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Life: The Science of Biology, Ninth Edition
Sadava • Hillis • Heller • Berenbaum
Chapter 57: Community Ecology
TEST FILE QUESTIONS
(By Norman Johnson)
Multiple Choice
1. Which of the following statements about cheese skippers is true?
a. Their presence can be used to estimate the time of death of a body.
b. They are among the first species to arrive when a dead body starts decomposing.
c. They prefer hair and nails to flesh.
d. Both a and b
e. Both a and c
Answer: a
Textbook Reference: 57.0 Dead reckoning
Page: 1203
Bloom’s Category: 1. Remembering
2. The species that live and interact in a given area constitute an ecological
a. biome.
b. family.
c. food web.
d. community.
e. trophic level.
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
Bloom’s Category: 1. Remembering
3. Which of the following statements about communities is false?
a. They can vary tremendously in size and scope.
b. An important factor in determining their species richness is the amount of energy
available.
c. Energy enters communities through primary consumers.
d. An ecological community comprises a group of species that coexist and interact within
a defined area.
e. All of the above are true; none is false.
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
Bloom’s Category: 1. Remembering
4. A community ecologist would most likely be concerned with
a. energy flow through an ecosystem.
b. population growth of a single species.
c. interactions among individuals of the same species living together in a small area.
d. interactions among individuals of different species living together in a small area.
e. the cycling of matter through biotic and abiotic components of an area.
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
Bloom’s Category: 2. Understanding
5. Which of the following is a primary producer?
a. Spider
b. Earthworm
c. Oak tree
d. Human
e. None of the above
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
6. Which of the following is a primary consumer?
a. A predatory fish
b. A detritus-eating roundworm
c. An oak tree
d. A herbivorous beetle larva
e. None of the above
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
7. In a food web with energy flowing up, a(n) _______ is one trophic level above a
primary consumer.
a. primary producer
b. decomposer
c. herbivore
d. autotroph
e. secondary consumer
Answer: e
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
8. Organisms that receive their energy from several trophic levels are said to be
a. detritivores.
b. herbivores.
c. primary consumers.
d. secondary consumers.
e. omnivores.
Answer: e
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 1. Remembering
9. Organisms that are _______ acquire their energy from eating primary consumers.
a. primary producers
b. secondary consumers
c. herbivores
d. autotrophs
e. None of the above
Answer: b
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
10. By definition, autotrophs are
a. primary consumers.
b. primary producers.
c. secondary consumers.
d. secondary producers.
e. decomposers.
Answer: b
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
11. If secondary consumers are the highest trophic level in a community, how many
trophic levels are in the community (not counting decomposers)?
a. Two
b. Three
c. Four
d. Three if it is an aquatic community, four if it is a terrestrial community
e. Three if it is a terrestrial community, four if it is an aquatic community
Answer: b
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 3. Applying
12. If gross primary productivity is 120 units per day, and the respiration rate is 30 units
per day, net primary productivity is _______ units per day.
a. 4
b. 30
c. 90
d. 120
e. 150
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 3. Applying
13. Grain is eaten by cows, and cows are eaten by humans. If the ecological transfer
efficiency between each trophic level is 10 percent, how much grain is required to
produce 70 kg of human biomass?
a. 7 kg
b. 70 kg
c. 700 kg
d. 7,000 kg
e. 70,000 kg
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 3. Applying
14. Which of the following factors reduces the efficiency of energy transfer between
trophic levels?
a. Lack of availability of some biomass
b. Heat loss
c. Indigestibility of some biomass
d. All of the above
e. None of the above
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 1. Remembering
15. The number of trophic levels in most communities is limited by
a. the presence of decomposers.
b. predation.
c. competitive exclusion.
d. succession.
e. the loss of energy between trophic levels.
Answer: e
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 1. Remembering
16. In most communities, which of the following is greater in tertiary consumers as
compared to secondary consumers?
a. Reproductive rates
b. Number of species
c. Total biomass
d. Body size
e. None of the above
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 2. Understanding
17. In which of the following communities would one expect to see more biomass in
primary consumers than in primary producers?
a. Forest
b. Grassland
c. Open ocean
d. All of the above
e. None of the above
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1207
Bloom’s Category: 2. Understanding
18. In which of the following communities would one expect to see greater energy flow
into primary consumers than into primary producers?
a. Forest
b. Grassland
c. Open ocean
d. All of the above
e. None of the above
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1207
Bloom’s Category: 2. Understanding
19. Which of the following always has a “pyramidal” shape (i.e., decreasing values at
higher trophic levels)?
a. Pyramids of number
b. Pyramids of biomass
c. Pyramids of energy
d. Both a and b
e. None of the above
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1207
Bloom’s Category: 2. Understanding
20. As productivity increases, species richness in a community
a. generally increases.
b. generally decreases.
c. stays relatively flat.
d. increases at first and then decreases.
e. decreases at first and then increases.
