What is biology?

Unit OverviewUnit 1 includes one chapter thatintroduces students to the nature,excitement, and methods of biology. Chapter 1 Students are firstintroduced to the characteristicsof living organisms. The nature ofscience and methods used in sci-ence are then discussed withexamples intended to spark stu-dent interest as they attempt toanswer questions and solve prob-lems concerning the world of life.

Introducing the UnitAsk students to look at the photoand describe some of the adapta-tions of poppies that make themsuccessful. Tell students that theywill learn in this unit how to identify the characteristics of allliving organisms, including pop-pies. Explain to students that dur-ing their studies in this course, theywill use the methods of sciencedescribed later in the chapter.

A WebQuest is aninquiry-based online project inwhich all information used bystudents is obtained from theWeb. Students evaluate the infor-mation to complete the activity.Access the Unit 1 WebQuest at

Activity Have students select a sci-entist from the time line and preparea short biography on that person andhis or her accomplishments. Each stu-dent should give a presentation onthe person he or she selected. Have

the class combine their presentationmaterials to create one large postershowing each scientist’s contributionsto the field of biology. Display theposter in your classroom.

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What isbiology?What You’ll LearnChapter 1

Biology: The Study of Life

Unit 1 ReviewBioDigest & Standardized Test Practice

Why It’s ImportantBiologists seek answers to questions about living things.For example, a biologist might ask how plants, such asCalifornia poppies, convert sunlight into chemical energythat can be used by the plants to maintain life processes.Biologists use many methods to answer their questionsabout life. During this course, you will gain an under-standing of the questions and answers of biology, andhow the answers are learned.

105Tsai Lun inventspaper as weknow it today.

520 B.C.Greek philosophers proposethat the universe is composedof four elements: earth, air,fire, and water.

Understanding the PhotoThis field of flowers represents not only a collectionof living things, but also a community. These plantsinteract with each other, and form a biological com-munity that provides food, nesting materials, andoxygen for other living things.

400 B.C.Hippocratesfounds theprofession ofphysicians.

350 B.C.The first classificationof 500 species of ani-mals is created.

Hippocrates

ca.bdol.glencoe.com/webquest (t)Ed Eckstein/CORBIS, (crossover)Carr Clifton/Minden Pictures

The following standards are covered in Unit 1:Investigation and Experimentations: 1k, 1f, 1g

California Standards

ca.bdol.glencoe.com/webquest

Advance MaterialsPlanningThe following materials may needto be ordered a few weeks inadvance of the planned activity.

Chapter 1■ MiniLab (p. 6) mildew

samples■ Quick Demo (p. 7) Lithops

plants■ Activity (p. 7) squash seeds,

bubbles, bubble wand, freshfruit, cut flower

■ Additional Lab (p. 12)brewed coffee: caffeinated anddecaffeinated

■ MiniLab (p. 14) isopropyl(rubbing) alchohol, over-the-counter products: aftershavelotion, cough syrups, mouth-wash

■ Quick Demo (p. 21) pineneedles

■ MiniLab (p. 22) oatmealpackets with candy dinosaureggs

■ BioLab (pp. 24–25) pill bugs

Tape ProductionVisual-Spatial Have students use avideo camera to make a tape cata-loging and describing the livingthings in your area. Students maytape the same area through theseasons to show changes.

Make a ModelKinesthetic Students can make athree-dimensional model thatdepicts the kinds of living thingsfound in your area. Alternatively,students can model another area,such as a rain forest.

Field InvestigationVisual-Spatial Have student groupsstudy a local pond or stream tofind out what living organisms arepresent. Students may wish tomake drawings or take photos toillustrate their findings.

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1452Gutenberg invents moveabletype, allowing mass productionof printed materials.

1895 X rays are dis-covered andthe first X rayof the humanbody is taken.

2000The first draft ofthe HumanGenome Project,sequencing allhuman genes, iscompleted.

The first X ray

1687Isaac Newton pub-lishes Principia,which details the first scientific methods.

1863Lincoln delivers theGettysburg Address.

1627Francis Baconpublishes workurging that theexperimentalmethod shouldplay a key rolein the develop-ment of scien-tific theories.

Bettmann/CORBIS

Section Objectives National Science State/Local Advanced Lab andStandards Standards Demo Planning

1/2 session

1. Recognize some possible benefitsfrom studying biology.

2. Summarize the characteristics ofliving things.

1 session, 1/2 block

3. Compare different scientific methods.

4. Differentiate among hypothesis,theory, and principle.

1 session, 1 block

5. Compare and contrast quantitativeand qualitative information.

6. Explain why science and technolo-gy cannot solve all problems.

End of Chapter AssessmentStudent Edition

Study Guide, p. 27Content Assessment, pp. 28–29

UCP.2; A.1, A.2;C.1, C.3, C.4, C.5,C.6; E.1, E.2; F.3,F.4, F.6; G.1, G.2,G.3

UCP.2; A.1, A.2;B.2; C.6; E.2; G.1,G.2

UCP.2; A.1, A.2; C.6;E.1, E.2; F.3, F.4, F.6;G.1, G2

Investigation &Experimentation1a, 1d

Investigation &Experimentation1a, 1d, 1f, 1j, 1k

Investigation &Experimentation1d, 1g, 1j

Student Lab:MiniLab 1.1, p. 6: mildew samples, micro-scope, microscope slides, coverslipsInternet BioLab, p. 24: See materials below.

Teacher Demonstration:Quick Demo, p. 7: Lithops plant

Student Labs:MiniLab 1.2, p. 14: glass slide, safety gog-gles, water, alcohol, alcohol-testing chemicalProblem-Solving Lab 1.1, p. 16Additional Lab, p. 12: 2 small jars, graduatedcylinder, labels, caffeinated coffee, decaf-feinated coffee

Teacher Demonstrations:Quick Demo, p. 12: sugar cube, matchesQuick Demo, p. 15: scientific journals

Student Labs: Problem Solving Lab 1.2, p. 20MiniLab 1.3, p. 22: oatmeal with candydinosaur eggs, 2 containers, water

Teacher Demonstration:Quick Demo, p. 21: metric ruler, pine needles

Student Lab:Internet BioLab, p. 24: Armadillidium (pillbug), clock or watch, container, ruler,Internet connection, dull pencil, plastic soupbowls

Level 1 activitiesshould be appropriatefor students withlearning difficulties.

Level 2 activitiesshould be within theability range of all students.

Level 3 activitiesare designed forabove-average students.

ELL activitiesshould be within theability range ofEnglish LanguageLearners.

Cooperative Learningactivities are designedfor small group work.

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Interactive Chalkboard: Section 1.1 Presentation CD-ROMTeacherWorks™ CD-ROMGuided Reading Audio Summaries MP3

Interactive Chalkboard: Section 1.2 Presentation CD-ROMTeacherWorks™ CD-ROMGuided Reading Audio Summaries MP3

Interactive Chalkboard: Section 1.3 Presentation CD-ROMTeacherWorks™ CD-ROMGuided Reading Audio Summaries MP3Video Labs

Interactive Chalkboard: Chapter X AssessmentMindJogger Videoquizzes DVD/VHSExamView® Pro Test Bank CD-ROM TeacherWorks™ CD-ROM

2B

Reproducible Masters Technology

and Transparencies

Unit 1 FAST FILE ResourcesMiniLab Worksheet, p. 3BioLab Worksheet, pp. 9–10Reinforcement and Study Guide in English,

pp. 13–14Reinforcement and Study Guide in Spanish,

pp. 17–18Concept Mapping, p. 21Critical Thinking/Problem Solving, p. 22Transparency Worksheet, p. 23

Reading Essentials for Biology,Section 1.1

Section Focus Transparency 1

Unit 1 FAST FILE ResourcesMiniLab Worksheet, p. 5Real World BioApplications, pp. 11–12Reinforcement and Study Guide in English, p.15Reinforcement and Study Guide in Spanish, p. 19Transparency Worksheet, p. 24

Reading Essentials for Biology,Section 1.2

Laboratory Manual, pp. 1–4Section Focus Transparency 2

Unit 1 FAST FILE ResourcesMiniLab Worksheet, p. 7Reinforcement and Study Guide in English, p. 16Reinforcement and Study Guide in Spanish, p. 20Transparency Worksheet, p. 23

Reading Essentials for Biology,Section 1.3

Laboratory Manual, pp. 5–8Section Focus Transparency 3

Unit 1 FAST FILE ResourcesChapter Assessment, pp. 27–32Student Recording Sheet, p. 33

Reviewing Biology,pp. 1–2

Interactive Chalkboard CD-ROM: Section 1.1 PresentationTeacherWorks™ CD-ROMGuided Reading Audio Summaries MP3

Interactive Chalkboard CD-ROM: Section 1.2 PresentationTeacherWorks™ CD-ROMGuided Reading Audio Summaries MP3Virtual Lab CD-ROMVirtual Lab: Dependent and Independent Variables

Interactive Chalkboard CD-ROM: Section 1.3 PresentationTeacherWorks™ CD-ROMGuided Reading Audio Summaries MP3Virtual Lab CD-ROMVirtual Lab: Dependent and Independent Variables

Interactive Chalkboard: Chapter 1 AssessmentMindJogger Videoquizzes DVD/VHSExamView® Pro Test Bank CD-ROM TeacherWorks™ CD-ROM

Transparency CD-ROM MP3 Videocassette DVD

Legend

/self_check_quiz/vocabulary_puzzlemaker/chapter_test/standardized_test

Succeeding on National Standards CD-ROM

Indicates materials created specifically for California.

2B

ca.bdol.glencoe.com

Short on Time?

The BioDigest at theend of this unit can be used as a(n):• preview to introduce important

unit concepts.• overview if time does not per-

mit teaching the entire chapter.• review of key unit concepts.

Understandingthe PhotoUse the image to introduce thecharacteristics of life that all liv-ing things share. Be sure that thestudents understand that livingthings, such as moose and plants,have all of these characteristics,not just one or two of them.Additional information aboutthese characteristics is discussedin detail on pages 6–10.

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Demo To elicit students’ preconcep-tions about the nature of biology,arrange the following materials on adesk: a grasshopper or other livinginsect in a cage, a potted plant, a rock,a photo of a population of organisms.Ask students: What do you think you

will learn about during your study ofbiology? Guide students toward anunderstanding that, in addition toplants and animals, their study of biology will include a broad under-standing of all living things.

What You’ll Learn■ You will identify the charac-

teristics of life.■ You will recognize how scien-

tific methods are used tostudy living things.

Why It’s ImportantRecognizing life’s characteristicsand the methods used to studylife provides a basis for under-standing the living world.

Visit to• study the entire chapter

online• access Web Links for more

information and activities onbiology

• review content with theInteractive Tutor and self-check quizzes

Biology: The Study of Life

Biology: The Study of Life

Even though the moose andplants pictured here appear tobe completely different fromeach other, they share certaincharacteristics that make themboth living things. Animals and plants, as well as otherorganisms such as mushroomsand bacteria, all exhibit thebasic characteristics of life.

Understandingthe Photo

Roy Toft

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ca.bdol.glencoe.comThis CD-ROM is an editableMicrosoft® PowerPoint®

presentation that includes:• Section presentations• Section checks• Image bank• Hot links to Biology Online• All transparencies

3

BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 1,Section 1.1

What are some characteristics of living organisms?

Which of these characteristics does each object have?

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1 FocusBellringerSection Focus Transparency 1

Have the students find anddefine other words using “bio”as part of the root, such as biohazard and biotechnology.

FOLDABLES™For an additional Foldablesactivity idea, see the Chapter 1Foldables page in Unit 1 FAST

FILE Resources.

The Science of BiologyPeople have always been curious about living things—how many dif-

ferent kinds there are, where they live, what they are like, how they relateto each other, and how they behave. The concepts, principles, and theo-ries that allow people to understand the natural environment form thecore of biology, the study of life. What will you, as a young biologist,learn about in your study of biology?

A key aspect of biology is simply learning about the different types ofliving things around you. With all the facts in biology textbooks, youmight think that biologists have answered almost all the questions aboutlife. Of course, this is not true. There are undoubtedly many life formsyet to be discovered; many life forms haven’t even been named yet, letalone studied. Life on Earth includes not only the common organismsyou notice every day, but also distinctive life forms that have unusualbehaviors.

biology from theGreek words bios,meaning “life,”and logos, mean-ing “study”;Biology is thestudy of life.

1.1 WHAT IS BIOLOGY? 3

Characteristics Organism 1 Organism 3Organism 2

Make a Table As you read Chapter 1, list the characteristics of living things in the far left column. Choose three organisms that seem different from each other and make notes in each column describing how each organism fulfills the requirements of a living thing.

Characteristics of Living Things Make the following Foldable to help you organize information about the characteristics of living things.

Fold a vertical sheet of paperin half from top to bottom, twice.

Fold the paper widthwise into six sections.

Unfold, lay the paper length-wise, and draw lines along the folds.

Label your table as shown.

STEP 1

STEP 3

STEP 2

STEP 4

SECTION PREVIEWObjectivesRecognize some possiblebenefits from studyingbiology.Summarize the character-istics of living things.

