Exam 32: An Overview of Animal Diversity

Use the following information to answer the questions below. The most recently discovered phylum in the animal kingdom (1995) is the phylum Cycliophora. It includes three species of tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk, and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is sac-like and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are eucoelomate, do not moult (though their host does), and their embryos undergo spiral cleavage. -On the basis of the cleavage pattern of cycliophoran embryos, which of these should be true?

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

Two competing hypotheses to account for the increase in the number of Hox genes from the last common ancestor of bilaterians to the last common ancestor of insects and vertebrates are (1)a single duplication of the entire four-gene cluster, followed by the loss of one gene, and (2)three independent duplications of individual Hox genes. To prefer the first hypothesis on the basis of parsimony requires the assumption that

Use the following information to answer the questions 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 to lie in the grooves between larger, underlying cells (i.e., spiral cleavage). -This embryo may potentially develop into a(n)

An adult animal that possesses bilateral symmetry is most certainly also

Which distinction is given more emphasis by the morphological phylogeny than by the molecular phylogeny?

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

Placozoan evolutionary relationships to other animals are currently unclear, and different phylogenies can be created, depending on the character used to infer relatedness. Sponges have no tissues, but about 20 cell types. Tp (Trichoplax adhaerens) produces a neuropeptide almost identical to one found in cnidarians. The genome of Tp, though the smallest of any known animal, shares many features of complex eumetazoan (even human!) genomes. Use the phylogenetic trees that follow to answer the questions below. I II III -Which phylogeny has been created by emphasizing a protein found in placozoans?

At which developmental stage should one be able to first distinguish a diploblastic embryo from a triploblastic embryo?

In individual insects of some species, whole chromosomes that carry larval genes are eliminated from the genomes of somatic cells at the time of metamorphosis. A consequence of this occurrence is that

The last common ancestor of all animals was probably a

What criteria differentiates a pseudocoelomate versus a coelomate animal?

At which developmental stage should one be able to first distinguish a protostome embryo from a deuterostome embryo?

Use the following information to answer the questions below. The most recently discovered phylum in the animal kingdom (1995) is the phylum Cycliophora. It includes three species of tiny organisms that live in large numbers on the outsides of the mouthparts and appendages of lobsters. The feeding stage permanently attaches to the lobster via an adhesive disk, and collects scraps of food from its host's feeding by capturing the scraps in a current created by a ring of cilia. The body is sac-like and has a U-shaped intestine that brings the anus close to the mouth. Cycliophorans are eucoelomate, do not moult (though their host does), and their embryos undergo spiral cleavage. -Basing your inferences on information in the previous paragraph, to which clade(s)should cycliophorans belong? 1. Eumetazoa 2. Deuterostomia 3. Bilateria 4. Ecdysozoa 5. Lophotrochozoa

Phylogenetic trees are best described as

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

Which developmental mode is correctly matched with the specific characteristics?

The figure above shows a chart of the animal kingdom set up as a modified phylogenetic tree. Use the diagram to answer the following questions. -Which group contains diploblastic organisms?

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

What does recent evidence from molecular systematics reveal about the relationship between grades and clades?