Practice Test: Earth and Space Science (74)

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Question Number	Your Response	Correct Response (show answershide answers)	Related Objectives and Rationale (show objectives & rationaleshide objectives & rationales)
1	Answer to question 1	D	Objective 001 Response D is correct because, as matter accelerates towards the event horizon of the black hole, its temperature increases due to the gravitational and frictional forces that it experiences. As the temperature increases, the material emits high amounts of radiation on the electromagnetic spectrum, producing the glow that is detectable at the visible light and X-ray range of the spectrum. Dark matter is never in the visible spectrum by definition (Incorrect Response A). Its presence is only detectable through its gravitational interactions. While protostar formation can be triggered by the compression wave resulting from the supernova that may lead to a black hole, the area near the black hole is much more likely to be pulling matter apart than compressing it (Incorrect Response B). Quasars are thought to be the nuclei of newly forming galaxies, but stars and galaxies aren't thought to have formed until a few hundred million years after the Big Bang (Incorrect Response C).
2	Answer to question 2	D	Objective 001 Response D is correct because the electrons within an atom orbit are at fixed distances from their nuclei. These distances are known as orbitals. When exposed to enough energy, the electrons can "jump" to a higher orbital. Eventually electrons within an atom release their absorbed energy to return to their ground state. Since each element has a different arrangement of electrons, the release of energy will produce a distinct fingerprint of electromagnetic radiation. This fingerprint allows scientists to determine the chemical composition of a star. While other subatomic particles, like neutrinos, are released during nucleosynthesis, only electrons are responsible for producing the electromagnetic radiation used in spectroscopy (Incorrect Response A). The energy released by the electrons of an atom, not the energy of nuclear fusion, is what produces the characteristic absorption or emission spectrum (Incorrect Response B). Elements are the largest unit formed within stars. Temperatures are too high for atoms to form stable bonds with each other to create molecules (Incorrect Response C).
3	Answer to question 3	B	Objective 001 Response B is correct. In the demonstration, the spandex represents the fabric of space-time. Massive objects have a high gravitational pull and warp space-time around them. The marble, representing a photon, has its path altered as it passes through the area of warped space-time. The billiard ball and marble are not joining (Incorrect Response A) or collapsing together (Incorrect Response D). If centripetal forces were dominating (Incorrect Response C), the marble would be forced to the edges of the spandex.
4	Answer to question 4	A	Objective 001 Response A is correct because the discovery of cosmic background radiation coming from all directions in space provided the first observational evidence supporting the Big Bang theory of the universe. The Big Bang theory suggests the universe started with a massive explosion and rapid expansion. The discovery of a black hole at the center of the Milky Way (Incorrect Response B) was based on observations of an intense radio source at the middle of the Milky Way galaxy and is not related to this work. The homogeneity and absolute size of the universe (Incorrect Response C) is still a matter of conjecture and study. The bending of light by large gravitational fields (Incorrect Response D) was first observed in 1919 during a solar eclipse but had been proposed by Isaac Newton and later calculated by Albert Einstein.
5	Answer to question 5	C	Objective 001 Response C is correct because neutron stars are the remnant stars that remain following the collapse and supernova eruption of a massive star. The majority of known neutron stars are pulsars, emitting regular and rapid radio pulses as they spin at very high speeds. Neutron stars conserve the angular momentum of the original star they formed from, and because they are so small and dense, their rotational speed is very great. An expanding planetary nebula (Incorrect Response A) would not be a likely source of rapidly pulsing radio signals from a neutron star. Black holes do emit fluctuating radio signals as they consume mass (Incorrect Response B), but not in the regular rapid way that pulsars do. An eclipsing binary star system (Incorrect Response D) changes brightness as one star of the pair moves in front of the other, but the regular change in brightness would be much slower than the pulses emitted by a rapidly pulsating neutron star.
6	Answer to question 6	C	Objective 001 Response C is correct because variations in the density of space support the theory that a period of rapid inflation of the universe occurred fractions of a second into the Big Bang. Astronomers inferred that the universe rapidly expanded at the start of the Big Bang during a period of cosmic inflation. At the start of this brief period of inflation, quantum fluctuations occurred in the closely packed universe that later became the variations in density seen in today's greatly expanded universe. The proportion of elements in asteroids (Incorrect Response A) provides information on the solar system's formation, not the inflationary period. The motion of receding galaxies (Incorrect Response B) provides evidence of the universe's ongoing expansion but not of the earliest inflationary period of its formation. Energy released from nuclear fusion (Incorrect Response D) supports understanding of stellar evolution but not the conditions hypothesized to have existed during cosmic inflation.
7	Answer to question 7	D	Objective 002 Response D is correct because in the northern hemisphere the position of the Sun at solar noon is lowest in the sky on the winter solstice: December 21. The lower the position of the Sun, the more of the light a body or object will be blocking at a given time. The greater the amount of light that an object blocks, the larger the shadow will be. In the northern hemisphere, March 21 (Incorrect Response A) is the vernal equinox, and a person's shadow will be equal in length on this date as on September 21 (Incorrect Response C), which is known as the autumnal equinox. June 21 (Incorrect Response B) is the summer solstice. At solar noon, the Sun will reach its highest point overhead during the entire year and the shadows cast will be the smallest.
8	Answer to question 8	A	Objective 002 Scientists currently think that life requires an environment where there is liquid water and relative protection from catastrophic disasters. The luminosity of a star, or the amount of energy that it releases at a time, will determine how close a planet needs to be in order to support these conditions (Correct Response A). Low luminosity stars will have a habitable zone that lies relatively close to the star, and the stars tend to be relatively stable and long-lived. The habitable zone around high-luminosity stars will generally be farther away, and planets orbiting those stars have a shorter time frame to evolve life before the star reaches the end of its life. In the current search for life, scientists are most concerned with conditions at the surface and immediate subsurface. The overall composition of the planet matters somewhat since it's thought that there is likely to be life on planets with liquid water at the surface, but the composition of the core matters much less (Incorrect Response B). At the surface and in the atmosphere, oxygen can be a product of living organisms, but there are many microbial organisms that do not require oxygen for their biological processes (Incorrect Response C). In the search for habitable planets, the galaxy is too large of a spatial scale to consider when looking at whether a planet could support life (Incorrect Response D). The conditions within a galaxy vary too much to make an accurate determination of an individual planet's habitability.
9	Answer to question 9	B	Objective 002 Response B is correct because the size of the circle of light produced will correspond to how close the light source is to the globe. When the globe is tilted towards the flashlight, it is closest to the light and the circle will be the smallest (Incorrect Response C). When the globe is tilted away from the flashlight, it is farthest from the light and the circle will be the largest. At a 90 degrees angle, the circle's size will be in between the two measurements. Since tilting the globe will change the size of the circles, the three alignments will not result in the same size of circles (Incorrect Responses A and D).
10	Answer to question 10	A	Objective 002 There is a high tide on the side of Earth facing the Moon, but there is also a high tide on the side of Earth facing away from the Moon, and the underlying reason for the formation of this opposite-side high tide is that the Moon's gravitational pull varies across Earth (Correct Response A). It creates one tidal bulge where the Moon's gravitational pull is strongest and one on the opposite side, where the Moon's gravitational pull is weakest. Frictional interactions between ocean water and the ocean floor (Incorrect Response B) can affect local tide cycles but not global-scale tidal phenomena. The Sun plays a supporting role in ocean tides (Incorrect Response C); however, its effects are much smaller than the Moon's in forming the tidal bulge that faces away from the Moon. Earth's axial tilt relative to the Moon (Incorrect Response D) is not a major factor in the formation of ocean tides.
11	Answer to question 11	C	Objective 002 Lunar eclipses occur when the Moon moves across the Sun, producing a shadow on Earth. A lunar eclipse can only occur when the Moon is in a direct line between the Sun and Earth. Since the Moon's orbit of Earth is tilted 5 degrees relative to Earth's orbital plane (the ecliptic), this lineup can only occur two or three times a year and not each time the Moon completes its orbit of Earth (Correct Response C). Neither Earth's axial tilt relative to the plane of its orbit (Incorrect Response A) nor the different orbital periods of Earth and the Moon (Incorrect Response B) affect the relationship between Earth, the Moon, and the Sun that produces lunar eclipses. The Moon's orbital period (27 days) is much longer than Earth's 24-hour rotational period (Incorrect Response D), but that difference is not responsible for the rarity of lunar eclipses each year.
12	Answer to question 12	A	Objective 002 Newton's first law of motion, the Law of Inertia, states that an object either remains at rest or continues to move at a constant speed in the same direction, unless acted upon by an external force. Earth's gravitational field exerts an external force on the Moon, pulling it toward Earth. This force deflects the Moon from moving in a straight line tangent to the curved path of its orbit (Correct Response A). Although the Moon's orbital path, velocity, and rotation (Incorrect Response B) are affected by its inertia and rotational inertia, the interaction of these factors does not summarize Newton's first law. The Moon does accelerate as it falls toward Earth during its orbit (Incorrect Response C), but the gravitational interaction that causes the acceleration does not summarize Newton's first law any more effectively than do the concepts of weight and centripetal force (Incorrect Response D).
13	Answer to question 13	D	Objective 003 During the first 500 to 600 million years of the planet’s existence, Earth was still subject to heavy bombardment from extraplanetary objects, including asteroids and comets. Protected deep in the oceans, hydrothermal vents would have been a relatively sheltered environment for the origin of life (Correct Response D). Conditions at vents are not conducive to life as we know it on the surface. Since the earliest forms of life were likely anerobic, oxygen would have been toxic to them (Incorrect Response A). Life-forms at hydrothermal vents rely on sulfurous compounds (Incorrect Response B) released from within the Earth using the process of chemosynthesis, rather than photosynthesis (Incorrect Response C) to gain the energy they need.
14	Answer to question 14	C	Objective 003 Response C is correct. The Devonian period extended from about 400 million years ago ( M A ) to 360 M A . During this time period, there was a tremendous amount of adaptive radiation occurring among fish. So much so that the period is known as the Age of the Fishes. Reptiles, dinosaurs, and early mammals are all descendants of one of the groups of lobe-finned fish that evolved during the Age of Fishes. By the time of the Cretaceous period (Incorrect Response A), 145 to 66 M A , insects had been around for at least 300 million years. The Devonian was not the first time that organisms on Earth experienced such evolutionary diversification. The Cambrian period (Incorrect Response B) is often called the "Cambrian Explosion" because of the rapid evolution of many forms of life. However, this occurred primarily in the ocean, as there was still very little life on land at this point. The Triassic (Incorrect Response D), 250 to 200 M A , saw the rise of reptiles and early dinosaurs.
15	Answer to question 15	C	Objective 003 Response C is correct. If a species is not found in the fossil record in a given time frame, it's likely that the species either did not exist at that time because it had not yet evolved or it was already extinct. With this information, we can conclude that stratum 3 comes first because it is the first appearance of species C and species D, while species A and species B have not appeared yet. Species generally will not disappear and then reappear in the fossil record later. Therefore, the next layer that should appear is stratum 2. This is because placing either 1 or 4 instead of stratum 2 next would mean that a species disappears and reappears (Incorrect Responses A and B). Species B must first appear before it can be labeled common in appearance (Incorrect Response D), so the order must be stratum 4 and then, finally, stratum 1 as the youngest layer.
16	Answer to question 16	A	Objective 003 Response A is correct because a large river will erode the rock down through the stratigraphic column. In this situation, the strata in question were in place before the river formed and the river can only cut through pre-existing layers. The Law of Lateral Continuity states that strata are deposited in continuous layers extending in all directions, so if erosion removes layers in a part of the landscape, geologists can correlate the layers on either side of the divide. The other laws and principles would not be able to give the same information. The principle of cross-cutting relationships can be used to determine the age of rocks relative to the intrusive basalt dike (Incorrect Response B). Geologists can use their knowledge of unconformities (the absence of layers due to erosion) to help infer how and when erosion may have occurred (Incorrect Response C). The principal of original horizontality will help explain the history of layers that have been folded or forced out of their original orientation (Incorrect Response D).
17	Answer to question 17	D	Objective 003 During the Appalachian orogeny, what is now North America experienced a collision event. This caused the existing rocks to bend and fold, leaving behind the folded pattern that can be seen in the Appalachian Mountains today (Correct Response D). The coastal lowlands of Rhode Island are moraines that were the result of glaciers retreating at the end of the last ice age (Incorrect Response A). While there are high quantities of granite in Massachusetts, much of the parent rock was formed over a billion years ago as a part of supercontinent formation (Incorrect Response B). Additionally, the visibility of the rock layers in the Connecticut River Valley is a result of a rift that formed during the breakup of Pangaea, where landmasses were moving apart rather than colliding (Incorrect Response C).
18	Answer to question 18	C	Objective 003 Response C is correct because strike and dip measurements are the conventional data that a geologist collects to report a geologic layer's bedding orientation in terms of the cardinal directions and the horizontal plane. The depth below the land surface of the limestone strata exposed in the road cut (Incorrect Response A) is not relevant information for reporting the bedding orientation of the limestone strata. An imaginary vertical plane is not referenced in recording the orientation of geologic strata (Incorrect Response B). While the thickness of a limestone bed is recorded in the field if possible, the original orientation of the bedding (Incorrect Response D) is an interpretation of geologic history that is not typically part of mapping the orientation of geologic strata.
19	Answer to question 19	D	Objective 003 Response D is correct because the only statement that can be confirmed by the relationships depicted in the geologic cross section is that the basalt dike was intruded after the sandstone was deposited. Since the dike intrudes the batholith, the intrusion of the dike must have happened after the sandstone was deposited as well. The cross section does not indicate when the faulting occurred relative to the intrusion of the dike (Incorrect Response A), and since the granite does not intrude the breccia, it is impossible to say if it occurred before or after the breccia deposition (Incorrect Response B). Since the breccia is offset by the fault, the faulting could not have occurred until after the shale was deposited (Incorrect Response C).
