Exam 32: An Overview of Animal Diversity

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

What was an early selective advantage of a coelom in animals? A coelom ________.

Sponges and ctenophores have both been proposed as basal metazoans. Imagine that you wanted to provide additional evidence to help resolve this question. Which of the following projects would be the best next step?

Use the information to answer the question. One small animal phylum (Placozoa) contains only two species, Trichoplax adhaerens (T. adhaerens) and T. reptans. T. adhaerens is the only species seen in over a century. 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. Embryos up to, but not past, the 64-cell (blastula) stage have been observed. On the basis of information in the paragraph, which of these should be able to be observed in T. adhaerens?

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

Use the figure to answer the question. Which morphological trait evolved more than once in animals, according to the phylogeny based on DNA sequence data found in the figure?

What do animals ranging from corals to monkeys have in common?

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________.

Soon after the coelom begins to form, a researcher injects a dye into the coelom of a deuterostome embryo. Initially, the dye should be able to flow directly into the ________.

You have before you a living organism, which you examine carefully. Which of the following should convince you that the organism is acoelomate?

Sponges and ctenophores have both been proposed as basal metazoans. Which of the following types of data support the idea that sponges are the basal group?

Which of the following was probably the least important factor in bringing about the Cambrian explosion?

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

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?

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?

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

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 collagen?

Based on the tree shown, which statement is false?

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?

You find a new species of worm and want to classify it. Which of the following lines of evidence would allow you to classify the worm as a nematode and not an annelid?