1. chapter 1 student edition full

8/10/2019 1. Chapter 1 Student Edition Full

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UNIT

Chapters 1 The Science of Biolo

2 The Chemistry of Lif

INTRODUCEthe

The Nature of Life

Science is a way

of knowing a way of explain-ing the natural world through obser-

vations, questions, and experiments. Butscience isnt just dry old data, pressed

between pages of this book likeprom flowers in a school yearbook.Science is a living adventure story,aimed at understanding humansand the world around us. Thatstory begins with the relationshipbetween the matter that forms ourbodies and the energy

that powers lifesprocesses.

Science as a

Way of KnowingMatter and Energy


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Untamed Science Video Chapter Mystery

HEIGHTBY PRESCRIPTIONA doctor injects a chemical into

the body of an eight-year-oldboy named David. This

healthy boy shows no signs

of disease. The condition for which

he is being treated is quite common

David is short for his age. The

medication he is taking is human

growth hormone, or HGH.

HGH, together with genes and

diet, controls growth during childhood

People who produce little or no HGH

are abnormally short and may have

other related health problems. But

David has normal HGH levels. He is

short simply because his parents are

both healthy, short people.

But if David isnt sick, why does hi

doctor prescribe HGH? Where does

medicinal HGH come from? Is it safe?

What does this case say about sciencand society? As you read this chapter

look for clues about the nature of

science, the role of technology in our

modern world, and the relationship

between science and society. Then,

solve the mystery.

Never Stop Exploring Your World.

Finding the solution to the growth

hormone mystery is only the beginningTake a video field trip with the ecogeek

of Untamed Science to see where this

mystery leads.

These paleontologistsbiologists who study ancientlifeare working to reconstruct the skeleton ofCarcharodontosaurus,a giant dinosaur that livedover 90 million years ago. By using scientific skillssuch as observation and inference, scientists canlearn how ancient animals lived. The huge teeth ofthis dinosaur are sharp and serrated like a knife,suited for eating meata lot of it!

The Science of Biolog

INSIDE: 1.1 What Is Science?

1.2 Science in Context 1.3 Studying Life


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Science as a Way of Knowing ien eScienceis an organizedway of gathering and analyzing evidence about the naturalworld. It is a way of observing, a way of thinking, and a wayof knowing about the world. In other words, science is aprocess,not a thing. The word sciencealso refers to the body ofknowledge that scientific studies have gathered over the years.

Several features make science different from other humanendeavors. First, science deals only with the natural world.Scientific endeavors never concern, in any way, supernatural

phenomena of any kind. Second, scientists collect and orga-nize information in an orderly way, looking for patterns andconnections among events. Third, scientists propose explana-tions that are based on evidence, not belief. Then they testthose explanations with more evidence.

The Goals of Science The scientific way of knowingincludes the view that the physical universe is a system com-posed of parts and processes that interact. From a scientificperspective, all objects in the universe, and all interactionsamong those objects, are governed by universal natural laws.

The same natural laws apply whether the objects or events arelarge or small.Aristotle and other Greek philosophers were among the first to

try to view the universe in this way. They aimed to explain the worldaround them in terms of events and processes they could observe.Modern scientists continue that tradition. One goal of scienceis to provide natural explanations for events in the natural world.Science also aims to use those explanations to understand patternsin nature and to make useful predictions about natural events.

Science, Change, and Uncertainty Over the centuries, scientistshave gathered an enormous amount of information about the natu-

ral world. Scientific knowledge helps us cure diseases, place satellitesin orbit, and send instantaneous electronic communications. Yet,despite all we know, much of nature remains a mystery. It is a mysterybecause science never stands still; almost every major scientific dis-covery raises more questions than it answers. Often, research yieldssurprises that point future studies in new and unexpected directions.This constant change doesnt mean science has failed. On the contrary,it shows that science continues to advance.

Thats why learning about science means more than just under-standing what we know. It also means understanding what we dontknow. You may be surprised to hear this, but science rarely proves

anything in absolute terms. Scientists aim for the best understandingof the natural world that current methods can reveal. Uncertainty ispart of the scientific process and part of what makes science excit-ing! Happily, as youll learn in later chapters, science has allowed usto build enough understanding to make useful predictions about thenatural world.

In Your Notebook Explain in your own words why there isuncertainty in science.

FIGURE 12 Science in ActionThese marine scientists arerecording information as theystudy whales in Alaska.

BUILDVocabularyWORD ORIGINS The words ien e

science

derives from the Latinword scientia,which meansknowledge. Science represenknowledge that has been gatheover time.



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Scientific Methodology:The Heart of Science

What procedures are at the core of scientific methodology?

You might think that science is a mysterious process, used only bycertain people under special circumstances. But thats not true,because you use scientific thinking all the time. Suppose your familyscar wont start. What do you do? You use what you know about cars

to come up with ideas to test. At first, you might think the battery isdead. So you test that idea by turning the key in the ignition. If thestarter motor works but the engine doesnt start, you reject the dead-battery idea. You might guess next that the car is out of gas. A glanceat the fuel gauge tests that idea. Again and again, you apply scientificthinking until the problem is solvedor until you run out of ideas andcall a mechanic!

Scientists approach research in pretty much the same way. Thereisnt any single, cut-and-dried scientific method. There is, however, ageneral style of investigation that we can call scientific methodology.

Scientific methodology involves observing and asking

questions, making inferences and forming hypotheses, conductingcontrolled experiments, collecting and analyzing data, and drawingconclusions. Figure 13shows how one research team used scientificmethodology in its study of New England salt marshes.

Observing and Asking Questions Scientific investigationsbegin with

observationobservation,the act of noticing and describing events orprocesses in a careful, orderly way. Of course, scientific observationinvolves more than just looking at things. A good scientist can, as thephilosopher Arthur Schopenhauer put it, Think something thatnobody has thought yet, while looking at something that everybodysees. That kind of observation leads to questions that no one has

asked before.

Location A Location B

OBSERVING AND ASKING QUESTIONS INFERRING AND HYPOTHESIZING

FIGURE 13 Salt MarshExperiment Salt marshes are coastalenvironments often found whererivers meet the sea. Researchersmade an interesting observation onthe way marsh grasses grow. Then,

they applied scientific methodologyto answer questions that arose fromtheir observation.

Researchers observed that marsh grass grows tallerin some places than others. This observation led toa question: Why do marsh grasses grow to differentheights in different places?

The researchers inferred that something limits grass growthin some places. It could be any environmental factortemperature, sunlight, water, or nutrients. Based on theirknowledge of salt marshes, they proposed a hypothesis:Marsh grass growth is limited by available nitrogen.

More nitrogen?

6 Lesson 1.1 Art in Motion InterActive Art


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DESIGNING CONTROLLED EXPERIMENTS

N

ControlGroup

ExperimentalGroup

No nitrogen added Nitrogen added

Inferring and Forming a Hypothesis After posing questions, sci-entists use further observations to make inferences. An inferenceinferenceis alogical interpretation based on what scientists already know. Inference,combined with a creative imagination, can lead to a hypothesis. Ahypothesishypothesisis a scientific explanation for a set of observations thatcan be tested in ways that support or reject it.

