Interactions of Living Things

Choose the letter of the best answer.

1. The ecosystem in the diagram enter the flower. How could this be
below has both biotic and abiotic an example of mutualism?
factors. A.if the spider is also eating part of
the flower
B.if the spider’s actions do not
affect the orchid plant
C.if the insects that the spider
captures are harming the flower
D.if the insects that the spider
captures are pollinating the
flower

Which is an abiotic factor in this

ecosystem?
A.fish
B.sand
C.snails
D.plants

2. Which of these statements best

describes a niche in an ecosystem?
A.the role of a species in its
population
B.the role of a species in its
community
C.the way a species uses the
resources in
its habitat
D.the way a species interacts with
other species in its habitat

3. A spider hides in an orchid flower.

It captures and eats insects as they

1
4. The diagram below shows some C.all populations that live in the
organisms that live in one kind of same area and interact
seaside ecosystem. D.all populations that live in the
same area but do not interact

6. Green plants use energy from the

sun to produce food during the
process of photosynthesis. This food
provides energy to an entire food
chain. What starting materials do
the plants use to make this food?
A.soil and water
B.water and oxygen
C.carbon dioxide and water
D.water, phosphorus, and nitrogen

7. Why are decomposers an essential

part of a healthy ecosystem?
A.Decomposers are a necessary
part of the diet of most
consumers.
B.Decomposers convert plant
Which of the following organisms
material into a form that primary
would benefit most from having
consumers can use.
patterns and coloration that help
them blend in with the sand-dune C.Decomposers make resources
grasses? available to producers by
breaking down waste materials.
A.crab
D.Decomposers extract energy from
B.sandpiper
sunlight as they break down
C.palm trees plant materials, adding returning
D.grasshopper energy to the system.
5. Which of the following describes a 8. What is one way that cooperation
community? helps lions to survive?
A.all populations that live in the A.They hunt in a group to increase
same area their likelihood of catching prey.
B.all populations that contain the B.They all have a tan color that
same species helps them blend into their

2
 environment. 9. The food web below shows some of
C.They eat a variety of prey, the feeding relationships among
including zebras, buffaloes, and organisms in Arctic waters.
wildebeest.
D.They live in prides of five to ten
adult females and their young,
and one or
two adult males.

Which organism would be least

affected by overfishing for cod in
Arctic waters?
A.seals
B.shrimp
C.baleen whales
D.toothed whales

10.A scientist is studying a population

of elephants contained in an animal
preserve. Which of the following
must be true if the size of the
population is increasing?
A.The birth rate has dropped to
zero.

3
B.The birth rate is equal to the
death rate.
C.The death rate is greater than the
birth rate.
D.The birth rate has become
greater than the death rate.

4
Introduction to Ecology
Choose the letter of the best answer.
1. Which of the following best
3. The following image shows
describes what scientists consider
organisms in a certain land biome.
when they study ecology?
A.the interactions of organisms
with their environment
B.the interactions of organisms
with weather and climate
C.the interactions of organisms to
reproduce and produce offspring
D.the interactions of organisms
with one another and the
environment
Which land biome is most likely
2. Which of the following determines shown in this image?
where a population can live?
A.desert
A.whether its needs are met by the
B.tundra
biotic factors in the habitat
C.tropical rain forest
B.whether its needs are met by the
abiotic factors in the habitat D.temperate grassland
C.whether its needs are met by the 4. Which of the following is a biotic
abiotic and biotic factors in the factor in an ecosystem?
habitat A.wind
D.whether its needs are met by the B.tree leaves
other populations of organisms in
the habitat C.small rocks
D.light from the sun

5. Which of these statements describes

a species?

5
 A.A species is a group of organisms C.A species is a group of organisms
that are closely related. that live in an area and interact.
B.A species is a group of organisms D.A species is a group of organisms
that live in the same habitat. that are closely related and
produce fertile offspring.

Roles in Energy Transfer

Choose the letter of the best answer.
1. Each organism has its own role in an ecosystem. Organisms can be producers, consumers, or
decomposers. Which of these organisms can be classified as a decomposer?