20	Answer to question 20	D	Objective 004 Response D is correct because much of the interior heat of the earth is produced by radioactive decay, but some of the energy originated in the formation of the planet. During the early days of our solar system, Earth formed through the accretion of smaller objects. As these bodies collided, the friction produced a large quantity of heat that is still dissipating billions of years later. There are other ways for heat to be produced within the planet. Other bodies in our solar system, such as Jupiter's moon, Io, do experience significant tidal heating (Incorrect Response A), and there is heat produced through the friction between the inner and outer core (Incorrect Response B), but neither of these sources is a significant contributor to the heat of Earth. Interactions between the inner and outer core are thought to be responsible for our magnetic field, but those interactions are not a major source of heat energy (Incorrect Response C).
21	Answer to question 21	A	Objective 004 Response A is correct. When the Earth was still forming, it was too hot to solidify due to continual impacts by objects within the solar system. The colliding material, including planetesimals, was of similar density and composition to early Earth (Incorrect Response B). Differences in density lead to the separation of the earth into layers. Since the earth was molten, the denser material was able to sink to the center. The convection currents (Incorrect Response C) and the centrifugal forces (Incorrect Response D) were not strong enough to overcome the differences in density.
22	Answer to question 22	A	Objective 004 Response A is correct because during the late Paleozoic, the supercontinent Pangaea was forming. What is now southwest Africa, southeast South America, southern India, northern Australia, and Antarctica were conjoined in the southern hemisphere. Glaciation events would have occurred across southern Pangaea, leaving behind similar glacial striations on the rocks. It is unlikely that the markings would have been caused simultaneously in separate locations on the globe (Incorrect Response B). During this time, the average global temperatures were significantly higher than they are today (Incorrect Response C). This would not be conducive to extensive glacier formation (Incorrect Response D).
23	Answer to question 23	C	Objective 004 Response C is correct because the features that result from plate interactions depend on the nature of the interactions. For example, there are features, like volcanoes, that are unlikely to form at transform boundaries. The size of a plate (Incorrect Response A) is not as important as the direction of a plate's movement for determining features. There are some small plates, like the Juan de Fuca plate, that have significant impacts on the surrounding plates despite their small size. The rate of movement (Incorrect Response B) will impact the intensity of the interaction but does not determine whether a boundary will result in trenches or mountains. Seismic activity can be useful for determining the boundaries of plates because they occur wherever geologic stress builds, but it is not useful for distinguishing between types of plate boundaries (Incorrect Response D).
24	Answer to question 24	A	Objective 004 Earthquakes generate P waves (compressional waves), S waves (shear waves), and surface waves. S waves penetrate Earth's crust and mantle; however, they do not travel through liquids so they do not penetrate the liquid outer core (Correct Response A). Seismologists examining seismic data collected from major earthquakes noticed a shadow zone where S waves were absent on the opposite side of the planet from where the seismic waves were generated. This led to the conclusion that the outer core was liquid. Although P and S waves are reflected differently from solids (Incorrect Response B), this difference does not provide information on the physical character of the outer core. P waves can pass through high-temperature materials (Incorrect Response C). While P and S waves are refracted at different angles from irregular surfaces (Incorrect Response D), this fact does not provide evidence of the liquid character of the outer core.
25	Answer to question 25	D	Objective 004 Response D is correct because the magnetic orientation of ferromagnetic minerals in ocean-floor basalts demonstrated that oceanic lithosphere was moving apart as new basalt was generated at ocean spreading centers. This provided a mechanism to help explain two important components of plate tectonic theory: the movement of tectonic plates and the formation of new oceanic crust. Astronomical evidence and not geologic evidence indicates that, as a result of gravitational interactions, Earth's rotational velocity is decreasing very slowly over time and is not stable (Incorrect Response A). Because ocean crust is recycled at subduction zones, ocean-floor basalt is typically younger than 200 million years old and therefore does not provide evidence of Earth's age (Incorrect Response B). The physical character of the upper mantle was not determined through analysis of the magnetism of ocean-floor basalt (Incorrect Response C). The upper mantle is solid and together with oceanic crust constitutes oceanic lithosphere.
26	Answer to question 26	D	Objective 004 Response D is correct because scarps and sag ponds are typical features associated with strike-slip faults. As the land surrounding the faults is offset by lateral movement along the fault, some vertical movement of the land on either side of the fault creates fault scarps. Sag ponds are small water bodies that occupy depressions created where fault movements have created depressions that impound drainage. Hanging valleys and tarns (Incorrect Response A) and kame terraces and eskers (Incorrect Response B) are landforms associated with glaciers, not faulting. Horst and graben (Incorrect Response C) refer to landforms where normal faulting has pushed some blocks of crust upward (horst) and caused some blocks to drop down (graben). Horst and graben features are not typically associated with strike-slip faults.
27	Answer to question 27	D	Objective 004 Response D is correct because the Atlantic Ocean formed as a consequence of the breakup of Pangaea. The breakup occurred in several stages over millions of years, beginning 175 million years ago in the Middle Jurassic. Pangaea began to break into separate continents as a consequence of geologic rifting of continental crust. The rift developed into a divergent plate boundary that pushed the plates apart, eventually forming the Atlantic Ocean basin. Erosion caused by continental glaciations (Incorrect Response A) is not a process capable of initiating the formation of a major ocean basin, and no continental glaciations occurred during the Middle Jurassic. Subduction (Incorrect Response B) occurs along convergent plate boundaries and could not have initiated the formation of the Atlantic Ocean basin. The development of a syncline to explain the initial formation of the Atlantic Ocean basin (Incorrect Response C) is not consistent with modern plate tectonic theory.
28	Answer to question 28	A	Objective 004 Response A is correct because passive plate margins of continents, such as the eastern coast of the United States, are composed of continental crustal rocks covered in thick sedimentary deposits. A geologic platform is the part of a continent covered by horizontal or gently tilted, mostly sedimentary, strata. Along passive plate margins, these deposits make up the thick sediments of the continental shelf. Forearc basins (Incorrect Response B) form in association with subduction zones at active and not passive plate margins. An accretionary wedge (Incorrect Response C) is also associated with subduction zones at convergent plate boundaries where an oceanic plate is subducted beneath a continental plate. Passive continental plate margins are not associated with active fault zones (Incorrect Response D) because the continental crust at these margins is typically not being fractured or compressed by tectonic forces.
29	Answer to question 29	D	Objective 005 Response D is correct because monadnocks are the remains of uplifted features. As the softer sedimentary surrounding rock is eroded, the more resistant rock remains. Monadnocks form as the result of sedimentary, not volcanic, features (Incorrect Response A). Terminal moraines are composed of rocks and sediment (Incorrect Response B). They would not form smooth, treeless summits. Lastly, the rocks that form a mountain chain are typically not so varied that erosion would create a single, isolated summit (Incorrect Response C).
30	Answer to question 30	C	Objective 005 Response C is correct because orthoclase feldspar is a 6 on the Mohs hardness scale and pure quartz is a 7. They are both the defining mineral for that value on the scale. Any mineral will be able to scratch another mineral with a lower hardness and will be able to be scratched by minerals with a higher hardness. Since the unknown mineral can scratch feldspar, its hardness must be greater than 6. Since it cannot scratch the quartz, its hardness must be less than 7. The only choice with a number between 6 and 7 is Response C, 6.5. If the unknown mineral had a hardness below 6, it would not be able to scratch either the feldspar or the quartz (Incorrect Responses A and B). If the unknown mineral had a hardness of 8.5 (Incorrect Response D), it would be able to scratch both the orthoclase feldspar and the quartz.
31	Answer to question 31	C	Objective 005 Response C is correct because mass wasting is the downward movement of rocky material and debris, primarily under the force of gravity. A landslide is the only example where the material is rocky and the primary cause of movement is gravity. An avalanche (Incorrect Response A) moves primarily snow and ice, not rock. While the movement of water in a stream (Incorrect Response B) is due to gravity, it is the movement of the water over the rock that causes erosion. A dust storm (Incorrect Response D) is moving rocky material, typically in the form of sand and fine particles, but the force is wind, not gravity.
32	Answer to question 32	D	Objective 005 Response D is correct because the declination value that is listed on topographic maps refers to the magnetic declination that represents the difference between true north and magnetic north as measured by a compass. Declination does not provide information on the relief shown on a map (Incorrect Response A). Latitude and longitude on a flat topographic map (Incorrect Response B) are unrelated to declination and do not need to be adjusted to accommodate Earth's curved surface. The numeric and graphic scale given on a topographic map (Incorrect Response C), and not the declination, are used to estimate distances on the map.
33	Answer to question 33	B	Objective 005 Response B is correct because lichens, plant roots, and fungi can produce weak acids to break down rock. This is an important part of weathering that makes the minerals in rocks available for use by these organisms and others. Molecular water that exists in the crystal structure of some minerals is bound to the minerals and typically not available for biological activity (Incorrect Response A). These organisms cannot extract minerals directly from rocks through osmosis because osmosis is the diffusion of water (Incorrect Response C), and while salts can cause chemical weathering, they are not produced by these organisms (Incorrect Response D).
34	Answer to question 34	D	Objective 005 Response D is correct because water expands its volume as it freezes. This property causes water that has moved into rock fractures and crevices to push against the rock when temperatures drop below freezing. The pressure created by the expansion of water is an important cause of mechanical weathering in regions where temperatures drop below freezing. The slight change in water's density and volume as it warms above freezing (Incorrect Response A) is not a major factor in mechanical weathering. Water's high specific heat (Incorrect Response B) and relatively high surface tension (Incorrect Response C) are not primarily responsible for water's ability to mechanically weather rock.
35	Answer to question 35	B	Objective 005 Response B is correct because as an eastward-flowing longshore current carries sediment along the coastline depicted in the diagram, the current slows where it flows across the bay inlet. The current's reduced velocity causes deposition of sand at the bay mouth. Wind certainly redistributes coastal sand, but the sand that forms spits arrives primarily through deposition from the prevailing longshore current (Incorrect Response A). Tidal currents tend to be stronger at the mouth of a bay and not weaker, so they tend to work against the formation of spits (Incorrect Response C). If ocean waves were flowing toward the west in the diagram, the sand spit would be forming on the east side of the bay mouth (Incorrect Response D). Although the tidal currents can modify the spit, they would not move the sand across the bay mouth to its west side.
36	Answer to question 36	C	Objective 005 Response C is correct because graded bedding in sedimentary rock strata is the change in sediment grain size from the base of the bed to the top. Normal graded bedding is the most common and shows coarser grain size at the bottom with increasingly finer sediments toward the top of the bed. This kind of bedding is often associated with sedimentary rocks that formed in marginal marine environments, such as coastal deltas and turbidity flows. Desert depositional environments (Incorrect Response A), such as a dune and high-energy beach deposits (Incorrect Response B), are more likely to exhibit cross-bedding with little change in grain size. Alluvial fan sediments (Incorrect Response D) are typically deposited rapidly during flash floods. As a consequence, they are usually composed of heterogeneous sediments that have poorly defined bedding or no bedding at all.
37	Answer to question 37	A	Objective 005 Response A is correct because a deep-ocean trench is an offshore environment with very still water. Shale is a sedimentary rock that forms by compaction of fine-grained sediments that have slowly settled out of very slow-moving water. Of the response choices, shale is the only likely sedimentary rock that would be expected to have formed in such a depositional environment. Sandstone (Incorrect Response B) is typically associated with higher-energy depositional conditions, such as beaches and rivers. Breccia (Incorrect Response C) is a sedimentary rock composed of angular fragments cemented together with finer-grained sediments and is most often associated with high-energy depositional environments, such as desert flash floods or sheetwash deposits from steep hillsides. Limestone (Incorrect Response D) is a carbonate sedimentary rock that most often forms from the shells of marine organisms in relatively shallow and warm marine environments and is not associated with deep-ocean trench depositional environments.
38	Answer to question 38	A	Objective 006 Response A is correct because water is a polar molecule, which means that one end of the molecule is more positively charged than the other. The positive side of one molecule and the negative side of another are attracted to one another. The tendency of water molecules to be cohesive means that they are typically found grouped together, rather than as isolated molecules. The phenomenon that is best explained by this property is the formation of rain droplets from individual molecules. Rivers flow in channels (Incorrect Response B) because of the topographical features of the area. The other phenomena rely on different properties of water. Density differences (Incorrect Response C) are not strongly related to cohesion, and retaining heat more efficiently than land (Incorrect Response D) is due to water's specific heat.
39	Answer to question 39	C	Objective 006 Response C is correct because water molecules form a web of weak hydrogen bonds, allowing objects of higher density to remain at the surface, rather than sinking. The best example of this phenomenon is the water strider insect remaining on the surface of a still pond. The water strider is denser than the water, but as long as there is not enough force to break the hydrogen bonds, it will stay on the surface. Surface tension is a property of liquids, so it could apply to the droplets that make up a cloud (Incorrect Response A) but not the cloud as a whole. Ice floats because it is less dense than liquid water, not because of surface tension, and it forms at the edges because those areas change temperature more rapidly (Incorrect Response B). Water does not flow across the landscape in sheets (Incorrect Response D) because the path of the water is determined by the topography, gravity, and friction, not to water's surface tension.