New Vocabularybiologyorganismorganizationreproductionspeciesgrowthdevelopmentenvironmentstimulusresponsehomeostasisenergyadaptationevolution

1.1 What is biology?Standard 1k Students will recognize the cumulative nature of

scientific evidence.California Standards

Unit 1 FAST FILE ResourcesMiniLab Worksheet, p. 3BioLab Worksheet, pp. 9–10Reinforcement and Study Guide in

English, pp. 13–14Reinforcement and Study Guide in

Spanish, pp. 17–18

Concept Mapping, p. 21Critical Thinking/Problem Solving, p. 22Transparency Worksheet, p. 23

Reading Essentials for Biology,Section 1.1

Section Focus Transparency 1

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2 TeachVisual LearningFigure 1.1 Ask students to dis-cuss other uncommon organismsthey have read about or seen ontelevision. Explain that even withsuch diversity, all living thingshave certain characteristics incommon.

Concept DevelopmentVisual-Spatial Take studentsaround the school grounds. Askthem to list in their notebooks allthe different kinds of organismsthey observe. They should indi-cate the characteristics they usedto categorize each organism as aliving thing.

DisplayMake a bulletin board display thatshows unusual structural andbehavioral adaptations of plantsand animals.

Biology JournalInvestigating Newly DiscoveredLife Forms Ask students to findout about some of the most recentdiscoveries of new species. Askthem to report in their journalsabout how and where these organ-isms were discovered and who dis-covered them. Ask them to discussthe significance of each discovery.L3

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(tl)Steve Kaufman/DRK Photo (tr)John Gerlach/DRK Photo (bl)Norbert Wu/Mo Yung Productions (br)Jeffrey Lepore/Photo Researchers

When studying the different typesof living things, you’ll ask what, why,and how questions about life. Youmight ask, “Why does this livingthing possess these particular fea-tures? How do these features work?”The answers to such questions lead tothe development of general biologicalprinciples and rules. As strange assome forms of life may appear to be,there is order in the natural world.

Biologists study the interactions of life

One of the most general principlesin biology is that living things do notexist in isolation; they are all func-tioning parts in the delicate balance ofnature. As you can see in Figure 1.1,living things interact with their envi-ronment and depend upon other liv-ing and nonliving things to aid theirsurvival.

4 BIOLOGY: THE STUDY OF LIFE

Figure 1.1Questions about living things can sometimes be answered only byfinding out about their interactions with their surroundings.

The seahorse is well hidden in its environment. Itsbody shape blends in with the shapes of the seaweedsin which it lives.

C The spadefoot toad burrows underground duringextended periods of dry weather and encases itself in awaterproof envelope to prevent water loss.

D

Leaves of the insect-eating pitcher plant form a lip linedwith downward-pointing hairs that prevent insects fromescaping. Trapped insects fall into a pool of water anddigestive juices at the bottom of the tube.

BLeaf-cutter ants feed on fungus. They carry bits ofleaves to their nest, then chew the bits and formthem into moist balls on which the fungus grows.

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(t)Bob Daemmrich (b)William J. Weber/Visuals Unlimited

Biologists Study theDiversity of Life

Many people study biology simplyfor the pleasure of learning about theworld of living things. As you’ve seen,the natural world is filled with exam-ples of living things that can be amus-ing or amazing, and that challengeyour thinking. Through your study ofbiology, you will come to appreciatethe great diversity of life on Earth and the way all living organisms fitinto the dynamic pattern of life on ourplanet.

Biologists study the interactionsof the environment

Because no living things, includinghumans, exist in isolation, the studyof biology must include the investi-gation of living interactions. Forexample, learning about a populationof wild rabbits would require findingout what plants they eat and whatanimals prey on them. The study ofone living thing always involves thestudy of the others with which itinteracts.

Human existence, too, is closelyintertwined with the existence ofother organisms living on Earth.Plants and animals supply us withfood and with raw materials likewood, cotton, and oil. Plants alsoreplenish the essential oxygen in theair. The students in Figure 1.2 arestudying organisms that live in a localstream. Activities like this help pro-vide a thorough understanding of liv-ing things and the intricate web ofnature. It is only through such knowl-edge that humans can expect tounderstand how to preserve the healthof our planet.

Explain why scientists study an organism’s environment.

Biologists study problems and propose solutions

The future of biology holds manyexciting promises. Biological researchcan lead to advances in medical treat-ment and disease prevention inhumans and in other organisms. Itcan reveal ways to help preserveorganisms that are in danger of disap-pearing, and solve other problems,like the one described in Figure 1.3.The study of biology will teach youhow humans function and how we fitin with the rest of the natural world.It will also equip you with the knowl-edge you need to help sustain thisplanet’s web of life.

1.1 WHAT IS BIOLOGY? 5

Figure 1.2By understanding theinteractions of livingthings, you will be bet-ter able to impact theplanet positively.

Figure 1.3Honeybees and manyother insects are impor-tant to farmers becausethey pollinate the flowersof crop plants, such asfruit trees. In the 1990s,populations of many pol-linators declined, raisingworries about reducedcrop yields.

Students often think that allorganisms found in an areaare native to that area.

Uncover theMisconceptionAsk students to describe dif-ferences between an organ-ism that is native to an areaand one that is not. Explainthat non-native organismsmay be well adapted, lessadapted, or may have beenintroduced without the limi-tations they had in theirnative area.

Demonstrate theConceptExplain cases of introducedspecies, such as the redimported fire ant, whichcame from South America inthe 1930s and has steadilyspread from Alabamathroughout the southernportions of the U.S. Theseants are aggressive and havecaused extensive damage toagriculture and wildlife instates such as Texas.

Assess NewKnowledgeAsk students to suggest howthey might find out if a partic-ular plant is native to a givenarea. Introduced species ofteneither die out soon or thepopulation rapidly increasesat the expense of native pop-ulations because of a lack ofenvironmental controls.

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Scientistsstudy an organism’s environ-ment because the existenceof living things is alwaysdependent on the environ-ment and other living thingsin the environment.

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Purpose Students will look at mildewunder the microscope in a well-ventilated room and decide if it isliving. CAUTION: Allergic stu-dents may observe mildew sealedin the plastic bag and use slidesthat are already prepared.

Process Skillspredict, compare and contrast,observe and infer

Safety PrecautionsHave students turn to p. 1107 foran introduction to the safety sym-bols used in this text.

TroubleshootingScrape mildew samples fromshower grout or plastic showercurtains and bring them to class.Store samples in water to preventthem from drying out. CAUTION:If live specimens are used, sealthem in a plastic bag to protectstudents who might be allergic tomildew spores or whose asthmamight be triggered by mildew.

Teaching Strategies■ Prior to the activity, ask how

many students think mildew isliving/not living. Post theresults on the chalkboard. Pollstudents again after theMiniLab.

■ Preserved mildew from biolog-ical supply houses can be usedin place of live specimens.

■ Instruct students on use ofmicroscope and microscopeslides.

■ Demonstrate the technique formaking a wet mount. Includeproper handling and cleaningof cover glasses and glass slides.

Expected ResultsStudents may initially predict thatmildew is not alive. Duringmicroscopic examination, stu-dents will see long filaments(hyphae) and tiny circular objects(spores). Some students may seespores enclosed in a spore sac.

(t)John Sohlden/Visuals Unlimited (b)Kjell B. Sandved/Photo Researchers

Characteristics of Living Things

Most people feel confident thatthey can tell the difference between aliving thing and a nonliving thing,but sometimes it’s not so easy. Inidentifying life, you might ask, “Doesit move? Does it grow? Does it repro-duce?” These are all excellent ques-tions, but consider a flame. A flamecan move, it can grow, and it can pro-duce more flames. Are flames alive?

Biologists have formulated a list ofcharacteristics by which we can recog-nize living things. Sometimes, nonliv-ing things have one or more of life’scharacteristics, but only when some-thing has all of them can it then beconsidered living. Anything that pos-sesses all of the characteristics of life isknown as an organism, like the plantsshown in Figure 1.4. All living things• have an orderly structure• produce offspring• grow and develop• adjust to changes in the

environmentPractice identifying the characteris-tics of life by carrying out theMiniLab on this page.

6 BIOLOGY: THE STUDY OF LIFE

Data Table

Prediction Life Characteristics

First None

Second

Third

Figure 1.4These plants are called Lithops from theGreek lithos, meaning “stone.” Althoughthey don’t appear to be so, Lithops are justas alive as elephants. Both species possess allof the characteristics of life.

Mildew

ObservePredicting Whether Mildew Is Alive What is mildew? Is it alive? We see it “growing” on plastic shower curtains or on bathroom grout. Does it show the character-istics associated with living things?

Procedure! Copy the data table below.

@ Predict whether or not mildew is alive. Record your prediction in the data table under “First Prediction.”

# Obtain a sample of mildew from your teacher. Examine it for life characteristics. Make a second prediction andrecord it in the data table along with any observed lifecharacteristics. CAUTION: Wash hands thoroughly afterhandling the mildew sample. Do not handle the sample ifyou are allergic to mildew.

$ Following your teacher’s directions, prepare a wet mountof mildew for viewing under the microscope. CAUTION:Use caution when working with a microscope, microscopeslides, and coverslips.

% Are there any life characteristics visible through the microscope that you could not see before? Make a thirdprediction and include any observed life characteristics.

Analysis 1. Describe Which life characteristics did you observe?2. Interpret Data Compare your three predictions and

explain how your observations may have changed them.3. Observe and Infer Explain the value of using scientific

tools to extend your powers of observation.

Analysis1. organization, reproduction, growth,

adjusting to environment2. Answers will vary, depending on the

observations made by individual students.3. Certain life characteristics could not

have been seen without the use of amicroscope.

Modified AssessmentKnowledge Have students compose a list ofthings that are questionable as to whether theitems listed are living things or not. As aclass, go through the list and discuss whethereach thing should be considered alive or not.L1

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Living things are organizedWhen biologists search for signs of

life, one of the first things they lookfor is structure. That’s because theyknow that all living things show anorderly structure, or organization.

The living world is filled withorganisms. All of them, including theearthworm pictured in Figure 1.5,are composed of one or more cells.Each cell contains the genetic mate-rial, or DNA, that provides all theinformation needed to control theorganism’s life processes.

Although living things are verydiverse—there may be five to ten mil-lion species, perhaps more—they areunified in having cellular organiza-tion. Whether an organism is madeup of one cell or billions of cells, all ofits parts function together in anorderly, living system.

Living things make more living things

One of the most obvious of all thecharacteristics of life is reproduction,the production of offspring. The litter of mice in Figure 1.6 is just

one example. Organisms don’t liveforever. For life to continue, theymust replace themselves.

Reproduction is not essential forthe survival of an individual organism,but it is essential for the continuationof the organism’s species (SPEE sheez).A species is a group of organisms thatcan interbreed and produce fertileoffspring in nature. If individuals in aspecies never reproduced, it wouldmean an end to that species’ existenceon Earth.

Figure 1.5Like all organisms, earth-worms are made up ofcells. The cells form struc-tures that carry out essen-tial functions, such asfeeding or digestion. Theinteraction of these struc-tures and their functionsresult in a single, orderly,living organism.

Figure 1.6A variety of mechanismsfor reproduction haveevolved that ensure thecontinuation of eachspecies. Some organisms,including mice, producemany offspring in onelifetime.

(t)O.S.F./Animals Animals (b)Tom McHugh/Photo Researchers

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Living CharacteristicsShow students a Lithopsplant and ask how theymight determine whether it is living or nonliving. L2

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ActivityKinesthetic Give small groups ofstudents the following materials: asquash seed, a bottle of bubblesand a bubble wand, a fresh fruitsuch as a tomato, a cut flower in atest tube filled with water, and awarming candle in a jar lid. Lightthe candle for each group andinstruct students to observe theflame. CAUTION: Take extremecare with fire around the students.

Instruct them to blow a fewbubbles. Ask them to observe eachof the other objects. Have studentsdecide whether or not each item isalive and explain the reasons fortheir decisions. Discuss responsesas a class. You may find it necessaryto distinguish between nonlivingthings and once-living or deadthings as part of the discussion.Students will probably knowthat bubbles and warming can-dles are not alive, but becausethey move, students may saythey are alive.

Microscope ActivityVisual-Spatial Have studentsrefer to the Skill Handbook toreview the proper procedures forcaring for and using a micro-scope. Then ask them to examineprepared slides of a variety oforganisms. L2

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Alive or Not Set up stations aroundthe classroom with living and non-living items such as a rock withlichens, a bird’s nest, a potted plant,seeds, and other interesting materi-al you may have. Ask students todecide if each item is alive or notand to justify their answers. L3

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Pages 6–7: Inv. & Exp. 1a, 1d

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DiscussionLead students in a discussion ofgeneral developmental stages ofvarious organisms. Examplesinclude complete and incompletemetamorphosis in insects, orbirth, infancy, childhood, puberty,adulthood, old age, and death inhumans.

Career PathCourses in high school: biology,speech, language arts, history, andcomputer skillsCollege: a degree in biology,forestry, education, or a relatedfield preferred

Career IssueNature interpreters and othersinvolved in protecting the envi-ronment recognize the conflictbetween the needs of humans andthose of plants, animals, and othernonhuman organisms.

For More InformationMany people are needed in a vol-unteer capacity at local parks andnative preserves. Ask students toresearch and find what educationalprograms are offered by nearbynature preserves and the scienceeducation background and experi-ence of the interpreter who worksthere. The National Park Serviceemploys more than 20 000 peoplenationwide and relies on the addi-tional services of nearly 100 000volunteers.

