Deck 7: Earth and the Terrestrial Worlds

Question 1

Why can we not depend on the natural CO₂ cycle to lower carbon- dioxide levels?

A)It only removes small amounts of CO₂ from the atmosphere.
B)It operates too slowly.
C)There is no natural CO₂ cycle.

Answer 1

B

Question 2

Which of the following best describes the geological histories of the Moon and Mercury?

A)All four geological processes were important in their early histories, but only impact cratering still reshapes their surfaces today.
B)Impact cratering shaped these worlds early in their histories. Then, during the past few million years, they were reshaped by episodes of volcanism and tectonics.
C)Impact cratering is the only major geological process that has affected their surfaces.
D)Early in their histories, they suffered many impacts and experienced some volcanism and tectonics, but they now have little geological activity at all.

Answer 2

D

Question 3

Deep trenches in the ocean mark places where

A)plates slip sideways relative to one another.
B)plates pull apart, leaving great rifts in the crust.
C)one plate slides under another, returning older crust to the mantle.
D)hot mantle material rises upward and spreads sideways, pushing the plates apart.
E)plates push together, creating ocean mountain chains.

Answer 3

C

Question 4

Suppose Earth were to cool down a little. How would the carbon dioxide cycle tend to restore temperatures to normal?

A)Cooler temperatures allow carbon dioxide to form rain and rain out of the atmosphere.
B)Cooler temperatures cause volcanoes to become more active, so they release more carbon dioxide into the atmosphere than they do when temperatures are warmer.
C)Cooler temperatures lead to slower formation of carbonate minerals in the ocean, so carbon dioxide released by volcanism builds up in the atmosphere and strengthens the greenhouse effect.
D)Cooler temperatures mean more ice and more erosion, which somehow makes the planet warm up.

Question 5

A planet is most likely to have tectonic activity if it has

A)high internal temperature.
B)high surface gravity.
C)a dense atmosphere.
D)low internal temperature.
E)low surface gravity.

Question 6

What makes us think that Mars must once have had an atmosphere that was warmer and had higher surface pressure?

A)We think it for purely theoretical reasons, based on calculations showing that the Sun has brightened with time.
B)The fact that parts of Mars have a lot of craters tell us that Mars must once have been much warmer.
C)The atmosphere is too cold and thin for liquid water today, yet we see evidence that water flowed on the surface in the past.
D)The presence of inactive volcanoes on Mars tells us that there must once have been a lot of outgassing, and hence a thicker atmosphere.

Question 7

The CO₂ concentration of the atmosphere has increased by about _ since 1750.

A)1000 parts- per- million
B)10 parts- per- million
C)100 parts- per- million
D)None. It has decreased.

Question 8

What do we mean by a runaway greenhouse effect?

A)a greenhouse effect that starts on a planet but later disappears as gases are lost to space
B)a greenhouse effect that heats a planet so much that its surface rock melts
C)a process that heats a planet like a greenhouse effect, but that involves a completely different mechanism of heating that doesn't actually involve greenhouse gases
D)a greenhouse effect that keeps getting stronger until all of a planet's greenhouse gases are in its atmosphere

Question 9

Why do we think Mercury has so many tremendous cliffs?

A)They probably formed when a series of large impacts hit Mercury one after the other.
B)They represent one of the greatest mysteries in the solar system, as no one has suggested a reasonable hypothesis for their formation.
C)They were probably carved in Mercury's early history by running water.
D)They are almost certainly volcanic in origin, carved by flowing lava.
E)They were probably formed by tectonic stresses when the entire planet shrank as its core cooled.

Question 10

The Sun is gradually increasing in luminosity as it ages. It is 20% more luminous than it was when it was born. Why isn't this considered to be an explanation for global warming?

A)The amount of energy the Earth receives from the Sun remains constant regardless of what the Sun does.
B)The scientists are covering up this potentially valid explanation.
C)What the Sun was doing millions of years ago is what determines Earth's temperature, since the Earth doesn't respond directly to what the Sun is doing today.
D)The Sun is increasing in luminosity much too slowly, over many millions of years.

Question 11

What kind of thermal radiation does the Earth emit?

