Exam 25: The History of Life on Earth

The following questions refer to the description and figure below. The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. Figure 25.1 -Which section of sea-floor crust should have the thickest layer of overlying sediment, assuming a continuous rate of sediment deposition?

Which of the following steps has not yet been accomplished by scientists studying the origin of life?

The following questions refer to the description and figure below. The figure represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note: The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley. Figure 25.1 -If a particular marine organism is fossilized in the sediments immediately overlying the igneous rock at the arrow labeled "II," at which other location, labeled A-E, would a search be most likely to find more fossils of this organism?

What is true of the fossil record of mammalian origins?

The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of

Many species of snakes lay eggs. However, in the forests of northern Minnesota where growing seasons are short, only live-bearing snake species are present. This trend toward species that perform live birth in a particular environment is an example of

If natural selection in a particular environment favored genetic systems that permitted the production of daughter "cells" that were genetically dissimilar from the mother "cells," then one should expect selection for which of the following? I.polynucleotide polymerase with low mismatch error rates II.polynucleotide polymerases without proofreading capability III.batteries of efficient polynucleotide repair enzymes IV.polynucleotide polymerases with proofreading capability V.polynucleotide polymerases with high mismatch error rates

An early consequence of the release of oxygen gas by plant and bacterial photosynthesis was to

How were conditions on the early Earth of more than 3 billion years ago different from those on today's Earth?

Figure 25.3 -According to the theory of sea-floor spreading, oceanic islands, such as the Hawaiian Islands depicted in Figure 25.3, form as oceanic crustal plates move over a stationary "hot spot" in the mantle. Currently, the big island of Hawaii is thought to be over a hot spot, which is why it is the only one of the seven islands that has active volcanoes. What should be true of the island of Hawaii? 1)Scientists in search of ongoing speciation events are more likely to find them here than on the other six islands. 2)Its species should be more closely related to those of nearer islands than to those of farther islands. 3)It should have a rich fossil record of terrestrial organisms. 4)There is a good chance of finding endemic species on this island. 5)On average, it should have fewer species per unit surface area than the other six islands.

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which graph below, if the results were produced abiotically, would have the greatest promise for revealing important information about the origin of Earth's first genetic system?

The following questions refer to this hypothetical situation. A female fly, full of fertilized eggs, is swept by high winds to an island far out to sea. She is the first fly to arrive on this island, and the only fly to arrive in this way. Thousands of years later, her numerous offspring occupy the island, but none of them resembles her. There are, instead, several species, each of which eats only a certain type of food. None of the species can fly, for their flight wings are absent, and their balancing organs (in other words, halteres) are now used in courtship displays. The male members of each species bear modified halteres that are unique in appearance to their species. Females bear vestigial halteres. The ranges of all of the daughter species overlap. -Fly species W, found in a certain part of the island, produces fertile offspring with species Y. Species W does not produce fertile offspring with species X or Z. If no other species can hybridize, then species W and Y

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from lungs of an ancestral fish is an example of

The following questions are based on the observation that several dozen different proteins comprise the prokaryotic flagellum and its attachment to the prokaryotic cell, producing a highly complex structure. -If the complex protein assemblage of the prokaryotic flagellum arose by the same general processes as those of the complex eyes of molluscs (such as squids and octopi), then

Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.

Which of these fly organs, as they exist in current fly populations, best fits the description of an exaptation?

An organism has a relatively large number of Hox genes in its genome. Which of the following is true of this organism?

If an increase in dicynodont species diversity (in other words, number of species)occurred soon after the Permian extinction, and if it occurred for the same general reason usually given for the increase in mammalian diversity following the Cretaceous extinction, then it should be attributed to

Which of the following is a defining characteristic that all protobionts had in common?

Bagworm moth caterpillars feed on evergreens and carry a silken case or bag around with them in which they eventually pupate. Adult female bagworm moths are larval in appearance; they lack the wings and other structures of the adult male and instead retain the appearance of a caterpillar even though they are sexually mature and can lay eggs within the bag. This is a good example of