A.

B.

C.

D.

2. Which of the following consumers is a herbivore?

A.cat
B.horse
C.human
D.vulture

3. A student is identifying food chains in an ecosystem. Which of the following

organisms might be a tertiary consumer?

6
 A.frog
B.redwood tree
C.great white shark
D.athlete’s foot fungus

4. Two types of global food webs show the feeding relationships of organisms.
What distinguishes one type of global web from the other?

A.whether the producers are located on land or in water

B.whether or not the food web includes tertiary consumers
C.whether the web includes animals that migrate during the year
D.whether the ecosystem described by the web is localized or very broad

5. All organisms must obtain energy from their environment. Every organism
needs this energy in order to grow and reproduce. How do producers obtain
energy?
A.They obtain energy by eating plants, bacteria, and algae.
B.They extract chemical energy from decaying organic matter.
C.They extract energy from the chemicals in soil, air, and water.
D.They capture energy from sunlight and manufacture their own food.

Population Dynamics
Choose the letter of the best answer.
1. Which of the following is an example of a biotic limiting factor in an
ecosystem?
A.New predators move into the ecosystem.
B.A drought occurs for several months.
C.A hurricane passes through an ecosystem.
D.Living space is lost due to human activities.

2. Which of the following events would lead to an increase in the size of a

population of squirrels?
A.More squirrels are born than die.
B.Some squirrels emigrate in search of food.

7
 C.New predators are added to the ecosystem.
D.A large number of squirrels die because of a forest fire.

3. A scientist creates the following graph to demonstrate the effect of limiting

factors
on a population of rabbits.

According to the graph, during which year did the limiting factors in this
environment most affect the rabbit population?
A.Year 1
B.Year 2
C.Year 3
D.Year 4

4. Which statement provides an example of how social hierarchy might

influence a population?

A.Soldier termites defend the colony from predators.

B.Prairie dogs uses a high-pitched bark to communicate.
C.Mistletoe sends roots into tree branches to take in nutrients.
D.Poison tree frogs have bright colors signifying that they are toxic.

5. A scientist observes a population crash among eagles within an island

ecosystem. Which event might have led to such a crash?
A.Travelers brought new crops to the island.
B.A drop in sea level exposed more of the island.
C.The closing of a dam caused the island to flood.
D.Warm weather conditions resulted in an abundance of food.

8
Interactions in Communities
Choose the letter of the best answer.
1. Which of these statements best explains why trees in a forest do not grow very
close to one another?
A.Their seeds blow away from them.
B.Deer eat the newly sprouted seedlings.
C.Trees are harvested by lumber companies.
D.Trees compete for resources directly
around them.

2. Hermit crabs and anemones have a mutualistic relationship. Which of these

statements best describes how they interact?
A.Hermit crabs and anemones live in the same ecosystem and can eat similar
organisms.
B.Anemones can move on their own by using their tentacles and pedal disk.
The pedal disk is on the side of the anemone that is opposite its mouth.
C.Anemones cannot move very quickly, but they can sting predators. When
an anemone is riding on a hermit crab’s shell, the anemone protects the
crab from predators.
D.When a hermit crab grows too big for a shell, it moves to a larger shell. If
an anemone has attached itself to the old shell, the hermit crab will move
the anemone to its new shell.

3. One relationship between organisms is that of predator-prey. Which of the

following is the best description of a predator?
A.an organism that eats another organism
B.an organism that participates in symbiosis
C.an organism that is eaten by another organism
D.an organism that benefits at the expense of another organism

9
4. The diagram below shows feeding relationships among some organisms in an
ecosystem.

Based on the information shown in the diagram, which answer best describes
the relationship between hawks and coyotes?
A.Coyotes are parasites of hawks.
B.Coyotes are predators of hawks.
C.Coyotes and hawks are both prey.
D.Coyotes and hawks compete for the
same food.

5. Which of the following is an example of commensalism?

A.A bird is hunted, killed, and eaten by a cat.
B.A bird eats berries, then spreads the seeds.
C.A bird finds an existing hole in a tree and builds a nest in it.
D.A bird finds a small shellfish on a beach, cracks its shell, and eats it.

