biology chapter 23 Flashcards
Which of the following statements is true regarding a phylogenetic tree?
Phylogenetic trees could be considered physical representations of hypotheses―those that seek to establish the evolutionary relationships between different organisms.
Both analogies and homologies are always used to create phylogenetic trees. In fact, analogies often provide more information regarding the evolutionary relationships between different species than do homologies.
false
Compared to more distantly related taxa, the DNA sequences of two closely related taxa are expected to show:
fewer differences because mutation rates are relatively constant and recently diverging species have had less time to accumulate differences.
Which of the following is most likely to fossilize?
a crayfish that died in its muddy burrow by a creek
The half-life of carbon-14 is 5730 years. Approximately how old is a fossil that contains .25g carbon-14 and .75g nitrogen-14?
11,460
Imagine that a taxonomist is provided with several flashcards on which the names of different species are written. She would likely organize these flashcards to construct a phylogenetic tree, and would pay no attention to which species belong to which genus or class.
false
Consider a generalized tree of life, with three large branches representing Archaea, Bacteria, and Eukarya. These three branches would represent different:
domains
Imagine that you are chatting with one of your friends. He states that reptiles are obviously a monophyletic group, as this group contains all of the organisms (outside of fish) that possess scales. This statement is:
false, as reptiles are a paraphyletic group; this group does not include birds, even though birds are thought to share a common ancestor with reptiles.
Imagine that a researcher has created two possible phylogenetic trees for a group of organisms―one that hypothesizes that five character changes occurred in a given group, and one that predicts only two character changes occurred in the same group. If the researcher wants to choose a phylogenetic tree based on parsimony, she will pick the phylogenetic tree with two character changes as her working hypothesis.
true
Which of the following statements are false regarding fossils?
Fossils can form with the same frequency in any environment. This includes lakebeds, the ocean floor, artic regions, and mountaintops.
The term “fossil” only includes skeletal remains of organisms, and does not include things like footprints, eggs or excrement.
In the plant fossil record, fossilized flower petals are much more common than fossilized pollen.
Molecular sequence data that depicts the divergence time between organisms can stand independently and never needs to be corroborated by fossil evidence.
Which of the following statements is true regarding phylogenetic trees?
Both morphological and molecular synapomorphies can be used to construct phylogenetic trees.
The half-life of carbon-14 is 5730 years. If a sample contained 100% carbon-14 and 0% nitrogen-14 at a point in time 17,190 years ago, then what percentage of carbon-14 would it contain today?
12.5%
Imagine that a scientist discovers a new, flying species of mammal that resembles a winged rabbit. What can the scientist say about this organism?
If molecular sequence data show that bats and this new species share a common ancestor, the wings of these two species would be considered homologous.
In order to be useful for constructing a phylogeny, a character must:
have a genetic basis
Which of the following homologies would be most helpful in identifying sister groups?
homologies that are only found in some, but not all, the members of a single group