Designing Controlled Experiments Testing a scientific hypothesisoften involves designing an experiment that keeps track of various fac-

tors that can change, or variables. Examples of variables include tem-perature, light, time, and availability of nutrients. Whenever possible,a hypothesis should be tested by an experiment in which only onevariable is changed. All other variables should be kept unchanged, orcontrolled. This type of experiment is called a controlled experiment.controlled experiment.

Controlling Variables Why is it important to control variables?The reason is that if several variables are changed in the experiment,researchers cant easily tell which variable is responsible for any resultsthey observe. The variable that is deliberately changed is called theindependent variableindependent variable(also called the manipulated variable). Thevariable that is observed and that changes in response to the inde-pendent variable is called the dependent variabledependent variable(also called theresponding variable).

Control and Experimental Groups Typically, an experiment isdivided into control and experimental groups. A controlcontrolgroupgroupisexposed to the same conditions as the experimental group except forone independent variable. Scientists always try to reproduce or repli-cate their observations. Therefore, they set up several sets of controland experimental groups, rather than just a single pair.

In Your Notebook What is the difference between an observationand an inference? List three examples of each.

The researchers selected similar plots of marsh grass.All plots had similar plant density, soil type, inputof freshwater, and height above average tide level.The plots were divided into control and experimentalgroups.

The researchers added nitrogen fertilizer (theindependent variable) to the experimental plots.They then observed the growth of marsh grass(the dependent variable) in both experimental andcontrol plots.



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Height of Grasses

Control

Time (weeks)

Heigh

t(m)

N

Collecting and Analyzing Data Scientists make detailedrecords of experimental observations, gathering informationcalled d tdata.There are two main types of data. Quantitativedata are numbers obtained by counting or measuring. In themarsh grass experiment, quantitative data could include thenumber of plants per plot, the length, width, and weight ofeach blade of grass, and so on. Qualitative data are descriptiveand involve characteristics that cannot usually be counted.Qualitative data in the marsh grass experiment might includenotes about foreign objects in the sample plots or informationon whether the grass was growing upright or sideways.

Research Tools Scientists choose appropriate tools for col-lecting and analyzing data. The tools may range from simpledevices such as metersticks and calculators to sophisticatedequipment such as machines that measure nitrogen contentin plants and soil. Charts and graphs are also tools that helpscientists organize their data. In the past, data were recordedby hand, often in notebooks or personal journals. Today,researchers typically enter data into computers, which make

organizing and analyzing data easier. Many kinds of data arenow gathered directly by computer-controlled equipment.

Sources of Error Researchers must be careful to avoiderrors in data collection and analysis. Tools used to measurethe size and weight of marsh grasses, for example, have lim-ited accuracy. Data analysis and sample size must be chosencarefully. In medical studies, for example, both experimentaland control groups should be quite large. Why? Because thereis always variation among individuals in control and experi-mental groups. The larger the sample size, the more reliablyresearchers can analyze that variation and evaluate the diffe-

rences between experimental and control groups.

COLLECTING AND ANALYZING DATA DRAWING CONCLUSIONS

8 Chapter 1 Lesson 1

ControlGroup

ExperimentalGroup

Describe a controlledexperiment that canbe designed to test thehypothesis that extraHGH helps childrengrow taller. Whatethical issues can

you imagine inactually carryingout such a study?

The researchers sampled all the plots throughout thegrowing season. They measured growth rates andplant sizes, and analyzed the chemical compositionof living leaves.

Data from all plots were compared and evaluatedby statistical tests. Data analysis confirmed that marshgrasses in experimental plots with additional nitrogendid, in fact, grow taller and larger than controls.The hypothesis and its predictions were supported.

FIGURE 13 Continued



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FIGURE 14 Revising HypothesesDuring the course of an investigation,hypotheses may have to be revised aexperiments redone several times.

Review Key Concepts

1. a.Review What is science? b.Explain What kinds of understandings does

science contribute about the natural world?

c.Form an Opinion Do you think that sci-

entists will ever run out of things to study?Explain your reasoning.

2. a.Review What does scientific methodologyinvolve?

b.Explain Why are hypotheses so importantto controlled experiments?

Creative Writing3. A few hundred years ago, observations seemed

to indicate that some living things could justsuddenly appear: maggots showed up on meatmice were found on grain; and beetles turned

up on cow dung. Those observations led to thincorrect idea of spontaneous generationthnotion that life could arise from nonlivingmatter. Write a paragraph for a history maga-zine evaluating the spontaneous generationhypothesis. Why did it seem logical at the timeWhat evidence was overlooked or ignored?

Lesson 1.1 Self-Test Lesson Assessment Art Review

Initialobservation

Hypothesis

Hypothesis not supported

Experiment

Interpretation

Observation andanalysis of data

Newhypothesis

Newexperiment

Newobservation

Final hypothesissupported

Drawing Conclusions Scientists use experimental data asevidence to support, refute, or revise the hypothesis being tested,and to draw a valid conclusion. Hypotheses are often not fullysupported or refuted by one set of experiments. Rather, newdata may indicate that the researchers have the right general ideabut are wrong about a few particulars. In that case, the originalhypothesis is reevaluated and revised; new predictions are made,and new experiments are designed. Those new experimentsmight suggest changes in the experimental treatment or bettercontrol of more variables. As shown in Figure 14,many circuitsaround this loop are often necessary before a final hypothesis issupported and conclusions can be drawn.

When Experiments Are Not Possible It is not always possibleto test a hypothesis with an experiment. In some of these cases,researchers devise hypotheses that can be tested by observations.Animal behavior researchers, for example, might want to learnhow animal groups interact in the wild. Investigating this kindof natural behavior requires field observations that disturb theanimals as little as possible. When researchers analyze data from

these observations, they may devise hypotheses that can be testedin different ways.

Sometimes, ethics prevents certain types of experimentsespecially on human subjects. Medical researchers who suspectthat a chemical causes cancer, for example, would not intention-ally expose people to it! Instead, they search for volunteers whohave already been exposed to the chemical. For controls, theystudy people who have not been exposed to the chemical. Theresearchers still try to control as many variables as possible.For example, they might exclude volunteers who have serioushealth problems or known genetic conditions. Medical research-

ers always try to study large groups of subjects so that individualgenetic differences do not produce misleading results.



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Explorationand

discovery

Scienceand

society

Communicatingresults

ScientificMethodology

Adapted from Understanding Science,UC Berkeley, Museum of Paleontology

Science in Context

Key Questions

What scientific attitudeshelp generate new ideas?

Why is peer reviewimportant?

What is a scientific theory?

What is the relationshipbetween science and society?

Vocabularytheory bias

Taking NotesPreview Visuals Before you read,study Figure 110.As you read,use the figure to describe the rolescience plays in society.

Exploration and Discovery:Where Ideas Come From

What scientific attitudes help generate new ideas?