40	Answer to question 40	A	Objective 006 Response A is correct because if two streams have similar discharge rates and gradients, the main factor that will affect their discharge rate after a storm will be the surrounding area's rate of infiltration. Infiltration is the process by which surface water seeps into the ground. Highly porous surfaces, like sand, will have a high rate of infiltration while surfaces with a low porosity, like pavement, will have a low rate of infiltration. During the first few hours following a storm event, much of the water will be flowing over the land. After that period, infiltration increases. Looking at the data table, at the four-hour mark the discharge rate is much higher for stream 1 than stream 2, which indicates that the area has reduced infiltration. Rocky and sandy stream beds likely have similar porosity (Incorrect Response C), so that is unlikely to explain the reduced infiltration rates. The data are tracking a percent change, so the height of the water table before the storm (Incorrect Response B) should be proportional. If there were significant watershed size differences between stream 1 and stream 2, those differences would likely be reflected in the discharge at the 2-hour mark and later in the 12-hour mark. Since those rates are similar, it is unlikely that they represent watersheds with significantly different drainage areas (Incorrect Response D). The most likely explanation for this is that stream 1 is flowing through a suburban environment where many surfaces are covered by buildings and pavement, making infiltration much more difficult than more exposed surfaces like those found in forests.
41	Answer to question 41	D	Objective 006 The residence time, or the amount of time that a molecule of water spends in a river, will largely depend on how fast that water molecule can move from its entry point to the exit point of the river. The faster the river flows, the shorter the residence time, and with a steeper gradient of the river, the river will flow faster (Correct Response D). The mean annual volume (Incorrect Response A) and the number of tributaries (Incorrect Response B) can indicate how much water flows in the river, but they do not indicate how fast it is moving. The substrate that the river is flowing over (Incorrect Response C) is determined by the geology of the area, and the material of the riverbed depends on the speed of flow, not the other way around.
42	Answer to question 42	D	Objective 006 Response D is correct because if there is an increase of evaporation from the Arctic Ocean, then there will be more moisture in the local atmosphere that will eventually fall as precipitation. The precipitation would not likely be more acidic (Incorrect Response A) since acid rain is caused primarily by pollutants in the atmosphere. Increasing evaporation without an equivalent increase in precipitation could increase the salinity of the ocean, not decrease it (Incorrect Response B). Decreasing the amount of winter snowfall would decrease the regional albedo, not increase it (Incorrect Response C).
43	Answer to question 43	A	Objective 006 Albedo is a measure of the reflectivity of a surface. Ice and snow have a high albedo, while dark rocks have a lower albedo. If there is less ice and snow with more dark rock exposed, the albedo of the surface in that area will decrease. As it reflects less and less light energy, the rocks will warm, causing further melting of ice and snow (Correct Response A). The clouds that form will typically release their water on the windward side of mountains, not the leeward side (Incorrect Response B). The extra meltwater will generally flow downstream, but it can get pent up behind an obstruction. The release of the water can be gradual and is rarely catastrophic (Incorrect Response C). The extra water vapor will not stay in place (Incorrect Response D); rather, it will travel along the prevailing wind patterns.
44	Answer to question 44	B	Objective 006 Scientists examining the effects of acid rain are going to be looking at the pH of the lake water. One of the factors that is likely to affect the pH of an individual lake is the type of rock that is below the body of water, since different rock strata will lead to variation in the dissolved minerals available to buffer the acidity (Correct Response B). This is easier to account for than the average pH of the rivers (Incorrect Response A) since pH can vary over the course of a year in ways that are quantifiable but not controllable by researchers. Water clarity (Incorrect Response C), or turbidity, is also not ideal as an independent variable because it is not easily manipulated by researchers. Biodiversity (Incorrect Response D) is a much better dependent variable than independent variable because it will likely change as a result of the acidity of the lakes.
45	Answer to question 45	B	Objective 006 Response B is correct because standard deviation is a measure of the variability of a data set. It is the square root of the variance of the data set, where the variance represents how spread out a data set is from the mean. In this way, standard deviation is useful for determining the variability of a river's discharge over a period of time. The median (Incorrect Response A) measures the middle value of a data set, not its variability, while the mode (Incorrect Response C) is the most common value in the data set. The arithmetic mean (Incorrect Response D) is the average of the data set, a value that the hydrologists have already calculated and that does not measure variability.
46	Answer to question 46	A	Objective 006 Response A is correct because unlike most other substances, water becomes less dense as it is cooled to form ice. The rigid crystal structure of ice makes it less dense than liquid water because molecules in liquid water are constantly changing position and maximizing hydrogen bonding between water molecules. This allows liquid water molecules to pack more closely than water molecules that are frozen into a crystal structure. Viscosity is a measure of the internal friction of a substance; the viscosity of water (Incorrect Response B) is not a factor directly responsible for the relatively low density of ice. Although the water molecules in ice are constantly vibrating (Incorrect Response C), it is not this characteristic of ice that is responsible for its low density. The high heat capacity of liquid water (Incorrect Response D) results from the hydrogen bonding between water molecules and is not directly the cause of ice's low density.
47	Answer to question 47	D	Objective 006 Response D is correct because the depletion of the High Plains Aquifer has been caused primarily by water withdrawals for agriculture in a geographic region that does not have sufficient precipitation to recharge the aquifer. Much of the water in the aquifer entered the aquifer during the last ice age when precipitation in the region was greater. There is limited forest cover in the semi-arid High Plains so changes in forest cover (Incorrect Response A) are not responsible for the depletion of the aquifer. Although periods of drought have not benefited the aquifer in recent years (Incorrect Response B), recent climate change is not the primary cause of the aquifer's depletion. Soil compaction (Incorrect Response C) has likely played a very small role in reducing recharge rates in the area; this is not a significant factor when compared with the tremendous water withdrawals for agriculture.
48	Answer to question 48	A	Objective 006 Response A is correct because the cold, high salinity water of the North Atlantic has the greatest density because higher salt concentration and cold temperature increase water's density. Below 4 degrees Celsius , the density of water drops slightly, but most of the water of the North Atlantic is above that temperature. As a result of this relationship between density and the salinity and temperature of water, warm high-salinity water (Incorrect Response B) will have a lower density than cold high-salinity water. Cold water with moderate salinity (Incorrect Response C) will have a lower density than cold water with high salinity, and warm water with relatively low salinity (Incorrect Response D) will also be less dense than cold water with high salinity.
49	Answer to question 49	C	Objective 006 Response C is correct because the slight decrease in salinity of North Atlantic surface waters has reduced the water's density. This change likely results from increased freshwater influx from Greenland's melting ice sheet. A substantial drop in salinity will reduce the rate at which North Atlantic surface waters sink. Since this sinking water pulls the Gulf Stream's warm water northward as part of the ocean's thermohaline circulation, this change could alter the region's climate. Salinity does affect water pH (Incorrect Response A), but it is not the primary concern of scientists studying changes in salinity in the region. The change in salinity would be unlikely to directly affect precipitation in the region (Incorrect Response B), and although it would increase the formation of sea ice (Incorrect Response D) in far northern areas, this is not a concern for scientists studying the phenomenon.
50	Answer to question 50	D	Objective 006 Response D is correct because deep-ocean currents are part of the ocean's thermohaline circulation, which is driven by temperature and salinity gradients in the oceans. Deep-ocean currents are not affected by surface wave energy (Incorrect Response A), as the energy of surface waves dissipates rapidly with depth. The Moon's gravitational pull (Incorrect Response B) is a major driver of ocean tide cycles, but it does not have a significant effect on deep-ocean currents. Although Earth's orbital and rotational motion affects ocean circulation (Incorrect Response C), it is not a primary driver of the thermohaline circulation that produces deep-ocean currents.
51	Answer to question 51	C	Objective 007 Response C is correct because the temperature inversion seen in the stratosphere is due to the ability of ozone layer to absorb the shortwave, ultraviolet (UV) radiation from the Sun and reradiate it as heat. The higher portions of the stratosphere receive the most UV radiation and therefore heat up the most. If clouds were responsible for heating the stratosphere by reflecting solar radiation (Incorrect Response A), then the temperature profile would likely show a decrease in temperature, rather than an increase, with increasing height. Since the warmest part of the atmosphere is at the upper part of the stratosphere, there are no major differences in heat that would cause convection currents (Incorrect Response B). While the mesosphere is thinner, it is also colder than the stratosphere because the amount of incoming solar radiation is not as important as what mechanisms exist to retain energy (Incorrect Response D).
52	Answer to question 52	B	Objective 007 Response B is correct because the labels U V A , UVB, and UVC represent different, increasingly energized bandwidths in the ultraviolet portion of the electromagnetic spectrum. The primary reason that the majority of U V radiation that makes it to the surface is U V A is the fact that UVB and UVC are at wavelengths that allow them to more easily interact with oxygen in the atmosphere. The interactions lead to molecules being split, rather than the energy being absorbed (Incorrect Response A). Response C is incorrect because UVC (200 to 280 nm) has the shortest wavelength and highest amount of energy. Response D is incorrect because U V A (315 to 400 nm) is the lowest energy with the longest wavelength. It is also the most common form of U V radiation emitted by the Sun.
53	Answer to question 53	D	Objective 007 Infrared radiation is energy on the electromagnetic spectrum with longer wavelengths and lower energy than visible light. It does not have enough energy to break the bonds between atoms (Incorrect Response A) or to ionize an atom (Incorrect Response B), but it does have enough energy to cause the atoms in the water molecule to vibrate (Correct Response D). Incorrect Response C would not account for all of water vapor's effects because over 90% of the water in the atmosphere is not in a solid state.
54	Answer to question 54	B	Objective 007 Response B is correct because conduction occurs when heat is transferred between two objects with different amounts of heat energy through direct contact. The conditions in Incorrect Response A could result in heat conduction, but there would be more opportunities for conduction to occur if the surface and air were turbulent. The conditions in Incorrect Response C would not result in conduction because the ocean's surface and the air are the same temperatures and are already at an equilibrium. The two substances do not need to have the same composition, which means that Incorrect Response D can be ruled out.
55	Answer to question 55	D	Objective 007 Response D is correct because, as the light from the Sun hits the atmosphere and the surface of the Earth, the energy causes the lower atmosphere and the surface to warm. Due to the Earth's rotation and tilt, the surface is not heated evenly, creating areas of warmer air and areas of cooler air. While the newly warmed air is less dense and rises, cooler air moves in to take its place, creating surface winds. Water vapor concentrations (Incorrect Response A) can cause density differences, but this is not the primary way wind is generated. The speed of rotation (Incorrect Response B) does have a major impact on the direction and deflection of wind, known as the Coriolis Effect, but it does not create the wind. Pressure differences from the surface to the upper troposphere (Incorrect Response C) are also due to the uneven heating of the Earth. However, these differences are not the cause of wind but are a part of the same process of atmospheric convection.
56	Answer to question 56	B	Objective 007 Response B is correct because positive feedback occurs when changes to a system create conditions that amplify the original change. Within the earth's climate system, the melting of glacial ice decreases the albedo of the surface, causing the further melting of the ice. Weathering of continental rocks (Incorrect Response A) can be an example of a negative feedback loop. Weathering of rocks pulls carbon dioxide out of the atmosphere, which can create conditions where less weathering occurs. Neither carbon dioxide dissolving in the oceans (Incorrect Response C) nor water condensation (Incorrect Response D) create conditions to amplify their processes.
57	Answer to question 57	A	Objective 007 Response A is correct because the key to understanding many atmospheric processes is understanding the relationship between temperature and pressure and how changes to either affect the behavior of the gases in the atmosphere. This is the core of kinetic molecular theory (KMT). The ways in which heat transfers between objects (Incorrect Response B) and the laws of thermodynamics (Incorrect Response C) are important concepts, but ultimately they are building on KMT. The greenhouse effect (Incorrect Response D) also builds on KMT to explain why certain gases are better than others at changing the energy balance of our planet.
58	Answer to question 58	A	Objective 007 Response A is correct because deforestation significantly reduces the sequestration of carbon dioxide, a potent greenhouse gas. With less forest to sequester carbon dioxide, the concentration of carbon dioxide in the atmosphere increases, warming the atmosphere. A warmer atmosphere warms the oceans, causing the volume of water to increase. This, together with the melting of land-based glaciers from a warmer atmosphere, raises sea level. Algal blooms triggered by coastal runoff (Incorrect Response B) increase carbon sequestration and so would have little effect on sea-level rise. Similarly, volcanic eruptions in the tropics (Incorrect Response C) typically cool the atmosphere and consequently cool the oceans, reducing glacial melt and decreasing the rate of sea-level rise. An increase in wind-blown dust from desertification (Incorrect Response D) typically reduces the temperature of the troposphere, which would also not lead to a rise in sea level.
59	Answer to question 59	B	Objective 007 Response B is correct because when atmospheric carbon dioxide dissolves in seawater, it reacts with the water to produce carbonate and bicarbonate ions. The bicarbonate ions combine with calcium ions when marine invertebrates, such as corals, make their protective shells. This is an important step in the cycling of carbon between the atmosphere and lithosphere because the reef carbonates formed by corals eventually become the extensive limestone deposits of the lithosphere. Carbonic acid produced during the weathering of limestone moves into the hydrosphere, not the lithosphere (Incorrect Response A). The decay of biomass (Incorrect Response C) moves carbon from the biosphere to the atmosphere. Atomic carbon is highly reactive and so by itself is not directly absorbed by deep-ocean sediments (Incorrect Response D).
60	Answer to question 60	A	Objective 007 Response A is correct because when sunlight strikes Earth's atmosphere, it is scattered by atmospheric molecules. This phenomenon is called Rayleigh scattering and affects shorter blue-violet light more than longer, redder waves. Molecules in the air are polarized by light waves before radiating energy as visible light to return to their previous, mostly unpolarized states. The observed effect of this radiation is the scattering of light. Higher energy, blue-violet visible light is more prone to this absorption and scattered re-radiation than lower energy, redder waves. Although some long wavelengths in sunlight are reflected, reflection of longer wavelengths (Incorrect Response B) is not responsible for the sky's color. Sunlight is refracted as it passes through water droplets, but it is not refracted by gaseous water vapor (Incorrect Response C) and therefore does not affect the sky's color. While water vapor accounts for up to 70% of the absorption of incoming sunlight, its selective absorption of different wavelengths does not cause the sky to appear blue (Incorrect Response D).