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1207
Bloom’s Category: 2. Understanding
21. For most communities, species richness will _______ if fertilizer is added when
productivity is low, and it will _______ if fertilizer is added when productivity is high.
a. increase; increase
b. increase; decrease
c. remain the same; increase
d. decrease; increase
e. decrease; decrease
Answer: e
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1207
Bloom’s Category: 2. Understanding
22. The introduction of a large predatory fish into a lake will lead to declines in the
populations of smaller fish; this decrease in the smaller fish will lead to an increase in the
plankton on which they feed. This phenomenon is called
a. character displacement.
b. keystone exchange.
c. trophic cascade.
d. primary succession.
e. heterotrophic succession.
Answer: c
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1208
Bloom’s Category: 2. Understanding
23. Which of the following statements about wolves in Yellowstone National Park is
true?
a. They are the only predators of moose and elk.
b. Their disappearance led directly to the severe reduction of young aspen trees.
c. Their disappearance led indirectly to the severe reduction of young aspen trees.
d. Both a and b
e. Both a and c
Answer: c
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1208
Bloom’s Category: 1. Remembering
24. The reintroduction of wolves into Yellowstone in 1995 had _______ effect on aspen
and _______ effect on elk.
a. a direct; a direct
b. a direct; an indirect
c. a direct; no
d. an indirect; a direct
e. an indirect; an indirect
Answer: d
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1208
Bloom’s Category: 2. Understanding
25. Beavers affect communities by
a. what they eat.
b. altering patterns of vegetation as they preferentially cut down certain trees.
c. creating meadows and ponds by means of their dams.
d. All of the above
e. None of the above
Answer: d
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 1. Remembering
26. A species that exerts an influence on a community that is much greater than its
abundance would lead one to expect is called a(n)
a. primary producer.
b. ecosystem engineer.
c. keystone species.
d. successional species.
e. Tilman species.
Answer: c
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 1. Remembering
27. Which of the following resulted from Robert Paine’s removing the predator sea star
from parts of the intertidal zone?
a. Many species disappeared from the environment.
b. The species richness increased.
c. One species of mussel, Mytilus californianus, benefited.
d. Both a and c
e. Both b and c
Answer: d
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 1. Remembering
28. A termite mound alters the environment in such a way that it creates new habitats for
a variety of organisms. In constructing these mounds, therefore, termites can be
considered
a. a keystone species.
b. trophic cascaders.
c. ecosystem engineers.
d. facilitator species.
e. primary producers.
Answer: c
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 2. Understanding
29. Suppose you were going up the west coast of Australia and observed that there are
many species of termites in any one community, and the species composition changed
little between communities. You would conclude that for these termites,
a. both the alpha and beta diversities are high.
b. the alpha diversity is low, but the beta diversity is high.
c. the alpha diversity is high, and the beta diversity is low.
d. the alpha diversity is high, and the beta diversity is negative.
e. the alpha diversity is low, and the beta diversity is negative.
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 5. Evaluating
30. Suppose that the gamma diversity for a marshy habitat and the gamma diversity for a
sandy habitat are comparable for a particular geographic region, but the alpha diversity
for marshy habitats tends to be much greater than the alpha diversity for sandy habitats.
We could conclude that
a. beta diversity is higher in marshy habitats.
b. beta diversity is roughly the same in both marshy and sandy habitats.
c. beta diversity is lower in marshy habitats.
d. the Shannon index is higher in marshy habitats, but Sorenson’s index is lower.
e. the Shannon index is lower in marshy habitats, but Sorenson’s index is higher.
