Chapter 1 The Science of Biology Summary...Chapter 1 The Science of Biology 1–1 What Is Science? ... Evolution: This is the main unifying theme of biology because this theory tells

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Chapter 1 The Science of Biology

1–1 What Is Science?Science is an organized way of using evidence to learn about the natural world. Scientific thinking usually begins withobservation, which is the process of gather-ing information about events or processesin a careful, orderly way. The informationgathered from observations is called data.Quantitative data are expressed as num-bers, obtained by counting or measuring.Qualitative data are descriptive and involvecharacteristics that can’t usually be counted.Scientists use data to make inferences. Aninference is a logical interpretation based onprior knowledge or experience.

After making first observations, aresearcher will propose one or morehypotheses. A hypothesis is a proposed scientific explanation for a set of observa-tions. Scientists generate hypotheses usingprior knowledge, logical inference, andinformed, creative imagination. Scientifichypotheses must be proposed in a way thatenables them to be tested. Hypotheses aretested by performing controlled experi-ments. The conclusions researchers drawfrom experiments or data must be valid. Tobe valid, a conclusion must be based on logi-cal interpretation of reliable data.

1–2 How Scientists WorkConducting a scientific investigation involvesa series of steps. The first step is asking aquestion. The second step involves forming ahypothesis. The third step in conducting ascientific investigation is setting up a con-trolled experiment. A hypothesis should betested by an experiment in which only onevariable is changed at a time. All other vari-ables should be kept unchanged. This type ofexperiment is called a controlled experiment.The variable that is deliberately changed iscalled the manipulated variable. The variablethat is observed and that changes in response

to the manipulated variable is called theresponding variable.

The fourth step in conducting a scien-tific investigation is recording and analyzingresults. The fifth step is drawing a conclu-sion. A key assumption in science is thatexperimental results can be reproduced.

As evidence builds up, a particularhypothesis may become so well supportedthat scientists consider it a theory. In science,a theory is a well-tested explanation thatunifies a broad range of observations.

1–3 Studying LifeAlthough living things vary greatly, all liv-ing things share eight characteristics:

1. Living things are made up of units calledcells. Cells are the smallest units of anorganism that can be considered alive.

2. Living things reproduce. In sexual repro-duction, cells from two different parentsunite to produce the first cell of the neworganism. In asexual reproduction, a single cell divides in half to form twonew organisms.

3. Living things are based on a universalgenetic code. The directions for inheri-tance are carried by a molecule calledDNA.

4. Living things grow and develop. Multi-cellular organisms typically go through aprocess called development. As cellsdivide, they change in shape and struc-ture in a process called differentiation.

5. Living things obtain and use materialsand energy. The combination of chemicalreactions through which an organismbuilds up or breaks down materials as itcarries out its life processes is calledmetabolism.

Summary

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6. Living things respond to their environ-ment. A stimulus is a signal to which anorganism responds.

7. Living things maintain a stable internalenvironment. The process by which theydo this is called homeostasis.

8. Taken as a group, living things changeover time. Change over time in livingthings is called evolution.

All biological sciences are tied togetherby overriding themes, or “big ideas.” Youwill see that these big ideas overlap andconnect with one another. The 10 big ideasin biology are as follows:

1. Evolution: This is the main unifyingtheme of biology because this theorytells us that all forms of life on Earth arerelated to a common ancestor andtherefore explains the unity and diver-sity of life.

2. Science as a Way of Knowing: Science isnot a list of facts, but a method of studythat explains the natural world in termsof forces and events.

3. Matter and Energy: Life’s most basicrequirements are matter, which servesas nutrients, and energy, which fuelsthe processes of life.

4. Interdependence in Nature: Within thebiosphere, organisms are linked to oneanother and to the land, water, and airaround them.

5. Cellular Basis of Life: A cell is the small-est unit capable of all life functions. Thebasic structure of the cell is the same inall organisms.

6. Information and Heredity: Life’s pro-cesses are directed by information car-ried in a genetic code.

7. Unity and Diversity of Life: All organ-isms are composed of a common set ofcarbon-based molecules, use proteins,and store a common genetic code.

8. Structure and Function: Each majorgroup of organisms has its own bodyparts to serve specific functions.

9. Homeostasis: All organisms must main-tain a stable internal environment inorder to function properly.

10. Science, Technology, and Society: Peo-ple must truly understand what scienceis and how it works in order to makeeducated decisions about our worldand how our activities impact it.