61	Answer to question 61	B	Objective 007 Response B is correct because cloud cover at night reduces the amount of heat that radiates into space by absorbing the heat radiating from the surface and reradiating some of it back down toward the ground. The process slows the rate of surface cooling and traps heat near Earth's surface, keeping temperatures warmer than they would be otherwise. Evaporation rates (Incorrect Response A), and hence evaporative cooling, are usually lower at night in general, but this does not account for the warming effect of nighttime cloud cover. Atmospheric convection currents are not significant at night because solar heating is not available to warm the air near the surface and cause it to rise (Incorrect Response C). Cloud cover at night tends to reduce condensation, consequently reducing the release of heat energy from condensation (Incorrect Response D).
62	Answer to question 62	D	Objective 007 Response D is correct because the Coriolis effect is an apparent deflection of objects moving in a straight line on a rotating frame of reference. The Coriolis effect is an important factor affecting the movement of water and air as they travel across Earth's curved and rotating surface. It affects the flow of air around atmospheric pressure systems and in prevailing wind currents, as well as the flow of ocean currents. The cooling of rising air (Incorrect Response A) results from the decrease in pressure with increasing elevation and the conduction of heat energy into the surrounding cooler air and has nothing to do with the Coriolis effect. Air currents rarely travel in a straight path for very long (Incorrect Response B) no matter where they are because of the Coriolis effect and other geographic factors. Air heats up as it sinks because of compressional heating as the pressure in the sinking gas increases (Incorrect Response C), which is unrelated to the Coriolis effect.
63	Answer to question 63	C	Objective 008 Response C is correct because climate is the result of long-term averages in temperature and precipitation for a given area and it is the only response that gives an example of a short-term or weather event. In short, climate is what can be expected from an area over a length of time. Incorrect Responses A and B are both referring to climate because they are referring to long-term data rather than short-term events. Incorrect Response D focuses on the expected temperature pattern, which means it is also referring to climate.
64	Answer to question 64	C	Objective 008 Response C is correct because changes in the climate of an area are changes to the long-term averages in temperature and precipitation. One data point, such as one day, one week, or even one year's temperature or precipitation, does not allow climate scientists to infer changes to the long-term averages. However, the short-term data are relatively easy to collect (Incorrect Response A). Gathering short-term weather data aids in building a record of long-term trends in the temperature and precipitation of a region. Telling a student that the topic is too difficult to understand does not help them build a deeper understanding of the topic (Incorrect Response B). While the climate is warming, its effects are not uniform. Telling the student that the effect will be minimal in their area would discourage observation and critical thinking around the topic (Incorrect Response D).
65	Answer to question 65	D	Objective 008 Typically, atmospheric temperatures decrease with increasing elevation. When colder air lies below warmer air, this pattern is reversed and is known as a temperature inversion. Inversions often occur under still conditions or when there is a topographic feature that blocks the movement of air masses (Correct Response D). For instance, temperatures in downtown Fairbanks, Alaska, are often much colder than the surrounding hills. The cold air is denser and sinks down into the valley while the warmer, less dense air sits above it. Inversions typically do not form through contact with the ground (Incorrect Responses A and B), nor by two cold air masses colliding (Incorrect Response C).
66	Answer to question 66	A	Objective 008 Response A is correct because this scenario describes the formation of an occluded front. Depending on the exact nature of the air masses, there can be a variety of conditions present. The most likely result of occluded front formation is the drying of the air mass resulting in a scattering of puffy cumulus clouds (not sunny skies, as in Incorrect Response B) and low humidity (not high humidity, as in Incorrect Response D). While cold fronts are associated with heavy precipitation, occluded fronts generally do not produce strong winds or tornadoes (Incorrect Response C).
67	Answer to question 67	D	Objective 008 Response D is correct because tropical regions experience the most stable climate. The amount of solar energy varies little over the course of the year, leading to those areas experiencing minimal temperature changes. Tropical regions are clustered near the equator and areas of relatively permanent low pressure, meaning that they will experience frequent rainfall throughout the year. Climate zones that tend to occur further from the equator—like Incorrect Responses A, B, and C—will have greater seasonal changes.
68	Answer to question 68	D	Objective 008 Response D is correct because climatic regions are defined by their annual patterns in temperature and precipitation. For instance, both arid regions and temperate regions can experience dry summers, and warm summers can be experienced by those in both the cold/continental and the temperate regions. Comparing regions over a short period of time (Incorrect Response A) may allow for accurate categorization, but short-term variations like a regional drought or a year with particularly high rainfall may mask the broader patterns for that climatic region. If given only one dimension, as in Incorrect Responses B and C, there is not enough information to completely distinguish between regions.
69	Answer to question 69	A	Objective 008 Response A is correct because the scientist collecting the data can plot a line of best fit for the data set and then extend the line of best fit to predict likely future trends. It is impossible to know the average temperature for each coming year (Incorrect Response B), so adding it to the median of the data set is not possible. The range of the data set (Incorrect Response C) is the difference between the highest and lowest values and does not provide information useful for predicting future trends if the temperature is increasing over time. Calculating the total change over time in the data set to predict the minimum future increase in temperature (Incorrect Response D) is vague and does not specify over what time period that minimum increase can be expected, so it is not the best tool for predicting future trends.
70	Answer to question 70	D	Objective 008 Response D is correct because the larger cross-sectional area of a rain gauge's collector as compared with its measuring tube is designed to provide more precise measurements, especially of light rain. Since the cross-sectional area of the top of the collector is 10 times greater than the cross-sectional area of the measuring tube, the amount of rain deposited in the measuring tube is divided by ten to provide a measurement of rainfall. The design does not necessarily provide a more realistic measure of the average rainfall (Incorrect Response A), and it will not reduce the effect of wind (Incorrect Response B) or minimize the amount of splashed rainwater that can enter the device (Incorrect Response C). Both wind and splash are typically controlled by appropriate placement of the device.
71	Answer to question 71	B	Objective 008 Response B is correct because a developing low-pressure system typically has a warm front marking the leading boundary of relatively warm moist air and a cold front that marks the leading edge of colder air wrapping around the developing low-pressure system. This is the process of cyclogenesis that leads to storm formation. When the faster-moving cold front catches up with the warm front, it forces the less-dense warm air upward, triggering precipitation along the now occluded front. Occluded fronts do not develop when one warm front catches up with another (Incorrect Responses A and C) or when a cold front catches up with another cold front (Incorrect Response D). In each of these responses, the similar fronts would typically reinforce each other and not form a new kind of front.
72	Answer to question 72	B	Objective 008 Response B is correct because annual average precipitation in the prairie of the upper Midwest is sufficient to support a grassland ecosystem and isolated trees in some favored locations. The fairly low average annual precipitation and its often-erratic nature can create extremely hot and dry summer conditions that give grasses a competitive advantage over tree species. For this reason, precipitation is the primary climate characteristic that controls the types of vegetation that can successfully compete in the prairie. The strong winds that often blow across the region (Incorrect Response A) increase evaporation in summer, further reducing available soil moisture, but it is the relatively low precipitation that makes this a problem. The grass fires in the region (Incorrect Response C) result from the very dry summer conditions caused by low and erratic rainfall as well. The wide variation in temperature over the course of the year (Incorrect Response D) does not prevent trees from growing in the area.
73	Answer to question 73	C	Objective 008 Response C is correct because the prevailing large-scale winds over the United States blow from west to east. This is the most significant factor affecting the different seasonal temperature patterns along the East and West Coasts. The prevailing winds tend to blow relatively warm marine air from the Pacific Ocean to the West Coast, moderating both winter and summer temperatures, while prevailing winds in the central and eastern United States tend to bring cold continental air masses to the East Coast in the colder months and hot continental air masses in the warmer months. Neither the inland topography of the two coasts (Incorrect Response A) or their different seasonal precipitation patterns (Incorrect Response B) are primarily responsible for the difference in their seasonal temperature patterns. Although near-shore waters on both coasts play an important part in moderating local temperatures along the coastlines (Incorrect Response D), the phenomenon is not responsible for the larger-scale yearly temperature patterns depicted in the graph.
74	Answer to question 74	D	Objective 008 Response D is correct because the geographic area of the United States was located near the equator and subtropics during the Paleozoic era. The shift in tectonic plates that formed Gondwanaland in the Early Paleozoic and Pangaea in the Late Paleozoic is responsible for the tropical climate conditions in the region at that time. The concentration of oxygen in the atmosphere (Incorrect Response A) and the intensity of solar radiation (Incorrect Response B) during the Paleozoic era were not primarily responsible for the region's tropical climate. Ocean currents during the 300 million years of the Paleozoic era (Incorrect Response C) likely changed dramatically over that time period and certainly must have affected climate. However, it was primarily the geographic location that was responsible for changes in ocean currents and the region's tropical climate.
75	Answer to question 75	D	Objective 008 Response D is correct because, in meteorology, advection is the bulk movement of energy or mass horizontally through the atmosphere, and advection fog is fog that forms when relatively warm moist air flows over a colder surface such as the ocean. When cold air becomes trapped beneath warm air (Incorrect Response A), an inversion results and not advection fog. Hot, relatively dry air (Incorrect Response B) can produce fog if it is cooled below its dew point. This type of fog is called radiation fog because it forms in place as the ground radiates its heat and cools down. When cool, moist air flows down a mountain (Incorrect Response C), the pressure on the parcel of air increases, reducing its volume and increasing its temperature. This type of adiabatic warming causes the relative humidity of the parcel to decrease and would not produce fog.
76	Answer to question 76	B	Objective 009 Response B is correct because, no matter if a natural gas pipeline is laid above or below ground, there is going to be significant disruption to the ecosystem during its construction. There are potential ramifications if a natural gas pipeline breaks, such as a wildfire (Incorrect Response A), but it is not the most likely scenario. Groundwater contamination (Incorrect Response C) is more likely to be an issue with the transportation of oil. While natural gas is primarily methane ( C H 4 ), the main pollutant causing surface water acidification is carbon dioxide ( C O 2 ) (Incorrect Response D).
77	Answer to question 77	C	Objective 009 Unmodified rivers transport both water and sediment as they flow towards their mouths. When a river is dammed, the water continues to flow, but the sediment becomes trapped behind the dam. As a reservoir fills with sediment, it decreases the volume of water that it can hold (Correct Response C). Reductions in precipitation (Incorrect Response A) are typically not due to the presence of the reservoir. With larger dams, the degradation of the watershed (Incorrect Response B) is much more likely to be due to changes to downstream areas rather than the upstream flow. Evaporation rates (Incorrect Response D) are helpful to consider when siting a hydroelectric dam, but the flow rate of the rivers feeding the reservoir will have a greater impact on the dam's ability to function.
78	Answer to question 78	D	Objective 009 Response D is correct because the consequences of exposure and the ensuing health care costs and effects on health and well-being are hidden from the consumer. They are not priced into the cost of electricity and fall on individuals, families, and communities without any financial compensation. The price electric companies charge to consumers for fossil fuel–powered electricity builds in the costs of maintenance (Incorrect Response A) and transportation (Incorrect Response B). Consumers are typically taxpayers, and a portion of their tax dollars goes to fund federal and state subsidies to energy companies (Incorrect Response C), so this is not a hidden cost.
79	Answer to question 79	D	Objective 009 Response D is correct because, through opening up the canopy while preserving neighboring mature trees, favorable conditions are created for the growth of shade-intolerant species including early successional plants. This increases the biodiversity of the site. Removing trees can help slow the spread of insect pests but harvesting in a checkerboard fashion still leaves plenty of hosts for the pests and generally will not slow their spread or effect (Incorrect Response A). Depending on the method of removal, additional shelter can be created, but not likely for the same organisms that were living in the mature forest (Incorrect Response B). Both the upper, leafy portion of a tree as well as its root system can help improve soil infiltration, but trees tend to have high transpiration rates (Incorrect Response C).
80	Answer to question 80	A	Objective 009 Response A is correct because drip irrigation allows for farmers to give plants just the amount of water they need where they need it. Waiting until crops are experiencing water stress and slowed growth (Incorrect Response B) has the potential to impact yields. Using a sprinkler method for irrigation is a less efficient method for watering crops than drip irrigation and will result in water waste even if the crops are well-adapted to arid conditions (Incorrect Response C). Further, replacing crops may not always be a viable option. For example, California's Central Valley has an arid climate. One of the main agricultural centers of the Valley, Fresno, receives around 4 inches of rain annually, which is not enough to support most crops without irrigation (Incorrect Response D).
81	Answer to question 81	B	Objective 009 All of the responses can be indicators of water quality, but water pH and the amount of dissolved oxygen are the most universal of the measurements. Response B is correct because most organisms can only live within a relatively narrow pH range and require a certain amount of dissolved oxygen to survive. Water temperature (Incorrect Response A) as a measure of water quality is relative to the ecosystem and environment. Some organisms need cold water to survive, while others need warmer waters. There are a wide variety of pollutants that can exist in the water column (Incorrect Response C), but only some of them will be visible unaided. Many water pollutants are harmful in concentrations as low as just a few parts per billion. The types of organisms present (Incorrect Response D) can potentially be indicators of water quality, particularly if pollution-sensitive organisms are regularly found in a body of water. However, the surveys needed to check for those organisms may not be appropriate for all types of surface water and are much more resource intensive than a probe that can measure water chemistry.
