BSCS Science: Unit 2 Overview

BSCS Science: An Inquiry Approach

Level 3

First edition, © 2010 by BSCS

Unit 2 Overview

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Energy and Matter: Shaping and Organizing Living Systems 3

Unit OverviewThe Energy and Matter: Shaping and Organizing Living

Systems unit focuses on energy transformations in the living world and the fundamental role of matter. These are the main enduring understandings that students should develop in this unit. Though there is an astonishing diversity of life-forms on Earth, all organisms are affected by fundamental laws concerning energy and matter. These principles affect individual organisms, but they also affect all levels of life (macromolecules, cells, organs, organ systems, individuals, species, communities, and ecosystems).

Students developed a working defi nition of energy in the Energy: Forms and Flow unit. They learned about various forms of energy, how it fl ows from one place to another, and that it is always conserved. A major focus was viewing energy from both a microscopic and macroscopic perspective. The life science unit builds on these understandings and applies concepts of energy to living systems.

The Engage activity for the unit, Compost Happens, makes the links to the physical science unit explicit. Chapter 1, Chemical Energy and Matter Matters, focuses on how all organisms use chemical reactions as a source of energy. Students examine cellular respiration, but focus on the trans-formations of energy that occur in the process, rather than on memorizing specifi c reactions. Students also examine how different living things are organized to obtain, transform, trans-port, and release the matter and energy they need. In chapter 2, Photosynthesis Rules!, students explore the powerful infl uence of photosynthesis on living systems at many levels. Again, the emphasis is on the energy transformations that take place. Students also consider how exchanges of energy and matter limit populations and cause interdependence among organ-isms. In chapter 3, Fueling the Future, students apply their understanding of the fl ow of energy and the cycling of matter to examine the formation, use, and impact of traditional fuels and alternative biofuels. Concepts learned in this unit will be helpful as students consider the fl ow of energy on Earth in the earth science unit, The Sun’s Energy, and are critical pieces to understanding global climate change in the science and society unit, A Climate of Change.

Before beginning Chapter 1, look ahead to the Engage activity for chapter 2. This activity requires radish seedlings that have been growing for at least 2 weeks. Read through this activity and plan accordingly.

Goals for the UnitBy the end of this unit, students will understand the following:

The conservation and transformation of energy and matter affect all levels of life.

Organisms break the chemical bonds of food molecules, forming different molecules with lower amounts of energy. As a result, energy is released.

Many organisms have specialized cells, tissues, organs, and organ systems to obtain and construct the molecules necessary for life.

Photosynthesis transforms light energy into chemical energy. This process has dramatic effects on all the levels of life.

Energy fl ows through ecosystems, and matter cycles.

The fl ow of energy and the cycling of matter can help inform current debates about the use of traditional and alternative biofuels.

All the units in Level 3 of BSCS Science: An Inquiry Approach reinforce specifi c, overarching themes. The themes are energy fl ow and energy transformation and the use of models, evidence, and explanations. In Energy and Matter: Shaping and Organizing Living Systems, students will investi-gate these concepts in three chapters.

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4 Energy and Matter: Shaping and Organizing Living Systems

Notes:


Strategies for the Unit Engage

Life Transformed!Activity Overview The goal of this unit Engage is to help students recognize that the energy transformations that they learn about in the physical sciences are crucial to life at all levels and occur in a variety of different ways in living organisms. This sets an important context for students as they begin to study the concepts in this unit.

Before You TeachBackground Information The following list of different forms of energy will be helpful for you in this activity:

Kinetic energy is the energy of motion. It includes the movement of substances, molecules, atoms, electrons, and waves. The following list explains the types of kinetic energy:

Electrical energy is made available by the fl ow of electric charges through a conductor. The movement of electric charges through a wire is called electricity.

Electromagnetic energy involves energy traveling in transverse waves. Light, X-rays, gamma rays, and radio waves are included in this category.