A)infrared light
B)visible light
C)visible and ultraviolet light
D)infrared and visible light
E)infrared, visible, and ultraviolet light

Question 12

What do we mean when we say that the terrestrial worlds underwent differentiation?

A)They lost interior heat to outer space.
B)Their surfaces show a variety of different geological features resulting from different geological processes.
C)When their interiors were molten, denser materials sank toward their centers and lighter materials rose toward their surfaces.
D)The five terrestrial worlds all started similarly but ended up looking quite different.

Question 13

Earth has been gradually warming over the past few decades. Based on a great deal of evidence, scientists believe that this warming is caused by .

A)the human release of chemicals called CFCs into the stratosphere
B)the fact that our politicians spout a lot of hot air
C)human activities that are increasing the concentration of greenhouse gases in Earth's atmosphere
D)the increase in forest fires during recent years

Question 14

Why does Earth have the strongest magnetic field among the terrestrial worlds?

A)It is the most volcanically active world.
B)It rotates much faster than any other terrestrial world.
C)It is the only one that has both a partially molten metallic core and reasonably rapid rotation.
D)It is the only one that has a metallic core.
E)It is by far the largest terrestrial world.

Question 15

Why does the Moon have a layer of "powdery soil" on its surface?

A)It is the result of countless tiny impacts by small particles striking the Moon.
B)It exists because the Moon accreted from powdery material after a giant impact blasted the Earth.
C)It is made by the same processes that make powdery sand on Earth.
D)Recent, large impacts shattered lunar rock to make this soil.

Question 16

The core, mantle, and crust of a planet are defined by differences in their

A)density.
B)geological activity.
C)strength.
D)temperature.

Question 17

Which of the following does not have a major effect in shaping planetary surfaces?

A)magnetism
B)erosion
C)tectonics
D)volcanism
E)impact cratering

Question 18

The choices below describe four hypothetical planets. Which one would you expect to have the most features of erosion? (Assume the planets orbit a star just like the Sun and that they are all the same age as the planets in our solar system.)

A)Size: same as Venus. Distance from Sun: same as Mars. Rotation rate: once every 25 hours.
B)Size: twice as big as Earth. Distance from Sun: same as Mercury. Rotation rate: once every 6 months.
C)Size: same as Mars. Distance from Sun: same as Earth. Rotation rate: once every 18 hours.
D)Size: same as the Moon. Distance from Sun: same as Mars. Rotation rate: once every 10 days.

Question 19

Ridges in the middle of the ocean are places where

A)one plate slides under another, returning older crust to the mantle.
B)plates slip sideways relative to one another.
C)hot mantle material rises upward, creating volcanic islands.
D)plates push together, creating ocean mountain chains.
E)hot mantle material rises upward and spreads sideways, pushing the plates apart.

Question 20

There are no auroras on Venus because it

A)is too hot.
B)lacks a strong magnetic field.
C)lacks strong winds.
D)lacks atmospheric oxygen.

Question 21

How fast do tectonic plates move on Earth?

A)a few kilometers per century
B)a few centimeters per century
C)quite fast, but only during earthquakes
D)about 1 mile per hour
E)a few centimeters per year

Question 22

Why is Mars red?

A)Its surface is made of ices that absorb red light.
B)Its surface is made of ices that absorb blue light.
C)Its atmosphere scatters blue light more effectively than red light.
D)It is made primarily of red clay.
E)Its surface rocks were rusted by oxygen.

Question 23

Which two factors are most important to the existence of plate tectonics on Earth?

A)mantle convection and a thin lithosphere
B)oxygen in the atmosphere and mantle convection
C)Earth's liquid outer core and solid inner core
D)the existence of life and oxygen in the atmosphere

Question 24

Which of the following best describes the lunar maria?

A)frozen oceans of liquid water on the Moon
B)mountainous regions on the Moon
C)densely cratered regions on the Moon
D)relatively smooth, flat plains on the Moon

Question 25

If the Earth were to warm up a bit, what would happen?

