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BSC2011
Chapter 26- Phylogeny and the Tree of Life
| Question | Answer |
|---|---|
| The point at which two or more lineages diverge from their common ancestor is called a(n) ________________ or node. | branch point |
| are groups of organisms that share a unique common ancestor not shared by any other groups. | sister taxa |
| Each branch tip on a phylogenetic tree represents a specific group of organisms known as a(n)____________. | taxon |
| The horizontal line indicating a branch on a phylogenetic tree represents ancestral forms of the named taxon, thereby illustrating the _________________ leading to that taxon. | evolutionary lineage |
| The taxon that shares the most recent common ancestor with frogs is fishes. | false |
| Frogs and humans are more distantly related than are lizards and humans. | true |
| In this tree, lizards are the sister taxon of the lineage that includes humans and chimps. | true |
| Fishes and chimps have no common ancestors. | false |
| Animals that possess homologous structures probably _____. | evolved from the same ancestor |
| Look at this character table. Rattlesnakes (like turtles) are reptiles, yet they do not have four limbs. In fact, they have no apparent limbs. | The presence or absence of four limbs, on its own, could be misleading when considering the evolutionary relationships of rattlesnakes. |
| 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. |
| Molecular clocks are based on the idea that _____. | on average neutral mutations arise at a constant rate |
| 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. |
| Which of the following is the correct order of taxonomic levels in the Linnean system of classification, from most to least inclusive? | Which of the following is the correct order of taxonomic levels in the Linnean system of classification, from most to least inclusive? |
| What is a primary reason why a three-domain taxonomic scheme has been adopted over the previous five-kingdom taxonomic scheme? | Phylogenies based on genetic data revealed that some prokaryotes (kingdom Monera) differ as much from each other as they differ from eukaryotes. |
| The separate lineages leading to dolphins and sharks both evolved streamlined bodies, dorsal fins, and broad tail fins as adaptations to efficient locomotion in a marine environment. In this comparison, the bodies and fins of dolphins and sharks are wha | analogous |
| Birds and mammals have a four-chambered heart, but most reptiles have a three-chambered heart. How does this fact affect the construction of phylogenetic trees for these groups? | The most likely tree is not always the most parsimonious. |
| In cladistics, biologists attempt to place species into groups that each include an ancestral species and all of its descendants. A group that is paraphyletic fails to accomplish this goal in what way? | It consists of an ancestral species and some, but not all, of its descendants. |
| By applying a molecular clock, researchers have proposed that the first HIV-1 M invasion into humans occurred in the __________. | 1930s |
| Which of the following is a true statement concerning horizontal gene transfer? | Horizontal gene transfer is known to occur within both prokaryotes and eukaryotes. |
| Why are phylogenetic trees considered hypotheses? | A phylogenetic tree can be used to make testable predictions |
| The binomial system assigns to each organism a unique name that describes its _______________. | genus and species |
| Rabbits and guinea pigs both belong to class Mammalia. This means they must also both belong to __________. | phylum chrodata |
| A bald eagle and a black bear both have four limbs with digits because they are both tetrapods, descendants of a fourlimbed ancestor. In this comparison, the limbs of the eagle and the bear are what type of structure? | homolgous |
| A taxon _____________________. | is a formal grouping at any given level |
| What is the basis for the use of a molecular clock to determine the absolute time of evolutionary change? | Nucleotide substitutions in a gene occur at a relatively constant rate. |
| Which of the following is an assumption that should be made when reading a phylogenetic tree? | None of the listed assumptions should be made. |
| 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 |
| Sister taxa on a phylogenetic tree are defined as groups that __________. | share an immediate common ancestor and are each other’s closest relatives |
| The principle of maximum parsimony is applied to the process of constructing a phylogenetic tree in what way? | The tree that requires the fewest evolutionary events, as measured by the origin of shared derived characters, is selected. |
| Two genes are recognized as orthologous if _______________. | they are homologous genes found in different species, and their divergence traces back to speciation events that produced the species |
| The term polytomy refers to a situation in which __________. | there is a branch point on a phylogeny from which more than two descendent groups emerge |
| Researchers can use molecular homologies to __________. | reveal the number of mutations in a particular sequence that has occurred in each species since they diverged from a common ancestor |
| In a cladistic approach to systematics, an outgroup is _____________. | a species or group of species from an evolutionary lineage that is known to have diverged before the lineage that includes all the species under study |
| Which of the following would be the least useful in determining the relationships among various species? | analogous structures |
| If you wanted to determine the lineage of plants that have evolved on a relatively young archipelago—approximately 15,000 years old—what type of nucleic acid should you compare? | mtDNA |
| A phylogenetic tree of bird families constructed by cladistic analysis would be a hypothesis about which of the following? | Evolutionary relationships among bird families |
| Looking at the character table and phylogenetic tree above, which of the following is a true statement? | A backbone is a shared ancestral character in mammals (leopard). |
| Which of the following best summarizes the neutral theory? | Darwinian selection does not influence a lot of evolutionary change in genes and proteins because many of these changes do not affect fitness. |
| Using cladistic analysis, a taxonomist wishes to construct a phylogenetic tree showing the relationships among various species of mammals. Which of the following would be the least useful for this purpose? | The fact that all mammals have hair |
| The idea of using molecules as clocks to time evolutionary events is very attractive, but there are many problems in actually applying the technique. What seems to be the best way to get reliable results? | It is important to use as many genes as possible. With this approach, fluctuations in evolutionary rate will tend to average out. |
| What is the relationship between systematics and taxonomy? | Systematics is a discipline within taxonomy |
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