Heat, or thermal energy, involves the vibration and movement of the atoms and molecules within substances. It is a form of energy that fl ows between two samples of matter because of their difference in temperature.

Motion energy involves the movement of objects from one place to another.

Sound energy is the production of a series of waves involving compression and rarefaction caused by vibration in matter.

Potential energy is stored energy and energy of position. The following list gives examples of the types of potential energy:

Chemical energy is potential energy stored within chemical bonds.

Stored mechanical energy can be illustrated by a compressed spring. Energy is required to compress a spring and energy will be released when the spring releases.

Nuclear energy is the energy that holds the nucleus of an atom together. The combining or splitting of atoms does not take place in everyday events.

Gravitational energy is the energy of relative position or place.

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MaterialsFor the entire class1 transparency each of Electric Eel, Firefl y Mating Signal, Hibernating Animals, Brown Fat Cells, Vision, Protein Breakdown, Achilles Tendon, and Photosynthesis

For each student1 copy of copymaster 1.1, Energy Transformations in Living Systems Table

As You TeachOutcomes and Indicators of Success By the end of this activity, students should be able to identify different forms of energy and recognize that energy transforma-tions are necessary at every level of life’s organization. They will demonstrate their ability by

identifying different forms of energy and

completing a table about transformations of energy and identifying what level of biological organization is affected by the transformation.

StrategiesGetting Started Start with a brainstorming session about different types of energy and listing them on the board. It will be helpful to categorize the types of energy as forms of kinetic or potential energy. Refer to the list included in the background section if needed. If students are unfamiliar with many of the types of energy, you may need to devote more instructional time to helping them obtain a clearer understanding of energy. Energy transformations are the key to this unit. Keep the types of energy visible and then work with the class to establish the different levels at which life is organized (macromolecules, cells, organs, organ systems, individuals, species, communities, and ecosystems). Emphasize that each level of organization is highly organized and thus requires energy to remain complex. Also emphasize that each successive level of organization has emergent properties that result from interactions of numerous agents at the previous level.

Process and Procedure Hand out copies of copymaster 1.1, Energy Transformations in Living Systems Table, to students as they read through the instruc-tions for the unit Engage. Decide how you will have the students affi x the tables in their science notebooks. Use the following transparencies or animations to introduce each energy transfor-mation. After you introduce each event, ask the students to focus on the questions in the table: “Energy was in what form before the event?” and “Energy was in what form after the event?”

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Life Transformed!In this activity, you will record your ideas about some of the types of energy transformations in living systems. Learning about transformations of energy throughout life is the major learning goal for this unit.

MaterialsFor each student

1 Energy Transformations in Living Systems Table handout

Process and Procedure 1. Review the Energy Transformations in Living Systems Table handout

by yourself. Ask for clarifi cation if you do not understand the meaning of each column heading.

2. Identify the specifi c type of energy transformation in each interaction your teacher will show you. In what major form was the energy before the interaction? In what major form or forms was the energy after the interaction?

It’s OK if you don’t have the correct answer at this point. The goal is to chart your initial ideas about energy transformations in living things.

3. Identify the level or levels of biological organization that are affected by the energy transformation.

Different levels of biological organization include biomolecules, cells, organs, organ systems, individuals, species, communities, and ecosystems.

4. Fill in the empty cells in the table on your own after your teacher shows you each interaction.

5. Gather with 2 or 3 other students to form a team.

6. Your teacher will go through each interaction again. Work with your team to come to a consensus for the answer in each empty cell.

UNIT ENGAGE


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Show the Electric Eel transparency and then describe how the eel can discharge electricity and stun its prey. Show the Firefl y Mating Signal transparency and then describe how the fi refl y can glow. Show the Hibernating Animals transparency of the Richardson’s ground squirrel and discuss how this species hibernates. During hibernation, the squirrel’s body temperature drops to that of the surrounding soil. Next, show the Brown Fat Cells transparency and describe how these cells shrink in size as the animal warms itself back up to normal body temperature. Show the Vision transparency of the structure of an eye. Emphasize that light enters the eye, hits rod and cone cells in the retina, and then an electrical message is sent along the optic nerve.

