Question 1

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?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 2

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

Accepted Answer

A)  synthesis of small RNA polymers by ribozymes 
B)  abiotic synthesis of polypeptides 
C)  formation of molecular aggregates with selectively permeable membranes 
D)  formation of protocells that use DNA to direct the polymerization of amino acids 
E)  abiotic synthesis of organic molecules

Question 3

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?

Accepted Answer

A)  B only 
B)  C only 
C)  D only 
D)  B and C 
E)  C and D

Question 4

What is true of the fossil record of mammalian origins?

Accepted Answer

A)  It is a good example of punctuated equilibrium. 
B)  It shows that mammals and birds evolved from the same kind of dinosaur. 
C)  It includes transitional forms with progressively specialized teeth. 
D)  It indicates that mammals and dinosaurs did not overlap in geologic time. 
E)  It includes a series that shows the gradual change of scales into fur.

Question 5

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

Accepted Answer

A)  a snowball Earth. 
B)  earlier genetic systems than those based on DNA. 
C)  the abiotic synthesis of organic monomers. 
D)  the delivery of organic matter to Earth by meteors and comets. 
E)  the endosymbiotic origin of mitochondria and chloroplasts.

Question 6

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

Accepted Answer

A)  natural selection. 
B)  sexual selection. 
C)  species selection. 
D)  goal direction in evolution. 
E)  directed selection.

Question 7

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

Accepted Answer

A)  I only 
B)  I and IV 
C)  I, III, and IV 
D)  II and V 
E)  II, III and V

Question 8

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

Accepted Answer

A)  generate intense lightning storms. 
B)  change the atmosphere from oxidizing to reducing. 
C)  make it easier to maintain reduced molecules. 
D)  cause iron in ocean water and terrestrial rocks to rust (oxidize). 
E)  prevent the formation of an ozone layer.

Question 9

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

Accepted Answer

A)  Only early Earth was intensely bombarded by large space debris. 
B)  Only early Earth had an oxidizing atmosphere. 
C)  Less ultraviolet radiation penetrated early Earth's atmosphere. 
D)  Early Earth's atmosphere had significant quantities of ozone.

Question 10

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.

Accepted Answer

A)  1, 2, and 3 
B)  1, 2, and 5 
C)  1, 2, 3, and 4 
D)  1, 2, 4, and 5 
E)  2, 3, 4, and 5

Question 11

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?

Accepted Answer

A)   
B)   
C)   
D)

Question 12

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

Accepted Answer

A)  have genomes that are still similar enough for successful meiosis to occur in hybrid flies. 
B)  have more genetic similarity with each other than either did with the other two species. 
C)  may fuse into a single species if their hybrids remain fertile over the course of many generations. 
D)  Three of the above statements are correct. 
E)  Two of the statements above are correct.

Question 13

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

Accepted Answer

A)  an evolutionary trend. 
B)  exaptation. 
C)  changes in Hox gene expression. 
D)  paedomorphosis. 
E)  adaptive radiation.

Question 14

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

Accepted Answer

A)  natural selection cannot account for the rise of the prokaryotic flagellum. 
B)  ancestral versions of this protein assemblage were either less functional or had different functions than modern prokaryotic flagella. 
C)  scientists should accept the conclusion that neither eyes nor flagella could have arisen by evolution. 
D)  we can conclude that both of these structures must have arisen through the direct action of an "intelligent designer."

Question 15

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

Accepted Answer

A)  vacant ecological niches 
B)  genetic drift 
C)  colonization of an isolated region that contains suitable habitat and few competitor species 
D)  evolutionary innovation 
E)  an adaptive radiation in a group of organisms (such as plants) that another group uses as food

Question 16

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

Accepted Answer

A)  wings 
B)  balancing organs 
C)  mouthparts 
D)  thoraxes 
E)  walking appendages

Question 17

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

Accepted Answer

A)  These genes are fundamental, and are expressed in all cells of the organism. 
B)  The organism must have multiple paired appendages along the length of its body. 
C)  The organism has the genetic potential to have a relatively complex anatomy. 
D)  Most of its Hox genes owe their existence to gene fusion events. 
E)  Its Hox genes cooperate to bring about sexual maturity at the proper stage of development.

Question 18

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

Accepted Answer

A)  an innovation among the dicynodonts that allowed them to fill brand-new niches. 
B)  the availability of previously occupied niches. 
C)  the extinction of the dinosaurs (except the birds). 
D)  their outcompetition of many other terrestrial organisms.

Question 19

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

Accepted Answer

A)  the ability to synthesize enzymes 
B)  a surrounding membrane or membrane-like structure 
C)  RNA genes 
D)  the ability to replicate RNA

Question 20

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

Accepted Answer

A)  allometric growth. 
B)  paedomorphosis. 
C)  sympatric speciation. 
D)  adaptive radiation. 
E)  changes in homeotic genes.

Exam 25: The History of Life on Earth