A)Carbonate materials would form in the oceans more rapidly, the atmospheric CO₂ content would decrease, and the greenhouse effect would weaken.
B)There would be a runaway greenhouse effect, with the Earth becoming ever hotter until the oceans evaporated (as may have happened on Venus).
C)Carbonate materials would form in the oceans more rapidly, the atmospheric CO₂ content would decrease, and the greenhouse effect would strengthen.
D)The ice caps would melt and cool the Earth back to its normal temperature.
E)Carbonate materials would form in the oceans more slowly, the atmospheric CO₂ content would increase, and the greenhouse effect would strengthen.

Question 26

What is a magnetosphere?

A)a region of space around a planet in which the planet's magnetic field can trap charged particles
B)the uppermost layer of any planetary atmosphere
C)the region in a planet's atmosphere in which auroras occur
D)the layer of a planet in which its magnetic field is generated

Question 27

Many scientists suspect that Venus has a stronger and thicker lithosphere than Earth. If this is true, which of the following could explain it?

A)the apparent lack of plate tectonics on Venus
B)the high surface temperature that has "baked out" all the liquid water from Venus's crust and mantle
C)the slow rotation of Venus
D)the smaller size of Venus, which has allowed it to lose much more internal heat than Earth

Question 28

Which of the following describes tectonics?

A)the excavation of bowl- shaped depressions by asteroids or comets striking a planet's surface
B)the eruption of molten rock from a planet's interior to its surface
C)the disruption of a planet's surface by internal stresses
D)the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

Question 29

Which of the following is the underlying reason why Venus has so little wind erosion?

A)its thick atmosphere
B)its slow rotation
C)its relatively close distance to the Sun
D)its small size

Question 30

Recent evidence suggests that Mars once had a global magnetic field. Assuming this is true, which of the following could explain why Mars today lacks a global magnetic field like that of Earth?

A)Mars is too far from the Sun to have a global magnetic field.
B)Mars rotates much slower than the Earth.
C)The Martian core is made of rock, while Earth's core is made of metal.
D)Mars's interior has cooled so much its molten core layer no longer undergoes convection.

Question 31

All of the statements below are true. Which one gives the primary reason why the surface of Venus today is some 450°C hotter than the surface of Earth?

A)Venus is only about 73% as far from the Sun as Earth.
B)Venus has a much higher reflectivity than Earth.
C)Venus has a higher atmospheric pressure than Earth.
D)Venus has a much stronger greenhouse effect than Earth.

Question 32

Which of the following gases absorbs ultraviolet light best?

A)carbon dioxide
B)oxygen
C)nitrogen
D)ozone
E)hydrogen

Question 33

Why would the weather become more severe as the greenhouse effect increased?

A)Warming would increase the evaporation of the oceans, leading to more water in the atmosphere and more frequent and severe storms.
B)Warming of the planet would lead to terrible droughts and reduce the amount of water on the Earth.
C)The depleted ozone layer would let in more particles from the solar wind.
D)Warming would dry out the atmosphere and the crust, leading to devastation of the Earth through more meteor bombardment and volcanism.
E)all of the above

Question 34

Which of the terrestrial worlds has the strongest magnetic field?

A)the Moon
B)Mars
C)Venus
D)Earth
E)Mercury

Question 35

On average, how fast do the plates move on the Earth?

A)about 1 mile per hour
B)a few centimeters per year
C)a few kilometers per year
D)a few millimeters per century

Question 36

Spacecraft have landed on all the terrestrial worlds except

A)Venus.
B)Mercury.
C)Moon.
D)Mars.

Question 37

What is the most important factor that determines the thickness, and therefore strength, of the lithosphere?

A)distance of planet from Sun
B)internal temperature
C)pressure
D)composition

Question 38

Why is Mars red?

A)Chemical reactions between surface rock and atmospheric oxygen literally rusted the surface.
B)The red color is caused by water ice chemically bound in surface rock.
C)The red color of Mars is a result of the scattering of light in the Martian sky.
D)Martian volcanoes released a much redder lava than volcanoes on Earth.

Question 39

Why does the burning of fossil fuels increase the greenhouse effect on Earth?

A)Burning fuel warms the planet.
B)Burning depletes the amount of ozone, thereby warming the planet.
C)Burning releases carbon dioxide into the atmosphere.
D)Burning produces infrared light, which is then trapped by existing greenhouse gases.
E)All of the above are true.