30
Population Dynamics
Climb the Pyramid: Population Ups and Downs
Climb the pyramid to show how much you know about population dynamics.
1. Work on your own, with a partner, or with a small group.

2. Choose one item from each layer of the pyramid. Check your choices.

3. Have your teacher approve your plan.

4. Submit or present your results.

__ Changing or Stable?
Write three equations. One
should show how a population
can increase in a year (this
would have a positive number
as its answer). One should
show how a population can
decrease in a year (with a
negative number as its
answer), and one should show
a stable population (with zero
as its answer).

__ High or Low? __ Crash Course!

Make two pictures, Write a paragraph that
either by drawing or describes why an
making a collage, of two ecosystem might have a
ecosystems. One should high carrying capacity
have a high carrying and why another might
capacity, and the other have a low carrying
should have a low capacity. Explain how the
carrying capacity. resources in each might
Explain why the carrying vary, and what might
capacity is high or low in cause a population to
each case. crash.

__ What’s the Limit? __ Cooperate or __ Best Pest Solution

Choose an ecosystem. Compete? Suppose you have a
Draw a bar graph that Draw two cartoons. One mosquito problem in your
shows the amount of should show competition neighborhood. Research
three abiotic and three between individuals in a and list several abiotic

31
biotic factors in the population. The other and biotic factors that
ecosystem. Indicate the should show cooperation you could use to reduce
limiting factor with an between individuals in a the mosquito population.
arrow and tell why it is population. Write a Which factor do you
the limiting factor. caption for each that think would work best,
tells the effect of the and why?
competition or
cooperation.

Unit 1: Interactions of Living Things

Vocabulary
Check the box to show whether each statement is true or false.

T F

  1.Competition occurs when organisms try to use the same limited

resource.

  2.Biomes are characterized by temperature, precipitation, and the plant

and animal communities that live there.

  3.A habitat is the role of a population in its community, including its

environment and its relationship with other species.

  4.A food chain is the feeding relationships among all of the organisms in
an ecosystem.

  5.A limiting factor is an environmental factor that increases the growth

of a population.

Analysis
1. Why is the energy of a food chain represented by a pyramid?
___________________________________________________________________
___________________________________________________________________
2. If an herbivore stores only 10 percent of the energy it takes in, what happens to the
remaining 90 percent?
___________________________________________________________________
___________________________________________________________________

32
3. What is present in the aquarium that has the function of recycling organic material,
such as waste?
___________________________________________________________________
4. In an ecosystem, where is the greatest amount of energy stored?
___________________________________________________________________
5. Where does the energy for this ecosystem originally come from?
___________________________________________________________________

Read each question below, and circle the best answer.

6. A small fish called a cleaner wrasse darts in and out of a larger fish’s
mouth, removing and eating parasites and dead tissue. Which term best
describes the relationship between the cleaner wrasse and the large fish?
A.mutualism C.parasitism
B.commensalismsD.competition
7. Bees have a society in which different members have different responsibilities.
The interaction among bees is an example of what type of behavior?
A.cooperation C.consumerism
B.competition D.commensalism

8. After a mild winter and plenty of food, a deer population grew rapidly. What
most likely happened to the wolf population in that same ecosystem?
A.It was unaffected. C. It shrunk.
B.It grew. D It went extinct.
9. The diagram below shows an aquatic ecosystem.

33
 What is one abiotic factor shown in this diagram?
A.the snails C.the crab
B.the water D.the tree roots
10. Which of the following is an example of a biotic limiting factor
for a population?
A.water availability C. disease
B.climate D.natural disasters
11.Which of the following is the most likely reason that a population might
crash?
A.The competition for the same resource suddenly drops.
B.The number of prey suddenly increases.
C.The number of predators suddenly decreases.
D.The carrying capacity of the environment suddenly drops.
12.Grizzly bears are classified in the order Carnivora. Their diet consists of
roots, tubers, berries, nuts, fungus, insects, rodents, and fish. What ecological
role best describes grizzly bears?
A.carnivores C.herbivores
B.omnivores D.producers

13. The graph below shows the size of a squirrel population

34
 over 20 years.

