Campbell’s Biology, 9e (Reece et al.)
Chapter 26 Phylogeny and the Tree of Life
This chapter includes two new sets of art/scenario questions, one pertaining to the classification of birds
and reptiles, the other pertaining to the possible replacement of the orders Artiodactyla and Cetacea with
a new one, the Cetartiodactyla.
Multiple-Choice Questions
1) The legless condition that is observed in several groups of extant reptiles is the result of
A) their common ancestor having been legless.
B) a shared adaptation to an arboreal (living in trees) lifestyle.
C) several instances of the legless condition arising independently of each other.
D) individual lizards adapting to a fossorial (living in burrows) lifestyle during their lifetimes.
2) The various taxonomic levels (namely, genera, classes, etc.) of the hierarchical classification system
differ from each other on the basis of
A) how widely the organisms assigned to each are distributed throughout the environment.
B) their inclusiveness.
C) the relative genome sizes of the organisms assigned to each.
D) morphological characters that are applicable to all organisms.
3) If organisms A, B, and C belong to the same class but to different orders and if organisms D, E, and F
belong to the same order but to different families, which of the following pairs of organisms would be
expected to show the greatest degree of structural homology?
A) A and B
B) A and C
C) B and D
D) C and F
E) D and F
4) Linnaeus was a “fixist” who believed that species remained fixed in the form in which they had been
created. Linnaeus would have been uncomfortable with
A) classifying organisms using the morphospecies concept.
B) the scientific discipline known as taxonomy.
C) phylogenies.
D) nested, ever-more inclusive categories of organisms.
E) a hierarchical classification scheme.
5) Which of the following is (are) problematic when the goal is to construct phylogenies that accurately
reflect evolutionary history?
A) polyphyletic taxa
B) paraphyletic taxa
C) monophyletic taxa
D) Two of the responses are correct.
6) Which individual would make the worst systematist? One who is uncomfortable with the
A) Linnaean system of classification.
B) notion of hypothetical phylogenies.
C) PhyloCode method of classification.
D) notion of permanent polytomies.
7) The term homoplasy is most applicable to which of the following features?
A) the legless condition found in various lineages of extant lizards
B) the five-digit condition of human hands and bat wings
C) the β hemoglobin genes of mice and of humans
D) the fur that covers Australian moles and North American moles
E) the bones of bat forelimbs and the bones of bird forelimbs
8) If, someday, an archaean cell is discovered whose rRNA sequence is more similar to that of humans
than the sequence of mouse rRNA is to that of humans, the best explanation for this apparent
discrepancy would be
A) homology.
B) homoplasy.
C) common ancestry.
D) retro-evolution by humans.
E) coevolution of humans and that archaean.
9) The best classification system is that which most closely
A) unites organisms that possess similar morphologies.
B) conforms to traditional, Linnaean taxonomic practices.
C) reflects evolutionary history.
D) reflects the basic separation of prokaryotes from eukaryotes.
10) Which of the following pairs are the best examples of homologous structures?
A) bones in the bat wing and bones in the human forelimb
B) owl wing and hornet wing
C) bat wing and bird wing
D) eyelessness in the Australian mole and eyelessness in the North American mole
11) Some molecular data place the giant panda in the bear family (Ursidae) but place the lesser panda in
the raccoon family (Procyonidae). Consequently, the morphological similarities of these two species are
probably due to
A) inheritance of acquired characteristics.
B) sexual selection.
C) inheritance of shared derived characters.
D) possession of analogous structures.
E) possession of shared primitive characters.
12) The importance of computers and of computer software to modern cladistics is most closely linked
to advances in
A) light microscopy.
B) radiometric dating.
C) fossil discovery techniques.
D) Linnaean classification.
E) molecular genetics.
13) Which mutation should least require realignment of homologous regions of a gene that is common
to several related species?
A) three-base insertion
B) one-base substitution
C) four-base insertion
D) one-base deletion
E) three-base deletion
14) The common ancestors of birds and mammals were very early (stem) reptiles, which almost
certainly possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are
alike in having four-chambered hearts (two atria, two ventricles). The four-chambered hearts of birds
and mammals are best described as
A) structural homologies.
B) vestiges.
C) homoplasies.
D) the result of shared ancestry.
E) molecular homologies.
15) Which of the following is true of all horizontally oriented phylogenetic trees, where time advances
to the right?
A) Each branch point represents a point in absolute time.
B) Organisms represented at the base of such trees are descendants of those represented at higher levels.
C) The fewer branch points that occur between two taxa, the more divergent their DNA sequences
should be.
D) The common ancestor represented by the rightmost branch point existed more recently in time than
the common ancestors represented at branch points located to the left.
