Deck 32: An Overview of Animal Diversity

Question 1

Which of the following traits differentiates animals from plants and fungi?

A)are eukaryotes
B)contain collagen
C)are multicellular
D)have a cell wall
E)A and D

Answer 1

B

Question 2

An adult animal that possesses bilateral symmetry is most certainly also

A)triploblastic.
B)a deuterostome.
C)eucoelomate.
D)highly cephalized.

Answer 2

A

Question 3

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

A)preying on animals.
B)ingesting it.
C)consuming living, rather than dead, prey.
D)using enzymes to digest their food.

Answer 3

B

Question 4

What is the correct sequence (from most ancient to most recent)of milestones in the evolution of animals?

A)choanoflagellates, Ediacaran biota, Cambrian explosion, successful invasion of land,? origin of flight
B)choanoflagellates, Cambrian explosion, Ediacaran biota, successful invasion of land,? origin of flight
C)Ediacaran biota, choanoflagellates, Cambrian explosion, successful invasion of land,? origin of flight
D)Cambrian explosion, choanoflagellates, Ediacaran biota, successful invasion of land,? origin of flight
E)choanoflagellates, Cambrian explosion, successful invasion of land, Ediacaran biota,? origin of flight

Question 5

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

A)we could not clone a larva from the somatic cells of such an adult insect.
B)such species must reproduce only asexually.
C)the descendents of these adults do not include a larval stage.
D)metamorphosis can no longer occur among the descendents of such adults.
E)Two of these responses are correct.

Question 6

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

A)blastopore.
B)blastocoel.
C)archenteron.
D)pseudocoelom.

Question 7

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

A)true tissues
B)hard parts
C)bilateral symmetry
D)cephalization
E)embryos

Question 8

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 most directly favours the evolution of the latter, more radical, kind of metamorphosis?

A)natural selection of sexually immature forms of insects
B)changes in the homeobox genes governing early development
C)the evolution of meiosis
D)the development of an oxidizing atmosphere on Earth
E)the origin of a brain

Question 9

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

A)cells that have mitochondria
B)the structural carbohydrate, chitin
C)nervous conduction and muscular movement
D)heterotrophy
E)Two of these responses are correct.

Question 10

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

A)arthropods evolved before vertebrates did.
B)extant terrestrial arthropods are better adapted to terrestrial life than are extant terrestrial vertebrates.
C)ancestral arthropods must have been poorly adapted to aquatic life, and thus experienced a selective pressure to invade land.
D)vertebrates evolved from arthropods.
E)arthropods have had more time to coevolve with land plants than have vertebrates.

Question 11

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.

A)2 → 4 → 3 → 1
B)2 → 1 → 4 → 3
C)2 → 4 → 1 → 3
D)2 → 3 → 1 → 4
E)2 → 1 → 3 → 4

Question 12

The Hox genes came to regulate each of the following in what sequence, from earliest to most recent? 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

A)4 → 1 → 3 → 2
B)4 → 2 → 3 → 1
C)4 → 2 → 1 → 3
D)3 → 2 → 1 → 4
E)3 → 4 → 1 → 2

Question 13

The last common ancestor of all animals was probably a

A)unicellular chytrid.
B)unicellular yeast.
C)multicellular algae.
D)multicellular fungus.
E)flagellated protist.

Question 14

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

A)mass extinction.
B)evolutionary stasis.
C)adaptive radiation.
D)All three of the responses are correct.
E)Only two of the responses are correct.

Question 15

When you consider the evolutionary history of animals, what are some plausible explanations for the diversification and extinction of some animal species?

A)Animal form and function changed as new adaptations evolved, resulting in new predator-prey interactions.
B)Some animals adapted better to the atmospheric and environmental changes than others.
C)Soft-bodied animals and small-sized animals evolve faster but also go extinct faster.
D)Less complex animals are always first to go extinct.
E)A and B

Question 16

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

A)5 → 3 → 2 → 4 → 1
B)5 → 3 → 2 → 1 → 4
C)5 → 3 → 4 → 2 → 1
D)3 → 5 → 4 → 2 → 1
E)3 → 5 → 2 → 1 → 4

Question 17

What do animals as diverse as corals and monkeys have in common?

A)body cavity between body wall and digestive system
B)number of embryonic tissue layers
C)type of body symmetry
D)presence of Hox genes
E)degree of cephalization

Question 18

Which statement is most consistent with the hypothesis that the Cambrian explosion was caused by the rise of predator-prey relationships?

