Question 1

Teja Tscharntke simplified the food web associated with the wetland reed Phragmites australis by dividing the species into which of the following major trophic levels?
A)plant,herbivore,piscivore,granivore
B)herbivore,carnivore,detritivore,consumer
C)herbivore,parasite,carnivore,detritivore
D)plant,herbivore,parasite,carnivore
E)plant,detritivore,parasite,herbivore

Accepted Answer

The wetland reed Phragmites australis is the plant species that is being simplified into trophic levels. Therefore, the first trophic level is plant. The next level would be herbivores that feed on the plant, followed by carnivores that feed on the herbivores. Parasites and detritivores are not mentioned in the context of this simplified food web, so they are not relevant. Therefore, the best choice is D, which includes plant, herbivore, parasite, and carnivore trophic levels.

Question 2

In Jane Lubchenco's tidepool system,removal of the herbivorous snail Littorina led to
A)dominance of the tidepools by the unpalatable alga Chondrus.
B)replacement of Chondrus by the more palatable alga Enteromorpha.
C)replacement of Chondrus by other algae better adapted to herbivory.
D)replacement of Enteromorpha by other algae that are better competitors.
E)no marked change in the algal community.

Accepted Answer

When the herbivorous snail Littorina was removed from Jane Lubchenco's tidepool system, the more palatable alga Enteromorpha replaced the unpalatable alga Chondrus. This is because Littorina normally feeds on Enteromorpha, keeping its population in check. Without Littorina, Enteromorpha was able to outcompete Chondrus.

Question 3

Cleaner wrasse are mutualists of other coral reef fishes.What benefit do they provide to those other fish?
A)They suppress diseases because they consume carcasses of dead fish.
B)They keep water oxygenated because they consume organic debris before it can rot.
C)They keep fish relatively free of externally-feeding parasites.
D)They maintain fish habitat by keeping corals free of encrusting algae.
E)They reduce fish mortality by repelling large vertebrate predators.

Accepted Answer

Cleaner wrasse are known to remove parasites, dead skin, and mucus from other fish, which improves their health and reduces the prevalence of externally-feeding parasites.

Question 4

A keystone species is one
A)that makes up a very large proportion of total community biomass.
B)that feeds on a very large fraction of all available prey species.
C)that is fed on by a very large fraction of all predators in its community.
D)whose feeding activities have a disproportionate effect on the structure of its community.
E)that occupies the lowest level (the base)of the food web.

Accepted Answer

A keystone species is one whose presence and activities have a disproportionate effect on the structure and functioning of its community. This can be through its role in controlling the densities of other species or its influence on the physical environment. Keystone species are often relatively rare or low in biomass, but their impact is crucial to the stability and diversity of the ecosystem.

Question 5

Teja Tscharntke's studies of the food web associated with Phragmites reeds revealed that
A)only a single parasitoid species can persist exploiting a single species of herbivore.
B)only a single herbivore species can persist attacking a single species of plant.
C)predation by birds actually protects herbivores,because the birds feed on parasitoid-infested herbivore galls but not uninfested galls.
D)within local food webs,all interactions tend to be of roughly the same strength.
E)recognizing variation in interaction strength can greatly simplify the depiction of a food web.

Accepted Answer

The answer of Teja Tscharntke's studies of the food web...

Question 6

The use of predaceous weaver ants to control pest insects in citrus orchards was first recorded in A)California in the 1950s. B)Florida in the 1920s. C)Mexico in Mayan times. D)China in the 17^th century. E)China in the 4^th century.

Accepted Answer

The answer of The use of predaceous weaver ants to...

Question 7

In Robert Paine's studies of the Washington intertidal community,which organism proved to be a keystone species?
A)the whelk Thais
B)acorn barnacles
C)chitons
D)the starfish Pisaster
E)limpets

Accepted Answer

In Robert Paine's studies, the starfish Pisaster proved to be a keystone species as its removal significantly altered the intertidal community, leading to an increase in the population of mussels, which in turn out-competed other species and decreased overall species diversity.

Question 8

In the Washington intertidal community studied by Robert Paine,the most important limiting resource is
A)space.
B)light.
C)plankton.
D)nitrogen.
E)water.

Accepted Answer

In the Washington intertidal community studied by Robert Paine, the most important limiting resource was space. Paine demonstrated this by removing the top predator, the sea star, from the community, which resulted in a dramatic increase in the number of mussels, the primary space occupiers in the community. This showed that the sea star was limiting the amount of space available for other species by controlling the mussel population.

