bio 101 ch 32

Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.

Which of the following statements concerning animal taxonomy is accurate? Kingdom Animalia is polyphyletic. In the kingdom Animalia, most clades based on body plan or fossils have been found to be incorrect. Animals are more closely related to plants than to fungi. Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.

The mouth and anus form the ends of the inner tube.

Which of the following is a feature of the "tube-within-a-tube" body plan in most animal phyla? The two "tubes" are separated by tissue that comes from embryonic endoderm. The outer tube consists of digestive organs. The outer tube consists of a hard exoskeleton. The mouth and anus form the ends of the inner tube.

Bilaterally symmetric animals can be streamlined for swimming, but radially symmetric animals cannot.

Which of the following statements comparing symmetry in sessile and swimming animals is most probable? Radial symmetry is more advantageous for active swimming than is bilateral symmetry. Radial symmetry occurs most frequently in animals that catch their prey by rapid swimming. Bilaterally symmetric animals can be streamlined for swimming, but radially symmetric animals cannot. Bilateral symmetry allowed animals to evolve nerves.

Animals with extremely different adult forms can be relatively closely related.

Which of the following statements is supported by the phylogeny in the figure? Animals with extremely different adult forms can be relatively closely related. Animals show no evidence of convergent evolution in their traits. Deuterostoma are more evolutionarily advanced than Porifera. Traits, once they evolve, are retained in later-evolving taxonomic groups.

choanoflagellate

Which of the following would you classify as something other than an animal? sponge choanoflagellate jellyfish coral

Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects.

Which of these statements, if accurate, would support the claim that the ancestral cnidarians had bilateral symmetry? Cnidarian larvae possess anterior-posterior, left-right, and dorsal-ventral aspects. The presence of collar cells. All cnidarians are acoelomate. Cnidarians have fewer Hox genes than bilaterians.

nervous: mesoderm

Which tissue type or organ is not correctly matched with its germ layer tissue? stomach: endoderm skin: ectoderm nervous: mesoderm muscular: mesoderm

asymmetry: sponge radial symmetry: jelly, hydra bilateral symmetry: bobcat, octopus, turtle, snake

Which type of symmetry does each of the following animals display? asymmetry, radial symmetry, bilateral symmetry a. Jelly b. sponge c. bobcat d. turtle e. hydra f. snake g. octopus

Molecular data can be used to give an estimate of the time since two groups split.

Why might researchers choose to use molecular data (such as ribosomal RNA sequences) rather than morphological data to study the evolutionary history of animals? Morphological changes usually do not result from molecular changes. Some phyla vary too widely in morphological characteristics to be classified accurately. Molecular data can be gathered in the lab, while morphological data must be gathered in the field. Molecular data can be used to give an estimate of the time since two groups split.

It sheds its external skeleton to grow.

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? It sheds its external skeleton to grow. It is segmented. It is triploblastic. It has a coelom.

collagen genes

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? a. genes involved in eye-lens synthesis b. collagen genes c. genes involved in chitin synthesis d. genes involved in directing segmentation development

earthworm

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. This embryo may potentially develop into a(n) ________. sea star turtle earthworm sea urchin

type of body cavity (coelom versus pseudocoelom versus no coelom)

Among protostomes, which morphological trait has shown the most variation? type of symmetry (bilateral versus radial versus none) type of body cavity (coelom versus pseudocoelom versus no coelom) type of development (protostome versus deuterostome) number of embryonic tissue types (diploblasty versus triploblasty)

In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity. A diploblast has no mesoderm. A pseudocoelom has the same functions as a true coelom.

Animal tissues develop from embryonic germ layers. Triploblastic animals have three germ layers (ectoderm, mesoderm, and endoderm) and three basic body plans related to body cavities (acoelomate, pseudocoelomate, and coelomate). Select the three statements that are true. a. The digestive tract of a coelomate functions as a coelom. b. In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the tissue lining the outer side of the body cavity. c. A diploblast has no mesoderm. An acoelomate triploblast has no endoderm. d. In a pseudocoelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the muscles. e. In a coelomate, the tissue lining the inner side of the body cavity arises from the same germ layer as the lining of the digestive tract. f. A pseudocoelom has the same functions as a true coelom.

arthropods have had more time to coevolve with land plants than have vertebrates

Arthropods invaded land about 100 million years before vertebrates. This fact most clearly implies that ________. arthropods have had more time to coevolve with land plants than have vertebrates vertebrates evolved from arthropods extant terrestrial arthropods are better adapted to terrestrial life than are extant terrestrial vertebrates arthropods evolved before vertebrates did

Organism B

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 photosynthetic genes? a. organism A b. organism B c. organism C d. organism D

Every phylogeny should be considered a hypothesis that must be revised in the light of new data.

