Question 1

If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (for example, lava, volcanic ash)nearby, then it should be

Accepted Answer

A)  easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been "reset" by the heat of the igneous rocks. 
B)  easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil. 
C)  easy to determine, as long as there is enough metamorphic rock nearby. 
D)  difficult to determine the absolute age of the fossil, because the "marker fossils" common to igneous rock will be absent. 
E)  difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock. 
A)  easy to determine the absolute age of the fossil, because the radioisotopes in the sediments will not have been "reset" by the heat of the igneous rocks. 
B)  easy to determine the absolute age of the fossil, because the igneous rocks will not have physically obstructed the deposition of sediment of a single age next to the fossil. 
C)  easy to determine, as long as there is enough metamorphic rock nearby. 
D)  difficult to determine the absolute age of the fossil, because the "marker fossils" common to igneous rock will be absent. 
E)  difficult to determine the absolute age of the fossil, because radiometric dating of sedimentary rock is less accurate than that of igneous rock.

Question 2

The first genes on Earth were probably

Accepted Answer

A)  DNA produced by reverse transcriptase from abiotically produced RNA. 
B)  DNA molecules whose information was transcribed to RNA and later translated in polypeptides. 
C)  auto-catalytic RNA molecules. 
D)  oligopeptides located within protobionts. 
A)  DNA produced by reverse transcriptase from abiotically produced RNA. 
B)  DNA molecules whose information was transcribed to RNA and later translated in polypeptides. 
C)  auto-catalytic RNA molecules. 
D)  oligopeptides located within protobionts.

Question 3

In the 5-7 million years that the hominid lineage has been diverging from its common ancestor with the great apes, dozens of hominid species have arisen, often with several species coexisting in time and space. As recently as 30,000 years ago, Homo sapiens coexisted with Homo neanderthalensis. Both species had large brains and advanced intellects. The fact that these traits were common to both species is most easily explained by which of the following?

Accepted Answer

A)  species selection 
B)  uniformitarianism 
C)  sexual selection 
D)  convergent evolution 
A)  species selection 
B)  uniformitarianism 
C)  sexual selection 
D)  convergent evolution

Question 4

If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then one should be surprised to observe evidence of which of the following within such microfossils?
I.double-stranded DNA
II.a nuclear envelope
III.a nucleoid
IV.a nucleolus
V.ribosomes

Accepted Answer

A)  II only 
B)  III only 
C)  II and IV 
D)  II, III, and IV 
E)  all five of these 
A)  II only 
B)  III only 
C)  II and IV 
D)  II, III, and IV 
E)  all five of these

Question 5

Which of the following factors weaken(s)the hypothesis of abiotic synthesis of organic monomers in early Earth's atmosphere?
1)the relatively short time between intense meteor bombardment and the appearance of the first life-forms
2)the lack of experimental evidence that organic monomers can form by abiotic synthesis
3)uncertainty about which gases comprised early Earth's atmosphere

Accepted Answer

A)  1 only 
B)  2 only 
C)  1 and 2 
D)  1 and 3 
E)  2 and 3 
A)  1 only 
B)  2 only 
C)  1 and 2 
D)  1 and 3 
E)  2 and 3

Question 6

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
-Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above, Earth's magnetic field has undergone reversal at an average rate of once every

Accepted Answer

A)  10,000 years. 
B)  25,000 years. 
C)  100,000 years. 
D)  250,000 years. 
E)  1,000,000 years. 
A)  10,000 years. 
B)  25,000 years. 
C)  100,000 years. 
D)  250,000 years. 
E)  1,000,000 years.

Question 7

Figure 25.3
-Hawaii is the most southeastern of the seven islands and is also closest to the sea-floor spreading center from which the Pacific plate originates, which lies about 5,600 km further to the southeast. Assuming equal sedimentation rates, what should be the location of the thickest sediment layer and, thus, the area with the greatest diversity of fossils above the oceanic crust?

Accepted Answer

A)  between the island of Hawaii and the sea-floor spreading center 
B)  around the base of the island of Hawaii 
C)  around the base of Kauai, the oldest of the Hawaiian islands 
D)  where the islands are most concentrated (highest number of islands per unit surface area) 
A)  between the island of Hawaii and the sea-floor spreading center 
B)  around the base of the island of Hawaii 
C)  around the base of Kauai, the oldest of the Hawaiian islands 
D)  where the islands are most concentrated (highest number of islands per unit surface area)

Question 8

The following questions refer to the paragraph below.
A sediment core is removed from the floor of an inland sea. The sea has been in existence, off and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilized in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonized by life.
   
