section 1.3 1 - miss cooke's science...

Objectives• Identify the different elements of

scientific inquiry.• Differentiate between theories and

hypotheses.

Section ResourcesUnit Resource Book

Study Guide pp. 9–10Power Notes p. 11Reinforcement p. 12

Interactive Reader Chapter 1Spanish Study Guide pp. 5–6

Biology Toolkit pp. C7, C10

TechnologyPower Presentation 1.3Media Gallery DVDOnline Quiz 1.3

Activate Prior Knowledge Quiz students on the nature of a hypothesis. Ask, Is this a hypothesis: “If I keep a plant from getting any sunlight, it will die.” No, it’s a prediction. Discuss the difference between a prediction and a hypothesis. Remind students that a hypothesis is worded in such a way as to show a relationship that can be tested. Ask, How can you reframe the predic-tion about the plant to make it a hypothesis? “If sunlight is necessary to the survival of a plant, then when a plant is deprived of sunlight, it will die.” Point out that a hypothesis implies a question to be answered.

VocabularyAcademic Vocabulary Point out that a scientist typically describes a hypothesis in terms of validity, rather than truth. Validity implies a proposition or an argument is well grounded or logically derived. Truth is, more simply, the quality of being real, genuine, or factual.

Plan and PreparePlan and Prepare

TeachTeach

FIGURE 1.8 Biology, like other areas of science, depends on observations.

1.3 Scientific Thinking and ProcessesKEY CONCEPT Science is a way of thinking, questioning, and gathering evidence.

MAIN IDEAS• Like all science, biology is a process

of inquiry.• Biologists use experiments to test

hypotheses.• A theory explains a wide range of

observations.

VOCABULARYobservation,observation, p. 13

data,data, p. 14

hypothesis,hypothesis, p. 14

experiment,experiment, p. 16

independent variable,independent variable, p. 16

dependent variable,dependent variable, p. 16

constant,constant, p. 16

theory,theory, p. 16

Connect What does the study of fungus have in common with the study of human heart disease? How is research in a laboratory similar to research in a rain forest? Biologists, like all scientists, ask questions about the world and try to find answers through observation and experimentation. How do your daily observations help answer questions that you have about the world?

MAIN IDEA

Like all science, biology is a process of inquiry.Science is a human process of trying to understand the world around us. There is no one method used by all scientists, but all scientific inquiry is based on the same principles. Scientific thinking is based on both curiosity and skepticism. Skepticism is the use of critical and logical thinking to evaluate results and conclusions. Scientific inquiry also requires evidence. One of the most impor-tant points of science is that scientific evidence may support or even overturn long-standing ideas. To improve our understanding of the world, scientists share their findings with each other. The open and honest exchange of data is extremely important in science.

Observations, Data, and HypothesesAll scientific inquiry begins with careful and systematic observations. Of course, observation observation includes using our senses to study the world, but it may also involve other tools. For example, scientists use computers to collect measurements or to examine past research results. Much early biological research was based on observing, de-scribing, and categorizing the living world. By them-selves, description and categorization are not as common in research today due to advances in technology, but they are still very important in biology. For example, how could someone study the interactions of gorillas without observing and describing their behavior, as in FIGURE 1.8?

Chapter 1: Biology in the 21st Century 13

b10hspe-010103.indd 13 9/2/08 12:13:20 P

Differentiated Instruction

SECTION 1.3

ENGLISH LEARNERSRemind students that people ask questions to get information. Provide practice with clarification techniques by using phrases such as the following:

I didn’t understand what you said.Could you repeat that, please?Does ___ mean ___?

Also, have students ask questions related to what they have read or you have explained. Review the question words What, Who, When, Where, Why, and How.

Model this technique for students by asking some questions about the nature of scientific thinking, such as the following:

What makes a scientist a scientist?How do scientists approach their work?Why do scientists do experiments?