A)increased incidence of worm burrows in the fossil record
B)increased incidence of larger animals in the fossil record
C)increased incidence of organic material in the fossil record
D)increased incidence of fern galls in the fossil record
E)increased incidence of hard parts in the fossil record

Question 19

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?

A)genes involved in chitin synthesis
B)collagen genes
C)β-catenin genes
D)genes involved in eye-lens synthesis
E)genes that cause radial body symmetry

Question 20

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

A)binary fission
B)mitosis
C)random segregation
D)gene duplication
E)chromosomal condensation

Question 21

According to the evidence collected so far, the animal kingdom is

A)monophyletic.
B)paraphyletic.
C)polyphyletic.
D)euphyletic.
E)multiphyletic.

Question 22

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

A)There is no relationship.
B)Some, but not all, grades reflect evolutionary relatedness.
C)Grades have their basis in, and flow from, clades.
D)Each branch point on a phylogenetic tree is associated with the evolution of a new grade.

Question 23

With the current molecular-based phylogeny in mind, rank the following from most inclusive to least inclusive. 1. ecdysozoan
2. protostome
3. eumetazoan
4. triploblastic

A)4, 2, 3, 1
B)4, 3, 1, 2
C)3, 4, 1, 2
D)3, 4, 2, 1
E)4, 3, 2, 1

Question 24

What is true of the clade Ecdysozoa?

A)It includes all animals that moult at some time during their lives.
B)It includes all animals that undergo metamorphosis at some time during their lives.
C)It includes all animals that have body cavities known as pseudocoeloms.
D)It includes all animals with genetic similarities that are shared with no other animals.
E)It includes all animals in the former clade Protostomia that truly do have protostome development.

Question 25

Protostome characteristics generally include which of the following?

A)a mouth that develops secondarily, and far away from the blastopore
B)radial body symmetry
C)radial cleavage
D)determinate cleavage
E)absence of a body cavity

Question 26

The blastopore denotes the presence of an endoderm-lined cavity in the developing embryo, a cavity that is known as the

A)archenteron.
B)blastula.
C)coelom.
D)germ layer.
E)blastocoel.

Question 27

Which developmental mode is correctly matched with the specific characteristics?

A)protostome - spiral cleavage, folds of archenteron form the coelom, mouth develops from blastopore
B)protostome - spiral cleavage, folds of archenteron form the coelom, anus develops from blastopore
C)deuterostome - spiral cleavage, masses of mesoderm split and form the coelom, mouth develops from blastopore
D)deuterostome - radial cleavage, folds of archenteron form the coelom, anus develops from blastopore
E)protostome - radial cleavage, folds of archenteron form the coelom, mouth develops from blastopore

Question 28

Which of the following is descriptive of protostomes?

A)spiral and indeterminate cleavage, blastopore becomes mouth
B)spiral and determinate cleavage, blastopore becomes mouth
C)spiral and determinate cleavage, blastopore becomes anus
D)radial and determinate cleavage, blastopore becomes anus
E)radial and determinate cleavage, blastopore becomes mouth

Question 29

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

A)fertilization
B)cleavage
C)gastrulation
D)coelom formation
E)metamorphosis

Question 30

What criteria differentiates a pseudocoelomate versus a coelomate animal?

A)A pseudocoelomate animal is diploblastic and the body cavity is partially lined by endoderm.
B)A pseudocoelomate animal is diploblastic and the body cavity is completely lined by mesoderm.
C)A coelomate animal is triploblastic and the body cavity is completely lined by mesoderm.
D)A coelomate animal is triploblastic and the body cavity is completely lined by endoderm.
E)A coelomate animal is diploblastic and the body cavity is completely lined by mesoderm.

Question 31

If a multicellular animal lacks true tissues, then it can properly be included among the

A)eumetazoans.
B)metazoans.
C)choanoflagellates.
D)lophotrochozoans.
E)bilateria.

Question 32

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

A)The contrary fossil evidence will be seen as a hoax.
B)The fossil evidence will be understood to have been incorrect because it is incomplete.
C)The fossil record will henceforth be ignored.
D)Phylogenies involving even the smallest bit of fossil evidence will need to be discarded.
E)Only phylogenies based solely on fossil evidence will need to be discarded.

Question 33

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

A)fertilization
B)cleavage
C)gastrulation
D)coelom formation
E)metamorphosis

Question 34

The most ancient branch point in animal phylogeny is that between having

A)radial or bilateral symmetry.
B)a well-defined head or no head.
C)diploblastic or triploblastic embryos.
D)true tissues or no tissues.
E)a body cavity or no body cavity.