Briefl y describe the fact that proteins break down into individual amino acids as you show the Protein Breakdown transparency. Show students the location of the Achilles tendon on the Achilles Tendon transparency and then have them hop up and down on 1 leg, if they feel comfortable doing so. While they are jumping, ask them to think about how their Achilles tendon is behaving like a spring. Ask them to think about the energy transformation that occurs when the tendon recoils after being stretched. Show the image on the Photosynthesis transparency. After individuals fi nish, have the students form small teams of 3–4 and go through the transformations again. Pay careful attention to what students say about the shrinking fat cells. If they

indicate that the cells shrunk because they were “turned into energy,” make sure you ask them to revisit this answer after they complete the Explain activity, Fueling Life. Matter turning into energy is a common misconception. Encourage the teams to come to a consensus on each cell. Students are likely to have diffi culty deciding what level of biological organi-zation is affected by the transformation. Reassure them that some transformations will affect multiple levels. They should be able to explain why they chose the level they did, however. After going through all the transformations again, lead the class in a discussion and start to fi ll in copymaster 1.1, Energy Transformations in Living Systems Table. Put a big question mark in cells that no one can answer or cells in which there is disagreement. Now is

Notes:


Reflect and ConnectWork individually as you answer these questions. Get feedback on your answers as your teacher directs.

1. You are complex and your body is highly organized. Maintaining this organization requires energy. What is the main source of energy for your body?

2. Which type of energy transformation do you think is the most important for determining the number of organisms in a biological community? Why?

3. The fi refl y converted chemical energy into light energy. Do you think that chemical energy can be completely converted to light energy with 100 percent effi ciency? Why or why not?


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not the time to give students the answers; instead, use students’ answers to assess their initial understanding of energy. As the unit proceeds, refer back to important questions as they are covered. For your reference, a table with sample answers is shown in fi gure TEn1.1.

Answers to Refl ect and Connect, SE page 7

1. Humans, like other consumers, need to transform chemical energy in order to stay complex and organized. Be open to a range of student responses at this point; transformation of energy is a major theme of the chapter. It will be useful for students to refl ect back on their initial answers later in the chapter.

2. With the exception of deep-sea vent communities, light is the ultimate source of energy for every ecosystem on Earth. Thus, the transformation of light energy into chemical energy is the most important for determin-ing the number of organisms in a community; this is a major theme of chapter 2. Again, be open to a range of student responses at this point. It will be useful for students to refl ect back on their initial answers later in the unit.

3. No transformations of energy are 100 percent effi cient, which is one way of stating the second law of thermodynamics. This idea will be continually emphasized throughout the unit. Students are asked to revisit

their answer to this question later in the unit, but if a number of students answer yes to this question, you may want to have them revisit their answer more frequently.

Notes:




Biological interaction

Energy transformed from

Energy transformed to

Levels of biological organization affected

What is the result of the transformation?

Shock from electric eel

Chemical Electrical Organ, individual, community (if students consider that the shock can stun prey)

Eel produces defensive or predatory shock.

Firefly mating signal

Chemical Light Organ, individual, population (signal is a mating call)

Firefly emits light to attract mates.

Brown fat cells shrinking during animal hibernation

Chemical Heat Biomolecules, cell, organism

Animal stays warm.

Light interacting in retina in an eye

Light Electrical and chemical

Organ, organism Presence of light is sent through nervous system.

Protein breakdown

Chemical Chemical Biomolecules Smaller packets of energy and building blocks can be rearranged.

Achilles tendon movement

Stored mechanical

Motion Individual Foot moves more efficiently.

Photosynthesis Light Chemical Biomolecules through ecosystems

Chemical energy is available to the cell, plant, and community.

Figure TEn.:Energy transformations in living systems table. Th is table shows possible student answers.


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BSCS Science: Unit 2 Overview