Deck 23: Ecological Communities

Question 1

Do humans exhibit any mutualistic relationships?

A)No; humans can only develop parasitic relationships with other organisms.
B)Yes; humans host disease pathogens that limit population growth and overcrowding.
C)No; humans are unable to form mutualistic relationships with other organisms.
D)Yes; humans host beneficial bacteria within our digestive systems.

Answer 1

D

Question 2

In seed-dispersal mutualism, plants produce _____ to entice consumers to disperse the plant's seeds.

A)attractive aromas
B)fleshy fruits
C)edible pollen
D)nectar

Answer 2

B

Question 3

An animal eats fruit from a plant and later deposits seed in its feces far from the plant. This is an example of a

A)pollinator mutualism.
B)gut inhabitant mutualism.
C)behavioral mutualism.
D)none of the above

Answer 3

D

Question 4

The corals in tropical reefs have a mutualistic relationship with

A)algae.
B)clown fish.
C)triggerfish.
D)shrimp.

Question 5

Which of the following animals would be most likely to simultaneously participate in seed dispersal and a gut inhabitant mutualism?

A)wolves
B)rattlesnakes
C)scorpions
D)deer

Question 6

Which of the following symbols represents a mutualistic relationship?

A)+/-
B)+/+
C)o/+
D)-/-

Question 7

A lichen is growing on a tree trunk. The lichen gains height and exposure to sunlight for photosynthesis. The tree is not harmed by the lichen but does not benefit either. The relationship between the lichen and the tree is

A)commensalism.
B)mutualism.
C)parasitism.
D)interference competition.

Question 8

Antibiotic therapy sometimes reduces the population of gut-inhabiting microorganisms. Bloating and diarrhea often follow until the populations reestablish themselves. This observation suggests that these microorganisms participate in a(n)_____ relationship with humans.

A)competitive
B)exploitative
C)mutualistic
D)pathogenic

Question 9

The relationship between house pets and people would be best described as

A)parasitic.
B)mutualistic.
C)predatorial.
D)competitive.

Question 10

Which of the following combinations of symbols represents an interaction in which one species benefits and the other is exploited?

A)+/-
B)+/+
C)o/+
D)-/-

Question 11

Every healthy human digestive system is home to countless microorganisms. In a normal digestive system, what type of relationship would you say this is?

A)parasitic
B)mutualistic
C)competitive
D)pathological

Question 12

Relationships between different species often involve energy or lifestyle compromises. What best describes the compromises, if any, seen in mutualism?

A)no compromises to either organism
B)fatal to at least one of the organisms
C)a compromise to one organism but not the other
D)slight compromises to both organisms

Question 13

Which of the following symbols represents a commensalistic relationship?

A)+/-
B)+/+
C)o/+
D)-/-

Question 14

Some algae and fungi live in associations known as lichens, which allow both to survive in a harsher environment than either could normally live in alone. This association is an example of

A)parasitism.
B)mutualism.
C)consumerism.
D)competition.

Question 15

As the figure below illustrates, communities vary tremendously in size from as large as an entire forest to the digestive system of a single deer.
How do biologists recognize communities?

A)Communities have no fixed boundaries; their sizes are simply defined according to what is convenient at a given point in time.
B)Communities can be nested within a larger one; for example, the deer is part of the woodland, which is part of the forest.
C)Communities are characterized by their species composition.
D)All of the above are used to recognize communities.

Question 16

Clown fish have evolved to live safely between the stinging tentacles of certain sea anemones. The fish receives protection from predators, whereas the anemone receives some food from the fish. This relationship is an example of

A)nutritional mutualism.
B)consumer interaction.
C)competitive limitation.
D)behavioral mutualism.

Question 17

Which of the following best illustrates behavioral mutualism?

A)Fruit seeds pass through a consumer's digestive system and are moved to a location distant from the parent plant.
B)Pollen from one plant is carried to another.
C)Small fish called cleaner wrasse remove parasites from the mouth and gills of predatory fish.
D)Infected individuals experience diarrhea that releases infectious organisms into the environment.

Question 18

In the pollinator mutualism between the yucca plant and the yucca moth, the yucca plant is able to abort the seeds in any given flower if the moth lays too many eggs in that flower. What is the advantage the yucca plant gains by aborting these seeds?