82	Answer to question 82	C	Objective 009 Response C is correct because the mean, or the arithmetic average, gives the scientist the best metric for comparison. The mode (Incorrect Response A) gives the most frequent value but does not describe the trend of the month. The median (Incorrect Response B) and range (Incorrect Response D) provide information on the variation and the central tendency, but they do not weight the data in a way that makes comparison particularly valid.
83	Answer to question 83	C	Objective 009 Hydrothermal alteration of minerals in the country rock surrounding a pluton occurs as hot mineral-rich fluids move from a cooling pluton into the surrounding country rock. The process alters the chemistry and makeup of the surrounding rock and can deposit precious metals within fractures as the fluids cool. By adding, removing, and redistributing chemical elements in the surrounding country rock, hydrothermal fluids alter the minerals in the rock and can concentrate precious metals, such as gold and silver (Correct Response C). Isostatic readjustments (Incorrect Response A) that cause vertical changes in the crust do not directly affect local geochemical processes involved in the formation of economically valuable minerals. Magmatic differentiation (Incorrect Response B) changes the magma's composition as minerals crystallize during cooling, but it does not directly form concentrations of precious metals. Chemical weathering (Incorrect Response D) does not occur extensively within country rock and therefore does not play a role in concentrating precious metals found there.
84	Answer to question 84	C	Objective 009 Response C is correct because phytoplankton are microscopic marine plants that fix atmospheric carbon dioxide as they use sunlight to make organic molecules during photosynthesis. Coral polyps are marine animals in the phylum Cnidaria and do not fix atmospheric carbon dioxide (Incorrect Response A). While one phylum of bacteria (Incorrect Response B) (i.e., cyanobacteria or blue-green algae) do photosynthesize and fix carbon dioxide, the vast majority of bacteria do not. Protozoa (Incorrect Response D) digest the food they take in from their environment in vacuoles and do not fix atmospheric carbon dioxide. Although protozoa constitute a complex and diverse group of microscopic eukaryotes, they were traditionally considered to be animal-like to distinguish them from photosynthesizing phytoplankton and because of their motility and predatory behavior.
85	Answer to question 85	B	Objective 010 Response B is correct because pyroclastic flows are extremely hot (200 to 700 degrees Celsius ) mixtures of rock, gas, and ash traveling 80 km/hour or faster. Although there is ash in pyroclastic flows (Incorrect Response A), it is escapable and therefore not as dangerous as the flow itself. Shield volcanoes have low-viscosity mafic lava that flows easily but slowly. Often flowing no faster than 10 kilometers per hour, these flows are relatively easy to escape on foot. Pyroclastic flows are generally much more dangerous than lava flows from shield volcanoes, despite the lava from the shield volcano being hotter at over 1,100 degrees Celsius (Incorrect Response C). Although there can be inclusions of pieces of rock within pyroclastic flows (Incorrect Response D), the major source of damage is the heat and speed.
86	Answer to question 86	A	Objective 010 Response A is correct because, if regions are significantly wetter or drier than in the past, then the crops that are typically grown there may struggle. Some areas may even become too dry to support agriculture, which would reduce the amount of arable land around the world. Climate change is affecting the severity of storms (Incorrect Response B) and the rise in sea levels (Incorrect Response D), but these two factors will not have as great of an impact on the global food supply as changing precipitation patterns. As climate changes, there will be more opportunities for adaptable species to become invasive (Incorrect Response C), but they are unlikely to have as large of an impact as a shift in precipitation patterns.
87	Answer to question 87	D	Objective 010 Response D is correct because the largest impact from major eruptions is the temperature fluctuations caused by the aerosols that travel up beyond the troposphere into the stratosphere. Once the gases are in the stratosphere, they cannot directly impact human health (Incorrect Response B). 18 16 is known as the year without a summer due to the massive eruption of Mount Tambora in Indonesia. The amount of sulfur dioxide blocked much of the Sun's energy causing at least a 0.4 degrees Celsius drop in global temperatures. This drop caused crops to fail in Europe and across North America. The sulfur dioxide eventually precipitated out of the atmosphere as acid rain (Incorrect Response C) but did not cause as large of disruptions to the environment as the sulfur dioxide. While massive eruptions can cause a large amount of carbon dioxide to be released, it is typically not enough to cause large fluctuations in temperature (Incorrect Response A). For instance, the 20 22 eruption of Tonga's volcano caused the atmospheric carbon dioxide concentration to rise from 412 parts per million (ppm) to 414 ppm. This is the equivalent of an entire year's worth of carbon dioxide emissions. Still, the cooling effect of the sulfur dioxide in the eruptions generally cancels out the warming effect of the carbon dioxide.
88	Answer to question 88	B	Objective 010 A tiltmeter is a specialized form of an inclinometer, or a device that measures the angle of a slope. When placed on a volcano, the tiltmeter will register changes in the slope, which are typically due to magma filling chambers below the surface and causing surface distortions (Correct Response B). Other indicators of a likely eruption can be measured using other devices or methods. By looking at the composition of the volcano and knowing its history, vulcanologists can predict the viscosity of the magma and therefore the explosivity of an eruption (Incorrect Response A). Understanding the current topography and location of magma chambers can indicate where the lava will likely flow (Incorrect Response C). Measuring frequency and amplitude of minor earthquakes (Incorrect Response D) with a seismometer can indicate how likely an eruption is in the near future. This is not a reliable indicator since volcanoes can experience an earthquake swarm independent of an eruption.
89	Answer to question 89	C	Objective 010 Doppler radar allows scientists to observe the wind speeds within a storm, and GPS systems provide the storm's location information. Tracking where a storm has been and how fast the winds are moving helps make predictions about where a storm is headed in the future (Correct Response C). While GPS and Doppler can predict the likelihood that there are conditions present to form a tornado, it is impossible to predict with these models the likelihood that one will touch the Earth's surface (Incorrect Response A). The maximum wind speeds (Incorrect Response B) give information on how severe the storm is likely to be. Although a storm system may be tracked by GPS and Doppler radar, there are better tools for tracking current behavior of the storm system in terms of development time (Incorrect Response D).
90	Answer to question 90	A	Objective 010 Response A is correct because rapid climate changes, both now and in Earth's prehuman history, have often been due to shifts in the balance of the carbon cycle, and there is evidence of large-scale volcanic eruptions that caused significant, rapid global warming. Processes that took carbon out of the active cycling process, like uplift leading to increased weathering (Incorrect Response B) and plant burial (Incorrect Response D), often caused the planet to experience cooling because carbon is pulled out of the atmosphere and biosphere, respectively. Processes that added carbon to the shorter-term cycling of carbon tended to cause the planet to experience warming. There is little evidence that methane releases have triggered past warming events (Incorrect Response C) because the methane dissolves in water easily and, therefore, is not around to warm the surface.
91	Answer to question 91	C	Objective 010 The energy that is propagated outward from the focus of the earthquake comes in two forms: body waves and surface waves. Surface waves cause the earth to move along the ground horizontally and tend to be the larger cause of damage. Buildings in the area will be subjected to sustained back and forth motion which, because of the structure's inertia, causes tremendous shear forces (Correct Response C). Although earthquakes cause compressive stress, since structures are already constructed with compressive stresses in mind, particularly those due to gravity and the mass of the building, it is not the primary type of stress that causes damage during earthquakes (Incorrect Response A). Earthquakes tend not to cause torsional (twisting) (Incorrect Response B) or tensional (pulling) (Incorrect Response D) stresses.
92	Answer to question 92	B	Objective 010 Response B is correct because, to investigate the causes of an extended drought, the climatologist first needs to establish the variables that have affected the region's precipitation during the drought. The management of drought conditions (Incorrect Response A) is a practical concern unrelated to the drought's causes. The duration of previous droughts (Incorrect Response C), while useful information, does not get at the underlying causes of the current extended drought. Similarly, Incorrect Response D is an interesting question but not the strongest foundation for investigating the causes of the current drought.
93	Answer to question 93	B	Objective 010 Response B is correct because the shape of Hawaiian shield volcanoes results from the mafic composition of the magma that generates low-viscosity magma flows during eruptions. This lava's viscosity is low, so the lava generated is very fluid and flows easily over long distances before solidifying. The gas content (Incorrect Response A) of magmas feeding Hawaiian-style eruptions is low and, although it does affect viscosity, is not as important as the magma's silica content. Hawaiian lavas are mafic, and their relatively high iron content (Incorrect Response C) is not a major factor in the lava's low viscosity. Lava with a felsic composition (Incorrect Response D) is more viscous than mafic lava and is associated with more explosive stratovolcanoes and not Hawaiian-style shield volcanoes.
94	Answer to question 94	B	Objective 011 Increasing the acidity of the ocean negatively impacts the availability of dissolved calcium carbonate. As the pH increases, organisms such as the tiny pteropod must spend more of their energy to build and maintain their shells and skeletons (Correct Response B). An increase of nutrients can lead to increased growth, but that is typically due to water pollution, not ocean acidification (Incorrect Response A). Ocean acidification, while increasing the amount of dissolved carbon dioxide, would not greatly impact the oxygen concentration (Incorrect Response C). However, increasing ocean temperatures will lead to less dissolved oxygen, making it harder for fish to breathe. Increased carbon dioxide (Incorrect Response D) can help improve primary productivity to a point but will quickly be limited by other factors, such as the availability of light and nutrients.
95	Answer to question 95	C	Objective 011 Climate change is causing the higher latitudes to increase in temperature faster than other parts of the world. Methane is a much more potent greenhouse gas than carbon dioxide, and its release from the permafrost will likely have a significant impact on climate change (Correct Response C). Incorrect Response A is a way that carbon dioxide can be removed from the atmosphere. Incorrect Responses B and D are both likely to have impacts on increasing the amount of greenhouse gases in the atmosphere but do not represent as much volume as the methane referenced in Correct Response C.
96	Answer to question 96	D	Objective 011 Response D is correct because the scientist's conclusion would be undermined if the uncontaminated test wells were found to be drawing water from a different aquifer than the contaminated confined aquifer that supplies the drinking-water well. The test wells that are up-gradient from the drinking water well (Incorrect Response A) would flow down-gradient to the drinking water well, so that does not affect the validity of the scientist's conclusion. The fact that the pump at the contaminated test well was off when samples were collected (Incorrect Response B) does not undermine the scientist's conclusion, as contaminant levels would be higher, if anything, in a pumping well. There are strict protocols for collecting water samples that professional scientists are required to follow, and the samples are processed in a laboratory, so having more than one person collect the samples (Incorrect Response C) does not reduce the validity of the scientist's conclusion either.
97	Answer to question 97	B	Objective 011 Removing data because the data differ from expected results would most strongly bias the researcher's analysis (Correct Response B). Noting flaws in the research design that may have generated faulty data (Incorrect Response A) does not introduce bias into the researcher's analysis of the data, but it does suggest that there are possible problems with the data set. Changing the way that the data are presented graphically to improve readability (Incorrect Response C) and summarizing and averaging the data (Incorrect Response D) do not bias the analysis as long as graphics are clearly labeled and averaged values are clearly described as averages.
98	Answer to question 98	A	Objective 011 Climatologists generally do not directly attribute changes in the climate system, such as an increase in hurricane frequency, to global warming. This is because the climate system is a highly complex system that responds to change through numerous feedback loops that are still only partially understood (Correct Response A). The idea isn't entirely made-up (Incorrect Response B), as warmer oceans do increase the probability of hurricane formation, but ocean temperature is only one part of the complex sequence of events that leads to the development of a major hurricane. Most climatologists do not see climate change issues as only being a government concern (Incorrect Response C), and while they do not like it when the media use unethical strategies for selling news (Incorrect Response D), it is the accuracy of the reporting that primarily concerns the scientific community and not the potential disruption to the economy.
99	Answer to question 99	A	Objective 011 One of the strongest hypotheses of the climatologists studying climate change and the predictions of climate models is that weather events will become more extreme. This means longer and more severe droughts for some areas already prone to drought, such as the Southwestern United States, while other regions typically prone to seasonal flooding, such as the Ohio River Valley, can expect more intense floods more often (Correct Response A). Climate models suggest that the decreased equator-to-pole temperature gradient will actually make weather systems more persistent as the jet stream slows (Incorrect Response B), and hurricanes are more likely to increase in frequency than decrease as sea-surface temperatures increase (Incorrect Response C). El Niño events are precipitated by major changes in the oceans and atmosphere, and climate models have not indicated that the intervals at which they occur (Incorrect Response D) will change significantly as a result of global warming.
100	Answer to question 100	A	Objective 011 A major source of acid precipitation is the production of oxides of sulfur and nitrogen during fossil fuel combustion. These compounds combine with water in the atmosphere to form acid precipitation. Sulfur dioxide is the primary pollutant involved, and power plants use flue-gas desulfurization (FGD) technologies to remove sulfur dioxide from smokestack emissions. Reacting sulfur dioxide with calcium hydroxide in a lime-water spray is a wet-scrubbing technique that can remove 95% of the sulfur dioxide in emissions (Correct Response A). Since dust particles (Incorrect Response B) are not the cause of acid precipitation, removing them does not diminish the problem. Carbon monoxide (Incorrect Response C) is a pollutant produced by fossil-fuel combustion, but it is not a major cause of acid precipitation. While volatile hydrocarbons (Incorrect Response D) are produced during fossil-fuel combustion, they are not a primary cause of acid precipitation, and their removal prior to combustion is not feasible.
Total Correct:	Total Correct	Review your results against the test objectives.

