Principles of life 2nd edition pdf download

Principles of life 2nd edition pdf download

Principles of Life, 2nd Edition – PDF ebook,Principles of Life 2nd Edition – PDF

The lowdown Principles Of Life 2Nd Edition on the best PDF Download that you can easily get is available at a click of a button, I would like to let you know how I did it. Don’t let the chance to learn from the best. I don’t know about you, but I can always find time for reading Principles Of Life 2Nd Edition Download Principles of Life, 2nd Edition PDF ebook, David M. Hillis, David E. Sadava, Richard W. Hill, Mary V. Price, W. H. Freeman. ISBN: Pastor Charles Stanley provides a wealth of principles to be applied practically as you read and study God’s Word. The Charles F. Stanley Life Principles Bible, with over a million sold to ISBN: Author: David M. Hillis, David E. Sadava Format: eBook (PDF/ePub) Pages: pages Publication Date: December 1, File Size: MB Language: English 06/06/ · >>>>> DOWNLOAD: Principles of life 2nd edition pdf free download Only Books - Free eBooks Download. Strategic Staffing 3rd Edition by Jean M. Phillips Stan M. Gully. ... read more

Using the standards of journal publication as a model, the author provides, in a user-friendly format, specific instructions on: using biology databases to locate references; paraphrasing for improved comprehension; preparing lab reports, scientific papers, posters; preparing oral presentations in PowerPoint, and more. Bioethics and the New Embryology: Springboards for Debate Scott F. Gilbert, Anna Tyler, and Emily Zackin ISBN Our ability to alter the course of human development ranks among the most significant changes in modern science and has brought embryology into the public domain. The question that must be asked is: Even if we can do such things, should we?

BioStats Basics: A Student Handbook James L. Gould and Grant F. Gould ISBN BioStats Basics provides introductory-level biology students with a practical, accessible introduction to statistical research. Engaging and informal, the book avoids excessive theoretical and mathematical detail, and instead focuses on how core statistical methods are put to work in biology. tion contains over 1, photographs in addition to those in the textbook , giving instructors a wealth of additional imagery to draw upon. A collection of video segments that covers topics across the entire textbook and helps demonstrate the complexity and beauty of life. For each chapter of the textbook, several different PowerPoint presentations are available. These give instructors the flexibility to build presentations in the manner that best suits their needs.

These exercises help instructors engage students in the classroom through a variety of questions and problems that include discussion questions, data analysis exercises, and more, in a format designed to be used with clicker systems. Includes a wealth of information to help instructors in the planning and teaching of their course. A visual guide to the extensive media resources available with Principles of Life. The guide includes thumbnails and descriptions of every video, animation, activity, and supplemental photo in the Media Library, all organized by chapter. TEST BANK in Microsoft Word® format for easy use in lecture and exam preparation.

Test Bank The Test Bank offers thousands of questions, covering the full range of topics presented in the textbook. Each chapter includes a wide range of multiple choice and fill-in-the-blank questions. In addition, each chapter features a set of diagram questions that involve the student in working with illustrations of structures, graphs, steps in processes, and more. Course Management System Support As a service for Principles of Life adopters using WebCT, Blackboard, or ANGEL for their courses, full electronic course packs are available. Faculty Lounge for Majors Biology is the first publisher-provided website for the majors biology community that lets instructors freely communicate and share peer-reviewed lecture and teaching resources.

It is continually updated and vetted by majors biology instructors—there is always something new to see. The Faculty Lounge offers convenient access to peer-recommended and vetted resources, including the following categories: Images, News, Videos, Labs, Lecture Resources, and Educational Research. In addition, the site includes special areas for resources for lab coordinators, resources and updates from the Scientific Teaching series of books, and information on biology teaching workshops. com Figure Correlation Tool An invaluable resource for instructors switching to Principles of Life from another textbook, this online tool provides easy correlations between the figures in Principles of Life and figures in other majors biology textbooks.

Developed for educators by educators, iclicker is a hassle-free radio-frequency classroom response system that makes it easy for instructors to ask questions, record responses, take attendance, and direct students through lectures as active participants. For more information, visit www. LabPartner is a site designed to facilitate the creation of customized lab manuals. Its database contains a wide selection of experiments published by W. Freeman and Hayden-McNeil Publishing. Instructors can preview, choose, and re-order labs, interleave their own original experiments, add carbonless graph paper and a pocket folder, and customize the cover both inside and out. LabPartner offers a variety of binding types: paperback, spiral, or loose-leaf. Manuals are printed on-demand once W. Freeman receives an order from a campus bookstore or school. The purpose of these books is to help faculty become more successful in all aspects of teaching and learning science, including classroom instruction, mentoring students, and professional development.

Authored by well-known science educators, the Series provides concise descriptions of best practices and how to implement them in the classroom, the laboratory, or the department. For readers interested in the research results on which these best practices are based, the books also provide a gateway to the key educational literature. Branchaw, Christine Pfund, and Raelyn Rediske ISBN This page intentionally left blank Table of Contents 1 Principles of Life 1 CONCEPT 1. If you are like most people, you probably notice the trees, colorful flowers, and some animals. You probably spend little time, however, thinking about how these living things function, reproduce, interact with one another, or affect their environment. An introduction to biology should inspire you to ask questions about what life is, how living systems work, and how the living world came to be as we observe it today. Biologists have amassed a huge amount of information about the living world, and some introductory biology classes focus on memorizing these details.