The trend displayed on the graph could be a result of what factor?

A.emigration C.increased death rate
B.immigration D.scarce resources

Critical Thin king

Answer the following questions in the space provided.
14.The diagram below shows how a manatee gets its energy.

What provides the energy for the sea grass, the manatee, and most life on
Earth? ____________________________________________________________.
What role does the sea grass play in this food chain?_____
According to this diagram, what type of consumer is the manatee?

Interactions of Living Things

Key Concepts
Choose the letter of the best answer.

35
1. A mangrove swamp contains many organisms living among the large roots of
the mangrove trees. This food web shows some of the relationships in that
ecosystem.

According to the food web, which organism is a producer in the mangrove

swamp?
A.crab
B.mold
C.pelican
D.phytoplankton

2. During the 1930s, a large region of the Great Plains experienced a drought
that turned grasslands into dust. How did this change most likely affect
populations of insects living among the grasslands?
A.They adapted to eat dust instead of grass.
B.They decreased because the resources they needed were not available.
C.They increased because other populations were eliminated from the
environment.
D.They were not affected because the size of a population cannot change over
time.

3. The image shows various things that make up a pond.

36
 Which things from the image make up the pond community?
A.water, rocks, clouds, and air only
B.fish, ducks, turtles, frogs, crayfish, and insects only
C.grasses, cattail reeds, fish, ducks, turtles, frogs, crayfish, and insects
D.grasses, cattail reeds, water, rocks, clouds, air, fish, ducks, turtles, frogs,
crayfish, and insects

4. Some consumers, such as many flying insects, need large amounts of energy to
grow and move from one place to another. How do consumers get energy to
function?
A.Consumers obtain all of their energy by eating other organisms.
B.Consumers obtain some energy from other organisms and some from
sunlight.
C.Consumers obtain most of their energy by absorbing it from their
environments.
D.Consumers convert light energy from the sun into chemical energy stored in
food.

5. How is an organism’s niche different from its habitat?

A.Its niche is the organism’s role within the habitat.
B.Its niche is the climate that exists within the habitat.
C.Its niche is the place where an organism lives within a habitat.
D.Its niche is the size of the population to which the organism belongs.

37
6. The graph below shows the populations of two different animals over a period
of time.

Which statement is most likely true of the kinds of animal represented by

animal A and animal B
in the graph?
A.A and B are both prey.
B.A and B are both predators.
C.A is prey, and B is a predator.
D.A is a predator, whereas B is prey.

7. Which of the following statements best describes the relationship between

ecosystems and biomes?
A.A biome may contain many ecosystems, and ecosystems within the same
biome are typically home to similar species of organisms.
B.An ecosystem may contain many biomes, and biomes within the same
ecosystem are typically home to similar species of organisms.
C.Both biomes and ecosystems are characterized by their climate conditions
and the communities that live in them; however, biomes refer to land
environments and ecosystems refer to aquatic environments.

38
 D.Both biomes and ecosystems are characterized by their climate conditions
and the communities that live in them; however, ecosystems refer to land
environments and biomes refer to aquatic environments.

8. Which of the following describes the relationship between a hermit crab and
the mollusk that previously lived in the hermit crab’s shell?
A.parasitism
B.mutualism
C.commensalism
D.predator and prey

9. What causes competition to occur in an environment?

A.Good conditions make resources plentiful.
B.Organisms struggle for a limited resource.
C.Members of a population have different roles.
D.A population falls below the environment’s carrying capacity.

10.What is the primary role of decomposers in an ecosystem?

A.to control the population of producers and consumers
B.to compete with producers for energy and other resources
C.to provide a source of energy for the producers in the ecosystem
D.to recycle energy and materials from dead producers and consumers

11.The figure below shows a food chain that might exist in a field or meadow.