E) The more branch points there are, the fewer taxa are likely to be represented.
16) When using a cladistic approach to systematics, which of the following is considered most important
for classification?
A) shared primitive characters
B) analogous primitive characters
C) shared derived characters
D) the number of homoplasies
E) overall phenotypic similarity
17) Cladograms (a type of phylogenetic tree) constructed from evidence from molecular systematics are
based on similarities in
A) morphology.
B) the pattern of embryological development.
C) biochemical pathways.
D) habitat and lifestyle choices.
E) mutations to homologous genes.
18) There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their
mouths. If true, then what can be properly said of hair?
A) It is a shared derived character of mammals, even if cynodonts continue to be classified as reptiles.
B) It is a shared derived character of the amniote clade, and not of the mammal clade.
C) It is a shared ancestral character of the amniote clade, but only if cynodonts are reclassified as
mammals.
D) It is a shared derived character of the mammals, but only if cynodonts are reclassified as mammals.
19) A researcher wants to determine the genetic relatedness of several breeds of dog (Canis lupus
familiaris). The researcher should compare homologous sequences of this type of
biochemical ________ which can be described as ________.
A) fatty acids; highly conserved
B) lipids; poorly conserved
C) proteins; highly conserved
D) amino acids; highly conserved
E) nucleic acids, poorly conserved
20) Concerning growth in genome size over evolutionary time, which of these is least associated with
the others?
A) orthologous genes
B) gene duplications
C) paralogous genes
D) gene families
21) Nucleic acid sequences that undergo few changes over the course of evolutionary time are said to be
conserved. Conserved sequences of nucleic acids
A) are found in the most crucial portions of proteins.
B) include all mitochondrial DNA.
C) are abundant in ribosomes.
D) are proportionately more common in eukaryotic introns than in eukaryotic exons.
E) comprise a larger proportion of pre-mRNA (immature mRNA)
than of mature mRNA.
22) Species that are not closely related and that do not share many anatomical similarities can still be
placed together on the same phylogenetic tree by comparing their
A) plasmids.
B) mitochondrial genomes.
C) homologous genes that are poorly conserved.
D) homologous genes that are highly conserved.
23) Which kind of DNA should provide the best molecular clock for determining the evolutionary
relatedness of several species whose common ancestor became extinct billions of years ago?
A) that coding for ribosomal RNA
B) intronic DNA belonging to a gene whose product performs a crucial function
C) paralogous DNA that has lost its function (i.e., no longer codes for functional gene product)
D) mitochondrial DNA
E) exonic DNA that codes for a noncrucial part of a polypeptide
24) A phylogenetic tree constructed using sequence differences in mitochondrial DNA would be most
valid for discerning the evolutionary relatedness of
A) archaeans and bacteria.
B) fungi and animals.
C) chimpanzees and humans.
D) sharks and dolphins.
E) mosses and ferns.
25) The lakes of northern Minnesota are home to many similar species of damselflies of the genus
Enallagma that have apparently undergone speciation from ancestral stock since the last glacial retreat
about 10,000 years ago. Sequencing which of the following would probably be most useful in sorting
out evolutionary relationships among these closely related species?
A) nuclear DNA
B) mitochondrial DNA
C) small nuclear RNA
D) ribosomal RNA
E) amino acids in proteins
26) Which statement represents the best explanation for the observation that the nuclear DNA of wolves
and domestic dogs has a very high degree of sequence homology?
A) Dogs and wolves have very similar morphologies.
B) Dogs and wolves belong to the same order.
C) Dogs and wolves are both members of the order Carnivora.
D) Dogs and wolves shared a common ancestor very recently.
27) The reason that paralogous genes can diverge from each other within the same gene pool, whereas
orthologous genes diverge only after gene pools are isolated from each other, is that
A) having multiple copies of genes is essential for the occurrence of sympatric speciation in the wild.
B) paralogous genes can occur only in diploid species; thus, they are absent from most prokaryotes.
C) polyploidy is a necessary precondition for the occurrence of sympatric speciation in the wild.
D) having an extra copy of a gene permits modifications to the copy without loss of the original gene
product.
28) Paralogous genes that have lost the function of coding for any functional gene product are known as
“pseudogenes.” Which of these is a valid prediction regarding the fate of pseudogenes over evolutionary
time?
A) They will be preserved by natural selection.
B) They will be highly conserved.
C) They will ultimately regain their original function.
D) They will be transformed into orthologous genes.
E) They will have relatively high mutation rates.
29) The most important feature that permits a gene to act as a molecular clock is
A) having a large number of base pairs.
B) having a larger proportion of exonic DNA than of intronic DNA.
C) having a reliable average rate of mutation.
D) its recent origin by a gene-duplication event.
E) its being acted upon by natural selection.
