Question 1

The Van Allen belts are:

Accepted Answer

A) regions of Earth in which no seismic activity is detected from earthquakes. 
B) dense collections of small rocks surrounding the major planets. 
C) two doughnut-shaped rings of charged particles, surrounding the equatorial regions of Earth at very high altitudes. 
D) undersea mountain ranges in the centers of the oceans. 
A) regions of Earth in which no seismic activity is detected from earthquakes. 
B) dense collections of small rocks surrounding the major planets. 
C) two doughnut-shaped rings of charged particles, surrounding the equatorial regions of Earth at very high altitudes. 
D) undersea mountain ranges in the centers of the oceans.

Question 2

How stable is the nitrogen in Earth's atmosphere?

Accepted Answer

A) Nitrogen is an inert gas and reacts very little, so it remains essentially constant. 
B) Nitrogen is light enough that it is continually escaping Earth's gravity in significant amounts, so it must be replaced by outgassing from volcanoes. 
C) Nitrogen reacts with water vapor to form various hydrocarbons. These are subducted under the crust and then outgassed from volcanoes. 
D) Bacteria process nitrate minerals and release nitrogen. Atmospheric nitrogen combines with oxygen to eventually form nitrates. 
A) Nitrogen is an inert gas and reacts very little, so it remains essentially constant. 
B) Nitrogen is light enough that it is continually escaping Earth's gravity in significant amounts, so it must be replaced by outgassing from volcanoes. 
C) Nitrogen reacts with water vapor to form various hydrocarbons. These are subducted under the crust and then outgassed from volcanoes. 
D) Bacteria process nitrate minerals and release nitrogen. Atmospheric nitrogen combines with oxygen to eventually form nitrates.

Question 3

The Mid-Atlantic Ridge is being produced by:

Accepted Answer

A) two tectonic plates pushing together and producing upthrust. 
B) volcanic upflow pushing two tectonic plates apart. 
C) the tidal flow of ocean water meeting in the mid-Atlantic. 
D) the weight of the Atlantic Ocean bending the thin crust on the seabed. 
A) two tectonic plates pushing together and producing upthrust. 
B) volcanic upflow pushing two tectonic plates apart. 
C) the tidal flow of ocean water meeting in the mid-Atlantic. 
D) the weight of the Atlantic Ocean bending the thin crust on the seabed.

Question 4

How does the temperature of Earth's atmosphere vary with height over the range 0 to 120 km?

Accepted Answer

A) It remains approximately constant at room temperature over the whole range. 
B) It always remains well below the surface temperature. 
C) It decreases and then increases 2 or 3 times. 
D) It rises steadily until it reaches a high and constant value above 120 km. 
A) It remains approximately constant at room temperature over the whole range. 
B) It always remains well below the surface temperature. 
C) It decreases and then increases 2 or 3 times. 
D) It rises steadily until it reaches a high and constant value above 120 km.

Question 5

In the 25 years between 1975 and 2000, the world's population increased from two billion to about six billion people. When is it estimated that the world's population will equal nine billion people?

Accepted Answer

A) 2015 
B) 2030 
C) 2050 
D) 2075 
A) 2015 
B) 2030 
C) 2050 
D) 2075

Question 6

The deepest parts of Earth's oceans are:

Accepted Answer

A) subduction zones, where one tectonic plate is flowing under an adjacent plate. 
B) at the two poles, near the ends of the spin axis, where tidal distortion from the Moon and Sun is least. 
C) in the centers of the oceans, where deep and fast ocean currents such as the Gulf Stream have scooped out the troughs. 
D) where large asteroids or planetoids have impacted in the past and have produced deep craters. 
A) subduction zones, where one tectonic plate is flowing under an adjacent plate. 
B) at the two poles, near the ends of the spin axis, where tidal distortion from the Moon and Sun is least. 
C) in the centers of the oceans, where deep and fast ocean currents such as the Gulf Stream have scooped out the troughs. 
D) where large asteroids or planetoids have impacted in the past and have produced deep craters.

Question 7

What caused the great mountain ranges on Earth, such as the Rocky Mountains and the Andes?