Ask students to form their own questions about Section 1.3 to ask one another in groups. Tell students that you consider their questions a sign of critical thinking, and emphasize that the questions are an excellent tool for making meaning clear.


b10hste-0101.indd 13b10hste-0101.indd 13 9/10/08 10:13:46 AM9/10/08 10:13:46 AM

History of ScienceThe scientific tradition began in ancient Greece and is generally attributed to Aristotle. He was the first individual we know of to explain biological phenom-ena in terms of natural causes, as opposed to supernatural or mythical causes. He used the power of logic to find explanations for cause and effect, and form and function. Aristotle’s most powerful tools consisted of his powers of observation and reasoning. Aristotle and the natural philosophers who followed him established a set of widely held assumptions about the natural world and how it functioned. Typically, answers to specific questions had to fit within this framework of assumptions, which provided a predeter-mined explanation. One such assump-tion was that the Sun and all the other stars and planets revolved around Earth.With the Scientific Revolution of the 17th century, a new methodology came into being. This new scientific method started with data and observations, from which an explanation was derived, and incorporated experimentation to test assumptions. In 1620, Francis Bacon outlined the approach in his work Novum Organum, which carried the subtitle True Suggestions for the Interpretation of Nature. In 1637, René Descartes framed the principles of scientific thinking in his Discourse on Method. Descartes described reconstructing the accepted body of knowledge, piece by piece, trusting only that which could be seen to be beyond any doubt.

VocabularyAcademic Vocabulary The term significant commonly means “impor-tant,” but in statistics, significant means “not likely due to chance.” Explain that a finding may be statistically significant without being important in the real world. When statisticians say that a result is statistically significant, they mean that a change in a dependent variable is probably due to manipulation of the independent variable. That probability is typically 95 percent.

Teach continuedTeach continued

l C d 2 03240 Fil N bh 010103 i dd U hl b L M difi d 6/23/06 1 57 PM

FIGURE 1.9 In this experiment, a scientist studies how chemicals are detected in the mouth and nose to produce taste.

ConnectingData Analysis Biology relies on the analysis of scientific data. Use the Data Analysis activities in each chapter in this book to build your data analysis skills.

CONCEPTS Scientific questions often come from observations, whether the observa-tions are one’s own or someone else’s. Observations can also be recorded asdata data that can be analyzed. Scientists collect two general types of data: qualita-tive data and quantitative data. As you learned on page 12, qualitative data aredescriptions of a phenomenon that can include sights, sounds, and smells.This type of data is often useful to report what happens but not how it hap-pens. In contrast, quantitative data are characteristics that can be measured orcounted, such as mass, volume, and temperature. Anything that is expressed asa number, from time to a rating scale on a survey, is quantitative data that canbe used to explore how something happens.

Scientists use observations and data to form a hypothesis. A hypothesishypothesis(plural, hypotheses) is a proposed answer for a scientific question. A hypothesismust be specific and testable. You probably form and test many hypothesesevery day, even though you may not be aware of it. Suppose you oversleep. Youneeded to get up at 7 A.M., but when you wake up you observe that it is8 A.M. What happened? Did the alarm not go off? Was it set for the wrongtime? Did it go off but you slept through it? You just made three hypothesesto explain why you overslept—the alarm did not go off, the alarm was set forthe wrong time, or the alarm went off but you did not hear it.

Testing HypothesesA hypothesis leads to testable predictions of what would happen if the hypoth-esis is valid. How could you use scientific thinking to test a hypothesis about

oversleeping? If you slept late because the alarm was set for thewrong time, you could check the alarm to find out the time forwhich it was set. Suppose the alarm was actually set for 7 P.M. Inthis case, your hypothesis would be supported by your data, andyou could be certain that the alarm was set for the wrong time.

For scientists, just one test of a hypothesis is usually notenough. Most of the time, it is only by repeating tests that scien-tists can be more certain that their results are not mistaken or dueto chance. Why? Biological systems are highly variable. By repeat-ing tests, scientists take this variability into account and try todecrease its effects on the experimental results.

After scientists collect data, they use statistics to mathemati-cally analyze whether a hypothesis is supported. There are twopossible outcomes of statistical analysis.

• Nonsignificant The data show no effect, or an effect so smallthat the results could have happened by chance.

• Statistically significant The data show an effect that is likelynot due to chance.

When data do not support a hypothesis, it is rejected. But these data arestill useful because they often lead to new hypotheses.

Experimental methods and results are evaluated by other scientists ina process called peer review. How was an experiment done and how werethe data analyzed? Do the data support the conclusions of the experiment?

