Chapter 1: The Study of Life PDF

Biology/Life Sciences 1.c, 1.f, 5.c, 6.a, 6.f, 6.g, 9.g; I&E 1.a, 1.b, 1.c, 1.d, 1.f, 1.g, 1.j, 1.k, 1.l The Study of Life Section 1 Introduction to Biology -!). )DEA All living things share the characteristics of life. Section 2 The Nature of Science -!). )DEA Science is a process Earth based on inquiry that seeks to develop explanations. Section 3 Methods of Science -!). )DEA Biologists use specific methods when conducting research. Human population BioFacts There are approximately 200 billion stars that make up the Milky Way galaxy. Humans are 1 out of an estimated 100 million species of life on Earth. The human brain is made up of 100 billion neurons. Human neurons Color-Enhanced SEM Magnification: unavailable 2 (t)Photo Library International/Photo Researchers, (c)CORBIS, (b)SPL/Photo Researchers, (bkgd)Myron Jay Dorf/CORBIS Start-Up Activities I&E 1.d LAUNCH Lab Biologists Make the following Foldable to help you organize examples of things biologists do. Why is observation important in science? STEP 1 Stack three sheets of notebook Scientists use a planned, organized approach to paper 2.5 cm apart as illustrated. solving problems. A key element of this approach is gathering information through detailed observations. Scientists extend their ability to observe by using scientific tools and techniques. Procedure 1. Read and complete the lab safety form. 2. Pick an unshelled peanut from the container of peanuts. Carefully observe the peanut using your senses and available tools. Record your observations. STEP 2 Bring up the bottom edges and fold to form five tabs of equal size. 3. Do not change or mark the peanut. Return your peanut to the container. 4. After the peanuts are mixed, locate your peanut based on your recorded observations. Analysis 1. List the observations that were the most helpful in identifying your peanut. Which were the least helpful? STEP 3 Rotate your Foldable 180°. 2. Classify your observations into groups. Staple along the folded edge to secure all 3. Justify why it was important to record sheets. Label the tabs Some Roles of detailed observations in this lab. Infer why Biologists, Study the diversity of life, observations are important in biology. Research diseases, Develop technology, Improve agriculture, and Preserve the environment. -iÊ,iÃÊvÊ }ÃÌÃ Visit biologygmh.com to: ▶ study the entire chapter online -ÌÕ`ÞÊÌ iÊ`ÛiÀÃÌÞÊvÊvi ,iÃi>ÀV Ê`Ãi>ÃiÃ ▶ explore the Interactive Time Line, iÛi«ÊÌiV }Þ «ÀÛiÊ>}ÀVÕÌÕÀi Concepts in Motion, Interactive Tables, *ÀiÃiÀÛiÊÌ iÊiÛÀiÌ Microscopy Links, Virtual Labs, and links to virtual dissections ▶ access Web links for more information, &/,$!",%3 Use this Foldable with projects, and activities Section 1.1. As you study the section, summar- ▶ review content online with Interactive ize these examples of the different roles of Tutor and take Self-Check Quizzes biologists. Section 1Chapter XXXXXXXXXXXXXXXXXX 1 The Study of Life 3 Biology/Life Sciences 6.a Students know biodiversity is the sum total of different kinds of organisms and is affected by alterations of habitats. Also covers: Biology/Life Sciences 1.c, 1.f, 5.c, 6.f, 6.g, 9.g Section 1.1 Objectives ◗ Define biology. Introduction to Biology ◗ Identify possible benefits from studying biology. -!). )DEA All living things share the characteristics of life. ◗ Summarize the characteristics of living things. Real-World Reading Link Think about several different living or once-living things. The bacteria that live in your small intestine, the great white sharks in the Review Vocabulary ocean, a field of corn, a skateboarder, and the extinct Tyrannosaurus rex differ in environment: the living and nonliving structure and function. Who discovered what all these things have in common? things that surround an organism and with which the organism interacts The Science of Life New Vocabulary Before Jane Goodall, pictured in Figure 1.1, arrived in Gombe Stream biology National Park in Tanzania in 1960 to study chimpanzees, the world of organism chimpanzees was a mystery. Jane’s curiosity, determination, and organization patience over a long period of time resulted in the chimpanzee troop’s growth acceptance of her presence so that she was able to observe their behav- development reproduction ior closely. species When people study living things or pose questions about how living stimulus things interact with the environment, they are learning about biology— response the science of life. Life flourishes on Earth, and a curiosity about life is a homeostasis major reason why some people study biology. adaptation In biology, you will study the origins and history of life and once-living things, the structures of living things, how living things interact with one another, and how living things function. This will help you understand how humans have a vital role in preserving the natural environment and sustaining life on Earth. Have you ever hiked in a forest and wondered why different trees have leaves with different shapes? Maybe you have watched an ant quickly cross the sidewalk toward a breadcrumb and wondered how the ant knew that the breadcrumb was there. When you ask these ques- tions, you are observing, and you are asking questions about life. VOCABULARY WORD ORIGIN Biology bio– prefix; from the Greek word bios, meaning life. –logy suffix; from the Greek word logos, meaning study. Figure 1.1 Jane Goodall conducted field research for many years to observe chimpanzee behavior. Predict the types of questions you would ask if you observed chimpanzee behavior. 4 Chapter 1 The Study of Life Karl Ammann/CORBIS What do biologists do? Imagine being the first person to look into a microscope and discover cells. What do you think it was like to find the first dinosaur fossils that indicated feathers? Who studies how organisms, including the marbled stargazer fish in Figure 1.2, obtain food? Will the AIDS virus be defeated? Is there life on other planets or anywhere else in the uni- verse? The people who study biology—biologists—make discoveries and seek explanations by performing laboratory and field investigations. Throughout this textbook, you will discover what biologists in the real world do and you will learn about careers in biology. Study the diversity of life Jane Goodall, shown in Figure 1.1, studied chimpanzees in their natural environ- ments. She asked questions such as, “How do chimpanzees behave in the wild?” and “How can chimpanzee behaviors be characterized?” From her recorded and detailed obser- Figure 1.2 The marbled stargazer fish lives beneath the vations, sketches, and maps of chimpanzees’ daily travels, ocean floor off the coast of Indonesia. It explodes upward from Goodall learned how chimpanzees grow and develop and beneath the sand to grab its food. how they gather food. She studied and recorded chimpan- Observe How does this fish hide from its food? zee reproductive habits and their aggressive nature. She learned that they use tools. Goodall’s data provided a better understanding of chimpanzees, and as a result, scientists &/,$!",%3 know how to best protect them. Incorporate information from this section into your Foldable. Research diseases Mary-Claire King also studied chimpanzees—not their behavior but their genetics. In 1973, she established that the genomes (genes) of chim- Figure 1.3 A prosthetic “bionic” hand is new technology panzees and humans are 99 percent identical. Her work that can help extend human capabilities. currently focuses on unraveling the genetic basis of breast cancer, a disease that affects one out of eight women. Many biologists research diseases. Questions such as “What causes the disease?”, “How does the body fight the disease?”, and “How does the disease spread?” often guide biologists’ research. Biologists have developed vaccines for smallpox, chicken pox, and diphtheria, and currently, some biologists are researching the development of a vac- cine for HIV. Other biologists focus their research on diseases such as diabetes, avian flu, anorexia, and alcohol- ism, or on trauma such as spinal cord injuries that result in paralysis. Biologists worldwide are researching new medicines for such things as lowering cholesterol levels, fighting obesity, reducing the risk of heart attacks, and preventing Alzheimer’s disease. Develop technologies When you hear the word technology, you might think of high-speed computers, cell phones, and DVD players. However, technology is defined as the application of scientific knowledge to solve human needs and to extend human capabilities. Figure 1.3 shows how new technology—a “bionic” hand—can help some- one who has lost an arm. Section 1 Introduction to Biology 5 (t)Reinhard Dirscherl/Visuals Unlimited, (b)Mike Derer/AP/Wide World Photos For example, Charles Drew was a doctor who pioneered meth- ods to separate blood plasma from blood cells and safely store and transport blood plasma for transfusions. His research led to blood banks that saved soldiers during World War II and helps countless patients today. Biologists today continue to discover new ways to improve and save lives. For example, the field of bioengineering applies knowledge gained from studying the function of living systems to the design of mechanical devices such as artificial limbs. In addition, biologists in the field of biotechnology research cells, DNA, and living systems to discover new medicines and medical treatments. Improve agriculture Some biologists study the possibilities of genetically engineering plants to grow in poor soils or to resist insects, fungal infections, or frost damage. Other biologists research agricultural issues to improve food production to feed the world’s growing human population. Figure 1.4 Joanne Chory, a plant biologist, Joanne Chory, a plant biologist shown in Figure 1.4, studies researches how plants respond to light. mustard plants’ sensitivity to light and their responses when exposed to different light sources, different times of exposure, and other conditions. Because of her work with plant growth hormones and light, agriculturists might be able to increase the amount of food produced from crops or to grow crops in areas where they normally would not grow. Preserve the environment Environmental biologists seek to prevent the extinction of animals and plants by developing ways to protect them. Some biologists study the reproductive strategies of endangered species while they are in captivity. Other biologists work in nature preserves that provide safe places for endangered species to live, reproduce, and have protection against poachers. Lee Anne Martinez is an ecologist who worked to protect the environment where outdoor toilets are common. She helped people in rural Africa construct composting toilets that use no water. The Figure 1.5 Streptococcus pyogenes is a unicellular organism. It can infect the throat, composted waste from the toilets can be added to soil to improve it sinuses, or middle ear. for agricultural use. The Characteristics of Life Have you ever tried to define the word alive? If you were to watch a grizzly bear catch a salmon from a river, you obviously would conclude that the bear and salmon are both alive. Is fire alive? Fire moves, increases in size, has energy, and seems to reproduce, but how does fire differ from the bear and salmon? Over time and after many observations, biologists concluded that all living things have certain characteristics, as listed in Table 1.1. An organism is anything that has or once had all these characteristics. Made of one or more cells Have you ever had strep throat? It probably was caused by a group A streptococcal bacte- ria, such as the Streptococcus pyogenes shown in Figure 1.5. A bacterium is unicellular—it has just one cell—yet it displays all the characteristics of life just like a skin cell on your body or a cell in a plant’s leaf. Humans and plants are multicellular—they have many cells. SEM Magnification: 7300⫻ 6 Chapter 1 The Study of Life (t)Salk Institute for Biological Studies, (b)Dr. Fred Hossler/Visuals Unlimited Interactive Table To explore more Table 1.1 Characteristics of Living Organisms about the characteristics of life, visit biologygmh.com. Characteristic of Life Example Description Magnification: 160⫻ All organisms are made of one or more cells. The cell is the basic unit of life. Some Made of one or organisms, such as the Paramecium sp., more cells are unicellular. The levels of organization in biological systems begin with atoms and molecules and increase in complexity. Each organized structure in an organ- Displays organization ism has a specific function. The structure of an anteater’s snout relates to one of its functions— a container for the anteater’s long tongue. Growth results in an increase in mass. Development results in different abilities. A bullfrog tadpole grows and develops into an Grows and develops adult bullfrog. Organisms reproduce and pass along traits from one generation to the next. For a species like the koala to continue to exist, reproduction Reproduces must occur. Reactions to internal and external stimuli are called responses. This cheetah responds to the need for food by chasing a gazelle. The gazelle Responds to stimuli responds by running away. Energy is required for all life processes. Many organisms, like this squirrel, must take in food. Other organisms make their own food. Requires energy All organisms keep internal conditions stable by a process called homeostasis. For example, Maintains humans perspire to prevent their body homeostasis temperature from rising too high. Adaptations are inherited changes that occur over time that help the species survive. Adaptations evolve Tropical orchids have roots that are adapted over time to life in a soil-less environment. Section 1 Introduction to Biology 7 (t to b)M.I. Walker/Photo Researchers, (2)Tom J. Ulrich/Visuals Unlimited. (3 4)Gary Meszaros/Visuals Unlimited, (5)Tom McHugh/Photo Researchers, (6)W. Wisniewski/zefa/CORBIS, (7)OSF/G.I. Bernard/ Animals Animals, (8)Ron Fehling/Masterfile, (9)Stephen J. Krasemann/Photo Researchers (l)Alan & Sandy Carey/Peter Arnold, Inc., (c)Richard