Deck 17: Communities of Organisms

Question 1

Which of the following best explains why a grass species might disappear when a meat-eating species is removed from a community?

A)The meat-eating species protects grass directly as a way to provide cover for themselves while stalking their prey.
B)The grass seeds are dispersed by meat eaters who travel long distances and deposit grass seeds in their feces.
C)The meat-eating species eats organisms that eat grass. Removing the meat-eater allows an increase in the abundance of grass-eating organisms.
D)The loss of meat-eaters from a community typically causes drastic changes in the physical environment that prevent grasses from sprouting.

Answer 1

C

Question 2

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

Answer 2

C

Question 3

A measurement of how common one species is compared to another species is referred to as

A)an ecological community.
B)species richness.
C)relative species abundance.
D)keystone species.

Answer 3

C

Question 4

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 5

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 6

A species of bat is removed from a community when it is hunted to extinction. Within two years scientists notice seeds from several plants are no longer germinating. The bat was a

A)community defining species.
B)keystone species.
C)primary consumer.
D)producer.

Question 7

How do ecological communities change over time?

A)Interactions between and among species may cause changes in ecological communities over time.
B)Keystone species typically become the most common species within an ecological community.
C)Species richness typically declines as one species outcompetes all other species.
D)Ecological communities are defined at a given point in time; any change leads to re-classification of the community.

Question 8

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 9

Which of the following would probably NOT occur if a single species was removed from an ecological community?

A)The species richness would change.
B)The relative species abundance would change.
C)The diversity of the community would change.
D)The community would cease to exist.

Question 10

In comparing the two communities shown,

A)community A has a higher relative species abundance.
B)community B has a higher relative species abundance.
C)community A has more primary producers than community B.
D)community B has more primary producers than community A.

Question 11

In comparing the two communities shown,

A)community A has a higher species richness.
B)community B has a higher species richness.
C)community A has more primary producers than community B.
D)community B has more primary producers than community A.

Question 12

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 13

If a disease quickly spreads through a desert and kills moths that are the sole pollinators of long-lived yucca plants, the most likely outcome would be

A)another pollinator would quickly take over and begin to pollinate the yucca plants.
B)the yucca plants would self-pollinate.
C)the yucca plants would die the season after the last yucca moth died.
D)the yucca plants would not be pollinated and would eventually go extinct.

Question 14

Which of the following communities would be considered to have the greatest species richness?

A)An elk gut with 240 species of microorganisms where 95 percent of the microorganisms are bacteria.
B)A small forest in North America made up of 10 species of birds, 125 insect species, and five tree species.
C)A community of 150 small invertebrates classified as 15 different species living within a puddle.
D)A large grassland community in South America with 175 species of grasses, birds, and insects.

Question 15

The sea star Pisaster ochraceus is a keystone species. Ten years after P. ochraceus is removed from selected intertidal communities along the Washington coast, how might those communities compare to control communities?

A)The communities would be statistically indistinguishable from one another.
B)Sea star prey, such as mussels might increase in abundance and crowd out other community members.
C)Other predators will simply replace P. ochraceus and take advantage of prey that P. ochraceus consumed.
D)Prey species, such as mussels would decline, but most species within the community would be unaffected.

Question 16

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 17

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 18

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 19

Which of the following statements accurately describes an ecological community?

A)Communities have clearly fixed boundaries and are always defined on the same scale.
B)Communities can be nested within a larger one.
C)Communities are defined as groups of four or more species within a given area.
D)Communities are groups of species that do not fluctuate over time.

Question 20

The total number of different species living within a community is referred to as

A)an ecological community.
B)species richness.
C)relative species abundance.
D)keystone species.

Question 21

Which of the following statements is FALSE?

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

Question 22

The photograph shown depicts two brightly colored butterfly species, the monarch on the right and its mimic, the viceroy, on the left. The mimicry by the viceroy allows it to

A)exploit food resources otherwise available only to monarchs.
B)find mates among available monarchs.
C)avoid predation because the monarch will make the birds vomit.
D)find locations for laying eggs that are only available to monarchs.