This book takes a different approach, focusing on the major principles of life that underlie everything in biology. What do we mean by principles of life? Consider the photograph. Why is the view so overwhelmingly green? The color is explained by a fundamental principle of life, namely that all living organisms require energy in order to grow, move, reproduce, and maintain their bodies. Ultimately, most of that energy comes from the sun. The green leaves of plants contain chlorophyll, a pigment that captures energy from the sun and uses it to transform water and carbon dioxide into sugar and oxygen a process called photosynthesis.

That sugar can then be broken down again by the plant, or by other organisms that eat the plant, to provide energy. The frog in the photograph is using energy to grasp the trunk of the tree. That energy came from molecules in the bodies of insects eaten by the frog. The frog, like the plants, is ultimately solar-powered. The photograph illustrates other principles of biology. You probably noticed the frog and the trees in the photograph above, but did you notice the patches of growth on the trunk of the tree? Most of those are lichens, a complex interaction between a fungus and a photosynthetic organism in this case, a species of algae. Living organisms often survive and thrive by interacting with one another in complex ways.

In lichen, the fungus and the alga live in an obligate symbiosis, meaning that they depend on each other for survival. Many other organisms in this scene are too small to be seen, but they are critical components for keeping this living system functioning over time. After reading this book, you should understand the main principles of life. May a walk in the park never be the same for you again! KEY CONCEPTS 1. We can image other origins, perhaps on other planets, of self-replicating systems that have properties similar to life as we know it. But the evidence suggests that all of life on Earth today has a single origin—a single common ancestor—and we consider all the organisms that descended from that common ancestor to be a part of life.

Life as we know it had a single origin The overwhelming evidence for the common ancestry of life lies in the many distinctive characteristics that are shared by all living organisms. Life appeared some time around day 5, a little less than 4 billion years ago. First life? FIGURE 1. If we were to discover an independent origin of a similar self-replicating system i. Organisms from another origin of life might be similar in some ways to life on Earth, such as using genetic information to reproduce. But we would not expect the details of their genetic code or the fundamental sequences of their genomes to be like ours.

The simple list of characteristics above, however, is an inadequate description of the incredible complexity and diversity of life. Some forms of life may not even display all of these characteristics all of the time. For example, the seed of a desert plant may go for many years without extracting energy from the environment, converting molecules, regulating its internal environment, or reproducing; yet the seed is alive. And what about viruses? Viruses do not consist of cells, and they cannot carry out the functions of life enumerated in the list above on their own; they must parasitize host cells to do those jobs for them.

Yet viruses contain genetic information and use the same basic genetic code and amino acids as do other living things, and they certainly mutate and evolve. The existence of viruses depends on cells, and there is strong evidence that viruses evolved from cellular life forms. So, although viruses are not independent cellular organisms, they are a part of life and are studied by biologists. This book explores the characteristics of life, how these characteristics evolved and how they vary among organisms, and how they work together to enable organisms to survive and reproduce. Recorded history covers the last few seconds of day At first, the planet was not a very hospitable place.

It was some million years or more before the earliest life evolved. If we picture the history of Earth as a day month, life first appeared somewhere toward the end of the first week FIGURE 1. Biologists postulate that complex biological molecules first arose through the random physical association of chemicals in that environment. Experiments simulating the conditions on early Earth have confirmed that the generation of complex molecules under such conditions is possible, even probable. The critical step for the evolution of life, however, was the appearance of nucleic acids—molecules that could reproduce themselves and also serve as templates for the synthesis of large molecules with complex but stable shapes. The variation in the shapes of these large, stable molecules—proteins—enabled them to participate in increasing numbers and kinds of chemical reactions with other molecules. Cellular structure evolved in the common ancestor of life The next step in the origin of life was the enclosure of complex proteins and other biological molecules by membranes that contained them in a compact internal environment separate from the surrounding external environment.

Molecules called fatty acids played a critical role because these molecules do not dissolve in water; rather, they form membranous films. When agitated, these films can form spherical vesicles, which could have enveloped assemblages of biological molecules. The creation of an internal environment that concentrated the reactants and products of chemical reactions opened up the possibility that those reactions could be integrated and controlled within a tiny cell. Scientists postulate that this natural process of membrane formation resulted in the first cells with the ability to reproduce—the evolution of the first cellular organisms.

For more than 2 billion years after cells originated, every organism consisted of only one cell. These first unicellular organisms were and are, as multitudes of their descendants exist in similar form today prokaryotes. Prokaryotic cells consist of Haloferax mediterranei Membrane This prokaryotic organism synthesizes and stores carbon-containing molecules that nourish and maintain it in harsh environments. genetic material and other biochemicals enclosed in a membrane FIGURE 1. Early prokaryotes were confined to the oceans, where there was an abundance of complex molecules they could use as raw materials and sources of energy. The ocean shielded them from the damaging effects of ultraviolet UV light, which was intense at that time because there was little or no oxygen O2 in the atmosphere, and hence no protective ozone O3 layer in the upper atmosphere.

