We first began work on this text in 1982, over twenty years ago. We set out to write a text that explained biology the way we taught it in the classroom—as the product of evolution. Most texts in 1982 relegated evolution to a few chapters in the diversity section. But evolution pervades biology, and is just as evident in the bacterial character of the mitochondria within your cells, in the biochemical similarities of photosynthesis and glycolysis, in the evolution of genes that control development—everywhere you look in biology, you see Darwin staring back at you. This evolutionary approach has proven popular among our nation's biology faculty, and most texts to greater or lesser degrees now adopt it.

Our text has changed a lot over twenty years, reflecting great changes in biology. The book has become more molecular, as biology has. In particular, a lot more is said about cell biology and development, areas where biology has made enormous strides. But our text remains fundamentally an evolutionary explanation of biology. In this edition, for example, while there is a new chapter on genomes, there is also a new "evo-devo" chapter that examines how genomes and developmental control mechanisms have evolved. This is just one example of our efforts to integrate biological questions and approaches at multiple levels of organization throughout the text, as we strive to guide students toward a connected understanding of biology.

This new seventh edition marks perhaps the greatest change in our text: the addition of two new biologists to the author team, Jonathan Losos, also at Washington University, and Susan Singer of Carleton College. Both made major contributions to the previous edition—Jonathan to the chapter on evolution and ecology, and Susan to the chapters on plant biology—and we are delighted to welcome them as full-fledged authors. In this edition their responsibilities have broadened to include the revolution that is ongoing in our understanding of systematics and evolution at the DNA level, matters that affect many chapters of this book.

Text development today involves an even greater number of people, as instructors from across the country are continually invited to share their knowledge and experience with us through reviews and focus groups. All of the feedback we have received has shaped this edition, resulting in new chapters, reorganization of the table of contents, and expanded coverage in key areas. This edition also incorporated the expertise of three consultants: Randy Di Domenico, University of Colorado—Boulder; Kenneth Mason, Purdue University; and Randall Phillis, University of Massachusetts—Amherst, who provided detailed suggestions for improving the clarity, flow and accuracy of large portions of the text.

How We Have Responded to You

Perhaps more than any other text on the market, this text has continued to evolve as a result of feedback from instructors teaching majors' biology. Overwhelmingly, they have told us that up-to-date content, a clear writing style, quality illustrations and dynamic presentation materials are the most important factors they consider when evaluating textbooks. We have let those values guide our revision of the text, as McGraw-Hill Education worked with those same instructors to create supplements that will help them in the classroom.

Up-to-date Treatment

The core of any majors' biology course is the exploration of cells and genetics, always covered in the first half of any majors' text. This book has been particularly aggressive in keeping its treatment of cell biology and genetics comprehensive and up-to-date. It was the first to present a chapter on cell communication, for example (other books soon followed). We are continuing in that tradition by incorporating such cutting edge topics as the structure of ATP synthetase, small RNAs and RNA editing. This edition also includes a new chapter 17 that explores what we can learn about genomes, covering topics ranging from human health issues and concerns about privacy, agricultural applications, and the potential of genomics in minimizing bioterrorism.

We did not contain this revision to a few select chapters in the first half of the text, however, and it's possible to point to many areas where treatment of recent breakthroughs has been integrated. By concluding our evolution section with a comparative approach to genomes and evolution of development, we were able to connect new breakthroughs in these areas and provide a springboard into the diversity section. Major changes in our understanding of phylogenetic relationships among land plants, protists, and fungi along with other major groups, are reflected in the extensive revision of the diversity chapters. Rapid advances in our knowledge of plant defense responses led to a new chapter on this topic.

Writing Style

Students of biology are responsible for an ever-growing volume of information, and that amount of detail is reflected in today's textbooks, which are increasingly becoming encyclopedic references as opposed to teaching texts. But students are more likely to succeed with a text that they enjoy reading, that gives them a sense of the wonderment that inspired their own instructors to study biology. For this reason, we have endeavored to strike a balance; an inviting and accessible writing style with the level of authority and rigor expected of a majors' level text.

To further aid the student, every page or two-page spread in this book functions as a semi-independent learning module, organized under its own heading at the top of the left-hand page, with its own summary at the bottom of the right-hand page. This modular presentation makes the conceptual organization of the chapter clear, greatly enhancing student learning.