Open Responses, Sample Responses, and Analyses

Question Number	Your Response Read about how your responses are scored and how to evaluate your practice responses
101	Answer to 101 Open Response Item Assignment #1 For each assignment, you may type your written response on the assigned topic in the box provided. Note: The actual test allows you to handwrite your responses on separate response sheets to be scanned for upload to the test. For this practice test, you may handwrite each response on 1–2 sheets of paper. Essay Response Field
First Sample Weak Response (show sample responsehide sample response)	First Sample Weak Response to Open-Response Item Assignment #1 Our sun is like millions of other stars in the universe. It is about 4.5 billion years old and should last another 5.5 billion years. The average lifespan for a low mass star is about 10 billion years. Eventually our sun will evolve into a white dwarf. The sun is one giant nuclear fusion reactor. In its core, we have hydrogen atoms undergoing fusion and forming hydrogen isotopes and the helium atoms. The result of this reaction is also large amounts of energy being released. By examining the spectral analysis of stars, we can determine what elements are in the stars, how hot they are, how old they are and in what direction they are traveling.
First Weak Response Analysis (show response analysishide response analysis)	Analysis of First Weak Response to Open-Response Item Assignment #1 This is an example of a weak response because it is characterized by the following: Purpose: This response does not address all elements of the prompt. The key scientific concepts related to the life cycle are not fully described, nor does the response address the need to include a representative graph, formula, or diagram with labels to model the reactions that occur in stars, resulting in the production of elements. The proposed use of the model of spectral analysis lacks explanation as to how the phenomenon is related to stellar evolution. Subject Matter Knowledge: The life cycle of the Sun and nuclear fusion are partially described, but the descriptions lack the details of the key scientific concepts related to the physical laws of the universe. A formula of the fusion reaction could have been included to model the formation of helium and its isotopes. Support: High quality, relevant examples are missing from the description of the process of a star's life span, such as the use of the H–R diagram, red giants, neutron stars, and black holes. The use of spectral analysis as described has little relevance to stellar evolution and is a limited example of "developing and using models" to increase student understanding. Rationale: The response demonstrates a poorly reasoned understanding of the topic with little connection between the life cycle of stars and their production of energy, particularly the radiation that reaches Earth.
Second Sample Weak Response (show sample responsehide sample response)	Second Sample Weak Response to Open-Response Item Assignment #1 Stars go through stages from creation to eventual extinction. Through the nuclear fusion taking place in a star's core, elements are combined, starting with the simplest being hydrogen, resulting in progressively heavier elements being formed which are in turn combined, and so on. One of the physical laws of the universe that drives this process is gravity. All matter has mass and mass reacts to gravitation. In the core of a star, which has a massive amount of gravity, these elements are forced together, hence their fusion. As the elements are changed their use as a "fuel" to power the reaction becomes less. The mass concentrated in the core of the star also increases. The creation of radioactive elements is responsible for the gamma and x-ray radiation that reaches the earth. All the wavelengths of the electromagnetic spectrum are emitted from stars. I would have the class look at a diagram of the spectrum and find where visible light is located and compare it to microwave and radio waves. This could be a form of using models to help them understand this phenomenon.
Second Weak Response Analysis (show response analysishide response analysis)	Analysis of Second Weak Response to Open-Response Item Assignment #1 This is an example of a weak response because it is characterized by the following: Purpose: This response partially addresses most elements of the prompt. The key scientific concepts are explained. There is no graph, formula, or diagram that models the reactions that occur in stars. The classroom investigation is vague and has very little detail. The response does not adequately address the life cycle of a star, lacking key terminology such as low and high mass stars. Subject Matter Knowledge: Scientific vocabulary is utilized throughout the response such as core elements, gravity, mass, and gamma and x-rays. However, statements are general and lack detail. For example, "In the core of a star, which has a massive amount of gravity, these elements are forced together, hence their fusion." There is no model demonstrating limited application of the subject matter. Support: High quality, relevant examples, such as the description of a star's lifespan and the creation of black holes, are largely missing from the response. Rationale: The response employs only a limited rationale utilizing a vague classroom activity that does not connect the key concepts to the phenomena of stellar evolution, demonstrating poorly reasoned understanding of the topic.
First Sample Strong Response (show sample responsehide sample response)	First Sample Strong Response to Open-Response Item Assignment #1 When stellar nebulae condense, they can form stars. Depending upon the mass of the nebulae we get different size stars. If there is a large number of nebulae, we can have different size stars forming. In a low mass star, over time, the star will evolve as follows: a main sequence star becomes red giant becomes planetary nebulae becomes white dwarf. In a high mass star, the evolution is: a main sequence star becomes super red giant becomes supernova becomes neutron star. If it is a very high mass star, the final stage will be a black hole. This process can take about 10 billion years for low mass stars. The mass of the star provides the "fuel" for fusion, which takes place in the core. The fusion process starts with the lightest of elements, hydrogen. The mass of the star determines both the star's lifespan and the elements that it will eventually form. The larger a star is, the higher the pressures and temperatures are in its core. Stars with higher mass can form heavier elements, but the elevated temperatures mean that they also burn through their fuel much faster than lower-mass stars. After stars die off, this process repeats itself and new stars are reborn. The chemical reaction that takes place in stars is nuclear fusion. In nuclear fusion, two nuclei with low mass numbers combine to produce a single nucleus with a higher mass number. See the scanned document for the formula. In low mass stars hydrogen atoms fuse together to form helium molecules and release high amounts of energy. In higher mass stars heavier elements such as iron can be formed. In all cases, high amounts of energy are released that eventually reach the earth in the form of radiation. In all cases, the general reaction will be the fusion of 2 H atoms to form different isotopes of hydrogen, Deuterium and Tritium. Then we will have further fusion into Helium and isotopes of Helium. In every reaction very high amounts of energy are given off. By using spectral analysis of the stars in the sky, we can determine what elements are being formed in different stars. By looking at the H-R diagrams of stars students can determine the relative number of elements in the stars, the mass of the stars, and their respective ages. Students can also predict the ages of stars and the directions in which they are moving.
First Strong Response Analysis (show response analysishide response analysis)	Analysis of First Strong Response to Open-Response Item Assignment #1 This is an example of a strong response because it is characterized by the following: Purpose: This strong response has fully achieved the purpose of the assignment. The key scientific concepts that govern the life cycle of stars are accurately and fully described, including the stages of star development. There is a representative formula of nuclear fusion. The response includes the engineering model of H–R diagrams to engage students and help them understand the phenomena. Subject Matter Knowledge: There is substantial and accurate subject matter knowledge including the cycles of low and high mass stars, the amount of time it takes for the cycles to complete, and the difference in time frame of low and high mass star cycles. The response includes the regenerative nature of the phenomenon: this process repeats itself and new stars are reborn. Support: The formula for nuclear fusion and the description of the process that forms the different isotopes of hydrogen, Deuterium and Tritium, strongly support the subject matter. The level of specificity provides strong support—for example, that the reaction also produces Helium and isotopes of Helium. Rationale: The response demonstrates a sound argument connecting subject matter knowledge with substantial support to address the topic. The classroom activity of spectral analysis is a strong model to help students understand stellar evolution, reflecting both strong reasoning and a comprehensive understanding of the role of nuclear fusion in the process.
Second Sample Strong Response (show sample responsehide sample response)	Second Sample Strong Response to Open-Response Item Assignment #1 When you look up at the sky you see the past. Some of the stars we see are no longer in existence while others are in their infancy. Stars go through a life cycle as do all living things, but as soon as stars die off, others are born from their debris. Depending upon how much debris comes together, you will get either a high mass or a low mass star. High mass stars will evolve into a super red giant then into a super nova to a neutron star and, if the mass is high enough, a black hole. Our sun is a low mass star, and it will eventually turn into a red giant then a planetary nebula and eventually into a white dwarf. This process will take about 10 billion years. Our sun is in midlife as it is about 4.5 billion years old. Stars die out when the fuel in the core of the sun is used up. Hydrogen atoms in the core stop undergoing fusion and turn into hydrogen isotopes and then helium atoms and other isotopes. If the star is of heavier mass, then iron and other heavy metals can be formed. While this fusion process is going on, tremendous amounts of energy are being released in the form of radiation. Below is an example of a simplified H-R diagram. By looking at H-R diagrams and spectral analyses of the stars, students will have the ability to determine what elements are being formed, where the star is in its life cycle, and which way it is moving. The distance from stars is measured in light–years, the distance light travels in a year. That is why we are sometimes looking at the past. A star that we see as a nova no longer exists. In this way we can look at the past and hopefully see how stars die and are then born again. An image of the Hertzsprung-Russell diagram. Temperature information is on the x-axis on a descending, logarithmic scale starting at 40,000 Kelvin to 2,500 Kelvin. The y-axis indicates a star’s luminosity, also on a logarithmic scale which starts at 0.001 times as bright as the sun near the origin to 10,000 times the brightness of the sun at the top. The diagram shows the diagonal curve from upper left to lower right representing the main sequence of stars. Super giants are located in the upper right with giants below that. White dwarfs are located to the left of the main sequence at luminosities that are less than our Sun.
Second Strong Response Analysis (show response analysishide response analysis)	Analysis of Second Strong Response to Open-Response Item Assignment #1 This is an example of a strong response because it is characterized by the following: Purpose: The response fully addresses all aspects of the prompt. The key scientific concepts are explained in detail. The graph is clearly labeled, showing the relationship between stars by luminosity and temperature. The response demonstrates comprehensive understanding through the combination of a clear explanation of the elements produced during the star's life cycle and the H–R graph model that engages students to make further investigations of the life cycle of stars. Subject Matter Knowledge: An in-depth knowledge of the subject matter is provided through the accurate and substantial description of the life cycle of stars, age of our sun, stellar distances, and age of light reaching the earth. Support: High quality, relevant examples of the types of stars, unique requirements for the formation of iron, black holes, and how fusion is responsible for the release of energy support the subject matter knowledge. The H–R diagram adds support for these processes. Rationale: The connections between nuclear fusion and the production of elements such as helium, the release of energy in the form of radiation, and the life cycle of stars are ably reasoned. The concept of spectral analysis as used in the aging of stars demonstrates a comprehensive understanding of the topic.
102	Answer to 102 Open-Response Item Assignment #2 For each assignment, you may type your written response on the assigned topic in the box provided. Note: The actual test allows you to handwrite your responses on separate response sheets to be scanned for upload to the test. For this practice test, you may handwrite each response on 1–2 sheets of paper. Essay Response Field
