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from The Textbook Letter, September-October 1997

Reviewing a high-school book in biology

Biology: Visualizing Life
1998. 895 pages. ISBN of the student's edition: 0-03-016723-X.
Holt, Rinehart and Winston, Inc.,
1120 South Capital of Texas Highway, Austin, Texas 78746.
(This company is a division of Harcourt Brace & Company,
which is a part of Harcourt General Inc.)

This Is a Superior Textbook,
but Its "Lab Program" Fails

Lawrence Davis

The first version of Biology: Visualizing Life appeared some four years ago, with a 1994 copyright date and a strikingly fresh approach to high-school biology. Now Holt has issued a second version with significant improvements.

[Editor's note: Two reviews of the 1994 version ran in TTL for May-June 1994, with these headlines: "This Biology Book Is One of the Best" and "Right for Some Students, but Not Right for Others."]

The new book, like its predecessor, is divided into six units: "Study of Life," "Continuity of Life," "The Environment," "Diversity of Life," "Animal Kingdom" and "Human Life." New chapters on "Cell Reproduction" and "Animal Behavior" have been added to the second unit, while a chapter on "Drugs and the Nervous System" has disappeared from the sixth unit; otherwise, the sequence of chapters has not been disturbed.

Within the chapters themselves, much of the graphic work and many of the illustrations remain essentially the same, and much of the text has been retained verbatim. However, some sections have been rearranged, some paragraphs have been revised or replaced to make room for new material, and the end-of-chapter "Review" pages have been overhauled.

In my review of the 1994 version, I was critical of the "Review" sections because they depended almost entirely on multiple-choice questions and other items that didn't demand much thought. Now, remarkably, all of those are gone, and the new "Review" sections have questions that require higher-level thinking. This is a salutary saltation in textbook evolution. An experienced teacher can make good use of the new "Review" pages for inducing students to get involved with the text.

One conspicuous change in the book's scientific content deals with classification. The 1994 version divided the living world into five kingdoms, but the new version recognizes six: the Archaebacteria, Eubacteria, Protista, Fungi, Plantae and Animalia. This scheme is evidently becoming fashionable among the writers of high-school biology texts, and there are good reasons for placing the archaebacteria in a kingdom of their own.

We should remember, however, that the six-kingdom system perpetuates one of the major defects of the five-kingdom system, because it preserves the kingdom Protista. This so-called kingdom isn't a natural group -- i.e., it isn't monophyletic. It is a polyphyletic hash comprising all the eukaryotes that don't qualify as fungi, plants or animals.

Holt's writers have some awareness of this, and they even refer to the Protista as "a catchall kingdom" (page 325). They do not explicate this in terms of monophyly and polyphyly, however, nor do they demonstrate that they really have integrated the six-kingdom approach into their thinking. On page 325 they say that archaebacteria "gave rise to eukaryotes"; then on page 333, where they combine a picture of Escherichia coli with some statements about "Evolutionary Relationships," they create the implication that the progenitors of eukaryotes were eubacteria. The endosymbiont hypothesis for the origin of eukaryotes appears only on page 54 and is linked only to the origins of the eukaryotes' chloroplasts and mitochondria. There is no recognition of the broad proposition that eukaryotes per se had a symbiotic origin.

In chapter 4, "The Living Cell," there has been a big improvement in the discussion of diffusion as a mass-transfer mechanism. The 1994 version had traditional, erroneous pictures that showed droplets of ink sinking in a beaker of water, thus confusing diffusion with convection. The new version has pictures of real diffusion -- the diffusion of a dye through a mass of gelatin. This is the first high-school biology textbook in which I have seen a valid demonstration of diffusion, though Steven Vogel has been telling us, for years, how to do it. See, for instance, his article in The American Biology Teacher, October 1994.

Just as the 1994 version did, the new Visualizing Life offers a strong, forthright treatment of evolutionary biology. Evolution continues to function as a theme that runs through the whole book, though some of the individual passages that deal with evolution have been altered. For example, the hoary tale about horses' toes has been replaced by material derived from recent studies of the evolution of whales, and the section about evolutionary mechanisms now concludes by emphasizing an important point: "Note that the disagreement about punctuated equilibria is a debate about the rate and regularity of evolution, not about whether evolution occurs." Biology teachers will be pleased. Creationists will not, since one of their favorite falsehoods is the claim that scientists, unable to agree about the details, have renounced the whole idea of evolution. Creationists will find many other items to dislike, too, such as this "Review" question in chapter 12: "The DNA nucleotide sequences of chimpanzees and humans differ by only 1.6 percent. The DNA sequences of gorillas differ from those of humans by about 2.3 percent. What do these differences reveal about the evolutionary relationship among these primates?"

In the "Human Life" unit, the passage about the eye has been strengthened, and it now gives a fairly accurate description of how photons travel to the retina, but the accompanying illustration is the same one that appeared in the 1994 book. The illustration doesn't agree with the text, and it is wildly wrong when it shows that light rays converge in front of the eye and then diverge behind the cornea. The writers and illustrators are still working at cross-purposes -- here and in some other places too. Where the 1994 version misrepresented a protein's alpha helix as a wavy ribbon, the new book shows a protein as a mess of colored balls that look like jellybeans being spilled from a bowl; it's colorful but it has zero meaning. (Any protein chemist could have helped Holt's illustrator generate a legitimate, informative illustration by using one of the many computer-graphics programs that draw protein structures.) The "rice" plant shown on page 413 is unlike any that I ever have seen, even in China. The "garden pea" flower on page 117 has stamens and pistils that resemble those of a Christmas cactus, not a pea. (A pea flower has ten stamens and one capitate pistil, as may be seen in any old botany book.) Why has such shoddy work been allowed to persist in a textbook whose illustrations are generally competent?

Apart from the aforementioned addition of two new chapters, the biggest change in the book's organization involves its supply of activities. In the first version of Visualizing Life, each chapter finished with an activity called an "Investigation." In the new version, all the activities appear in a "Lab Program" at the back of the book. I suspect that the rationale is to provide something that resembles a lab manual. The "Program" fills some 80 pages, and each activity is labeled as an "Exploration" or an "Investigation" or an "Interactive Exploration." An "Exploration" is a conventional exercise in which the student is supposed to learn a lab technique by following step-by-step instructions. An "Investigation" requires the student to devise and apply a procedure while pretending to be an employee of a consulting firm. In an "Interactive Exploration," the student explores a CD-ROM, summons visual displays, and (usually) generates or interprets some graphs.

All told, there are 34 activities. All told, they fail to do a satisfactory job of connecting the student to biological reality. A model stored on a CD-ROM may be a useful supplement to the text, but manipulating such a model is not lab work and is not a substitute for handling and observing organisms. In the 1994 version of Visualizing Life, the "Investigation" pages presented activities such as dissecting a chicken wing, dissecting a flower, growing bean plants, and manipulating pill bugs -- but these have now been abandoned. It is a real loss when young students, instead of dealing with organisms, devote their so-called lab time to drawing cladograms, making paper chromatids, or "modeling" things that they never have seen in the real world.

Still, some of the activities in the newer book are commendable for their sophistication: They pose problems and then they ask the student to develop solutions, given a list of some available materials. This approach should help students to get students involved in thinking.

The first version of Visualizing Life was good, and this second version, overall, is significantly better. Perhaps the third version will be a truly great biology text.


Lawrence Davis is a professor in the Department of Biochemistry at Kansas State University (Manhattan, Kansas). He specializes in the biology and chemistry of nitrogen fixation.

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