SMS Science Grade 8 Unit12: Ecosystems
Some questions (c) 2012 by CSCOPE.
Some questions (c) 2012 by Region 10 Educational Service Center.
Some questions (c) 2012 by NWEA.
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1
The Barton Springs salamander lives
only at the spring outflows of Barton
Springs near Austin, Texas. They are
often found under rocks or among gravel
in water several inches to 15 feet deep.
They can also be found hiding in aquatic
plants and algae. They rely on a clear,
clean, continuous flow of spring water.
They are known to eat amphipods (tiny
aquatic crustaceans) and other small
aquatic animals. The Barton Springs
salamander is clearly capable of living
underground, but also inhabits surface
environments.
What is the MOST likely way that
humans could have a damaging impact
on the Barton Springs salamander?
2 Fossils of tropical plants and animals can
be found buried in limestone rock in the
North Texas area. These plants and
animals are no longer found in this
region. What is the most likely cause of
the disappearance of these tropical
plants and animals?
A Earthquakes and volcanoes
destroyed all the tropical plants and
animals.
B Tropical animals ate all the tropical
plants and everything died out.
C
Air pollution and acid rain killed off
all the tropical plants and animals.
D The climate in that area is different
today than when tropical plants and
animals lived there.
A polluting the water
B floating down the river
C
adding new water vegetation
D adding new crustaceans
3
Which of the following is the MOST
likely negative effect of damming rivers
to supply hydroelectric energy?
A increased fossil fuel costs
B loss of fish habitat
C
decreased use of electricity
D higher levels of air pollution
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4 Which is an abiotic factor that most limits the number of frogs living in a
pond?
A the color of the water
B the number of predators
C
the temperature of the water
D the populations of producers
5
How will a thriving grassland ecosystem most likely be affected by a drought?
A Plant respiration will increase.
B Animals will be forced to migrate.
C
Soil nutrients will be enriched.
D Natural succession will cease.
6 Which of the following is NOT an
example of how biotic factors interact
with abiotic factors in an ecosystem?
B Plants remove carbon dioxide from
the air and add oxygen.
Plants need sunlight to perform
photosynthesis. In the tropical
rainforest, the survival of a plant
depends upon its ability to adapt in
order to reach sunlight. Which of the
following is an example of one such
adaptation?
C
A vines that wrap around a tree
A A lion preys on a herd of gazelle.
Animals cause erosion by digging in
the dirt.
D A lizard raises its body temperature
by using heat from the Sun.
7
B thin, shallow roots that run across
the forest floor
C
numerous small leaves on one stem
D colorful petals
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8 A company purchased a large forest and
cut the trees for lumber. Sunlight which
had not reached the forest floor before
was now very bright on the bare ground.
Holly ferns began to grow rapidly
because of increased access to light and
moisture. Which population of organisms
would be in direct competition with the
Holly ferns for the same resources?
A spotted owls
B squirrels
C
hawks
D wildflowers
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9 The relationship between an owl and a mouse is a
A parasite­host relationship.
B symbiotic relationship.
C
mutualistic relationship.
D predator­prey relationship.
10
An ecosystem is a community of
organisms interacting with their
physical environment. Why are
decomposers an important part
of ecosystems?
A They break down dead organisms
to return nutrients to the soil.
B They produce their own food for
survival.
C
They play a role in preventing
weathering and erosion.
D They provide most of the energy to
consumers.
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11
Some wasp species lay their eggs inside living caterpillars. As the eggs
mature, they use the caterpillar as a food resource. Eventually, the wasp
larvae hatch out of the caterpillar. This type of relationship is best described
as
A predator­prey.
B parasitic.
C
mutualistic.
D commensalistic.
12
Tapeworms live in the intestines of dogs and absorb nutrients from food the
dog eats. Which best describes the outcome of this relationship?
A The dog and tapeworm both become ill.
B The dog becomes ill, and the tapeworm benefits.
C
The tapeworm and dog help each other survive.
D The tapeworm helps the dog survive.
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13
+
In a food web, the numbers of each organism typically exist in a relatively stable
proportion. If an oil spill killed a large amount of zooplankton, what would be the next
thing that would happen?
A The number of tiger sharks would decrease.
B The number of phytoplankton would increase.
C
The number of clams, mackerels, and jellyfish would decrease.
D The number of herring, whelk, squids, and loggerhead turtles would increase.
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14
The development and use of new chemical fertilizers has improved the yield
of agricultural crops. Which of the following is the most likely disadvantage
of using chemical fertilizers?
A Runoff containing fertilizer may contaminate nearby surface water.
B Increased agricultural crops may promote insect overpopulation.
C
Improved crop output may cause excess carbon dioxide production.
D Excess fertilizer may cause increased weed populations.