Nowitz/National Geographic Society Image Collection, (r)Joe McDonald/CORBIS Figure 1.6 In less than a month, these robin chicks grow and develop from helpless Cells are the basic units of structure and function in all living things. chicks to birds capable of flying. For example, each heart cell has a structure that enables it to contribute Infer how the robins have developed in to the heart’s function—continually pumping blood throughout the other ways. body. Likewise, each cell in a tree’s roots has a structure that enables it to help anchor the tree in the ground and to take in water and dissolved minerals from the surrounding soil. Displays organization Think of all the people in your high school building each day. Students, faculty, counselors, administrators, build- ing service personnel, and food service personnel are organized based on the different tasks they perform and the characteristics they share. For example, the students are designated freshmen, sophomores, juniors, and seniors based on age and coursework. Living things also display organization, which means they are arranged in an orderly way. The Paramecium in Table 1.1 is made up of one cell, yet that cell is a collection of organized structures that carries on life functions. Each of those structures is composed of atoms and mole- cules. The many cells that make up the robin chicks in Figure 1.6 also contain structures made of atoms and molecules. However, in multicellular organisms, specialized cells are organized into groups that work together called tissues. These tissues are organized into organs, which carry on functions such as digestion and reproduction. Organ systems work together to support an organism. You will learn in Chapter 3 how individ- ual organisms are organized and supported by the biosphere. I&E 1.d, 1.g Observe Characteristics of Life Is it living or nonliving? In this lab, you will observe several objects to determine if they are living or nonliving. Procedure 1. Read and complete the lab safety form. 2. Create a data table with four columns titled Object, Prediction, Characteristic of Life, and Evidence. 3. Your teacher will provide several objects for observation. List each object in your table. Predict whether each object is living or nonliving. 4. Carefully observe each object. Discuss with your lab partner what characteristics of life it might exhibit. 5. Use Table 1.1 to determine whether each object is living or nonliving. List the evidence in your data table. Analysis 1. Compare and contrast your predictions and observations. 2. Explain why it was difficult to classify some objects as living or nonliving. 8 Chapter 1 The Study of Life Grows and develops Most organisms begin as one cell. Growth results in the addition of mass to an organism and, in many organisms, the formation of new cells and new structures. Even a bacterium grows. Think about how you have grown throughout your life. Robin chicks, like those in Figure 1.6, cannot fly for the first few weeks of their lives. Like most organisms, robins develop struc- tures that give them specific abilities, such as flying. Development is the process of natural changes that take place during the life of an organism. Reproduces Most living things are the result of reproduction—the Careers In biology production of offspring. Reproduction is not an essential characteristic for individual organisms. Many pets are spayed or neutered to prevent Biology Teacher An enthusiasm for unwanted births. Obviously, these pets can still live even though they biology is one of the many reasons cannot reproduce. However, if a species is to continue to exist, then people become biology teachers. Other members of that species must reproduce. A species is a group of organ- than courses in biological sciences, isms that can breed with one another and produce fertile offspring. If the prospective biology teachers might individuals of a species do not reproduce, then when the last individual take classroom management, teaching of that species dies, the species becomes extinct. methods, and other courses needed to develop teaching skills. For more Responds to stimuli An organism’s external environment information on biology careers, visit includes all things that surround it, such as air, water, soil, rocks, and biologygmh.com. other organisms. An organism’s internal environment is all things inside it. Anything that is part of either environment and causes some sort of reaction by the organism is called a stimulus (plural, stimuli). The reaction to a stimulus is a response. For example, if a shark smells blood in the ocean, it will respond quickly by moving toward the blood and attacking any organism present. Plants also respond to their envi- ronments, but they do so more slowly than most other organisms. If you have a houseplant and you place it near a sunny window, it will grow toward the window in response to the light. How does the Venus flytrap in Figure 1.7 respond to stimuli? Figure 1.7 In nature, this Venus flytrap Being able to respond to the environment is critical for an organism’s grows in soils that lack certain nutrients. The safety and survival. If an organism is unable to respond to danger or to plant captures and digests insects and takes in needed nutrients. react to potential enemies, it might not live long enough to reproduce. Explain How does this plant respond to stimuli to obtain food? Section 1 Introduction to Biology 9 (l)Hal Horwitz/CORBIS, (r)David M. Dennis/Animals Animals Gerry Ellis/Minden Pictures Requires energy Living things need sources of energy to fuel their life functions. Living things get their energy from food. Most plants and some unicellular organisms use light energy from the Sun to make their own food and fuel their activities. Other unicellular organisms can transform the energy in chemical compounds to make their food. Organisms that cannot make their own food, such as animals and fungi, get energy by consuming other organisms. Some of the energy that an organism takes in is used for growth, development, and main- taining homeostasis. However, most of the energy is transformed into thermal energy and is radiated to the environment as heat. Maintains homeostasis Regulation of an organism’s internal con- ditions to maintain life is called homeostasis (hoh mee oh STAY sus). Homeostasis occurs in all living things. If anything happens within or to an organism that affects its normal state, processes to restore the normal state begin. If homeostasis is not restored, death might occur. Figure 1.8 The structure of a drip-tip leaf #ONNECTION TO %ARTH 3CIENCEWhen athletes travel to a location that is is an adaptation to rainy environments. at a higher altitude than where they live, they generally arrive long before the competition so that their bodies have time to adjust to the thinner air. At higher altitudes, air has fewer molecules of gases, including oxy- gen, per unit of volume. Therefore, there is less oxygen available for an athlete’s red blood cells to deliver to the cells and tissues, which