Biology is divided into different fields ofstudy. Some fields focus on the study of liv-ing systems at different levels. These levelsinclude, from smallest to largest: molecules,cells, groups of cells, organisms, popula-tions, communities, ecosystems, and thebiosphere.

1–4 Tools and ProceduresMost scientists use the metric system whencollecting data. The metric system is a deci-mal system of measurement whose units arebased on certain physical standards and arescaled on multiples of 10.

A microscope is a device that producesmagnified images of structures that are toosmall to see with the unaided eye. Lightmicroscopes produce magnified images byfocusing visible light rays. Compound lightmicroscopes allow light to pass through thespecimen and use two lenses to form animage. Electron microscopes use beams ofelectrons to produce magnified images.Biologists use two main types: the transmis-sion electron microscope (TEM) and thescanning electron microscope (SEM).

Whenever you work in your biologylaboratory, it’s important for you to followsafe practices. The single most importantrule for your safety is simple: Always fol-low your teacher’s instructions and the text-book directions exactly. Because you may bein contact with organisms you cannot see, itis essential that you wash your hands thor-oughly after every scientific activity.


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Section 1–1 What Is Science? (pages 3–7)

Key Concept• What is the goal of science?

What Science Is and Is Not (page 3)

1. What is the goal of science?

2. What is science?

Thinking Like a Scientist (page 4)

3. What is observation?

4. The information gathered from observation is called .

5. Complete the table about the types of data.

Type Data Involves . . . Example

Numbers

Characteristics that cannot be easily measured or counted

TYPES OF DATA

6. What is an inference?


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Explaining and Interpreting Evidence (page 5)

7. What is a hypothesis?

8. In science, a hypothesis is useful only if it can be .

9. Is the following sentence true or false? A hypothesis should be stated in such a way

that it can never be proved wrong.

10. What are three sources from which hypotheses may arise?

a.

b.

c.

11. Circle the letter of each of the following that may be an outcome of testing a hypothesis.

a. The hypothesis is partly true but needs to be revised.

b. The hypothesis is wrong.

c. The hypothesis is supported.

d. The hypothesis is of no value.

Science as a Way of Knowing (page 6)

12. What do scientists assume about the universe?

13. What are some qualities that are desirable in a scientist?

Science and Human Values (page 7)

14. Is the following sentence true or false? A community must use its shared values to

make decisions about scientific issues.


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Section 1–2 How Scientists Work (pages 8–14)

Key Concepts• How do scientists test hypotheses?

• How does a scientific theory develop?

Designing an Experiment (pages 8–10)

1. The idea that life can arise from nonliving matter is called

.

2. What was Francesco Redi’s hypothesis about the appearance of maggots?

3. What are variables in an experiment?

4. Ideally, how many variables should an experiment test at a time?

5. What is a controlled experiment?

6. The illustration below shows the beginning of Redi’s experiment. Complete the illustration by showing the outcome.

Covered jars

Redi’s Experiment on Spontaneous Generation

Uncovered jars

Severaldays pass.


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7. Complete the table about variables.

Type of Variable Definition

Manipulated variable

Responding variable

VARIABLES

8. In Redi’s experiment, what were the manipulated variable and the responding variable?

9. For what do scientists use the data from a controlled experiment?

10. When scientists look for explanations for specific observations, what do they assume

about nature?

Repeating Investigations (pages 10–12)

11. Why do scientists assume that experimental results can be reproduced?

12. What did Anton van Leeuwenhoek discover?

13. What did John Needham conclude from his test of Redi’s findings?

14. What did Spallanzani do to improve upon Redi’s and Needham’s work?

15. How did Pasteur settle the spontaneous generation argument?


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When Experiments Are Not Possible (page 13)

16. In animal field studies, why do scientists usually try to work without making the

animals aware that humans are present?

17. When a controlled experiment is not possible, why do scientists try to identify as many

relevant variables as possible?

How a Theory Develops (pages 13–14)

18. In science, what is a theory?

19. Is the following sentence true or false? A theory may be revised or replaced by a more

useful explanation.

Reading Skill PracticeA flowchart can help you remember the order in which a set of events has occurredor should occur. On a separate sheet of paper, create a flowchart that represents theprocess that Redi carried out in his investigation of spontaneous generation. Thisprocess is explained under the heading Designing an Experiment on pages 8–10. Formore information about flowcharts, see Organizing Information in Appendix A ofyour textbook.


