If it turns out that the whale lineage diverged from the lineage leading to hippos after the
divergence of the lineage leading to the pigs and other artiodactyls, and if the whales continue to
be classified in the order Cetacea, then what becomes true of the taxon Cetartiodactyla?
A) It should be considered as one monophyletic superorder.
B) It should be considered a superorder that consists of two monophyletic orders.
C) It should be established as a paraphyletic order.
D) It should be thrown out or modified by taxonomists if classification is to reflect evolutionary
history.

It should be considered as one monophyletic superorder.

One morphological feature of modern cetaceans is a vestigial pelvic girdle. If it is determined
that cetacean lineage diverged from the artiodactyls' lineage after the divergence of pigs and
other artiodactyla, then what should be true of the vestigial pelvic girdle of cetaceans?
A) It should be considered a shared ancestral character of the cetartiodactyls.
B) It should be considered a shared derived character of the cetartiodactyls.
C) It should be considered a shared ancestral character of the cetaceans.
D) It should be considered a shared derived character of the cetaceans.

It should be considered a shared derived character of the cetaceans.

If cetaceans are determined to have diverged from the lineage leading to the artiodactyls
before the divergence of lineages leading to the modern artiodactyls (including hippos), then the
cetaceans can be considered
1. a sister order to the order Artiodactyla.
2. an ingroup of the order Artiodactyla.
3. the common ancestor of the order Artiodactyla.
A) 1 only
B) 3 only
C) 1 and 2
D) 1 and 3
E) 2 and 3

1 only

It was once thought that cetaceans had evolved from an extinct group of mammals called the
mesonychids. If, in the future, it is determined that some organisms currently classified as
cetaceans did actually evolve from mesonychids, whereas other cetaceans evolved from
artiodactyl stock, then what will be true of the order Cetacea?
A) It will be paraphyletic.
B) It will be polyphyletic.
C) It will need to be modified if classification is to reflect evolutionary history.
D) A and C
E) B and C

A and C

If the early history of life on Earth is accurately depicted by Figure 20.3, then which
statement is least in agreement with the hypothesis proposed by this tree?
A) The last universal common ancestor of all extant species is better described as a community
of organisms, rather than an individual species.
B) The origin of the three domains appears as a polytomy.
C) Archaean genomes should contain genes that originated in bacteria, and vice versa.
D) Eukaryotes are more closely related to archaeans than to bacteria.

Eukaryotes are more closely related to archaeans than to bacteria.

Which of these processes can be included among those responsible for the horizontal
components of Figure 20.3?
A) endosymbiosis
B) mitosis
C) binary fission
D) point mutations
E) S phase of the cell cycle

endosymbiosis

Which portion of Figure 20.3 may ultimately be better depicted as a "ring"?
A) the bacterial lineage
B) the archaean lineage
C) the eukaryotic lineage
D) the trunk of the tree
E) the part corresponding to the first living cell on Earth

the trunk of the tree

The great apes comprise the family Hominidae, whereas the lesser apes comprise the family
Hylobatidae. If the extant organisms on the far right side of Figure 20.4 comprise the next-most
exclusive (i.e., specific) taxon, then they comprise different
A) subspecies.
B) species.
C) genuses.
D) genera.
E) orders.

genera.

Together, the lesser apes and great apes shared a common ancestor most recently with other
members of their
A) order.
B) class.
C) subclass.
D) subfamily.
E) family.

order.

Assuming chimps and gorillas are humans' closest relatives, removing humans from the great
ape clade and placing them in a different clade has the effect of making the phylogenetic tree of
the great apes
A) polyphyletic.
B) paraphyletic.
C) monophyletic.
D) conform with Linnaeus's view of great ape phylogeny.

paraphyletic.

From Figure 20.4, which other event occurred closest in time to the divergence of gorillas
from the lineage that led to humans and chimps?
A) the divergence of chimps and humans
B) the divergence of Dryopithecus and Ouranopithecus
C) the divergence of gibbons and siamangs
D) could be either the divergence of chimps and humans OR of Dryopithecus and
Ouranopithecus
E) could be either the divergence of chimps and humans OR of gibbons and siamangs

could be either the divergence of chimps and humans OR of gibbons and siamangs

Which of the following is the best explanation for the high degree of sequence homology
observed in Exon I among these five species?
A) It is the most-upstream exon of this gene.
B) Due to alternative gene splicing, this exon is often treated as an intron.
C) It codes for a polypeptide domain that has a crucial function.
D) These five species must actually constitute a single species.
E) This exon is rich in G-C base pairs; thus, it is more stable.

It codes for a polypeptide domain that has a crucial function.

Regarding these sequence homology data, the principle of maximum parsimony would be
applicable in
A) distinguishing introns from exons.
B) determining degree of sequence homology.
C) selecting appropriate genes for comparison among species.
D) inferring evolutionary relatedness from the number of sequence differences.

inferring evolutionary relatedness from the number of sequence differences.

20) Which of these four gene parts should allow the construction of the most accurate
phylogenetic tree, assuming that this is the only part of the gene that has acted as a reliable
molecular clock?
A) Intron I
B) Exon I
C) Intron VI
D) Exon V

Intron VI