Biology

Reviewed by Thomas Giardina, Assistant Professor, University of Delaware on 5/21/18

Comprehensiveness rating: 4

This review will focuses specifically on a representative chapter—in this case, Chapter 7: Cellular Respiration. I compare the chapter from Biology 2e to both the first edition Openstax Biology and a traditional introductory text from a major publisher. I selected Cellular Respiration because this is a complex, multi-step concept which is challenging for many students.

In terms of comprehensiveness, Biology 2e is very thorough. The text wastes no words on poetry, and moves through the material with a workmanlike approach. It hits all the major points of cellular respiration, covering some of them in more detail than I would require of an introductory course (the section on glycolysis, for example, walks through each step of the process in the main text, instead of shunting it off into a figure as I have seen in traditional textbooks.) One feature I like is that students can explore these concepts in greater depth by following in-text links to online resources. Especially for multi-step processes like glycolysis and the citric acid cycle, these tools will be useful for visualizing each stage.

I very much appreciated the inclusion of Career Connections and Evolution Connections. These sections make the material more relevant to students, and help them shift focus from the proximate, detail-oriented perspective to the ultimate, ‘big-picture’ perspective. The Scientific Method Connections help to reinforce the process of science, which is always welcome in an introductory class.

One surprisingly omission in this section is the lack of total ATP yield from oxidative phosphorylation. As the text states, the ATP yield from a single molecule of glucose will be variable, so I can appreciate some reluctance to nail down a specific number. However most texts offer a “maximum ATP per glucose” value to frame the possible range, then go on to explain the factors influencing total ATP produced. I think that this omission by Biology 2e makes it difficult to frame how absolutely important oxidative phosphorylation is in terms of energy yield, and also to compare the efficiency of aerobic to anaerobic respiration.

Biology 2e works through cellular respiration diligently and thoroughly, making it very useful as a reference text. However, I would like to see a bit more of the ‘big picture’ ideas of cellular respiration. For example, redox reactions are briefly described, but their value in removing free energy from glucose molecules is given short shrift. What happens to the free energy of that original glucose molecule as it is processed through cellular respiration? Why do organisms need energy at all? Putting these pieces together would help students gain a more unified understanding of cellular respiration as one component of larger biological processes.

Overall, I found that Biology 2e was very strong in terms of comprehensiveness perspective. It was comparable to the similar chapter from a traditional textbook. While I think the traditional text did a better job of framing the big-picture perspective of cellular respiration, the depth offered by Openstax is beyond reproach. This depth is supplemented by online materials which were not offered by the traditional textbook. I found no major changes between Openstax Biology 1e and 2e.

Content Accuracy rating: 5

Overall, this chapter was accurate, with concepts clearly described. I found no problems with the accuracy of major concepts or with the more specific steps of cellular respiration.

I did find a couple of minor errors that are not related to conceptual issues. Both of these could almost be considered ‘typos,’ except for that they risk confusing students. For example, there is one instance in which a figure caption did not match the figure. (Fig 7.4 claims to show a phosphorylation reaction in which the third phosphate of ATP attaches to a protein. However, the image shows the reverse—substrate-level phosphorylation of ATP, in which the third phosphate is attached to ADP from some substrate. This error appears to be due to a change in the figure from the first edition which was not accompanied by a corresponding change to the caption.) In another (pg227, alcohol fermentation), the text claims that it is providing the first chemical reaction of alcohol fermentation below. Instead, both reactions are below, formatted such that they appear on a single line. Again, while this error is very minor, it risks confusing students, especially those not familiar with chemical equations.

Overall, I found this chapter to be of high quality. Although there were some minor figure errors which I did not find in the traditional textbook, there was effectively no difference in accuracy. There were no major differences I observed between 1e and 2e.

Relevance/Longevity rating: 5

I don’t see any problems with relevance/longevity for this chapter, or with the text more broadly. The information provided is up to date and comparable to similar texts. Should our understanding of cellular respiration or fermentation change, the chapter should be easy to update.

Clarity rating: 4

The body of this chapter is readily understandable, with a level of clarity similar to other texts. The figures are far less polished than those found in traditional textbooks, reducing clarity somewhat. However, this is offset by links to online resources which allow students to click through the stages of cellular respiration for themselves. This seems to be representative of the textbook more broadly.

Consistency rating: 4

Overall, this chapter is consistent in its use of terminology and concepts. For example, they use the term “Citric Acid Cycle” instead of the “Krebs Cycle,” and this is conserved throughout the text. (The text does link out to an online resource which invites students to click through the stages of the Krebs Cycle, however the usefulness of this tool far outweighs the confusion of the older term.)

One thing that I would have liked is greater consistency in the figures. For example, figures 7.6-7.8 all label the steps of the reactions taking place, which I found useful. In figure 7.9 (Citric Acid Cycle), this convention is jettisoned. The text describes the reactions in steps, but they are not accompanied by labels on the figure, which I think is a shame. In another example, 7.11 and 7.12 both refer to pH gradients across the mitochondrial membrane. So far as I can tell, pH isn’t referenced in this way anywhere else in the chapter. Although a keen student will immediately connect pH with hydrogen ion concentration, I think it would be more useful and consistent to refer to “hydrogen ion gradient” as it does in the text.

Modularity rating: 5

I found the text to be highly modular. Chapter 7 was broken down into small, manageable sub-sections which could be easily assigned to students.

In fact, I would argue that a strength of digital textbooks is the ability to quickly zip from one section to another with a click. From this perspective, I would have actually preferred if the text was less modular. For example, the structure and function of ATP was discussed only briefly in chapter 7. While this provides a concise orientation to ATP, why not take the opportunity to link to the more detailed description of ATP provided in chapter 6 here?

Organization/Structure/Flow rating: 5

As I would expect, this chapter is organized in a logical, straightforward manner. In traditional fashion, the text begins by introducing the important chemical processes in cellular respiration, then working through the catabolism of a glucose molecule. The placement of the chapter within the larger text makes sense, following a section on the introduction to metabolism, and preceding a section on photosynthesis. Again, I think this structure is typical for an introductory class. This is consistent across the textbook, with the chapters following what I would consider to be a logical flow.

Interface rating: 5

I only viewed the text using a laptop, so I cannot comment on its interface on a smartphone or tablet. That said, I found no problems with the text interface. I personally prefer navigating a physical text to a pdf, however I have observed that students take naturally to the digital format, and stand to benefit from the convenience of carrying their books digitally wherever they go. Should a student wish to purchase a physical copy, they can do so at a very reasonable rate.

Grammatical Errors rating: 5

Overall, grammar in the text is strong. I noticed no grammatical errors in this chapter, though I have noticed a couple minor typos throughout the book. While there are probably a few more grammatical errors than would be typical for a traditional textbook, I have no problems with the grammar of the text.

Cultural Relevance rating: 5

I found nothing in this chapter which could be construed as offensive or insensitive. Naturally, other chapters addresses some scientific concepts which have unfortunately become politicized (evolution and anthropogenic climate change, for example), which may be alienating to some students. The text does not dive into the controversy, merely puts forward the biological information as it should.

I recommend this book highly. While it is not as polished as a traditional text, I feel that the advantages it offers far outweigh the costs. I have personally adopted the Openstax Biology textbook, which I assign to my introductory biology students as a reference text. After one semester of using Openstax, I have received positive feedback from students. In particular, they praise Biology for its convenience, affordability, and succinctness. I am unlikely to switch back to the traditional textbook model, which I feel has become far too costly for my students. Openstax Biology 2e offers a low-cost alternative that meets the needs of an introductory biology class.