(t)Tom Bean/DRK Photo (b)John Gerlach/DRK Photo

Living things change during their lives

An organism’s life begins as a singlecell, and over time, it grows and takeson the characteristics of its species.Growth results in an increase in theamount of living material and the for-mation of new structures.

All organisms grow, with differentparts of the organism growing at dif-ferent rates. Organisms made up ofonly one cell may change little duringtheir lives, but they do grow. On theother hand, organisms made up ofnumerous cells go through manychanges during their lifetimes, such asthe changes that will take place in theyoung nestlings shown in Figure 1.7.Think about some of the structuralchanges your body has already under-gone since you were born. All of thechanges that take place during the lifeof an organism are known as itsdevelopment.

Living things adjust to their surroundings

Organisms live in a constantinterface with their surroundings, orenvironment, which includes theair, water, weather, temperature, anyother organisms in the area, andmany other factors. For example,the fox in Figure 1.8 feeds on small

8 BIOLOGY: THE STUDY OF LIFE

Figure 1.7All life begins as a single cell.As cells multiply, each organ-ism grows and develops andbegins to take on the charac-teristics that identify it as amember of a particular species,such as the owls shown here.

Nature PreserveInterpreter

I f you like people as much as youlove nature, you can combine

your skills and interests in a careeras a nature preserve interpreter.

Skills for the JobInterpreters are also called nat-

uralists, ecologists, and environmental educators. Theymight work for a nature preserve or a state or nationalpark, where they give talks, conduct tours, offer video pre-sentations, and teach special programs. Some interpretersare required to have a degree in biology, botany, zoology,forestry, environmental science, education, or a related field.They must also be skilled in communicating with others.

Many interpreters begin as volunteers who have nodegrees, just a love for what they do. Over time, volun-teers may become interns and eventually be hired.Interpreters often help restore natural habitats and protectexisting ones. Part of their job is to make sure visitors donot harm these habitats and to point out the wonders ofthese natural areas.

For example, many tidepool organisms find protectionfrom too much sunlight by crawling under rocks. A natural-ist can explain the importance of replacing rocks exactly asthey were found.

For more careers in related fields, visitca.bdol.glencoe.com/careers

The History of Biological Discovery:Interpersonal Have students work ingroups of three or four to prepare apresentation about the history of bio-logical science in a different country.Student presentations can include achronology of discoveries in the coun-try, or they can be more specific

accounts of a particular area ofresearch. Presentations should includenames of scientists, details about theresearch, and how the research mayhave benefited society. Encourage stu-dents to incorporate posters, models,photographs, or videos in their presen-tations.

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The BioLab at the end of thechapter can beused at thispoint in the lesson.

Caption Question AnswerFigure 1.8 Bears hibernate whenair temperatures drop and foodbecomes unavailable; butter-flies metamorphose from cater-pillars to pupae at a time whenleafy food may become scarce;and resurrection plants openand close their leaves depend-ing on water availability.Students may list many others.Make certain that studentsunderstand that these changesare part of the organisms’ adap-tations. These activities are notconscious decisions on the partof the organism.

PortfolioStimulus and Response Havestudents cut five pictures frommagazines that show organismsresponding to stimuli. Ask stu-dents to mount each picture on aclean sheet of paper and label thestimulus and response. Have stu-dents place their labeled illustra-tions in their portfolios.

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(l)John Gerlach/DRK Photo (r)Tom Brakefield/DRK Photo

animals such as rabbits and mice.The fox responds to the presence ofa rabbit by quietly moving toward it,then pouncing. Trees adjust to cold,dry winter weather by losing theirleaves. Anything in an organism’sexternal or internal environmentthat causes the organism to react is astimulus. A reaction to a stimulus isa response.

The ability to respond to stimuli inthe environment is an importantcharacteristic of living things. It’s oneof the more obvious ones, as well.That’s because many of the structuresand behaviors that you see in organ-isms enable them to adjust to theenvironment. Try the BioLab at theend of this chapter to find out moreabout how organisms respond toenvironmental stimuli.

Regulation of an organism’s inter-nal environment to maintain condi-tions suitable for its survival is calledhomeostasis (hoh mee oh STAY sus).Homeostasis is a characteristic of lifebecause it is a process that occurs in allliving things. Living things also useinternal feedback to respond to inter-nal changes. For example, organismsmust make constant adjustments to

maintain the correct amount of waterand minerals in their cells and theproper internal temperature. Withoutthis ability to adjust to internalchanges, organisms die.

Living things reproduce them-selves, grow and develop, respond toexternal stimuli, and maintain home-ostasis by using energy. Energy is theability to cause change. Organismsget their energy from food. Plantsmake their own food, whereas ani-mals, fungi, and other organisms gettheir food from plants or from organ-isms that consume plants.

Living things adapt and evolveAny inherited structure, behavior, or

internal process that enables an organ-ism to respond to environmental factorsand live to produce offspring is calledan adaptation (a dap TAY shun).

Adaptations are inherited from previous generations. There are alwayssome differences in the adaptations of individuals within any population of organisms. As the environmentchanges, some adaptations are moresuited to the new conditions than others. Individuals with more suit-able adaptations are more likely to

1.1 WHAT IS BIOLOGY? 9

Figure 1.8Living things respond to stimuli and makeadjustments to environmental conditions.

Trees that drop their leaves in the fall conserve water andavoid freezing during winter.

A

Keen senses of smell and hearing enable a fox to find prey. Furallows foxes and othermammals to regulatebody temperature.Describe What aresome other examplesof how feedback mechanisms help maintain homeostasis?

B

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1. for the pleasure of learning about living things, or to appreciate the diver-sity of species and the way each fits intothe dynamic patterns of life on Earth

2. A stimulus is anything in the environ-ment that requires an organism toadjust. The adjustment made is theresponse. Sweating in humans is a

response to the stimulus of high temperature.

3. Energy is required for organisms to carryon all life processes. Organisms, such asplants, obtain energy from sunlight, butmost organisms obtain their energy byconsuming living or dead organisms.

4. Biology research expands understand-ing of how the natural world works

and aids development of helpful tech-nology.

5. A transfer of energy is often necessaryto maintain homeostasis.

6. Examine its organization and see if it is cellular or not; see if it grows ordevelops; see if it responds to stimulior adapts to a change in its environ-ment; see if it maintains homeostasis.

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(l)Sam Fried/Photo Researchers (r)Renee Lynn/Photo Researchers

survive and reproduce. As a result,individuals with these adaptationsbecome more numerous in the popula-tion. Figure 1.9 shows some examplesof adaptation.

The gradual change in a speciesthrough adaptations over time isevolution (e vuh LEW shun). Cluesto the way the present diversity oflife came about may be understoodthrough the study of evolution. You

will study how the theory of evolutioncan help answer many of the questionspeople have about living things.

As you learn more about Earth’sorganisms in this book, reflect on thegeneral characteristics of life. Ratherthan simply memorizing facts aboutorganisms or the vocabulary terms,try to see how these facts and vocabu-lary are related to the characteristicsof living things.

Understanding Main Ideas1. What are some important reasons for studying

biology?

2. Identify and describe how an organism couldrespond to an external stimulus. Describe aresponse to an internal stimulus.

3. Why is energy required for living things? How do living things obtain energy?

4. Describe how biologists’ research contributes toour understanding of the world.

Thinking Critically5. Describe how energy and homeostasis are related

in living organisms.

6. Observe and Infer Suppose you discover anunidentified object on your way home fromschool. What characteristics would you study todetermine whether the object is a living or nonliv-ing thing? For more help, refer to Observe andInfer in the Skill Handbook.

SKILL REVIEWSKILL REVIEW

10 BIOLOGY: THE STUDY OF LIFE

Figure 1.9Living things adapt to their environments in a variety of ways.

The desert Ocotillo has leaves onlyduring the rainy season. Lacking leavesduring the dry season is an adaptationwhich helps conserve water.

A

Manynocturnalanimals, suchas this owl,possess largeeyes forefficient visionat night.

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ca.bdol.glencoe.com/self_check_quiz

Check for Understanding Have students explain how ahome heating system models ahomeostatic mechanism.

ReteachHave students draw a dia-gram to illustrate how thepupil of the eye responds tobright light. Students canobserve this homeostaticmechanism in the classroomusing flashlights or lamps.CAUTION: Make sure stu-dents do not shine lightsdirectly into their eyes.

ResourcesFor more practice, useReading Essentials forBiology, Section 1.1.

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ExtensionAsk students working in groups toinvestigate the latest develop-ments in robotics. Have them listthe characteristics of robots andcompare and contrast these char-acteristics with those of livingorganisms. Have them point outkey characteristics that distin-guish robots as nonliving.

Skill Ask students to explain howthey would test to see which colorof light would cause a bean plantto grow faster. L2

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BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 1,Section 1.2

What is being tested in this experiment?

How could you improve the experimental setup?

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Unit 1 FAST FILE ResourcesMiniLab Worksheet, p. 5Real World BioApplications, pp. 11–12Reinforcement and Study Guide in

English, p.15Reinforcement and Study Guide in

Spanish, p. 19

Transparency Worksheet, p. 24Reading Essentials for Biology,

Section 1.2Laboratory Manual, pp. 1–4Section Focus Transparency 2

1 FocusBellringerSection Focus Transparency 2

Using an AnalogyExperiment Encourage studentsto develop a controlled experi-ment that they might carry out byhaving them do research, make atestable hypothesis, define a con-trol group, an independent vari-able, and a dependent variable. Ifpractical, students may carry outtheir experiment.

M.C. Chamberlain/DRK Photo

1.2 THE METHODS OF BIOLOGY 11

The Methods of Biology1.2

Observing and HypothesizingCuriosity is often what motivates biologists to try to answer simple

questions about everyday observations, such as why earthworms leavetheir burrows after it rains. Earthworms obtain oxygen through theirskin, and will drown in waterlogged soil. Sometimes, answers to questionslike these also provide better understanding of general biological princi-ples and may even lead to practical applications, such as the discovery thata certain plant can be used as a medicine. The knowledge obtained whenscientists answer one question often generates other questions or provesuseful in solving other problems.

The methods biologists useTo answer questions, biologists may use many different approaches, yet

there are some steps that are common to all approaches. The commonsteps that biologists and other scientists use to gather information andanswer questions are collectively known as scientific methods.

Scientific methods do not suggest a rigid approach to investigating and solving problems. There are no fixed steps to follow, yet scientific

SECTION PREVIEWObjectivesCompare different scien-tific methods.Differentiate amonghypothesis, theory, andprinciple.

Review Vocabularyenvironment: an organism’s

surroundings (p. 8)

New Vocabularyscientific methodshypothesisexperimentcontrolindependent variabledependent variablesafety symboldatatheory

Why does rain bring out the worms?Using an Analogy Have you noticedthat moss grows only in shady, moistlocations? Or that earthworms crawl tothe surface after a rain? If you have everwondered why moss grows in certainlocations, or why earthworms appearafter a rain, then you have used methodslike scientists use to develop experi-ments. You might examine locationssuch as the one in the photo and makenotes on the environment in whichmoss grows. Scientists use many differ-ent methods to answer questions, but allscientific inquiries share some commonmethods.Experiment As you read the section, useyour new knowledge of scientific methods toplan an investigative procedure to learn whymoss grows only in shady, moist locations.

Mosses are tiny plants that grow indense clumps.

Standard 1f Students will distinguish between hypothesis andtheory as scientific terms.

California Standards

2 TeachBrainstormingAsk students to brainstorm a listof questions they have that relateto biology. Write the questions asa list on the board. Allow studentsto give examples of how theymight find answers to their ques-tions if they were given access toany equipment or technologythey can imagine. L2

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Conducting an Experiment

Purpose Students will follow scientific methods tosolve a problem. The question to beanswered is: Does caffeine in coffee pre-vent mold growth?

PreparationSome students may be allergic to moldspores or have an asthmatic reaction.Have students wash their hands with soapafter working with mold.

Materials2 small jars (baby food jars), graduatedcylinder, labels, caffeinated coffee, decaf-feinated coffee

ProcedureGive the following directions to students.1. Form and record a hypothesis.2. Write your name and the date on the

labels. Write #1 on one label and #2 onthe other. Place the labels on the jars.

3. Add the following to each jar. Jar 1: 30 mL caffeinated coffee; Jar 2: 30 mL decaffeinated coffee. Identify a control.

Gerry Ellis/ENP Images

hypothesis fromthe Greek wordshypo, meaning“under,” and thesis, meaning a “placing”; Ahypothesis is atestable explana-tion of a naturalphenomenon.

Figure 1.10Brown tree snakes(Boiga irregularis) wereintroduced to Guammore than 50 yearsago. Since then, theirnumbers have increaseddramatically, and theyhave severely reducedthe native bird popula-tion of the island.

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investigations generally involve mak-ing observations and collecting rele-vant information as well as using logicalreasoning and imagination to makepredictions and form explanations.Scientific methods usually begin withscientists identifying a problem to solveby observing the world around them.

The question of brown tree snakes

Have you ever been told that youhave excellent powers of observa-tion? This is one trait that isrequired of biologists. The story ofthe brown tree snake in Figure 1.10serves as an example. During the1940s, this species of snake was acci-dentally introduced to the island ofGuam from the Admiralty Islands inthe Pacific Ocean. In 1965, it wasreported in a local newspaper thatthe snake might be considered bene-ficial to the island because it is apredator that feeds on rats, mice,and other small rodents. Rodents areoften considered pests because theycarry disease and contaminate foodsupplies.