Which of the following best describes what the food chain represents?
A.how an organism might change over time
B.the movement of organisms throughout the ecosystem
39
 C.the increase in size among organisms in the ecosystem
D.the path of energy transfer from producers to consumers

12.Which of the following is a resource for which two trees growing next to each
other in a forest would most likely compete?
A.nutrients in the soil
B.carbon dioxide in the air
C.bark-eating animals that live nearby
D.timber that humans can use for fuel

Critical Thinking
Answer the following questions in the space provided.
13.What is a limiting factor? How can limiting factors limit the size of a
population?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

Give an example of a biotic and an abiotic limiting factor in a forest

ecosystem.
___________________________________________________________________
___________________________________________________________________

Extended Response
Answer the following questions in the space provided.
14.An owl, grasshopper, grass plant, and shrew are all part of the same food
chain.
Describe what a food chain represents.
___________________________________________________________________
___________________________________________________________________

What would be the order of these organisms in a food chain?

___________________________________________________________________
___________________________________________________________________

40
 Which organism is the producer? Explain.
___________________________________________________________________
___________________________________________________________________

Which organism is a tertiary consumer? Explain.

___________________________________________________________________
___________________________________________________________________

15. Use the diagram to help you answer the following question.

If there is a decrease in food availability for the wading birds, how will the
different levels of organization shown in the diagram be affected?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

41
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
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___________________________________________________________________
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___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
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42
 ___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

ESSENTIAL QUESTIONS
Lessons 2 and 4
Answer the following question in the space provided.
16.The diagram below shows an example of a food web.

What are common traits of the prey animals shown that help them survive?
___________________________________________________________________
What important ecological group is missing from this food web?
What might happen if the rabbit population suddenly shrunk due to disease?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________

43
UNIT 2

Earth’s Biomes and Ecosystems

Choose the letter of the best answer.
1. What happens when an ecosystem undergoes eutrophication?
A.An exotic species is introduced into a region.
B.The density of people living in an area increases.
C.The pH of a body of water drops below normal levels.
D.The amount of nutrients in an aquatic ecosystem increases.

2. Which phrase best describes the soil in a grassland biome?

A.dry and frozen
B.rocky, sandy, and dry
C.deep, dark, and nutrient rich
D.thin, acidic, and nutrient poor

3. The diagram shows a person commuting to work.

44
 Which of the following best describes what the person is doing?
A.recycling natural resources
B.depleting natural resources
C.conserving natural resources
D.identifying new natural resources

4. Which of the following would most likely be a pioneer species as an area

undergoes succession?
A.mosses
B. squirrels
C.plankton
D.coniferous trees

5. The following table lists the number and variety of organisms in four different
ecosystems.
Plants Animals
# of # of # of # of
Orga Spe Orga Spe
nism cies nism cies
s s
Ecosy 500 5 300 4
stem
1
Ecosy 300 10 100 7
stem
2
Ecosy 100 2 200 5
stem
3
Ecosy 50 6 30 4
stem
4
Based on the table, which ecosystem is likely the most sustainable?

45
 A.Ecosystem 1
B.Ecosystem 2
C.Ecosystem 3
D.Ecosystem 4

6. Coral reefs and kelp forests are both found in coastal ocean ecosystems. How
are the ecosystems in which they are found different?
A.Coral reefs are found in warm waters and kelp forests are found in cold
waters.
B.Coral reefs are found in salt water and kelp forests are found in fresh
water.
C.Coral reefs are found above the tide line and kelp forests are found below
the tide line.
D.Coral reefs are found in water exposed to sunlight and kelp forests get their
energy from chemicals along the ocean floor.

46
7. Which term best describes a body of water that forms where a river flows into
an ocean?
A.bog
B.estuary
C.swamp
D.wetland

8. What is one way that a temperate rain forest is different from a temperate
deciduous forest?
A.A temperate rain forest has large populations of grasses rather than tall
trees.
B.A temperate rain forest is made up of palm trees rather than coniferous
trees.
C.A temperate rain forest has a long rainy season rather than moderate, year-
round rainfall.
D.A temperate rain forest has trees that lose their leaves in winter rather than
keeping them year-round.

9. The diagram below shows an outline of Earth.

At which location is a tropical rain forest biome most likely to be located?

