Exam 32: An Overview of Animal Diversity

The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups-Lophotrochozoa and Ecdysozoa. What does this finding suggest?

Among protostomes, which morphological trait has shown the most variation?

Use the table to answer the question. Proposed Number of Hox Genes in Various Extant and Extinct Animals What conclusion can best be drawn from the data in the table?

The common ancestor of the protostomes had a coelom. What does this suggest?

The fact that choanoflagellates and collar cells of sponges resemble each other supports the inference that ________.

Why might researchers choose to use molecular data (such as ribosomal RNA sequences) rather than morphological data to study the evolutionary history of animals?

What is the probable sequence in which the following animal clades originated, from earliest to most recent?

One hypothesis suggests that the Cambrian explosion was caused by the rise of predator-prey relationships. This hypothesis is best supported by an increased incidence of which of the following fossil traces?

Use the table to answer the following question. As you are on the way to Tahiti for a vacation, your plane crash lands on a previously undiscovered island. You soon find that the island is teeming with unfamiliar organisms, and you, as a student of biology, decide to survey them (with the aid of the Insta-Lab Portable Laboratory you brought along in your suitcase). You select four organisms and observe them in detail, making the notations found in the figure. In which of the organisms listed would you search for photosynthetic genes?

Placing sponges as the basal metazoans on the basis of lack of tissues implies which of the following?

A student encounters an animal embryo at the eight-cell stage. The four smaller cells that comprise 1 hemisphere of the embryo seem to be rotated 45° and to lie in the grooves between larger, underlying cells. This embryo may potentially develop into a(n) ________.

Arthropods invaded land about 100 million years before vertebrates. This fact most clearly implies that ________.

The primary difference between a coelom and a pseudocoelom is ________.

Use the figure to answer the question. Which of the following statements is supported by the phylogeny in the figure?

Which of the following is (are) unique to animals?

Use the information to answer the question. Trichoplax adhaerens is the only living species in the phylum Placozoa. Individuals are about 1 mm wide and only 27 µm high, are irregularly shaped, and consist of a total of about 2,000 cells, which are diploid (2n = 12). There are four types of cells, none of which are nerve or muscle cells, and none of which have cell walls. Individual animals move using cilia, and any "edge" can lead. T. adhaerens feeds on marine microbes, mostly unicellular green algae, by crawling atop the algae and trapping it between its ventral surface and the substrate. Enzymes are then secreted onto the algae, and the resulting nutrients are absorbed. T. adhaerens sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage. Which of the following T. adhaerens traits is different from all other known animals?

Use the figure to answer the question. Which of the following pairs of animals show that animals with widely different adult features can be each other's closest relatives?

When a scientist describes the "body plan" of a phylum, he or she is implying that ________.

Which tissue type or organ is not correctly matched with its germ layer tissue?

Use the information to answer the question. Nudibranchs, a type of predatory sea slug, can have various protuberances (that is, extensions) on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear many chemoreceptors. Dorsal plumules, usually located posteriorly, perform respiratory gas exchange. Cerata usually cover much of the dorsal surface and contain nematocysts at their tips. If nudibranch rhinophores are located at the anterior ends of these sea slugs, then they contribute to the sea slugs' ________.