Scientific methodologyis closelylinkedto exploration anddiscovery,as shown in Figure 15.Recallthat scientific methodologystarts withobservations andquestions. But where do those observations andques-tions come from in the first place? Theymaybe inspiredbyscientificattitudes, practicalproblems, andnew technology.

Scientific Attitudes Goodscientists share scientific attitudes, orhabitsofmind, that leadthem to exploration anddiscovery. Curiosity,skepticism, open-mindedness, and creativity help scientists generatenew ideas.

Curiosity A curious researcher, forexample, maylookat a salt

marsh andimmediatelyask, Whats that plant? Whyis it growinghere? Often, results from previous studies also sparkcuriosityand

leadto new questions.

Skepticism Goodscientists are skeptics, whichmeans that theyquestion existing ideas andhypothe-ses, andtheyrefuse to accept explanations without evi-dence. Scientists who disagree with hypotheses designexperiments to test them. Supporters ofhypothesesalso undertake rigorous testing oftheirideas to con-firm them andto address anyvalidquestions raised.

Open-Mindedness

Scientists must remain open-minded, meaning that theyare willing to accept dif-ferent ideas that maynot agree with theirhypothesis.

Creativity Researchers also needto thinkcreatively

to design experiments thatyieldaccurate data.

FIGURE 15 The Process of

Science As the arrows indicate,the different aspects of scienceare interconnectedmakingthe process of science dynamic,flexible, and unpredictable.

10 Lesson 1.2 Lesson Overview Lesson Notes

THINK ABOUT IT Scientific methodologyis the heart ofscience.But that vitalheart is onlypart ofthe fullbody ofscience. Scienceandscientists operate in the context ofthe scientific communityandsocietyat large.


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CuriositySurprising observationPersonal motivationPractical problemNew technology

Sharing dataand ideas

Makingobservations

Askingquestions

Exploring theliterature

Findinginspiration

Adapted from Understanding Science,UC Berkeley, Museum of Paleontology

Explorationand

discovery

Practical Problems Sometimes, ideas forscientific investigationsarise from practicalproblems. Salt marshes, forexample, playvitalroles in the lives ofmanyecologicallyandcommerciallyimportantorganisms, asyou willlearn in the next unit. Yet theyare underintensepressure from industrialandhousing development. Shouldmarshesbe protectedfrom development? Ifnew houses orfarms are locatednearsalt marshes, can theybe designedto protect the marshes? These

practicalquestions andissues inspire scientific questions, hypotheses,andexperiments.

The Role of Technology Technology, science, andsocietyare closelylinked. Discoveries in one fieldofscience mayleadto new technolo-gies. Those technologies, in turn, enable scientists in otherfields to asknew questions orto gatherdata in new ways. Forexample, the devel-opment ofnew portable, remote data-collecting equipment enablesfieldresearchers to monitorenvironmentalconditions aroundtheclock, in severallocations at once. This capabilityallows researchers topose andtest new hypotheses. Technologicaladvances can also havebig impacts on dailylife. In the fieldofgenetics andbiotechnology,

forinstance, it is now possible to mass-produce complex substancessuch as vitamins, antibiotics, andhormonesthat before were onlyavailable naturally.

In Your Notebook Describe a situation where you were skeptical ofa fact you had seen or heard.

FIGURE 17

Ideas FroPractical ProblemsPeople living on a strip land like this one in MuInlet, South Carolina, mface flooding and otherproblems.Pose Questions What asome scientific questionscan arise from a situatiolike this one?

FIGURE 16 Exploration andDiscovery Ideas in science canarise in many waysfrom simplecuriosity or from the need to solve particular problem. Scientists oftenbegin investigations by makingobservations, asking questions, talwith colleagues, and reading abouprevious experiments.

How does theability to produceartificial HGHimpact human life?

The Science of Biology


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Replicationof results

PublicationDiscussion with

colleagues

Feedback andpeer review

New ideas

Adapted from Understanding Science,

UC Berkeley, Museum of Paleontology

Communicatingresults

Communicating Results:Reviewing and Sharing Ideas

Why is peer review important?

Data collection andanalysis can be a long process. Scientists mayfocusintenselyon a single studyformonths orevenyears. Then, the excit-ing time comes when researchers communicate theirexperiments andobservations to the scientific community. Communication andshar-

ing ofideas are vitalto modern science.

Peer Review Scientists share theirfindings with the scientific com-munitybypublishing articles that have undergone peerreview. Inpeerreview, scientific papers are reviewedbyanonymous, indepen-dent experts. Publishing peer-reviewed articles in scientificjournals allows researchers to share ideas and to test and evaluateeach others work.Scientific articles are like high-poweredversions ofyourhigh schoollab reports. Theycontain details about experimentalconditions, controls, data, analysis, andconclusions. Reviewers readthem looking foroversights, unfairinfluences, fraud, ormistakes in

techniques orreasoning. Theyprovide expert assessment ofthe workto ensure that the highest standards ofqualityare met. Peerreviewdoes not guarantee that a piece ofworkis correct, but it does certifythat the workmeets standards set bythe scientific community.

Sharing Knowledge and New Ideas Once research has been pub-lished, it enters the dynamic marketplace ofscientific ideas, as shownin Figure 18.How do new findings fit into existing scientific under-standing? Perhaps theysparknew questions. Forexample, the find-ing that growth ofsalt marsh grasses is limitedbyavailable nitrogensuggests otherhypotheses: Is the growth ofotherplants in the samehabitat also limitedbynitrogen? What about the growth ofdifferent

plants in similarenvironments, such as the mangrove swampshownin Figure 19?Each ofthese logicalandimportant questions leads tonew hypotheses that must be independentlyconfirmedbycontrolledexperiments.

In Your Notebook Predict what might happen if an article ispublished without undergoing peer review.

FIGURE 19 MangroveSwampIn tropical areas,mangrove swamps serve asthe ecological equivalentsof temperate salt marshes.The results of the salt marshexperiment suggest that nitrogenmight be a limiting nutrient formangroves and other plants inthese similar habitats.Design an Experiment Howwould you test this hypothesis?

FIGURE 18 Communicating ResultsCommunication is an important partof science. Scientists review andevaluate one anothers work to ensureaccuracy. Results from one study maylead to new ideas and further studies.



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Scientific TheoriesWhat is a scientific theory?

Evidence from manyscientific studies maysupport severalrelatedhypotheses in a waythat inspires researchers to propose a scientifict orytheorythat ties those hypotheses together. Asyou readthis book,youwilloften come across terms that willbe new toyou because theyareusedonlyin science. But the wordtheoryis usedboth in science andin everydaylife. It is important to understandthat the meaning yougive the wordtheoryin dailylife is verydifferent from its meaningin science. Whenyou say, I have a theory,you maymean, I havea hunch. When a friendsays, Thats just a theory she maymean,People arent too certain about that idea. In those same situations, ascientist wouldprobablyuse the wordhypothesis.But when scientists

talkabout gravitationaltheoryorevolutionarytheory, theymeansomething verydifferent from hunchorhypothesis.

