26.6 Our understanding of the tree of life continues to change based on new data

Question 1

70) Which process hinders clarification of the deepest branchings in a phylogenetic tree that
depicts the origins of the three domains?
A) binary fission
B) mitosis
C) meiosis
D) horizontal gene transfer
E) gene duplication

Answer 1

D) horizontal gene transfer

Question 2

71) 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

Answer 2

A) molecular

Question 3

72) 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

Answer 3

C) the nutritional modes they employ

Question 4

73) Which is an obsolete kingdom that includes prokaryotic organisms?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer 4

E) Monera

Question 5

74) Members of which kingdom have cell walls and are all heterotrophic?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer 5

B) Fungi

Question 6

75) Which kingdom has been replaced with two domains?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer 6

E) Monera

Question 7

76) Which eukaryotic kingdom is polyphyletic and therefore not acceptable, based on
cladistics?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Answer 7

D) Protista

Question 8

77) 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

Answer 8

A) Plantae

Question 9

78) The human nuclear genome includes hundreds of genes that are orthologs of bacterial
genes, and hundreds of other genes that are orthologs of archaean genes. This finding can
be explained by proposing that
A) neither archaea nor bacteria contain paralogous genes.
B) the eukaryotic lineage leading to humans involved at least one fusion of an ancient bacterium with an ancient archaean.
C) the infection of humans by bacteriophage introduced prokaryotic genes into the human genome.
D) horizontal gene transfer did not occur to any significant extent among the prokaryotic ancestors of humans.

Answer 9

B) the eukaryotic lineage leading to humans involved at least one fusion of an ancient bacterium with an ancient archaean.

Question 10

79) If the early history of life on Earth is accurately depicted by this phylogenetic tree, 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.

Answer 10

D) Eukaryotes are more closely related to archaeans than to bacteria.

Question 11

80) Which process is observed in prokaryotes and is responsible for the vertical components of
the various bacterial and archaean lineages?
A) mitosis
B) meiosis
C) sexual reproduction
D) binary fission

Answer 11

D) binary fission

Question 12

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

Answer 12

A) endosymbiosis

Question 13

82) Which portion of this tree may ultimately be better depicted as a ʺringʺ?
A) the bacterial lineage
B) the archaean lineage
C) the eukaryotic lineage
D) the weblike part near the base of the tree
E) the part corresponding to the first living cell on Earth

Answer 13

D) the weblike part near the base of the tree

Question 14

83) A large proportion of archaeans are ʺextremophiles,ʺ so called because they inhabit extreme
environments with high acidity and/or high 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 these 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 amount of genetic change, the branches of the extremophiles should be shorter, relative to branches of 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.

Answer 14

B) On a phylogenetic tree whose branch lengths are proportional to amount of genetic change, the branches of the extremophiles should be shorter, relative to branches of the non-extremophilic archaeans.

Question 15

1) In Figure 26.4 from your textbook, which similarly inclusive taxon descended from the
same common ancestor as Canidae?
A) Felidae
B) Mustelidae
C) Carnivora
D) Canis
E) Lutra

Answer 15

B) Mustelidae

Question 16

2) Three living species X, Y, and Z share a common ancestor T, as do extinct species U and V.
A grouping that includes species T, X, Y, and Z makes up
A) a valid taxon.
B) a monophyletic clade.
C) an ingroup, with species U as the outgroup.
D) a paraphyletic grouping.
E) a polyphyletic grouping.

Answer 16

D) a paraphyletic grouping.

Question 17

3) In a comparison of birds with mammals, having four appendages is
A) a shared ancestral character.
B) a shared derived character.
C) a character useful for distinguishing birds from mammals.
D) an example of analogy rather than homology.
E) a character useful for sorting bird species.

Answer 17

A) a shared ancestral character.

Question 18

4) If you were using cladistics to build a phylogenetic tree of cats, which of the following
would be the best outgroup?
A) lion
B) domestic cat
C) wolf
D) leopard
E) tiger

Answer 18

C) wolf

Question 19

5) The relative lengths of the amphibian and mouse branches in the phylogeny in Figure 26.12
in your textbook indicate that
A) amphibians evolved before mice.
B) mice evolved before amphibians.
C) the genes of amphibians and mice have only coincidental homoplasies.
D) the homologous gene has evolved more slowly in mice.
E) the homologous gene has evolved more rapidly in mice.

Answer 19

D) the homologous gene has evolved more slowly in mice.

Question 20

7) To apply parsimony to constructing a phylogenetic tree,
A) choose the tree that assumes all evolutionary changes are equally probable.
B) choose the tree in which the branch points are based on as many shared derived characters as possible.
C) base phylogenetic trees only on the fossil record, as this provides the simplest explanation for evolution.
D) choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology.
E) choose the tree with the fewest branch points.

Answer 20

D) choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology.