Exam 32: An Overview of Animal Diversity

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

The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, though some have three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarian's were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that ________.

If you think of the earthworm body plan as a drinking straw within a pipe, where would you expect to find most of the tissues that developed from endoderm?

An organism that exhibits a head with sensory equipment and a brain probably also ________.

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

Which of the following would you classify as something other than an animal?

Cadherin proteins help animal cells stick (adhere) to each other. Choose which statement about cadherin in cancer cells that are metastasizing (spreading) throughout a patient's body is most likely correct.

Which of the following statements concerning animal taxonomy is accurate?

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. If we were to separate these eight cells and attempt to culture them individually, then what is most likely to happen?

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

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

Which of the following statements comparing symmetry in sessile and swimming animals is most probable?

In the future, phylogenetic studies should be conducted to ________.

If in the future the current molecular evidence regarding animal origins is further substantiated, which of the following statements would be correct with reference to fossil evidence that contradicts molecular evidence?

What do all deuterostomes have in common?

Nine-banded armadillos give birth to four offspring at a time. An amazing fact about these offspring is that they are genetically identical to each other. This fact suggests ________.

The last common ancestor of all animals was probably a ________.

While looking at some seawater through your microscope, you spot the egg of an unknown animal. Which of the following tests could you use to determine whether the developing organism is a protostome or a deuterostome? See whether the embryo ________.

In examining an unknown animal species during its embryonic development, how can you be sure what you are looking at is a protostome and not a deuterostome?

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. Which organism would you classify as an animal?