Question 9

Martinsen,Driebe,and Whitham provided evidence for _______________________ with beaver consumption of cottonwoods resulting in higher densities of herbivorous beetles.
A)indirect keystone predation
B)indirect commensalism
C)apparent competition
D)keystone predation
E)indirect competition

Accepted Answer

The answer of Martinsen,Driebe,and Whitham provided evidence for _______________________ with...

Question 10

Weaver ants provide effective protection of citrus trees because they
A)remove harmful soft-scale insects (mealybugs).
B)remove all plant-feeding insects.
C)cultivate soft-scale insects,but do not allow them to feed on the trees.
D)cultivate soft-scale insects,but still allow them to be attacked by parasitoids and predators.
E)None of the choices are correct.

Accepted Answer

The answer of Weaver ants provide effective protection of citrus...

Question 11

In zooplankton and intertidal communities,as the overall diversity of the food web increases,the proportion of predators in the web
A)tends to decrease.
B)tends to increase.
C)first decreases,then increases again.
D)first increases,then decreases again.
E)stays about the same.

Accepted Answer

As the overall diversity of the food web increases, the proportion of predators tends to increase because a more diverse food web supports a greater variety of prey species, which in turn can support a larger and more diverse predator population.

Question 12

We can infer a statistically significant difference between two population means when
A)our estimates of the two means are different.
B)the variances of the two means do not overlap.
C)the standard deviations of the two means do not overlap.
D)the 95% confidence intervals for the two means do not overlap.
E)the 95% confidence intervals for the two means are of different widths.

Accepted Answer

To infer a statistically significant difference between two population means, we need to compare the confidence intervals for the two means. If the confidence intervals do not overlap, it indicates that the difference in means is statistically significant. Therefore, the correct answer is D, which states that the 95% confidence intervals for the two means do not overlap.

Question 13

Which is the correct order of prey consumption in the Antarctic pelagic food web?
A)Krill$\rightarrow$Diatoms$\rightarrow$Ross seal$\rightarrow$Crabeater seal$\rightarrow$Killer Whale
B)Diatoms$\rightarrow$Krill$\rightarrow$Ross seal$\rightarrow$Crabeater seal$\rightarrow$Killer Whale
C)Diatoms$\rightarrow$Squid$\rightarrow$Emperor penguin$\rightarrow$Leopard seal$\rightarrow$Killer whale
D)Krill$\rightarrow$Squid$\rightarrow$Weddell seal$\rightarrow$Leopard Seal$\rightarrow$Killer whale
E)Diatoms$\rightarrow$Squid$\rightarrow$Krill$\rightarrow$Emperor penguin$\rightarrow$Leopard seal

Accepted Answer

The answer of Which is the correct order of prey...

Question 14

Based on studies by Jane Lubchenco,what influence does the population density of the herbivorous intertidal snail,Littorina littorea,have on the number of algal species?
A)as snail density increases from low to medium,the number of algal species increases
B)as snail density increases from medium to high,the number of algal species increases
C)as snail density increases from low to medium,the number of algal species decreases
D)as snail density increases from medium to high,the number of algal species decreases
E)both as snail density increases from low to medium,the number of algal species increases and as snail density increases from medium to high,the number of algal species decreases

Accepted Answer

The answer of Based on studies by Jane Lubchenco,what influence...

Question 15

A Predator and its prey interact __________,but if the predator affects another species through this interaction,ecologists describe it as a(n)___________ interaction.
A)strongly; inefficient
B)directly; variable
C)weakly; diffuse
D)indirectly; keystone
E)directly; indirect

Accepted Answer

The answer of A Predator and its prey interact __________,but...

Question 16

Which statement best sums up the relationship between density of the herbivorous snail Littorina and the diversity of algae in its habitat?
A)highest diversity when Littorina are abundant,in all habitats
B)highest diversity when Littorina are rare,in all habitats
C)highest diversity when Littorina densities are intermediate,in all habitats
D)highest diversity in tidepools when Littorina are rare,but in emergent habitats when Littorina densities are intermediate
E)highest diversity in tidepools when Littorina densities are intermediate,but in tidepools when Littorina are rare

Accepted Answer

The answer of Which statement best sums up the relationship...