A)The yucca plant is responsible for keeping the yucca moth population at a reasonable size.
B)Seeds are energetically expensive to produce, and if the moth larvae are going to eat most of the seeds in one fruit, the plant is able to save energy by aborting those seeds.
C)The carrying capacity of the yucca moth is increased every time it lays an egg in a yucca plant's flower, so the fewer seeds that are produced by the plant, the higher the carrying capacity of the moth can be.
D)The carrying capacity of the yucca moth is reduced every time it lays an egg in a yucca plant's flower, so the fewer seeds that are produced by the plant, the higher the carrying capacity of the moth can be.

Question 19

Can a human being be considered an ecological community?

A)Yes; for example, a community of microorganisms lives within the human digestive system.
B)Yes; human beings live with other humans, own pets, and grow domesticated crops.
C)No; a community is formed from many populations and it takes more than one individual to make up a population.
D)No; human populations are artificial rather than natural, and are considered to fall outside of ecology.

Question 20

Human cells contain mitochondria, which are responsible for processing the energy needed by our cells. Remember that the ancestors of mitochondria may once have been free-living prokaryotes. If mitochondria were still considered to be separate organisms within our cells, which of the following would best describe our relationship with them?

A)parasitic
B)mutualistic
C)competitive
D)pathogenic

Question 21

The relationship between humans and domesticated livestock is

A)symbiotic and competitive.
B)parasitic and predatory.
C)competitive and symbiotic.
D)predator and prey.

Question 22

Which of the following symbols represents a competitive interaction?

A)+/-
B)+/+
C)o/+
D)-/-

Question 23

Coevolution often occurs when natural selection produces evolutionary change in predator and prey populations; a good example is

A)the exceptionally high toxicity of the rough-skinned newt.
B)the speed capacities of the cheetah and Thompson's gazelle.
C)hummingbird bill length and flower corolla lengths.
D)all of the above

Question 24

Female ducks frequently deposit fertile eggs in the nests of unattended neighboring ducks. These eggs hatch and are then reared by the foster parent. What term best describes this behavior?

A)parasitism
B)behavioral mutualism
C)exploitative competition
D)nest mutualism

Question 25

In _____ competition, species compete indirectly for a shared resource, each reducing the amount available to the other competitor.

A)exploitative
B)restrictive
C)interference
D)advantageous

Question 26

What statement best describes a parasitic relationship?

A)Both the parasite and the host benefit.
B)Only the parasite benefits; the host is harmed.
C)Only the host benefits; the parasite is harmed.
D)Both the parasite and the host are harmed.

Question 27

Which of the following statements is false?

A)Predators can drive their prey to extinction.
B)Predators can cause the abundance of their prey to rise.
C)Predators can alter the behavior of their prey.
D)Predators can restrict the distribution of their prey.

Question 28

Flies belonging to the family Phoridae inject their eggs into fire ants. A larva that hatches from the egg devours the ant from the inside. The larva would be called a

A)parasite.
B)gut mutualist.
C)predator.
D)pathogen.

Question 29

Which of the following statements about competition is false?

A)It can limit the distribution of a species.
B)It can limit the abundance of a species.
C)It can increase the differences between species.
D)It can make two species become more alike.

Question 30

Which of the following could be an example of an induced response?

A)bright colors on a caterpillar
B)spines on a cactus
C)brightly colored flowers on a rosebush
D)color patterns on a poisonous snake

Question 31

Cowbirds lay their eggs in the nests of smaller birds. The fast-developing cowbird chicks hatch first, then push the other baby chicks out of the nest as they hatch. Which interaction best describes cowbird behavior?

A)mutualism
B)parasitism
C)predation
D)exploitative competition

Question 32

The relationship among plants growing in a woodland and living in high density with limited resources can best be described as

A)pollinator mutualistic.
B)parasitic.
C)symbiotic.
D)competitive.

Question 33

A praying mantis captures and devours many pest insects. The relationship between a mantis and a grasshopper it is eating is one of

A)parasite/host.
B)pathogen/prey.
C)parasite/prey.
D)predator/prey.

Question 34

Beech drops are plants that no longer photosynthesize. They obtain nutrition by extending their roots into a beech tree and intercepting the flow of sap. Beech drops would be considered a _____ of beech trees.