Accepted Answer

A) collisions of two tectonic plates, where one is folded into mountains while the other is thrust underneath 
B) two tectonic plates being pushed apart by molten rock that is being forced up between them 
C) heat from Earth's interior causing Earth's crust to expand and then crumple 
D) the carving of continents by ice sheets during ice ages, with the mountains left behind as "islands" in a sea of glaciers 
A) collisions of two tectonic plates, where one is folded into mountains while the other is thrust underneath 
B) two tectonic plates being pushed apart by molten rock that is being forced up between them 
C) heat from Earth's interior causing Earth's crust to expand and then crumple 
D) the carving of continents by ice sheets during ice ages, with the mountains left behind as "islands" in a sea of glaciers

Question 8

The outer core of Earth is molten, but the inner core is solid. The reason for this is that the:

Accepted Answer

A) actual temperature is below the melting point of the core material at the high pressure of the interior. 
B) lower pressure in the inner core allows the material to freeze out of the molten rock. 
C) inner core has a different composition than the outer core, with a lower melting point. 
D) temperature is lower in the inner core than in the surrounding region. 
A) actual temperature is below the melting point of the core material at the high pressure of the interior. 
B) lower pressure in the inner core allows the material to freeze out of the molten rock. 
C) inner core has a different composition than the outer core, with a lower melting point. 
D) temperature is lower in the inner core than in the surrounding region.

Question 9

What percent of incoming solar energy is reflected by Earth's surface and clouds?

Accepted Answer

A) barely more than 1% 
B) about 39% 
C) about 61% 
D) close to 100% 
A) barely more than 1% 
B) about 39% 
C) about 61% 
D) close to 100%

Question 10

Earth's magnetosphere is a region surrounding the planet:

Accepted Answer

A) that has been swept clean of all charged particles by Earth's magnetic field. 
B) into which new charged particles are prevented from entering because of Earth's magnetic field. 
C) in which the motions of charged particles are governed by Earth's magnetic field. 
D) that is dominated by the magnetic field of the Sun. 
A) that has been swept clean of all charged particles by Earth's magnetic field. 
B) into which new charged particles are prevented from entering because of Earth's magnetic field. 
C) in which the motions of charged particles are governed by Earth's magnetic field. 
D) that is dominated by the magnetic field of the Sun.

Question 11

Energy calculations that simply equate the influx of solar energy on Earth with the outflow of energy from Earth lead to a very low average equilibrium temperature for Earth, of around -18°C or -0.7°F, which is much lower than the actual average surface temperature of Earth, +14°C or 57°F. What mechanism explains this discrepancy between the simple prediction and observation?

Accepted Answer

A) kinetic energy of meteoritic material that is dissipated in the atmosphere as the particles are stopped by friction 
B) chemical action between molecules in Earth's atmosphere 
C) the greenhouse effect-the capture by gases in the atmosphere of heat radiation that would otherwise escape 
D) extra energy conducted outward from the hot interior of Earth 
A) kinetic energy of meteoritic material that is dissipated in the atmosphere as the particles are stopped by friction 
B) chemical action between molecules in Earth's atmosphere 
C) the greenhouse effect-the capture by gases in the atmosphere of heat radiation that would otherwise escape 
D) extra energy conducted outward from the hot interior of Earth

Question 12

In you were able to measure Earth's magnetic field at some time, say, 100,000 to 200,000 years ago, you would:

Accepted Answer

A) find the field to be zero because Earth's field is a relatively recent development. 
B) certainly find the field to be exactly what it is today. 
C) most likely find the field to be quite different in magnitude from what it is today. 
D) certainly find the field to be the same magnitude it is today, but exactly opposite in direction. 
A) find the field to be zero because Earth's field is a relatively recent development. 
B) certainly find the field to be exactly what it is today. 
C) most likely find the field to be quite different in magnitude from what it is today. 
D) certainly find the field to be the same magnitude it is today, but exactly opposite in direction.

Question 13

The core of Earth occupies what fraction of its radius?

Accepted Answer

A) about 25% 
B) roughly half 
C) less than 10% 
D) almost 80% 
A) about 25% 
B) roughly half 
C) less than 10% 
D) almost 80%

Question 14

Evidence for past reversals of Earth's magnetic field comes from:

Accepted Answer

A) deflected solar radiation particles trapped in polar ice. 
B) the breakup of Pangaea. 
C) magnetized rock in layers produced by seafloor spreading. 
D) various orientations of magnetic directions in the layers of Earth's mantle. 
A) deflected solar radiation particles trapped in polar ice. 
B) the breakup of Pangaea. 
C) magnetized rock in layers produced by seafloor spreading. 
D) various orientations of magnetic directions in the layers of Earth's mantle.

Question 15

The magnetopause is the part of the magnetosphere where:

Accepted Answer

A) high-energy electrons and protons collide with gases in the planet's upper atmosphere, producing fluorescence. 
B) supersonic particles in the solar wind are suddenly slowed to subsonic speeds. 
C) high-energy charged particles are trapped by the planet's magnetic field. 
D) the inward pressure of the solar wind is balanced by the outward magnetic pressure of the planet's magnetic field. 
A) high-energy electrons and protons collide with gases in the planet's upper atmosphere, producing fluorescence. 
B) supersonic particles in the solar wind are suddenly slowed to subsonic speeds. 
C) high-energy charged particles are trapped by the planet's magnetic field. 
D) the inward pressure of the solar wind is balanced by the outward magnetic pressure of the planet's magnetic field.

