The emphasis on the scientific process has been strengthened. The first chapter has an improved description of the scientific process using a more appealing and modern example. The end matter of each chapter contains Thinking Scientifically questions and these give students an opportunity to participate in the scientific process and learn to think critically. The Scientific Focus readings are more varied this edition. These readings discuss recent biological research in the area under discussion.

An increased use of icons occurs in the cell, ecology, diversity, and systems chapters. An icon of the cell reminds students of the location of an organelle. The cellular respiration icon shows where a particular pathway or cycle is occurring in the cell. Phylogenetic tree icons remind students of the evolutionary relationship among groups of organisms.

The use of color consistency has been increased. Each type molecule (fat, protein, nucleic acids) is colored the same not just in the chemistry chapters but also throughout the book. Each type organelles is colored the same not just in the cell chapter but also throughout the book.

Many illustrations have been revised to improve their student appeal and educational design. The addition of icons helps students relate the part to the whole and the addition of micrographs relates the art to an actual structure. Illustrations throughout the book have tastefully and skillfully improved through the efforts of a designer.

All heads have been shortened and simplified in this edition to better reflect the content of the section that follows. For example, the head "Comparing Digestive Tracts" is now simply "Digestive Tracts" and the head "Feeding is Continuous or Discontinuous" has become "Continuous versus Discontinuous Feeders."

Modernized classification system now recognizes the three domains of life: Archaea, Bacteria, and Eukarya. The kingdoms Protista, Fungi, Plants, and Animals are in the domain Eukarya. The relationship between the five-kingdom system of classification system and the new system is discussed in the text.

A bioethical issue has been added to the end of most  chapters. These cover a wide range of issues that require thoughtful consideration by society at this time. The issues end with appropriate questions to help students center their thoughts and opinions. The myriad of issues considered include genetic disease testing, human cloning, AIDS vaccine trials, animal rights, responsibility for one's health, and fetal research.

Chapter 9 Cellular Reproduction and the Cell Cycle. This chapter is reorganized and ends with a discussion of the relationship between the cell cycle and cancer.

Chapter 27 Conservation Biology. This chapter discusses current biodiversity crises including why we should care, the root causes, and how to preserve species and prevent extinctions.

Chapter 30 Protists. This chapter was thoroughly updated to better reflect modern concepts regarding protist diversity.

Chapter 37 Nutrition and Transport in Plants. This chapter begins with a new section that includes a discussion of soil formation and its nutritional functions. New figures support an improved discussion of xylem and phloem transport. The majority of illustrations in this chapter are new and most of the others have been revised.

Chapter 46 Neurons and Nervous Systems. The chapter has been reorganized and rewritten for better flow. The more thorough discussion of the central nervous system includes a new section on learning and memory.

Chapter 49 Hormones and Endocrine Systems. This chapter better emphasizes the role of hormones in homeostasis and the effects of imbalance on the human phenotype.