30) Neutral theory proposes that
A) molecular clocks are more reliable when the surrounding pH is close to 7.0.
B) most mutations of highly conserved DNA sequences should have no functional effect.
C) DNA is less susceptible to mutation when it codes for amino acid sequences whose side groups (or R
groups) have a neutral pH.
D) DNA is less susceptible to mutation when it codes for amino acid sequences whose side groups (or R
groups) have a neutral electrical charge.
E) a significant proportion of mutations are not acted upon by natural selection.
31) When it acts upon a gene, which of the following processes consequently makes that gene an
accurate molecular clock?
A) transcription
B) directional natural selection
C) mutation
D) proofreading
E) reverse transcription
32) Which of these would, if it had acted upon a gene, prevent this gene from acting as a reliable
molecular clock?
A) neutral mutations
B) genetic drift
C) mutations within introns
D) natural selection
E) most substitution mutations involving an exonic codon’s third position
33) What kind of evidence has recently made it necessary to assign the prokaryotes to either of two
different domains, rather than assigning all prokaryotes to the same kingdom?
A) molecular
B) behavioral
C) nutritional
D) anatomical
E) ecological
34) What important criterion was used in the late 1960s to distinguish between the three multicellular
eukaryotic kingdoms of the five-kingdom classification system?
A) the number of cells present in individual organisms
B) the geological stratum in which fossils first appear
C) the nutritional modes they employ
D) the biogeographic province where each first appears
E) the features of their embryos
35) Members of which kingdom have cell walls and are all heterotrophic?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera
36) Which kingdom has been replaced with two domains?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera
37) Which eukaryotic kingdom is polyphyletic, and therefore unacceptable, based on cladistics?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera
38) Which eukaryotic kingdom includes members that are the result of endosymbioses that included an
ancient proteobacterium and an ancient cyanobacterium?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera
39) A large proportion of archaeans are extremophiles, so called because they inhabit extreme
environments with high acidity, salinity, and/or temperature. Such environments are thought to have
been much more common on the primitive Earth. Thus, modern extremophiles survive only in places
that their ancestors became adapted to long ago. Which of the following is, consequently, a valid
statement about modern extremophiles, assuming that their habitats have remained relatively
unchanged?
A) Among themselves, they should share relatively few ancestral traits, especially those that enabled
ancestral forms to adapt to extreme conditions.
B) On a phylogenetic tree whose branch lengths are proportional to the amount of genetic change, the
branches of the extremophiles should be shorter than the non-extremophilic archaeans.
C) They should contain genes that originated in eukaryotes that are the hosts for numerous species of
bacteria.
D) They should currently be undergoing a high level of horizontal gene transfer with non-extremophilic
archaeans.
Art Questions
Use Figure 26.1 to answer the following questions.
Figure 26.1
40) Which extinct species should be the best candidate to serve as the outgroup for the clade whose
common ancestor occurs at position 2 in Figure 26.1?
A) A
B) B
C) C
D) D
E) E
41) If Figure 26.1 is an accurate depiction of relatedness, then which of the following should be correct?
1. The entire tree is based on maximum parsimony.
2. If all species depicted here make up a taxon, this taxon is monophyletic.
3. The last common ancestor of species B and C occurred more recently than the last common
ancestor of species D and E.
4. Species A is the direct ancestor of both species B and species C.
5. The species present at position 3 is ancestral to C, D, and E.
A) 1 and 3
B) 3 and 4
C) 2, 3, and 4
D) 1, 2, and 3
Traditionally, whales and hippopotamuses have been classified in different orders, the Cetacea and the
Artiodactyla, respectively. Recent molecular evidence, however, indicates that the whales’ closest living
relatives are the hippos. This has caused some zoologists to lump the two orders together into a single
clade, the Cetartiodactyla. There is no consensus on whether the Cetartiodactyla should be accorded
order status or superorder status. This is because it remains unclear whether the whale lineage diverged
from the lineage leading to the hippos before or after the other members of the order Artiodactyla (pigs,
camels, etc.) diverged (see Figure 26.2).
Figure 26.2
Figure 26.2 contrasts the “Within the artiodactyls” origin of the whale lineage with the “Without the
artiodactyls” origin of the whale lineage.
42) Placing whales and hippos in the same clade means
A) that these organisms are phenotypically more similar to each other than to any others shown on the
trees in Figure 26.2.
B) that their morphological similarities are probably homoplasies.
C) that they had a common ancestor.
D) that all three of the responses are correct.
E) that two of the responses are correct.
43) 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 order Artiodactyla?
A) It becomes monophyletic.
B) It becomes paraphyletic.
C) It becomes polyphyletic.
D) It is incorporated into the order Cetacea.