Question 40

Which two factors are critical to the existence of the carbon dioxide (CO₂)cycle on Earth?

A)life and atmospheric oxygen
B)plate tectonics and liquid water oceans
C)life and active volcanism
D)active volcanism and active tectonics

Question 41

Which of the following describes impact cratering?

A)the excavation of bowl- shaped depressions by asteroids or comets striking a planet's surface
B)the eruption of molten rock from a planet's interior to its surface
C)The disruption of a planet's surface by internal stresses
D)the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

Question 42

Which of the following best explain what we think happened to outgassed water vapor on Venus?

A)It is frozen as water ice in craters near the poles.
B)Water was removed from the atmosphere by chemical reactions with surface rock.
C)Ultraviolet light split the water molecules, and the hydrogen then escaped to space.
D)It turned into carbon dioxide by reacting with nitrogen in Venus's atmosphere.

Question 43

Why does Earth have so little carbon dioxide in its atmosphere compared to Venus?

A)Chemical reactions turned Earth's carbon dioxide into nitrogen.
B)Earth has just as much carbon dioxide as Venus, but most of it is locked up in carbonate rocks rather than being free in the atmosphere.
C)Earth once had a lot of carbon dioxide, but it was lost to space during the heavy bombardment early in our solar system's history.
D)Earth's volcanoes outgassed far less carbon dioxide than those on Venus.

Question 44

Suppose Earth's atmosphere had no greenhouse gases. Then Earth's average surface temperature would be

A)15°C, or about the same as it is now.
B)- 16°C, which is well below freezing.
C)20°C, or about 5°C warmer than it is now.
D)0°C, or about the freezing point for water.
E)10°C or about 5°C cooler than it is now.

Question 45

How large is an impact crater compared to the size of the impactor?

A)1,000 times larger
B)10- 20 percent larger
C)the same size
D)100 times larger
E)10 times larger

Question 46

What observational evidence supports the idea that Mercury once shrank by some 20 kilometers in radius?

A)Mercury's unusually high density
B)the characteristics of the Caloris Basin
C)the presence of many impact craters
D)the presence of many long, tall cliffs

Question 47

The footprints left on the moon by the Apollo astronauts will likely last for

A)a few decades.
B)the remaining existence of the Moon.
C)millions of years.
D)no time; they were quickly erased by micrometeorites.

Question 48

Which of the following best describes how the greenhouse effect works?

A)Greenhouse gases absorb X- rays and ultraviolet light from the Sun, and this absorbed radiation then heats the atmosphere and the surface.
B)Greenhouse gases absorb infrared light coming from the Sun, and this absorbed sunlight heats the lower atmosphere and the surface.
C)The greenhouse effect is caused primarily by ozone, which absorbs ultraviolet light and thereby makes the atmosphere much hotter than it would be otherwise.
D)A planet's surface absorbs visible sunlight and returns this absorbed energy to space as infrared light. Greenhouse gases slow the escape of this infrared radiation, which thereby heats the lower atmosphere.

Question 49

Which of the following does not provide evidence that Mars once had abundant liquid water on its surface?

A)the presence of very old craters that appear to have been eroded by rain
B)the presence of features that look like dried up river beds
C)the presence of what looks like sedimentary layers in some crater bottoms
D)the presence of canali, discovered in the late 1800s by Giovanni Schiaparelli and mapped by Percival Lowell

Question 50

Based on its surface features, the most important event on Venus in the past billion years or so was .

A)a global "repaving" that erased essentially all the surface features that had existed earlier
B)the impact of an unusually large asteroid that left a deep scar on one side of the planet
C)the eruption of a giant volcano that formed one of Venus's "continents"
D)the onset of mantle convection, which caused Venus's lithosphere to split into plates like those on Earth

Question 51

The three principal sources of the internal heat of terrestrial planets are

A)accretion, differentiation, and radioactivity.
B)convection, differentiation, and eruption.
C)conduction, convection, and eruption.
D)accretion, differentiation, and eruption.
E)conduction, differentiation, and accretion.

Question 52

Rank the five terrestrial worlds in order of size from smallest to largest.

