Question 1

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, it provides more food options and resources. This leads to an increase in the number of species occupying different niches, which ultimately leads to an increase in the number of predators in the food web. Therefore, the proportion of predators in the web tends to increase.

Question 2

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 exist in both terrestrial and aquatic systems. They are defined as species that have an outsized impact on the ecosystem compared to their abundance, and this can occur in any type of ecosystem.

Question 3

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

D

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 that has a disproportionately large effect on the structure and function of the community, even though it may not be the most abundant or dominant species. Their presence or absence can greatly affect the abundance and diversity of other species in the community, and they often play a crucial role in maintaining ecosystem stability and resilience. Keystone species can be predators, herbivores, or even plants, and their removal can lead to cascading effects throughout the food web.

Question 5

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

When the 95% confidence intervals for the two means do not overlap, it indicates that there is a statistically significant difference between the means. This is because there is only a 5% chance that the true population means are the same and the difference observed in the sample is due to chance. Therefore, we can reject the null hypothesis of equal means and infer a significant difference.

Question 6

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

Robert Paine's study focused on the intertidal community, where space is the most important limiting resource. This is because the intertidal zone is a narrow strip between the high tide and low tide lines, which means that there is limited space for organisms to live and compete for resources. Light, plankton, nitrogen, and water are also important resources, but they are not as limiting as space in this particular ecosystem.

Question 7

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 8

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 9

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 10

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 important effects on community structure of the South African fynbos, as it may affect the distribution and abundance of plant species.

Question 11

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

Studies have shown that human hunters in the Amazon rain forests primarily target the largest mammal and bird species, such as tapirs, deer, and large primates. This is because these animals provide the most meat and are therefore the most efficient use of hunting efforts. As a result, their populations have been greatly reduced.

Question 12

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 provide the service of cleaning other fish of their externally-feeding parasites, such as lice and mites. This helps to maintain the health and well-being of the other fish, while also benefiting the cleaner wrasse by providing them with a source of nutrition.

Question 13

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 14

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

Robert Paine's studies showed that the removal of the starfish Pisaster led to a major change in the intertidal community, with an increase in the number of mussels and a decrease in the diversity of other species. This indicates that the starfish is a keystone species in the Washington intertidal community.

Question 15

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 16

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 divided into four major trophic levels: plant, herbivore, parasite, and carnivore.

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

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 19

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 20

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...

Quiz 17: Species Interactions and Community Structure

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

Keystone species

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

A keystone species is one

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

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

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

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

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

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

Human hunters in the Amazon rain forests kill

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

Weaver ants provide effective protection of citrus trees because they

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

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

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?

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

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?

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

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