BIO II - CH 32

Among the characteristics unique to animals is

The distinction between sponges and other animal phyla is based mainly on the absence versus the presence of

What is the key difference between a coelom and a pseudocoelom?

Select the correct statement about the evolution of animals.

Which feature of deuterostome development explains the formation of identical human twins?

Based on the tree presented in Figure 32.11 in your textbook, which statement is false?

A graduate student finds an organism in a pond and thinks it is a freshwater sponge. A postdoctoral student thinks it looks more like an aquatic fungus. How can they decide whether it is an animal or a fungus?

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

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

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?

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

Trichoplax adhaerens (Tp) 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 2000 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. They move using cilia, and any "edge" can lead. Tp 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. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage. Which of the following Tp traits is different from all other known animals?

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

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 _____.

All animals can trace their lineage to a common ancestor that lived in the _____.

The earliest ancestors of about half of all extant animal phyla can be traced back to the _____ explosion.

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

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

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

Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships? The fossil record reveals an increased incidence of _____.

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 _____.

Arthropods invaded land about 100 million years before vertebrates did so. This most clearly implies that _____.

Which of the following is radially symmetrical?

Gastrulation is the process that directly forms the _____.

An important trend in animal evolution was cephalization. An animal is said to show cephalization when it _____.

Which of the following animals does NOT have a body cavity?

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

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?

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?

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

What do all deuterostomes have in common?

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?

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. This embryo may potentially develop into a(n) _____.

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

Fishes that have swim bladders can regulate their density and, thus, their buoyancy. There are two types of swim bladder: physostomous and physoclistous. The ancestral version is the physostomous version, in which the swim bladder is connected to the esophagus via a short tube (see the figure above). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching." The physoclistous version is more derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder. We should expect the inner wall of the swim bladder to be lined with tissue that is derived from _____.

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

Which of these, if true, would support the claim that the ancestral cnidarians had bilateral symmetry? 1. Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects. 2. Cnidarians have fewer Hox genes than bilaterians. 3. All extant cnidarians, including Nematostella, are diploblastic. 4. β-catenin turns out to be essential for gastrulation in all animals in which it occurs. 5. All cnidarians are acoelomate.

An organism that exhibits cephalization probably also _____.

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 (Tp) 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 2000 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. They move using cilia, and any "edge" can lead. Tp 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. Tp sperm cells have never been observed, nor have embryos past the 64-cell (blastula) stage. Tp's body symmetry seems to be most like that of _____.

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 coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. Cycliophorans have two types of larvae. One type of larva is produced when the digestive system of a female is impregnated by a male. The digestive system then collapses and develops into a larva, which swims away in search of a new host after the surrounding female dies. Which is the embryonic tissue that is apparently most important in forming this type of larva?

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 plummules, 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' _____.

Fossil evidence indicates that the following events occurred in what sequence, from earliest to most recent? 1. Protostomes invade terrestrial environments. 2. Cambrian explosion occurs. 3. Deuterostomes invade terrestrial environments. 4. Vertebrates become top predators in the seas.

What is the probable sequence in which the following clades of animals originated, from earliest to most recent? 1. tetrapods 2. vertebrates 3. deuterostomes 4. amniotes 5. bilaterians

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

Which of the following statements is correct?

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?

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 coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. Using similarities in embryonic development, body symmetry, and other anatomical features to assign an organism to a clade involves _____. 1. cladistics based on body plan 2. molecular-based phylogeny 3. morphology-based phylogeny

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

The Hox genes came to regulate each of the following. From earliest to most recent, in what sequence did these events evolve? 1. identity and position of paired appendages in protostome embryos 2. anterior-posterior orientation of segments in protostome embryos 3. positioning of tentacles in cnidarians 4. anterior-posterior orientation in vertebrate embryos

The last common ancestor of all bilaterians is thought to have had four Hox genes. Most extant cnidarians have two Hox genes, except Nematostella (of β-catenin fame), which has three Hox genes. On the basis of these observations, some have proposed that the ancestral cnidarians were originally bilateral and, in stages, lost Hox genes from their genomes. If true, this would mean that _____.

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

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 coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. Which of these, if discovered among cycliophorans, would cause the most confusion concerning our current understanding of cycliophoran taxonomy?

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 coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. The feeding stage of cycliophorans _____. 1. is autotrophic 2. is sessile 3. captures food in a manner similar to that of animals with lophophores 4. shows radial symmetry

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

If in the future the current molecular evidence regarding animal origins is further substantiated, what will be true of any contrary evidence regarding the origin of animals derived from the fossil record?

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 coelomates, do not molt (though their host does), and their embryos undergo spiral cleavage. Basing your inferences on information in the paragraph above, to which clade(s) should cycliophorans belong? 1. Eumetazoa 2. Deuterostomia 3. Bilateria 4. Ecdysozoa 5. Lophotrochozoa

What conclusion is apparent from the data in the table above?

All things being equal, which of these is the most parsimonious explanation for the change in the number of Hox genes from the last common ancestor of insects and vertebrates to ancestral vertebrates, as shown in the table above?

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 _____.

In the experiment outlined in the figure above, what would you expect to happen if researchers supplied an enzyme that blocked the expression of the Dll gene?

Dll is a gene known to direct limb development in the fruit fly. Researchers studying this gene have found that it is also expressed in developing appendages in animals from many other phyla, supporting the hypothesis that all animal appendages may be homologous. However, suppose researchers looking at Dll activity had instead found the results shown in the figure above. These results suggest instead that _____.

Which of the following statements concerning animal taxonomy is (are) true? 1. Animals are more closely related to plants than to fungi. 2. All animal clades based on body plan have been found to be incorrect. 3. Kingdom Animalia is monophyletic. 4. Animals only reproduce sexually. 5. Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.