disrupts his or her body’s homeostasis. To restore homeostasis, the athlete’s body produces more red blood cells. Having more red blood cells results in an adequate amount of oxygen delivered to the athlete’s cells. R Adaptations evolve over time Many trees in rain forests have leaves with drip tips, like the one shown in Figure 1.8. Water runs off more easily and quickly from leaves with drip tips. Harmful molds and mildews will not grow on dry leaves. This means a plant with dry leaves is healthier and has a better chance to survive. Drip tips are an adapta- tion to the rain forest environment. An adaptation is any inherited char- acteristic that results from changes to a species over time. Adaptations like rain forest trees with drip tips enable species to survive and, there- fore, they are better able to pass their genes to their offspring. Biology/Life Sciences 1.c, 1.f, 5.c, Section 1.1 Assessment 6.a, 6.f, 6.g Section Summary Understand Main Ideas Think Scientifically ◗ Biology is the science of life. 1. -!). )DEA Describe four char- acteristics used to identify whether ◗ Biologists study the structure and func- 5. something is alive. -!4( IN "IOLOGY Survey tion of living things, their history, their students in your school—biology stu- interactions with the environment, and 2. Explain why cells are considered dents and non-biology students—and many other aspects of life. the basic units of living things. adults. Have participants choose char- ◗ All organisms have one or more cells, 3. List some of the benefits of study- acteristics of life from a list of various display organization, grow and develop, ing biology. characteristics and rank their choices reproduce, respond to stimuli, use 4. Differentiate between response from most important to least impor- energy, maintain homeostasis, and and adaptation. tant. Record, tabulate, average, and have adaptations that evolve over time. graph your results. Prepare a report that summarizes your findings. 10 Chapter 1 The Study of Life Self-Check Quiz biologygmh.com I&E 1.k Recognize the cumulative nature of scientific evidence. Also covers: I&E 1.c, 1.d, 1.f, 1g, 1.l Section 1. 2 Objectives ◗ Explain the characteristics of The Nature of Science science. ◗ Compare something that is -!). )DEA Science is a process based on inquiry that seeks to scientific with something that is develop explanations. pseudoscientific. ◗ Describe the importance of the Real-World Reading Link If you see a headline that reads “Alien baby found metric system and SI. in campsite,” how do you know whether you should believe it or not? How do you know when to trust claims made in an advertisement on television or the Review Vocabulary Internet, or in a newspaper or magazine? What makes something science-based? investigation: a careful search or examination to uncover facts What is science? New Vocabulary Have you ever wondered how science is different from art, music, and science writing? Science is a body of knowledge based on the study of nature. theory Biology is a science, as are chemistry, physics, and Earth science, which peer review you might also study during high school. The nature, or essential char- metric system SI acteristic, of science is scientific inquiry—the development of explana- forensics tions. Scientific inquiry is both a creative process and a process rooted ethics in unbiased observations and experimentation. Sometimes scientists go to extreme places to observe and experiment, as shown in Figure 1.9. Relies on evidence Has anyone ever said to you, “I have a theory about that?” That person probably meant that he or she had a possible explanation about something. Scientific explanations combine what is already known with consistent evidence gathered from many observations and experiments. When enough evidence from many related investigations supports an idea, scientists consider that idea a theory—an explanation of a nat- ural phenomenon supported by many observations and experiments over time. For example, what happens when you throw a ball up in the air anywhere on Earth? The results are always the same. Scientists explain how the ball is attracted to Earth in the theory of universal gravitation. In biology, two of the most highly regarded theories are the cell theory and the theory of evolution. Both theories are based on countless observations and investigations, have extensive supporting evidence, and enable biologists to make accurate predictions. Figure 1.9 This volcanologist is near molten lava flowing from Mount Etna. Lava temperatures can reach 750°C. Section 2 The Nature of Science 11 (l)Jeremy Bishop/SPL/Photo Researchers, (r)J.G. Paren/SPL/Photo Researchers #ONNECTION TO (ISTORY In the eighteenth and nineteenth centuries, many people practiced physiognomy (fih zee AHG nuh mee)—judging someone’s character or personality based on physical features, espe- cially facial features. Phrenology (frih NAH luh jee), the practice of reading the bumps on a person’s head, illustrated in Figure 1.10, also is a type of physiognomy. Physiognomy often was used to determine whether individuals were appropriate for employment and other roles in society, or whether they had criminal tendencies. In fact, Charles Darwin almost did not get to take his famous voyage on the HMS Beagle because of the shape of his nose. Physiognomy was used and accepted even though there was no scientific evidence to support it. Although physiognomy was based on observations and what was known at the time, it was not supported by scientific explanation. Physi- ognomy is considered a pseudoscience (soo doh SI uhnts). Pseudo- sciences are those areas of study that try to imitate science, often driven by cultural or commercial goals. Astrology, horoscopes, psychic reading, Figure 1.10 Phrenology is based on tarot card reading, face reading, and palmistry are pseudosciences. They observation—not scientific evidence. do not provide science-based explanations about the natural world. Reading Check Describe one way that science and pseudoscience differ. Expands scientific knowledge How can you know what informa- tion is science-based? Most scientific fields are guided by research that results in a constant reevaluation of what is known. This reevaluation often leads to new knowledge that scientists then evaluate. The search for new knowledge is the driving force that moves science forward. Nearly every new finding, like the discoveries shown in Figure 1.11, causes scien- tists to ask more questions that require additional research. With pseudoscience, little research is done. If research is done, then often it is simply to justify existing knowledge rather than to extend the knowledge base. Pseudoscientific ideas generally do not ask new ques- tions or welcome more research. Figure 1.11 Milestones in Biology ▼ Major events and discoveries in the past 1953 The structure of century greatly contributed to our DNA is identified due to understanding of biology today. research by Rosalind Franklin, Maurice Wilkins, James Watson, and Francis Crick. Chapter 12 1962 Rachel