14 Unit 1: Introducing Biology

hspe-010103.indd Sec3:14 6/23/06 2:10:27 PM


BELOW LEVELTell students that there are different strate-gies for previewing a section. Introduce students to the PLAN strategy: Predict, Locate, Add, and Note. Have students predict what the section will be about by reading the headings and locating key vocabulary. They should write down their predictions and any questions they have. As they read, they can add details and note how the material addresses their questions.

Biology Toolkit, PLAN, p. C714 Unit 1: Introducing Biology

Take It FurtherTell students that a hypothesis cannot be proved, only tested. Applying logic, if something cannot be proved, then it cannot be disproved. Data either support or do not support a hypothesis, and the hypothesis is accepted or rejected—not proved.Part of establishing support for a hypothesis is to subject experimental results and data to peer review. It is rare for one researcher to spot every mistake or flaw in a complicated investigation. Errors and opportunities for improve-ment may stand out only to another scientist with special expertise, increas-ing the probability that weaknesses in an experiment will be identified and fixed.

AnswersA Synthesize during “testing hypoth-

eses” (to repeat the experiment) and after “analyzing data” (if the hypothesis is rejected) or “evaluating results” (if other data agree or disagree)B Synthesize The steps can occur in

different orders and depend on what is being investigated.

FIGURE 1.10 Scientific ThinkingScience is a cycle. The steps are shown in a certain order, but the cycle does not begin or end at any one point, and the steps may take place in various orders.

Synthesize Where in the cycle would retesting a hypothesis fit? Explain.

Observing Scientists make observations and examine prior research.

Testing hypotheses Scientists collect data that they use to support or reject a hypothesis.

Forming hypotheses Scientists ask questions and try to explain observations.

Analyzing data Scientists analyze their data to draw conclusions about their research.

Evaluating results Scientists eval-uate the data and conclusions presented by other scientists.

Is there bias in the experimental design or in the conclusions? Only after thisreview process is complete are research results accepted. Whether the resultssupport an existing theory or disagree with earlier research, they are oftenused as a starting point for new questions. In FIGURE 1.10, you see the cycle ofobserving, forming hypotheses, testing hypotheses, analyzing data, andevaluating results that keeps scientific inquiry going.

Synthesize Why is there no one correct process of scientific investigation?

MAIN IDEA

Biologists use experiments to test hypotheses.You have read about the importance of observations in science. Observationalstudies help biologists describe and explain something in the world. But inobservational studies, scientists try not to interfere with what happens. Theytry to simply observe a phenomenon. One example involves the endangeredwhite stork. The number of white storks has decreased sharply over the last 50years. To help protect the storks, biologists have studied the migration pat-terns of the birds. What can observational studies tell a biologist about storkpopulations and migration? The studies can show changes in migration pathand distance. They can show where storks breed and how many eggs they lay.Observational studies can answer all of these questions. But there is onequestion that observations cannot answer: What causes any changes that mightbe observed? The only way to answer that question is through an experiment.


bhspe-010103.indd Sec3:15 6/23/06 2:10:30 INCLUSIONA science class offers a variety of students important information that will help them function in an increasingly technological society. Below is a list of ways to accommo-date all students in a comfortable learning environment:• Provide a daily, unvarying routine so your

expectations are clear.• Establish special teaching procedures that

take into account a short attention span and restlessness.

• Make certain that students understand instructions before they start work.

• Seat students where classroom distractions are minimized.

• Be selective about which concepts students should master.

• Encourage repeated efforts.• Within reasonable expectations, evaluate

students’ grasp of concepts, not spelling, punctuation, or sentence structure.