Question 35

Which of the following characteristics generally applies to protostome development?

A)radial cleavage
B)determinate cleavage
C)diploblastic embryo
D)blastopore becomes the anus
E)archenteron absent

Question 36

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

A)It is triploblastic.
B)It has bilateral symmetry.
C)It possesses sensory structures at its anterior end.
D)Muscular activity of its digestive system distorts the body wall.

Question 37

What distinguishes a coelomate animal from a pseudocoelomate animal is that coelomates

A)have a body cavity, whereas pseudocoelomates have a solid body.
B)contain tissues derived from mesoderm, whereas pseudocoelomates have no such tissue.
C)have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.
D)have a complete digestive system with mouth and anus, whereas pseudocoelomates have a digestive tract with only one opening.
E)have a gut that lacks suspension within the body cavity, whereas pseudocoelomates have mesenteries that hold the digestive system in place.

Question 38

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. Only animals reproduce by sexual means.
5. Animals are thought to have evolved from flagellated protists similar to modern choanoflagellates.

A)5 only
B)1 and 3
C)3 and 5
D)3, 4, and 5

Question 39

Phylogenetic trees are best described as

A)true and inerrant statements about evolutionary relationships.
B)hypothetical portrayals of evolutionary relationships.
C)the most accurate representations possible of genetic relationships among taxa.
D)theories of evolution.
E)the closest things to absolute certainty that modern systematics can produce.

Question 40

The blastopore is a structure that first becomes evident during

A)fertilization.
B)gastrulation.
C)the eight-cell stage of the embryo.
D)coelom formation.
E)cleavage.

Question 41

Use the following information to answer the questions below.
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.
On the basis of information in the previous paragraph, which of these should be able to be observed in Tp?

A)the act of fertilization
B)the process of gastrulation
C)eggs
D)All three of the responses above are correct.
E)Two of the responses above are correct.

Question 42

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 genomic features of placozoans?

A)I
B)II
C)III

Question 43

Use the following information to answer the questions below.
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.
If Tp sperm are observed by future researchers, how many chromosomes should be found in a Tp sperm nucleus?

A)2
B)3
C)6
D)12

Question 44

Use the following information to answer the questions below.
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.
In how many of the following ways is Tp unlike the typical animal? 1. Tp is multicellular.
2. Tp lacks muscle and nerve cells.
3. Tp has cilia.
4. Tp has a different place where digestion of food occurs.
5. Tp lacks cell walls.

A)only one way
B)two ways
C)three ways
D)four ways
E)all five ways

Question 45

Which of the following statements is incorrect with respect to animal phylogeny?

A)Sponges are basal animals.
B)Eumetazoans are animals with "true tissues."
C)The clade Bilateria contains the majority of animal phyla.
D)Only vertebrates belong to the clade Deuterostomia.
E)B and D

Question 46

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
Cycliophorans have two types of larvae. One type of larva-the Prometheus larva-develops into a male. The male, which lacks a digestive system, attaches to the outside of a feeding stage (a female)and impregnates her digestive system, which develops into a different type of larva. What must be true of the digestive system of the feeding-stage female while she is still a virgin? 1. At least some of its cells are haploid.
2. It consists only of highly specialized cells.
3. It is the same size as the male.

A)1 only
B)2 only
C)3 only
D)1 and 3
E)2 and 3

Question 47

Use the following two diagrams (A and B) to answer the questions below.

A: Morphological phylogeny.

B: Molecular phylogeny.
What is true of the deuterostomes in the molecular phylogeny (B)that is not true in the traditional phylogeny (A)?

A)Deuterostomia is a clade.
B)To maintain Deuterostomia as a clade, some phyla had to be removed from it.
C)Deuterostomia now includes the Acoela.
D)It is actually a grade, rather than a clade.
E)It diverged from the rest of the Bilateria earlier than did the Acoela.

Question 48

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?

A)I
B)II
C)III

Question 49

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 two groups have members that undergo ecdysis?

A)I and II
B)II and III
C)III and IV
D)III and V
E)IV and V

Question 50

Use the following two diagrams (A and B) to answer the questions below.

A: Morphological phylogeny.

B: Molecular phylogeny.
According to the phylogenies depicted in the previous pair of figures, if one were to create a taxon called Radiata that included all animal species whose members have true radial symmetry, then such a taxon would be

A)paraphyletic.
B)polyphyletic.
C)monophyletic.
D)a clade.
E)More than one of these responses are correct.