Carson’s book Silent ▼ 1912–1939 Writings on cell Spring, about the environmental dan- biology by Ernest Everett Just gers of pollution and pesticide use, is influence the use of scientific published. Chapter 2 methods in biology. Chapter 7 12 Chapter 1 The Study of Life (t)Mary Evans Picture Library/The Image Works, (c)Dr. Tim Evans/Photo Researchers, (b)SPL/Photo Researchers Thumb Finger Thumb Bird Bat Human Two fingers Four fingers Four fingers Figure 1.12 The structure of a bat’s wing is more like that of a human arm than Challenges accepted theories Scientists welcome debate about a bird’s wing. one another’s ideas. They regularly attend conferences and meetings where they discuss new developments and findings. Often, disagree- ments occur among scientists. Then additional investigations and/or experiments are done to substantiate claims. Sciences advance by accommodating new information as it is dis- covered. For example, since the emergence of AIDS in the 1980s, our understanding of HIV, our ideas about how HIV is transmitted, the manner in which we treat AIDS, and the ways in which we educate people about the disease have changed dramatically due to new infor- Careers In biology mation from many scientific studies. Questions results Observations or data that are not consistent with Science Writer Communicating current scientific understanding are of interest to scientists. These incon- scientific information to the public is sistencies often lead to further investigations. For example, early biolo- one of the goals of a science writer. gists grouped bats with birds because both had wings. Further study He or she might write news stories, showed that bat wings are more similar to mammalian limbs than they manuals, or press releases, or edit and summarize the written materials are to bird wings, as shown in Figure 1.12. This led to an examination of of scientists. For more information the anatomy, genes, and proteins of rats and bats. The relationship was on biology careers, visit confirmed, and scientists established that bats were more closely related biologygmh.com. to mammals than birds. With pseudoscience, observations or data that are not consistent with beliefs are discarded or ignored. 1978 Mary Leakey ▼ discovers three sets of fossilized foot- 2003 An international prints about 3.5 effort to sequence 2005 Functioning brain million years old in human DNA—the cells are grown from stem Laetoli, Tanzania. Human Genome Project cells that have been Chapter 16 —is completed. removed from the brains of Chapter 13 adult mice. Chapter 9 ▼ 1997 A worldwide study of Y chromosomes adds evidence Interactive Time Line to the theory that modern To learn more about these discoveries and humans emerged from Africa others, visit biologygmh.com. approximately 200,000 years ago. Chapter 16 Section 2 The Nature of Science 13 (t)John Reader/SPL/Photo Researchers, (b)Andrew Syred/Photo Researchers VOCABULARY Tests claims Whenever biologists engage in research, they use stan- ACADEMIC VOCABULARY dard experimental procedures. Science-based information makes Unbiased: claims based on a large amount of data and observations obtained from To be objective, impartial, or fair. unbiased investigations and carefully controlled experimentation. Con- The judges were unbiased in choosing clusions are reached from the evidence. However, pseudoscientists the winner. often make claims that cannot be tested. These claims often are mix- tures of fact and opinion. Undergoes peer review Before it is made public, science-based information is reviewed by scientists’ peers—scientists who are work- ing in the same field of study. Peer review is a process by which, in science, the procedures used during an experiment and the results are evaluated by other scientists who are in the same field or who are conducting similar research. Uses metric system Scientists can repeat the work of others as part of a new experiment. Using the same system of measurements helps make this possible. Most scientists use the metric system when collecting data and performing experiments. The metric system uses units with divisions that are powers of ten. The General Conference of Weights and Measures established the unit standards of the metric sys- tem in 1960. The system is called the International System of Units, commonly known as SI. In biology, the SI units you will use most often are meter (to measure length), gram (to measure mass), liter (to mea- sure volume), and second (to measure time). Data Analysis lab 1.1 I&E 1.a, 1.c, 1.d, 1.l Based on Real Data* Peer Review Can temperature be predicted by counting cricket chirps? Many outdoors enthusiasts Effect of Temperature on Chirping claim that air temperature (°F) can be estimated Temperature (°F) Cricket Chirps (per min) by adding the number 40 to the number of cricket chirps counted in 15 seconds. Is there 68 121 scientific evidence to support this idea? 75 140 Data and Observations A group of students collected the data at right. 80 160 They concluded that the claim is correct. 81 166 Think Critically 1. Convert the number of chirps per minute to 84 181 the number of chirps per 15 seconds. 88 189 2. Plot the number of chirps per 15-second interval versus Fahrenheit temperature. Draw 91 200 the best-fit line on your graph. Refer to the Skillbuilder Handbook, pages 1115–1118, for 94 227 help with graphs. 3. Write the equation for the best-fit line. 4. Peer review Do the results support the stu- *Data obtained from: Horak, V. M. 2005. Biology as a source for algebra equations: dents’ conclusion? Explain. insects. Mathematics Teacher 99(1): 55-59. 14 Chapter 1 The Study of Life Science in Everyday Life There is widespread fascination with science. Popular television pro- grams about crime are based on forensics, which is the field of study that applies science to matters of legal interest. The media is filled with information on flu epidemics, the latest medical advances, discoveries of new species, and technologies that improve or extend human lives. Clearly, science is not limited to the laboratory. The results of research go far beyond reports in scientific journals and meetings. Science literacy In order to evaluate the vast amount of information available in print, online, and on television, and to participate in the fast- paced world of the twenty-first century, each of us must be scientifically literate. A person who is scientifically literate combines a basic under- standing of science and its processes with reasoning and thinking skills. Many of the issues that are faced every day relate to the world of biol- Figure 1.13 DNA analysis might exclude ogy. Drugs, alcohol, tobacco, AIDS, mental illness, cancer, heart disease, an alleged thief because his or her DNA does and eating disorders provide subjects for biological research worldwide. not match the DNA from the crime scene. Environmental issues such as global warming, pollution, deforestation, the use of fossil fuels, nuclear power, genetically modified foods, and conserv- ing biodiversity are issues that you