Shortly after reading the newspaperreport, a young biologist walkingthrough the forests of Guam made an

important observation. She notedthat there were no bird

songs echoing throughthe forest. Looking

into the trees, shesaw a brown

tree snake

hanging from a branch. After learningthat the bird population of Guam haddeclined rapidly since the introduc-tion of the snake, she hypothesizedthat the snake might be eating thebirds. A hypothesis (hi PAHTH us sus)is an explanation for a question or aproblem that can be formally tested.Hypothesizing is one of the methodsmost frequently used by scientists. Ascientist who forms a hypothesis mustbe certain that it can be tested. Untilthen, he or she may propose sugges-tions to explain observations.

As you can see from the brown treesnake example, a hypothesis is not arandom guess. Before a scientistmakes a hypothesis, he or she hasdeveloped some idea of what theanswer to a question might be throughpersonal observations, extensive read-ing, or previous investigations.

After stating a hypothesis, a scien-tist may continue to make observa-tions and form additional hypothesesto account for the collected data.Eventually, the scientist may test ahypothesis by conducting an experi-ment. The results of the experimentwill help the scientist draw a conclu-sion about whether or not thehypothesis is correct.

ExperimentingPeople do not always use the word

experiment in their daily lives in thesame way scientists use it in theirwork. As an example, you may haveheard someone say that he or she wasgoing to experiment with a cookierecipe. Perhaps the person is plan-ning to substitute raisins for choco-late chips, use margarine instead ofbutter, add cocoa powder, reduce theamount of sugar, and bake the cook-ies for a longer time. This is not anexperiment in the scientific sensebecause there is no way to know what

Hypothesize Try to set asugar cube on fire using alighted match. It does notburn. Rub the edge of thecube in ashes and attemptto ignite it. It burns. Ask stu-dents to use what theyknow about combustion toform a hypothesis aboutwhy the cube burns after itis rubbed in ashes. Responsesmay include that the ashes—not the sugar cube—burn,that the ashes served as kin-dling, or that the ashes cat-alyze, or speed up, the reac-tion between the sugar andthe oxygen in air (burning).Ask students how theymight test their explana-tions. Responses mightinclude trying to set theashes on fire separately orexposing the sugar to a hot-ter flame for a longer time.

Caption Question AnswerFigure 1.11 (p. 13) The amountof fertilizer is the independentvariable.

4. Place both jars, uncovered, in the samelocation.

5. Make daily observations of your jars forone week. Check for the presence ofmold.

6. Record your observations in a suitabledata table by making diagrams of thecoffee liquid surfaces.

Analysis 1. Which type of coffee allows mold to

grow? both2. Was your hypothesis supported by your

data? will depend on hypothesis3. What was the control, independent

variable, and dependent variable?decaffeinated coffee, caffeinated cof-fee, mold growth

AssessmentPortfolio Have students write a reportof their experimental findings. Ask themto record any other questions that aroseduring this experiment and explain howthey might be answered. Use thePerformance Task Assessment List forLab Report in PASC, p. 119. L2

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(t)The Ohio State University/OARDC (b)Tom Brakefield/DRK Photo

effect any one of the changes alonehas on the resulting cookies. To a sci-entist, an experiment is an investiga-tion that tests a hypothesis by theprocess of collecting informationunder controlled conditions.

What is a controlled experiment? Some experiments involve two

groups: the control group and theexperimental group. A control is thepart of an experiment that is thestandard against which results arecompared. The control receives noexperimental treatment. The experi-mental group is the test group thatreceives experimental treatment.

Suppose you wanted to learn howfertilizer affects the growth of differ-ent varieties of soybean plants. Yourhypothesis might state that the pres-ence of fertilizer will increase thegrowth rate of each plant variety. Anexperimental setup designed to testthis hypothesis is shown in Figure1.11. Fertilizer is present in the soilof the experimental plants, but notthe controls. All other conditions—including soil, light, and water—arethe same for both groups of plants.

Designing an experimentIn a controlled experiment, only

one condition is changed at a time.The condition in an experiment thatis tested is the independent vari-able, because it is the only factor thataffects the outcome of the experi-ment. In the case of the soybeans, the presence of fertilizer is the inde-pendent variable. While testing theindependent variable, the scientistobserves or measures a second condi-tion that results from the change.This condition is the dependentvariable, because any changes in itdepend on changes made to the inde-pendent variable. In the soybeanexperiment, the dependent variable

is the growth rate of the plants.Controlled experiments are mostoften used in laboratory settings.

However, not all investigations arecontrolled. Suppose you were on agroup of islands in the Pacific that isthe only nesting area for a large sea-bird known as a waved albatross,shown in Figure 1.12. Watching thenesting birds, you observe that thefemale leaves the nest when her mateflies back from a foraging trip. Thebirds take turns sitting on the eggs orcaring for the chicks, often for twoweeks at a time. You might hypothe-size that the birds fly around theisland, or that they fly to some distantlocation, in search of food. To testthese hypotheses, you might attach asatellite transmitter to some of thebirds and record their travels.

Figure 1.12The waved albatross isa large bird that nestsmainly on Hood Islandin the GalápagosIslands. By tagging thebirds with satellitetransmitters, scientistshave learned wherethese birds travel.

Figure 1.11This experiment testedthe effect of fertilizeron the growth of sev-eral varieties of soy-beans. For eachexperiment there arethree rows of each variety. The center rows are the experi-mental plants. Theouter rows are the controls. Infer What isthe independentvariable in thisexperiment?

1.2 THE METHODS OF BIOLOGY 13

CD-ROM Have students experi-ment with plants by altering conditions in Dependent andIndependent Variables.

Visual LearningFigure 1.12 Ask students to ex-plain how a satellite transmitter isuseful in tracking waved alba-trosses. Because albatrosses flylong distances over open ocean,a transmitter is useful because itcan continuously relay informa-tion that would be difficult orimpossible to attain in any otherway.

Tying to PriorKnowledgeLogical-Mathematical Presentthe following hypothesis to yourstudents: “Yeast, in its dry state,appears lifeless. If yeast producescarbon dioxide and is made up ofcells, then it is alive.” Ask studentsto: (a) Describe experimental pro-cedures that would need to be usedto verify this hypothesis. Giveyeast a source of food and waterand watch to see if it producescarbon dioxide. Then look at itunder the microscope to see if itis made up of cells. (b) Describereasoning that was used to form thehypothesis. Organisms that aremade up of cells and produce car-bon dioxide are described asbeing alive. If yeast meets theserequirements, then it is also alive.

Pages 12–13: Inv. & Exp. 1f, 1j

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Purpose Students will experiment todetermine which products con-tain alcohol.

Process Skillsdraw a conclusion, experiment,interpret data, observe and infer

Safety PrecautionsSee Safety Symbol chart on p. 1107. Review safety precautionsregarding goggles, hand washing,and the use of an acid solution.

Teaching Strategies■ For preparation instructions

for the alcohol-testing reagent,see page 17T.

■ Label three separate slides A, B,and C. Make one circle on eachslide with a China marking oreyebrow pencil. (Students coulduse small test tubes rather thanglass slides.) Use caution whencleaning glassware.

■ For circle C, use isopropyl(rubbing) alcohol. Products tobe tested may include after-shave lotion, cough syrups,mouthwash.

Expected ResultsStudent data will vary with theproducts tested. Circle A willappear yellow-orange, circle Bgreen to blue, and circle C yellow.

Analysis1. to determine which colors

indicate the presence orabsence of alcohol

2. Answers will depend onproducts tested.

AssessmentPerformance Provide studentswith several different typesof alcohol (rubbing, ethyl, meth-yl), and ask them to determinewhich types the alcohol-testingchemical can detect. Use thePerformance Task AssessmentList for Carrying Out a Strategyand Collecting Data in PASC, p. 97.

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An investigation such as this, whichhas no control, is the type of biolog-ical investigation most often used infieldwork.

The design of the procedure that isselected depends on what other inves-tigators have done and what informa-tion the biologist hopes to gain.Sometimes, a biologist will design asecond investigation even while a firstone is being conducted, to answer thequestion. Try your hand at investiga-tion in the MiniLab on this page.

Describe the rolesof a control, independent variable,and dependent variable.

Using toolsTo carry out investigations, scien-

tists need tools that enable them torecord information. The growth rateof plants and the information fromsatellite transmitters placed on alba-trosses are examples of important infor-mation gained from investigations.

Biologists use a variety of tools toobtain information in an investigation.Common tools include beakers, testtubes, hot plates, petri dishes, ther-mometers, balances, metric rulers, andgraduated cylinders. More complextools include microscopes, centrifuges,radiation detectors, spectrophotome-ters, DNA analyzers, and gas chro-matographs. Figure 1.13 shows somecomplex tools.

Maintaining safety Safety is another important factor

that scientists consider when carryingout investigations. Biologists try tominimize hazards to themselves, thepeople working around them, and theorganisms they are studying.

In the investigations in this text-book, you will be alerted to possiblesafety hazards by the safety symbolsshown in Table 1.1 and precautions.

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14 BIOLOGY: THE STUDY OF LIFE

InvestigateTesting for Alcohol Promotional claims for certain over-the-counter prod-ucts may not tell you that one of theingredients is alcohol. How can youverify whether or not a certain productcontains alcohol? One way is to simplyrely on the information provided on aproduct label or an advertisement.Another way is to investigate and findout for yourself.

Procedure

! Copy the data table.@ Draw three circles on a glass slide. Label them A, B, and C.

CAUTION: Put on safety goggles. # Add one drop of water to circle A, one drop of alcohol to

circle B, and one drop of alcohol-testing chemical to circlesA, B, and C. CAUTION: Rinse immediately with water iftesting chemical gets on skin or clothing.

$ Wait 2–3 minutes. Note in the data table the color of eachliquid and the presence or absence of alcohol.

% Record the name of the first product to be tested.^ Draw a circle on a clean glass slide. Add one drop of the

product to the circle.& Add a drop of the alcohol-testing chemical to the circle.

Wait 2–3 minutes. Record the color of the liquid.* Repeat steps 5–7 for each product to be tested. CAUTION:

Wash your hands with soap and water immediately afterusing the alcohol-testing chemical.

( Complete the last column of the data table. If alcohol is present, the liquid turns green, deep green, or blue. A yellow or orange color means no alcohol is present.

Analysis1. Infer Explain the purpose of using the alcohol-testing

chemical with water, with a known alcohol, and by itself.2. Evaluate Which products did contain alcohol? No alcohol?

Data Table

Color of Liquid Alcohol Present

Circle A

Circle B

Circle C

Product name

Product name

The control providesa comparison for the experimentalgroup. The independent variable isthe single condition that is changedin the experiment, and the depen-dent variable is the condition that is measured as a result of the change.

Learning Disabled: InterpersonalHave students plan scientific methodsto alter a cookie recipe, such asreplacing chocolate chips with nuts.Ask students to name the control tobe used, the independent variable,and the dependent variable.

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A safety symbol is a symbol thatwarns you about a danger that mayexist from chemicals, electricity, heat,or procedures you will use. Refer to thesafety symbols at the back of this bookbefore beginning any field investiga-tion or lab activity in this text. It is yourresponsibility to maintain the highestsafety standards to protect yourself aswell as your classmates.

Data gatheringTo answer their questions about

scientific problems, scientists seekinformation from their investigations.Information obtained from investiga-tions is called data. Sometimes, thesedata are referred to as experimentalresults.

Often, data are in numerical form,such as the distance covered in an alba-tross’s trip or the height that soybeanplants grow per day. Numerical datamay be measurements of time, temper-ature, length, mass, area, volume, orother factors. Numerical data may alsobe counts, such as the number of beesthat visit a flower per day or the num-ber of wheat seeds that germinate atdifferent soil temperatures.

Sometimes data are expressed inverbal form, using words to describe

observations madeduring an investiga-tion. Scientists who firstobserved the behavior of pandas inChina obtained data by recordingwhat these animals do in their natu-ral habitat and how they respond totheir environment. Learning thatpandas are solitary animals withlarge territories helped scientistsunderstand how to provide bettercare for them in zoos and researchcenters.

Having the data from an investiga-tion does not end the scientificprocess. See how data collectionrelates to other important aspects ofresearch on pages 1060–1061 in theFocus On.

(t)Robert Essel, NYC/CORBIS (b)Gerard Mare/Petit Format/Photo Researchers

1.2 THE METHODS OF BIOLOGY 15

Figure 1.13Biologists use many tools in their studies.

The opticalmicroscopemakes smalldetails visible.

B

Gel electrophoresis can be used to produce aDNA fingerprint as shown. Comparing DNAreveals how closely related two species are.

A

Table 1.1 Safety Symbols

Sharp Object Safety This symbol appears when a danger of cuts or punctures caused by the use of sharp objects exists.

Clothing Protection Safety This symbol appears whensubstances used could stain or burn clothing.

Eye Safety This symbol appears when a danger to the eyesexists. Safety goggles should be worn when this symbol appears.

Chemical Safety This symbol appears when chemicals used can cause burns or are poisonous if absorbed through the skin.

Science Journals Bringcopies of scientific journalsto class and allow studentsto examine them. Ask stu-dents to speculate as towhich branch of scienceeach journal addresses.(Other science magazines,available on newsstands,explain science in morecommon terms, but are notscience journals.)

