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If the genes of yeast are 50% orthologous to those of humans, and if the genes of mice are 99% orthologous to those of humans, then what percentage of the genes of fish might one validly predict to be orthologous to the genes of humans?
When using a cladistic approach to systematics, which of the following is considered most important for classification?
shared derived characters
The common ancestors of birds and mammals were very early (stem) reptiles, which almost certainly possessed 3-chambered hearts (2 atria, 1 ventricle). Birds and mammals, however, are alike in having 4-chambered hearts (2 atria, 2 ventricles). The 4-chambered hearts of birds and mammals are best described as
Which of these would, if it had acted upon a gene, prevent this gene from acting as a reliable molecular clock?
D. natural selection
If this figure is an accurate depiction of relatedness, then which taxon is unacceptable, based on cladistics?
A researcher wants to determine the genetic relatedness of several breeds of dog (Canis familiaris). The researcher should compare homologous sequences of ____ that are known to be ____.
D. proteins or nucleic acids; poorly conserved
The various taxonomic levels (viz, genera, classes, etc.) of the hierarchical classification system differ from each other on the basis of
C. their inclusiveness
What is true of gene duplication (NOTE: gene duplication is a process that is distinct from DNA replication)?
E. It can increase the size of a genome over evolutionary time.
Which process hinders clarification of the deepest branchings in a phylogenetic tree that depicts the origins of the three domains?
D. horizontal gene transfer
Which statement represents the best explanation for the observation that the nuclear DNA of wolves and domestic dogs has a very high degree of homology?
d. Dogs and wolves shared a common ancestor very recently.
A phylogenetic tree that is "rooted" is one
at whose base is located the common ancestor of all taxa depicted on that tree
To apply parsimony to constructing a phylogenetic tree,
D. choose the tree that represents the fewest evolutionary changes, either in DNA sequences or morphology.
Darwin analogized the effects of evolution as the above-ground portion of a many-branched tree, with extant species being the tips of the twigs. The common ancestor of two species is most analogous to which anatomical tree part?
B. a node where two twigs diverge
A taxon, all of whose members have the same common ancestor, is
E. both paraphyletic and monophyletic
The common housefly belongs to all of the following taxa. Assuming you had access to textbooks or other scientific literature, knowing which of the following should provide you with the most specific information about the common housefly?
C. Genus Musca
Theoretically, molecular clocks are to molecular phylogenies as radiometric dating is to phylogenies that are based on the
A. fossil record
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
D. possession of analogous structures.
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