and future generations will face. Also, genetic engineering, cloning—producing genetically identical individuals, genetic screening—searching for genetic disorders in people, euthanasia (yoo thuh NAY zhuh)—permitting a death for reasons of mercy, and cry- onics (kri AH niks)—freezing a dead person or animal with the hope of reviving it in the future—all involve ethics, which is a set of moral princi- ples or values. Ethical issues must be addressed by society based on the val- ues it holds important. Scientists provide information about the continued expansion of science and technology. As a scientifically literate adult, you will be an educated consumer who can participate in discussions about impor- tant issues and support policies that reflect your views. Who knows? You might serve on a jury where DNA evidence, like that shown in Figure 1.13, is presented. You will need to understand the evidence, comprehend its implications, and decide the outcome of the trial. I&E 1.c, 1.d, 1.f, 1.g, 1.k, 1.l Section 1.2 Assessment Section Summary Understand Main Ideas Think Scientifically ◗ Science is the study of nature and 1. -!). )DEA Describe the is rooted in observation and characteristics of science. 5. "IOLOGY Predict experimentation. 2. Define scientific theory. what might happen to a population ◗ Pseudoscience is not based on standard of people who do not understand the 3. Defend the use of the metric scientific research; it does not deal with nature of science. Use examples of system to a scientist who does testable questions, welcome critical key issues facing our society. not want to use it. review, or change its ideas when new discoveries are made. 4. Compare and contrast science 6. -!4( IN "IOLOGY One kilo- with pseudoscience. gram equals 1000 grams. One milli- ◗ Science and ethics affect issues in gram equals 0.001 grams. How many health, medicine, the environment, milligrams are in one kilogram? and technology. Self-Check Quiz biologygmh.com Section 2 The Nature of Science 15 David Parker/SPL/Photo Researchers I&E 1.k Recognize the cumulative nature of scientific evidence. Also covers: I&E 1.a, 1.b, 1.c, 1.d, 1.f, 1.g, 1.j Section 1. 3 Objectives ◗ Describe the difference between Methods of Science an observation and an inference. ◗ Differentiate among control, -!). )DEA Biologists use specific methods when conducting independent variable, and dependent research. variable. ◗ Identify the scientific methods a Real-World Reading Link What do you do to find answers to questions? Do biologist uses for research. you ask other people, read, investigate, or observe? Are your methods haphazard or methodical? Over time, scientists have established standard procedures to find Review Vocabulary answers to questions. theory: an explanation of a natural phenomenon supported by many observations and experiments over time Ask a Question Imagine that you saw an unfamiliar bird in your neighborhood. New Vocabulary You might develop a plan to observe the bird for a period of time. observation Scientific inquiry begins with observation, a direct method of inference gathering information in an orderly way. Often, observation involves scientific method hypothesis recording information. In the example of your newly discovered serendipity bird, you might take photographs or draw a picture of it. You might experiment write detailed notes about its behavior, including when and what it ate. control group Science inquiry involves asking questions and processing informa- experimental group tion from a variety of reliable sources. After observing the bird, you independent variable might combine what you know with what you have learned and begin dependent variable a process of making logical conclusions. This process is called making constant inferences, or inferring. For instance, if you saw a photo of a bird simi- data lar to the unfamiliar bird in your neighborhood, you might infer that safety symbol your bird and the bird in the photo are related. Figure 1.14 illustrates how a field guide might be helpful in making inferences. Scientific methods Biologists work in different places to answer their questions. For example, some biologists work in laboratories, per- haps developing new medicines, while others work outdoors in natural settings. No matter where they work, biologists all use similar methods to gather information and to answer questions. These methods some- times are referred to as scientific methods, illustrated in Figure 1.15. Figure 1.14 Scientists might use a field Even though scientists do not use scientific methods in the same way guide to help them identify or draw conclusions each time they conduct an experiment, they observe and infer through- about things they observe in nature, such as this out the entire process. peregrine falcon. 16 Chapter 1 The Study of Life (l)Frans Lanting/Minden Pictures Visualizing Scientific Methods Figure 1.15 I&E 1.a, 1.b, 1.c, 1.d, 1.f, 1.g, 1.j, 1.k The way that scientists answer questions is through an organized series of events called scientific methods. There are no wrong answers to questions, only answers that provide scientists with more information about those questions. Questions and collected information help scientists form hypotheses. As experiments are conducted, hypotheses might or might not be supported. /BSERVE AN UNEXPLAINED PHENOMENON #OLLECT INFORMATION -AKE OBSERVATIONS !SK QUESTIONS 5SE PRIOR KNOWLEDGE 2EVIEW RELATED RESEARCH &ORM A HYPOTHESIS $ESIGN AN EXPERIMENT TO TEST THE CHOSEN HYPOTHESIS #ONDUCT AN EXPERIMENT AND RECORD THE DATA #OMPARE ACTUAL RESULTS EXPECTED RESULTS 2EPEAT EXPERIMENT MANY TIMES UNTIL RESULTS 2EFINE AND TEST AN ARE CONSISTENT $RAW A CONCLUSION ALTERNATE HYPOTHESIS (YPOTHESIS IS SUPPORTED (YPOTHESIS IS NOT SUPPORTED 2EPORT RESULTS OF THE EXPERIMENT #OMPARE RESULTS FROM SIMILAR EXPERIMENTS ,EADS TO ADDITIONAL ACCEPTED HYPOTHESIS EXPERIMENTATION BASED ON ACCEPTED HYPOTHESIS Interactive Figure To see an animation of scientific methods, visit biologygmh.com. Section 3 Methods of Science 17 Form a Hypothesis Imagination, curiosity, creativity, and logic are key elements of the way biologists approach their research. In 1969, the U.S. Air Force asked Dr. Ron Wiley to investigate how to enhance a pilot’s ability to endure the effects of an increase in gravity (g-force) while traveling at high speed in an F-16 aircraft. It was known that isometrics, which is a form of exercise in which muscles are held in a contracted position, raised blood pressure. Wiley formed the hypothesis that the use of isometric exercise to raise blood pressure during maneuvers might increase toler- ance to g-force and prevent blackouts. A hypothesis (hi PAH thuh sus) Study Tip is a testable explanation of a situation. Before Wiley formed his hypothesis, he made inferences based on Clarification Choose a concept his experience as a physiologist, what he read, discussions with Air Force from the text and write its definition in personnel, and previous investigations. He did find that increasing a the middle of a piece of paper. Circle