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? Every phylogeny should be considered a hypothesis that must be revised in the light of new data. We need more fossil evidence of sponges. Molecular and morphological data often conflict when we try to reconstruct evolutionary history. The goal of making all taxonomic groups monophyletic is unrealistic.

ingesting materials

Both animals and fungi are heterotrophic. What distinguishes animal heterotrophy from fungal heterotrophy is that most animals derive their nutrition by ________. a. preying on animals b. using enzymes to digest their food c. consuming living, rather than dead, prey d. ingesting materials

hard parts

Evidence of which structure or characteristic would be most surprising to find among fossils of the Ediacaran fauna? bilateral symmetry embryos hard parts true tissues

You see a mouth, but not an anus

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? The animal is clearly bilaterally symmetrical. There is evidence of cephalization. You see a mouth, but not an anus The animal is triploblastic.

The removal of the acoel flatworms (Acoela) from the Platyhelminthes allowed the remaining flatworms to be a monophyletic clade clearly tied to the Lophotrochozoa.

In the traditional phylogeny (A), the phylum Platyhelminthes is depicted as a sister taxon to the rest of the protostome phyla and as having diverged earlier from the lineage that led to the rest of the protostomes. In the molecular phylogeny (B), Platyhelminthes is depicted as a Lophotrochozoan phylum. What probably led to this change? Platyhelminthes' close genetic ties to the arthropods became clear as their Hox gene sequences were studied. The removal of the acoel flatworms (Acoela) from the Platyhelminthes allowed the remaining flatworms to be a monophyletic clade clearly tied to the Lophotrochozoa. All Platyhelminthes must have a well-developed lophophore as their feeding apparatus. Platyhelminthes ceased to be recognized as true protostomes.

Protostome: mouth from blastospore, spiral, determinate cleavage, coelom from solid masses of mesoderm Deuterostome: anus from blastospore, radial, indeterminate cleavage, coelom from folds of archenteron Both: Triploblast Neither: Diploblast

Many animals can be categorized as either protostomes and deuterostomes based on certain features of their embryonic development. Determine whether each of the following terms applies to only protostomes, only deuterostomes, both protostomes and deuterostomes, or neither. a. anus from blastospore b. spiral, determinate cleavage c. triploblast d. coelom from solid masses of mesoderm e. radial, indeterminate cleavage f. coelom from folds of archenteron g. diploblast h. mouth from blastospore

the embryo undergoes radial and indeterminate cleavage

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 first cell division of the fertilized egg is perpendicular to the vertical axis of the egg the embryo undergoes radial and indeterminate cleavage the species is pseudocoelomate the young undergo metamorphosis

hard parts

One hypothesis suggests that the Cambrian explosion was caused by the rise of predator-prey relationships. This hypothesis is best supported by an increased incidence of which of the following fossil traces? organic material hard parts larger animals worm burrows

is bilaterally symmetrical

Part complete An organism that exhibits a head with sensory equipment and a brain probably also ________. is segmented is bilaterally symmetrical is diploblastic has a coelom

Sponge ancestors never had tissues.

Placing sponges as the basal metazoans on the basis of lack of tissues implies which of the following? Multicellular, modern-day choanoflagellates can form tissues. Sponges do not have nerve cells. Sponge ancestors never had tissues. Modern-day sponges have lost the ability to form tissues.

confirm the identity of sponges as "basal animals"

Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If true, this finding would _____. mean that extinct sponges must have been the last common ancestor of animals and fungi require sponges to be reclassified as choanoflagellates mean that sponges must no longer be classified as animals confirm the identity of sponges as "basal animals"

archenteron

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 _____. blastocoel archenteron pseudocoelom blastopore

fossil steroids, molecular clock, lack of tissues in sponges, and structure of collar cells

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? sequences of collagen genes, bilateral symmetry of adults, cleavage type, and fossil steroids fossil steroids, molecular clock, lack of tissues in sponges, and structure of collar cells structure of collar cells, bilateral symmetry of larvae, sequences of cadherin genes, and molecular clock sequences of cadherin genes, cleavage type, structure of collar cells, and bilateral symmetry of adults

The body cavity evolved before the lophophore.

