Campbell Biology In Focus
2nd Edition
ISBN: 9780134203072
Author: Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Jane B. Reece
Publisher: PEARSON
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Textbook Question
Chapter 27.3, Problem 2CC
WHAT IF? Would it be accurate to describe the Cambrian explosion as consisting of three “explosions,” not one? Explain your reasoning and summarize the major steps in animal evolution shown in Figure 27.10.
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WRITE ABOUT A THEME: Organization You have seenmany examples of how form fits function at all levels of thebiological hierarchy. However, we can imagine forms thatwould function better than some forms actually found innature. For example, if the wings of a bird were not formedfrom its forelimbs, such a hypothetical bird could fly yet alsohold objects with its forelimbs. In a short essay (100–150words), use the concept of “evolution as tinkering” to explainwhy there are limits to the functionality of forms in nature.
You have now studied three different types of anatomical structures.
Homologous structures show individual variations on a common anatomical theme. These
are seen in organisms that are closely related.
1. Give an example of a homologous structure from this activity:
Analogous structures have very different anatomies but similar functions. These are seen in
organismsthat are not necessarily closely related but live in similar environments and have
similar adaptations.
2. Give an example of an analogous structure from this activity:
Vestigial structures are anatomical remnants that were important in the organism's ancestors
but are nolonger used in the same way.
3. Give an example of a vestigial structure from this activity:
\. Read some papers (find them using any of several literature-search engines that your instructor can suggest) that make different estimates of the timing of either the origin of bilaterian animal phyla or the orders of mammals. How different are the estimates based on molecular clock evidence versus paleontological evidence? What might account for these differences, and how might they be resolved?
Chapter 27 Solutions
Campbell Biology In Focus
Ch. 27.1 - Prob. 1CCCh. 27.1 - Prob. 2CCCh. 27.2 - What is the Cambrian explosion? Why is it...Ch. 27.2 - Prob. 2CCCh. 27.3 - Prob. 1CCCh. 27.3 - WHAT IF? Would it be accurate to describe the...Ch. 27.4 - Prob. 1CCCh. 27.4 - Describe two key adaptations of aquatic...Ch. 27.4 - MAKE CONNECTIONS The radiation of bilaterians in...Ch. 27.5 - Describe two adaptations that have enabled insects...
Ch. 27.5 - MAKE CONNECTIONS Compare and contrast how the...Ch. 27.6 - Describe three key amniote adaptations for life on...Ch. 27.6 - Prob. 2CCCh. 27.6 - WHAT IF? Which came first, the chicken or the egg?...Ch. 27.7 - Describe how ocean communities changed in the...Ch. 27.7 - Prob. 2CCCh. 27.7 - Prob. 3CCCh. 27 - Prob. 1TYUCh. 27 - Fossil steroid and molecular clock evidence...Ch. 27 - Which of the following was probably the least...Ch. 27 - Prob. 4TYUCh. 27 - Prob. 5TYUCh. 27 - Prob. 6TYUCh. 27 - Prob. 7TYUCh. 27 - FOCUS ON EVOLUTION In Figure 27.29, circle the...Ch. 27 - FOCUS ON ORGANIZATION Early tetrapods had a...Ch. 27 - SYNTHESIZE YOUR KNOWLEDGE Collectively, do these...
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- Please do fast How old are the first recognizable mammals relative to the K/T boundary layer (i.e., extinction of the dinosaurs), and from what reptilian lineage did they evolve? Is this lineage the same reptilian lineage that gave rise to birds? How are these lineages distinguished? Hold old are the first fossil birds? What other plant/animal lineages first became widespread in the Tertiary that were less common in the Cretaceous?..arrow_forwardThe forelimbs of the organisms in Figure 1 are examples of what type of structures? What do these structures indicate about the evolution of the three organisms? What would be an example of a structure analogous to the last structure? How does the anatomy of the forelimbs show an evolutionary pattern?arrow_forwardTest Your Understanding Know and Comprehend 4. The presence of homologous structures in two different groups of organisms suggests that (a) the organisms evolved from a common ancestor (b) convergent evolution has occurred (c) they belong to a polyphyletic group (d) homoplasy has occurred (e) independently acquired characters may evolve when organisms inhabit similar environmentsarrow_forward
- Test Your Understanding Know and Comprehend 3. Each branching point in a cladogram (a) is called a root (b) represents a clade (c) represents the divergence of two or more groups from a common ancestor (d) represents horizontal gene transfer (e) marks the divergence of two kingdomsarrow_forwardTest Your Understanding 7.Which of the following is true of mammals? (a) they evolved from saurischian dinosaurs (b) they are exotherms (c) they have hair and three middle ear bones (d) mammalian embryos do not have an amnion (e) they all bear their young alive (do not lay eggs).arrow_forward1. Concept Check The similarity in bone structure and arrangement between cats and bats suggests that Humerus Radius Ulna Carpals Metacarpals Phalanges Human Cat Whale Bat a) bats originated from bird-like ancestors. b) bats originated from four-legged ancestors, such as cats. c) modern bats fly much faster than ancient bat species. © 2018 Pearson Education, Inc. 2. Concept Check Darwin proposed the theory of natural selection as the mechanism of evolution based on three observations about nature. Which of the following were part of Darwin's observations? a) Populations have the potential to produce more individuals than the environment can support. b) Individuals in some populations have varied characteristics. Variation in individuals appears to be inherited. d) all of the above © 2018 Pearson Education, Inc.arrow_forward
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