Question 1

Based on this tree, which statement is correct?

Accepted Answer

A)  The human lineage is a basal taxon. 
B)  Salamanders are a sister group to the group containing lizards, goats, and humans. 
C)  Salamanders are as closely related to lizards as to humans. 
D)  Goats are more closely related to salamanders than to humans.

Question 2

Use the figure to answer the following question.

If the figure above is an accurate depiction of relatedness, then which of the following should be an accurate statement?

Accepted Answer

A)  The entire tree is based on minimum parsimony. 
B)  If all species depicted here make up a taxon, this taxon is paraphyletic. 
C)  The last common ancestor of species B and C occurred more recently than the last common ancestor of species D and E. 
D)  Species A is the direct ancestor of both species B and species C.

Question 3

The various taxonomic levels (for example, phyla, genera, classes)of the hierarchical classification system differ from each other on the basis of ________.

Accepted Answer

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

Question 4

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 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?

Accepted Answer

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.

Question 5

Which eukaryotic kingdom includes members that are the result of endosymbioses that included an ancient aerobic bacterium and an ancient cyanobacterium?

Accepted Answer

A)  Plantae 
B)  Fungi 
C)  Animalia 
D)  Protista

Question 6

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.
Cyanobacteria were once called blue-green algae because they are photosynthetic. According to the phylogeny shown, the cyanobacteria are more closely related to gram-positive bacteria than to ________.

Accepted Answer

A)  proteobacteria 
B)  green algae 
C)  euglenozoans 
D)  crenarcheotes

Question 7

Which of the following statements is accurate with regard to a phylogeny, as represented by a phylogenetic tree?

Accepted Answer

A)  Descendant groups (branches) from the same node likely share many derived characters. 
B)  A monophyletic group can be properly based on convergent features. 
C)  The ancestral group often has all the derived characters of the descendant species. 
D)  Shared ancestral characters are excellent traits to use in developing a phylogeny.

Question 8

The kingdom Monera was dismantled because of which of the following reasons?

Accepted Answer

A)  Some Monera contained nuclei in their cells. 
B)  The Monera, as originally constituted, contained both plants and animals. 
C)  The Monera, as originally constituted, was monophyletic. 
D)  Some, but not all, of the organisms in Monera contained DNA sequences that were similar to those of eukaryotes.

Question 9

The lakes of northern Minnesota are home to many similar species of damselflies of the genus Enallagma. These species have apparently undergone speciation from ancestral stock since the last glacial retreat about 10 thousand years ago. Sequencing which of the following would probably be most useful in sorting out evolutionary relationships among these closely related species?

Accepted Answer

A)  conserved regions of nuclear DNA 
B)  mitochondrial DNA 
C)  amino acids in proteins 
D)  ribosomal RNA

Question 10

There is some evidence that reptiles called cynodonts may have had whisker-like hairs around their mouths. If true, then hair is a shared ________.

Accepted Answer

A)  derived character of mammals, even if cynodonts continue to be classified as reptiles 
B)  derived character of all vertebrates and not of the mammal clade 
C)  ancestral character of the all vertebrates, but only if cynodonts are reclassified as mammals 
D)  derived character of mammals, but only if cynodonts are reclassified as mammals

Question 11

Which of the following items is most likely to form a simple linear relationship with the number of gene-duplication events, when placed as the label on the vertical axis of the following graph?

Accepted Answer

A)  number of mitochondria 
B)  number of cells/organism 
C)  genome size 
D)  phenotypic complexity

Question 12

The most important feature that permits a gene to act as a molecular clock is ________.

Accepted Answer

A)  a large number of base pairs 
B)  being acted upon by natural selection 
C)  a reliable average rate of mutation 
D)  a recent origin by a gene-duplication event

Question 13

Which of the following statements about horizontal gene transfer is accurate?

