Use the following information to answer the question(s) below.
Nudibranchs, a type of predatory sea slug, can have various protuberances (that is, extensions)
on their dorsal surfaces. Rhinophores are paired structures, located close to the head, which bear
many chemoreceptors. Dorsal plummules, usually located posteriorly, perform respiratory gas
exchange. Cerata usually cover much of the dorsal surface and contain nematocysts at their tips.
38) If nudibranch rhinophores are located at the anterior ends of these sea slugs, then they
contribute to the sea slugs’ _____.
A) segmentation
B) lack of torsion
C) cephalization
D) identity as lophotrochozoans
1. Protostomes invade terrestrial environments.
2. Cambrian explosion occurs.
3. Deuterostomes invade terrestrial environments.
4. Vertebrates become top predators in the seas.
A) 2 → 1 → 4 → 3
B) 2 → 4 → 1 → 3
C) 2 → 3 → 1 → 4
D) 2 → 1 → 3 → 4
1. tetrapods
2. vertebrates
3. deuterostomes
4. amniotes
5. bilaterians
A) 5 → 3 → 2 → 1 → 4
B) 5 → 3 → 4 → 2 → 1
C) 3 → 5 → 4 → 2 → 1
D) 3 → 5 → 2 → 1 → 4
41) The most ancient branch point in animal phylogeny is the characteristic of having _____.
A) radial or bilateral symmetry
B) diploblastic or triploblastic embryos
C) true tissues or no tissues
D) a body cavity or no body cavity
42) 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?
A) It is segmented.
B) It is triploblastic.
C) It has a coelom.
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.
43) 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 3
15
44) The common ancestor of the protostomes had a coelom. What does this suggest?
A) All lophotrochozoans have a coelom.
B) There are no pseudocoelomates within the protostomes.
C) There are no acoelomates within the protostomes.
D) The body cavity evolved before the lophophore.
16
A: Morphological phylogeny.
17
B: Molecular phylogeny.
45) 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 a monophyletic clade 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.
18
46) The Hox genes came to regulate each of the following. From earliest to most recent, in what
sequence did these events evolve?
1. identity and position of paired appendages in protostome embryos
2. anterior-posterior orientation of segments in protostome embryos
3. positioning of tentacles in cnidarians
4. anterior-posterior orientation in vertebrate embryos
A) 4 → 1 → 3 → 2
B) 4 → 2 → 1 → 3
C) 3 → 2 → 1 → 4
47) 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) the 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”
48) Some researchers claim that sponge genomes have homeotic genes, but no Hox genes. If
true, this finding would _____.
A) mean that sponges must no longer be classified as animals
B) confirm the identity of sponges as “basal animals”
C) mean that extinct sponges must have been the last common ancestor of animals and fungi
D) require sponges to be reclassified as choanoflagellates
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.
49) 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
50) The feeding stage of cycliophorans _____.
1. is autotrophic
2. is sessile
3. captures food in a manner similar to that of animals with lophophores
4. shows radial symmetry
A) 1 and 2
B) 1 and 3
C) 2 and 4
D) 1, 2, and 3
20
51) Which morphological trait evolved more than once in animals, according to the phylogeny
based on DNA sequence data found in the figure above?
A) coelom
B) bilateral symmetry
C) segmentation
D) protostome development
52) Why might researchers choose to use molecular data (such as ribosomal RNA sequences)
rather than morphological data to study the evolutionary history of animals?
A) Molecular data can be gathered in the lab, while morphological data must be gathered in the
field.
B) Sequence data can be gathered faster than morphological data, and morphological data
provides a different perspective.
C) Morphological changes usually do not result from molecular changes.
D) Some phyla vary too widely in morphological characteristics to be classified accurately.
53) If in the future the current molecular evidence regarding animal origins is further
substantiated, what will be true of any contrary evidence regarding the origin of animals derived
from the fossil record?
A) The contrary fossil evidence will be seen as a hoax.
B) The fossil evidence will be understood to have been interpreted incorrectly 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.
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.
54) Basing your inferences on information in the paragraph above, to which clade(s) should
cycliophorans belong?
1. Eumetazoa
2. Deuterostomia
3. Bilateria
4. Ecdysozoa
5. Lophotrochozoa
A) 1 and 3
B) 1, 3, and 5
C) 2, 3, and 4
D) 2, 3, and 5
Use the following table to answer the question(s) below.
Proposed Number of Hox Genes in Various Extant and Extinct Animals
Last Common
Ancestor
of Bilateria
Last Common
Ancestor of Insects
and Vertebrates
Ancestral
Vertebrates
Mammals
4
7
14
38-40
55) What conclusion is apparent from the data in the table above?
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) The expansion in number of Hox genes throughout vertebrate evolution cannot be explained
merely by three duplications of the ancestral vertebrate Hox cluster.
D) Extant insects all have seven Hox genes.
56) All things being equal, which of these is the most parsimonious explanation for the change in
the number of Hox genes from the last common ancestor of insects and vertebrates to ancestral
vertebrates, as shown in the table above?
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.
57) 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 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
58) In the experiment outlined in the figure above, what would you expect to happen if
researchers supplied an enzyme that blocked the expression of the Dll gene?
A) The embryo would have appendages in abnormal locations.
B) The origins of the embryo’s appendages would fluoresce.
C) The developing embryo would have no appendages.
D) The embryo’s appendages would be shorter than usual.
59) Dll is a gene known to direct limb development in the fruit fly. Researchers studying this
gene have found that it is also expressed in developing appendages in animals from many other
phyla, supporting the hypothesis that all animal appendages may be homologous. However,
suppose researchers looking at Dll activity had instead found the results shown in the figure
above. These results suggest instead that _____.
A) Dll is not actually involved in appendage development
B) appendages evolved separately in protostomes and deuterostomes
C) appendages coevolved with segmentation
D) all animal appendages are homologous
60) Which of the following statements concerning animal taxonomy is (are) true?
1. Animals are more closely related to plants than to fungi.
2. All animal clades based on body plan have been found to be incorrect.
3. Kingdom Animalia is monophyletic.
4. Animals only reproduce sexually.
5. Animals are thought to have evolved from flagellated protists similar to modern
choanoflagellates.
A) 1 and 2
B) 3 and 5
C) 3, 4, and 5
D) 2 and 4