Photosynthesis allowed living organisms to capture energy from the sun To fuel their cellular metabolism, the earliest prokaryotes took in molecules directly from their environment and broke these small molecules down to release and use the energy contained in their chemical bonds. Many modern species of prokaryotes still function this way, and very successfully. About 2. The chemical reactions of photosynthesis transform the energy of sunlight into a form of biological energy that can power the synthesis of large molecules. These large molecules are the building blocks of cells, and they can be broken down to provide metabolic energy. Photosynthesis is the basis of much of life on Earth today because its energy-capturing processes provide food for other organisms. Early photosynthetic cells were probably similar to present-day prokaryotes called cyanobacteria FIGURE 1.

Over time, photosynthetic prokaryotes became so abundant that vast quantities of O2, which is a by-product of photosynthesis, slowly began to accumulate in the atmosphere. During the early eons of life on Earth, there was no O2 in the atmosphere. In fact, O2 was poisonous to many of the prokaryotes that lived at that time. Those organisms that did tolerate O2, however, were able to proliferate, and the presence of O2 opened up vast new avenues of evolution. Aerobic metabolism energy production using O2 is more efficient than anaerobic non-O2-using metabolism, and it allowed organisms to grow larger.

Aerobic metabolism is used by the majority of living organisms today. Oxygen in the atmosphere also made it possible for life to move onto land. But the accumulation of photosynthetically generated O2 in the atmosphere for more than 2 billion years gradually produced a layer of ozone in the upper atmosphere. Today all organisms, even the largest and most complex, are made up of cells. Unicellular organisms such as this one, however, remain the most abundant living organisms in absolute numbers on Earth. If the larger cell failed to break down this intended food object, a partnership could have evolved in which the ingested prokaryote provided the products of photosynthesis and the host cell provided a good environment for its smaller partner. Multicellularity allowed specialization of tissues and functions B For the first few billion years of life, all the organisms that existed—whether prokaryotic or eukaryotic—were unicellular.

At some point, the cells of some eukaryotes failed to separate after cell division, remaining attached to each other. Such permanent colonial aggregations of cells made it possible for some of the associated cells to specialize in certain functions, such as reproduction, while other cells specialized in other functions, such as absorbing nutrients. Cellular specialization enabled multicellular eukaryotes to increase in size and become more efficient at gathering resources and adapting to specific environments. Biologists can trace the evolutionary tree of life FIGURE 1. A Colonies of cyanobacteria called stromatolites are known from the ancient fossil record. B Living stromatolites are still found in appropriate environments on Earth today. Eukaryotic cells evolved from prokaryotes Another important step in the history of life was the evolution of cells with membrane-enclosed compartments called organelles, within which specialized cellular functions could be performed away from the rest of the cell.

The first organelles probably appeared about 2. And chloroplasts—the organelles specialized to conduct If all the organisms on Earth today are the descendants of a single kind of unicellular organism that lived almost 4 billion years ago, how have they become so different? Organisms reproduce by replicating their genomes, as we will discuss shortly. This replication process is not perfect, however, and changes, called mutations, are introduced almost every time a genome is replicated. Some mutations give rise to structural and functional changes in organisms. As individuals mate with one another, these changes can spread within a population, but the population will remain one species. However, if something happens to isolate some members of a population from the others, structural and functional differences between the two groups will accumulate over time.

The two groups may diverge to the point where their members can no longer reproduce with each other; thus the two populations become distinct species. Tens of millions of species exist on Earth today. Many times that number lived in the past but are now extinct. Biologists give each of these species a distinctive scientific name formed from two Latinized words—a binomial. The second is the name of the species. For example, the scientific name for the human species is Homo sapiens: Homo is our genus and sapiens our species. Much of biology is based on comparisons among species, and these comparisons are useful precisely because we can place species in an evolutionary context relative to one another. Our ability to do this has been greatly enhanced in recent decades by our ability to sequence and compare the genomes 1.

Endosymbiotic, photosynthetic bacteria became chloroplasts. Chloroplasts Life Estimated total number of living species BACTERIA 10, Millions ARCHAEA 1,— 1 million Mitochondria , ,— , 80, ,— 1 million 1,, 10 million— million 98, 1—2 million Plants Protists FIGURE 1. The darkest blue branches within Eukarya represent various groups of microbial protists. Animals, plants, and fungi are examples of multicellular eukaryotes that have evolved independently from the protists. In this book, we adopt the convention that time flows from left to right, so this tree and other trees in this book lies on its side, with its root—the common ancestor—at the left. com Number of known described species Protists Protists Protists Protists Protists EUKARYA Go to WEB ACTIVITY 1. Genome sequencing and other molecular techniques have allowed biologists to augment evolutionary knowledge based on the fossil record with a vast array of molecular evidence. The result is the ongoing compilation of phylogenetic trees that document and diagram evolutionary relationships as part of an overarching tree of life, the broadest categories of which are shown in FIGURE 1.