15
When oil rigs are finished drilling, the
platforms are sunk into the ocean.
These platforms create an artificial reef
area. Which of the following life forms
would be the first to inhabit the area?
A sharks
16
Fossils of tropical plants have been
found in coal mines in the North
Eastern United States. This type of
plant is no longer found in this region of
the US. What is the most likely cause of
the disappearance of tropical plants in
the Northeast?
B large fish
C
small fish
D plankton
A Volcanic activity in the Northeast
caused the tropical plants to die.
B The area is so heavily populated
that diverse plant growth is no
longer found.
C
Air pollution and acid rain changed
the pH of the soil and caused the
tropical plants to die.
D The climate of the area is different
than it was when tropical plants
were common.
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17
+ A scientist made the drawings above to show how the root structures of a plant species
changed over time. Based on these drawings, the plant species MOST LIKELY lived in an
area that changed from —
A mountaintop into a hill
B rainforest into a tundra
C
grassland into a desert
D desert into a tundra
18
In some communities, forests are cleared through burning, and the
deforested land is used for farming. Which of these is a negative consequence
of this practice?
A decreased plant and animal diversity
B increased availability of soil nutrients
C
greater access to water for plants and animals
D less sunlight reaching the ground
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19
In the 1800s, domesticated rabbits from Europe were brought to Australia.
The rabbit population increased so quickly that it caused severe damage to
agriculture and the natural environment. Even though scientists have tried
to reduce the rabbit population, it continues to be a problem today. Which
statement is the best conclusion from this series of events?
A Human actions can lead to imbalances in ecosystems.
B Humans use technology to help organisms adapt to new areas.
C
Rabbit populations decrease when they are placed in new areas.
D Rabbits from other continents cannot survive in different ecosystems.
20
American alligators inhabit nearly every natural body of water in Florida.
Which best describes the effect that draining of wetlands and building of
canals has on American alligators?
A American alligators have found new saltwater habitats.
B American alligators have fewer trophic levels to support them.
C
American alligators have adapted to changes in their habitats.
D American alligator have become producers in saltwater environments.
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21
The growing human population has many practices that adversely impact
the environment. Acid rain is one example of environmental damage that is
related to human activities. Which human activity is most likely the largest
contributor to acid rain?
A burning fossil fuels in power plants
B using pesticides on agricultural crops
C
dumping waste matter into ocean waters
D clearing native forests for industrialization
22
Farmers in Wyoming were concerned because some of their chickens were
being preyed upon by hawks that lived in areas around their ranches. The
farmers grouped together and hunted the hawks until they were no longer in
their area. Which would most likely happen next?
A The chicken population would go down.
B Populations of mice and rats would increase.
C
Another bird of prey would replace the hawk.
D The chickens would have a lower rate of disease.
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23
A marsh food chain is shown.
According to the food chain, how would an increase in the toad population
most likely affect the other populations?
A The grass population would decrease.
B The hawk population would decrease.
C
The snake population would decrease.
D The grasshopper population would decrease.
24
Some plants rely on hummingbirds for pollination. If a deadly disease
infected the hummingbird population, what would most likely happen to the
plants?
A They would die within hours.
B They would become endangered.
C
They would need to migrate.
D They would grow at a slower rate.
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25
A particular type of bird carries the
genes for its offspring to either have a
short, strong beak or a long beak. The
strong beak is great for crushing nuts,
while the longer beak is used to get to
water in little spaces. Normally, 75%
of the bird population have short,
strong beaks while only 25% have long
beaks. If the area in which the birds
live experiences a 10­year drought,
what change in beak type could be
expected in the population?
26
Large forest fires, started by lightning,
have been common in parts of the
Western and Northwestern United
States in the past few years. The forest
ecosystem is changed by this natural
disaster. In addition to the loss of
property, there are other ways that
forest fires affect the environment.
Which of the following is a result of a
large forest fire?
A Carbon dioxide in the atmosphere
decreases.
A More birds would have a short
beak.
B Mudslides cover roads and river
valleys after heavy rain.
B More birds would have a long
beak.
C
Wildlife populations increase.
D Soil becomes less fertile.
C
The beaks would not change.
D The adult birds would stay the
same, but baby birds would all
have longer beaks.
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27
In a forest ecosystem, the squirrels eat seeds from trees. The squirrels are
then eaten by hawks, owls, and foxes. If there were no more owls present in
this ecosystem, which would most likely happen in the forest?
A The squirrel population would increase.
B The hawk population would decrease.
C
The fox population would decrease.
D The tree population would increase.
28
Clownfish take shelter in the tentacles of sea anemones, and keep sea
anemones clean. Which type of relationship does this represent?
A parasitism
B commensalism
C
mutualism
D neutralism
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