BrainstormingA student repeats an investigationseveral times and each timerecords different data. Have stu-dents offer possible reasons whyan experiment might yield differ-ent data for different trials.Reasons include failure to keepall factors but one the same,errors in data recording, errorsin mathematical treatment ofthe data, or naturally occurringvariability in experimental out-come.

InquiryActivity Call all students’ atten-tion to Table 1.1, the SafetySymbols. Shown here are some ofthe most commonly used symbolsin this program. Students shouldalways wear an apron and safetygoggles and wash their handsthoroughly after handling labora-tory materials. Have students turnto page 1107 and study each ofthe symbols shown. Then havethem look through the text forexamples of these symbols. L1

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Hearing Impaired: Interpersonal Supplystudents with the following data show-ing how many seeds were germinatedby three laboratory groups over a three-day period. Group A had two seeds ger-minate on day 1, four seeds on day 2,and four seeds on day 3. Group B had

one seed germinate on day 1, six on day2, and five on day 3. Group C had twoseeds germinate on day 1, four on day2, and three on day 3. Have studentswork in groups to prepare a class graphof the number of seeds germinatingeach day for all three groups. L2

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PurposeStudents will analyze the claimsmade in a commercial.

Process Skillsanalyze information, draw a con-clusion, experiment, think critically

Teaching StrategiesYou may wish to have the entireclass analyze the same commercial.Tape a specific commercial andplay it back to the class. Or providestudents with the printed dialoguefrom a radio commercial.

Thinking Critically1. Student answers will vary.

Many commercials makeclaims without specifying anyscientific backing.

2. Student answers will vary.Many commercials appear touse inference. However,according to the Federal Food,Drug, and Cosmetic Act of1938, drugs must be safe andeffective for their intendeduse. According to the FederalTrade Commission Act, adver-tisers of products used nation-wide must be able to back uptheir claims with evidence andmust not be deceptive.

3. Students should describe a hypothesis, control, depen-dent and independent vari-ables, trials, data accumu-lation, and a conclusionbased on data.

AssessmentPortfolio Ask students to designa video commercial that bases itsclaims on experimental data.Have them include their data andanalyses as part of the commer-cial. Use the Performance TaskAssessment List for Video inPASC, p. 153. L2

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Thinking about what happened Often, the thinking that goes into

analyzing data takes the greatestamount of a scientist’s time. Aftercareful review of the results, the sci-entist must come to a conclusion:Was the hypothesis supported by thedata? Was it not supported? Are moredata needed? Data from an investiga-tion may be considered confirmedonly if repeating that investigationseveral times yields similar results. Toreview how scientific methods areused in investigations, see Figure 1.14on the next page.

After analyzing the data, scientistsoften have more questions than theyhad before the investigation. Theycompare their results and conclusionswith the results of other studies byresearching the published literaturefor more information. They alsobegin to think of other experimentsthey might carry out. Are all theclaims you hear on TV commercialsbased on data gathered by scientificmethods? Find out by conducting theProblem-Solving Lab here.

Reporting results Results and conclusions of investi-

gations are reported in scientific jour-nals, where they are available forexamination by other scientists.Hundreds of scientific journals arepublished weekly or monthly. In fact,scientists usually spend a large part oftheir time reading journal articles tokeep up with new information as it isreported. The amount of informationpublished every day in scientific jour-nals is more than any single scientistcould read. Fortunately, scientists alsohave access to computer databasesthat contain summaries of scientificarticles, both old and new.

Verifying resultsData and conclusions are shared

with other scientists for an importantreason. After results of an investiga-tion have been published, other scien-tists can try to verify the results byrepeating the procedure. If theyobtain similar results, there is evenmore support for the hypothesis.When a hypothesis is supported bydata from additional investigations, itis considered valid and is generallyaccepted by the scientific community.When a scientist publishes the resultsof his or her investigation, other sci-entists can relate their own work tothe published data.

16 BIOLOGY: THE STUDY OF LIFE

Analyze InformationAre promotional claims valid?”Our product is new and improved.” “Use this mouthwash and your mouth will feel clean all day.” Sound familiar? TV and radio commercialsconstantly tell us how great certain products are. Are these claims always based on facts?

Solve the ProblemListen to or view a commercial for a product that addresses a medical problem such as heartburn, allergies, or bad breath. If possible, tape the commercial so that you can replay it as often asneeded. Record the following information:1. What is the major claim made in the commercial?2. Is the claim based on experimentation?3. What data, if any, are used to support the claim?

Thinking Critically1. Evaluate In general, was the promotional claim based

on scientific methods? Explain your answer.2. Evaluate In general, are promotional claims made in

advertisements based on experimental evidence? Explainyour answer.

3. Experiment Plan an investigative procedure that could beconducted to establish promotional claims made for the product in your advertisement.

Recognizing Technology: Visual-Spatial Ask students to work in co-operative groups to prepare a timeline that shows the technologicaladvances in one area of biology, such as genetics, biotechnology, oroceanography.

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Purpose Students will review methodsused in scientific investigations.

Teaching Strategies■ Point out that not every scien-

tific investigation uses everymethod, nor do all investiga-tions lead to a published theory.

■ Provide students with biologi-cal journals, such as Science andNature. Ask them to look at thearticles and identify the meth-ods of science used. See paren-thetical comment in QuickDemo, p. 15.

Visual Learning■ Have students look at cork

cells through a microscope andcompare them with the photoon this page, then ask them tocompare the capabilities oftheir microscopes with the oneused by Robert Hooke.

■ For more help with usingmicroscopes, refer to the SkillHandbook.

Critical ThinkingOther scientists repeat the sameexperiment to validate originalresults. Scientists extend under-standing by performing experi-ments to answer related ques-tions.

InquiryActivity Have students work ingroups on a biological problemthey perceive in your area. At theconclusion of the project, studentsshould be able to explain the meth-ods of science they used.

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Scientific MethodsFigure 1.14Scientific methods are used by scientists to answer questions and solveproblems. The development of the cell theory, one of the most usefultheories in biological science, illustrates how the methods of science work.In 1665, Robert Hooke first observed cells in cork. He made the drawing onthe right, showing what he saw. Critical Thinking What is the function ofother scientists in the scientific process?

Observing The first step toward scientific discovery often takes placewhen a scientist observes something no one has noticed before. After Hooke’sdiscovery, other scientists observed cells in a variety of organisms.

Making a hypothesis A hypothesis is a testable explanation or answer to a ques-tion. In 1824, René Dutrochet hypothesized that cells are the basic unit of life.

Collecting data Investigations and experiments test a hypothesis. Data must be thor-oughly analyzed to determine whether the hypothesis was supported or disproved. Fromthe results, a conclusion can be formed. Over the years, scientists who used microscopes toexamine organisms found that cells are always present.

Publishing results Results of an investigation are useful only if they are made avail-able to other scientists for a peer review. Many scientists published their observations ofcells in the scientific literature. Scientists will analyze the procedure, examine the evidence,identify faulty reasoning, point out statements that go beyond the evidence, and suggestalternative explanations for the same observations.

Forming a theory A theory is a hypothesis that is supported by a large bodyof scientific evidence. By 1839, many scientific observations supported thehypothesis that cells are fundamental to life.The hypothesis became a theory.

Developing new hypotheses Anew theory may prompt scientists toask new questions or form additionalhypotheses. In 1833, Robert Brownhypothesized that the nucleus is animportant control center of the cell.

Revising the theoryTheories are revised as newinformation is gathered. Thecell theory gave biologists astart for exploring the basicstructure and function ofall life. Important discover-ies, including the discov-ery of DNA, have resulted.

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Cork cells as drawnby Robert Hooke

Quantitative Data: Linguistic Havestudents review articles on biologi-cal research in Scientific American,Science News, Newsweek, or localnewspapers. Ask students to write ashort essay identifying the methodsof science that were used. L3

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1. Students might hypothesize that beesprefer yellow flowers to purple flow-ers or that bees prefer flowers withmore abundant nectar.

2. Set up an experimental chamber.Within a specific amount of time, countand record how many ants move tobutter placed a specific distance from

the ants. Repeat several times. Repeatusing honey in place of the butter.

3. A hypothesis is a testable explanationfor a question. A theory is a refinedexplanation supported by extensiveexperimentation.

4. A control provides greater certaintythat observed results are not due tochance or other variables.

5. Prepare one batch of cookies using aknown recipe and another batch, theexperimental group, by varying a sin-gle item such as amount of sugar.

6. A new, revised hypothesis is tested, orthe experiment may be changed.Theories are supported by the results ofextensive experiments and observations.

18

Gregory G. Dimijian/Photo Researchers

For example, biologists studyingthe behavior of elephants in Africapublished their observations. Otherscientists, who were studying ele-phant communication, used that datato help determine which of the ele-phants’ behaviors are related to com-munication. Further investigationsshowed that female elephants emitcertain sounds in order to attractmates, and that some of the sounds

produced by bull elephants warnother males away from receptivefemales, as described in Figure 1.15.

Theories and lawsPeople use the word theory in

everyday life very differently from theway scientists use this word in theirwork. You may have heard someonesay that he or she has a theory that aparticular football team will win theSuper Bowl this year. What the per-son really means is that he or shebelieves one team will play better forsome reason. Much more evidence isneeded to support a scientific theory.

In science, a hypothesis that is sup-ported by many separate observationsand investigations, usually over a longperiod of time, becomes a theory. Atheory is an explanation of a naturalphenomenon that is supported by alarge body of scientific evidenceobtained from many different investi-gations and observations. A theoryresults from continual verificationand refinement of a hypothesis.

In addition to theories, scientistsalso recognize certain natural lawsthat are generally known to be true.The fact that a dropped apple falls to Earth is an illustration of the law of gravity.

Understanding Main Ideas1. Suppose you observed that bees prefer a yellow

flower that produces more nectar over a purpleflower that produces less nectar. List two separatehypotheses that you might make about bees andflowers.

2. Describe a controlled experiment you couldperform to determine whether ants are moreattracted to butter or to honey.

3. What is the difference between a theory and ahypothesis?

4. Why do some investigations require a control?

Thinking Critically5. Describe a way that a baker might conduct

a controlled experiment with a cookie recipe.

6. Interpret Scientific Illustrations Review Figure 1.14. What happens when a hypothesis is not supported? How does the strength of a scientific theory compare to the strength of a hypothesis? For more help, refer to Interpret Scientific Illustrations in the SkillHandbook.

SKILL REVIEWSKILL REVIEW

Figure 1.15Investigations haveshown that male ele-phants communicatewith other males usingthreat postures andlow-frequency vibra-tions that warn rivalmales away.

18 BIOLOGY: THE STUDY OF LIFE ca.bdol.glencoe.com/self_check_quiz

Check for UnderstandingProvide students with scientif-ic methods listed. Ask studentsto describe the steps.

ReteachAsk students to outline thesteps used in scientific meth-ods. For each level of the out-line, have them provide anexample taken from studiesdescribed in the text.

ResourcesFor more practice, useReading Essentials for Biology, Section 1.2.

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ExtensionHave students look up cell theoryin this textbook. Ask them whathypotheses may have been madeby each of the scientists who firstdiscovered cells.

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BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES

Use with Chapter 1,Section 1.3

The person in the picture is measuring in cubits—anancient Egyptian measurement that equals the distancefrom a person’s elbow to the tip of the middle finger.What problems might occur if everyone used this unit?

What characteristics should a measurement system haveto make it accurate and easily understood by everyone?

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Transparency Systems of Measurement3

1 FocusBellringerSection Focus Transparency 3

Using PriorKnowledgeOrganize Information Quan-titative methods for describingthe class include numbers, suchas heights of students, numberof minutes in the class, andnumber of students absent.Qualitative methods might usebehavioral differences betweenstudents, colors of clothing, ortype of footwear worn to class.

Aaron Haupt

1.3SECTION PREVIEWObjectivesCompare and contrastquantitative and qualitativeinformation.Explain why science andtechnology cannot solveall problems.

Review Vocabularyexperiment: procedure

that tests a hypothesis by collecting informa-tion (p. 13)

New Vocabularyethicstechnology

1.3 THE NATURE OF BIOLOGY 19

Two Ways to Describe ThingsUsing Prior Knowledge How would youdescribe your homeroom class? Wouldyou mention how many classmates youhave? Or would you describe them asgood students? Would you tellsomeone how many boys or howmany girls comprise the class?Perhaps you would narrate howyour classmates carried out anexperiment. Most information youcould give would be either quanti-tative or qualitative. Quantitativeinformation uses numbers or meas-urements, while qualitative informa-tion expresses qualities and behavior.Organize Information Make a list of waysyou could describe your class. Divide the list into two categories: Quantitative and Qualitative.

Kinds of InformationYou have learned that scientists use a variety of methods to test their

hypotheses about the natural world. Scientific information can usually beclassified into one of two main types, quantitative or qualitative.

Quantitative informationBiologists sometimes conduct controlled experiments that result in

counts or measurements—that is, numerical data. These kinds of experi-ments occur in quantitative research. The data are analyzed by compar-ing numerical values.

Quantitative data may be used to make a graph or table. Graphs andtables communicate large amounts of data in a form that is easy to under-stand. Suppose, for example, that a biologist is studying the effects of cli-mate on freshwater life. He or she may count the number of microscopicorganisms, called Paramecium, that survive at a given temperature. Thisstudy is an example of quantitative research.

The data obtained from the Paramecium study is presented as a graphin Figure 1.16. You can practice using graphs by carrying out theProblem-Solving Lab on the next page.

This group of students can bedescribed with quantitative orqualitative information.

The Nature of BiologyStandard 1g Students will recognize the usefulness and limitations of

models and theories as scientific representations of reality.California Standards

Unit 1 FAST FILE ResourcesMiniLab Worksheet, p. 7Reinforcement and Study Guide in

English, p.16Reinforcement and Study Guide in

Spanish, p. 20Transparency Worksheet, p. 23

Reading Essentials for Biology,Section 1.3

Section Focus Transparency 3 Pages 18–19: Inv. & Exp. 1f

20

Purpose Students will analyze a graph anddetermine that the amount ofinformation obtained from agraph is limited.

Process Skillsacquire information, interpretdata, think critically

Teaching StrategiesReview the terminology associat-ed with graphs or refer studentsto the Skill Handbook.

Thinking Critically1. no; No bar extends to the

100% line.2. The number of students

enrolled in physical educa-tion declines as studentsprogress from 9th grade to12th grade.

3. Data needed to answer thequestion are not supplied.

4. no; The graph does not pro-vide this information.

AssessmentSkill Have students design agraph to illustrate why fewer sen-iors take physical education.Students can make up the ques-tions to be surveyed and estimatethe number of “yes” responses.Use the Performance Task Ass-essment List for Conducting aSurvey and Graphing the Resultsin PASC, p. 107.

Caption Question AnswerFigure 1.16 Quantitative infor-mation is represented by thegraph.

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Measuring in the International System

It is important that scientificresearch be understandable to scien-tists around the world. For example,what if scientists in the UnitedStates reported quantitative data ininches, feet, yards, ounces, pounds,pints, quarts, and gallons? People inmany other countries would havetrouble understanding these databecause they are unfamiliar with theEnglish system of measurement.Instead, scientists always reportmeasurements in a form of the met-ric system called the InternationalSystem of Measurement, commonlyknown as SI.

One advantage of SI is that thereare only a few basic units, and nearlyall measurements can be expressed inthese units or combinations of them.The greatest advantage is that SI, likethe metric system, is a decimal sys-tem. Measurements can be expressedin multiples of tens or tenths of abasic unit by applying a standard setof prefixes to the unit. In biology, themetric units you will encounter mostoften are meter (length), gram (mass),

M. Abbey/Photo Researchers

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Paramecium Survival RatesFigure 1.16This graph shows how many paramecia—microscopic organisms—survive as the tem-perature increases. Infer What type ofinformation is represented by thegraph?

ParameciumLM Magnification: 65�

20 BIOLOGY: THE STUDY OF LIFE

Make and Use GraphsWhat can be learnedfrom a graph? One wayto express information is topresent it in the form of agraph. The amount of infor-mation available from agraph depends on thenature of the graph itself.

Solve the ProblemStudy the graph at right.Answer the questions that follow and note the type ofinformation that can and cannot be answered fromthe graph itself.

Thinking Critically1. Observe Is there ever a

year in high school when all students are enrolled in physical education? Explain your answer.

2. Infer Is there a relationship between the number of students enrolled in physical education and their year ofhigh school? Explain your answer.

3. Observe Can you tell which states in the country have thelargest number of students enrolled in physical education?

4. Infer Based on the graph, can you explain why so few students take physical education in their senior year?

U.S. Students Enrolled in Physical Education

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Units and Standards The SI system isused in 95% of the countries in theworld. It provides a standardized systemof measurement for scientific communi-cation. The ancient Egyptians used a unitcalled the cubit, which was based on thelength of the arm from elbow to tip of

the longest finger. Because sizes of indi-viduals varied, the size of the unit varied.In England, a foot was the length of thefoot of the king. When a new king cameto power, the length became the size ofhis foot. Have students research measur-ing systems used around the world. L3

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(l)Art Wolfe (r)Luiz C. Marigo/Peter Arnold, Inc.

liter (volume), second (time), andCelsius degree (temperature). For athorough review of measurement inSI, see Math and Problem-SolvingSkills in the Skill Handbook.

Explain why scientists use the SI system.

Qualitative information Do you think the behavior of the

animals shown in Figure 1.17 wouldbe easier to explain with numbers or with written descriptions of whatthe animals did? Observational data—that is, written descriptions ofwhat scientists observe—are oftenjust as important in the solution of a scientific problem as numerical data.

When biologists use purely obser-vational data, they are using qualitativeinformation. Qualitative informationis useful because some phenomenaaren’t easily expressed as quantita-tive information. For example, thealbatross example on page 13 cannoteasily be illustrated with numbers.Practice your investigative skills inthe MiniLab on the next page.

Science and SocietyThe road to scientific discovery

includes making observations, for-mulating hypotheses, performing

investigations, collecting and analyz-ing data, drawing conclusions, andreporting results in scientific jour-nals. No matter what methods scien-tists choose, their research oftenprovides society with importantinformation that can be put to prac-tical use.

Maybe you have heard peopleblame scientists for the existence ofnuclear bombs or controversialdrugs. To comprehend the nature ofscience in general, and biology inparticular, people must understandthat knowledge gained through scientific research is never inherentlygood or bad. Notions of good andbad arise out of human social, ethi-cal, and moral concerns. Ethicsrefers to the moral principles andvalues held by humans. Scientistsmight not consider all the possibleapplications for the products of theirresearch when planning their inves-tigations. Society as a whole musttake responsibility for the ethical useof scientific discoveries.

Can science answer all questions?

Some questions are simply not inthe realm of science. Such questionsmay involve decisions regarding goodversus evil, ugly versus beautiful, orsimilar judgments. There are also sci-entific questions that cannot be

1.3 THE NATURE OF BIOLOGY 21

Figure 1.17What kinds of information aregained by observing these animals?

Penguins cannot fly. They use theirwings for swimming in the oceansof the southern hemisphere.

A

technology fromthe Greek wordstechne, meaningan “art or skill,”and logos, mean-ing “study”; Tech-nology is theapplication of sci-ence in our dailylives.

Toucans live in therain forests ofSouth America.

B

Types of ObservationsProvide students with ametric ruler and a clump ofpine needles. Ask them tomake two lists of observa-tions: one that describes theneedles with words andanother that uses measure-ments. Have students com-pare their lists with classmates. L1

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EnrichmentHave students list quantitativeand qualitative information aboutfive common animals. Have thempresent their data to the class andhave the class use the data toidentify the animals beingdescribed. Ask which type of datawas most useful in attempting toidentify the animals and have stu-dents explain why. Quantitativedata, such as size and number ofappendages, may be too similarfor many of the animals, where-as qualitative data, such as pres-ence of fur or feathers, commoncolors, and descriptions ofbehavioral traits, may be morespecific.

Caption Question AnswerFigure 1.17 Types of food eaten,preferred habitat, and behaviorare kinds of information thatcan be found by doing qualita-tive research.

Scientists usethe SI system because it isunderstood by scientistseverywhere and uses only afew basic units.

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Making Predictions Have students pre-dict the chance that a coin, when flipped,will come up heads. 50% How manyheads should appear if a coin is flipped10 times? 1/2 � 10 or 5 How many headsshould appear if a coin is flipped 100times? 1/2 � 100 or 50 Ask them to carry

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Purpose Students make observations andinferences and design an experi-ment that tests a hypothesis.

Process Skillsobserve and infer, hypothesize,collect data, design an experiment

Safety PrecautionsPour the boiling water for thestudents. Do not have studentspour it.

Teaching Strategies■ Provide each group of students

with two “dinosaur eggs” fromspecially marked packages ofoatmeal. Each serving packetcontains about 14 eggs.

■ Ask students to explain whythis experiment would not bepossible with real eggs.

Expected ResultsThe outer candy layer of a“dinosaur egg” dissolves in boil-ing water in less than a minute,leaving a dinosaur-shaped candy.

Analysis1. Answers will vary.2. To test heat, students might

put eggs under a heat lamp.To test moisture, studentsmight place eggs in varioustemperatures of water. Var-iable is heat or moisture.Control is the basis of compar-ison for the tested condition.Students could measure“hatching” time. Use as manyeggs and trials as time permits.

AssessmentPerformance Have studentsconduct the experiment theydesign. Use the Performance TaskAssessment List for Carrying Outa Strategy and Collecting Data inPASC, p. 97. L2

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tested using scientific methods.However, this does not mean thatthese questions are unimportant.

Consider a particular questionthat is not testable. Some peopleassert that if a black cat crosses yourpath, you will have bad luck. On thesurface, that hypothesis appears tobe one that you could test. But whatis bad luck, and how long would youhave to wait for the bad luck tooccur? How would you distinguishbetween bad luck caused by theblack cat and bad luck that occurs atrandom? Once you examine thequestion, you can see there is no wayto test it scientifically because youcannot devise a controlled experi-ment that would yield valid data.

Can technology solve all problems?

Science attempts to explain howand why things happen. Scientificstudy that is carried out mainly forthe sake of knowledge—with noimmediate interest in applying theresults to daily living—is called purescience.

However, much of pure scienceeventually does have an impact onpeople’s lives. Have you everthought about what it was like to livein the world before the developmentof water treatment plants, vaccina-tions, antibiotics, or high-yieldingcrops? These and other life-savingdevelopments, such as the brain scanshown in Figure 1.18, are indirectresults of research done by scientistsin many different fields over hun-dreds of years.

Other scientists work in researchthat has obvious and immediateapplications. Technology (tek NAH

luh jee) is the application of scien-tific research to society’s needs andproblems. It is concerned with mak-ing improvements in human life and

22 BIOLOGY: THE STUDY OF LIFEWill & Deni McIntyre/Photo Researchers

Figure 1.18Technology allowsdoctors to developand use bettertools to diagnosemedical problems.

Observe and InferHatching Dinosaurs Candy “dinosaur eggs” can be found in specially marked packages of oatmeal. You will conduct aninvestigation to determine what causes these pretend eggs to hatch.

Procedure

! Copy the data table above.@ Observe the dinosaur eggs provided, and record their

characteristics in your table.# Place an egg in each of two containers.$ Form a hypothesis about the water temperature that will

cause the eggs to hatch.% Pour hot water into one container and cold water in the

other. CAUTION: Be careful with hot water. Stir for oneminute. Record your observations.

Analysis1. Analyze Data Was your hypothesis supported? How

would you revise it using the new information?2. Experiment Design an experiment that would test either

heat or moisture as the variable. What kind of quantita-tive data will you gather? What will be your control? Howmany trials will you run and how many eggs will you test?If time permits, conduct your experiment.

Data Table

Before Hot Water Cold WaterTreatment Treatment Treatment

Appearance after one minute

Learning Disabled Create three dis-plays of objects on a table in front ofthe classroom. Have the studentswrite one qualitative term and onequantitative term to describe eachdisplay. L1

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1. to see if the results are repeatable,thus confirming their authenticity;original hypothesis may need to berevised

2. Quantitative information reports datain numerical values based on measur-ing. Qualitative information reportsdata in descriptions based on observa-tions.

3. The processes of science are used toanswer questions about or raised by sci-entific facts or information.

4. Some problems do not have a scientificbasis. Some technological solutions maypose more problems than they solve.

5. The biomedical researchers sought to increase knowledge. The application

of the resulting technology is a ques-tion society must answer.

6. Paramecia die above a certain temper-ature. This results in a rapid drop innumbers once this temperature isreached. They are better able to sur-vive as low temperatures rise, thus thegraph reflects this increased survival.

Richard Hamilton Smith/CORBIS

the world around us. Technologyhas helped increase the productionof food, reduced the amount ofmanual labor needed to make prod-ucts and raise crops, and aided in thereduction of wastes and environ-mental pollution.

The advance of technology hasbenefited humans in numerous ways,but it has also resulted in some seri-ous problems. For example, fertilizeris often used to boost the productionof food crops, such as the cornshown in Figure 1.19. If more fertil-izer is applied than the plants areable to use, the excess fertilizer canflow into streams or even oceans.Excess nitrogen has been shown tocause problems with some coral reefsby promoting the growth of algae.

Science and technology will neveranswer all of the questions we ask,nor will they solve all of our prob-lems. However, during your study ofbiology you will have many of yourquestions answered, and you willexplore many new concepts. As youlearn more about living things,remember that you are a part of theliving world, and you can use theprocesses of science to ask andanswer questions about that world.

Understanding Main Ideas1. Why is it important that scientific investigations

be repeated? What happens when other scientistsachieve different results when repeating an investigation?

2. Compare and contrast quantitative and qualita-tive. Explain how both types of information areimportant to biological studies.

3. Why is science considered to be a combination ofinformation and process?

4. Why is technology not the solution to all scientificproblems?

Thinking Critically5. Biomedical research has led to the development of

technology that can keep ill or incapacitatedpatients alive. How does this technology addressthe question of when such measures should beused on patients?

6. Make and Use Graphs Look at the graph inFigure 1.16. Why do you think that the high-temperature side of the graph drops off more sharplythan the low-temperature side? For more help, referto Make and Use Graphs in the Skill Handbook.

SKILL REVIEWSKILL REVIEW

1.3 THE NATURE OF BIOLOGY 23

Figure 1.19Technology allows farmers to use fertilizers that increase their crop pro-duction in order to meet the world’s food needs. Crop yields from thisfield of corn are maximized with the use of improved plant breeds andfertilizer in order to feed the world’s growing population.

ca.bdol.glencoe.com/self_check_quiz

Check for UnderstandingHave students provide anexample of: quantitativeinformation, qualitativeinformation, a contributionof technology, and an ethicalissue in science.

ReteachAsk students to prepare anoutline of the major conceptsof this section.

ResourcesFor more practice, useReading Essentials forBiology, Section 1.3.

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ExtensionLogical-Mathematical Have stu-dents research the idea of “beingable to beat cancer with a strongpositive mental attitude.” Havethem explain why it may be diffi-cult to evaluate scientifically how apositive mental attitude contributesto recovery from disease.

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Before YouBegin

Seeing different life forms,and even interacting withthem, is pretty much partof a typical day. Petting adog, swatting at a fly, cut-ting the grass, and talkingto your friends are com-mon examples. But, haveyou ever asked yourselfthe question, “What do allof these different lifeforms have in common?”

24 BIOLOGY: THE STUDY OF LIFE

Collecting Biological Data

ProblemWhat life characteristics can be observed in a pill bug?

ObjectivesIn this BioLab, you will:■ Observe whether life characteristics are

present in a pill bug.■ Measure the length of a pill bug.■ Experiment to determine if a pill bug

responds to changes in its environment.■ Use the Internet to collect and compare

data from other students.

Materialspill bugs, Armadillidium rulerwatch or classroom clock internet connectioncontainer, glass or plastic pencil with dull point

Safety PrecautionsCAUTION: Always wear goggles in the lab.

Skill HandbookIf you need help with this lab, refer to the Skill Handbook.

1. Make copies of the data table andgraph outlines.

2. Obtain a pill bug from your teacherand place it in a small container.

3. Observe your pill bug to determine if it has an orderly structure. Recordyour observations in the data table.

4. Using millimeters, measure andrecord the length of your pill bug inthe data table.

5. Using your data and data from yourclassmates, complete the graph “PillBug Length: Classroom Data.”

PROCEDUREPROCEDURE

PREPARATIONPREPARATION

Time in SecondsTrial

Response to Environment

Orderly structure?

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Organization and Growth and Development

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Teaching Strategies■ Allow students to work in small groups of

two or three. ■ Make sure that students have already cov-

ered the section dealing with life charac-teristics before attempting this activity.

■ Review the procedure for determining anaverage. Have students round off theiraverage data on the length of time in sec-onds the pill bug remains rolled up.

Time Allotmentone class period

Process Skillscollect data, define operationally,experiment, observe and infer,acquire information, think criti-cally, communicate

Safety PrecautionsRemind students to treat live ani-mals gently and follow directionscarefully. Have students weargoggles, lab aprons, and dispos-able gloves. Following the lab,students should wash hands thor-oughly with soap and water.

Pill bugs—also called sow bugs,wood lice, or isopods—may becollected locally or purchasedfrom a biological supply house.Armadillidium vulgare is the onlyspecies that will roll tightly into a“pill,” so it is preferred for thisactivity.

Troubleshooting■ Students may have difficulty

assessing whether pill bugsshow an orderly structure.Advise them to make a “bestguess” to answer this question.

■ Review the technique forpreparing a histogram beforeyou begin.

PROCEDUREPROCEDURE

PREPARATIONPREPARATION

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ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

1.3 THE NATURE OF BIOLOGY 25

6. Go to to post your data.

7. Gently touch the underside of the pill bug with a dull pencil point. CAUTION: Use care to avoidinjuring the pill bug.

8. Note its response and time, in seconds, how long the animalremains curled up. Record the time in the data table as Trial 1.

9. Repeat steps 7–8 four more times, recording each trial in the data table.

10. Calculate the average length of time your pill bug remains curled up.

11. Post your data at.

12. Wash your hands after working with pill bugs. Return the pill bug to your teacher and suggest ways to release or reuse the bugs wisely.

CLEANUP AND DISPOSAL

Length in millimeters1

10987654321

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ca.bdol.glencoe.com/

ca.bdol.glencoe.com/internet_lab

internet_lab

ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

1. Think Critically Define the term “orderlystructure.” Explain how this trait also pertainsto nonliving things.

2. Use the Internet Explain how data from theclassroom and Internet graphs support theidea that pill bugs grow and develop.

3. Interpret Data What was the most commonlength of time pill bugs remained curled inresponse to being touched?

4. Draw a Conclusion Explain how theresponse to being touched is an adaptation.

5. Experiment How might you design anexperiment to determine whether or not pillbugs reproduce?

6. How might you collect oranalyze data to better define a living organism?ERROR ANALYSIS

ca.bdol.glencoe.com/internet_lab

Find this BioLab using the link below, andpost your data in the data table provided forthis activity. Using the additional data fromother students on the Internet, analyze thecombined data, and complete your graphs.

1. Student answers will varyand may include the follow-ing: shows organization; hasspecific parts for certain jobs;all pill bugs look alike. Yes,orderly structure also appliesto nonliving things. Manynonliving things are organ-ized, including buildings,books, computers.

2. The graph shows that pillbugs vary in length, but mostreach a maximum size ofabout 10 mm.

3. Pill bugs remain curled for anaverage of approximately 20seconds.

4. The pill bugs’ outer shell israther tough; rolling into aball could prevent predatorsfrom attacking its soft under-side and fragile appendages.

5. Student answers will vary.Place several pill bugs in asealed container and addfood and moisture as need-ed. Observe pill bugs weeklyand compare numbers pres-ent to those originally placedin container. Or, look forimmature forms that mayappear in the container.

6. Studentsmay suggest other types of information that wouldshow that pill bugs are livingthings.

ERROR ANALYSIS

ANALYZE AND CONCLUDEANALYZE AND CONCLUDE

25

To navigate the InternetBioLab, go to

. Studentsshould post their data in thedata table provided. Toexpand this activity, haveyour students randomlychoose data supplied byother students to determinehow the average times differ.

ca.bdol.glencoe.com/internet_lab

Data and ObservationsStudents should conclude that pill bugs showorganization, undergo growth and develop-ment, and adjust to their environment. Pillbugs will remain rolled in a ball for approxi-mately 20 seconds. Typical length of amature pill bug is 10 mm.

AssessmentSkill Ask students to prepare a graph of datathat would be representative of the experi-mental results from “Share Your Data.”Refer students to Make and Use Graphs in theSkill Handbook. Use the Performance TaskAssessment List for Graph from Data inPASC, p. 111. L2

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26

PurposeThis feature allows students toanalyze claims made about organ-ically grown produce. Studentsare encouraged to formulate andpresent their own views.

Teaching Strategies■ Provide recent newspaper and

magazine articles regardingclaims about organically grownproduce.

■ Ask students to discuss theadvantages and disadvantagesof using herbicides, pesticides,and fertilizers on crops.

■ Have students interview pro-duce managers in severalsupermarkets to obtain theirviews concerning organicallygrown produce.

■ Have students investigate themethods used for displayingproduce in supermarkets. Askthem to write a summary oftheir findings.

Standards will differ. Look forrecent research findings on typesand amounts of pesticides, aswell as analysis of productslabelled as organic. Studentsshould take positions based ontheir research and use this infor-mation in a debate. As part ofthe debate, students should pres-ent various forms of promotionalclaims about organic foods andevaluate those claims.

L2

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L3

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Bring samples of organicand conventional produceto class. Ask students tocompare the cost, appear-ance, and (with parent orguardian permission) tasteof the samples and discusshow price, appearance, andtaste might affect consumerpurchase decisions. L1

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26 BIOLOGY: THE STUDY OF LIFE

The produce section of the supermarket has twobins of leafy lettuce that look very much alike.

One is labeled “organic” and has a higher price.More and more consumers are willing to payextra for organically grown fruits, vegetables,meats, and dairy products. What are they payingthat extra money for?

The term “organic” usually refers to foodsthat are produced without the use of chemicalpesticides, herbicides, or fertilizers. Organicfarmers use nonchemical methods to controlpests and encourage crop growth. Beneficialinsects, such as ladybugs and Trichogrammawasps, are brought in to feed on aphids, cater-pillars, and other damaging insects. Instead ofapplying herbicides, organic farmers pull weedsby hand or by machine. In place of fertilizers,they use composting and crop rotation toenrich the soil. Organic farming is very laborintensive, so organic foods are usually moreexpensive than those produced by conventionalmethods.

Perspectives People usually buy organic prod-ucts because they want to be sure they’re gettingnutritious food with no chemical residues. Butthere are differences of opinion about how muchbetter organic food actually is, and even whichfoods should be called organic.

Is organic food healthier? Agricultural chemicals can leave residues on food and contami-nate drinking water supplies. Since exposure tosome chemicals is known to cause health prob-lems, including cancer, many consumers thinkthat organic foods are healthier. Chemical pestcontrols kill beneficial organisms as well asunwanted pests, and can adversely affect thehealth of other animals, especially those thatfeed on insects. Organic pest control methodsusually target specific pests and have little effecton beneficial organisms.

Organic Food: Is it healthier?

(t)Jeff Greenberg/Visuals Unlimited (b)KS Studios

Produce from an organic farm

Conventionally grownfood: Low cost, higher yield? Chemicalfertilizers and pesticides make it possible togrow larger crops at lower cost, which makesmore food available to more people. Makingsure everyone can afford an adequate supply offruits and vegetables may be more importantthan the risk of disease posed by agriculturalchemicals.

Not everyone agrees about what is organic andwhat isn’t. Should genetically engineered plantor animal foods be considered organic? Whatabout herbs or meats preserved by irradiation,or lettuce and tomatoes fertilized with sewagesludge?

ca.bdol.glencoe.com/biology_society

Analyze the Issue Use resources to investigate your state’s standards for labeling food products as “organic.” Look for research that shows that organically grown food is safer than conventionallygrown food. Describe your findings in your sciencejournal.

To find out more about organic food, visit

Use the ExamView®Pro Test Bank CD-ROM to:• Create multiple versions of tests• Create modified tests with one mouse click for inclusion students• Edit existing questions and add your own questions• Build tests aligned with state standards using built-in

State Curriculum Tags• Change English tests to Spanish with one mouse click and vice versa

Key ConceptsSummary statements can beused by students to review themajor concepts of the chapter.

Visit /self_check_quiz/vocabulary_puzzlemaker/chapter_test/standardized_test

27

Section 1.1

(t)Steve E. Ross/Photo Researchers (c)Gerry Ellis/ENP Images (b)Luiz C. Marigo/Peter Arnold, Inc.

Section 1.2

Section 1.3

Key Concepts■ Biology is the organized study of living

things and their interactions with theirnatural and physical environments.

■ All living things have four characteristics incommon: organization, reproduction,growth and development, and the ability toadjust to the environment.

Vocabularyadaptation (p. 9)biology (p. 3)development (p. 8)energy (p. 9)environment (p. 8)evolution (p. 10)growth (p. 8)homeostasis (p. 9)organism (p. 6)organization (p. 7)reproduction (p. 7)response (p. 9)species (p. 7)stimulus (p. 9)

What isbiology?

Key Concepts■ Biologists use controlled experiments to

obtain data that either do or do not sup-port a hypothesis. By publishing the resultsand conclusions of an experiment, a scien-tist allows others to try to verify theresults. Repeated verification over timeleads to the development of a theory.

■ Scientific methods are used by scientists toanswer questions or solve problems.Scientific methods include observing, mak-ing a hypothesis, collecting data, publish-ing results, forming a theory, developingnew hypotheses, and revising the theory.

Vocabularycontrol (p. 13)data (p. 15)dependent variable

(p. 13)experiment (p. 13)hypothesis (p. 12)independent variable

(p. 13)safety symbol (p. 15)scientific methods (p. 11)theory (p. 18)

Key Concepts■ Biologists do their work in laboratories

and in the field. They collect both quanti-tative and qualitative data from theirexperiments and investigations.

■ Scientists conduct investigations toincrease knowledge about the naturalworld. Scientific results may help solvesome problems, but not all.

Vocabularyethics (p. 21)technology (p. 22)

The Methods ofBiology

The Nature ofBiology

CHAPTER 1 ASSESSMENT 27

STUDY GUIDESTUDY GUIDE

To help you review thecharacteristics of living things, use theOrganizational Study Fold on page 3.

ca.bdol.glencoe.com/vocabulary_puzzlemaker

ca.bdol.glencoe.com

For additional helpwith vocabulary,have students

access the VocabularyPuzzleMaker online atca.bdol.glencoe.com/vocabulary_puzzlemaker

FOLDABLES™Have students use theirFoldables to review content inSection 1.1. On the back of thepaper, write a hypothesis abouthow each of the three organ-isms would survive in a habitatdifferent from the one it usuallylives in. In what way would theyeach have to adapt?

Pages 26–27: Inv. & Exp. 1f, 1j, 1m

Questions andanswers have been

aligned and verified by ThePrinceton Review.

1. technology2. adaptation3. organism4. species5. hypothesis

6. B 8. B7. D 9. D

10. It is composed of cells, whichare organized into tissuesand organs, which areorganized into body systems.

11. Biometrics is used as ananalysis tool, but recentlybiometrics has been used asan instrument for identifi-cation as well.

12. Evolution is the result ofspecies adapting to environ-mental change.

13. open flame alert14. Students may agree or dis-

agree with Congressionalviews, but their opinionsshould be supported. Ex-ample: a student may be ofthe opinion that humancloning should not beallowed based on a beliefthat additional technologymay only pose additional ormore troublesome problems.

Evaluating Open-Ended QuestionsOpen-ended assessment questions aregraded by using a multilevel rubricthat guides you in assessing a stu-dent’s knowledge of a particular con-cept. The following rubric is a samplescoring device.

28

Carolyn A. McKeone/Photo Researchers

28 CHAPTER 1 ASSESSMENT

Review the Chapter 1 vocabulary words listed inthe Study Guide on page 27. Match the wordswith the definitions below.

1. the application of scientific research to soci-ety’s needs and problems

2. any structure, behavior, or internal processthat enables an organism to respond to environmental factors and live to produceoffspring

3. anything that possesses all the characteristicsof life

4. a group of organisms that can interbreedand produce fertile offspring in nature

5. an explanation for a question or problemthat can be tested

6. Which of the following is not an appropriatequestion for science to consider?A. How many seals can a killer whale con-

sume in a day?B. Which type of orchid flower is most

beautiful?C. What birds prefer seeds as a food source?D. When do hoofed mammals in Africa

migrate northward?7. Similar-looking organisms, such as the dogs

shown below, that can interbreed and pro-duce fertile offspring are called ________.A. a living system C. organizationB. an adaptation D. a species

8. If data from repeated experiments do notsupport the hypothesis, what is the scientist’snext step?A. Declare the experiment unsuccessful.B. Revise the hypothesis.C. Repeat the experiment.D. Overturn the theory.

9. The single factor that is altered in anexperiment is the ________.A. controlB. dependent variableC. hypothesisD. independent variable

10. Open Ended Describe how the human bodyshows the life characteristic of organization.

11. Open Ended Scientists use quantitative datato derive mathematical models, termed bio-metrics. Research two definitions and uses ofbiometrics in today’s society.

12. Describe Explain the relationships among an organism’s environment, adaptations, andevolution.

13. Interpret An experiment involves heatingchemicals in a test tube over a flame. Whichof the safety symbols shown above should beused in the experiment? Which symbol fromthe Skill Handbook is needed above, butmissing from this table?

14. Recently mem-bers of Congress have debated the issue ofhuman cloning. Visit to investigate this debate. Write an essayexpressing your opinion. Use reasoningbased on your understanding of the debateto support your opinion. Present your opin-ion in a debate with members of your class.

REAL WORLD BIOCHALLENGE

Table 1.1 Safety Symbols

Sharp Object Safety This symbol appears when a danger ofcuts or punctures caused by the use of sharp objects exists.

Clothing Protection Safety This symbol appears whensubstances used could stain or burn clothing.

Eye Safety This symbol appears when a danger to the eyes exists. Safety goggles should be worn when this symbol appears.

Chemical Safety This symbol appears when chemicals used can cause burns or are poisonous if absorbed through the skin.

ca.bdol.glencoe.com

ca.bdol.glencoe.com/chapter_test

Pages 28–29: Inv. & Exp. 1g

CHAPTER ASSESSMENT CHAPTER 1 Biology: The Study of Life 33

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AssessmentStudent Recording Sheet

Name Date Class

Chapter

1Chapter Chapter AssessmentChapter Assessment

Use with pages 28–29 ofthe Student Edition

Standardized Test Practice

Vocabulary ReviewWrite the vocabulary words that match the definitions in your book.

1. _________________________ 4. _______________________

2. _________________________ 5. _______________________

3. _________________________

Understanding Key ConceptsSelect the best answer from the choices given and fill in the corresponding oval.

6.

7.

8.

9.

Constructed ResponseRecord your answers for Questions 10–12 on a separate sheet of paper.

Thinking CriticallyRecord your answer for Question 13 on a separate sheet of paper.14. Follow your teacher’s instructions for presenting your BioChallenge answer.REAL WORLD BIOCHALLENGE

Part 1 Multiple ChoiceSelect the best answer from the choices givenand fill in the corresponding oval.

15.

16.

17.

18.

19.

20.

21.

Part 2Constructed Response/Grid InRecord your answers for Questions 22 and 23 on a separate sheet of paper.

A B C D

A B C D

A B C D

A B C D

A B C D

A B C D

A B C D

A B C D

A B C D

A B C D

A B C D

29

15. B 18. B16. D 19. A17. C 20. B21. Ethics, the principles and

values held by humans,often determine whethercertain experiments areperformed. The benefits ofa procedure are weighedagainst possible harm tothe individual and to socie-ty. This is one way that sci-ence is limited.

22. A flame uses energy, canmove, and grow large.Bubbles and balloons move.However, none of these hasall of the characteristics ofliving things.

Answer Sheet A practiceanswer sheet can be found on p. 33 of Unit 1 FAST FILE

Resources.

CHAPTER 1 ASSESSMENT 29

Constructed Response/Grid In

Record your answers on your answer document.

21. Open Ended Why does a panel of doctors, lawyers, clergy, and others sometimes convene todetermine if an experimental operation should be allowed on human patients?

22. Open Ended Consider the following items: a flame, bubbles blown from a bubble wand, and aballoon released into the air. Describe characteristics of each that might indicate life and thosethat indicate they are not alive.

ca.bdol.glencoe.com/standardized_test

Multiple Choice

A team of students measured the number of seedsthat germinated over ten days in a control group at18°C and in an experimental group at 25°C. Theygraphed their data as shown above. Study thegraph and answer questions 15–18.

15. Which of the following best represents thehypothesis tested?A. Black seeds are best.B. Seeds germinate faster at warmer

temperatures.C. Fertilization of seeds requires heat.D. Seeds germinate when freezing.

16. When did the experiment end?A. day 3 C. day 7B. day 6 D. day 10

17. Which of the following was the independentvariable?A. kind of seedsB. number germinatingC. temperatureD. time

18. Which of the following was the dependentvariable?A. kind of seedsB. number germinatingC. temperatureD. time

Use the drawing below to answer question 19.

19. In scientific investigations it is important tocollect data and make measurements with precision. A graduatedcylinder is often used to measure volumes ofliquids accurately andprecisely. The surface of many liquids in a graduated cylinder forms a curved surfacecalled a meniscus. Whatis the volume of fluid inthe graduated cylinder shown on the right?A. 79 mL C. 81 mLB. 80 mL D. 75 mL

20. Which of the following statements is true ofa theory?A. A theory is considered true and never

changes.B. A theory makes predictions about

unknown phenomena.C. A theory is the same thing as a hypothesis.D. A theory is the usual outcome of an

experiment.

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The assessed California standard appears next to the question.

California StandardsPractice

SCORE CRITERIA4 A correct solution that is sup-

ported by well-developed,accurate explanations.

3 A generally correct solution,but may contain minor flaws inreasoning.

SCORE CRITERIA2 A partially correct interpretation

and/or solution to the problem.1 A correct solution with no sup-

porting evidence or explanation. 0 An incorrect solution or no

solution is given.

3030

What is biology?Living things abound almost everywhere

on Earth—in deep ocean trenches, atop the highest mountains, in dry deserts, and in wet tropical forests. Biology is the study of living organisms and the interactions among them. Biologists use a variety of scientific methods to study the details of life.

30 BIODIGEST UNIT 1 REVIEW

Characteristics of LifeBiologists have formulated a list of characteris-

tics by which we can recognize living things.

OrganizationAll living things are organized into cells.

Organisms may be composed of one cell or manycells. Cells are like rooms in a building. You canthink of a many-celled organism as a building con-taining many rooms. Groups of rooms in differentareas of the building are used for different pur-poses. These areas are analogous to the tissues,organs, and body systems of plants and animals.

HomeostasisA stable internal environment is necessary for

life. Organisms maintain this stability throughhomeostasis, which is a process that requires thecontrolled use of energy in cells. Plants obtainenergy by converting light, water, and carbondioxide into food. Other organisms obtain theirenergy indirectly from plants.

Response to a StimulusLiving things respond to changes in their exter-

nal environment. Any change, such as a rise intemperature or the presence of food, is a stimulus.

Growth and DevelopmentWhen living things grow, their cells enlarge and

divide. As organisms age, other changes also takeplace. Development consists of the changes in anorganism that take place over time.

ReproductionLiving things reproduce by transmitting their

hereditary information from one generation tothe next.

Scientific MethodsScientists employ a variety of scientific methods

to investigate questions and solve problems. Notall investigations will use all methods, and theorder in which they are used will vary.

ObservationCuriosity leads scientists to make observations

that raise questions about natural phenomena.

HypothesisA statement that can be tested and presents a

possible solution to a question is a hypothesis.

ExperimentAfter making a hypothesis, the next step is to

test it. An experiment is a formal method of test-ing a hypothesis. In a controlled experiment, twogroups are tested and all conditions except oneare kept the same for both groups. The single con-dition that changes is the independent variable.The condition caused by the change in the inde-pendent variable is called the dependent variable.

TheoryWhen a hypothesis has been confirmed by

many experiments, it may become a theory.Theories explain natural phenomena.

Arthur C. Twomey/Photo Researchers

Skill Provide students with anexample of a biological questionor problem. Have the class dis-cuss how they would use scien-tific methods to provide ananswer.

AssessmentAssessment

Unit 1 FAST FILE ResourcesReinforcement and Study Guide in

English, pp. 35–36Reinforcement and Study Guide in

Spanish, pp. 37–38Student Recording Sheet, p. 39

Pages 30–31: Inv. & Exp. 1f

PrepareShort on Time?This BioDigest can be used as abrief overview of the nature ofscience and the characteristics oflife. If time is limited, you maywish to use this unit summary toteach these concepts in place ofChapter 1.

Key ConceptsStudents are introduced to thecharacteristics of life and themethods of science. They learnabout the nature and limitationsof science and technology.

Bellringer Show students a candle flame anda caged mouse. Ask students toexplain the similarities and differ-ences of the two to elicit the char-acteristics of life.

Microscope ActivityVisual-Spatial Have studentsexamine slides of protists. Askwhat characteristics of life theorganisms share. L1

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L1

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Check for UnderstandingHave students explain why sci-ence and technology cannotanswer all questions.

ReteachVisual-Spatial Ask students toobserve a seed and make ahypothesis about whether it isalive. Have them plant the seedand record the characteristicsof life they note over the period of a week or two.

L2

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This page contains practice ques-tions in the various formats thatcan be found on the most fre-quently given standardized tests.

1. C 5. A

2. B 6. B

3. C 7. C

4. B 8. B

9. Cells would show cellularstructure; homeostasis isshown by making and usingenergy from sunlight; grow-ing toward the light is aresponse to stimulus; growthand development would beshown in the changes sincethe plant was a seed; repro-duction occurs when it pro-duces new seeds.

10. Fires can grow, use energy,and reproduce. Fires arenot composed of cells.

11. A control is a basis for comparison. A behaviorexperiment may not have a control.

12. Answers will vary.

Answer Sheet A practiceanswer sheet can be found on p. 39 of Unit 1 FAST FILE

Resources.

UNIT 1 STANDARDIZED TEST PRACTICE 31

Multiple Choice

1. The basic unit of organization of living thingsis a(n) ________.A. atom C. cellB. organism D. organ

2. Storing and periodically releasing energyobtained from food is an example of ________.A. evolution C. responseB. homeostasis D. growth

3. A hypothesis that is supported many times maybecome a(n) ________.A. experiment C. theoryB. conclusion D. observation

4. All of the procedures scientists use to answerquestions are ________.A. life characteristics C. researchB. scientific methods D. hypotheses

5. The environment includes ________.A. air, water, and weatherB. response to a stimulusC. adaptationsD. evolution

6. Which of the following is NOT a testablehypothesis?A. Fertilizer A will make the KW variety of

green bean produce more beans.B. Smart people like the same music.C. Vitamin C relieves cold symptoms.D. There is more than one species of African

elephant.

Use the lab procedure below to answer questions 7 and 8.

7. Which plot is the control group?A. the first plot with traditional pesticideB. the second plot with the new pesticideC. the third plot with no pesticideD. there is no control group

8. What could be concluded if the plot treated with the new pesticide has damage similar to the control plot?A. The experiment is a failure.B. The new pesticide may not be effective.C. The control plot was problematic.D. The new pesticide should be used.

Constructed Response/Grid In

Record your answers on your answer document.

9. Open Ended List the characteristics youwould check to see if a pine tree is a livingthing. Give an example that shows how thetree exhibits each characteristic.

10. Open Ended Compare the characteristics oflife with the flames of a fire. How are they sim-ilar and different?

11. Open Ended Why do most experiments have acontrol? Describe an experiment that does nothave a control.

12. Open Ended Evaluate the impact that scientificresearch has on society.

A group of scientists wishes to see if usinga new, environmentally friendly pesticideis effective in preventing insect damageto soybeans. Three different soybeanplots are planted. The first plot containssoybeans treated with the traditional pes-ticide. The second plot is treated with thenew environmentally friendly pesticide.The third plot is left untreated.

Maximize Your ScoreAsk how your test will be scored. In order to doyour best, you need to know if there is a penaltyfor guessing, and if so, how much of a penalty. Ifthere is no random-guessing penalty at all, youshould always fill in an answer.

ca.bdol.glencoe.com/standardized_test

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Standards Practice The assessed California standard appears next to the question.

31

For more help evaluatingopen-ended assessmentquestions, see the rubric on p. 9T.