Exam 32: An Introduction to Animal Diversity

A researcher is trying to construct a molecular-based phylogeny of the entire animal kingdom. Assuming that none of the following genes is absolutely conserved, which of the following would be the best choice on which to base the phylogeny?

Figure 32.1 shows a chart of the animal kingdom set up as a modified phylogenetic tree. Use the diagram to answer the following questions. -Which group consists of deuterostomes?

Which of the following terms or structures is properly associated only with animals?

The number of legs an insect has, the number of vertebrae in a vertebral column, or the number of joints in a digit (such as a finger)are all strongly influenced by

Table 32.1. Proposed Number of Hox Genes in Various Extant and Extinct Animals -What conclusion is apparent from the data in Table 32.1?

The following questions are based on the description below. A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45 degrees and lie in the grooves between larger, underlying cells (spiral cleavage). -This embryo may potentially develop into a(n)

The following questions are based on the description below. A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45 degrees and lie in the grooves between larger, underlying cells (spiral cleavage). -Phylogenetic trees are best described as

Fossil evidence indicates that the following events occurred in what sequence, from earliest to most recent? 1) Protostomes invade terrestrial environments. 2) Cambrian explosion occurs. 3) Deuterostomes invade terrestrial environments. 4) Vertebrates become top predators in the seas.

The blastopore is a structure that first becomes evident during

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of

Acoelomates are characterized by

The larvae of some insects are merely small versions of the adult, whereas the larvae of other insects look completely different from adults, eat different foods, and may live in different habitats. Which of the following most directly favors the evolution of the latter, more radical, kind of metamorphosis?

Almost all of the major animal body plans seen today appeared in the fossil record over 500 million years ago at the beginning of the

Table 32.1. Proposed Number of Hox Genes in Various Extant and Extinct Animals -Two competing hypotheses to account for the increase in the number of Hox genes from the last common ancestor all bilaterians to the last common ancestor of insects and vertebrates are: (1)a single duplication of the entire 4-gene cluster, followed by the loss of one gene, and (2)3 independent duplications of individual Hox genes. To prefer the first hypothesis on the basis of parsimony requires the assumption that

Figure 32.1 shows a chart of the animal kingdom set up as a modified phylogenetic tree. Use the diagram to answer the following questions. -Which two groups are most clearly represented in the Ediacaran fauna?

What is the main basis for placing the arthropods and nematodes in the Ecdysozoa in one hypothesis of animal phylogeny?

You are trying to identify an organism. It is an animal, but it does not have nerve or muscle tissue. It is neither diploblastic nor triploblastic. It is probably a

The following questions are based on the description below. A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise one hemisphere of the embryo seem to be rotated 45 degrees and lie in the grooves between larger, underlying cells (spiral cleavage). -What does recent evidence from molecular systematics reveal about the relationship between grades and clades?

The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of beta-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If True, this would mean that

Which of the following functions is an advantage of a fluid-filled body cavity?