A

B


VocabularyAcademic Vocabulary Point out that in everyday use, an observation may be “a comment based on something seen.” In this use, an interpretation, or inference, has been made. In science, an observa-tion must be detectable with the senses or a measurement tool. Show students an apple and then have them identify the following statements as observa-tions or inferences. 1. The skin is red. observation 2. The apple is edible. inference 3. There are seeds inside. inference 4. It can make you healthy. inference 5. It feels smooth. observation

Take It FurtherResearchers involved in experiments that test human reactions often apply an added system of control to their investigations. This is because a test subject’s expectations can affect the results. For example, in a clinical trial for a new drug, just the knowledge that a person is receiving an active drug may produce some benefit or cause a doctor to look for improvement. In such an instance, investigators use a randomized, double-blind, placebo-controlled study. This ensures that psychological factors do not affect the results.The study employs two drugs, the active one that researchers expect to be an effective treatment and a placebo, a substance that has no treatment value but outwardly appears identical to the active drug. The study is made random by using a computer to randomly determine who receives the drug and who receives the placebo. The proce-dure is double blind because neither the participating doctors nor their test subjects know which drug (active or placebo) the subject is receiving.

AnswersA Infer A change in the independent

variable is potentially the cause of a measured effect in the dependent variable.

Teach continuedTeach continued

Ul C d 2 03240 Fil N bh 010103 i dd U L M difi d 1/5/07 12 02 PM

VISUAL VOCAB

The independent variable independent variable is a condition that is manipulated, or changed, by a scientist.

Dependent variablesDependent variables are observed and measured during an experiment; they are the experimental data.

independent variable

dependent variable

affects

VOCABULARYIn common usage, the term constant means “unchanging.” In experimental research, a constant is a condition or fac-tor that is controlled so that it does not change.

Scientific experiments allow scientists to test hypotheses and find out howsomething happens. In experiments,experiments, scientists study factors called indepen-dent variables and dependent variables to find cause-and-effect relationships.The independent variableindependent variable in anexperiment is a condition that ismanipulated, or changed, by a scien-tist. The effects of manipulating anindependent variable are measured bychanges in dependent variables.Dependent variables Dependent variables are observedand measured during an experiment;they are the experimental data.Changes in dependent variables“depend upon” the manipulation ofthe independent variable. Suppose ascientist is testing medications to treat high blood pressure. The independentvariable is the dose of medication. The dependent variable is blood pressure.

Ideally, only one independent variable should be tested in an experiment.Thus, all of the other conditions have to stay the same. The conditions that donot change during an experiment are called constants.constants. To study the effects ofan independent variable, a scientist uses a control group or control condition.Subjects in a control group are treated exactly like experimental subjectsexcept for the independent variable being studied. The independent variable ismanipulated in experimental groups or experimental conditions.

Constants in the blood pressure medication experiment include how oftenthe medication is given, and how the medication is taken. To control theexperiment, these factors must remain the same, or be held constant. Forexample, the medication could be tested with 0, 25, 50, or 100 milligramdoses, twice a day, taken by swallowing a pill. By changing only one variable ata time—the amount of medication—a scientist can be more confident thatthe results are due to that variable.

Infer How do experiments show cause-and-effect relationships?

MAIN IDEA

A theory explains a wide range of observations.Many words have several different meanings. Depending on the context inwhich a word is used, its meaning can change completely. For example, theword right could mean “correct,” or it could refer to a direction. Similarly, theword theory has different meanings. Usually, the word theory in everydayconversation means a speculation, or something that is imagined to be true.In science, the meaning of theory is very different.

Recall that a hypothesis is a proposed answer for a scientific question. Atheorytheory is a proposed explanation for a wide range of observations andexperimental results that is supported by a wide range of evidence. Eventually,a theory may be broadly accepted by the scientific community. Natural


hspe-010103.indd 16 1/5/07 12:03:11


TEACH WITH TECHNOLOGYTo hone students’ powers of observation, find a videoclip that shows an interesting and complex event. It might be a magic trick or a visually arresting advertisement. Play the clip, then ask students to write down all that they saw. Play the clip again, asking them to observe the event more carefully. Then have students share what they saw, comparing their first perception of the event to their second.

PRE-APWorking in small groups, have students consider how a theory provides a framework for the way scientific investigations are conducted. They should identify a theory that served for a time and then was supplanted by another, for example, the geocentric and helio-centric theories; spontaneous generation and the cell theory. Students should compile what they know about the theories, the effect a wrong theory has, and a theory’s predictive value. Then discuss the results in class.

Biology Toolkit, Round Table, p. C10

A


00.2 ASSESSMENT

B

A

B

Chapter 00: Chapter Name 17

Address MisconceptionsCommon Misconception Students may think that all questions can be answered by using scientific methods.Correcting the Misconception Explain that scientific methods apply only to the study of phenomena that can be observed and measured. Appreciation of beauty and personal tastes, for example, are outside of the realm of scientific investigation.

