Question 1

Refer to the graph showing variations in oxygen levels during Earth's history.  Based on the graph, what is the most logical conclusion about the abundance of plant life in the time interval about 250 million years ago?

Accepted Answer

A)  Terrestrial plants went completely extinct. 
B)  The abundance of plant life dropped dramatically around this time. 
C)  Plants did not experience any major changes during this interval. 
D)  Plant life became much more abundant during this interval. 
E)  The most abundant types of plants alive at this time did not perform photosynthesis.

Question 2

A pure radioactive substance has a mass of 30 micrograms but had a mass of 240 micrograms 48 years ago.Assuming that the only changes in mass are due to radioactive decay, the half-life of the substance is _______ years.

Accepted Answer

A)  3 
B)  6 
C)  8 
D)  16 
E)  24

Question 3

At the global level, changing environmental conditions are currently characterized by a(n) increase in temperature caused by increased levels of _______ in the atmosphere.

Accepted Answer

The answer of At the global level, changing environmental conditions...

Question 4

Refer to the figure depicting a layer of Iridium at the Cretaceous-Tertiary (K/T) boundary between strata from two different periods in Earth's history.  Explain the significance of the globally distributed iridium layer found in strata with an age of approximately 65.5 million years.Explain which kinds of species went extinct at this time, and why (be as specific as possible).

Accepted Answer

The answer of Refer to the figure depicting a layer...

Question 5

In undisturbed sedimentary rock, strata from the _______ are immediately above rocks from the Ordovician.

Accepted Answer

A)  Devonian 
B)  Cambrian 
C)  Jurassic 
D)  Silurian 
E)  Cretaceous

Question 6

Based on the results of experiments raising flies at higher levels of oxygen, which of the following statements is most probable?

Accepted Answer

A)  Mutations that increase body size cannot occur. 
B)  Mutations that increase body size are more likely to be selectively advantageous at high levels of oxygen than at current levels of oxygen. 
C)  Mutations that increase body size are less likely to be selectively advantageous at high levels of oxygen than at current levels of oxygen. 
D)  Mutations that decrease body size are more likely to be selectively advantageous at high levels of oxygen than at current levels of oxygen. 
E)  Body size is not a heritable trait.

Question 7

At very small population densities, local extinctions can be caused by accidents such as not being able to find a mate.Examples of such phenomena are referred to collectively as the _______ effect.

Accepted Answer

The answer of At very small population densities, local extinctions...

Question 8

If 50 mg of a radioactive substance becomes 12.5 mg in 2,600 years, the half-life of the substance is _______ years.

Accepted Answer

The answer of If 50 mg of a radioactive substance...

Question 9

Among terrestrial species, those adapted to _______ conditions (such as higher elevations) are expected to be particularly vulnerable to climate change.

Accepted Answer

The answer of Among terrestrial species, those adapted to _______...

Question 10

You have discovered a nonavian dinosaur fossil in a sedimentary stratum with a nearby igneous intrusion.Based on this description, which type of analysis would not be appropriate for this sample?

Accepted Answer

A)  Stratigraphy 
B)  Paleomagnetic dating 
C)  Uranium-235 dating 
D)  Carbon-14 dating 
E)  Potassium-40 dating

Question 11

Which statement is true?

Accepted Answer

A)  Radioisotope dating of rocks, combined with fossil analysis, is the most powerful method of determining geological age. 
B)  Earth's magnetic field never changes. 
C)  Scientists divide geological periods into eras. 
D)  In order to date igneous rocks, geologists search for locations where sedimentary rocks have intruded into igneous rocks. 
E)  Radioisotope dating can only be performed on fossils.

Question 12

The Ottawa-Bonnechere Graben is a region in Canada characterized by two continental plates moving away from one another.The resulting geological feature is called a _______.

Accepted Answer

The answer of The Ottawa-Bonnechere Graben is a region in...

Question 13

One billion years ago, Earth was in the _______ eon.

Accepted Answer

The answer of One billion years ago, Earth was in...

Question 14

Refer to the figure.  The figure shows the _______ era, during which atmospheric O2 levels were almost equal to that of the present, and hard-bodied invertebrates were abundant and diverse in the sea.

Accepted Answer

A)  Precambrian 
B)  Mesozoic 
C)  Cenozoic 
D)  Proterozoic 
E)  Paleozoic

Question 15

The Cenozoic era began about _______ years ago.

Accepted Answer

A)  1 million 
B)  15 million 
C)  65 million 
D)  225 million 
E)  1 billion

Question 16

Refer to the figure, which illustrates changes in sea level over time.Asterisks indicate mass extinctions of marine organisms.  Which statement is supported by the figure?

Accepted Answer

A)  The Permian mass extinction was associated with a severe drop in sea level. 
B)  The Cambrian explosion was associated with a severe drop in sea level. 
C)  The Cretaceous mass extinction was associated with a global warming event. 
D)  A mass extinction of marine organisms occurred at the end of the Silurian period. 
E)  The largest mass extinction of marine organisms in history occurred between the Cambrian and Ordovician periods.

Question 17

Refer to the figure, which shows an imaginary name scheme for an undisturbed site with distinct fossil assemblages in the top five layers of strata.  Imagine that the Ware layer contains abundant and diverse shellfish and other marine fauna, while Sunderland contains the flora and fauna associated with lowland swamps. Which hypothesis is the most logical explanation to account for this?

Accepted Answer

A)  A global warming event caused a sea level rise at the end of the Sunderland period, leaving its swamps under water. 
B)  A global cooling event occurred at the end of the Ware period, lowering sea levels and turning the edge of the sea into a terrestrial habitat. 
C)  Lowland swamp organisms outcompeted the shellfish and came to dominate the region. 
D)  Volcanic activity created new land, which was then quickly vegetated. 
E)  A global warming event occurred at the end of the Ware period, altering the salinity of the ocean and causing part of it to dry up.

Question 18

Over geologic time, the concentration of O2 in Earth's atmosphere has increased.However, at the end of the _______ period, the O2 concentration decreased significantly and was associated with _______.

Accepted Answer

A)  Devonian; rapid evolution of lineages 
B)  Carboniferous; mass extinctions 
C)  Permian; mass extinctions 
D)  Cretaceous; rapid evolution of lineages 
E)  Cretaceous; mass extinctions

Question 19

Which of the following is in the corrrect order, from largest to smallest?

Accepted Answer

A)  Described fossil species; currently living described species; undescribed living species 
B)  Currently living described species; undescribed living species, described fossil species 
C)  Currently living described species; described fossil species; undescribed living species 
D)  Undescribed living species; described fossil species; currently living described species 
E)  Undescribed living species; currently living described species; described fossil species

Question 20

Vertebrates with well-protected eggs that can be laid in dry places originated during the Carboniferous period.These animals are known as

Accepted Answer

A)  trilobites. 
B)  ediacaran. 
C)  crinoids. 
D)  amniotes. 
E)  amphibians.

Exam 24: The History of Life on Earth

Refer to the graph showing variations in oxygen levels during Earth's history. Based on the graph, what is the most logical conclusion about the abundance of plant life in the time interval about 250 million years ago?