Exam 32: An Overview of Animal Diversity

At one time, sponges were lumped into one phylum. Then, they were separated into several different phyla. Now, they are considered one phylum again. These changes indicate which of the following?

Which of these statements, if accurate, would support the claim that the ancestral cnidarians had bilateral symmetry?

The evolution of animal species has been prolific (current estimates of species numbers reach into the tens of millions). Much of this diversity is a result of the evolution of novel ways to ________.

As you are on the way to Tahiti for a vacation, your aeroplane 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 collagen?

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?

What do all deuterostomes have in common?

Which of the following statements concerning animal taxonomy is accurate?

Which of the following genetic processes may be most helpful in accounting for the Cambrian explosion?

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

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 is most directly involved in the evolution of these variations in metamorphosis?

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna?

Suppose a researcher for a pest-control company developed a chemical that inhibited the development of an embryonic mosquito's endodermal cells. Which of the following would be a likely mechanism by which this pesticide works?

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. t. adhaerens' body symmetry seems to be most like that of ________.

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

Which of the following is a feature of the "tube-within-a-tube" body plan in most animal phyla?

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

- Which of the following statements is supported by the phylogeny in the figure?

Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If true, this finding would ________.

The most ancient branch point in animal phylogeny is the characteristic of having ________.

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