A.Location 1
B.Location 2
C.Location 3
D.Location 4
10.Worms break down dead plants in the soil to release nutrients. Which
property of nutrients shows that they are matter?
A.Nutrients are warm.
B.Nutrients have mass.
C.Nutrients can do work.
D.Nutrients contain energy.

Land Biomes
Choose the letter of the best answer.
1. In which biome would you expect to find many coniferous trees?
A.taiga
B.tundra
C.savanna
D.tropical rain forest

2. What important role does fire play in a grassland biome?

A.It helps seeds germinate.
B.It spreads seeds to distant locations.
C.It causes flowers on plants to bloom.
D.It prevents animals from eating plant populations.

3. How are tropical plants such as bromeliads adapted to the biome in which
they live?
A.They grow from tree branches rather than the forest floor, which helps
them to absorb more sunlight.
B.They have long, thick roots, which helps them to gather the nutrients that
are found deep within the soil.
C.They have hollow leaves and stems for storing water, which helps them to
survive long periods with little rainfall.
D.They lose their leaves during the winter, which helps them to save energy
when the temperature falls and prevents the buildup
of snow.
 Unit 2 Lesson 2

4. How is a tundra biome similar to a desert biome?

A.Both biomes have dry, rocky soils.
B.Both biomes lack plants or animals.
C.Both biomes are hot during the day and cold at night.
D.Both biomes are characterized by very little precipitation.

5. A researcher is investigating the plants shown below.

Which biome is the researcher most likely studying?

A.taiga
B.desert
C.grassland
D.tropical rain forest
 Unit 2 Lesson 2

Aquatic Ecosystems
Choose the letter of the best answer.
1. Which statement about the deep ocean zone is true?
A.Plankton dominate this zone of the ocean.
B.Coral reefs are commonly found in this zone.
C.Organisms in this zone must be able to survive major changes in salinity.
D.Some organisms in this zone use chemicals for energy rather than sunlight.

2. Which example represents an abiotic factor in an aquatic ecosystem?

A.Water lilies float on top of a pond.
B.A population of bass is living in a lake.
C.The pH of a lake is decreased by acid rain.
D.Dragonflies feed on small insects near a pond.

3. How do rivers and streams differ from lakes and ponds?

A.Rivers and streams are made up of salt water instead of fresh water.
B.Unlike the water in lakes and ponds, the water in rivers and streams flows.
C.Fish can live in rivers and streams, whereas plants grow in lakes and ponds.
D.Lakes and ponds form only after heavy rains, whereas rivers and streams
always exist.

4. The illustration below shows a river otter.

What is one way the otter is adapted to living in the moving water of a river?
A.It has sharp claws.
 Unit 2 Lesson 2

B.It has long whiskers.

C.It has a streamlined body.
D.It has an Earth-toned color.

5. Which ocean zone is at the deepest location?

A.neritic zone
B.bathyal zone
C.abyssal zone
D.intertidal zone

Energy and Matter in Ecosystems

Choose the letter of the best answer.
1. Carbon exists in many forms on C.Animals are converting carbon
Earth. The diagram below shows dioxide from the atmosphere to
part of the carbon cycle. oxygen.
D.Animals are breaking down
organic molecules and releasing
carbon dioxide into the
atmosphere.

2. A scientist is studying a substance

that is cycled through ecosystems.
Which of the following substances
might the scientist be studying?
A.soil
B.copper
C.glucose
D.nitrogen

What is happening in Step 1?