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 5. Evaluating
31. Three species of grasshoppers are found in a transect: 10 of species A, 15 of species
B, and 25 of species C. What is the Shannon diversity index of this transect? (Note: * =
times, and ln (x) is the natural logarithm of x.)
a. [0.1 * ln (0.1)] + [0.15 * ln (0.15)] + [0.25 * ln (0.25)]
b. [10 * ln (10)] + [15 * ln (15)] + [25 * ln (25)]
c. The negative of {[10 * ln (10)] + [15 * ln (15)] + [25 * ln (25)]}
d. The negative of {[0.1 * ln (0.1)] + [0.15 * ln (0.15)] + [0.25 * ln (0.25)]}
e. The negative of {[0.2 * ln (0.2)] + [0.3 * ln (0.3)] + [0.5 * ln (0.5)]}
Answer: e
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 3. Applying
32. In calculating alpha diversity, the Shannon diversity index measures
a. the absolute abundance of species.
b. the relative abundance of species.
c. the ecological diversity of species.
d. the morphological diversity of species.
e. differences in species composition across habitats or communities.
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 2. Understanding
33. Which of the following would be most useful for calculating alpha diversity?
a. Sorenson’s index
b. The Spicoli index
c. The Shannon index
d. The species–area relationship
e. The successional integral
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 1. Remembering
34. In one community, 10 species of grasses are found. A nearby community has 15
species, and shares 6 of those species with the first community. What is Sorenson’s index
for these communities?
a. 0.24
b. 0.4
c. 0.48
d. 0.6
e. 0.8
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211
Bloom’s Category: 3. Applying
35. Sorenson’s index measures _______ diversity.
a. alpha
b. beta
c. functional
d. gamma
e. delta
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211
Bloom’s Category: 1. Remembering
36. A study of diversity patterns in an agricultural area of southern England showed that
rivers have _______ alpha diversity and _______ beta diversity.
a. high; high
b. high; low
c. high; negative
d. low; high
e. low; low
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211
Bloom’s Category: 1. Remembering
37. Which of the following statements about species richness is true?
a. It is highest in the temperate zone in both hemispheres.
b. It is highest in the Northern temperate zone, followed by the tropics, followed by the
Southern temperate zone.
c. It is highest in the tropics.
d. It is highest in the Southern temperate zone, followed by the tropics, followed by the
Northern temperate zone.
e. None of the above
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211
Bloom’s Category: 1. Remembering
38. Which of the following is a hypothesis generated by biologists to explain species
richness gradients?
a. Greater competition in the tropics has led to narrower niches and thus more species in
the tropics than elsewhere.
b. The lack of mutualisms in the higher latitudes limits the number of species in high
latitude communities.
c. Intense predation in the polar regions limits the number of species that can live there.
d. Both a and b
e. Both b and c
Answer: a
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 1. Remembering
39. One assumption of the theory of island biogeography is that _______ population sizes
of species will _______.
a. small; decrease the likelihood of speciation
b. small; increase the likelihood of speciation
c. large; increase the species pool
d. large; decrease the species pool
e. None of the above
Answer: e
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 2. Understanding
40. According to the island biogeography model, _______ and _______ determine the
number of species on an island.
a. climate; vicariant events
b. the size of the island; its distance from the mainland
c. the species pool; the speciation rate
d. the speciation rate; the extinction rate
e. elevation; shape
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 2. Understanding
41. The island biogeography theory addresses
a. the extent of beta diversity in different biogeographic regions.
b. the latitudinal gradient of species richness.
c. species–area relationships.
d. Both a and b
e. Both a and c
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 2. Understanding
42. Which of the following statements about island biogeography is false?
a. Major disturbances can serve as “natural experiments” that allow researchers to
estimate colonization rates.
b. When species numbers are above the equilibrium, island biogeography theory predicts
that extinction rates will increase.
c. When species numbers are far below the equilibrium, island biogeography theory
predicts that immigration rates will increase.
d. The theory of island biogeography is particularly concerned with the identity of species
found at particular islands.
e. All of the above are true; none is false.
Answer: d
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212–1213
Bloom’s Category: 2. Understanding
43. Daniel Simberloff and Edward Wilson tested the island biogeography theory by
a. releasing animals on oceanic islands.
b. defaunating tiny islets of mangroves in the Florida Keys.
c. observing the results of the Krakatau volcano explosion.
d. reconstructing phylogenetic relationships of horses.
e. None of the above
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1213
Bloom’s Category: 1. Remembering
44. Which of the following statements about disturbances is false?
a. They are always caused by biotic factors.
b. They can be beneficial to some species.
c. They can be caused by keystone species.
d. Small disturbances are more common than large ones, but large disturbances have a
greater overall effect.
e. All of the above are true; none is false.