Illustrations

This book is set apart form others in that its artists, William Ober, M.D. and Claire Garrison, R.N., are part of the author team. Their respective backgrounds as a practicing physician and pediatric registered nurse, and their experience creating art for highly successful anatomy and physiology, zoology and marine biology textbooks, bring an invaluable contribution to the text. The close collaboration between text and illustration authors results in dynamic, accurate figures that aid student understanding and instructor presentation.

• Combination Figures These pieces combine a photo or micrograph with a line drawing, to make the connection between conceptual figures and what the student may encounter in lab (Figure 5.10, page 88).
• Biochemistry Pathway Icons Found in the discussion of metabolism, these icons help students follow complex processes by highlighting the step currently under discussion (Figure 9.15, page 174).
• Phylogeny Guideposts This icon is presented as each group is introduced, to remind students of relationships among diverse organisms (TA 32.1, page 636).
• Process Boxes These figures include step-by-step descriptions to walk the student through a compact summary of important concepts (Figure 6.18, page 121)

We have also been fortunate in that this collaboration has allowed us to carefully integrate explanatory text into the figures. The end results are uncluttered, easy to follow illustrations that guide a student through a concept. They also benefit the instructor, as figures without distracting captions can be used for presentation while still allowing instructors to tell their own story.

What Sets this Book Apart

Those who have not used or reviewed previous editions will want to know how this book differs from others.

Evolutionary Focus

The treatment of evolution in this book differs from others in a simple but very important way: Evolution is the organizing principle guiding the teaching of each chapter. Instead of leaping from chemistry directly to cell structure as in other books, this book uses the chemistry of the first chapters to examine the origin of life and the evolution of cells; the cell chapters that follow can then be seen in a broader evolutionary context. Similarly, the treatment of animal anatomy and physiology in other books is largely limited to structure and function—this is the organ and this is how it functions. This book examines each animal body system in terms of how it has evolved. Every section of this book, whether it is genetics or plant biology, presents biology from an evolutionary perspective.

Chemistry in a Biological Context

In talking to students over 30 years of teaching freshman biology, a consistent student complaint has been that the introductory biology course begins with a heavy jolt of chemistry. In other books, only after as many as 100 pages of chemistry do students encounter any biology. This is very off-putting for many students, and gets the course off to a rocky start. This book, by contrast, integrates the chemistry of the first section with biological themes. The treatment of macromolecules in Chapter 3 starts with proteins, which can be easily understood without detailed knowledge of carbohydrates. This arrangement has the distinct advantage of starting the student off with material of obvious relevance to biology.

A Modern Approach

Some of the most obvious differences between this book and others can be seen in the second half of the book, that part devoted to coverage of evolution, diversity, plant biology, anatomy and physiology, and ecology.

Evolution.
Our approach to evolutionary biology is unique in two respects. First, we strongly emphasize the role of experiments in studying evolution. Although much of evolutionary biology concerns the study of what happened in the past, that does not mean that experimental approaches are impossible. We emphasize the role that experiments play in studying evolutionary phenomena. More generally, like any detective story, we point out how various approaches must be integrated to fully understand evolutionary diversity.

Second, our book devotes an entire chapter to the evidentiary basis for evolutionary biology. Unlike other aspects of biology, or science in general, the factual basis of evolutionary biology is disputed by some segments of society. Thus, we feel that it is important to clearly present the diversity and depth of evolution that leads almost all biologists to conclude that evolution has occurred. We feel that it is essential for all college biology students—regardless of their own opinions—to understand the scientific basis for this view.

Diversity
Our text has been organized so the diversity section is framed by a discussion of the revolution in taxonomy and phylogenetics (Chapter 25). Complete with vivid examples of dramatic changes in our understanding of relationships among organisms, this chapter can be used alone as an abbreviated approach to diversity or as a foundation for a more comprehensive evolutionary investigation of the diversity of life in the chapters that follow.