First Sample Weak Response (show sample responsehide sample response)	First Sample Weak Response to Open-Response Item Assignment #2 Roots of plants can cause erosion. To test this claim we can plant several plants in clear plastic see through tubs and watch them over months examining the roots of the plants. By placing plastic chips on either side of the planted seeds, when the roots of the plants start to pry apart the chips, you will be able to see the start of erosion. Roots in trees can pry apart rocks. As part of an investigation of this last fact, students can be encouraged to visit a local area that might have examples of trees growing in cracks in hard surfaces such as sidewalks, pavement, or rocks and documenting their discoveries with sketches or photographs.
First Weak Response Analysis (show response analysishide response analysis)	Analysis of First Weak Response to Open-Response Item Assignment #2 This is an example of a weak response because it is characterized by the following: Purpose: This response addresses all elements of the prompt but has very little detail. There is a testable scientific claim that roots of plants can cause erosion. The procedure lacks detail in that the required steps of sound scientific investigation, such as the identification of variables and constants, are missing. There is no indication of the data to be collected. The proposed activity addresses weathering rather than water runoff and soil erosion. Subject Matter Knowledge: There is a lack of scientific vocabulary such as independent variable, dependent variable, and control. The procedure lacks detail such as the type of plants, the amount of soil, and the kinds of chips utilized. Because there is no differentiation between erosion and weathering, there is inappropriate knowledge demonstrated. Support: There are no data collected to support or refute the claim that root plants cause erosion. The observation that the roots of the plants start to pry apart the chips is limited and neither supports nor refutes the claim. Rationale: The response employs only a limited rationale and lacks understanding of the topic. This response does not have sufficient detail and demonstrates a poor understanding of the interactions between Earth's hydrosphere and other Earth systems.
Second Sample Weak Response (show sample responsehide sample response)	Second Sample Weak Response to Open-Response Item Assignment #2 Erosion is caused by intense weathering by the atmosphere that causes soil, rocks, minerals, and other abiotic factors to be washed away, displaced, or moved to a different location. When an intense storm occurs, sand, plants and rocks can slide down a hill towards a bay. Surface water runoff can wash off many important minerals and organic matter from some regions, causing plants to wash away and the animals that consume them to be cut off from access to their food. In a scientific procedure, I would bring my students to Mount Washington in Massachusetts. We would scour the terrain to find a suitable, elevated, and inclined area to study past/previous erosions. The hypothesis would be that animals have lost access to their food plants due to erosion. The variables would be the steepness of the hill and the time it takes for organic material, minerals, and rocks to be displaced. This would be using data to help students understand the hydrosphere's influence on other Earth systems, specifically, in this case, trophic levels.
Second Weak Response Analysis (show response analysishide response analysis)	Analysis of Second Weak Response to Open-Response Item Assignment #2 This is an example of a weak response because it is characterized by the following: Purpose: This response addresses most parts of the prompt in a limited way. The testable scientific claim that animals have lost access to their food plants due to erosion is stated. The response is lacking in its description of the experimental procedure, relying instead on the description of erosion and the conditions on Mount Washington. Data are mentioned but not explained, nor is there a connection to the claim. Understanding is limited because there is no scientific investigation. Subject Matter Knowledge: Lack of a baseline makes it difficult to see what the investigation is producing for comparative data. Some scientific vocabulary is used such as variables and abiotic factors. However, the description of the variables—the steepness of the hill and the time it takes for organic material, minerals, and rocks to be displaced—is vague and lacks comparative support. Support: High quality, relevant examples are missing from the brief description of the procedure. Identification of a control and safety considerations are entirely absent. It is unclear how the procedure would help students understand trophic levels, as stated at the end of the description. Rationale: The response employs only a limited rationale. There is insufficient description of the scientific process to logically connect it to the expected outcome, demonstrating a poorly reasoned understanding of the topic.
First Sample Strong Response (show sample responsehide sample response)	First Sample Strong Response to Open-Response Item Assignment #2 A testable claim could be that if slope and rainfall rate are held constant, the rate of erosion will be in inverse proportion to the amount of vegetation on a slope. In other words, the greater the amount of vegetation, the lower the rate of erosion. It is the root structures that create a matrix in the deeper soil so that it is less able to wash away. For instance, after fires, such as in California, torrential rains cause dramatic erosion due to the greatly reduced number of viable trees, shrubs, flowers, and weeds. The rate of erosion is in direct proportion to the amount of rainfall and slope. The more rain, or the greater the slope, the greater the amount of erosion will be, therefore any experiment measuring the effects of vegetation on erosion would need to account for those relationships. An experiment could be created in a large-scale lab setting where the soil type and slopes were kept constant. The independent variable would be the number and type of vegetation in the soil. Overhead sprinklers could provide the same volume of simulated rain per minute for a specified amount of time. The amount of soil runoff, which is the dependent variable, could be determined by removing the liquid water from the soil-water mixture. One could also use optical instrumentation to measure turbidity and occlusion. The only safety considerations would have to do with proper handling of any glassware that would need to be used and exercising care in walking if water were spilled on the floor. Students could repeat the experiment three times, taking notes, then plot their results (data) on a graph and explain to the class how this supports the proposed claim, explaining the interaction of the hydrosphere and the biosphere. A control in this experiment, if one were felt to be needed, could be a bare slope of the same material subjected to the same amount of rainfall. If more vegetation (organized by type as well) led to less soil in the water, then this would indicate less soil erosion. Further studies could separately determine the nature of root structures as they interact with soil, as well as the effects of the above-ground features of the plants. A teacher could use the practice of "analyzing and interpreting data" by utilizing data, such as that from the Hubbard Brook Experimental Forest, to compare the effects of tree harvesting, together with rainfall rates and field station erosion records, to confirm or challenge the principles of this experiment.
First Strong Response Analysis (show response analysishide response analysis)	Analysis of First Strong Response to Open-Response Item Assignment #2 This is an example of a strong response because it is characterized by the following: Purpose: This is a strong response because it fully addresses all aspects of the prompt. A testable scientific claim—if slope and rainfall rate are held constant, the rate of erosion will be in inverse proportion to the amount of vegetation on a slope—is described and supported. A detailed scientific procedure is described in a large-scale lab setting with an opportunity to collect data that supports or refutes the claim. An alternate classroom activity, comparing the effects of tree harvesting with the amount of erosion, helps students understand the hydrosphere's influence. Subject Matter Knowledge: Thorough understanding of the components of a scientific investigation is evident in the candidate's attention to the use of controls, soil type, and amount of slope, as well as proper identification of the independent and dependent variables. The response also expresses the understanding needed to account for other variables affecting the outcome such as more vegetation or less soil. Scientific vocabulary is utilized throughout the response. Support: High quality, relevant examples of the set-up of the experiment, the expected outcomes, and the rate of erosion in direct proportion to the amount of rainfall and slope, support the subject matter knowledge. Rationale: The response demonstrates a sound understanding of how to pose a testable claim, construct an experiment to test it, and apply knowledge about soil erosion, rainfall, and slope.
Second Sample Strong Response (show sample responsehide sample response)	Second Sample Strong Response to Open-Response Item Assignment #2 The Amazon rainforest is a complex ecosystem that occupies a substantial area of the Earth's surface. The standard speaks of the interaction of the hydrosphere with other Earth systems and how changes in one can lead to changes in another. Cutting of rainforest trees leads not only to increased global temperatures, through loss of carbon storage, but also, paradoxically, to a decrease in rainfall in the forest itself. Moisture released by the plants increases the humidity of the atmosphere which, if sufficiently saturated, falls back as rain. Loss of this rainfall can lead to drying of the now-exposed rainforest soils. Dry soils are more prone to erosion through both winds blowing away precious fertile topsoil and rain carrying away topsoil with rainwater or by leeching nutrients through the soil. A classroom experimental claim could be that dry, dusty soils are more likely to erode than damp soils. Different trays of soil could be tilted at equal angles. Starting from near zero percent moisture, progressively varying degrees could be obtained by use of a plant mister, then measured with a soil moisture meter. A measured amount of water could be sprinkled equally over the trays and the resulting runoff could be collected from each. There is only a moderate concern for safety, mostly regarding how to safely dispose of broken glassware. The claim would be that the drier trays would show more soil loss, measured by the amount of soil settling in the bottom of graduated cylinders, filled to an equal level with the runoff collected from all trays. The relationship may not be completely linear since very saturated soils might show an increased amount of soil loss compared with only moderately dampened soils. The independent variable in this case is the amount of moisture in the soil. The dependent variable is the amount of soil settling in the cylinders. Other variables would need to remain constant across all the individual tests. A tray that matches the average percentage of moisture for undisturbed rainforest soils could serve as the control. Students will chart the results of all the specimen trays, analyze the results by means of a scatter plot and line of best fit across all trials, and share them with the class. Using the technique, "analyzing and interpreting data" can be employed if students see unexpected results such as those that refute the claim or produce a non-linear, or curved, relationship as mentioned above. They could be encouraged to interpret this result and suggest a reason for it, perhaps creating additional tests to confirm or refute their hypotheses.
Second Strong Response Analysis (show response analysishide response analysis)	Analysis of Second Strong Response to Open-Response Item Assignment #2 This is an example of a strong response because it is characterized by the following: Purpose: This strong response thoroughly addresses all requirements of the prompt. A testable scientific claim that dry, dusty soils are more likely to erode than damp soils addresses the relationship between the required elements. A specific and detailed procedure to investigate the claim is thoroughly described with safety features noted. The collection of data provides substantial evidence and an opportunity to interpret unexpected results. Subject Matter Knowledge: Thorough understanding of the components of a scientific investigation is evident in the candidate's attention to the use of a control, trays of soil tilted at the same angle. The independent variable (progressively varying degrees of moisture) and dependent variables (the amount of soil settling in the cylinders) are clearly indicated. The need to keep conditions constant between experimental groups is stated and a control (a tray that matches the average percentage of moisture for undisturbed rainforest soils) is provided. Scientific vocabulary is utilized throughout the response. Support: High quality, relevant examples of the conditions leading to changes in rainforest soils (decreased moisture and loss of dry soil due to wind and rain) are clearly expressed and support the subject matter knowledge. An area of safety concern is identified. Rationale: The response demonstrates a thorough understanding of the influence of the Earth's hydrosphere that causes changes to other systems. Substantial subject matter knowledge is connected to a well-described investigation with opportunities for the collection of data and for students to interpret and analyze results.
Review the Performance Characteristics and Score Scale for Written Performance Assignments.