Although many details remain to be clarified, the broad outlines of the tree of life have been determined. Its branching patterns are based on a rich array of evidence from fossils, structures, metabolic processes, behavior, and molecular analyses of genomes. Molecular data in particular have been used to separate the tree into three major domains: Archaea, Bacteria, and Eukarya. The organisms of each domain have been evolving separately from those in the other domains for more than a billion years. Organisms in the domains Archaea and Bacteria are singlecelled prokaryotes. However, members of these two groups differ so fundamentally in their metabolic processes that they are believed to have separated into distinct evolutionary lineages very early. Species belonging to the third domain— Eukarya—have eukaryotic cells whose mitochondria and chloroplasts originated from endosymbioses of bacteria.

Plants, fungi, and animals are examples of familiar multicellular eukaryotes that evolved from different groups of Animals Fungi unicellular eukaryotes, informally known as protists. We know that these three groups as well as others had independent origins of multicellularity because they are each most closely related to different groups of unicellular protists, as can be seen from the branching pattern of Figure 1. Discoveries in biology can be generalized Because all life is related by descent from a common ancestor, shares a genetic code, and consists of similar molecular building blocks, knowledge gained from investigations of one type of organism can, with care, be generalized to other organisms.

Biologists use model systems for research, knowing they can extend their findings to other organisms, including humans. Our basic understanding of the chemical reactions in cells came from research on bacteria but is applicable to all cells, including those of humans. Similarly, the biochemistry of photosynthesis—the process by which plants use sunlight to produce sugars—was largely worked out from experiments on Chlorella, a unicellular green alga. Much of what we know about the genes that control plant development is the result of work on Arabidopsis thaliana, a relative of the mustard plant.

Knowledge about how animals develop has come from work on sea urchins, frogs, chickens, roundworms, and fruit flies. And recently, the discovery of a major gene controlling human skin color came from work on zebrafish. Being able to generalize from model systems is a powerful tool in biology. C G T A DNA is made up of two strands of linked sequences of nucleotides. Nucleic acid molecules contain long sequences of four subunits called nucleotides. The sequence of these nucleotides in deoxyribonucleic acid, or DNA, allows the organism to make proteins. Each gene is a specific segment of DNA whose sequence carries the information for building or controlling the expression of one or more proteins FIGURE 1. By analogy with a book, the nucleotides of DNA are like the letters of an alphabet. The sentences of the book are genes that describe proteins, or provide instructions for making the proteins at a particular time or place.

If you were to write out your own genome using four letters to represent the four DNA nucleotides, you would write more than 3 billion letters. Using the size type you are reading now, your genome would fill more than a thousand books the size of this one. All the cells of a given multicellular organism contain the same genome, yet the different cells have different functions and form different proteins—hemoglobin forms in red blood cells, gut cells produce digestive proteins, and so on. Therefore, different types of cells in an organism must express different parts of the genome. How any given cell controls which genes it expresses and which genes it suppresses is a major focus of current biological research. A gene consists of a specific sequence of nucleotides. Gene DNA Protein The nucleotide sequence in a gene contains the information to build a specific protein. Specific DNA nucleotide sequences comprise genes. The average length of a single human gene is 27, nucleotides. The information in each gene provides the cell with the information it needs to manufacture molecules of a specific protein.

The genome of an organism contains thousands of genes. If mutations alter the nucleotide sequence of a gene, the protein that the gene encodes is often altered as well. Mutations may occur spontaneously, as happens when mistakes occur during replication of DNA. Mutations can also be caused by certain chemicals such as those in cigarette smoke and radiation Organism A Atoms to organisms Small molecules Large molecules, proteins, nucleic acids Cells Cell specialization Atoms Oxygen Tissues Water Methane Colonial organisms Organs Carbon Hydrogen Organ systems Carbon dioxide Unicellular organisms Multicellular organism leopard frog 1.

Most mutations are either harmful or have no effect, but occasionally a mutation improves the functioning of the organism under the environmental conditions the individual encounters. Mutations are the raw material of evolution. Organisms Interact with and Affect Their Environments 7 The vast amount of information being collected from genome studies has led to rapid development of the field of bioinformatics, or the study of biological information. In this emerging field, biologists and computer scientists work in close association to develop new computational tools to organize, process, and study comparative genomic databases. This first sequence was that of a virus, and viral genomes are very small compared with those of most cellular organisms.

It was another two decades before the first bacterial genome was sequenced, in The first animal genome a relatively small one, that of a roundworm was determined in late A massive effort to sequence the complete human genome began in and culminated 13 years later. Since then, the methods developed in these pioneering projects as well as new DNA sequencing technologies that appear each year have resulted in the sequencing of genomes from hundreds of species. As methods have improved, the cost and time for sequencing a complete genome have dropped dramatically. Many biologists expect the routine sequencing of genomes from individual organisms to be commonplace in biological applications of the near future.

