needed? 6. After running for a few minutes, a person will breathe more rapidly than before. What benefit to your body is there in breathing faster when you are running? Explain as completely as you can. Make sure you talk about what your body does with the additional amount of oxygen the runner takes in. 7. Since the time you were five years old, you have probably grown quite a bit. For example, the muscles that move your fingers are longer and larger. Explain as completely as you can how the muscles that move your fingers came to be so much bigger, and what food has to do with this growing. 3 8. You have probably had a cut somewhere on your hands or feet. When the cut healed, it may have left a scar or there may be no sign left of the cut at all. a) Where does the new shin come from that covers over the cut? b) What is going on in the shin cells around the cut as the cut heals? c) What hinds of food components help your body to heal cuts in your shin? U 9. When you inhale your lungs take in oxygen from the air. The oxygen is then carried by your blood for use in your body. a) Where in your body is the oxygen needed/used? b) How is the oxygen used after it gets to where it is needed? 4 10. The air you breathe out contains more carbon dioxide (CO,) than the air you inhale. a) Where in your body does the new carbon dioxide come from? b) Where does the carbon in the new carbon dioxide come from? 11. Which of the following are needed by the cells in the muscles in your arm? energy Not needed_ needed_ Why needed? oxygen Not needed_ needed_ Why needed? carbon dioxide Not needed_ needed_ Why needed? 12. A healthy diet should contain at least 2 servings of meats, poultry, fish, dry beans, eggs or nuts each day. Suppose you were trying to convince a younger brother or sister to eat more of these foods. How would you explain to them the importance of these foods in their diet? b) If you said, as your answer to 12a, that you need to eat these foods to be big and strong, then explain how food helps you to be big and strong. 5 13. If someone eats a lot of food, he or she will gain weight, perhaps in the form of fat around the waist. How is it that sometimes eating food will add fat around your waist? (Write about fat cells if you can). 14. If you are standing on a scale to weigh yourself, and you take a brick out of your pocket and drop it on the ground, you would lose weight, right? When you exercise, you can also lose weight. What is it that leaves your body to make you lose weight when you exercise? b) Explain why exercise helps you lose weight. 6 U The Food Guide Pyramid A Guide to Daily Food Choices Fats, Oils & Sweets / USE SPARINGLY Milk, Yogurt & Cheese Group 2-3 SERVINGS Bread, Cereal, Rice & Pasta / Group . Sweets Group RecommendedAmounts: Concentrated sweets should be consumed sparingly preferably, no more than once a day. This is because thesesim@esugarsareusedupvefyqulcldybythe body while the complex carbohydrates from the grain group can be used for energy for several hours. count as one serving: 1 piece of ple or cake 1 large cookie or 2 smaller cookies 1 piece of Chocolate candy 1/4 of a candy bar Topplngs or jam. Jelly syrup. honey.etc. Non-diet softdrinks Honey or sugar-coated cereals Milk, Yogurt and Cheese Group Court as one serving: 1 cup milk or milk products such as yogurt, cottage cheese, Ice cream, etc. 1/2 ounces cheese Fats and Oils Recommended Amount: 30% or less of your total calories should come from fat with less than 10% from saturated fat which are mainly from animal products.. Thls means about 33 grams of fat for each 1000 calories consumed. Most 15 to l8 year old females require about 2300 calories/ day and most 15-18 year old males require about 3000 calories/day. Those who are physically very active will requlree more. Count grams as follows 1 tablespoon of butter, margarine, salad dresslng, mayonnaise=10 grams fat 1 small serving (3 oz.) beef or pork=12 grams fat 1 small serving (3 oz.) lean beef or poultry (without skin)=6 grams fat 1 egg yolk=5 grams fat 1 cup whole milk or whole milk product=8 grams fat l cup 2% milk or milk products=5 grams fat 1 cup 1% milk or milk products=3 grams fat 1 cup 1/2% milk or milk products=1 gram fat Vegetable Group Court as one servIng: 1 cup raw, leafy greens 1/2 cup of other vegetables Breads, Cereal, Rice, l nrf Pasta Group Court as one serving: 1 slice bread 1/2 bun. bagel or English muffln 1 ounce of dry. ready-made cereal lxrwd 1/2 cup cooked cereal, dry pasta Fruit Group Count as one serving 1 medium apple, orange or banana 1/2 cup of small of diced fruit 3/4 cup fruit juice Fats, Oils and Sweets Milk, Yogurt & Bread, Cereal, Rice & Pasta Group Meat, Poultry, Fish Dry Beans, Eggs & Ii-- FOOD COMPOSITION TA B L E II PROTE SERVING SIZE (OUNCES) CAL (9) APPLE, RAW, W/SKIN. 1 AVG 5.3 69 