BSCS Biology: A Human Approach

Fourth edition, © 2011 by BSCS

Unit 3 Overview

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340 Unit 3 Energy, Matter, & Organization: Relationships in Living Systems

The diverse life-forms on Earth require energy and matter. Throughout unit 3, Energy,

Matter, and Organization: Relationships in Living Systems, students will learn how energy is related to matter and how energy and matter help organ-isms perform physically. To begin the unit, we engage the students’ interest in energy and matter, a sometimes abstract concept for students. Thus, in chapter 7, Physical Fitness and Perfor-mance, they will investigate how the use of matter and energy can help account for the various levels of human performance and fitness. In chapter 8, The Cellular Basis of Activity, the students will develop a greater depth of understanding by examining how cellular processes convert energy into matter, extract energy from matter (food), and support a variety of activities. In chapter 9, The Cycling of Matter and the Flow of Energy in Ecosys-tems, the students will develop greater breadth by learning how matter and energy link all the organisms in a community.

Prior ConceptionsThe focus of unit 3 on energy and matter in living systems is an area many students find challenging. It also is challenging for the teacher because the many incorrect prior conceptions are difficult to change. The BSCS 5E instructional model used throughout this program offers multiple oppor-tunities for teachers and students to recognize and compare these prior conceptions with biologically correct understandings.

The Project 2061 Atlas of Science Literacy identifies several incorrect prior conceptions related to matter and energy that high school students commonly have. While students are likely to understand, at least vaguely, that food provides energy for their activities, they are less likely to under-stand that food also is the source of

the molecules—or matter—they use for growth (American Association for the Advancement of Science [AAAS], 2001). The first Explain laboratory activity, What Is in the Food You Eat?, in chapter 7 will help students recog-nize that foods contain different types of molecules that their bodies use.

High school students tend not to recognize that the molecules in food must be transformed before they are incorporated into their bodies (AAAS, 2001). They are likely to believe that the protein in the food they consume is directly incorporated into their muscles, instead of understanding that proteins and other nutrients are broken down into subunits, which are then rebuilt into the specific proteins and other macromolecules that make

up their bodies. As students work through the second Explain activity in chapter 7 (You Are What You Eat), they will see how starch is broken down to glucose molecules. In part B of that activity (Food for the Body’s Building Blocks), they will view the video seg-ment, “Introduction to Biosynthesis,” which uses animations to show how macromolecules are built from the subunits that result from digestion.

Students may also think that food is the same thing as energy. Food con-tains energy-yielding nutrients (fats, carbohydrates, and proteins) that have potential energy in their chemical bonds. Organisms break the chemi-cal bonds of food molecules and form new bonds in different molecules that have lower energy, resulting in a

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Energy. We all need it in varying amounts, 24 hours a day, 365 days a year. What exactly is energy, and where does it come from? How

is energy related to the matter we take in each day as food? How do matter and energy help organisms like us perform? Think of a runner nearing the finish line. What is the source of energy the runner needs for that final burst of speed?

In unit 3, Energy, Matter, and Organization: Relationships in Living Systems, you will explore mat-ter, energy, and the relationship between them. You will investigate how concepts about matter and ener-gy can help explain how a runner can sprint to the

finish line at the end of a long race. Then you will see how cellular processes in the body transform energy from the food consumed by this runner. You will learn how the molecules in food affect the amount of energy you can derive from food. Before beginning chapter 9, The Cycling of Matter and the Flow of Energy in Ecosystems, you will construct exper-imental worm habitats and observe how the worms interact with their environments. Through the worm habitat activity and others in chapter 9, you will see how matter and energy link all of the organisms in a community.

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UNIT CONTENTS

7 Physical Fitness and Performance8 The Cellular Basis of Activity9 The Cycling of Matter and the Flow of

Energy in Ecosystems

87 9

3U N I T

341

Energy, Matter, & Organization:

Relationships in Living Systems

By the end of unit 3, you should be able to understand that

✔ human performance and physical fitness depend on diet and exercise;

✔ the conservation and transformation of energy and matter are found in all living systems;

✔ organisms release energy by breaking the chemical bonds of food molecules, forming different molecules that have lower amounts of energy;

✔ photosynthesis transforms light energy into chemical energy, with dramatic effects on all living systems;

✔ energy flows through ecosystems, and matter cycles in them; and

✔ well-designed investigations collect data, compare results to controls, draw conclusions, and report findings.

Unit 3 Energy, Matter, & Organization: Relationships in Living Systems 341

release of energy. Another common misconception is that matter in the form of food is converted directly into energy in everyday (non-nuclear) phenomena. Matter is conserved in the reactions of living organisms. The atoms in the molecules that make up the food that organisms eat are not destroyed and turned into energy. Rather, energy is released when the bonds between atoms in food mol-ecules are broken and new compounds with lower-energy bonds are formed. Activities in chapters 7 and 8 help students address these concepts.