A)Mercury, Moon, Venus, Earth, Mars
B)Moon, Mercury, Venus, Earth, Mars
C)Mercury, Venus, Earth, Moon, Mars
D)Moon, Mercury, Mars, Venus, Earth
E)Mercury, Moon, Mars, Earth, Venus

Question 53

The greenhouse effect makes Earth warmer than it would be otherwise by about

A)15 K.
B)30 K.
C)- 16 K.
D)There is no greenhouse effect.

Question 54

The processes responsible for virtually all surface geology are .

A)impact cratering, volcanisms, tectonics, and erosion
B)accretion, differentiation, and radioactive decay
C)eruptions, lava flows, and outgassing
D)convection, conduction, and radiation

Question 55

Why is continental crust lower in density than seafloor crust?

A)Continental crust is made of rock, while seafloor crust has more metals.
B)Continental crust is actually denser than seafloor crust.
C)Continental crust is made from volcanic rock called basalt, which is lower in density than what the seafloor crust is made from.
D)Seafloor crust is more compact due to the weight of the oceans, but it is made of the same material as the continental crust.
E)Continental crust is made from remelted seafloor crust and therefore only the lower- density material rises to form it.

Question 56

What are the circumstances under which convection can occur in a substance?

A)when the substance is strongly cooled from underneath
B)when the substance is strongly heated from underneath
C)when the substance is subjected to a strong magnetic field
D)when the substance is strongly shaken or disturbed by a strong wind
E)when dense material is being added to the substance

Question 57

Suppose we use a baseball to represent Earth. On this scale, the other terrestrial worlds (Mercury, Venus, the Moon, and Mars)would range in size approximately from that of .

A)a dust speck to a basketball
B)a golf ball to a beach ball
C)a golf ball to a baseball
D)a dust speck to a golf ball

Question 58

The Caloris Basin on Mercury covers a large region of the planet, but few smaller craters have formed on top of it. From this we conclude that

A)the Caloris Basin formed toward the end of the solar system's period of heavy bombardment.
B)the Caloris Basin was formed by a volcano.
C)Mercury's atmosphere prevented smaller objects from hitting the surface.
D)erosion destroyed the smaller craters that formed on the basin.
E)only very large impactors hit Mercury's surface in the past.

Question 59

How does seafloor crust differ from continental crust?

A)Seafloor crust is thicker, older, and higher in density.
B)Seafloor crust is thicker, younger, and lower in density.
C)Seafloor crust is thinner, younger, and higher in density.
D)Seafloor crust is thinner, older, and lower in density.

Question 60

Rank these planets in order of the strength of the greenhouse effect on the planet, from the least to the greatest.

A)Mars, Earth, Venus, Mercury
B)Mercury, Venus, Earth, Mars
C)Mars, Mercury, Earth, Venus
D)Mercury, Earth, Mars, Venus
E)Mercury, Mars, Earth, Venus

Question 61

Why is Mars so much colder than the Earth?

A)because Mars is farther from the Sun
B)because Mars has a much thinner, more diffuse atmosphere
C)because Mars has a little less gravity than the Earth
D)because the albedo of Mars is higher than the Earth

Question 62

What is the importance of the carbon dioxide (CO₂)cycle?

A)It makes the growth of continents possible.
B)It regulates the carbon dioxide concentration of our atmosphere, keeping temperatures moderate.
C)It allows for an ultraviolet- absorbing stratosphere.
D)It will prevent us from suffering any consequences from global warming.

Question 63

How deep is an impact crater compared to its width?

A)10- 20%
B)100- 200%
C)30- 40%
D)1- 10%
E)50- 100%

Question 64

Mars' atmosphere is mostly carbon- dioxide. Why does it not experience a runaway greenhouse effect like Venus?

A)It is protected by its magnetic field.
B)Its atmosphere is too thin.
C)It does not have enough additional water to magnify the warming.

Question 65

Why is Earth's continental crust lower in density than seafloor crust?

A)Continental crust comes from Earth's inner core while seafloor crust comes from the outer core.
B)Continental crust is made as the lowest- density seafloor crust melts and erupts to the surface near subduction zones.
C)Continental crust comes from volcanoes while seafloor crust comes from geysers.
D)Continental crust is made from a low- density volcanic rock called basalt.