A)parasite
B)predator
C)host
D)mutual partner

Question 35

Examine the graph below.
Research indicates that goshawk predation is much less effective when prey species, like wood pigeons, are in large flocks. This is true because

A)large flocks are just temporary aggregations of several small flocks.
B)large prey flocks may be able to better provide advance warning of predators.
C)predatory birds are generally afraid of large prey flocks and will not attack birds in them.
D)small flocks are more likely to have parasites that change behaviors, making the prey more susceptible to predation.

Question 36

A tapeworm is living in the intestine of a human and absorbing nutrients. This relationship is one of

A)pathogen/prey.
B)pathogen/host.
C)parasite/host.
D)predator/host.

Question 37

If an animal is an herbivore, does that mean it cannot have interactions with organisms other than the plants it eats?

A)No; an herbivore might also have a mutualistic relationship with, for instance, intestinal bacteria.
B)No; an herbivore could be prey in predator/prey interactions.
C)Yes; natural selection predicts a single relationship strategy will eventually emerge with the greatest fitness.
D)both a and b

Question 38

Pathogens are considered a special type of parasite because they

A)invariably kill their prey.
B)affect specific portions of the host.
C)cause disease in their hosts.
D)live on or in the host organism.

Question 39

Suppose that two species of hummingbirds have very similar tongue lengths in regions where only one of the two species occurs, but that one species has a shorter tongue and the other a longer tongue in regions where both species occur. This would most likely be an example of

A)seed-dispersal mutualism.
B)parasitism.
C)character displacement.
D)a predator/prey interaction.

Question 40

Which of the following symbols represents a parasitic relationship?

A)+/-
B)+/+
C)o/+
D)-/-

Question 41

Pancake batter consists of flour, eggs, butter, salt, baking powder, sugar, and milk. When we eat pancakes, we are acting as

A)secondary and tertiary consumers.
B)producers and secondary consumers.
C)primary and tertiary consumers.
D)primary and secondary consumers.

Question 42

In a typical prairie food web, energy moves from grass to grasshopper to field mouse to fox. Which organism is the secondary consumer?

A)the grass
B)the grasshopper
C)the mouse
D)the fox

Question 43

Which of the following organisms is a producer?

A)fungus
B)human
C)cow
D)grass

Question 44

Which of the following is not a producer in an aquatic biome?

A)algae
B)mussels
C)phytoplankton
D)bacteria

Question 45

Which example best illustrates interference competition?

A)Soil levels of potassium are gradually reduced by the hemlocks and cedars in a climax forest.
B)The growth of starling populations usually coincides with declines in song birds because both use abandoned cavities for nesting.
C)When larger animals become scarce, wolves often prey on mice, reducing their availability to coyotes.
D)Rough-skinned newts contain enough toxin in their skin glands to kill almost any predator.

Question 46

The activity of predators has caused their prey to evolve a variety of protective characteristics. How were the prey able to acquire these new features?

A)The prey selectively bred in order to increase the frequency of protective traits in their population.
B)The prey underwent a population explosion that allowed them to outnumber their predators and thus develop new protective features.
C)The prey organisms mated with other species in order to acquire new protective traits.
D)Natural selection acted on genetic variability already present in the prey population.

Question 47

In a typical prairie food web, energy moves from grass to grasshopper to field mouse to fox. Which organism is the primary consumer?

A)the grass
B)the grasshopper
C)the mouse
D)the fox

Question 48

When two similar species inhabit the same area, they may evolve over time to become more different and

A)drive the other species to extinction.
B)reduce direct competition.
C)use up the other species' resources.
D)reduce their genetic variation.

Question 49

Organisms that eat producers are known as

A)cannibals.
B)secondary producers.
C)primary consumers.
D)predators.

Question 50

The figure below shows that the cohabitating ground finches on Pinta Island (topmost graph)experienced character displacement, with birds specializing in either smaller seeds or larger seeds.
Predict the outcome of this cohabitation if large and small seeds had not been initially available.

A)The two species would have been in direct competition and one would become extinct on the island.
B)It would proceed exactly as illustrated except that the range of beak sizes would be less varied.
C)Coevolution would have caused the native plants to produce the necessary variety of seed sizes.
D)The less competitive species would have shifted its feeding preference to insects.