0.3 APRICOTS. DRIED 3.5 237 3.6 FOOD IN(g) APRICOTS, RAW AVOCADO, RAW, BANANA 3.5 BLUEBERRIES, RAW I 56 I 0.7 CANTALOUPE, RAW GRAPEFRUIT, RAW, 112 z--k-k- GRAPES W/SKIN. @36 ORANGE, RAW, PEELED PEACH, RAW PEAR, RAW W/SKIN 7.1 I 116 11.1 I 0.1 I 0 17.5 I 0.1 I 0 I 0.6 PINEAPPLE, RAW, 1 SLICE STRAWBERRIES, RAW R A W1 SLICE , ASPARAGUS, RAW, BOILED 2+-k--k BUTTERNUT SQUASH, BAKED fkk4-F CABBAGE, RAW CARROTS, RAW CAULIFLOWER. RAW CELERY, RAW CORN-ON-THE-COB, BOILED y-y-y GREEN BEANS, BOILED GREEN PEPPER, RAW 5.4 1.4 I 9 I 0.5 9.0 I 217 I I 0.2 I 0 0.3 0 HUBBARD SQUASH, BAKED LETTUCE, RAW U MUSHROOMS, RAW POTATO, BAKED W/SKIN 6.0 46.9 FOOD COMPOSITION TABLE CODFISH RAW BROILED SOURCES OF VITAMINS Vitamin A Egg yolks, butter, dark green and deep yellow vegetables, organ meats, fish liver oil. Vitamin B1 Seafood, poultry, meats, whole or enriched grains, green vegetables, milk, soy beans. Vitamin B2 Milk, eggs, poultry, yeast, meats, soy beans, dark green vegetables, mushrooms. Niacin Leafy vegetables, peanut butter, potatoes, whole or enriched grain, fish, poultry, meats, tomatoes. Vitamin B12 Green vegetables, liver, meat, fish, eggs, milk Vitamin C Citrus fruit, melon, strawberries, tomatoes, leafy vegetables. Vitamin D Milk, liver, eggs, fish liver oils. Vitamin E Vegetable oils, butter, milk, leafy vegetables, whole grain cereal. Vitamin K Green vegetables, tomatoes, soy bean oil, liver, cabbage, potatoes, peas. SOURCES OF MINERALS Calcium Milk and other dairy products, bean curd, dark green vegetables. Phosphorus Meats and dairy products, eggs. Sodium Meats, dairy products, salt. Chlorine Salt Potassium Orange juice, bananas, dried fruits, potatoes. Magnesium Nuts, grains, dark green vegetables, seafood, chocolate. Iodine Iron Seafood, iodized salt. Meats especially liver, dark green vegetables, dried fruits, whole grains SOURCES OF PROTEINS, FATS AND CARBOHYDRATES PROTEIN: The best sources of protein are from animal, parts. These are considered complete proteins because they contain all of the essential parts (amino acids) your body needs for building purposes. Examples of complete protein include meat, fish, poultry, eggs and dairy products (milk, cheese, yogurt, etc). Protein from plants usually contain protein in lesser amounts and it does not contain all of the essential building blocks (amino acids) for your body. These are called complementary proteins. Examples of plant protein are cereal grains (rice, corn, wheat, etc.) and legumes (most members of the bean, pea and nut families). FATS: Only a few foods such as margarine or butter contain only fat. Usually fats are found together with other nutrients. The fats are found in foods that come from both plants and animals. Animal sources that are high in fat content include red meat, pork, and whole milk or dairy products. Plant sources that are high in fat content include nuts, olives and seeds (sesame, sunflower, peanut, etc.) and the oils made from them which are used in cooking. Fish, poultry, eggs, skim milk dairy products, some starchy vegetables and fruits (corn, beans, peas, apples, etc.) have much smaller quantities of fat. STARCH: Foods that are high in starch content include grains (wheat, rice, corn, oats, etc.) starchy or non-watery vegetables (potatoes, winter squash, beets, beans, peas, etc.) and fruits (raisins, prunes, bananas, dates, figs, etc.) Foods that provide lesser amounts of starch are the watery vegetables (summer squash, lettuce, cabbage, cucumbers, etc.) and fruits (grapefruit, oranges, grapes, plums, etc.) SUGAR: Highest in sugar content are the concentrated sweets such as candy, honey, syrup, molasses, jam, jelly, and most non-diet soft drinks. Foods that contain lesser amounts of sugar are all fruits and vegetables. Edward Carlson Dewayne Anderson MSTA Western Michigan University Professor of Physics Michigan State University Richard Chase Boberta Jacobowitz Research Scientist Ford Motor Company Janet Kahan Science Teacher Lansing Otto Middle School Science Education Coordinator Midland Public School8 Barbara Mick Wendell Moyer Patricia Maldonado Peter Vunovich Dawn Pickard Hugo Pinti MEA Lansing Eastern High School Professor of Science Education Oakland University Greg Advisory Board Sarah Lindsey Elementary Science Specialist Ann Arbor Public School8 Principal Crawford AuSable (Grayling El.) School8 Michigan Science Education Resources Project Principal/MASSP Sturgis High School Outreach Director Battle Creek Area Math&i. Cntr Science Education Coordinator Flint Public School8 Zulauf Science Education Coordinator Muskegon Intermediate School Diet. Adelle Alim Detroit Publ. School8 Juanita Chambers Rose Arbanas Calhoun ISD Cherie Cornick Detroit Publ. School8 Wayne Co. M/S Alliance Bern. Ortiz De Montell Brenda Earhart Mary Edmond Evelyn Green Carmen Harris Mozell Lang Diana Marinez Fred Page Yvonne Peek Dawn Pickzrd Wayne State University Grand Rapids Public School8 Michigan State University Michigan State University Project Staff Joan Webkamigad Michigan Dept. of Education Kalamazoo Area Math/Sci. Ctr. Lansing Comm. College Michigan Dept. of Education Detroit Public School8 Oakland University Culturally-Relevant Advisory Committee State Board of Education, August, 1992 Dorothy Beardmore, President . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rochester Dr. Gumecindo Salas, Vice President . . . . . . ..__.__.......... East Lansing Michigan Science Education Resources Project Staff Writers Marilyn F. Lundy, Treasurer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Detroit Cherry H. Jacobus, NASBE Delegate . . . . . . . . . ...____........ Grand Rapids Theron Blakeslee Project Director Leona Bronstein East Lansing High School Deborah Nesbitt Roseville Junior High School Yvonne Peek Detroit Public Schools Elma Tuomisalo Ishpeming Joe Vellanti Lansing Eastern High School Katherine J. DeGrow w . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eaton Rapids Dick DeVos s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grand Rapids Barbara Roberts Mason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lansing Annetta Miller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Huntington Woods Ex Officio Members John Engler Governor Funded through a grant from the W. K. Kellogg Foundation Robert E. Schiller Superintendent of Public Instruction I- Consultants Howard Stein Grand Valley St. University Charles Anderson Michigan State University Edward Smith Michigan State University Pilot Teachers John Bjorkquist & Jeff Riffle Okemos High School Chris Johnson & Dave Kirschinger David McCloy Unionville-Sebewaing Mid. Sch. East Lansing High School Ted Falkenberg Diane Thiel Lincoln H.S. (Warren-Van Dyke P.S.) Port Hope Comm. Schools Advisory Board (See Inside Back Cover) Special thanks to Project assistant: Linda Vermeersch. Artwork: Ida Castillo and Tony Johnson. Cover artwork: Steve Light. Page layout: Tony Johnson. Editor: Sally Pratt. Thanks to the many workshop participants who offered constructive suggestions for revising this unit. Some of the material contained in this unit is derived from “The Power Cell Teacher’s Guide, ” a teaching unit authored by Charles W. Anderson, Kathleen J. Roth, Robert Hollon and Theron Blakeslec, and published by the Institute for Research on Teaching, Michigan State University, October, 1985. How to use the “Food, Energy and Growth” unit: (8th, 9th or 10th grade) l The student book: Each student should have a copy of the student book. This book includes reading, lab activities, and discussion questions, all integrated into lessons. The lessons are clustered into four sections (simply called “Clusters”), each based on a key question. l l l background information to help teachers see the broad directions and intent of the unit; lesson background and lab preparation (on blue sheets prior to each cluster) to prepare for the hands-on activities in each lesson; lesson statement, purpose, and approx. time for each lesson; margin notes on student thinking and content; answers to questions posed in the text; and a content summary (in the appendix) as background information on the content. Student journals: The student books have no space for writing answers to questions, so that they can be used by several classes. For writing answers, recording data from investigations, and posing new questions, we recommend that students use a journal. Journals have several advantages over single sheets of paper handed out and collected on a daily basis: They let students compile their work, as in a portfolio, gaining some sense of pride in their collection; and they allow students to look back on their early ideas, appreciating the way their understanding grows. Many different kinds of notebooks can be used as journals. In a few lessons, prepared handouts are available for students’ use (in the appendix), which can be kept in a pocket in their journal. Overhead transparency masters: The appendix contains three drawings of the human body, one showing the digestive system, one showing part of the circulatory system, and one showing the lungs. These three can be overlaid to illustrate discussions in the text. Annotated teacher’s edition of the student book: The teacher’s guide contains several pieces of information that should be helpful to teachers as they prepare and teach this unit. They include: Copyright 0 1992, by The State of Michigan. All Rights Reserved. Local and Intermediate School Districts in Michigan are encouraged to create copies for their own education purposes. l l Feel free to contact Mr. Theron Blakeslee, Project Director, at (517) 373-0454 with any questions or concerns.