In science, the word theoryapplies to a well-testedexplanation that unifies a broad range of observations andhypotheses and that enables scientists to make accurate predictionsabout new situations.Charles Darwins earlyobservations andhypotheses about change overtime in nature, forexample, grew andexpandedforyears before he collectedthem into a theoryofevolutionbynaturalselection. Today, evolutionarytheoryis the centralorgani-zing principle ofallbiologicalandbiomedicalscience. It makes such awide range ofpredictions about organismsfrom bacteria to whales

to humansthat it is mentionedthroughout this book.A usefultheorythat has been thoroughlytestedandsupported

bymanylines ofevidence maybecome theom n nt

dominant view amongthe majorityofscientists, but no theoryis consideredabsolute truth.Science is always changing; as new evidence is uncovered, a theorymaybe revisedorreplacedbya more usefulexplanation.

Replicating Procedures1 Working with a partnerbehinda screen, assemble ten

blocks into an unusualstructure. Write directions thatothers can use to replicate that structure without seeing it.

2 Exchange directions with anotherteam. Replicate theteams structure byfollowing its directions.

3 Compare each replicatedstructure to the original.Identifywhich parts ofthe directions were clearandaccurate, andwhich were unclearormisleading.

Analyze and Conclude1. Evaluate How couldyou havewritten betterdirections?

2. Infer Whyis it important thatscientists write procedures that canbe replicated?

BUILDVocabularyACADEMIC WORDS The adjectomin ntdominantmeans having the m

authority or influence. Afteran idea has been thoroughlytested, confirmed repeatedly,and is accepted by the majorityof scientists, it may becomethe dominant explanation for aparticular phenomenon.



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not dropped

FPO

Science and SocietyWhat is the relationship between science and society?

Make a list of health-related things that you need to understand toprotect your life and the lives of others close to you. Your list mayinclude drugs and alcohol, smoking and lung disease, AIDS, cancer,and heart disease. Other topics focus on social issues and the environ-ment. How much of the information in your genes should be keptprivate? Should communities produce electricity using fossil fuels,nuclear power, solar power, wind power, or hydroelectric dams? Howshould chemical wastes be disposed of?

All these questions require scientific information to answer, andmany have inspired important research. But none of these questionscan be answered by science alone. These questions involve the society

in which we live, our economy, and our lawsand moral principles. Using scienceinvolves understanding its context in societyand its limitations. Figure 110 shows therole science plays in society.

Science, Ethics, and Morality When scien-tists explain why something happens, theirexplanation involves only natural phenomena.Pure science does not include ethical or moralviewpoints. For example, biologists try toexplain in scientific terms what life is, how lifeoperates, and how life has changed over time.But science cannot answer questions aboutwhy life exists or what the meaning of life is.

Similarly, science can tell us how technology and scientific knowledgecan be applied but not whether it should be applied in particular ways.

Remember these limitations when you study and evaluate science.Avoiding Bias The way that science is applied in society can beaffected by bias. A

i sbiasis a particular preference or point of view thatis personal, rather than scientific. Examples of biases include personaltaste, preferences for someone or something, and societal standardsof beauty.

Science aims to be objective, but scientists are human, too. Theyhave likes, dislikes, and occasional biases. So, it shouldnt surprise youto discover that scientific data can be misinterpreted or misappliedby scientists who want to prove a particular point. Recommendationsmade by scientists with personal biases may or may not be in the pub-

lic interest. But if enough of us understand science, we can help makecertain that science is applied in ways that benefit humanity.

Addresssocietal issues

Solve everydayproblems

Satisfycuriosity

Buildknowledge

Developtechnology

Informpolicy

Scienceand

society

Adaptedfrom Understanding Science,

UC Berkeley, Museum ofPaleontology

FIGURE 110 Science and SocietyScience both influences society and isinfluenced by society. The researcherbelow tests shellfish for toxins thatcan poison humans. Form anOpinion Should shellfish be routinelyscreened for toxins?



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Understanding and Using Science Science will keepchanging as long as humans keep wondering about nature.We invite you to join us in that wonder and exploration as

you read this book. Think of this text, not as an encyclopedia,but as a users guide to the study of life. Dont just memo-rize todays scientific facts and ideas. And please dont believethem! Instead, try to understandhow scientists developedthose ideas. Try to see the thinking behind experiments wedescribe. Try to pose the kinds of questions scientists ask.

If you learn to think as scientists think, you will understandthe process of science and be comfortable in a world that willkeep changing throughout your life. Understanding sciencewill help you make complex decisions that also involve cul-tural customs, values, and ethical standards.

Furthermore, understanding biology will help you realizethat we humans can predict the consequences of our actionsand take an active role in directing our future and that ofour planet. In our society, scientists make recommenda-tions about big public policy decisions, but they dontmake the decisions. Who makes the decisions? Citizens

of our democracy do. In a few years, you will be able toexercise the rights of a voting citizen, influencing publicpolicy by the ballots you cast and the messages you sendpublic officials. Thats why it is important that you under-stand how science works and appreciate both the power andthe limitations of science.

FIGURE 111 Using Sciencein Everyday LifeThese studentvolunteers are planting mangrovesaplings as part of a mangroverestoration project.

Review Key Concepts1. a.Review List the attitudes that lead scien-

tists to explore and discover.

b.Explain What does it mean to describe ascientist as skeptical? Why is skepticism animportant quality in a scientist?

2. a.Review What is peer review? b.Apply Concepts An advertisement claims

that studies of a new sports drink show itboosts energy. You discover that none ofthe study results have been peer-reviewed.

What would you tell consumers who areconsidering buying this product?

3. a.Review What is a scientific theory? b.Compare and Contrast How does use

of the word theorydiffer in science and indaily life?

4. a.Review How is the use of science related toits context in society? b.Explain Describe some of the limitations

of science.

c.Apply Concepts A study shows that a newpesticide is safe for use on food crops. Theresearcher who conducted the study worksfor the pesticide company. What potentialbiases may have affected the study?

Science as a Way of Knowing5. Explain in your own words why science is

considered a way of knowing.


Lesson 1.2 Self-Test Lesson Assessment


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16 Biology and Society

iologyBiology&ocietySociety

Biology plays a major role in the research, develop-ment, and production of food, medicine, and otherconsumer items. Companies that make these itemsprofit by selling reliable and useful products in themarketplace. For example, the plastics industry pro-vides countless products for everyday use.

But sometimes questions arise concerning productsafety. Bisphenol-A (BPA), for instance, is a chemicalfound in hard plastics. Those plastics are used to makebaby bottles, reusable water bottles, and the liningsof many food and soft drink cans. Is BPA safe? Thistype of question can be posed as a scientific hypothesisto be tested. But who does the testing? Who funds thestudies and analyzes the results?