What are we learning from genome sequencing? One surprise came when some genomes turned out to contain many fewer genes than expected—for example, there are only about 24, different genes that encode proteins in a human genome, whereas most biologists had expected many times more. Gene sequence information is a boon for many areas of biology, making it possible to study the genetic basis of everything from physical structure to the basis of inherited diseases. Biologists can also compare genomes from many species to learn how and why one species differs from another. Such studies allow biologists to trace the evolution of genes through time and to document how particular changes in gene sequence result in changes in structure and function. concept 1. Biological systems are organized in a hierarchy from basic building blocks to complete functioning ecosystems of living and nonliving components FIGURE 1.

Traditionally, each biologist concentrated on understanding a particular level of this hierarchy. Today, however, much of biology involves integrating investigations across many of the hierarchical levels. com Go to WEB ACTIVITY 1. Life depends on thousands of biochemical reactions that occur inside cells, and nutrients supply the organism with the energy and FIGURE 1. B Organisms exist in populations and interact with other populations to form communities, which interact with the physical environment to make up ecosystems. Biosphere B Organisms to ecosystems Ecosystem Community Population 8 Chapter 1 Principles of Life raw materials to carry out these chemical transformations.

Some of the reactions break down nutrient molecules into smaller chemical units, and in the process some of the energy contained in the chemical bonds of the nutrients is captured by molecules that can be used to do different kinds of cellular work. The most basic cellular work is the building, or synthesis, of new complex molecules and structures from smaller chemical units. For example, we are all familiar with the fact that carbohydrates eaten today may be deposited in the body as fat tomorrow. Another kind of work that cells do is mechanical—moving molecules from one cellular location to another, moving whole cells or tissues, or even moving the organism itself, as the proteins in muscle cells do. Still another kind of work is the electrical work that is the essence of information processing in nervous systems, such as vision recall that you are using captured solar energy to read this book. The sum total of all the chemical transformations and other work done in all the cells of an organism is called metabolism.

The many biochemical reactions constantly taking place in cells are integrally linked in that the products of one are the raw materials of the next. Organisms regulate their internal environment The cells of multicellular organisms are specialized, or differentiated, to contribute in some way to maintaining the internal environment. With the evolution of specialization, differentiated cells lost many of the functions carried out by single-celled organisms. To accomplish their specialized tasks, assemblages of differentiated cells are organized into tissues. For example, a single muscle cell cannot generate much force, but when many cells combine to form the tissue of a working muscle, considerable force and movement can be generated.

Different tissue types are organized to form organs that accomplish specific functions. The heart, brain, and stomach are each constructed of several types of tissues, as are the roots, stems, and leaves of plants. Organs whose functions are interrelated can be grouped into organ systems; the stomach, intestine, and esophagus are parts of the digestive system. The functions of cells, tissues, organs, and organ systems are all integral to the multicellular organism. The specialized organ systems of multicellular organisms exist in an internal environment that is acellular i. The individual cells of a body are surrounded by an extracellular environment of fluids, from which the cells receive nutrients and into which they excrete waste products of metabolism. The maintenance of a narrow range of conditions in this internal environment is known as homeostasis. Physiological regulatory systems are especially well developed in animals, but they exist in other organisms as well.

For example, when conditions are hot and dry, plants can close the small pores called stomata on the surfaces of their leaves, thereby reducing moisture loss. When external conditions become favorable again, the plants open their stomata, allowing carbon dioxide—which is necessary for photosynthesis—to enter the leaf. This regulatory system is a simple example of a feedback loop: cells in the root of the plant the sensors release a chemical when they become dehydrated, and this chemical causes the cells around the stomata to shrink, thereby closing the pores. If external conditions improve and the cells in the root become hydrated again, the sensor cells stop releasing the chemical and the stomata open.

The concept of homeostasis extends beyond the regulation of the internal, acellular environment of multicellular organisms. Individual cells in both unicellular and multicellular organisms also regulate their internal environment through the actions of a plasma membrane, which forms the outer surface of the cell. Thus self-regulation of a more or less constant internal environment is a general attribute of living organisms. Organisms interact with one another Organisms do not live in isolation, and the internal hierarchy of the individual organism is matched by the external hierarchy of the biological world see Figure 1. A group of individuals of the same species that interact with one another is a population, and populations of all the species that live and interact in the same area are called a community. Communities together with their abiotic nonliving environment constitute an ecosystem. Individuals in a population interact in many different ways.

Animals eat plants and other animals usually members of another species and compete with other species for food and other resources. Some animals will prevent other individuals of their own species from exploiting a resource, be it food, nesting sites, or mates. Animals may also cooperate with members of their species, forming social units such as a termite colony or a flock of birds. Such interactions have resulted in the evolution of social behaviors such as communication and courtship displays. Plants also interact with their external environment, which includes other plants, fungi, animals, and microorganisms. All terrestrial plants depend on partnerships with fungi, bacteria, and animals. Some of these partnerships are necessary to obtain nutrients, some to produce fertile seeds, and still others to disperse seeds. Plants compete with each other for light and water, and they have ongoing evolutionary interactions with the animals that eat them.

