Grade 8 Objective 5

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Grade 8Objective 5
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1 The diagram above models
decomposition. In nature dead material is
broken down by decomposers, enriching the soil. A
gardener can speed up this decomposition
process by creating a compost pile. As the
material in the compost pile decomposes A
the amount of gases decreases B the
materials are kept dry C heat is
produced D compounds produce light
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2 Heavy rains in an aquifers recharge zone
cause rivers and streams to flood. How will
this most likely affect the aquifer? A The
total water volume will increase. B The
outflow from natural springs will decrease. C
The water level in the aquifer will
decrease. D The rate of water use by humans
will increase.
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3 The diagram shows the orbit of
the moon around Earth. Between which two points
will the moon appear to change from a new moon
to a quarter moon? A Q and R B R and
S C S and T D T and Q
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4 Evidence suggests that dinosaurs became
extinct when a large meteorite struck in the
area of the Yucatán Peninsula. Scientists hypoth
esize that this enormous impact killed all the
dinosaurs, even those on the other side of
Earth, because the F debris thrown into the
atmosphere blocked sunlight G heat flash from
the impact immediately vaporized all
life-forms H impact blasted the atmosphere
surrounding Earth into space J intense heat
completely boiled away the oceans
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5 In spring 2003 a natural rock
outcropping in New Hampshire called the Old
Man of the Mountain collapsed. Which of the
following most likely loosened the rock and
caused it to fall? F Heat turning sedimentary
rock into metamorphic rock G Water freezing
and thawing inside cracks in the rock H
Volcanic activity producing pressure at the
rocks base J Oxygen reacting with iron on the
surface of the rock
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6 In the picture above, the
rocks at the bases of the trees were separated
from the cliff face by water freezing and
thawing. Which process best describes the
breaking of the rock? F Soil erosion G
Mountain building H Chemical weathering J
Physical weathering
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7 Which of the following most promotes
chemical weathering in limestone? A
Freezing water B Blowing wind C Running
water D Growing roots
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8 The United States consumed about 19 million
barrels of petroleum per day in 2000. This rate
continues to increase. It is important
to develop alternative sources of energy
because petroleum F will eventually use up
all the oxygen needed for human survival G is
being spilled into the ocean faster than it is
being used H fails to store solar energy and
contains limited chemical energy J is a
limited source of energy that is almost
impossible to renew
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9 The Northern Hemisphere experiences seasons
at different times than the Southern
Hemisphere does because A the Coriolis
effect produces winds B Earth tilts on its
axis C the Van Allen belt absorbs energy D
the equator receives direct sunlight
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10 Many weather systems form over oceans. The
energy needed to form these weather systems
originates from A water currents B
prevailing winds C the sun D the
moons gravity
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11 The photographs above show how a
change in climate is affecting the size of
Grinnell Glacier in Glacier National Park. Which
of the following best explains the change in
the glacier between 1910 and 1997? F Higher
average temperatures G Higher frequency of
earthquakes H Higher total precipitation J
Higher rates of wind erosion
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12 The lunar cycle is completed in about a
month because A the moon rotates once on
its axis B Earth revolves once around the
sun C the sun makes one full orbit D the
moon revolves once around Earth
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13 All of these will probably result when
atmospheric carbon dioxide levels increase
EXCEPT F increased plant growth G
elevated animal reproductive rates H greater
atmospheric pressures J higher average annual
temperatures
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14 Nitrogen fertilizer is often added to soil
to increase the growth of crops. Which of these
nearby ecosystems would most likely be harmed
by the use of nitrogen fertilizer? A
Forest B Pond C Park D Meadow
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15 The transfer of carbon that results from
burning fossil fuels will most likely affect
Earth in the future by F raising the
average global temperature G reducing
evaporation rates of ocean water H decreasing
the total mass of plant life J making air
transparent to ultraviolet light
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16 The lunar module weighed more on Earth
than it did on the moon because Earth has a
greater F gravitational force G
atmosphere H electromagnetic field J
density
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17 The picture shows sand used to
make a model of a galaxy. In the model, each
grain of sand best represents F a comet G
a black hole H an asteroid J a star
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18 Which of these processes contributes to
the growth of the Hawaiian island chain? A
Erosion B Glaciation C Sedimentation D
Volcanism
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19 Which of the following was most
likely caused by tectonic plates
colliding? A C Cavern
River B D
Lake Mountain
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20 Which diagram best represents the type of
plate movement that results in mountain
building? A C B
D
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21 Extinction is a natural event. Humans
greatly increase the rate of extinction because
humans are very effective at A causing
change B controlling weather C reducing
diseases D growing crops
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22 Several types of ground-nesting birds native
to Madagascar became extinct after humans
brought domestic cats to this large island.
This is an example of which kind of threat to
native animals? A Unregulated hunting B
Species introduction C Habitat
destruction D Foreign animal trade
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23 For which of these are people LEAST
responsible? A Smog B Ozone depletion C
Global warming D El Niño
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Forest Ecosystem 24 A direct
result of removing trees from the area above is
most likely A a higher rate of erosion B
a lower amount of carbon dioxide in the air C
a rapid increase in herbivore populations D a
slowdown of the nitrogen cycle
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25 At the quarry, soil was
removed to get to the rock layers underneath.
Which part of the environment was probably
least affected by this soil being removed? A
Air B Groundwater C Runoff water D
Plants
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Grade 8 Objective 5 Answer Key
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