pilot’s blood pressure could help the pilot withstand g-forces. But he also the most important word. Around the word, write ideas related to it or made an unexpected discovery. examples that support it. During his study, Dr. Wiley discovered that isometric exercise decreased the resting blood pressure of the pilots. As a result, weight lift- ing and muscle-strengthening exercises are recommended today to help people lower blood pressure. Serendipity is the occurrence of accidental or unexpected but fortunate results. There are other examples of seren- dipity throughout science. For example, the discovery of penicillin was partially due to serendipity. When a hypothesis is supported by data from additional investiga- tions, usually it is considered valid and is accepted by the scientific community. If not, the hypothesis is revised, and additional investi- gations are conducted. Collect the Data LAUNCH Lab Imagine that while in Alaska on vacation, you noticed various kinds of Review Based on what you’ve read about observing and inferring, how gulls. You saw them nesting high in the cliffs, and you wondered how would you now answer the analysis they maintain their energy levels during their breeding season. A group questions? of biologists wondered the same thing and did a controlled experiment using gulls known as black-legged kittiwakes shown in Figure 1.16. When a biologist conducts an experiment, he or she investigates a phe- nomenon in a controlled setting to test a hypothesis. Figure 1.16 This colony of black-legged kittiwakes along the Alaskan coast includes nesting pairs. 18 Chapter 1 The Study of Life George McCarthy/CORBIS I&E 1.a, 1.b, 1.c, 1.d, 1.f, 1.g, 1.j, 1.k Controlled experiments The biologists inferred that the kittiwakes would have more energy if they were given extra feedings while nesting. The biologists’ hypothesis was that the kittiwakes would use the extra energy to lay more eggs and raise more chicks. Biologists found nesting pairs of kittiwakes in Alaska that were similar in mass, age, size, and all other Manipulate Variables features. They set up a control group and an experimen- How does a biologist establish experimental tal group. A control group in an experiment is a group conditions? In a controlled experiment, a biol- used for comparison. In this experiment, the kittiwakes ogist develops an experimental procedure not given the supplemental feedings made up the con- designed to investigate a question or problem. trol group. The experimental group is the group By manipulating variables and observing exposed to the factor being tested. The group of kitti- results, a biologist learns about relationships wakes getting the supplemental feedings made up the among factors in the experiment. experimental group. Procedure Experimental design When scientists design a 1. Read and complete the lab safety form. controlled experiment, only one factor can change at a 2. Create a data table with the columns time. It is called the independent variable because it is labeled Control, Independent Variable, Con- the tested factor and it might affect the outcome of the stants, Hypothesis, and Dependent Variable. experiment. In the kittiwakes experiment, the supplemen- 3. Obtain a printed maze. Seated at your desk, tal feeding was the independent variable. During an have a classmate time how long it takes you to complete the maze. Record this time on the experiment, scientists measure a second factor. This factor chart. This is the control in the experiment. is the dependent variable. It results from or depends on 4. Choose a way to alter experimental condi- changes to the independent variable. The change in the tions while completing the same maze. kittiwakes’ energy levels, as measured in reproductive out- Record this as the independent variable. put, was the dependent variable. A constant is a factor 5. In the column labeled Constants, list factors that remains fixed during an experiment while the inde- that will stay the same each time the experi- pendent and dependent variables change. ment is performed. 6. Form a hypothesis about how the indepen- Data gathering As scientists test their hypotheses, dent variable will affect the time it takes to they gather data—information gained from observations. complete the maze. The data can be quantitative or qualitative. 7. After your teacher approves your plan, carry Data collected as numbers are called quantitative out the experiment. Record the time data. Numerical data can be measurements of time, required to complete the maze as the temperature, length, mass, area, volume, density, or dependent variable. other factors. For example, when the biologists worked 8. Repeat Steps 3–7 as time allows. with the kittiwakes, they collected numerical data about 9. Graph the data. Use the graph to analyze the birds’ energy levels. the relationship between the independent Qualitative data are descriptions of what our and dependent variables. senses detect. Often, qualitative data are interpreted Analysis differently because everyone does not sense things 1. Explain the importance of the control in in the same way. However, many times it is the only this experiment. collectible data. 2. Error Analysis By completing the maze more than once, you introduced another Investigations Biologists conduct other kinds of variable, which likely affected the time scientific inquiry. They can engage in studies during required to complete the maze. Would which they investigate the behavior of organisms. eliminating this variable solve the problem? Other biologists spend their careers discovering and Explain. identifying new species. Some biologists use computers to model the natural behavior of organisms and sys- tems. In investigations such as these, the procedure involves observation and collection of data rather than controlled manipulation of variables. Section 3 Methods of Science 19 Change in Mass of Anole #HANGE IN -ASS OF !NOLE Date Mass (g) April 11 2.4 April 14 2.5 -ASS G April 17 2.5 April 20 2.6 April 23 2.6 April 26 2.7 April 29 2.7.UMBER OF DAYS Anole Figure 1.17 After plotting the data points from the table on graph paper, draw a line that Analyze the Data fits the pattern of the data rather than connects After analyzing the data from an investigation, a biologist usually asks, the dots. “Has my hypothesis been supported?” He or she then might ask, “Are Extrapolate What do you think the mass of the anole will be at 21 days? more data needed?” or “Are different procedures needed?” Often, the investigation must be repeated many times to obtain consistent results. As biologists look for explanations, patterns generally are noted that help to explain the data. A simple way to display the data is in a table or on a graph, such as the ones in Figure 1.17, which describe the change VOCABULARY in mass over time of a lizard called an anole. The graph of the data SCIENCE USAGE V. COMMON USAGE makes the pattern easier to grasp. In this case, there is a regular pat- Conclusion tern. Notice that the mass increases over a three-day period and