Question 17

Kirk Winemiller,who described the feeding relations among freshwater fish in Venezuela and Costa Rica,simplified the food webs from his study sites by presenting common-fish webs.Common-fish webs
A)exclude rare species.
B)both exclude rare species and include the fish species whose aggregate abundance comprise 95% of the individuals collected.
C)exclude species that do not comprise at least 30% of the community.
D)include the fish species whose aggregate abundance comprise 95% of the individuals collected.
E)exclude species that do not comprise at least 40% of the community.

Accepted Answer

Kirk Winemiller's approach to simplifying food webs into common-fish webs involves both excluding rare species and including those fish species whose aggregate abundance comprises 95% of the individuals collected. This method allows for a more manageable and representative analysis of the feeding relationships among the most common fish in the ecosystem.

Question 18

Keystone species
A)appear to be common in terrestrial systems,but not in aquatic ones.
B)appear to be common in both terrestrial and aquatic systems.
C)appear to be common in aquatic systems,but not in terrestrial ones.
D)by definition,cannot occur in aquatic systems.
E)by definition,cannot occur in terrestrial systems.

Accepted Answer

Keystone species can occur in both terrestrial and aquatic systems. A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance. Examples of keystone species include wolves in Yellowstone National Park (terrestrial) and sea otters in kelp forests (aquatic).

Question 19

Human hunters in the Amazon rain forests kill
A)large numbers of almost every mammal and bird species,for food and for skins.
B)large numbers of the smallest mammal and bird species,which are easiest to catch.
C)large numbers primarily of the largest mammal and bird species.
D)large numbers of mammals and birds,but do not greatly affect population densities.
E)only a few mammals and birds,but because humans are keystone species,these few kills greatly reduce population densities.

Accepted Answer

Human hunters in the Amazon rain forests kill large numbers primarily of the largest mammal and bird species. This is because these species are usually preferred for their meat and therefore are more valuable to hunters. The hunting of these larger species can significantly affect their population densities, as they have lower reproductive rates and longer lifespans compared to smaller species.

Question 20

Invasive Argentine ants have an important effect on community structure of the South African fynbos because
A)they do not disperse seeds,while native ants do.
B)they disperse seeds more effectively than do native ants.
C)they disperse seeds in different spatial patterns than do native ants.
D)as keystone species,they greatly increase the local diversity of native ants.
E)Argentine ants have invaded many communities,but not the South African fynbos.

Accepted Answer

Invasive Argentine ants do not disperse seeds, while native ants do. This has an important effect on the community structure of the South African fynbos because seed dispersal is a crucial process in maintaining plant diversity and ecosystem functioning. Without native ants and other seed dispersers, the fynbos may experience a decline in plant diversity and a shift in community composition.

Quiz 17: Species Interactions and Community Structure

Teja Tscharntke simplified the food web associated with the wetland reed Phragmites australis by dividing the species into which of the following major trophic levels?

In Jane Lubchenco's tidepool system,removal of the herbivorous snail Littorina led to

Cleaner wrasse are mutualists of other coral reef fishes.What benefit do they provide to those other fish?

A keystone species is one

Teja Tscharntke's studies of the food web associated with Phragmites reeds revealed that

The use of predaceous weaver ants to control pest insects in citrus orchards was first recorded in

In Robert Paine's studies of the Washington intertidal community,which organism proved to be a keystone species?

In the Washington intertidal community studied by Robert Paine,the most important limiting resource is

Martinsen,Driebe,and Whitham provided evidence for _______________________ with beaver consumption of cottonwoods resulting in higher densities of herbivorous beetles.

Weaver ants provide effective protection of citrus trees because they

In zooplankton and intertidal communities,as the overall diversity of the food web increases,the proportion of predators in the web

We can infer a statistically significant difference between two population means when

Which is the correct order of prey consumption in the Antarctic pelagic food web?

Based on studies by Jane Lubchenco,what influence does the population density of the herbivorous intertidal snail,Littorina littorea,have on the number of algal species?

A Predator and its prey interact ,but if the predator affects another species through this interaction,ecologists describe it as a(n) _ interaction.

Which statement best sums up the relationship between density of the herbivorous snail Littorina and the diversity of algae in its habitat?

Kirk Winemiller,who described the feeding relations among freshwater fish in Venezuela and Costa Rica,simplified the food webs from his study sites by presenting common-fish webs.Common-fish webs

Keystone species

Human hunters in the Amazon rain forests kill

Invasive Argentine ants have an important effect on community structure of the South African fynbos because