Question 51

Use the following two diagrams (A and B) to answer the questions below.

A: Morphological phylogeny.

B: Molecular phylogeny.
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?

A)Platyhelminthes ceased to be recognized as true protostomes.
B)The removal of the acoel flatworms (Acoela)from the Platyhelminthes allowed the remaining flatworms to be clearly tied to the Lophotrochozoa.
C)All Platyhelminthes must have a well-developed lophophore as their feeding apparatus.
D)Platyhelminthes' close genetic ties to the arthropods became clear as their Hox gene sequences were studied.

Question 52

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.

A)1 only
B)1 and 4
C)2 and 3
D)2 and 4
E)4 and 5

Question 53

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 two groups are most clearly represented in the Ediacaran fauna?

A)I and II
B)I and III
C)II and IV
D)II and V
E)IV and V

Question 54

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

A)Radiata should be a true clade.
B)the radial symmetry of extant cnidarians is secondarily derived, rather than being an ancestral trait.
C)Hox genes play little actual role in coding for an animal's "body plan."
D)Cnidaria may someday replace Acoela as the basal bilaterians.
E)Two of the responses above are correct.

Question 55

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 the structural simplicity of placozoans?

A)I
B)II
C)III

Question 56

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?

A)I
B)II
C)III
D)IV
E)V

Question 57

Use the following information to answer the questions below.
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.
In its native environment, a Tp cell neither gains nor loses water. What should one expect to occur when Tp is placed into fresh water?

A)No change, as fresh water is its native environment
B)lysis
C)plasmolysis
D)slight shrinkage

Question 58

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 of these is the basal group of the Eumetazoa?

A)I
B)II
C)III
D)IV
E)V

Question 59

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

A)strengthen sponges' evolutionary ties to the Eumetazoa.
B)mean that sponges must no longer be classified as animals.
C)confirm the identity of sponges as "basal animals."
D)mean that extinct sponges must have been the last common ancestor of animals and fungi.
E)require sponges to be reclassified as choanoflagellates.

Question 60

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

A)metazoan and eumetazoan
B)radial and bilateral
C)true coelom and pseudocoelom
D)protostome and deuterostome
E)moulting and lack of moulting

Question 61

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)

A)turtle.
B)earthworm.
C)sea star.
D)fish.
E)sea urchin.

Question 62

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

A)a body cavity.
B)a complete digestive tract.
C)a circulatory system.
D)true tissues.
E)mesoderm.

Question 63

The following questions refer to the description below.
You have taken an introductory course in animal biology and know that animals have evolved with different types of symmetry. Animals that show radial symmetry have a top and bottom, but do not have a left or right side, nor a front or back end. Animals that show bilateral symmetry have a top and bottom, left and right sides, and distinct anterior and posterior ends.
Why do you think that evolution of cephalization is correlated with the evolution of bilateral symmetry?

A)Bilaterally symmetrical animals are better adapted in aquatic environments where animals first evolved.
B)As organisms needed to get smarter, an anterior end with a head region evolved.
C)Bilaterally symmetrical animals have an anterior end that contains sensory material/brain region.
D)If animals want to move backward, they need to have a front and back end.
E)Two of the above are correct.

Question 64

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?

A)It has determinate development.
B)The blastopore becomes the anus.
C)They are deuterostomes.
D)A cell separated from a four-cell embryo should develop into a complete organism.

Question 65

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.
What is true of the feeding stage of cycliophorans? 1. It is chemoheterotrophic.
2. It is sessile.
3. It captures food in a manner similar to that of animals with lophophores.
4. It has radial symmetry.

A)1 and 2
B)1 and 3
C)2 and 4
D)1, 2, and 3
E)2, 3, and 4

Question 66

Among the characteristics unique to animals is

A)gastrulation.
B)multicellularity.
C)sexual reproduction.
D)flagellated sperm.
E)heterotrophic nutrition.

Question 67

Use the following table to answer the questions below.
Proposed Number of Hox Genes in Various Extant and Extinct Animals

What conclusion is apparent from the data in the table?

A)Land animals have more Hox genes than do those that live in water.
B)All bilaterian phyla have had the same degree of expansion in their numbers of Hox genes.
C)Acoel flatworms should be expected to contain seven Hox genes.
D)The expansion in number of Hox genes throughout vertebrate evolution cannot be explained merely by three duplications of the ancestral vertebrate Hox cluster.
E)Extant insects all have seven Hox genes.