Question 51

Into which category would a human be assigned when eating chicken?

A)producers
B)primary consumers
C)secondary consumers
D)tertiary consumers

Question 52

Which of the following statements about communities is true?

A)They usually have few species of organisms.
B)There can be complex interactions between the organisms that make up a community.
C)They are more abundant in temperate areas.
D)They are made up of mammal species only.

Question 53

Which of the following organisms is not a producer?

A)plankton
B)cow
C)algae
D)oak tree

Question 54

In a typical prairie food web, energy moves from grass to grasshopper to field mouse to fox. Which organism is the primary producer?

A)the grass
B)the grasshopper
C)the mouse
D)the fox

Question 55

As the figure below illustrates, the distribution of numerous intertidal organisms is restricted to bands or zones. The upper limit to the zone is determined by tolerance to physical factors like desiccation, whereas the lower boundary is determined by a biological interaction such as competition.
What could account for the lower limit for Semibalanus?

A)competition from adult Chthamalus living in deeper water
B)the force of the waves on the lower portions of the rock
C)predation from less tolerant predators like sea stars
D)overheating during low tide exposure

Question 56

Certain species of squirrels and acorn woodpeckers both eat acorns. In forests without squirrels, the density of acorn woodpeckers averages 100 per square kilometer, whereas in forests with squirrels the density of acorn woodpeckers is roughly halved. This reduced density most probably results from

A)interference competition.
B)herbivory.
C)character displacement.
D)exploitative competition.

Question 57

In a typical prairie food web energy moves from grass to grasshopper to field mouse to fox. Which organism is the tertiary consumer?

A)the grass
B)the grasshopper
C)the mouse
D)the fox

Question 58

The release of a parasitic wasp in California helped control the infestation of scale insects on citrus trees. However, it also caused the near-extinction of a different species of parasitic wasp. Should we consider this experiment an unqualified success?

A)Yes; the scale insects are controlled, and the extinct wasp was not ecologically important.
B)Yes; as long as we get a result that helps humans, it does not matter what the effect is on other species.
C)No; the effect of the loss of the original species of wasp cannot be predicted and may be more significant than the benefits to the citrus tree crop.
D)No; the citrus tree population in California will now be able to rise to unmanageable numbers.

Question 59

A deer and a caterpillar are peacefully munching on the leaves of the same apple tree. This is an example of

A)pollinator mutualism.
B)behavioral mutualism.
C)symbiosis.
D)competition.

Question 60

Into which category would a human be assigned when eating pepperoni pizza?

A)producers and primary consumers
B)primary and secondary consumers
C)secondary and tertiary consumers
D)producers and primary consumers

Question 61

All of the following except the _____ could be part of the same food chain.

A)clover
B)squirrel
C)rabbit
D)fox

Question 62

The figure below illustrates how, although pines first established themselves as the dominant tree in the Lake Michigan sand dune community, black oaks ultimately become the dominant species.
What best explains the gradual reduction of the pine?

A)Oaks trap sand, causing the dune to level out; pines can only survive in the low, protected areas between the dunes.
B)Pine needles and the shade from existing pines improve the soil composition and moisture, allowing oaks to become established and preventing new pines from surviving.
C)Pines replace the grasses but this destabilizes the dune and increases the amount of moving sand; the loss of pines is not related to the presence of the oaks.
D)Actually oak seeds were always present in the sand; they simply require more time to germinate.

Question 63

Food webs, like the one in the figure below, help biologists predict the impact to a community that changes in species abundance might produce.
After studying the food web above, select a reasonable outcome following the complete disappearance of leopard seals.

A)Killer whales may decline because they eat leopard seals.
B)Chilean seas bass may increase because one of their primary predators is gone.
C)Baleen whales will increase as more krill becomes available.
D)Sperm whales may decline as squid become less abundant.

Question 64

Which of the following experiments would help to identify a keystone species?

A)Introduce more of the suspected species into the area and observe the effects on other community members.
B)Remove the suspected species from the area and observe the effects on other community members.
C)Introduce an invasive species related to the suspected species into the area and observe the effects on the suspected species.
D)Introduce additional individuals of the suspected species' food source into the area and observe the effects on community members.

