Chapter 32 - Animal Diversity

Question 1

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 1

B) ingesting it.

Question 2

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 favors 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

Answer 2

B) changes in the homeobox genes governing early development

Question 3

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.

Answer 3

C) nervous conduction and muscular movement

Question 4

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

Answer 4

D) presence of Hox genes

Question 5

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

Answer 5

D) 3 → 2 → 1 → 4

Question 6

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.

Answer 6

A) we could not clone a larva from the somatic cells of such an adult insect.

Question 7

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.

Answer 7

E) flagellated protist.

Question 8

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

Answer 8

E) increased incidence of hard parts in the fossil record

Question 9

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

Answer 9

D) gene duplication

Question 10

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.

Answer 10

C) adaptive radiation.

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

Answer 11

C) 2 → 4 → 1 → 3

Question 12

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

Answer 12

B) 5 → 3 → 2 → 1 → 4

Question 13

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.

Answer 13

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

Question 14

An adult animal that possesses bilateral symmetry is most certainly also:

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

Answer 14

A) triploblastic.

Question 15

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.

Answer 15

C) archenteron.

Question 16

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

Answer 16

B) collagen genes

Question 17

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

Answer 17

C) gastrulation

Question 18

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

Answer 18

B) cleavage

Question 19

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.

Answer 19

C) have a body cavity completely lined by mesodermal tissue, whereas pseudocoelomates do not.

Question 20

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.

Answer 20

D) Muscular activity of its digestive system distorts the body wall.

Question 21

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.

Answer 21

B) gastrulation.

Question 22

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.

Answer 22

A) archenteron.

Question 23

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

Answer 23

B) spiral and determinate cleavage, blastopore becomes mouth

Question 24

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

Answer 24

B) determinate cleavage

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 ```

Answer 25

D) determinate cleavage

Question 26

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. ```

Answer 26

D) true tissues or no tissues.

Question 27

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 ```

Answer 27

D) 3, 4, 2, 1

Question 28

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.

Answer 28

B) Some, but not all, grades reflect evolutionary relatedness.

Question 29

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.

Answer 29

B) hypothetical portrayals of evolutionary relationships.

Question 30

According to the evidence collected so far, the animal kingdom is: ``` A) monophyletic. B) paraphyletic. C) polyphyletic. D) euphyletic. E) multiphyletic. ```

Answer 30

A) monophyletic.

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. ```

Answer 31

B) metazoans.

Question 32

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

Answer 32

C) 3 and 5

Question 33

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.

Answer 33

B) The fossil evidence will be understood to have been incorrect because it is incomplete.

Question 34

What is true of the clade Ecdysozoa? A) It includes all animals that molt 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.

Answer 34

D) It includes all animals with genetic similarities that are shared with no other animals.

Question 35

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) molting and lack of molting ```

Answer 35

D) protostome and deuterostome

Question 36

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.

Answer 36

E) Two of the responses above are correct.

Question 37

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 ```

Answer 37

B) 1 and 4

Question 38

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.

Answer 38

C) confirm the identity of sponges as "basal animals."