Question 68

Use the following table to answer the questions below.
Proposed Number of Hox Genes in Various Extant and Extinct Animals

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?

A)The occurrence of seven independent duplications of individual Hox genes.
B)The occurrence of two distinct duplications of the entire seven-gene cluster, followed by the loss of one cluster.
C)The occurrence of a single duplication of the entire seven-gene cluster.

Question 69

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.
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.

A)1 only
B)2 only
C)3 only
D)1 and 2
E)1 and 3

Question 70

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.
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?

A)mesohyl
B)mesoderm
C)ectoderm
D)endoderm
E)mesoglea

Question 71

Acoelomates are characterized by

A)the absence of a brain.
B)the absence of mesoderm.
C)deuterostome development.
D)a coelom that is not completely lined with mesoderm.
E)a solid body without a cavity surrounding internal organs.

Question 72

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

A)All eight cells will die immediately.
B)Each cell may continue development, but only into a nonviable embryo that lacks many parts.
C)Each cell may develop into a full-sized, normal embryo.
D)Each cell may develop into a smaller-than-average, but otherwise normal, embryo.

Question 73

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.
If harbouring large populations of cycliophorans neither helps nor harms their lobster hosts, then cycliophorans can be properly considered to be 1. parasites.
2. mutualists.
3. commensals.
4. symbionts.
5. endosymbionts.

A)1 and 4
B)2 and 4
C)3 and 4
D)2 and 5
E)3 and 5

Question 74

The following questions refer to the description below.
You have taken an introductory course in animal biology and know that animals have evolved with different types of symmetry. Animals that show radial symmetry have a top and bottom, but do not have a left or right side, nor a front or back end. Animals that show bilateral symmetry have a top and bottom, left and right sides, and distinct anterior and posterior ends.
You and a friend have flown to the coast of British Columbia to do some hiking and whale watching. As you are walking along the beach collecting shells, you notice a strange animal washed up on the beach and it is not a species that you recognize. Just by looking at the animal, what is a quick way that you can surmise the animal's mode of locomotion and method of food acquisition?

A)You need to put it back into the water and observe it.
B)Bilaterally symmetrical animals will show directed movement while radially symmetrical animals tend to be sedentary.
C)Bilaterally symmetrical animals will likely capture prey, while radially symmetrical animals will likely be filter feeders.
D)Bilaterally symmetrical animals will likely feed as they move fast, while radially symmetrical animals will likely move slower and feed on injured or dead prey.
E)B and C

Question 75

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

A)the duplication of a cluster of four Hox genes is equally as likely as the duplication of a single Hox gene.
B)there is an actual process by which individual genes can be duplicated.
C)genes can exist is spatial groupings called clusters.
D)clusters of genes can undergo disruption, with individual genes moving to different chromosomes during evolution.

Question 76

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

A)1 only
B)1 and 3
C)1, 3, and 5
D)2, 3, and 4
E)2, 3, and 5

Question 77

Use the following information to answer the questions below.
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

A)most sponges.
B)cnidarians.
C)worms.
D)tetrapods.
E)Two of the responses above are correct.

Question 78

Use the following information to answer the questions below.
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.
In an experiment, several Tp individuals were stained different colours. The stained individuals were then passed through a strainer, disaggregated to the level of single cells, and collected into a common container of sea water. Which subsequent finding would be most surprising if the Tp individuals used in this experiment had been produced by sexual, rather than asexual, means?

A)If all of the cells from a given individual reaggregated to form the same individual, and if each cell had retained its original identity, as far as cell type goes.
B)If all of the cells from a given individual reaggregated to form the same individual, but if each cell had a different identity than it had before disaggregation.
C)If cells from different original individuals reaggregated together to form new individual organisms.
D)If cells from different original individuals reaggregated together to form new species.

Question 79

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.
Which of these, if discovered among cycliophorans, would cause the most confusion concerning our current understanding of cycliophoran taxonomy?

A)if the ciliated feeding ring is a lophophore
B)if embryos are diploblastic
C)if the body cavity is actually a pseudocoelom
D)if the organisms show little apparent cephalization

Question 80

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.
Which of these features is least useful in assigning the phylum Cycliophora to a clade of animals?

A)having a true coelom as a body cavity
B)having a body symmetry that permits a U-shaped intestine
C)having embryos with spiral cleavage
D)lacking ecdysis (moulting)