1. Section 1.3 How Living Things are Classified. The classification system has been modernized - a more inclusive category, domain, has been added. Fig. 1.6*
2. Section 1.4 The Process of Science. Expanded discussion of the scientific process using a more appealing and modern example. Fig. 1.7
3. Chapter 3. New emphasis on the concept that the shape of a molecule influences its role in cells. Fig. 3.9, 3.10, 3.18, 3.19
4. Chapter 8. Four phases of complete glucose breakdown. Each phase is color-coded and the figure when reduced serves as an icon for other illustrations in the chapter. The illustration for each phase is colored to match the color in the icon. Fig. 8.2 and following.
5. Section 9.3. The revision of this chapter emphasizes the connection between cell cycle control and the development of cancer. The p53 gene is involved in control of the cell cycle and also in turning on apoptosis when DNA is damaged and cannot be repaired. Fig. 9.9
6. Table 13A is a new table that lists and describes the genetic disorders discussed in the chapter. It also gives their frequency and the genetic testing available for that condition.
7. Section 14.1 The Genetic Material. Improved discussion and illustrations of Griffith's transformation experiment and the Hershey and Chase DNA versus protein experiment. Figs. 14.1 and 14.3
8. Section 16.3 Genetic Mutations. A general discussion of mutagens leads to different types of mutations and the possible effects of nonfunctional proteins. Carcinogens are mutagens that affect the activity of oncogenes and tumor-suppressor genes. Fig. 16.14-16.17
9. Chapter 17 Reading: Organs for Transplant. Includes a discussion of xenotransplantation and bioartificial organs through tissue engineering as alternatives to using humans organs for transplant.
10. Section 17.3 The Human Genome Project. Expanded coverage of the purpose and benefits of this project.
11. Section 17.4 Gene Therapy. Expanded coverage of gene therapy methodology and the modern use of gene therapy to treat cancer.
12. Chapter 18, Science Focus: The Pace of Evolution. The discussion of punctuated equilibrium is now more appropriately placed in the section regarding fossil evidence for evolution. Fig. 18C
13. Section 21.3 Evolution of Humans. This section was updated to reflect the very latest approach regarding human evolution. Fig. 21.9
14. Section 25.2 Biogeochemical cycles. This section now includes how altered transfer rates in biogeochemical cycles lead to pollution. Figs. 25.13, 25.14, 25.16, and 25A
15. Chapter 26 Ecology Focus: El Nino-Southern Oscillation Explanation of the El Nino phenomenon and its effects on the weather.
16. Section 28.3 Systematics Today. This section was rewritten to better describe the cladistics school of systematics. Figs. 28.11-28.13
17. Section 29.4 The Archaea. An expanded discussion of the archaea, one the Domains of life. Figure 29.11
18. Section 35.3 Vertebrates. A new emphasis on the diversity of vertebrates has been expanded and is supported by the addition of several new photos. Fig. 35.6, 35.8, 35.10, 35.13, 35.15, 35.18
19. Section 36.5 Organization Stems. The contrast between herbaceous stems has been improved and the development of a woody stem has been clarified. Figs. 36.15 and 36.16.
20. Section 37.3 Transport Mechanisms in Plants. An improved discussion of xylem and phloem transport is supported by new figures including 37.11 and 37.12.
21. Section 39.4 Asexual Reproduction in Plants. Includes an expanded and updated coverage of plant genetics and a reading concerning the model plant Arabidopsis thaliana.
22. Chapter 42. Health Focus: AIDS. An updated and expanded discussion of AIDS includes the transmission, phases, treatment, and prevention of AIDS. Fig. 42.B
23. Section 42.5 Immunity Side Effects ends with an improved discussion of the allergic response. Fig. 42.13
24. Section 44.3 Respiration and Health. The revised section includes discussions of a greater number of upper and lower respiratory tract infections and disorders. Fig. 44.10
25. Section 47.3 Sense of Hearing and Balance. This section was reorganized and rewritten so that the process of hearing now immediately follows the anatomy of the ear. The discussion of balance follows. Fig. 47.10 and 47.11
26. In section 51.2, the discussion of model organisms (round worm and fruit fly) is new. The study of these organisms has increased our understanding of developmental genetics including the role of homeotic genes. Figs 51.9 and 51.10

Illustrations have been improved throughout and many have a new vibrant appearance. New illustrations of particular interest are

1.7 An experiment in the field. A new figure that accompanies the improved description of the scientific process.

2.9 Water as a transport medium in trees. Explanatory statements were added to better convey the concept.

3.10 Phospholipid structure and shape. Figure now shows how the shape of a phospholipid is appropriate to the role it plays in the plasma membrane.

4.9 Cell fractionation. A new figure that shows the role of cell fractionation in determining the function of cell parts.

6.8 Feedback inhibition. This mechanism for controlling an enzymatic pathway is explained by a sequence of drawings rather than with one drawing as in the previous edition.

7.2 Chloroplast structure and function. Figure is a flow diagram from the plant to the leaf, individual cell, chloroplast, and finally the thylakoids. The figure is improved by the addition of a cell micrograph.

7.9 Carbon dioxide fixation. This illustration better conveys the differences in structure and function between C3, C4, and CAM plants.

8.2 Four phases of complete glucose breakdown. Each phase is color-coded and the figure when reduced serves as an icon for other illustrations in the chapter. The illustration for each phase is colored to match the color in the icon.

9.9 Functions of p53. The figure emphasizes this gene's function in triggering apoptosis when DNA is damaged and cannot be repaired.

10.5 Independent assortment. Helps students visualize that variety of chromosomal combinations possible in daughter cells following meiosis.

11.3 Monohybrid cross and all illustrations of crosses in chapter 11. New design allows students to center in on the cross and not get distracted by the use of multicolors.