The book also differs from other majors' biology textbooks in that its coverage of diversity is more extensive. Consider for example the invertebrates. Other books devote as few as 30 pages to the invertebrates, presenting only the briefest of sketches of what used to be the core of traditional biology courses. This book devotes more than twice as many pages to the invertebrates, followed by a more comprehensive chapter on the vertebrates than is found in other books. Why is this more extensive treatment of diversity important? Even in courses that don't cover diversity in detail, it is important that students be able to uncover for themselves the relations among animal groups.

Plant Biology
The plant biology chapters have undergone extensive revision, and are now organized to lead the student through the plant life cycle. In addition, we have carefully integrated both developmental and genetic perspectives, a fusion not found in other texts. For example, Chapter 36, Vegetative Plant Development, explores root formation in the context of the monopterous mutant of Arabidopsis that fails to make a root. The shift from its developmental role to its functional role as an auxin receptor begins to move students toward a physiological understanding of plant function.

Anatomy and Physiology
Most books devote nearly the same amount of space to anatomy and physiology, about 250 pages. The differences lie primarily in approach, this book having a more evolutionary focus than others, and in its emphasis on fundamentals.

Ecology and Behavior
We take an integrative view to understanding how the environment functions and how organisms interact with it. This section is broken into different chapters, such as behavioral ecology, population ecology, and community ecology, but the topics are carefully integrated. Moreover, we apply this information extensively in Chapters 56 and 57 (The Biosphere and Conservation Biology) to address the environmental issues facing our planet. We believe it is of the utmost importance that students understand the scientific bases to current problems so they can evaluate efforts to solve them.

Changes to the Seventh Edition

The seventh edition of Biology is the result of extensive analysis of the text and evaluation of input from biology instructors who conscientiously reviewed chapters during various stages of this revision. We have utilized the constructive comments provided by these professionals in our continuing efforts to enhance the strengths of the text. Listed first are general changes that have been made to the entire text, which is then followed by specific changes for each part.

End-of-chapter Pedagogy
The end-of-chapter student review has been greatly expanded, offering students a full-page chapter review and three assessment tools: Self Test, multiple choice questions; Test Your Visual Understanding, questions based on a figure from the chapter; and Apply Your Knowledge, critical thinking questions. The assessment doesn't end there, however. These tools are carried over to the web where the student can take an interactive version of the test and receive instructional feedback.

Inquiry Questions
In this edition we have developed Inquiry Questions, which follow the legend in figures presenting graphed data. These questions require the student to think about the information contained in the graph in even greater depth, increasing their understanding of, and facility with, the material.

Answers to both end of chapter questions and Inquiry Questions are found on the Online Learning Center at www.mhhe.com/raven7.

Volumes
We recognize that instructors don't always use the entire text, so we now offer Biology in the following volumes:

Volume 1 Chapters 1–20 Chemistry, Cell and Genetics
Volume 2 Chapters 35–51 Plant Biology and Animal Biology
Volume 3 Chapters 21–34, 52–57 Evolution, Diversity and Ecology

Content Changes by Part

Part I The Origin of Living Things
Part I was revised with the intention of creating a more solid foundation of key concepts in biology, which students can then build on in later chapters. Discussions are now clearer and better supported with illustrations.

New Topics and Revised Treatments
Chapter 1 Properties of life, hierarchical organization Revised; Additional topics in evolution New
Chapter 2 The Nature of Molecules Entire chapter revised
Chapter 3 Figures on chaperons and protein denaturing New; Protein folding, lipids Revised
Chapter 4 Figures on endosymbiosis, Domains/ Kingdoms, phylogenetic tree of life New Bacteria and archaebacteria, microfossils Revised

Part II Biology of the Cell
Randall Phillis assisted in the revision of Part II by directing the authors to concepts that needed additional detail, and by providing suggestions for improving the accuracy and parsimony of the narrative. Concepts that were covered too briefly in previous editions are now supported with more extensive discussion and new illustrations.

New Topics and Revised Treatments
Chapter 6 Membrane microdomains New Osmosis; coupled transport Revised
Chapter 7 Signal amplification, expression of cellular identification Revised
Chapter 8 Redox reactions, ATP functioning Revised
Chapter 9 ATP synthetase New; Electron transport; reducing power; chemiosmosis Revised
Chapter 10 The Calvin cycle Revised
Chapter 11 Cell cycle control New; Chromosome structure Revised

Part III Genetic and Molecular Biology

With the help of Kenneth Mason, Part III was carefully updated to incorporate the most current research. Chapter 13, Patterns of Inheritance, was rewritten for better organization and clearer presentation. Two new chapters provide expanded discussion in fields where our knowledge has grown exponentially.

Chapter 17, "Genomes" integrates plant and animal genomics, functional genomics and proteomics in a chapter that is inquiry driven rather than a discussion of techniques.

Chapter 20, "Cancer Biology and Cell Technology" explores two areas where recent advances in cell and molecular biology have the potential of revolutionizing medicine. The first is cancer, where research into the molecular events leading to cancer is beginning to suggest effective therapies. The second is cell technology, including cloning, embryonic stem cells, and the exciting and controversial proposal of therapeutic cloning.

New Topics and Revised Treatments
Chapter 12 Meiotic prophase Revised
Chapter 13 Patterns of inheritance Entire chapter revised
Chapter 14 Eukaryotic DNA replication Revised
Chapter 15 Eukaryotic transcription New
Chapter 16 The tools of genetic engineering New
Chapter 18 Small RNAs, iRNA, RNA editing New Transcriptional control in prokaryotes Revised
Chapter 19 Vertebrate embryonic axis formation, evolution of homeotic genes New Cell movement; cell induction; embryonic determination; pattern formation Revised

Part IV Evolution

The Evolution section has been revised to bring more experimental data and analysis into the discussions. Because presentation of the experimental data used to derive conclusions and concepts is key to understanding how the concepts arose from the research, you will see that graphs and charts have become more plentiful in these chapters. The evolution of many groups is reassessed in light of new molecular data.

Chapter 24, "Evolution of Genomes and Developmental Mechanisms" is a new comparative genomics chapter that addresses our emerging understanding of the evolution of development, and helps to provide a conceptual framework for the diversity chapters that follow. The chapter was developed in conjunction with Chapter 17, Genomes, to first provide students with an understanding of what we can learn about genomes, and then having learned about evolution, delve into a deeper discussion of how development has evolved to yield novel phenotypes.

New Topics and Revised Treatments
Chapter 21 Measuring fitness, components of fitness, role of selection in maintaining variation New Hardy-Weinberg Revised
Chapter 22 Darwin's finches, industrial melanism New Evidence from developmental biology for evolution Revised
Chapter 23 Plant speciation by chromosomal change, the future of evolution New

Part V Diversity of Life on Earth

The fungi chapter has been moved to the phylogenetically appropriate place in the diversity section following plant diversity. Where appropriate, chapters in the diversity unit have been updated to reflect phylogenetic changes. The thoroughly revised and rewritten Chapter 25, "Systematics and the Phylogenetic Revolution" addresses the current tension between taxonomy and systematics. The chapter can be used alone, to teach the basic concepts of diversity, or can be used as a starting place for a more in-depth study of this area of biology.

New Topics and Revised Treatments
Chapter 25 Phylogenetics and classification Entire chapter revised
Chapter 26 Virus genomes New; Viral diseases and HIV Revised
Chapter 27 Term "eubacteria" replaced with "bacteria," figures of cell structure and clades New
Chapter 28 Phylogenetic approach New; Protist disease in South, Central and North America, relationships between algae and land plants Revised
Chapter 29 Fossil evidence of ancient angiosperm Archaefructacea, evolution of triploid endosperm New Monophyletic relationships between ferns and horsetails Revised
Chapter 30 Fungi Entire chapter revised
Chapter 31 Protostomes and deuterostomes New and expanded Classification Revised
Chapter 32 Protostome phylogeny, rotifers and cycliophora Revised
Chapter 33 Mollusks, annelids, arthropods, and echinoderms combined into one chapter New
Chapter 34 Characteristics and phylogeny illustration, primate evolution New

Part VI Plant Form and Function

The plant biology chapters have been revised so that the traditional discussion of evolutionary influences on plant form and function are brought into a developmental context. Evolution is still presented as the underlying explanation for the character of vascular tissues, seeds, flowers, and fruits, however the developmental processes that produce these organs are now given more emphasis. Two previously combined topics, transport and nutrition, have been split into separate chapters allowing for more in-depth discussion of both topics.