Multiple Choice Question
Practice Test Evaluation Chart

In the evaluation chart that follows, the multiple-choice questions are arranged in numerical order and by test objective. Check your responses against the correct responses provided to determine how many questions within each objective you answered correctly.

Subarea 1 : Earth's Place in the Universe

Objective 0001: Analyze the structure of the universe.

Question Number	Your Response	Correct Response
1		D
2		D
3		B
4		A
5		C
6		C

Total Correct for Objective 1 out of 6

Objective 0002: Demonstrate knowledge of the solar system and the interactions of Earth, the Moon, and the Sun.

Question Number	Your Response	Correct Response
7		D
8		A
9		B
10		A
11		C
12		A

Total Correct for Objective 2 out of 6

Subarea 1 (Objectives 0001–0002) Total Total Correct for Subarea 1 out of 12

Subarea 2 : Earth's Systems: Geosphere

Objective 0003: Apply knowledge of the geologic history of Earth.

Question Number	Your Response	Correct Response
13		D
14		C
15		C
16		A
17		D
18		C
19		D

Total Correct for Objective 3 out of 7

Objective 0004: Analyze plate tectonics.

Question Number	Your Response	Correct Response
20		D
21		A
22		A
23		C
24		A
25		D
26		D
27		D
28		A

Total Correct for Objective 4 out of 9

Objective 0005: Apply knowledge of Earth materials.

Question Number	Your Response	Correct Response
29		D
30		C
31		C
32		D
33		B
34		D
35		B
36		C
37		A

Total Correct for Objective 5 out of 9

Subarea 2 (Objectives 0003–0005) Total Total Correct for Subarea 2 out of 25

Subarea 3 : Earth's Systems: Hydrosphere, Atmosphere, Weather, and Climate

Objective 0006: Demonstrate knowledge of the hydrologic cycle and water systems.

Question Number	Your Response	Correct Response
38		A
39		C
40		A
41		D
42		D
43		A
44		B
45		B
46		A
47		D
48		A
49		C
50		D

Total Correct for Objective 6 out of 13

Objective 0007: Analyze the atmosphere and atmospheric processes.

Question Number	Your Response	Correct Response
51		C
52		B
53		D
54		B
55		D
56		B
57		A
58		A
59		B
60		A
61		B
62		D

Total Correct for Objective 7 out of 12

Objective 0008: Demonstrate knowledge of weather and climate, including regional phenomena.

Question Number	Your Response	Correct Response
63		C
64		C
65		D
66		A
67		D
68		D
69		A
70		D
71		B
72		B
73		C
74		D
75		D

Total Correct for Objective 8 out of 13

Subarea 3 (Objectives 0006–0008) Total Total Correct for Subarea 3 out of 38

Subarea 4 : Earth and Human Activity

Objective 0009: Apply knowledge of geochemical cycles, natural resources, and sources of energy.

Question Number	Your Response	Correct Response
76		B
77		C
78		D
79		D
80		A
81		B
82		C
83		C
84		C

Total Correct for Objective 9 out of 9

Objective 0010: Analyze the types of natural and human-influenced hazards and their impacts on human populations.

Question Number	Your Response	Correct Response
85		B
86		A
87		D
88		B
89		C
90		A
91		C
92		B
93		B

Total Correct for Objective 10 out of 9

Objective 0011: Analyze the effects of human activities on Earth systems and strategies for mitigating their effects.

Question Number	Your Response	Correct Response
94		B
95		C
96		D
97		B
98		A
99		A
100		A

Total Correct for Objective 11 out of 7

Subarea 4 (Objectives 0009–0011) Total Total Correct for Subarea 4 out of 25

Practice Test Score Calculation

The practice test score calculation is provided so that you may better gauge your performance and degree of readiness to take an MTEL test at an operational administration. Although the results of this practice test may be used as one indicator of potential strengths and weaknesses in your knowledge of the content on the official test, it is not possible to predict precisely how you might score on an official MTEL test.

The Sample Responses and Analyses for the open-response items may help you determine whether your responses are more similar to the strong or weak samples. The Scoring Rubric can also assist in estimating a score for your open responses. You may also wish to ask a mentor or teacher to help evaluate your responses to the open-response questions prior to calculating your total estimated score.

How to Calculate Your Practice Test Score

Review the directions in the sample below and then use the blank practice test score calculation worksheet to calculate your estimated score.

Multiple-Choice Section

Enter the total number of multiple-choice questions you answered correctly:

Use Table 1 below to convert that number to the score and write your score in Box A:

189

Open-Response Section

Enter the number of points (1 to 4) for your first open-response question:

Enter the number of points (1 to 4) for your second open-response question:

Add those two numbers (Number of open-response question points):

Use Table 2 below to convert that number to the score and write your score in Box B:

Total Practice Test Score (Estimated MTEL Score)

Add the numbers in Boxes A and B for an estimate of your MTEL score:

A + B =

241

Practice Test Score Calculation Worksheet: Earth & Space Science (74)

Table 1:

Number of Multiple-Choice Questions Correct	Estimated MTEL Score
0 to 25	117
26 to 30	125
31 to 35	133
36 to 40	141
41 to 45	149
46 to 50	157
51 to 55	165
56 to 60	173
61 to 65	181
66 to 70	189
71 to 75	197
76 to 80	205
81 to 85	213
86 to 90	221
91 to 95	229
96 to 100	237

Table 2:

Number of Open-Response Question Points	Estimated MTEL Score
2	36
3	40
4	44
5	48
6	52
7	56
8	60

Use the form below to calculate your estimated practice test score.

Multiple-Choice Section

Enter the total number of multiple-choice questions you answered correctly:

total correct

Use Table 1 above to convert that number to the score and write your score in Box A:

estimated multiple-choice score