Answer: a
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 1. Remembering
45. The plants that grow best on recently formed moraines at Glacier Bay are those that
a. grow under conditions of low oxygen.
b. are superior competitors.
c. form mutualisms with nitrogen-fixing bacteria.
d. are highly resistant to herbivores.
e. None of the above
Answer: c
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 1. Remembering
46. Which of the following statements about the patterns of succession in moraines at
Glacier Bay is true?
a. We know a great deal about the patterns from detailed observations that have taken
place over the past 200 years.
b. The youngest moraines are populated with bacteria, fungi, and photosynthetic
microorganisms.
c. The composition of the soil has remained relatively constant over the past 200 years.
d. Nitrogen is highly abundant in young moraines.
e. Both a and b
Answer: b
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 1. Remembering
47. Which of the following is the correct chronological order (from youngest to oldest)
for the succession of species in Glacier Park?
a. Alders, spruces, lichens
b. Spruces, alders, lichens
c. Spruces, lichens, alders
d. Lichens, spruces, alders
e. Lichens, alders, spruces
Answer: e
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 1. Remembering
48. Following a severe ice storm in 1991 in Rochester, New York, the composition of the
trees changed as the community recovered from the disturbance. This is an example of
a. competitive succession.
b. primary succession.
c. secondary succession.
d. keystone succession.
e. None of the above
Answer: c
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1215
Bloom’s Category: 1. Remembering
49. Which of the following would most likely be found late in succession?
a. Mostly plants that produce a high number of small seeds
b. Simple food webs
c. Most nutrients present as detritus
d. Plants producing chemicals that interfere with the growth of other plants
e. Mostly plants that are good dispersers
Answer: d
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1215
Bloom’s Category: 2. Understanding
50. Which of the following statements about succession is false?
a. Facilitation plays an important role in succession.
b. Inhibition plays an important role in succession.
c. As succession proceeds, K-strategy plants are replaced by r-strategy plants.
d. Food webs increase in complexity during succession.
e. All of the above are true; none is false.
Answer: c
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1215
Bloom’s Category: 1. Remembering
51. The presence of soil fauna increases the likelihood that many plants will be
established during succession. This is an example of
a. disturbance.
b. facilitation.
c. recruitment.
d. reinforcement.
e. inhibition.
Answer: b
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1216
Bloom’s Category: 2. Understanding
52. In the lodgepole pine community, periodic disturbances occur in the form of
a. floods.
b. fire.
c. beetle infestations.
d. fungal infections.
e. predators.
Answer: b
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1216
Bloom’s Category: 1. Remembering
53. The first phase of decomposition is
a. dry decay.
b. autolysis.
c. primary succession.
d. wet decay.
e. putrefaction.
Answer: b
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1216
Bloom’s Category: 1. Remembering
54. Which of the following represents the correct chronological order (from earliest to
latest) in which the organisms below appear on a dead body?
a. Spider beetles, blowflies, flesh flies
b. Spider beetles, flesh flies, blowflies
c. Blowflies, flesh flies, spider beetles
d. Flesh flies, blowflies, spider beetles
e. Flesh flies, spider beetles, blowflies
Answer: c
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1217
Bloom’s Category: 2. Understanding
55. David Tilman’s experiments showed that as species richness increases, productivity
_______ and the variation in productivity _______.
a. decreases; increases
b. decreases; remains constant
c. decreases; decreases
d. increases; increases
e. increases; decreases
Answer: e
Textbook Reference: 57.5 How Does Species Richness Influence Community Stability?
Page: 1217
Bloom’s Category: 1. Remembering
56. In Tilman’s experiments, _______ declined as species richness increased.
a. productivity
b. species turnover
c. the amount of nitrogen left in the soil
d. All of the above
e. None of the above
Answer: c
Textbook Reference: 57.5 How Does Species Richness Influence Community Stability?
Page: 1217
Bloom’s Category: 1. Remembering
57. Tilman’s experiments showed that increasing species richness enhanced community
stability because
a. it increased the stability of each species’ performance.
b. different species performed better under different environmental circumstances.
c. it increased the likelihood of predation.
d. more nutrients remained in the soil in communities with few species.
e. None of the above; increasing species richness did not enhance community stability.