Through time, many adaptations have evolved in plants that protect them from predation such as thorns or that help then attract the animals that assist in their reproduction such as sweet nectar or colorful flowers. The interactions of populations of plant and animal species in a community are major evolutionary forces that produce specialized adaptations. Communities interacting over a broad geographic area with distinguishing physical features form ecosystems; examples might include the Arctic tundra, a coral reef, or a tropical rainforest. The ways in which species interact with one another and with their environment in communities and in ecosystems is the subject of ecology. A common set of evolutionary mechanisms applies to populations of all organisms. The constant change that occurs among these populations gives rise to all the diversity we see in life. These two themes—unity and diversity—provide a framework for organizing and thinking about biological systems.

The similarities of life allow us to make comparisons and predictions from one species to another, and the differences are what make biology such a rich and exciting field for investigation and discovery. Natural selection is an important mechanism of evolution Charles Darwin compiled factual evidence for evolution in his book On the Origin of Species. Darwin also proposed one of the most important processes that produce evolutionary change. He argued that differential survival and reproduction among individuals in a population, which he termed natural selection, could account for much of the evolution of life.

Although Darwin proposed that living organisms are descended from common ancestors and are therefore related to A Dyscophus guineti B Xenopus laevis Evolution Explains Both the Unity and Diversity of Life 9 one another, he did not have the advantage of understanding the mechanisms of genetic inheritance. But he knew that offspring differed from their parents, even though they showed strong similarities. Any population of a plant or animal species displays variation, and if you select breeding pairs on the basis of some particular trait, that trait is more likely to be present in their offspring than in the general population. Darwin himself bred pigeons, and was well aware of how pigeon fanciers selected breeding pairs to produce offspring with unusual feather patterns, beak shapes, or body sizes.

He realized that if humans could select for specific traits, the same process could operate in nature; hence the term natural selection as opposed to the artificial human-imposed selection that has been practiced on crop plants and domesticated animals since the dawn of human civilization. How does natural selection function? Darwin postulated that different probabilities of survival and reproductive success could account for evolutionary change. He reasoned that the reproductive capacity of plants and animals, if unchecked, would result in unlimited growth of populations, but we do not observe such growth in nature; in most species, only a small percentage of offspring survive to reproduce. Thus any trait that confers even a small increase in the probability that its possessor will survive and reproduce will spread in the population.

Consider the feet of the frog shown in the opening photograph of this chapter. Expanded toes increase the ability of tree frogs to climb trees, which allows them to seek insects for food in the forest canopy and to escape terrestrial predators. Thus the expanded toe pads of tree frogs are an adaptation to arboreal life. C Agalychnis callidryas D Rhacophorus nigropalmatus FIGURE 1. A This terrestrial frog walks across the ground using its short legs and peglike digits toes. B Webbed rear feet are evident in this highly aquatic species of frog. C This arboreal species has toe pads, which are adaptations for climbing. D A different arboreal species has extended webbing between the toes, which increases surface area and allows the frog to glide from tree to tree.

These processes operating over evolutionary history have led to the remarkable array of life on Earth. Everything in biology is a product of evolution, and biologists need to incorporate a perspective of change and adaptation to fully understand biological systems. Evolution can be observed and measured directly, and many biologists conduct experiments on evolving populations. We constantly observe changes in the genetic composition of populations over relatively short-term time frames. In addition, we can directly observe a record of the history of evolution in the fossil record over the almost unimaginably long periods of geological time. Exactly how biological populations change through time is something that is subject to testing and experimentation.

The fact that biological populations evolve, however, is not disputed among biologists You will see evolution and the other major principles of life described in this chapter at work in each part of this book. In Part I you will learn about the molecular structure of life. We will discuss the origin of life, the energy inherent in atoms and molecules, and how proteins and nucleic acids became the selfreplicating cellular systems of life. Part II will describe how these self-replicating systems work and the genetic principles that explain heredity and mutation, which are the building blocks of evolution. In Part III we will describe the mechanisms of evolution and go into greater detail about how evolution works.

Part IV will examine the products of evolution: the vast diversity of life and the many different ways organisms solve some common problems such as reproducing, defending themselves, and obtaining nutrients. Parts V and VI will explore the physiological adaptations that allow plants and animals to survive and function in a wide range of physical environments. Finally, in Part VII we will discuss these environments and the integration of individual organisms, populations, and communities into the interrelated ecosystems of the biosphere. You may enjoy returning to this chapter occasionally as the course progresses; the necessarily terse explanations given here should begin to cohere and make more sense as you read about the facts and phenomena that underlie the principles. Scientific knowledge is based on active and always-ongoing research. In both, scientists are guided by established principles of a set of scientific methods that allow us to discover new aspects about the structure, function, and history of the natural world.

Observing and quantifying are important skills Many biologists are motivated by their observations of the living world. Learning what to observe in nature is a skill that develops with experience in biology. An intimate understanding of the natural history of a group of organisms—how the organisms get their food, reproduce, behave, regulate their internal environments their cells, tissues, and organs , and interact with other organisms—facilitates observations and leads biologists to ask questions about those observations. The more a biologist knows about general principles, the more he or she is likely to gain new insights from observing nature.