then Science usage: judgment, decision, or levels off for three days before increasing again. For more review about opinion formed after an investigation. making graphs, refer to the Skillbuilder Handbook, pp. 1115–1118. The researcher formed the conclusion Because biologists often work in teams, meetings are held to discuss that the hypothesis was not supported. ongoing investigations, to analyze the data, and to interpret the results. The teams continue to examine their research plan to be certain they Common usage: the end or last part. avoid bias, repeat their trials, and collect a large enough sample size. The audience left at the conclusion of Analysis of the data might lead to a conclusion that the hypothesis has the movie. been supported. It also could lead to additional hypotheses, to further experimentation, or to general explanations of nature. Even when a hypothesis has not been supported, it is valuable. Report Conclusions Biologists report their findings and conclusions in scientific journals. Before a scientist can publish in a journal, the work is reviewed by peers. The reviewers examine the paper for originality, competence of the scientific method used, and accuracy. They might find fault with the reasoning or procedure, or suggest other explanations or conclu- sions. If the reviewers agree on the merit of the paper, then the paper is published for review by the public and use by other scientists. Reading Check Infer How does the hypothesis guide data collection and interpretation? 20 Chapter 1 The Study of Life Azure Computer & Photo Services/Animals Animals ÃÊ>Ê+ÕiÃÌ UÊ>ÛiÊÊÀi>`ÊÌ iÊiÌÀiÊ>ÕV >L]Ê>L]Ê UÊÀiÊÌ iÀiÊ>``Ì>ÊÃÌÀÕVÌÃÊvÀ ÊÊÊÀÊ >L¶ ÊÊ«iÀ>Ì}ÊÌ iÊiµÕ«iÌ¶ UÊ7 >ÌÊµÕiÃÌÊÜÊÊÌÀÞÊÌÊ>ÃÜiÀ¶ UÊ7 >ÌÊÃ>viÌÞÊ«ÀiV>ÕÌÃÊÃ Õ`ÊÊvÜ¶ UÊÃÊL>V}ÀÕ`ÊvÀ>ÌÊ«ÀÛ`i`ÊvÀÊÌ Ã UÊ iÃÊÞÊÌi>V iÀÊ>««ÀÛiÊÌ ÃÊ«ÀVi`ÕÀi¶ ÊÊÊÌ«V¶Ê7 >ÌÊ`ÊÊÜÊ>LÕÌÊÌ ÃÊÌ«V¶ UÊÜÊÜÊÊVi>ÊÕ«Ê>`Ê`Ã«ÃiÊvÊ>ÌiÀ>Ã¶ ÀÊ>ÊÞ«Ì iÃÃ >ÞâiÊÌ iÊ >Ì> UÊ7 >ÌÊÃÊÞÊ Þ«Ì iÃÃ¶ UÊÜÊÜÊÊ`Ã«>ÞÊÞÊ`>Ì>¶ UÊ iÃÊÌÊ}ÛiÊiÊ>ÊÌiÃÌ>LiÊ«Ài`VÌ¶ UÊÜÊÜÊÊ>>ÞâiÊ>`ÊÃÕ>ÀâiÊÞÊÀiÃÕÌÃ¶ iÃ¶ UÊÀiÊÌ iÀiÊ>ÞÊÃÕÀViÃÊvÊiÀÀÀÊÊÞÊ«ÀVi`ÕÀ iVÌÊÌ iÊ >Ì> UÊÜÊÜÊÊÀiVÀ`ÊÞÊ`>Ì>¶ ,i«ÀÌÊ>Ê VÕÃ UÊ7 >ÌÊÃÊÌ iÊiÝ«iÀiÌ>Ê}ÀÕ«¶Ê ÌÀÊ}ÀÕ«¶ UÊ7>ÃÊÞÊ Þ«Ì iÃÃÊÃÕ««ÀÌi`¶Ê7 ÞÊÀÊÜ ÞÊÌ¶ UÊ7 >ÌÊÃÊÌ iÊ`i«i`iÌÊÛ>À>Li¶Ê UÊ7 >ÌÊÃÊÞÊVVÕÃ¶ ÊÊ i«i`iÌÊÛ>À>Li¶ UÊ7 >ÌÊÜÊÊ `ÊVÃÌ>Ì¶ UÊ7 >ÌÊ>ÌiÀ>ÃÊ>`ÊiµÕ«iÌÊ`ÊÊii`¶ Student Scientific Inquiry Figure 1.18 To ask meaningful questions, form hypotheses, and conduct You might be given many opportunities during your study of biology to careful experiments, develop research plans do your own investigations and experiments. You might receive a lab based on scientific methods. Use your lab report assignment that spells out a series of steps to follow or you might design to list your procedure, record your data, and report your conclusions. your own procedure. Whether you are planning a lab report or an entire procedure and its lab report, be sure to ask yourself questions like those in Figure 1.18. For additional help with setting up experi- ments and using equipment, go to Investigation and Experimentation on pp. xxvii–xli of this textbook. Lab safety During biology labs, you will be alerted of possible safety hazards by warning statements and safety symbols. A safety symbol is a logo designed to alert you about a specific danger. Always refer to the safety symbols chart at the front of this book before beginning any field investigation or lab activity. Carefully read the meaning of each lab’s safety symbols. Also, learn the location in the classroom of all safety equipment and how and when to use it. You are responsible for being safe at all times to protect yourself and your classmates. I&E 1.a, 1.b, 1.c, 1.d, 1.f, 1.g, 1.j, 1.k Section 1.3 Assessment Section Summary Understand Main Ideas Think Scientifically ◗ Observations are an orderly way of 1. -!). )DEA Describe how a biol- gathering information. ogist’s research can proceed from an idea to a published article. 5. Design a controlled experiment to ◗ Inferences are based on prior determine whether earthworms are experiences. 2. State why an observation cannot more attracted to perfume or to be an inference. ◗ Controlled experiments involve a vinegar. control group and an experimental 3. Indicate the differences in the group. ways that data can be collected in 6. Form a hypothesis about one of biological research. the characteristics of life you ◗ An independent variable is the condi- 4. Differentiate between indepen- studied in Section 1.1 and design a tion being tested, and the dependent dent variables and dependent research project to test it. What variable results from the change to variables. organism would you study? What the independent variable. questions would you ask? Self-Check Quiz biologygmh.com Section 3 Methods of Science 21 Biology/Life Sciences 5.c; I&E 1.m Cancer Research Cancer Institute. With this grant, she began her research on cancerous pigment cells and the possible role of melanin in protecting the A whole new world From the first time that skin from the Sun’s ultraviolet rays—a cancer- she peered into a microscope and saw a tiny, causing agent. Skin cancer, called melanoma, fascinating new world, Jewell Plummer Cobb occurs more in Caucasians than in African Amer- knew that a career in biology was for her. It is icans. Because African Americans have more no surprise that biology would fascinate her. melanin than Caucasians, Cobb wanted to Cobb’s father was a physician, her mother was know if the melanin had protective qualities. a teacher, and science often was the topic of dinner conversation. Cobb became a ground- To determine how melanin affected the outcome breaking scientist, as well as a college dean, of radiation therapy in cancer treatments, she recipient of almost two dozen honorary degrees, designed an experiment using black and white and a champion of minority and women’s rights. mice that were bred to develop melanoma tumors. Dr. Cobb took samples from tumors and Individualized separated the tissue with high melanin from the chemotherapy tissue with low melanin. She exposed both In 1950, Dr. Cobb tissues to different doses of X rays to determine joined the Harlem if melanin protected cells against the effects of X Hospital Cancer rays. Immediately after exposure, she implanted Research Foun- the tissues into cancer-free mice or grew them dation, where she in test tubes. The black tissues survived greater pioneered chemo- X-ray doses than the white tissues. After therapy research examination with a microscope, she concluded with Jane Cooke that melanin protected cells from X-ray damage. Wright. The two scientists deter- Research ways to diagnose, treat, and prevent Jewell Plummer Cobb has devoted her life mined that there melanoma continue. For example, immuno- to cancer research. should be a way therapy uses the body’s own defenses to destroy to tailor thera- cancer cells. A melanoma might be surgically peutic drug dosages for individuals. Cobb removed from the skin or treated with chemo- designed new ways to grow tissue sam

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