Chapter 39, "Plant Defense Responses" is a new chapter that provides a thorough discussion of secondary compounds and their roles in both plant defense and human applications. Wound responses and R gene mediated responses are explored in depth with an emphasis on signaling pathways.

New Topics and Revised Treatments
Chapter 35 Updated photographs, discussion of genetic regulation of trichomes Revised
Chapter 36 Discussion of signal transduction in germination, comparison of roles of Hox genes in plant and animal development Revised
Chapter 37 Water relations problems, mRNA transport in phloem New
Chapter 38 Newly expanded chapter on plant nutrition. Effects of global change on photosynthesis and balance of plant nutrients, phytoremediation New Nutritional symbioses Revised and expanded
Chapter 40 Signal transduction mediated by light including phot1 New Light responses Revised
Chapter 41 Plant reproduction Entire chapter revised and reorganized

Part VII Animal Form and Function

With the assistance of Randy DiDomenico, many discussions were rewritten for better organization and clarity. Previous chapters on circulation and respiration were combined into one chapter, as were chapters on body organization and locomotion.

New Topics and Revised Treatments
Chapter 42 Combined organization of the animal body and locomotion into one chapter, coordination of organ systems New
Chapter 43 Neural, hormonal and accessory organ regulation New Small intestine discussion reorganized to group all functions together Revised
Chapter 44 Maximizing rate of gas diffusion New Integration of circulation and respiration chapter Revised
Chapter 45 Graded potentials New; Membrane and action potentials, synapses and drug addiction Revised
Chapter 46 Sensory transduction Revised
Chapter 47 The Endocrine System Entire chapter revised
Chapter 48 Immunoglobulins, illustrated table New AIDS Revised
Chapter 49 Discussion of ammonia, urea and uric acid reorganized, nephron Revised
Chapter 50 Sex determination, reptiles and birds Revised Human intercourse Omitted
Chapter 51 Combined discussion of chick and mammalian extraembryonic membranes, neurulation Revised

Part VIII Ecology and Behavior

The ecology and behavior chapters were moved to follow diversity and physiology, where these chapters are more often taught. There is now an even greater emphasis on experimental data and analysis.

New Topics and Revised Treatments
Chapter 52 Animal cognition New; Integration of animal behavior and behavioral ecology chapters Revised
Chapter 53 Introduction to ecology, integration of autoecology and population ecology New Population regulation and limitation, human population growth Revised
Chapter 54 Introduction, definition of community New Parasitism, succession, disturbance Revised
Chapter 55 Geochemical cycles, energy flow, species richness Revised
Chapter 56 Differences between aquatic and terrestrial ecosystems New Integration of biosphere and future of the biosphere chapters, global climate change, El Niño Revised
Chapter 57 Chapter organization, biodiversity hotspots, amphibian extinctions, invasive species New Economic benefits of biodiversity Revised Overview of Changes to BIOLOGY, Seventh Edition
All Cell & Genetics Chapters Extensively Revised

In addition to discussing important advances, many sections have been reworked for improved clarity.

Chapter 17, "Genomes"
This new chapter describes how researchers sequence entire genomes, and how the information is being used.

Chapter 20, "Cancer Biology and Cell Technology"
This new chapter updates progress in understanding cancer, and introduces many new advances in cloning and stem cell technology.

Evolution & Diversity Sections Extensively Revised

New RNA and genomic information is leading to a reassessment of traditional evolutionary phylogenies.

Chapter 24, "Evolution of Genomes and Developmental Mechanisms"
This new chapter explores the wealth of new information on genome sequences, and introduces the new and exciting field of "evo/devo", the evolution of development.

Treatment of Plant Biology Expanded

A total of seven plant chapters provide extensive plant biology coverage with a molecular development point of view. Chapters have been organized to lead the student through the life cycle of a plant.

Chapter 39, "Plant Defense Responses"
This new chapter captures the excitement of this area of biology, which has seen rapid advances and recent breakthroughs in understanding plant defense responses.

Ecology Chapters Updated and Expanded

Up-to-date examples have been integrated into all chapters; note the use of case histories in Chapter 57.

Physiology Chapters Reworked

Discussions of processes like nervous conduction reworked for increased clarity, and related subjects like circulation and respiration treated together.

