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.

several instances of the legless condition arising independently of each other

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.

their inclusiveness.

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

D and F

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.

phylogenies.

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.

reflects evolutionary history.

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

the legless condition found in various lineages of extant lizards

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.

homoplasy.

Which of the following 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

bones in the bat wing and bones in the human forelimb

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.

possession of analogous structures.

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.

molecular genetics.

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.

homoplasies.

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.

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.

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) polyphyletic taxa and monophyletic taxa
E) polyphyletic taxa and paraphyletic taxa
F) All of the choices are correct.

polyphyletic taxa and monophyletic taxa

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.

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.

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

shared derived characters

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.

mutations to homologous genes.

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.

It is a shared derived character of the mammals, but only if cynodonts are reclassified as
mammals.

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.

chimpanzees and humans.

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.

having a reliable average rate of mutation.

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.

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

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

mutation

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

natural selection

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

that coding for ribosomal RNA

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

molecular

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

Monera

Which eukaryotic kingdom is polyphyletic, and therefore unacceptable, based on cladistics?
A) Plantae
B) Fungi
C) Animalia
D) Protista
E) Monera

Protista