14.1 and 14.3 Griffith's transformation experiment and the Hershey and Chase genetic material experiment . These improved illustrations allow students to better follow the steps of the experiments and how rationale of the conclusions.

15.4 Overview of gene expression. Provides a foundation for an understanding of the stages in gene expression.

16.1 and 16.2 The trp operon and the lac operon. New improved illustrations are easier to follow and understand.

17.9 Genetically engineered animals. A flow chart that illustrates the methodology for genetic engineering a farm animal followed by cloning of this animal.

18.14 Evolutionary history of Equus. The discussion of Equus evolution is now supported by an illustration.

18C Phyletic gradualism versus punctuated equilibrium. New illustration shows the contrast between phyletic gradualism versus punctuated equilibrium in a more appealing and simplified manner.

19.6 - 19.8 Three modes of natural selection. Revised art more clearly shows the difference between directional, stabilizing, and disruptive selection.

20.6 Fossils. A pictorial display of different types of fossils throughout the history of life on earth. This illustration accompanies Table 20.1 The Geological Time Scale.

21.3 Human evolution. A new and modern representation of fossil hominids and humans.

23.16 Resource consumption for MDCs and LDCs. Diagram contrast population size versus resource consumption.

25A Ozone depletion. Pictorial explanation of how chlorine causes ozone depletion.

26A La Nina versus El Nino. Explain weather patterns and their effects associated with La Nina and El Nino.

Chapter 27 All illustrations are new in the Conservation chapter which is also new.

28.7 Ancestral angiosperm. Newly found fossil which is thought to be the earliest angiosperm to be discovered

28.11, 28.12, 28.13 Cladistics. Illustrations that accompany the improved discussion of cladistics. They assist student understanding of the three schools of systematics.

29.11 Archaea habitat and structure. Pictorial representation of three different types of archaea and where they live.

30.2 Protist diversity. Pictorial representation of various protists shows how diverse the members of this kingdom are.

31.3 Black bread mold Rhizopus solonifer. Improved life cycle clarifies the life cycle stages of this organism.

33.2 Phylogenetic tree of the animal kingdom. A new tree which better reflects evolutionary principles and the modern approach to animal evolution.

34.3 - 34.7 and 34.11 The protosomes. These illustrations were improved by the addition of photos to better reflect the diversity of animal groups.

34.9 Arthropod skeleton and eye. An external skeleton and a compound eye are significant characteristics of arthropods.

35.4 Phylogenetic tree of the chordates. A new tree which better reflects evolutionary principles and the modern approach to animal evolution.

35.6, 35.8, 35.10, 35.13, 35.15, 35.18 Vertebrate diversity. These illustrations were improved by the addition of photos to better reflect the diversity of animal groups.

36.15 and 36.16 Woody stems. Reorganization of these figures from the previous edition better supports an improved discussion of the development of a woody stem.

36.18 Leaf Structure. This illustration has been expanded by the addition of an icon and blow-ups of a plant cell and a stomate.

37.11 and 37.12 Xylem and phloem transport in plants. A much improved representation of the cohesion-tension model and the pressure-flow model.

39.3 Life cycle of a flowering plant. Figure has been redesigned so that 39.a and b use the same call outs to better assist student understanding.

39.11 Tissue culture. Supports an improved discussion of plant genetics.

42.8 Clonal section theory as it applies to T cells. This new illustration incorporates the role of apoptosis in suppression of the immune response.

44.5 Respiratory system in birds. More thorough representation of the one-way system of air flow through the lungs in birds.

45.7 Nephron anatomy. An updated representation of the nephron is enhanced by the addition of micrographs.

45.9 Steps in urine formation. A revision of 45.9 from the previous edition more clearly delineates the three steps in urine formation.

46.4 and 46.5 Transmission of the nerve impulse along a fiber and at the synapse. Improved illustrations that will assist student understanding.

47.11 Sensory receptors for balance. Dynamic and static equilibrium are better contrasted in this new illustration.

48.13 Contraction of a muscle. A more dynamic and thorough overview of muscle fiber contraction than figure 48.12 in the previous edition.

49.9, 49.11 Regulation of blood calcium level and regulation of blood glucose level respectively. These diagrams more accurately represent homeostatic mechanisms for regulating blood levels of substances.