Accepted Answer

A)  Horizontal gene transfer was quite common in the early stages of evolution of life on Earth. 
B)  Horizontal gene transfer among organisms does not occur today. 
C)  Horizontal gene transfer moves only genes that play a role in metabolism. 
D)  Horizontal gene transfer occurs only among closely related organisms.

Question 14

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 ________.

Accepted Answer

A)  homology 
B)  convergent evolution 
C)  common ancestry 
D)  retro-evolution by humans

Question 15

Based on the tree below, which statement is not correct?

Accepted Answer

A)  Goats and humans form a sister group. 
B)  Salamanders are a sister group to the group containing lizards, goats, and humans. 
C)  Salamanders are as closely related to goats as to humans. 
D)  Lizards are more closely related to salamanders than to humans.

Question 16

Use the following information to answer the question.
Giardia intestinalis can cause disease in several different mammalian species, including humans. Giardia organisms (G. intestinalis)that infect humans are similar morphologically to those that infect other mammals, thus they have been considered a single species. However, G. intestinalis has been divided into different subgroups based on their host and a few other characteristics.
In 1999, a DNA sequence comparison study tested the hypothesis that these subgroups actually constitute different species. The following phylogenetic tree was constructed from the sequence comparison of rRNA from several subgroups of G. intestinalis and a few other morphologically distinct species of Giardia. The researchers concluded that the subgroups of Giardia are sufficiently different from one another genetically that they could be considered different species. (T. Monis, et al. 1999. Molecular systematics of the parasitic protozoan Giardia intestinalis. Mol. Biol. Evol. 16[9]:1135-44.)

Which of the following changes would a modern systematist be most likely to make after learning of the results of the rRNA analyses?

Accepted Answer

A)  continue to keep subgroups A-D as members of the species G. intestinalis 
B)  break the species G. intestinalis into four separate species, A, B, C, and D 
C)  combine subgroup D and G. microti into one species 
D)  combine all the subgroups of G. intestinalis (A-
D)  and G. microti to make one species

Question 17

Three living species X, Y, and Z share a common ancestor T, as do extinct species U and V. A grouping that consists of species T, X, Y, and Z (but not U or V)makes up

Accepted Answer

A)  a monophyletic taxon. 
B)  an ingroup, with species U as the outgroup. 
C)  a paraphyletic group. 
D)  a polyphyletic group.

Question 18

A phylogenetic tree is shown for the three domains of life (Eukarya, Archaea, and Bacteria). The tree branches in two directions from the first point, labeled Common ancestor of all life. One branch leads in the direction of Eukarya and Archaea, and the other branch leads to Bacteria. The branch leading to Eukarya and Archaea divide, one branch leading to each domain. The branch leading to Eukarya divides into four branches. One leads to Euglenozoans, and the other three lead to branching points. The first leads to Forams in one direction, and another branching point in the other that leads to Diatoms and Ciliates. The second branching point leads to Red algae in one direction, and a branching point that leads to green algae and land plants in the other direction. The third branching point leads to amoebas in one direction, and a branching point that leads to fungi and animals in the other direction. Land plants, Fungi and Animals are all highlighted.
Examine the figure. If you were a graduate student trying to develop a thesis project that would resolve polytomies, which of the following groups would you study?

Accepted Answer

A)  animals and fungi 
B)  euglenozoans, euryarcheotes, and gram-positive bacteria 
C)  forams, red algae, and amoebas 
D)  red algae, green algae, and cyanobacteria

Question 19

In Figure 26.4, which similarly inclusive taxon is represented as descending from the same common ancestor as Canidae?

Accepted Answer

A)  Felidae 
B)  Mustelidae 
C)  Carnivora 
D)  Lutra

Question 20

Which of the following is (are)problematic when the goal is to construct phylogenies that accurately reflect evolutionary history?

Accepted Answer

A)  polyphyletic taxa 
B)  paraphyletic taxa 
C)  monophyletic taxa 
D)  polyphyletic taxa and paraphyletic taxa

Exam 26: Phylogeny and the Tree of Life