Ideally, independent scientists test products forsafety and usefulness. That way, the people who gatherand analyze data can remain objectivethey havenothing to gain by exaggerating the positive effectsof products and nothing to lose by stating any risks.However, scientists are often hired by private com-

panies to develop or test their products.Often, test results are clear: A product is safe or

it isnt. Based on these results, the Food and DrugAdministration (FDA) or another governmentagency makes recommendations to protect and pro-mote public health. Sometimes, though, results aretough to interpret.

More than 100 studies have been done on BPAsome funded by the government, some funded by theplastics industry. Most of the independent studiesfound that low doses of BPA could have negative

health effects on laboratory animals. A few studies,mostly funded by the plastics industry, concludedthat BPA is safe. In this case, the FDA ultimatelydeclared BPA to be safe. When the issue of BPA safetyhit the mass media, government investigations began.So, who should sponsor product safety studies?

The ViewpointsIndependent OrganizationsShould Fund Safety StudiesScientists performing safety studiesshould have no affiliation with privateindustries, because conflict of inter-est seems unavoidable. A company,such as a BPA manufacturer, would

naturally benefit if its product is declared to be safe.Rather, safety tests should be funded by indepen-dent organizations such as universities and govern-ment agencies, which should be as independent aspossible. This way, recommendations for publichealth can remain free of biases.

Private Industries Should Fund Safety StudiesThere are an awful lot of products out there! Whowould pay scientists to test all those products? Thereare simply too many potentially useful and valuableproducts being developed by private industry for

the government to keep track of and test adequatelywith public funds. It is in a companys best interestto produce safe products, so it would be inclined tomaintain high standards and perform rigorous tests.

Who Should Fund Product Safety Studies?

Research and Decide

1. Analyze the Viewpoints To make aninformed decision, research the current status ofthe controversy over BPA by using the Internetand other resources. Compare this situation with

the history of safety studies on cigarette smokeand the chemical Tefl on.

2. Form an Opinion Should private indus-tries be able to pay scientists to perform theirproduct safety studies? How would you deal withthe issue of potential bias in interpreting results?


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THE CHARACTERISTICS

OF LIVING THINGSFIGURE 113

Apple trees share certaincharacteristics with other living things.Compare and Contrast How are the apple treeand the grass growing below similar? How arethey different?

Living things are based on auniversal genetic code.All organismsstore the complex information they need to

live, grow, and reproduce in a genetic codewritten in a molecule called DNADNA. Thatinformation is copied and passed from par-ent to offspring. With a few minor varia-tions, lifes genetic code is almost identicalin every organism on Earth.

The growth, form, and structure of an appletree are determined by information in its DNA.

Living things grow and

develop.Every organism hasa particular pattern of growthand development. Duringdevelopment, a single fertilizedegg divides again and again. Asthese cells divide, they differen-

tiate, which means theybegin to look differentfrom one another andto perform differentfunctions.

An apple treedevelops from a tinyseed.

Living things respond

to their environment.Organisms detect andrespond to stimuli from theirenvironment. A stimulusstimulusis asignal to which an organismresponds.

Some plants can produceunsavory chemicals to wardoff caterpillars thatfeed on theirleaves.



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Whats in a Diet?

The circle graph shows thediet of the siamang gibbon,a type of ape found in the

rainforests of Southeast Asia.

Analyze and Conclude1. Interpret Graphs Whichplant parts do siamangs relyon most as a source of theirmatter and energy?

2. Predict How wouldsiamangs be affected if therainforests they live in werecut down?

Big Ideas in Biology

What are the central themes of biology?

The units of this book seem to cover different subjects. But well letyou in on a secret: Thats not how biology works. All biological sci-ences are tied together by themes and methods of study that cut acrossdisciplines. These big ideas overlap and interlock, and crop up againand again throughout the book. Youll also notice that several of thesebig ideas overlap with the characteristics of life or the nature of science.

The study of biology revolves around several interlockingbig ideas: The cellular basis of life; information and heredity; matterand energy; growth, development, and reproduction; homeostasis;evolution; structure and function; unity and diversity of life;interdependence in nature; and science as a way of knowing.

Cellular Basis of Life Living things are made of cells.Many living things consist of only a single cell; they are called unicel-lular organisms. Plants and animals are multicellular. Cells in multi-cellular organisms display many different sizes, shapes, and functions.The human body contains 200 or more different cell types.

Information and Heredity Living things are basedon a universal genetic code. The information coded in DNA forms anunbroken chain that stretches back roughly 3.5 billion years. Yet, theDNA inside your cells right now can influence your futureyour riskof getting cancer, the amount of cholesterol in your blood, and thecolor of your childrens hair.

Matter and Energy Living things obtain and usematerial and energy. Life requires matter that serves as nutrients tobuild body structures, and energy that fuels lifes processes. Someorganisms, such as plants, obtain energy from sunlight and take up

nutrients from air, water, and soil. Other organisms, including mostanimals, eat plants or other animals to obtain both nutrients andenergy. The need for matter and energy link all living things on Earthin a web of interdependent relationships.

Growth, Development, and Reproduction All liv-ing things reproduce. Newly produced individuals are virtually alwayssmaller than adults, so they grow and develop as they mature. Duringgrowth and development, generalized cells typically become more andmore different and specialized for particular functions. Specializedcells build tissues, such as brains, muscles, and digestive organs, thatserve various functions.

Homeostasis Living things maintain a relatively stableinternal environment, a process known as homeostasis. For mostorganisms, any breakdown of homeostasis may have serious or evenfatal consequences.

Leaves:50%

Flowers, buds,and insects: 10%

Fruits:40%

In Your Notebook Describe what happens at the cellular level as ababy grows and develops.



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Evolution Taken as a group, living things evolve.Evolutionary change links all forms of life to a common origin morethan 3.5 billion years ago. Evidence of this shared history is foundin all aspects of living and fossil organisms, from physical featuresto structures of proteins to sequences of information in DNA.Evolutionary theory is the central organizing principle of all biologicaland biomedical sciences.

Structure and Function

Each major group of organ-isms has evolved its own particular body part tool kit,a collectionof structures that have evolved in ways that make particular functionspossible. From capturing food to digesting it, and from reproducingto breathing, organisms use structures that have evolved into differentforms as species have adapted to life in different environments. Thestructures of wings, for example, enable birds and insects to fly. Thestructures of legs enable horses to gallop and kangaroos to hop.

Unity and Diversity of Life Although life takes analmost unbelievable variety of forms, all living things are fundamen-tally similar at the molecular level. All organisms are composed of a

common set of carbon-based molecules, store information in a com-mon genetic code, and use proteins to build their structures and carryout their functions. One great contribution of evolutionary theory isthat it explains both this unity of life and its diversity.

Interdependence in Nature All forms of life onEarth are connected into a

iospherebiosphere,which literally means livingplanet. Within the biosphere, organisms are linked to one anotherand to the land, water, and air around them. Relationships betweenorganisms and their environments depend on the cycling of matterand the flow of energy. Human life and the economies of humansocieties also require matter and energy, so human life dependsdirectly on nature.