Figure 25.2
-If arrows indicate locations in the column where fossils of a particular type (see key above)first appear, then which core in Figure 25.2 has the most accurate arrangement of fossils?

Accepted Answer

A)  core A 
B)  core B 
C)  core C 
D)  core D 
A)  core A 
B)  core B 
C)  core C 
D)  core D

Question 9

What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites?

Accepted Answer

A)  They had the same proportion of L and D isomers as Earth does today. 
B)  Their abundance would have been dramatically reduced upon passage through early Earth's oxidizing atmosphere. 
C)  There were more kinds of amino acids on the chondrites than are found in living organisms today. 
D)  They were delivered in the form of polypeptides. 
A)  They had the same proportion of L and D isomers as Earth does today. 
B)  Their abundance would have been dramatically reduced upon passage through early Earth's oxidizing atmosphere. 
C)  There were more kinds of amino acids on the chondrites than are found in living organisms today. 
D)  They were delivered in the form of polypeptides.

Question 10

Larval flies (maggots)express the Ubx gene in all of their segments, and thereby lack appendages. If this same gene continued to be expressed throughout subsequent developmental stages, except in the head region, and if the result was a fit, sexually mature organism that still strongly resembled a maggot, this would be an example of

Accepted Answer

A)  paedomorphosis. 
B)  homochrony. 
C)  heterochrony. 
D)  Two of the responses above are correct. 
A)  paedomorphosis. 
B)  homochrony. 
C)  heterochrony. 
D)  Two of the responses above are correct.

Question 11

One explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, modern insect wings could best be described as

Accepted Answer

A)  adaptations. 
B)  mutations. 
C)  exaptations. 
D)  isolating mechanisms. 
E)  examples of natural selection's predictive ability. 
A)  adaptations. 
B)  mutations. 
C)  exaptations. 
D)  isolating mechanisms. 
E)  examples of natural selection's predictive ability.

Question 12

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
-Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted above, what should be the approximate age of marine fossils found in undisturbed sedimentary rock immediately overlying the igneous rock at the arrow labeled "II"?

Accepted Answer

A)  10,000 years 
B)  250,000 years 
C)  400,000 years 
D)  1,000,000 years 
A)  10,000 years 
B)  250,000 years 
C)  400,000 years 
D)  1,000,000 years

Question 13

If one organ is an exaptation of another organ, then what must be true of these two organs?

Accepted Answer

A)  They are both vestigial organs. 
B)  They are both homologous organs. 
C)  They are undergoing convergent evolution. 
D)  They are found together in the same hybrid species. 
E)  They have the same function. 
A)  They are both vestigial organs. 
B)  They are both homologous organs. 
C)  They are undergoing convergent evolution. 
D)  They are found together in the same hybrid species. 
E)  They have the same function.

Question 14

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?

Accepted Answer

A)  How can amino acids, simple sugars, and nucleotides be synthesized abiotically? 
B)  How can RNA molecules catalyze reactions? 
C)  How did RNA sequences come to carry the code for amino acid sequences? 
D)  How could polymers involving lipids and/or proteins form membranes in aqueous environments? 
E)  How can RNA molecules act as templates for the synthesis of complementary RNA molecules? 
A)  How can amino acids, simple sugars, and nucleotides be synthesized abiotically? 
B)  How can RNA molecules catalyze reactions? 
C)  How did RNA sequences come to carry the code for amino acid sequences? 
D)  How could polymers involving lipids and/or proteins form membranes in aqueous environments? 
E)  How can RNA molecules act as templates for the synthesis of complementary RNA molecules?

Question 15

The following questions refer to the paragraph below.
A sediment core is removed from the floor of an inland sea. The sea has been in existence, off and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilized in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonized by life.
   
Figure 25.2
-Which of the following reasons may explain why the sediment core lacks fossils of dragonflies with 3-feet wingspans?
1)This particular sediment core includes the correct stratum, but the part of the stratum captured by the core lacks such fossils.
2)The sea was not present at this site during the time that 3-feet dragonflies existed.
3)Dragonflies have no hard parts, such as exoskeletons, to fossilize.
4)The sediments containing these fossils at this site may have been eroded away during a time when the sea had receded from this site.
5)Dragonflies are terrestrial; therefore, fossils of terrestrial organisms should not be expected in the sediments of seas.

Accepted Answer

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

Exam 25: The History of Life on Earth

If a fossil is encased in a stratum of sedimentary rock without any strata of igneous rock (for example, lava, volcanic ash)nearby, then it should be

The first genes on Earth were probably

What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites?

If one organ is an exaptation of another organ, then what must be true of these two organs?

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

Cell Communication

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

From Gene to Protein

Regulation of Gene Expression

Viruses

Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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