AnswersA Summarize a well-accepted

explanation for a wide range of observations and experimental results, supported by a body of evidence

Assess Use the Online Quiz or Section Quiz (Assessment Book, p. 7).Reteach Work with students to incorporate the key vocabulary of the section into either a cluster diagram or concept map. You can print out a description of each graphic organizer, and a blank, from the Biology Toolkit.

Assess and ReteachAssess and Reteach

1.3 ASSESSMENT

Connecting CONCEPTS

ONLINE QUIZClassZone.com

FIGURE 1.11 For many years, scientific evidence indicated that stomach ulcers (top) were caused by stress. Then, new evidence showed that the ulcers are actu-ally caused by a type of bacteria called Helicobacter pylori (bot-tom). (colored SEM; magnification 4000!)

bacteria stomachlining

To learn more about scientific methods, go to scilinks.org.Keycode: MLB001

selection is a scientific theory. It is supported by a large amount of data, and it explains many observations of life on Earth. Theories are not easily accepted in science, and by definition they are never proved. Scientific hypotheses and theories may be supported or refuted, and they are always subject to change. New theories that better explain observations and experimental results can replace older theories.

Theories can change based on new evidence. One example of how scientific understanding can change involves the cause of disease. Until the mid 1800s, illnesses were thought to be related to supernatural causes or to imbalances of the body’s “humours,” or fluids. Then scientific research suggested that diseases were caused by microscopic organisms, such as bacteria. The germ theory of disease was born, but it has changed over the years. For example, an early addition to the germ theory stated that it must be possible to grow a disease-causing microorganism in a laboratory.

Now, we know that viruses and prions do not completely fit the germ theory of disease because they are not living organisms. A virus has some of the characteristics of life, but it cannot reproduce itself without infecting a living cell. Prions are even less like organisms—they are just misfolded pro-teins. The link between prions and disease was not even suggested until the early 1980s, but much evidence points to prions as the cause of mad cow disease and, in humans, Creutzfeldt–Jakob disease.

The details of germ theory have changed as our knowledge of biology has grown, but the basic theory is still accepted. Scientists must always be willing to revise theories and conclusions as new evidence about the living world is gathered. Science is an ongoing process. New experiments and observations refine and expand scientific knowledge, as you can see in FIGURE 1.11. Our understanding of the world around us has changed dramatically over the past few decades, and the study of biology has changed and expanded as well.

Summarize What is a scientific theory?

REVIEWING MAIN IDEAS

1. What role do hypotheseshypotheses play in scientific inquiry?

2. What is the difference between an independent variableindependent variable and a dependent variabledependent variable?

3. How is the meaning of theorytheory in science different from the everyday use of the term?

CRITICAL THINKING

4. Compare and Contrast How are hypotheses and theories related?

5. Apply Give examples of different ways in which observationsobservations are used in scientific inquiry.

6. Scientific Process Why is the statement “All life is made of cells” an example of a theory? Explain.


10hspe-010103.indd 17b10hspe-010103.indd 17 8/12/08 4:42:18 PM8/12/08 4:42:18

1.3 ASSESSMENT 1. A hypothesis provides a testable explana-

tion for an observation. 2. An independent variable is manipulated, a

dependent variable shows the effect of that manipulation.

3. A scientific theory is a widely accepted explanation that is supported by evidence. In everyday language, a theory is a guess.

4. Hypotheses and theories are both proposed explanations for a scientific question. Observations and data collected in testing hypotheses contribute to the

broader question that is addressed by a theory. A theory, in turn, provides the framework for new hypotheses.

5. Scientific questions are developed from initial observations. Observations are also made to test hypotheses.

6. When first proposed, the idea that all life is made of cells changed the way scientists thought about what defines an organism. Not only did it encompass all accumulated evidence, but it also provided a framework for new investigations.

A


b10hste-0101.indd 17b10hste-0101.indd 17 9/9/08 3:04:28 PM9/9/08 3:04:28 PM

section 1.3 1 - miss cooke's science...

Documents