Science as a Way of KnowingScience is not a list of facts, but a way of knowing.The job of science is to use observations, questions, andexperiments to explain the natural world in terms ofnatural forces and events. Successful scientific researchreveals rules and patterns that can explain and predictat least some events in nature. Science enables us totake actions that affect events in the world around us.To make certain that scientific knowledge is used for

the benefit of society, all of us must understand thenature of scienceits strengths, its limitations, andits interactions with our culture.

What human valuesor biases are involvedin the case of givingHGH to healthychildren? Whatrole doesscience play inthis case?

FIGURE 114 Different But SimilarThe colorful keel-billed toucan is clearly different fromthe plant on which it perches. Yet, the two organismsare fundamentally similar at the molecular level. Unityand diversity of life is an important theme in biology.



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Global Ecology Life on Earth is shaped by weatherpatterns and processes in the atmosphere so large thatwe are just beginning to understand them. We are alsolearning that activities of living organismsincludinghumansprofoundly affect both the atmosphere andclimate. Humans now move more matter and use moreenergy than any other multicellular species on Earth.Global ecological studies, aided by satellite technologyand supercomputers, are enabling us to learn about ourglobal impact, which affects all life on Earth.

An ecologist studies lichens on Douglas fir. Many lichensare extremely sensitive to nitrogen- and sulfur-based airpollution. Thus, researchers often monitor lichens in effortsto study the effects of air pollution on forest health.

Fields of Biology

How do different fields of biology differ intheir approach to studying life?

Living systems range from groups of molecules thatmake up cells to collections of organisms that makeup the biosphere. Biology includes manyoverlapping fields that use different tools to studylife from the level of molecules to the entire planet.Heres a peek into a few of the smallest and largestbranches of biology.



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Biotechnology This field, created by the molecularrevolution, is based on our ability to edit and rewritethe genetic codein a sense, redesigning the livingworld to order. We may soon learn to correct or replacedamaged genes that cause inherited diseases. Otherresearch seeks to genetically engineer bacteria to cleanup toxic wastes. Biotechnology also raises enormousethical, legal, and social questions. Dare we tamper withthe fundamental biological information that makes ushuman?

A plant biologist analyzes genetically modified riceplants.

Building the Tree of Life Biologists have discovered andidentified roughly 1.8 million different kinds of livingorganisms. That may seem like an incredible number,but researchers estimate that somewhere between 2and 100 million more forms of life are waiting to bediscovered around the globefrom caves deep beneaththe surface, to tropical rainforests, to coral reefs and thedepths of the sea. Identifying and cataloguing all theselife forms is enough work by itself, but biologists aim todo much more. They want to combine the latest geneticinformation with computer technology to organize allliving things into a single universal Tree of All Lifeand put the results on the Web in a form that anyone canaccess.

A paleontologist studies signs of ancient lifefossilized dinosaur dung!

Genomics and Molecular BiologyThese fields focuson studies of DNA and other molecules inside cells. The

molecular revolution of the 1980s created the field ofgenomics, which is now looking at the entire sets of DNAcode contained in a wide range of organisms. Ever-more-powerful computer analyses enable researchersto compare vast databases of genetic information in afascinating search for keys to the mysteries of growth,development, aging, cancer, and the history of life onEarth.

A molecular biologist analyzes a DNA sequence.

Ecology and Evolution of Infectious DiseasesHIV, bird flu, and drug-resistant bacteria seem to haveappeared out of nowhere, but the science behindtheir stories shows that relationships between hostsand pathogens are dynamic and constantly changing.Organisms that cause human disease have their own

ecology, which involves our bodies, medicines wetake, and our interactions with each other and theenvironment. Over time, disease-causing organismsengage in an evolutionary arms race with humansthat creates constant challenges to public health aroundthe world. Understanding these interactions is crucial tosafeguarding our future.

A wildlife biologist studies a group of wild geladababoons. Pathogens in wild animal populations mayevolve in ways that enable them to infect humans.


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Common Metric Units

1 kilogram (kg) = 1000 grams (g)1 gram = 1000 milligrams (mg)1000 kilograms = 1 metric ton (t)

0C = freezing point of water

100C = boiling point of water

Mass

1 meter (m) = 100 centimeters (cm)1 meter = 1000 millimeters (mm)1000 meters = 1 kilometer (km)

1 liter (L) = 1000 milliliters (mL)

1 liter = 1000 cubic centimeters (cm)

Length

TemperatureVolume

Performing Biological Investigations

How is the metric system important in science?

During your study of biology, you will have the opportunity toperform scientific investigations. Biologists, like other scientists, relyon a common system of measurement and practice safety procedureswhen conducting studies. As you study and experiment, you willbecome familiar with scientific measurement and safety procedures.

Scientific Measurement Because researchers need to replicateone anothers experiments, and because many experiments involvegathering quantitative data, scientists need a common system ofmeasurement. Most scientists use the metric system whencollecting data and performing experiments.The metric system isa decimal system of measurement whose units are based on certainphysical standards and are scaled on multiples of 10. A revised ver-sion of the original metric system is called the International Systemof Units, or SI. The abbreviation SIcomes from the French Le SystmeInternational dUnits.

Because the metric system is based on multiples of 10, it is easy to

use. Notice in Figure 115how the basic unit of length, the meter, canbe multiplied or divided to measureobjects and distances much larger orsmaller than a meter. The same processcan be used when measuring volumeand mass. You can learn more aboutthe metric system in Appendix B.

BUILDVocabularyPREFIXES The SI prefix milli-means thousandth. Therefore,1 millimeter is one-thousandth ofa meter, and 1 milligram isone-thousandth of a gram.

FIGURE 115 TheMetric System Scientistsusually use the metricsystem in their work.This system is easy touse because it is based

on multiples of 10. Inthe photo, biologists inAlaska weigh a smallpolar bear. Predict Whatunit of measurementwould you use to expressthe bears mass?



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Safety Scientists working in a laboratory or in the field aretrained to use safe procedures when carrying out investiga-tions. Laboratory work may involve flames or heating ele-ments, electricity, chemicals, hot liquids, sharp instruments,and breakable glassware. Laboratory work and fieldworkmay involve contact with living or dead organismsnot justpotentially poisonous plants and venomous animals but also

disease-carrying mosquitoes and water contaminated withdangerous microorganisms.Whenever you work in your biology laboratory, you must

follow safe practices as well. Careful preparation is the keyto staying safe during scientific activities. Before performingany activity in this course, study the safety rules in AppendixB. Before you start each activity, read all the steps and makesure that you understand the entire procedure, including anysafety precautions.

The single most important safety rule is to always followyour teachers instructions and directions in this textbook.Any time you are in doubt about any part of an activity, ask

your teacher for an explanation. And because you may comein contact with organisms you cannot see, it is essential that

you wash your hands thoroughly after every scientific activity.Remember that you are responsible for your own safety andthat of your teacher and classmates. If you are handling liveanimals, you are responsible for their safety too.