Question 16

What happens to the temperature in the stratosphere?

Accepted Answer

A) The temperature decreases as you move higher and farther from the warm surface of Earth. 
B) The ozone in this layer absorbs ultraviolet radiation from the Sun, so the layer is at a uniform temperature, warmer than the troposphere below it. 
C) The ozone in this layer absorbs ultraviolet radiation from the Sun; the upper parts absorb the most, and what filters through is absorbed in the lower parts. Therefore, the temperature rises with altitude in the stratosphere. 
D) The ozone in this layer absorbs ultraviolet radiation from the Sun. Convection then makes the lower parts warmer and the upper parts cooler. 
A) The temperature decreases as you move higher and farther from the warm surface of Earth. 
B) The ozone in this layer absorbs ultraviolet radiation from the Sun, so the layer is at a uniform temperature, warmer than the troposphere below it. 
C) The ozone in this layer absorbs ultraviolet radiation from the Sun; the upper parts absorb the most, and what filters through is absorbed in the lower parts. Therefore, the temperature rises with altitude in the stratosphere. 
D) The ozone in this layer absorbs ultraviolet radiation from the Sun. Convection then makes the lower parts warmer and the upper parts cooler.

Question 17

Earth's magnetic field is generated by:

Accepted Answer

A) permanent magnetism in Earth's crustal rocks. 
B) electric currents in Earth's core. 
C) electric currents in Earth's mantle. 
D) the flow of electrons and ions in Earth's magnetosphere. 
A) permanent magnetism in Earth's crustal rocks. 
B) electric currents in Earth's core. 
C) electric currents in Earth's mantle. 
D) the flow of electrons and ions in Earth's magnetosphere.

Question 18

Suppose Earth were put into orbit around a cool star (cooler than our Sun) at the right distance for our oceans to remain liquid so that life could still exist but the star emitted no UV radiation. Each of the following statements gives a consequence of this change, except one. Which would not be a consequence of this change?

Accepted Answer

A) Our ozone layer would become larger. 
B) Our magnetosphere would disappear. 
C) The temperature in the stratosphere would decrease. 
D) We would be closer to the star than we are to our present Sun. 
A) Our ozone layer would become larger. 
B) Our magnetosphere would disappear. 
C) The temperature in the stratosphere would decrease. 
D) We would be closer to the star than we are to our present Sun.

Exam 9: The Living Earth

The Van Allen belts are:

How stable is the nitrogen in Earth's atmosphere?

The Mid-Atlantic Ridge is being produced by:

How does the temperature of Earth's atmosphere vary with height over the range 0 to 120 km?

In the 25 years between 1975 and 2000, the world's population increased from two billion to about six billion people. When is it estimated that the world's population will equal nine billion people?

The deepest parts of Earth's oceans are:

What caused the great mountain ranges on Earth, such as the Rocky Mountains and the Andes?

The outer core of Earth is molten, but the inner core is solid. The reason for this is that the:

What percent of incoming solar energy is reflected by Earth's surface and clouds?

Earth's magnetosphere is a region surrounding the planet:

In you were able to measure Earth's magnetic field at some time, say, 100,000 to 200,000 years ago, you would:

The core of Earth occupies what fraction of its radius?

Evidence for past reversals of Earth's magnetic field comes from:

The magnetopause is the part of the magnetosphere where:

What happens to the temperature in the stratosphere?

Earth's magnetic field is generated by:

Astronomy and the Universe

Knowing the Heavens

Eclipses and the Motion of the Moon

Gravitation and the Waltz of the Planets

The Nature of Light

Optics and Telescopes

Comparative Planetology I: Our Solar System

Comparative Planetology II: the Origin of Our Solar System

Our Barren Moon

Mercury, Venus, and Mars: Terrestrial, yet Unique

Jupiter and Saturn: Lords of the Planets

Jupiter and Saturns Satellites of Fire and Ice

Uranus, Neptune, Pluto, and the Kuiper Belt: Remote Worlds

Asteroids, Comets, and Impacts

Our Star, the Sun

The Nature of the Stars

The Birth of Stars

Stellar Evolution: on and After the Main Sequence

Stellar Evolution: The Death of Stars

Stellar Remnants: Neutron Stars and Black Holes

Our Galaxy

Galaxies

Quasars and Active Galaxies

Cosmology: The Origin and Evolution of the Universe

Exploring the Early Universe

The Search for Extraterrestrial Life

Filters