End-of-Chapter Assessment

Two pages are now devoted to student review and assessment. A full-page chapter summary is followed by multiple choice, illustration-based and application questions.

Illustrations

Many new illustrations clarify difficult concepts; others illustrate tables to aid understanding. Wherever data are presented in graphs, the figure is accompanied by an Inquiry Question to test the student's understanding.

Teaching and Learning Supplements

McGraw-Hill offers various tools and technology products to support Biology. Students can order supplemental study materials by contacting their local bookstore or by calling 800-262-4729. Instructors can obtain teaching aids by calling the Customer Service Department at 800-338-3987, visiting our website at www.mhhe.com/biology, or contacting their local McGraw-Hill sales representative.

For the Instructor:

Digital Content Manager CD-ROM

This multimedia collection of visual resources allows instructors to utilize artwork from the text in multiple formats to create customized classroom presentations, visually based tests and quizzes, dynamic course website content, or attractive printed support material. The digital assets on this cross-platform CD-ROM include:

Art Library Color
enhanced, digital files of all illustrations in the book, plus the same art saved in unlabeled and gray scale versions, can be readily incorporated into lecture presentations, exams, or custom-made classroom materials. Upsized labels make the images appropriate for use in large lecture halls.

TextEdit Art Library
Every line art piece is placed into a PowerPoint presentation that allows the user to revise, move, or delete labels as desired for creation of customized presentations or for testing purposes.

Active Art Library
Active Art consists of art files that have been converted to a format that allows the artwork to be edited inside of PowerPoint. Each piece can be broken down to its core elements, grouped or ungrouped, and edited to create customized illustrations.

Animations Library
Full color presentations involving key process figures in the book have been brought to life via animation. These animations offer flexibility for instructors and were designed to be used in lecture. Instructors can pause, rewind, fast forward, and turn audio off/on to create dynamic lecture presentations.

PowerPoint Lecture Outlines
These ready-made presentations combine art and lecture notes for each of the 57 chapters of the book. The presentations can be used as they are, or can be customized to reflect your preferred lecture topics and organization.

PowerPoint Outlines
The art, photos, and tables for each chapter are inserted into blank PowerPoint presentations to which you can add your own notes.

Photo Library
Like the Art Library, digital files of all photographs from the book are available.

Table Library
Every table that appears in the book is provided in electronic form.

Video Library
Contains digitized video clips that can be inserted into a PowerPoint lecture.

Additional Photo Library
Over 700 photos, not found in Biology, are available for use in creating lecture presentations.

Instructor's Testing and Resource CD-ROM
The cross-platform CD-ROM contains the Instructor's Manual and Test Item File, both available in both Word and PDF formats. The manual contains chapter synopses, objectives, key terms, outlines, instructional strategies and sources for additional visual resources. The Test Bank offers questions that can be used for homework assignments or the preparation of exams. The computerized test bank utilizes Brownstone Diploma testing software, which allows the user to quickly create customized exams. This user-friendly program allows instructors to search questions by topic, format, or difficulty level; edit existing questions or add new ones; and scramble questions and answer keys for multiple versions of the same test.

Transparencies
A set of 1300 transparency overheads includes every piece of line art and table in the text. The images are printed with better visibility and contrast than ever before, and labels are large and bold for clear projection.

Online Learning Center www.mhhe.com/florida/raven7
Instructor resources at this site include access to online laboratories, course-specific current articles, real-time news feeds, course updates and research links.

Course Delivery Systems
With help from our partners, WebCT, Blackboard, TopClass, eCollege, and other course management systems, instructors can take complete control over their course content. These course cartridges also provide online testing and powerful student tracking features. The Biology Online Learning Center is available within all of these platforms.

For the Student:

Online Learning Center www.mhhe.com/florida/raven7
The site includes quizzes for each chapter, interactive activities, and answers to questions from the text. Turn to the inside cover of the text to learn more about the exciting features provided for students through the enhanced Biology Online Learning Center.

Student Study Guide
This student resource contains activities and questions to help reinforce chapter concepts. The guide provides students with tips and strategies for mastering the chapter content, concept outlines, concept maps, key terms and sample quizzes.