Review Key Concepts1. a.Review List the characteristics that

define life.

b.Applying Concepts Suppose you feel hungry, soyou reach for a plum you see in a fruit bowl. Explainhow both external and internal stimuli are involvedin your action.

2. a.Review What are the themes in biology thatcome up again and again?

b.Predict Suppose you discover a new organism.What would you expect to see if you studied it

under a microscope?3. a.Review At what levels do biologists

study life?

b.Classify A researcher studies why frogs are disap-pearing in the wild. What field of biology does theresearch fall into?

Lesson 1.3 Data Analysis Self-Test Lesson Assessment

FIGURE 116 Science SafetyWearing appropriate protectivegear is important while working in laboratory.

4. a.Review Why do scientists use acommon system of measurement? b.Relate Cause and Effect Sup-

pose two scientists are tryingto perform an experiment thatinvolves dangerous chemicals. Howmight their safety be affected by notusing a common measurement?

5. In an experiment, you need 250

grams of potting soil for each of 10plant samples. How many kilo-grams of soil in total do you need?



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GUIDED INQUIRY

Pre-Lab: Using a Microscope to Estimate Size

Problem How can you use a microscope to esti-mate the size of an object?

Materials compound microscope, transparent15-cm plastic ruler, prepared slide of plant root orstem, prepared slide of bacteria

Lab Manual Chapter 1 Lab

Skills Focus Observe, Measure, Calculate, Predict

Connect to the Science provides away of knowing the world. The use of technology togather data is a central part of modern science. In biol-ogy, the compound microscope is a vital tool. With amicroscope, you can observe objects that are too tinyto see with the unaided eye. These objects include cells,which are the basis for all life.

In this lab, you will explore another important useof the microscope. You will use the microscope to esti-mate the size of cells.

Background Questionsa.Explain How did the invention of the microscope

help scientists know the natural world?

b.Explain How can a microscope help a scientist usescientific methodology?

c. Infer List one important fact about life that scien-tists would not know without microscopes. Hint:Review the characteristics of living things.

Pre-Lab QuestionsPreview the procedure in the lab manual.

1.Review Which lens provides more magnificationa low-power lens or a high-power lens? Which lensprovides the larger field of view?

2.Use Analogies A photographer may take wideviews and close-ups of the same scene. How are theseviews similar to the low-power and high-power lenseson a microscope? What is an advantage of each view?

3.Calculate Eight cells fit across a field of view of160 m. What is the width of each cell?

4.Predict Which cell do you think will be larger, theplant cell or the bacterial cell? Give a reason for

your answer.

Chapter 1

Visit Chapter 1 online to test yourself on chaptercontent and to find activities to help you learn.

Untamed Science Video Be prepared for somesurprise answers as the Untamed Science crew hit thestreets to ask people basic questions about science andbiology.

Art in Motion Learn about the steps scientists use tosolve problems. Change the variables, and watch whathappens!

Art Review Review your understanding of the varioussteps of experimental processes.

InterActive Art Design your own experiment to testRedis and Pasteurs spontaneous generation experiments.

Data Analysis Investigate the different strategiesscientists use for measurement.

26 Chapter 1 Pre-Lab


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Study GuideScience as a Way of Knowing

By applying scientific methodology, biologists can findanswers to questions that arise in the study of life.

1 11.1What Is Science?One goal of science is to provide natural expla-

nations for events in the natural world. Science alsoaims to use those explanations to understand pat-terns in nature and to make useful predictions aboutnatural events.

Scientific methodology involves observing andasking questions, making inferences and forminghypotheses, conducting controlled experiments, col-lecting and analyzing data, and drawing conclusions.

science (5) independent variable (7)observation (6) dependent variable (7)inference (7) control group (7)hypothesis (7) data (8)controlled experiment (7)

1 21.2 Science in Context

Curiosity, skepticism, open-mindedness, andcreativity help scientists generate new ideas.

Publishing peer-reviewed articles in scientific

journals allows researchers to share ideas and to testand evaluate each others work.

In science, the word theoryapplies to a well-tested explanation that unifies a broad range ofobservations and hypotheses and that enables sci-entists to make accurate predictions about newsituations.

Using science involves understanding its contextin society and its limitations.

theory (13)

bias (14)

1 31.3 Studying LifeLiving things are made up of units called cell

are based on a universal genetic code, obtain and materials and energy, grow and develop, reproduc

respond to their environment, maintain a stableinternal environment, and change over time.

The study of biology revolves around severalinterlocking big ideas: the cellular basis of life; infmation and heredity; matter and energy; growth,development, and reproduction; homeostasis; evotion; structure and function; unity and diversity olife; interdependence in nature; and science as a wof knowing.

Biology includes many overlapping fields thause different tools to study life from the level of m

ecules to the entire planet.

Most scientists use the metric system when clecting data and performing experiments.

biology (17) asexual reproduction (1DNA (18) homeostasis (19)stimulus (18) metabolism (19)sexual reproduction (19) biosphere (21)

Think Visually Using the information in thischapter, complete the following concept map:

11

Scientists

1

2

Observations

Inferences Questions

can lead to

can be tested by

Controlledexperiments

3

make

Chapter 1 Crossword Chapter Assessment


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1 11.1What Is Science?

Understand Key Concepts

1. Which of the following statements about the image

shown below is NOT an observation? a.The insect has three legs on the left side. b. The insect has a pattern on its back. c. The insects pattern shows that it is poisonous. d. The insect is green, white, and black.

2. The statement The worm is 2 centimeters longis a(n)

a.observation. c. inference. b. theory. d. hypothesis.

3. An inference is a.the same as an observation. b. a logical interpretation of an observation. c. a statement involving numbers. d. a way to avoid bias.

4. To be useful in science, a hypothesismust be

a.measurable. c. testable. b. observable. d. correct.

5. Which of the following statements about a con-trolled experiment is true?

a.All the variables must be kept the same. b. Only one variable is tested at a time. c.Everything can be studied by setting up a con-

trolled experiment.

d.Controlled experiments cannot be performedon living things.

6. What are the goals of science?

7. How does an observation about an object differfrom an inference about that object?

8. How does a hypothesis help scientists understandthe natural world?

9. Why does it make sense for scientists to test just onevariable at a time in an experiment?

10. Distinguish between an experimental group and acontrol group.

11. What steps are involved in drawing aconclusion?

12. How can a graph of data be more informativethan a table of the same data?

Think Critically

13.Design an Experiment Suggest an experimentthat would show whether one food is better thananother at speeding an animals growth.

14.Control Variables Explain why you cannot drawa conclusion about the effect of one variable in an

investigation when the other key variables are notcontrolled.

1 21.2 Science in Context


15. A skeptical attitude in science a.prevents scientists from accepting new ideas. b. encourages scientists to readily accept new ideas. c.means a new idea will only be accepted if it is

backed by evidence. d.is unimportant.

16. The purpose of peer review in science is toensure that

a.all scientific research is funded. b. the results of experiments are correct. c. all scientific results are published. d. published results meet standards set by the

scientific community.