Biologists have always observed the world around them, but today our ability to observe is greatly enhanced by technologies such as electron microscopes, rapid genome sequencing, magnetic resonance imaging, and global positioning satellites. These technologies allow us to observe everything from the distribution of molecules in the body to the daily movement of animals across continents and oceans. Observation is a basic tool of biology, but as scientists we must also be able to quantify our observations. Whether we are testing a new drug or mapping the migrations of the great whales, mathematical and statistical calculations are essential. For example, biologists once classified organisms based entirely on qualitative descriptions of the physical differences among them. There was no way of objectively determining evolutionary relationships of organisms, and biologists had to depend on the fossil record for insight. Today our ability to quantify the molecular and physical differences among species, combined with explicit mathematical models of the evolutionary process, enables quantitative analyses of evolutionary history.

Science Is Based on Quantifiable Observations and Experiments 1. This is an oversimplification. Although such flow charts incorporate much of what scientists do, you should not conclude that scientists necessarily progress through the steps of the process in one prescribed, linear order. Observations lead to questions, and scientists make additional observations and often do experiments to answer those questions. This approach, called the hypothesis—prediction method, has five steps: 1 making observations; 2 asking questions; 3 forming hypotheses, or tentative answers to the questions; 4 making predictions based on the hypotheses; and 5 testing the predictions by making additional observations or conducting experiments.

These are the steps seen in traditional flow charts such as the one shown in FIGURE 1. After posing a question, a scientist often uses inductive logic to propose a tentative answer. Inductive logic involves taking observations or facts and creating a new proposition that is compatible with those observations or facts. Such a tentative proposition is called a hypothesis. In formulating a hypothesis, 1. Make observations. The next step in the scientific method is to apply a different form of logic—deductive logic—to make predictions based on the hypothesis.

Deductive logic starts with a statement believed to be true and goes on to predict what facts would also have to be true to be compatible with that statement. Amphibians—such as the frog in the opening photograph of this chapter—have been around for a long time. They watched the dinosaurs come and go. Biologists work to answer general questions like this by making observations and doing experiments. There are probably multiple reasons that amphibian populations are declining, but scientists often break up a large problem into many smaller problems and investigate them one at a time. One hypothesis is that frog populations have been adversely affected by agricultural insecticides and herbicides weed-killers. Several studies have shown that many of these chemicals tested at realistic concentrations do not kill amphibians. But Tyrone Hayes, a biologist at the University of California at Berkeley, probed deeper.

com 2. Speculate, ask a question. Go to ANIMATED TUTORIAL 1. Form a hypothesis to answer the question. Revise your hypothesis. Make a prediction: What else would be true if your hypothesis is correct? Design and conduct an experiment that uses quantifiable data to test your prediction. Reexamine the experiment for uncontrolled variables. Use statistical tests to evaluate the significance of your results. Significant results support hypothesis. Experiment repeated and results verified by other researchers. Results do not support hypothesis. Hayes focused on atrazine, the most widely used herbicide in the world and a common contaminant in fresh water.

More than 70 million pounds of atrazine are applied to farmland in the United States every year, and it is used in at least 20 countries. Atrazine kills several types of weeds that can choke fields of important crops such as corn. The chemical is usually applied before weeds emerge in the spring—at the same time many amphibians are breeding and thousands of tadpoles swim in the ditches, ponds, and streams that receive runoff from farms. In his laboratory, Hayes and his associates raised frog tadpoles in water containing no atrazine and in water with concentrations ranging from 0. The U. Environmental Protection Agency considers environmental levels of atrazine of 10—20 ppb of no concern; it considers 3 ppb a safe level in drinking water.

Rainwater in Iowa has been measured to contain 40 ppb. In Switzerland, where the use of atrazine is illegal, the chemical has been measured at approximately 1 ppb in rainwater. Answers gleaned through experimentation lead to new questions, more hypotheses, further experiments, and expanding knowledge. In some of the adult males that developed from these larvae, the vocal structures used in mating calls were smaller than normal, female sex organs developed, and eggs were found growing in the testes. In other studies, normal adult male frogs exposed to 25 ppb had a tenfold reduction in testosterone levels and did not produce sperm.

You can imagine the disastrous effects these developmental and hormonal changes could have on the capacity of frogs to breed and reproduce. Would his results be the same in nature? To find out, he and his students traveled across the middle of North America, sampling water and collecting frogs. They analyzed the water for atrazine and examined the frogs. In the only site where atrazine was undetectable in the water, the frogs were normal; in all the other sites, male frogs had abnormalities of the sex organs. Like other biologists, Hayes made observations. He then made predictions based on those observations, and designed and carried out experiments to test his predictions. Some of the conclusions from his experiments, described below, could have profound implications not only for amphibians but also for other animals, including humans. Eggs from leopard frogs Rana pipiens raised specifically for laboratory use were allowed to hatch and the tadpoles were separated into experimental tanks containing water with different concentrations of atrazine.

METHOD 1. Establish 3 atrazine conditions 3 replicate tanks per condition : 0 ppb control condition , 0. Place Rana pipiens tadpoles from laboratory-reared eggs in the 9 tanks 30 tadpoles per replicate. When tadpoles have transitioned into adults, sacrifice the animals and evaluate their reproductive tissues. Test for correlation of degree of atrazine exposure with the presence of abnormalities in the gonads testes of male frogs. The most informative experiments are those that have the ability to show that the prediction is wrong. If the prediction is wrong, the hypothesis must be questioned, modified, or rejected. There are two general types of experiments, both of which compare data from different groups or samples. A controlled experiment manipulates one or more of the factors being tested; comparative experiments compare unmanipulated data gathered from different sources.