Question 66

What process has shaped Earth's surface more than any other?

A)plate tectonics
B)impact cratering
C)acid rain
D)volcanism
E)wind erosion

Question 67

Why does increasing the amount a greenhouse gas increase the temperature of a planet?

A)Greenhouse gases emit visible light.
B)Greenhouse gases absorb infrared light.
C)Greenhouse gases emit infrared light.
D)Greenhouse gases absorb visible light.

Question 68

Which of the following describes erosion?

A)the excavation of bowl- shaped depressions by asteroids or comets striking a planet's surface
B)the eruption of molten rock from a planet's interior to its surface
C)the disruption of a planet's surface by internal stresses
D)the wearing down or building up of geological features by wind, water, ice, and other phenomena of planetary weather

Question 69

All the following statements about Mars are true. Which one might have led to a significant loss of atmospheric gas to space?

A)Mars probably once had a much higher density of greenhouse gases in its atmosphere than it does today.
B)The axis tilt of Mars is thought to change significantly with time.
C)Mars lost any global magnetic field that it may once have had.
D)Outgassed water molecules are split apart by ultraviolet light, and the oxygen then reacts chemically with surface rock on Mars.

Question 70

Which of these is the dominant mechanism for the removal of carbon dioxide from the atmosphere?

A)subduction
B)dissolving carbon dioxide in seawater
C)formation of carbonate- rich rocks at the seafloor
D)photosynthesis in plants

Question 71

Which of the following is the most basic definition of a greenhouse gas?

A)a gas that makes a planet much hotter than it would be otherwise, even in small amounts
B)a gas that reflects a lot of sunlight
C)a gas that absorbs infrared light
D)a gas that keeps warms air from rising, and therefore warms the surface

Question 72

From center to surface, which of the following correctly lists the interior layers of a terrestrial world?

A)core, mantle, crust
B)core, crust, lithosphere
C)mantle, crust, core
D)mantle, core, crust

Question 73

What kind of surface features may result from tectonics?

A)volcanos
B)mountains
C)cliffs
D)valleys
E)all of the above

Question 74

When we see a region of a planet that is not as heavily cratered as other regions, we conclude that

A)the surface in the region is older than the surface in more heavily cratered regions.
B)the planet is rotating very slowly and only one side was hit by impactors.
C)there is little volcanic activity to create craters.
D)the surface in the region is younger than the surface in more heavily cratered regions.
E)the planet formed after the age of bombardment and missed out on getting hit by leftover planetesimals.

Question 75

The CO₂ concentration of the atmosphere has increased by about _ since 1750.

A)250%
B)2)5 %
C)25%
D)None. It has decreased.

Question 76

A terrestrial world's lithosphere is _ .

A)the interior region in which the planet's magnetic field is generated
B)a layer of hot, molten rock encompassing the core and part of the mantle
C)a thin layer of rock that lies between the mantle and crust
D)a layer of relatively strong, rigid rock, encompassing the crust and part of the mantle

Question 77

Valles Marineris is a(n)

A)large valley on the Moon.
B)huge series of cliffs on Mercury.
C)large canyon on Mars.
D)extensive plain on Mars.
E)large canyon on Venus.

Question 78

How did the lunar maria form?

A)The maria are the result of gradual erosion by micrometeorites striking the Moon.
B)Large impacts fractured the Moon's lithosphere, allowing lava to fill the impact basins.
C)Volatiles escaping from the Moon's interior heated and eroded the surface in the regions of the maria.
D)The giant impact that created the Moon left smooth areas that we call the maria.
E)The early bombardment created heat that melted the lunar surface in the regions of the maria.

Question 79

Which internal energy source produces heat by converting gravitational potential energy into thermal energy?

A)accretion
B)differentiation
C)radioactivity
D)both A and B
E)all of the above

Question 80

What type of stresses broke Earth's lithosphere into plates?

A)volcanism, which produced heavy volcanoes that bent and cracked the lithosphere
B)impacts of asteroids and planetesimals
C)cooling and contracting of the planet's interior, which caused the mantle and lithosphere to be compressed
D)internal temperature changes that caused the crust to expand and stretch
E)the circulation of convection cells in the mantle, which dragged against the lithosphere