McGraw-Hill OnlineMcGraw-Hill Higher EducationLearning Center
Student Center | Instructor Center | Information Center | Home
Table of Contents
About the Authors
Feature Summary
List of Changes
Revision Story
Help Center

Biology, 6/e
Author Dr. George B. Johnson, Washington University
Author Dr. Peter H. Raven, Missouri Botanical Gardens & Washington University
Contributor Dr. Susan Singer, Carleton College
Contributor Dr. Jonathan Losos, Washington University


We enter a new century with this sixth edition of Biology, one that is exploding with excitement in biology. This first year of the new millennium has seen the completion of the Human Genome Project, with the full sequence of the human genome now available for research and exploration. Embryonic stem cells were cloned for the first time in the year 2000, and offer the potential for curing a wide range of ills, from spinal cord injuries to diabetes. Golden rice, a genetically modified crop to which has been added a battery of genes that overcome deficiencies in vitamin A and iron, was planted for the first time in Asian fields. Neurobiologists for the first time caught a glimpse of the molecular basis of learning. Even taxonomy, that bastion of conservative judgments, seems to be undergoing a sea change, with molecular phylogenies forcing the redrawing of many family trees, from angiosperm plants to insects and other arthropods.
There probably has never been a more exciting time to learn biology. Adding together the years, Dr. Raven and I have been teaching biology for more than 70 years, and neither of us can remember any time as fraught with promise as today. We started teaching in the sixties, also exciting times. In those revolutionary years the black box surrounding the gene machine was stripped away, revealing for the first time how DNA achieves the constancy and diversity that are the hallmarks of life. For 40 years researchers have been amplifying that picture, learning in ever-greater detail how life works.
In the last few decades, the pace of biological research has accelerated, as we have learned for the first time how to manipulate genes. In agriculture this has led to waves of controversy, in medicine to advances universally applauded. But no matter how one views genetic engineering, no one questions that it is changing the science of biology in profound ways.
What is important about these changes in biology, what excites us like no past year, is the potential to influence our health, and that of our world. Biology as a science can --indeed, must --be more than simply a trip to the zoo, an investigation of what living things are like and how they work. These things are important parts of biology, of course, the knowledge that provides the core of the science. But it can't stop there. The knowledge of biology that has been gained, especially in the last decade, provides us with a tool of unprecedented power to improve the human condition and lessen human impact on the world we share with life's other creatures.
It is with this sense of a science alive with promise that we set out in the first year of this new century to produce the sixth edition of Biology.

Significant Enhancements to the Sixth Edition
Every revision of a successful text starts with a plan to update areas where advances have occurred. Thus the initial plans for this sixth edition of Biology were to correct any errors detected by its many users, and to incorporate new findings in rapidly advancing areas of research. In publishing terms, this was to have been a "light"; revision. However, that is not what happened. Inspired by the suggestions of reviewers, we found ourselves adding chapters, overhauling the way in which key chapters were organized, adding material and then more material —soon we were knee-deep in a significant revision. Much of the focus of this sixth edition revision was on evolution, ecology, and botany, areas where there was an opportunity for exciting improvement. To revise these chapters, we recruited two young energetic biologists to provide fresh perspective. They brought with them new approaches, fresh ideas, and up-to-date knowledge of their areas of expertise. Indeed, it has been so much fun to work with them that in future editions they will join us as full coauthors of the text.

Ecology and Evolution
Professor Jonathan Losos, our colleague at Washington University, has revised the evolution and ecology sections of the text, bringing more experimental science into our discussions. Presentation of the experimental data used to derive key conclusions and concepts is key to this revision. Our goal is to better aid students to understand how the concepts arose from the research. For this reason, you will see that graphs and charts are more plentiful in these chapters.

Professor Susan Singer of Carleton College has revised the botany chapters. The botany sections have benefited from a new approach where plant development takes center stage. A plant developmental biologist, she has placed the traditional discussions of evolutionary influences on plant form and function into a developmental context. Thus while evolution is still presented as the underlying explanation for the character of vascular tissue, seeds, flowers, and fruits, the developmental processes that produce these organs are now given more prominence. This does not lessen the evolutionary character of the treatment, but rather serves to amplify it. Throughout all the botany chapters, there is an enhanced emphasis on the molecular aspects of plant life. Understanding the molecular underpinnings of plant form and function allows students to more clearly understand the evolutionary changes that have shaped them.

New Chapter: Conservation Biology (Chapter 31)
In the fifth edition, we presented a discussion of conservation biology on the Biology web site, as an "enhancement chapter."; The response to this material was so overwhelming that we have included such a chapter in this edition of our text. In our own classroom teaching we find students to be keenly aware of the problems of dwindling natural resources, and the need to tackle the issue concretely. We feel a chapter focusing on conservation biology will be appreciated by students and useful to professors.

Genomics "Enhancement Chapter";
The rapidly advancing field of genomics is so key to the future of biology that we felt it necessary to discuss it in some way in this sixth edition. Including a chapter in the text seemed rather pointless --so much of what we would cover will have changed after the first year. So we turn again to an "enhancement chapter."; We used enhancement chapters to expand information for the fifth edition of Biology, and as you see from above, after fine-tuning the conservation biology chapter, we now include it in this edition. The enhancement chapter on genomics can be found at This new chapter expands upon the discussion of gene technology to present and explain the advances now being made with genomics. While the chapter discusses the technology involved and the genomes that have been uncoded, it focuses on the significance of this information to biology as a science, and on what it could mean to the future of medicine, agriculture, and many other fields.