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Section 1–3 Studying Life (pages 15–22)

Key Concepts• What are some characteristics of living things?

• How can life be studied at different levels?

Introduction (page 15)

1. What is biology?

Characteristics of Living Things (pages 15–17)

2. What is a cell?

3. Circle the letter of each sentence that is true about cells.

a. A cell is the smallest unit of an organism that can be consideredalive.

b. A multicellular organism may contain trillions of cells.

c. A living thing that consists of a single cell is a multicellularorganism.

d. Organisms are made up of cells.

4. What are two types of reproduction?

a.

b.

5. Living things are based on a universal .6. Circle the letter of each sentence that is true about living things.

a. The life cycle of many organisms involves development.b. For bacteria, growth is mostly a simple increase in size.c. Each type of organism has a distinctive life cycle.d. Cells may change in number but never differentiate.

7. Why does an organism need energy and a constant supply of materials?

8. Is the following sentence true or false? All organisms respond to the environment in

exactly the same ways.


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Big Ideas in Biology (pages 18–20)

9. What is homeostasis?

10. A group of organisms that changes over time is said to .

Branches of Biology (pages 20–21)

Match the different kinds of biologists with the focus of their study.Kinds of Biologists11. Zoologist

12. Botanist

13. Paleontologist

14. Label each of the illustrations below according to the level of study represented.

Focus of Studya. Plantsb. Ancient lifec. Animals

15. The largest level of biological study is the .

Biology in Everyday Life (page 22)

16. What kinds of information can the study of biology provide about matters affecting

human society?


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Section 1–4 Tools and Procedures (pages 24–28)

Key Concepts• What measurement system do most scientists use?

• How are light microscopes and electron microscopes similar? How are they different?

A Common Measurement System (page 24)

1. Why do scientists need a common system of measurement?

2. When collecting data and doing experiments, what system of measurement do most

scientists use?

3. What is the metric system?

4. Complete each equation by writing the correct number or metric unit.

a. 1000 meters = 1

b. 1 liter = milliliters

c. 1 gram = milligrams

d. 1000 kilograms = 1

Analyzing Biological Data (page 25)

5. When scientists collect data, what are they often trying to find out?

6. What does a graph of data make easier to recognize and understand than a table of

data?

Microscopes (pages 25–26)

7. What are microscopes?

8. What are compound light microscopes?

9. How do chemical stains make light microscopes more useful?


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10. What are the two main types of electron microscopes?

a.

b.

11. Compare how a TEM and an SEM produce images.

12. How must samples be prepared for observation by an electron microscope?

Laboratory Techniques (page 27)

13. A group of cells grown in a nutrient solution from a single original cell is called a(an) .

14. What technique do biologists use to separate one part of a cell from the rest of the cell?

Working Safely in Biology (page 28)

15. What is the single most important rule for your safety while working in a laboratory?


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Vocabulary ReviewCompletion Fill in the blanks with terms from Chapter 1.

1. The process of gathering information about events or processes in a careful, orderly

way is called .

2. The information gathered from observations is called .

3. A(An) is a logical interpretation based on prior knowledge

or experience.

4. A(An) is a proposed scientific explanation for a set of

observations.

5. In a(an) experiment, only one variable is changed at a time,

while all other variables are kept unchanged.

6. The variable that is deliberately changed in a controlled experiment is called the

variable.

7. A(An) is a well-tested explanation that unifies a broad range

of observations.

8. In reproduction, the new organism has a single parent.

9. A(An) is a signal to which an organism responds.

10. The system is a decimal system of measurement whose units

are based on certain physical standards and are scaled on multiples of 10.

Matching In the space provided, write the letter of the definition that best matches each term.

_____ 11. biology

_____ 12. microscope

_____ 13. cell

_____ 14. cell fractionation

_____ 15. homeostasis

_____ 16. metabolism

_____ 17. cell culture

a. a collection of living matter enclosed by a barrier thatseparates it from its environment

b. combination of chemical reactions through which anorganism builds up or breaks down materials

c. a laboratory technique in which a group of cells developsfrom a single cell

d. process of keeping an organism’s internal conditionsconstant

e. a device that produces magnified images of structuresthat are too small to see with the unaided eye

f. a laboratory technique in which cells are separated intocell parts

g. the science that seeks to understand the living world


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Chapter 1 The Science of Biology Summary...Chapter 1 The Science of Biology 1–1 What Is Science? ... Evolution: This is the main unifying theme of biology because this theory tells