Campbell Biology, 10e (Reece)
Chapter 32 An Overview of Animal Diversity
1) 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
2) Which of the following is (are) unique to animals?
A) the structural carbohydrate, chitin
B) nervous system signal conduction and muscular movement
C) heterotrophy
D) flagellated gametes
3) 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?
A) artificial selection of sexually immature forms of insects
B) changes in the homeobox genes governing early development
C) the evolution of meiosis
D) the origin of a brain
4) 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 three organisms and observe them in
detail, making the notations found in the figure above. Which organism would you classify as an
animal?
A) organism A
B) organism B
C) organism C
5) 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) ingesting it
C) consuming living, rather than dead, prey
D) using enzymes to digest their food
Use the following information to answer the question(s) 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.
6) Which of the following Tp traits is different from all other known animals?
A) Tp is multicellular.
B) Tp lacks muscle and nerve cells.
C) Tp has cilia.
D) Tp lacks cell walls.
7) What do animals ranging from corals to monkeys have in common?
A) a mouth and an anus
B) number of embryonic tissue layers
C) type of body symmetry
D) presence of Hox genes
8) 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 descendants of these adults do not include a larval stage
D) metamorphosis can no longer occur among the descendents of such adults
9) Which of the following would you classify as something other than an animal?
A) sponges
B) coral
C) jellyfish
D) choanoflagellates
10) The evolution of animal species has been prolific (the estimates go into the millions and tens
of millions). Much of this diversity is a result of the evolution of novel ways to _____.
A) reproduce
B) arrange cells into tissues
C) sense, feed, and move
D) form an embryo and establish a basic body plan
11) The last common ancestor of all animals was probably a _____.
A) unicellular chytrid
B) multicellular algae
C) multicellular fungus
D) flagellated protist
12) 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) embryos
13) 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 _____.
A) worm burrows
B) larger animals
C) organic material
D) hard parts
14) Which of the following genetic processes may be most helpful in accounting for the
Cambrian explosion?
A) binary fission
B) random segregation
C) gene duplication
D) chromosomal condensation
15) Whatever its ultimate cause(s), the Cambrian explosion is a prime example of _____.
A) mass extinction
B) evolutionary stasis
C) adaptive radiation
D) a large meteor impact
16) 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) vertebrates evolved from arthropods
D) arthropods have had more time to coevolve with land plants than have vertebrates
17) Which tissue type, or organ, is NOT correctly matched with its germ layer tissue?
A) nervous — mesoderm
B) muscular — mesoderm
C) stomach — endoderm
D) skin — ectoderm
18) 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 _____.
A) develops germ layers
B) exhibits spiral cleavage or radial cleavage
C) develops a blastopore
D) develops an archenteron
19) 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?
A) There is evidence of cephalization.
B) The animal is triploblastic.
C) The animal is clearly bilaterally symmetrical.
D) You see a mouth, but not an anus.
20) Which of the following is a feature of the tube-within-a-tube body plan in most animal
phyla?
A) The outer tube consists of a hard exoskeleton.
B) The outer tube consists of digestive organs.
C) The mouth and anus form the ends of the inner tube.
D) The two “tubes” are separated by tissue that comes from embryonic endoderm.
21) 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?
A) lining the straw
B) lining the space between the pipe and the straw
C) forming the outside of the pipe
D) forming the outside of the straw
22) Among protostomes, which morphological trait has shown the most variation?
A) type of symmetry (bilateral vs. radial vs. none)
B) type of body cavity (coelom vs. pseudocoelom vs. no coelom)
C) number of embryonic tissue types (diploblasty vs. triploblasty)
D) type of development (protostome vs. deuterostome)
23) What do all deuterostomes have in common?
A) Adults are bilaterally symmetrical.
B) Embryos have pharyngeal pouches that may or may not form gill slits.
C) All have a spinal column.
D) The pore (blastopore) formed during gastrulation becomes the anus.
24) 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
25) 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.
Use the following information to answer the question(s) 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.
26) On the basis of information in the paragraph above, 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 listed responses are correct.
Use the following information to answer the question(s) 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.
27) This embryo may potentially develop into a(n) _____.
A) turtle
B) earthworm
C) sea star
D) sea urchin
28) 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.
Use the following information to answer the question(s) 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 coelomates, do not molt (though their host does),
and their embryos undergo spiral cleavage.
29) 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 (molting)
Use the following figure and information to answer the question(s) below.
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.
30) We should expect the inner wall of the swim bladder to be lined with tissue that is derived
from _____.
A) ectoderm
B) endoderm
C) mesoderm
D) mesoglea
31) What was an early selective advantage of a coelom in animals? A coelom _____.
A) contributed to a hydrostatic skeleton, allowing greater range of motion
B) was a more efficient digestive system
C) allowed cephalization and the formation of a cerebral ganglion
D) allowed asexual and sexual reproduction
32) The protostome developmental sequence arose just once in evolutionary history, resulting in
two main subgroups—Lophotrochozoa and Ecdysozoa. What does this finding suggest?
A) These two subgroups have a common ancestor that was a deuterostome.
B) The protostomes are a polyphyletic group.
C) Division of these two groups occurred after the protostome developmental sequence
appeared.
D) The lophotrochozoans are monophyletic.
33) 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 and 4
B) 2 and 3
C) 2 and 4
D) 4 and 5
34) An organism that exhibits cephalization probably also _____.
A) is bilaterally symmetrical
B) has a coelom
C) is segmented
D) is diploblastic
35) 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?
A) The mosquito would develop a weakened exoskeleton that would make it vulnerable to
trauma.
B) The mosquito would have trouble digesting food, due to impaired gut function.
C) The mosquito would have trouble with respiration and circulation, due to impaired muscle
function.
D) The mosquito wouldn’t be affected at all.
Use the following information to answer the question(s) 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.
36) Tp’s body symmetry seems to be most like that of _____.
A) most sponges
B) cnidarians
C) worms
Use the following information to answer the question(s) 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 coelomates, do not molt (though their host does),
and their embryos undergo spiral cleavage.
37) 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