A well-documented misunderstanding among high school students (as well as many adults) is that plants obtain food from the soil. It is difficult for students to replace this understanding with the correct conception that most of the biomass in plants is assembled from carbon dioxide (an invisible gas) from their environment. Plants use carbon dioxide, water, and energy from sunlight to make their own “food” internally (AAAS, 2001). You can help students by emphasizing this point as they complete the experiment in the chapter 8 Explain-Elaborate activity, Using Light Energy to Build Matter.

While high school students understand that dead organisms and waste products from organisms decay, they may not realize that decomposition requires the activity of other living organisms (AAAS, 2001). You can emphasize this point with your stu-dents when they examine their earth-worm habitats in the chapter 9 Explore activity, Matter Goes Round and Round, and when they complete the chapter 9 Elaborate activity, Generating Some Heat. Students are frequently uncertain about what happens to matter when it decays (AAAS, 2001). The experiment they design and carry out in Matter Goes Round and Round will help them follow the transformations of matter from one component of an ecosystem to another,

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340 340

Energy. We all need it in varying amounts, 24 hours a day, 365 days a year. What exactly is energy, and where does it come from? How

is energy related to the matter we take in each day as food? How do matter and energy help organisms like us perform? Think of a runner nearing the finish line. What is the source of energy the runner needs for that final burst of speed?

In unit 3, Energy, Matter, and Organization: Relationships in Living Systems, you will explore mat-ter, energy, and the relationship between them. You will investigate how concepts about matter and ener-gy can help explain how a runner can sprint to the

finish line at the end of a long race. Then you will see how cellular processes in the body transform energy from the food consumed by this runner. You will learn how the molecules in food affect the amount of energy you can derive from food. Before beginning chapter 9, The Cycling of Matter and the Flow of Energy in Ecosystems, you will construct exper-imental worm habitats and observe how the worms interact with their environments. Through the worm habitat activity and others in chapter 9, you will see how matter and energy link all of the organisms in a community.

LaurelTech/KH Design Pass First Pass Second Pass PDF Pass

UNIT CONTENTS

7 Physical Fitness and Performance8 The Cellular Basis of Activity9 The Cycling of Matter and the Flow of

Energy in Ecosystems

87 9

3U N I T

341

Energy, Matter, & Organization:

Relationships in Living Systems

By the end of unit 3, you should be able to understand that

✔ human performance and physical fitness depend on diet and exercise;

✔ the conservation and transformation of energy and matter are found in all living systems;

✔ organisms release energy by breaking the chemical bonds of food molecules, forming different molecules that have lower amounts of energy;

✔ photosynthesis transforms light energy into chemical energy, with dramatic effects on all living systems;

✔ energy flows through ecosystems, and matter cycles in them; and

✔ well-designed investigations collect data, compare results to controls, draw conclusions, and report findings.

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Unit Goals

341A Unit 3 Energy, Matter, & Organization: Relationships in Living Systems

helping to dispel the incorrect notion that matter is created and destroyed within each component.

Advance Preparation for the UnitFor the Explain-Elaborate activity, Using Light Energy to Build Matter, in chapter 8 and the Explore activity, Matter Goes Round and Round, in chapter 9, order the Anacharis (elodea) at the start of this unit so that there is time for the plants to adjust to your classroom environment. It may also be obtained from an aquatic specialty store. The Anacharis will perform best when grown in a warm aquarium with intense fluorescent lights and small fish or aquatic frogs that will not harm the plants. Matter Goes Round and Round in chapter 9 also uses snails, which should be ordered ahead of time. Do not place the snails in the same aquarium as the Anacharis, as they will eat it. Review the National Association of Biology Teacher’s Use

of Animals in Biology Education in the laboratory safety section of this guide.

You may also need to order materials for some of the other experiments in this unit. Check Materials and Prepara-tions for the chapter 7 activities, What Is in the Food You Eat? (first Explain), and, Structures and Functions (Elabo-rate), so that you can have the required materials available. In particular, note that indophenol and amylase should be purchased fresh each year.

As you begin this unit, set up (or have students take 1/2 to 1 class period to set up) the earthworm habitats for the Explore activity, Matter Goes Round and Round, in chapter 9. After setting up these habitats, plan to have stu-dents make brief observations of them once every several days as you move through chapters 7 and 8. Observations should span at least several weeks. See Preparations for that activity, on pages 481A-B, for detailed directions on how to set up the earthworm habitats and direct student observations.

Finally, as you generate your plans for the unit, review the Unit 3 Assessment. Plan time in

your classroom schedule for students to complete this assessment, and consider the setting in which you wish to have students engage in this final learning opportunity for the unit. For more information, consult the Guide to Assessment.

Check the Preparations for each chapter to locate the online activities in this unit. Reserve a

computer with access to the Web well in advance and preview the video segments before you have the students watch them in class. As you begin each chapter, look ahead to the specific strategies for each laboratory activity that calls for probe ware systems. Probe ware options occur in the Explain and Explain- Elaborate activities, Keep a Body Running! and Using Light Energy to Build Matter, in chapter 8, and the Explore activity, Matter Goes Round and Round, in chapter 9.

Notes