Chapter 26 HW: Phylogeny and the Tree of Life

Which of the following statements about descent with modification is false?

All similarities between organisms result from descent from a common ancestor.

Prokaryotic cells are found in the domain(s) _____.

Bacteria and Archaea

If organisms A, B, and C belong to the same class but to different orders and if organisms C, D, and E 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?

D and E

Why do researchers use rRNA in investigations of relationships between taxa that diverged hundreds of millions of years ago?

DNA coding for rRNA changes relatively slowly.

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

Descendant groups (branches) from the same node likely share many derived characters.

Which of the following statements is accurate, at least according to our present knowledge?

Genes from prokaryotes have been acquired by some eukaryotes; these genes can allow survival in extreme environments.

Which of these are homologous structures?

Ivy leaf and pine needle

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?

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.

Select the correct statement about phylogenetic trees.

Phylogenetic trees may expand quickly to maximum width and then narrow over time.

Which of the following statements best describes the rationale for applying the principle of maximum parsimony in constructing phylogenetic trees?

Similarity due to common ancestry should be more common than similarity due to convergent evolution.

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

Some, but not all, of the organisms in Monera contained DNA sequences that were similar to those of eukaryotes.

Which observation supports the position of eukaryotes at the convergence of the "ring of life"?

The nuclear genome of eukaryotes contains genes from archaeans and from bacteria.

Imagine that a phylogeny was developed for a group of mammals based on bone structure. Which of the following statements would be a reasonable prediction about a phylogeny for the same group of species based on similarities and differences in the structure of a particular enzyme?

The same phylogeny would be unlikely.

Phylogeny is the evolutionary history of related groups of organisms. Organisms are grouped into taxa based on homologous characteristics, shared traits that result from common ancestry. Which statement is true?

The term "monophyletic" refers to a taxon that includes an ancestral species and all of its descendants.

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

a paraphyletic group.

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

a reliable average rate of mutation

In a comparison of birds and mammals, having four limbs is _____.

a shared ancestral character

In a comparison of birds and mammals, having four limbs is

a shared ancestral character.

Molecular clocks are more reliable when ________.

a significant proportion of mutations are not acted upon by natural selection.

Suppose that two distantly related species live in similar environments and share a distinctive characteristic that facilitates survival in their environment but is not found in their immediate ancestors. Based on this information, this distinctive feature most likely represents

an analogous character.

Which of the following pairs are the best examples of homologous structures?

bones in the bat wing and bones in the human forelimb

A phylogenetic tree constructed using sequence differences in mitochondrial DNA would be most valid for discerning the evolutionary relatedness of _____.

chimpanzees and humans

To apply the principle of maximum parsimony to construction of a phylogenetic tree, ________.

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

To apply parsimony to constructing a phylogenetic tree,

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

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 ________.

convergent evolution

Some beetles and flies have antler-like structures on their heads, much like male deer. The existence of antlers in beetle, fly, and deer species with strong male-male competition is an example of ________.

convergent evolution

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

derived character of mammals, but only if cynodonts are reclassified as mammals

Animals that possess homologous structures probably _____.

evolved from the same ancestor

What process actually increases the number of genes in an organism's genome?

gene duplication

Systematists have used a wide variety of traits to reconstruct the phylogenies of particular groups of organisms. Which one of the following traits produces a good estimate of phylogeny?

gross morphological traits molecular traits behavioral traits biochemical traits

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 _____.

having an extra copy of a gene permits modifications to the copy without loss of the original gene product

Eukaryotes 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 _____.

homologous genes that are highly conserved

Which process occurred frequently in the early history of the three domains on Earth, and makes determining phylogenetic relationships of that time difficult?

horizontal gene transfer

The genome of an organism

includes all of the organism's DNA.

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?

mitochondrial DNA

The importance of computers and of computer software to modern systematics s is most closely linked to advances in ________.

molecular genetics

In the five-kingdom system, prokaryotes are placed in the kingdom _____.

monera

By definition a clade is _____.

monophyletic

Which of the following would be most useful in creating a phylogenetic tree of a taxon?

morphological data from fossil species

Phylogenetic trees constructed from evidence from molecular systematics are based on similarities in _____.

mutations to homologous genes

Which of the following would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock?

natural selection

Molecular clocks are based on the idea that _____.

on average neutral mutations arise at a constant rate

Concerning growth in genome size over evolutionary time, which of these is LEAST associated with the others?

orthologous genes

Carolus Linnaeus believed that species remained fixed in the form in which they had been created. Linnaeus would have been uncomfortable with ________.

phylogenies

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

plantae

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

polyphyletic taxa and paraphyletic taxa

Some molecular data place the giant panda in the bear family (Ursidae) but place the lesser panda in the raccoon family (Procyonidae). If the molecular data best reflect the evolutionary history of these two groups, then the morphological similarities of these two species is most likely due to _____.

possession of analogous (convergent) traits

Based on cladistics, which eukaryotic kingdom is polyphyletic and, therefore, unacceptable?

protista

In the five-kingdom system, which kingdom consists primarily of unicellular eukaryotes?

protista

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?

rRNA genes

If additional DNA sequence evidence shows that yeast genes for synthesizing proteins are more similar to protein-synthesizing genes in bacteria than those in archaea, a modern systematist would ________.

redraw the phylogeny to show eukaryotes sharing a more recent common ancestor with bacteria than archaea

The best classification system is that which most closely _____.

reflects evolutionary history

The legless condition that is observed in several groups of extant reptiles is the result of _____.

several instances of the legless condition arising independently of each other

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? Dogs and wolves _____.

share a very recent common ancestor

Fossil evidence indicates that some dinosaurs had feathers. If birds are indeed descended from those feathered dinosaurs, feathers are what kind of character?

shared ancestral character

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 ________.

structural analogies

Which branch of biology is concerned with the naming and classifying of organisms?

taxonomy

The term convergent evolution is most applicable to which of the following features?

the legless condition found in various lineages of extant lizards

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

their inclusiveness

Your professor wants you to construct a phylogenetic tree of orchids. She gives you tissue from seven orchid species and one lily. What is the most likely reason she gave you the lily?

to serve as an outgroup

If you were using cladistics to build a phylogenetic tree of cats, which of the following would be the best outgroup?

wolf