Question 1

The number of trophic levels in communities is limited by

Accepted Answer

A)  predation. 
B)  succession. 
C)  competitive exclusion. 
D)  the presence of decomposers. 
E)  the loss of energy between trophic levels.

Question 2

What is one hypothesis biologists have proposed to explain latitudinal gradients in species richness?

Accepted Answer

A)  Intense predation in polar regions limits the number of species. 
B)  Lack of pathogenic organisms in the tropics promotes species richness. 
C)  Lack of mutualistic interactions at higher latitudes limits the number of species. 
D)  Presence of extensive mountain ranges and coastlines at higher latitudes limits species richness. 
E)  Greater energy flow in the tropics has led to narrower,more specialized niches and thus promoted species diversity.

Question 3

Edith's checkerspot butterfly,found on rock outcrops near San Francisco,depends on plants that only grow on soils containing high concentrations of certain heavy metals,called _______ soils.

Accepted Answer

The answer of Edith's checkerspot butterfly,found on rock outcrops near...

Question 4

Refer to the table below.Fauna groups A-D are populating an island.They have the dispersal abilities shown,and they are either strongly affected or little affected by similar species already present on the island.If strongly affected,their extinction rate rises;if not strongly affected,extinction rate does not change.Which group of fauna would most likely maintain the largest number of species on the island,assuming all other factors are equal?

Accepted Answer

A)  Fauna group A 
B)  Fauna group B 
C)  Fauna group C 
D)  Fauna group D 
E)  All fauna groups equally

Question 5

Why is it important to place a value on ecosystem services?

Accepted Answer

A)  To enable cities and businesses to charge for them 
B)  To insure that they are delivered to those who need them 
C)  To insure that their value is recognized and they are protected 
D)  To make it easier to transform them into technological services 
E)  To insure that they are used only for human,not natural,purposes

Question 6

Between 1950 and 1985,half of Central America's tropical forests were cut,and the remainder was scattered in small isolated fragments.Another 19 percent of the forest had disappeared by 2005.A survey of the remaining tropical forest areas would most likely show

Accepted Answer

A)  increased species richness. 
B)  decreased species richness. 
C)  decreased extinction rates. 
D)  increased colonization rates. 
E)  increased primary productivity.

Question 7

A study of arthropod species on a series of mangrove islands shows that two years after all arthropods were removed,the number of species on each island has returned to approximately its original number.However,the numbers are not constant-they vary from month to month as new censuses are taken.Explain why this might occur.

Accepted Answer

The answer of A study of arthropod species on a...

Question 8

According to the island biogeography model,which two factors primarily determine the number of species on an island?

Accepted Answer

A)  Climate and size of island 
B)  Species pool and speciation rate 
C)  Speciation rate and extinction rate 
D)  Species evenness and habitat structure 
E)  Size of island and distance from mainland

Question 9

Cows,which eat grass and other plant materials,belong to the _______ trophic level.

Accepted Answer

The answer of Cows,which eat grass and other plant materials,belong...

Question 10

Ecosystem services provided by a natural community are likely to be of higher quality if the natural community has _______ species diversity.

Accepted Answer

The answer of Ecosystem services provided by a natural community...

Question 11

Which of the following would not be considered an example of an ecosystem good or service?

Accepted Answer

A)  Forests removing excess carbon dioxide from the atmosphere 
B)  Bees pollinating an invasive weed species 
C)  Bacteria metabolizing a substance that poses a health threat to humans or cattle 
D)  Blowflies limiting the population growth of an insect pest species 
E)  Marsh grasses limiting the effects of storm surges from hurricanes

Question 12

What is the most likely reason that the curve in the top graph mostly levels off between five and ten species?

Accepted Answer

A)  The prairie community only has five to ten niches. 
B)  The community is approaching its maximum productivity,given the resources available. 
C)  With more than 10 species,competition prevents further productivity. 
D)  With more than 10 species,species diversity no longer influences productivity. 
E)  The additional species must be smaller and therefore contribute less to the biomass.

Question 13

Introduction of new dung beetle species into Australia eventually resulted in a species composition that enabled decomposition of built-up dung,improved soil quality and net primary productivity,and made cattle healthier.This series of events illustrates the value of

Accepted Answer

A)  extinctions. 
B)  ecosystem services. 
C)  ecological succession. 
D)  ecological transitions. 
E)  the theory of island biogeography.

Question 14

A scientist measuring the amount of energy per unit time that moves between a community and its abiotic environment is measuring the community's energy _______.

Accepted Answer

The answer of A scientist measuring the amount of energy...

Question 15

In determining sizes of habitat patches,corridors,and other conservation techniques,ecologists should develop their plans around key species (such as wolves in Yellowstone National Park),whose removal from ecosystems may cause a(n)_______.

Accepted Answer

The answer of In determining sizes of habitat patches,corridors,and other...

Question 16

A forensic entomologist can date an organism's time of death according to the species of insects found on or near the body.This scientist is applying knowledge about the process of

Accepted Answer

A)  extinction. 
B)  succession. 
C)  trophic cascades. 
D)  island biogeography. 
E)  community structure.

Question 17

An island begins to recolonize after a volcanic eruption.In the first year of recolonization,20 new species become established.In the second year,10 new species become established,and in the third year,5 species become established.The decrease in number of colonizing species over time most likely occurs because by years 2 and 3

Accepted Answer

A)  more arrivals represent already established species. 
B)  fewer species from the mainland are available to colonize. 
C)  fewer species remain that are adapted to island conditions. 
D)  competition and predation are preventing new species from colonizing. 
E)  population growth has overwhelmed the island,leaving no space for new species.

Question 18

A common way to measure community function is to measure

Accepted Answer

A)  metabolism of selected species in the community. 
B)  metabolism of selected individuals in the community. 
C)  total amount of biomass at the end of the growing season. 
D)  total biomass of major species at the end of the growing season. 
E)  flux,or flow rate of energy between community and environment.

Question 19

Refer to the diagram below.Briefly explain the similarities and differences in species diversity among communities A,B,and C,taking into account both species richness and species evenness.

Accepted Answer

The answer of Refer to the diagram below.Briefly explain the...

Question 20

Species composition,species number,and species abundance together constitute the major components of _______.

Accepted Answer

The answer of Species composition,species number,and species abundance together constitute...

Exam 44: Ecological Communities