B C B C B Hippocrates What is biology? - CARSON'S BIOLOGY...
Transcript of B C B C B Hippocrates What is biology? - CARSON'S BIOLOGY...
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
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The following standards are covered in Unit 1:Investigation and Experimentations: 1k, 1f, 1g
California Standards
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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
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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.
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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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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
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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.
A
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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.
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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.
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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 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
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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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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.
B
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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
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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
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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?
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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.
KS Studios
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
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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.
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KS Studios
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.
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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.
GG
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Cork cells as drawnby Robert Hooke
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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
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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
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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
Num
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f par
amec
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urvi
ving
Temperature
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
09 10 11 12
20
40
60
80
100
Grade
Perc
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MaleFemale
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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
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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
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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.
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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?
Pill bug length in mm
1
2
3
4
5
Total
Average time
Organization and Growth and Development
Data Table
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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
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Num
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Pill Bug Length: Classroom Data
Length in millimeters1
100908070605040302010
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Num
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Pill Bug Length: Internet Data
Response time in minutes2
100908070605040302010
4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
Num
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Average Pill Bug Response Time: Internet Data
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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.
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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
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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.
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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.
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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.
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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.
Seed
s g
erm
inat
ed
Day
10
0
20
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50
1 2 3 4 5 6 7 8 9 10
The Effect of Temperature on Germination
Experimental group
Control groupx x
x
x
x xx x x x
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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.
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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.
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1f
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