17. A scientific theory is

a.the same as a hypothesis. b. a well-tested explanation that unifies a broad

range of observations. c.the same as the conclusion of an experiment. d. the first step in a controlled experiment.

18. Why are scientific theories useful?

19. Why arent theories considered absolute truths?

Assessment1

28 Chapter 1 Assessment


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Think Critically

20. Evaluate Why is it misleading to describe scienceas a collection of facts?

21.Propose a Solution How would having a scien-tific attitude help you in everyday activities, forexample, in trying to learn a new skill?

22.Conduct Peer Review If you were one of theanonymous reviewers of a paper submitted

for publication, what criteria would you use todetermine whether or not the paper should bepublished?

1 31.3 Studying Life


23.The process in which two cells from differentparents unite to produce the first cell of a neworganism is called

a.homeostasis.

b. development.c. asexual reproduction.d. sexual reproduction.

24.The process by which organisms keep their inter-nal conditions relatively stable is called

a.metabolism.b. a genome.c. evolution.d. homeostasis.

25. How are unicellular and multicellular organisms

alike? How are they different?26. Give an example of changes that take place as cells

in a multicellular organism differentiate.

27. List three examples of stimuli that a birdresponds to.

Think Critically

28. Measure Use a ruler to find the precise lengthand width of this book in millimeters.

29. Interpret Visuals Each of the following safetysymbols might appear in a laboratory activity in

this book. Describe what each symbol stands for.(Hint:Refer to Appendix B.)

1 2 3 4

HEIGHT BY PRESCRIPTIONAlthough scientific studies have notproved that HGH treatment sig-

nificantly increases adult height,they do suggest that extra HGHmay help some short kids grow tallersooner. Parents who learn about this possibilitymay want treatment for their children. Davidsdoctor prescribed HGH to avoid criticism for nopresenting it as an option. This situation is new. Many years ago, HGHwas available only from cadavers, and it was prescribed only for people with severe medical problems. Then, genetic engineering made it possible

to mass-produce safe, artificial HGH for medicausesafe medicine for sick people. However, many people who are shorter thanaverage often face prejudice in our society. Thisled drug companies to begin marketing HGHto parents of healthy, short kids. The message:Help your child grow taller!

As Davids case illustrates, science has thepowerful potential to change lives, but new sci-entific knowledge and advances may raise morquestions than they answer. Just because sciencmakes somethingpossible, does that mean its

rightto do it? This question is difficult to answWhen considering how science should be appliewe must consider both its limitations and itscontext in society.

1.Relate Cause and Effect Search the Inter-net for the latest data on HGH treatment ofhealthy children. What effect does early HGtreatment have on adult height?

2.Predict HGH was among the first productsof the biotechnology revolution. Many morare in the pipeline. As products become avaable that could change other inherited traitswhat challenges await society?

3.Connect to the Why wouldit be important for scientists to communi-cate clearly the results of HGH studies? Howmight parents benefit by understanding thescience behind the results?

Chapter 1 Untamed Science Video Chapter Mystery


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Connecting Concepts

Use Science GraphicsThe following graphs show the size of four different

populations over a period of time. Use the graphs to

answer questions 3032.

30.Analyze Data Write a sentence summarizingwhat each graph shows.

31. Interpret Graphs Before any of the graphs couldbe used to make direct comparisons among thepopulations, what additional information wouldbe necessary?

32.Compare and Contrast Graphs of completelydifferent events can have the same appearance.Select one of the graphs and explain how theshape of the graph could apply to a different setof events.

Write About Science

33. Explanation Suppose you have a pet cat and wantto determine which type of cat food it prefers.Write an explanation of how you could use scien-tific methodology to determine the answer. (Hint:Before you start writing, list the steps you mighttake, and then arrange them in order beginningwith the first step.)

34.Assess the Many people add

fertilizer to their house and garden plants. Makea hypothesis about whether you think fertilizersreally help plants grow. Next, design an experi-ment to test your hypothesis. Include in your planwhat variable you will test and what variables youwill control.

Changes in Four Populations

TimeNumberofOrganisms 1

NumberofOrganisms 2

Time

TimeNumberofOrganisms

NumberofOrganisms

Time

3 4

35. Interpret Graphs The independent variable inthe controlled experiment was the

a.number of flies. b. number of groups studied. c. number of days. d. size of the containers.

36. Infer Which of the following is a logical infer-ence based on the content of the graph?

a.The flies in Group B were healthier than those

in Group A. b.A fly population with more available space

will grow larger than a population with lessspace.

c.If Group B was observed for 40 more days, thesize of the population would double.

d.In 40 more days, the size of both populationswould decrease at the same rate.

A researcher studied two groups of fruit flies:

Population A was kept in a 0.5 L container;

Population B was kept in a 1 L container.

Time (days)

Number

ofFlies

Fruit Fly Population

900

800

700

600

500

400

300

200

100

04 12 20 280 8 16 24 32 36 40

B

A

30 Chapter 1 Assessment


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Standardized Test PrepMultiple Choice

1. To ensure that a scientific work is free of bias andmeets standards set by the scientific community, aresearch groups work is peer reviewed byA anonymous scientific experts.

B the general public.C the researchers friends.D lawmakers.

2. Which of the following characteristics is NOTshared by both a horse and the grass it eats?A uses energyB response to stimulusC movement from place to placeD stable internal environment

3. Which of the following statements about a scientific

theory is NOT true?A It has the same meaning in science as it does in

daily life.B It enables scientists to make accurate predic-

tions about new situations.C Scientific theories tie many hypotheses together.D It is based on a large body of evidence.

4. A bird-watcher sees an unusual bird at a feeder. Hetakes careful notes on the birds color, shape, andother physical features and then goes to a refer-ence book to see if he can identify the species. What

aspect of scientific thinking is most apparent in thissituation?A observationB inferenceC hypothesis formationD controlled experimentation

5. Unlike sexual reproduction, asexual reproductioninvolvesA two cells. C one parent.B two parents. D one nonliving thing.

6. One meter is equal toA 1000 millimeters.B 1 millimeter.C 10 kilometers.D 1 milliliter.

Questions 78

Once a month, a pet owner recorded the mass of hepuppy in a table. When the puppy was 3 months olshe started to feed it a special puppy food she sawadvertised on TV.

7. According to the table, which statement is trueA The puppys mass increased at the same rate

each month shown.B The puppys mass was less than 5 kg at the s

of the new diet.C The puppy gained 5 kg between age 3 and

4 months.D The puppy had gained 13 kg as a result of th

new diet.

8. All of the following statements about the pet owstudy are true EXCEPTA The owner used the metric system.B The owner recorded data.C The owner could graph the data.D The owner conducted a controlled experim

Open-Ended Response

9. Explain how a controlled experiment works.

If You Have Trouble With . . .Question 1 2 3 4 5 6 7 8 9

Age(months)

Mass at Startof Month (kg)

2

3

4

5

813

Change in a Puppys Mass Over Time

Change in Massper Month (kg)

35

1. chapter 1 student edition full

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