In a controlled experiment, we start with groups or samples that are as similar as possible. We predict on the basis of our hypothesis that some critical factor, or variable, has an effect on the phenomenon we are investigating. If the predicted difference occurs, we then apply statistical tests to ascertain the probability that the manipulation created the difference as opposed to the difference being the result of random chance. The basis of controlled experiments is that one variable is manipulated while all others are held constant. The variable that is manipulated is called the independent variable, and the response that is measured is the dependent variable. A good Oocytes eggs in normalsize testis sex reversal 40 In the control condition, only one male had abnormalities.

The effect is not proportional to the level of exposure. For more, go to Working with Data 1. Go to yourBioPortal. controlled experiment is not easy to design because biological variables are so interrelated that it is difficult to alter just one. A comparative experiment starts with the prediction that there will be a difference between samples or groups based on the hypothesis. In comparative experiments, however, we cannot control the variables; often we cannot even identify all the variables that are present. We are simply gathering and comparing data from different sample groups.

They collected frogs and water samples from eight widely separated sites across the United States and compared the incidence of abnormal frogs from environments with very different levels of atrazine FIGURE 1. Of course, the sample sites differed in many ways besides the level of atrazine present. The results of experiments frequently reveal that the situation is more complex than the hypothesis anticipated, thus raising new questions. As a result, biologists often develop new questions, hypotheses, and experiments as they collect more data. Statistical methods are essential scientific tools Whether we do comparative or controlled experiments, at the end we have to decide whether there is a difference between the samples, individuals, groups, or populations in the study.

How do we decide whether a measured difference is enough to support or falsify a hypothesis? In other words, how do we decide in an unbiased, objective way that the measured difference is significant? Significance can be measured with statistical methods. Scientists use statistics FIGURE 1. Hayes lab collected frogs and water samples from different locations around the U. ment could be due to random variation. A statistical test starts with a with gonadal abnormalities in frog populations. null hypothesis—the premise that any obMETHOD served differences are simply the result of 1.

Based on commercial sales of atrazine, select 4 sites sites 1—4 less likely and 4 sites random differences that arise from draw sites 5—8 more likely to be contaminated with atrazine. ing two finite samples from the same pop2. Visit all sites in the spring i. When quantified observations, or collect frogs and water samples. data, are collected, statistical methods are 3. In the laboratory, sacrifice frogs and examine their reproductive tissues, documenting applied to those data to calculate the likeabnormalities. Analyze the water samples for atrazine concentration the sample for site 7 was not tested. Skip to content Selected: Principles of Life 2nd…. Principles of Life 2nd Edition - PDF quantity. SKU: Category: Biology. You can see the screenshot attached below Note: This is an eBook and will not include the code to access online course content such as video, audio, and homework. Handling Time: Instant File Expiration: Never How it works: You will both be redirected to the download page and receive an email once you finish the checkout process.

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Buy Principles of Life, 2nd Edition PDF ebook , ISBN , copyright by author David M. Hillis, David E. Sadava, Richard W. Hill, Mary V. Price — published by W. With PDF version of this textbook, not only save you money, you can also highlight, add text, underline add post-it notes, bookmarks to pages, instantly search for the major terms or chapter titles, etc. You can search our site for other versions of the Principles of Life, 2nd Edition PDF ebook. You can also search for others PDF ebooks from publisher W. Freeman , as well as from your favorite authors. We have thousands of online textbooks and course materials mostly in PDF that you can download immediately after purchase. With its first edition, Principles of Life provided a textbook well aligned with the recommendations proposed in BIO Transforming Undergraduate Education for Future Research Biologists and Vision and Change in Undergraduate Biology Education. Now Principles of Life returns in a thoroughly updated new edition that exemplifies the reform that is remaking the modern biology classroom.

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KEY CONCEPTS 1. These tutorial modules help students understand key concepts through the use of problem scenarios, experimental techniques, and interactive models. Each Study Guide chapter also concludes with a Test Yourself section that allows the student to test their comprehension. Some forms of life may not even display all of these characteristics all of the time. At the City of Hope, his current work focuses on new anti-cancer agents from plants.

They watched the dinosaurs come and go. Evolution can be observed and measured directly, and many biologists conduct experiments on evolving populations. For more information, visit www. HillisDavid E. He realized that if humans could select for specific traits, the same process could operate in nature; hence the term natural selection as opposed to the artificial human-imposed selection that has been practiced on crop plants and domesticated animals since the dawn of human civilization. Some of the reactions break down nutrient molecules into smaller chemical units, and in the process some of principles of life 2nd edition pdf download energy contained in the chemical bonds of the nutrients is captured by molecules that can be used to do different kinds of cellular work. You probably spend little time, however, thinking about how these living things function, reproduce, interact with one another, or affect their environment.