A.Animals are decomposing and
releasing carbon into the soil.
B.Animals are releasing energy into
the environment and storing
carbon.
 Unit 2 Lesson 2

3. What is energy? D.between Earth’s surface and

A.the ability to do work underground aquifers
B.anything that has mass 5. Which phrase best describes a
C.anything that takes up space consumer in an ecosystem?
D.the ability to conduct current A.an organism that is at the bottom
of the food chain
4. Where does the majority of
B.an organism that breaks down
evaporation on
dead plants and animals
Earth occur?
C.an organism that gets its energy
A.between rivers and oceans
by eating plants or animals
B.between the oceans and the
D.an organism that converts light
atmosphere
energy into chemical energy
C.between the ground and the
atmosphere
 Unit 2 Lesson 2

Changes in Ecosystems
Choose the letter of the best answer.
1. How is secondary succession B.They constantly change in
different from primary succession? different ways over time.
A.Secondary succession occurs C.Ecosystems always revert back to
after a disturbance in an area their original state.
that was previously uninhabited. D.Each ecosystem can exist for only
B.Secondary succession occurs a specific length of time.
after a disturbance in an area in
which the soil has remained
intact.
C.Secondary succession occurs over
a longer period of time than
primary succession.
D.Secondary succession occurs
when animals are introduced to
an area that had only plants.

2. How do pioneer species make

ecological succession possible on an
island formed from volcanic
eruptions?
A.They use chemicals to produce
food.
B.They establish homes in which
animals can live.
C.They break down rock into soil in
which plants can grow.
D.They adjust the climate by
altering the average temperature
in a region.

3. Which statement best describes

ecosystems?
A.They can never change once they
are established.
 Unit 2 Lesson 2

4. Which term best describes the

number and variety of organisms in
a given area during a specific
period of time?
A.carrying capacity
B.biodiversity
C.succession
D.eutrophication

5. The diagram shows changes to a

pond ecosystem over time.

Through which of the following

processes are plant communities
taking over the ecosystem?
A.acidification
B.primary succession
C.climate disturbance
D.natural eutrophication
 Unit 2 Lesson 2

Analysis
2. Does the community shown in the illustrations represent an example of
primary or secondary succession? Explain.
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3. Will this community continue to undergo change beyond the last stage shown
in your group of illustrations? Explain.
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4. A student says that it would take about ten years for the community to go
from the first stage to the last stage shown in the illustrations. Do you agree?
Explain.
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5. How would the last three illustrations be different if a fire had destroyed the
community half-way through the stages shown?
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6. Describe one plant that is present at one stage but is absent or present in very
low abundance at another stage. Explain why its presence in the community
changes.
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 Unit 2 Lesson 2

Unit 2: Earth's Biomes and Ecosystems

Fill in each blank with the term that best completes the following sentences.
1. The ________________________ states that energy cannot be created or
destroyed.
2. A ________________________ is a community of organisms at a major
regional or global level.
3. A ________________________ tree has leaves that drop in the winter as an
adaptation to cold temperatures.
4. ________________________ is an increase in the ratio or density of people
living in urban areas rather than rural areas.
5. A ________________________ is one of the first species of organisms to live in
an area.

Key Concepts
Read each question below, and circle the best answer.
6. Where do producers that use chloroplasts get the energy they need to survive?
A.from the sun C.from the organisms they eat
B.from the air D.from the remains of organisms
7. What are the ocean zones of a marine ecosystem, from most shallow to
deepest?
A.intertidal, neritic, bathyal, abyssal
B.abyssal, neritic, intertidal, bathyal
C.neritic, intertidal, bathyal, abyssal
D.bathyal, abyssal, intertidal, neritic

8. Resource depletion, pollution, and habitat loss are all environmental

problems caused by what factor?
A.acid rain C.introduced species
B.eutrophication D.human activities
9. Below is an energy pyramid diagram.

Why is the level at 4 so much smaller than the level at 1?

A.Organisms gain energy as the food chain moves down the pyramid.
B.Fewer organisms are supported as you move down the pyramid.
C.Only the energy that is used is available to organisms at a higher level.
D.Only the energy that is stored is available to organisms at a higher level.
10.What element can be changed by lightning into a form that plants can use?
A.oxygen C.phosphorous
B.carbon D.nitrogen
11.Below is a diagram of the carbon cycle.