Real People Doing Real Science
We have added an inquiry-based learning experience at the beginning of every Part that walks a student through the process of scientific inquiry by examining a particular experiment. We have titled this feature "Real People Doing Real Science."; After briefly reviewing the significance of the experimental question being addressed, we take the student through the actual experiment, discussing experimental design in depth, and then briefly describe the results and conclusion. This is but the first part of the learning experience. The student is then directed to the Biology sixth edition web site for an in-depth examination of the experiment. There a student can read the actual published research paper, allowing students to become more familiar with the primary literature. Then the student can carry out a "Virtual Experiment"; where he or she is able to manipulate the parameters of the experiment and obtain data for analysis. We provide on-line questions and discussions to help the student better understand the thought process behind the experiment.

A Thorough Revision

In addition to the extensive revisions of the ecology, evolution, and botany sections of the text, and new chapters on genomics and conservation biology, we have thoroughly revised the rest of the text as well. Many chapters now sport radically different organizations, benefiting from extensive reviewer input. Pedagogy has been improved as well. We have included phylogenetic guideposts throughout the discussions of diversity to clarify for the student where each group fits in the tree of life. (You will find these guideposts in chapters 35, 36, 37, and 44 –48.) <a onClick="'/olcweb/cgi/pluginpop.cgi?it=jpg::::/sites/dl/free/0073031208/27096/pic02.jpg','popWin', 'width=NaN,height=NaN,resizable,scrollbars');" href="#"><img valign="absmiddle" height="16" width="16" border="0" src="/olcweb/styles/shared/linkicons/image.gif"> (8.0K)</a>


The Chemical Building Blocks of Life (Chapter 3)
The organization of this chapter has been turned on its head, presenting lipids before carbohydrates. This gives a greatly improved sense of the relative biological importance of these macromolecules, and actually makes the material easier to learn.

The Origin and Early History of Life (Chapter 4)
The discussion of ideas about the origin of life is now much more open-ended, stressing competing hypotheses and the key role of assumptions for which there is little data.

Photosynthesis (Chapter 10)
The internal organization of this chapter has been reworked to make it easier for students to understand how the many concepts covered in this chapter relate to one another.

Patterns of Inheritance (Chapter 13)
This chapter has been reorganized to incorporate the discussion of human genetics earlier in the chapter and then to use human examples as a means of explaining Mendelian principles.

Cellular Mechanisms of Development (Chapter 17)
We have moved the discussion of cellular development up earlier in the text, immediately following the discussion of gene expression, to reinforce key molecular concepts.

Altering the Genetic Message (Chapter 18)
Many recent advances in cancer research are highlighted, with greater emphasis on genes governing metastasis and angiogenesis.

Gene Technology (Chapter 19)
New topics such as biochips and transgenic rice have been included and rapidly advancing areas such as stem cells and ethics and regulations have been updated.

The Evidence for Evolution (Chapter 21)
We have expanded this chapter to include a complete discussion of the evolution of the horse, and have expanded the discussion of artificial selection as a means of showing the power of selection on the evolution of species.

Population Ecology (Chapter 24)
We have added and expanded the discussions of population distributions, ranges, dispersal mechanisms and human effects in examples replete with actual data.

Animal Behavior (Chapter 26) and Behavioral Ecology (Chapter 27)
We have amplified these two chapters, moving them to the ecology section, a more logical place to teach these topics.

Dynamics of Ecosystems (Chapter 28)
We have greatly expanded discussions of interactions among trophic levels and the controversial matter of how species richness influences community stability.

The Biosphere (Chapter 29)
We have expanded the discussion of evolutionary responses to environmental variation.

Evolutionary History of Plants (Chapter 37)
We now include a discussion of the "Deep Green Project"; that demonstrated the green algal origin of all plants.

The Plant Body (Chapter 38)
We included a discussion of the genes involved in development of stomata, trichomes, root tissues and leaves.

How Plants Grow in Response to Their Environment (Chapter 41)
This chapter was extensively reworked and many new topics were added and expanded such as acid growth hypothesis of auxin actions, plant defense responses, cytokinin involvement in organ regeneration and crown gall tumors, brassinosteroids and oligosaccharins, transgenic tomatoes, initiating flowering, and circadian clocks.

The Noncoelomate Animals (Chapter 44)
This chapter now includes a molecular reevaluation of the evolution of the metazoan body plan.

Arthropods (Chapter 46)
New molecular data calls into question traditional classification of arthropods based on external characteristics.

Locomotion (Chapter 50)
We have added a discussion of modes of locomotion that ties together the concepts presented in the chapter.

Circulation (Chapter 52)
We have added a section on heart disease, explaining that heart disease is preventable and begins with establishing a heart-healthy lifestyle early.

Sensory Systems (Chapter 55)
We have broadened the coverage in this chapter to include more examples of nonmammalian sensory systems.

The Immune System (Chapter 57)
This chapter has been completely reorganized to improve clarity and understanding. The presentation of topics now more logically follows the process of the immune response in the body.