Question 23

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

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

Question 24

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 25

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 songbirds 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 26

Which of the following symbols represents a mutualistic relationship?

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

Question 27

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)pathological
C)competitive
D)mutualistic

Question 28

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

Question 29

All of the following disturbances EXCEPT ________ would be considered natural.

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

Question 30

Undisturbed communities with species compositions that remain stable over time are referred to as

A)climax communities.
B)primary successors.
C)secondary successors.
D)keystone communities.

Question 31

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 32

After studying the food web shown, select a reasonable outcome following the complete disappearance of wolves.

A)Coyotes may decline because they eat wolves.
B)Coyotes may increase because one of their primary predators is gone.
C)Grass, willow, and berries will increase as more elk become available.
D)Voles may decline as coyotes become less abundant.

Question 33

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

A)Prey selectively breed in order to increase the frequency of protective traits in their population.
B)Prey undergo population explosions that allow them to outnumber their predators and thus develop new protective features.
C)Prey organisms mate with other species in order to acquire new protective traits.
D)Natural selection acts on genetic variability already present in the prey population.

Question 34

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

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

Question 35

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 36

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)Both the parasite and the host are harmed.
D)Only the host benefits; the parasite is harmed.

Question 37

During ________ a newly created habitat is inhabited.

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

Question 38

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 39

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)competitive
C)mutualistic
D)pathogenic

Question 40

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

A)commensalism.
B)consumer interaction.
C)competitive limitation.
D)mutualism.

Question 41

Follicle mites live in the hair follicles of human skin. They feed on single cells but do little if any harm to the human; the mite has a stable place to live and reproduce. This is an example of ________.

Question 42

The ________ of a community has two components: the number of different species that live in the community, and the relative abundances of those species.

Question 43

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

Question 44

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 45

________ consumers feed on primary consumers as part or all of their diet.

Question 46

One of the factors governing diversity within a community is species ________, which is defined as the total number of different species living within that community.

Question 47

An ecological ________ is an association of populations of different species that live in the same area.

Question 48

Which of the following is a true statement?

A)Primary succession occurs after disturbances, such as forest fires.
B)Secondary succession only occurs after human intervention.
C)Primary succession tends to take a longer period of time than secondary succession.
D)It typically takes 25 years or less for a climax community to develop after a disturbance.

Question 49

How does primary succession differ from secondary succession?

Question 50

A(n) ________ may begin when a new habitat is formed, such as when rock and soil are deposited by a retreating glacier.

Question 51

A "keystone" is defined in masonry as the stone at the top of an arch that holds the arch together. Using this definition and your knowledge of keystone species, explain how the role of a keystone species within an ecological community is analogous to the keystone within an arch.

Question 52

In which of the following situations would you expect succession to take the longest?

A)A volcanic island forms far from any mainland.
B)A forest fire burns 1,200 acres in Texas.
C)Sand dunes form a new island within a half mile of a mainland.
D)Humans log an area and then burn remaining undergrowth.

Question 53

The figure shown 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 54

The general process by which species in a community are replaced over time is called ________.

Question 55

Define the two key pieces of information used to examine diversity within a community.

Question 56

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 57

Compare and contrast exploitative and interference competition.

Question 58

A(n) ________ is a single sequence of who eats whom in a community.

Question 59

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 60

A community whose species are NOT replaced by other species is classified as a ________ community.

Question 61

Match each term to a statement listed below.
a.mutualism
b.commensalism
c.exploitation
d.competition
a fish that consumes parasites found on a shark

Question 62

Match each term to a statement listed below.
a.mutualism
b.commensalism
c.exploitation
d.competition
a bird building a nest within a tree

Question 63

Match each term to a statement listed below.
a.mutualism
b.commensalism
c.exploitation
d.competition
an elk eating an aspen sapling

Question 64

Match each term to a statement listed below.
a.mutualism
b.commensalism
c.exploitation
d.competition
bears and wolves both consuming carcasses within the same area