Which number corresponds to combustion and the release of CO2, water, and
the loss of energy as heat into the environment?
A.1 C.3
B.2 D.4
12.What is an adaptation that allows some animals to survive in the tundra?
A.living underground C. being active at night only
B.having thick layers of fur D. living within the upper branches of trees
13.Some grass species need fire in order for their seeds to germinate. Why might
this adaptation be useful for grasses?
A.Fire allows trees to grow and provide shade for the grasses.
B.The hot temperature of the fire helps the grasses grow faster.
C.Seeds can germinate in an area that has been cleared by a fire.
D.Fire discourages grazing by large animals so grass can grow higher.

Critical Thin king

Answer the following questions in the space provided.
14.Draw a diagram of the water cycle and label it with the terms given below.

In the space provided, identify what each term means.

Precipitation: __________________________________________
Evaporation: ___________________________________________
Transpiration: _________________________________________
Condensation: __________________________________________
15.The picture below shows a land ecosystem that experiences annual flooding.

Is this ecosystem more likely a result of primary succession or secondary

succession? ________________________________________________________
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Predict what would happen if a fast growing non-native species of plant was
introduced to this ecosystem.
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 ESSENTIAL QUESTIONS
Lessons 2 and 5
Answer the following question in the space provided.
16.Below is an example of an aquatic food web common in mangrove forests.

Mangroves commonly grow in estuaries. What are the characteristics of an

estuary?____________________________________________________________
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What might happen if the prawns and fish shown in the diagram were fished
to near extinction?___________________________________________________
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Earth’s Biomes and Ecosystems

Key Concepts
Choose the letter of the best answer.
1. Which of the following is not a category of aquatic ecosystem?
A.aquifer
B.estuary
C.freshwater
D.saltwater

2. The diagram below shows an energy pyramid. In a marine ecosystem, algae

carry out photosynthesis. Barracuda eat snapper fish. Reef sharks eat
barracuda.

Which organism would be at the top of the energy pyramid?

A.algae
B.reef shark
C.barracuda
D.snapper fish

3. What happens when resource depletion occurs?

A.chemicals are spilled or dumped into water
B.nutrients are added to an aquatic ecosystem
C.a large fraction of a specific resource is used up
D.materials are changed in form so they can be reused
4. The amount of available energy decreases along a food chain in an ecosystem.
How is this explained by the law of conservation of energy?
A.Living things change energy into matter.
B.The energy is changed to a different form.
C.Only small amounts of energy can be destroyed at a time.
D.Energy is used up when living things conduct life processes.

5. How does natural eutrophication affect a pond ecosystem?

A.It causes nutrients to build up.
B.It causes temperatures to rise.
C.It causes the pond to become deeper.
D.It causes a change in the flow of water.

6. The diagram below shows changes occurring in an ecosystem over time.

What is happening in the diagram?

A.Plants are growing larger over time.
B.Soil is being removed from an ecosystem over time.
C.An ecosystem is slowly being eliminated from a region.
D.Biological communities are gradually being replaced by other communities.

7. Which of the following human activities is most likely to affect water quantity
in an area?
A.boating on a lake
B.constructing a dam
C.dumping chemicals down a drain
D.piloting oil tankers across the ocean
8. Which ecosystem most likely has the greatest biological diversity?
A.a tank that includes several goldfish
B.a tundra region that has many penguins
C.a pine tree in which three groups of birds live
D.a rain forest that has many different types of plants and animals

9. The picture shows an arctic fox.

In which biome does the fox most likely live?

A.desert
B.tundra
C.grasslands
D.temperature rain forest

10.Which is an example of a biome?

A.a cave
B.an old tree
C.a large lake
D.a tropical rain forest
11.The diagram below shows the four zones of the ocean.

Which part of the diagram represents the intertidal zone?

A.Zone 1
B.Zone 2
C.Zone 3
D.Zone 4

12.Which adaptation would best help a lily pad survive in the moving water of a
stream?
A.long roots
B.large leaves
C.sweet scent
D.white flowers

Critical Thinking
Answer the following questions in the space provided.
13.What is conservation?
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What are several ways of practicing conservation?

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Extended Response
Answer the following questions in the space provided.
14.Where are two places that carbon is found in the environment?
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How is carbon involved in the process of photosynthesis?

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How is carbon involved in the process of cellular respiration?

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How is carbon involved in the process of decomposition?

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