The common ancestor of the protostomes had a coelom. What does this suggest? There are no pseudocoelomates within the protostomes. There are no acoelomates within the protostomes. All lophotrochozoans have a coelom. The body cavity evolved before the lophophore.

sense, feed, and move

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 ________. form an embryo and establish a basic body plan arrange cells into tissues reproduce sense, feed, and move

choanoflagellates and sponges are sister groups

The fact that choanoflagellates and collar cells of sponges resemble each other supports the inference that ________. a. choanoflagellates and sponges are sister groups b. choanoflagellates are animals c. choanoflagellates are more closely related to sponges than they are to protists d. choanoflagellates and sponges evolved similar cell structures through convergent evolution

the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait

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 ________. Hox genes play little actual role in coding for an animal's "body plan" the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait cnidaria may someday replace porifera as the basal bilaterians all radially symmetric animals should be grouped together in one clade

true tissues or no tissues

The most ancient branch point in animal phylogeny is the characteristic of having _____. radial or bilateral symmetry diploblastic or triploblastic embryos true tissues or no tissues a body cavity or no body cavity

development of a head

Use the information to answer the question. 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 plumules, 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' ________. segmentation development of a head lack of torsion identity as lophotrochozoans

eggs

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 m 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? the process of gastrulation a radially symmetric larval form a coelom eggs

most sponges

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 ________. most sponges cnidarians worms tetrapods

Organism C

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? a. organism A b. organism B c. organism C d. organism D

The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.

Use the table to answer the question. What conclusion can best be drawn from the data in the table? Extant insects all have seven Hox genes. The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster. All bilaterian phyla have had the same degree of expansion in their numbers of Hox genes. Land animals have more Hox genes than do those that live in water.

The pore (blastopore) formed during gastrulation becomes the anus.

What do all deuterostomes have in common? Adults are bilaterally symmetrical. Embryos have pharyngeal pouches that may or may not form gill slits. All have a spinal column. The pore (blastopore) formed during gastrulation becomes the anus.

presence of Hox genes

What do animals ranging from corals to monkeys have in common? a. number of embryonic tissue layers b. presence of Hox genes c. some type of body symmetry d. a mouth and an anus

contributed to a hydrostatic skeleton, allowing greater range of motion

What was an early selective advantage of a coelom in animals? A coelom _____. allowed asexual and sexual reproduction was a more efficient digestive system allowed cephalization and the formation of a cerebral ganglion contributed to a hydrostatic skeleton, allowing greater range of motion

adaptive radiation

Whatever its ultimate cause(s), the Cambrian explosion is a prime example of _____. a large meteor impact adaptive radiation mass extinction evolutionary stasisa

the body shapes we see now have been more successful than others in the past

When a scientist describes the "body plan" of a phylum, he or she is implying that ________. the body shapes we see now have been more successful than others in the past animals evolve according to a pre-ordained plan organisms direct their own evolution in order to maximize their success mutations have arisen that allow only some shapes to be produced

Segmentation

Which morphological trait evolved more than once in animals, according to the phylogeny based on DNA sequence data found in the figure? bilateral symmetry coelom segmentation protostome development

predation by new species, faster movement by new species, and increased developmental flexibility by new species

Which of the following factors most likely contributed to the extinction of many Ediacaran life forms? loss of habitat due to increased temperatures, poisoning from high oxygen levels, and loss of developmental flexibility predation by new species, poisoning from high oxygen levels, and loss of habitat due to increased temperatures predation by new species, poisoning from high carbon dioxide levels, and loss of developmental flexibility predation by new species, faster movement by new species, and increased developmental flexibility by new species

nervous system signal conduction and muscular movement

Which of the following is (are) unique to animals? a. nervous system signal conduction and muscular movement b. the structural carbohydrate, chitin c. flagellated gametes d. heterotrophy