Question 65

The process that establishes new communities and restores disturbed communities is termed

A)secondary growth.
B)eutrophication.
C)diversification.
D)succession.

Question 66

Which of the following could represent the linear flow of energy within a food web?

A)wolves, lions, and cheetahs
B)grass, bushes, and trees
C)lettuce, rabbits, and foxes
D)sheep, cows, and horses

Question 67

Why would a food web rather than a food chain be the preferred way to represent the movement of food through the community?

A)Food chains are oversimplified and suggest that a consumer eats only a single food item.
B)Food webs place producers at the bottom, whereas food chains place them at the top.
C)Food webs are based on a foundation of producers.
D)Actually, ecologists prefer to use food chains to describe food movements.

Question 68

Communities change with respect to several timescales; an example of long-term change would be the

A)annual variability in population size.
B)presence or absence of a migrant species.
C)species composition of the community.
D)decline in prey abundance during a harsh winter.

Question 69

Which of the following best characterizes humans' method of obtaining energy?

A)primary consumers only
B)secondary consumers only
C)primary, secondary, and occasionally tertiary consumers
D)secondary producers

Question 70

Which of the following can occur when the climate of an area changes?

A)Natural selection usually causes the community to adapt and survive the change with little visible effect.
B)That area becomes uninhabitable to all species and is abandoned.
C)That community may relocate to an area with a climate similar to that of the original location.
D)Continental drift restores communities to climates similar to those from which the communities came.

Question 71

Once a climax community develops, is it likely to remain that way indefinitely?

A)No; over long-term timescales climate change will probably occur, causing the community to eventually change.
B)No; once a climax community develops, the lack of biotic variability eventually degrades the habitat.
C)Yes; once a climax community develops, it will always remain undisturbed
D)Yes; climax communities become so stable that they prevent disturbances from occurring.

Question 72

The removal of a keystone species from a community usually results in

A)the death of all other community members.
B)the disappearance of that community.
C)substantial changes in the abundance of many species.
D)minor changes, if any.

Question 73

During _____ a newly created habitat is inhabited.

A)primary succession
B)climax community formation
C)disturbance colonization
D)keystone recovery

Question 74

A farmer and his family raise 100 acres of corn, 12 chickens, and 2 cows. What is the keystone species?

A)corn
B)chickens
C)cows
D)people

Question 75

All of the following disturbances except _____ would be considered natural.

A)fire
B)flood
C)windstorm
D)mining

Question 76

Which of the following choices best explains, from an ecological perspective, why there are laws that require a wildlife survey before certain building or other land-use projects may proceed?

A)If a keystone species is found, it can be moved to another area where it will establish a new community of organisms.
B)If the only local habitat for a keystone species is disturbed, the entire community of populations will be affected.
C)If the species are surveyed before the land is used, they will all be more likely to survive the building project.
D)If the species are surveyed before the land is used, they will all be more easily distributed to other habitats.

Question 77

The climate of a given location can change over time for two reasons: global climate change and

A)continental drift.
B)agricultural activities.
C)change in the makeup of the local communities.
D)the effect of introduced species.

Question 78

The sea star Pisaster ochraceus was removed from selected intertidal communities along the Washington coast. After 10 years how did those communities compare to control communities?

A)The communities were statistically indistinguishable from one another.
B)Without sea stars, mussels became abundant and crowded out other community members.
C)Other predatory sea stars replaced Pisaster.
D)The mussel populations declined, but most species were unaffected.

Question 79

Why is the existence of food webs important even though food chains also exist?

A)Food webs address the activities of consumers, whereas food chains address the activities of producers.
B)Food chains describe all aspects of interactions within a community, whereas food webs tell us what organisms eat and which are eaten by other organisms.
C)Food webs are smaller groupings than food chains. Food chains allow us to look at the overall picture, whereas food webs provide specific directional information.
D)Food webs tie together many more organisms than a food chain does. If one organism in a food chain disappears, a food web may allow the organisms in the chain to survive based on their interactions with other organisms.

Question 80

In which of the following situations would secondary rather than primary succession be most likely to occur?

A)on an island that has just risen out of the ocean
B)on bare ground exposed by the retreat of a glacier
C)on the surface of recently cooled lava
D)in a forest that had burned to bare ground