Answer: b
Textbook Reference: 57.5 How Does Species Richness Influence Community Stability?
Page: 1217
Bloom’s Category: 2. Understanding
58. Which of the following studies have been helpful in answering questions regarding
the use of monocultures?
a. Those on the effects of restoring wolves to Yellowstone
b. Robert Paine’s studies of keystone species in the rocky intertidal zones
c. Simberloff and Wilson’s experiments testing island biogeography models in the
Florida Keys
d. Those examining patterns of the succession in Glacier Bay
e. Tilman’s studies examining the relationship between species richness and community
stability
Answer: e
Textbook Reference: 57.5 How Does Species Richness Influence Community Stability?
Page: 1217–1218
Bloom’s Category: 2. Understanding
Fill in the Blank
1. The species that live and interact in a particular area constitute an ecological _______.
Answer: community
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
Bloom’s Category: 1. Remembering
2. Cows, which eat grass and other plant materials, belong to the _______ trophic level.
Answer: primary consumer (or herbivore)
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
3. Most species of spiders eat plant-eating insects. Spiders are thus primary _______, or
secondary _______.
Answer: carnivores; consumers
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
4. Many species of birds eat plants as well as other animals. They thus belong to the
_______ trophic level.
Answer: omnivore
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
5. Earthworms feed off of dead material and are thus considered _______.
Answer: detritivores (or decomposers)
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 1. Remembering
6. If gross primary productivity is 309 units and the respiration rate is 147 units, then net
primary productivity is _______ units.
Answer: 162
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 3. Applying
7. Although ecologists often diagram the interactions of who eats whom by means of a
food chain, depicting the complexity of real-life interactions often requires the
construction of a _______.
Answer: food web
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 1. Remembering
8. If 640 units of energy move through the primary producers of a community and 128
units move through the primary consumers, then the ecological efficiency is _______.
Answer: 0.2 (or 20%)
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 3. Applying
9. In the open ocean, the biomass of a community is usually highest at the _______
trophic level because the _______ have a high reproductive rate.
Answer: primary consumer; primary producers
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1207
Bloom’s Category: 2. Understanding
10. The reintroduction of wolves into Yellowstone in 1995 caused a decrease in the
population of _______. This decline enabled aspen seedlings to become reestablished.
Answer: elk
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1208
Bloom’s Category: 1. Remembering
11. The extinction of a predatory bird leads to an increase in the population size of a
small mammal, which in turn leads to a decrease in the population size of the plants on
which the mammal feeds. This is an example of a _______, which is caused by a series of
_______ effects.
Answer: trophic cascade; indirect
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1208
Bloom’s Category: 2. Understanding
12. Species such as beavers, which create structures in the environment that serve as
habitat for other species, are called _______.
Answer: ecosystem engineers
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 1. Remembering
13. Despite being so low in abundance that it is classified as a “near threatened” species,
the jaguar plays an important role in structuring forest communities. It is thus considered
a _______ species.
Answer: keystone
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 2. Understanding
14. The species composition of grasses changes little across communities in a grassland
biome; thus, the _______ diversity of grasses for this region is _______.
Answer: beta; low
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 2. Understanding
15. To quantify _______ diversity (diversity within a single community), biologists often
use the _______ diversity index, which takes into account relative abundance as well as
number of species.
Answer: alpha; Shannon
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 1. Remembering
16. Suppose there are 50 fish species in one lake and 30 in a neighboring lake. If the
Sorenson’s index of these lakes is 0.4, then _______ species would be shared by the two
lakes.
Answer: 16
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211
Bloom’s Category: 3. Applying
17. The theory of _______ biogeography was developed to explain _______
relationships.
Answer: island; species–area
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 1. Remembering
18. A freak cold spell in October 2009 in the northeastern United States dramatically
reduced the survival of several small mammal species. In this regard, the cold spell was
acting as a _______.
Answer: disturbance
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 2. Understanding
19. Gravel deposits formed where glacial fronts have remained stationary for many years
are known as _______.
Answer: moraines
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 1. Remembering
20. Succession is affected both by facilitation and by its opposite, _______.
Answer: inhibition
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1215
Bloom’s Category: 1. Remembering
21. David Tilman’s experiments showed that plots with more species are _______
productive.
Answer: more
Textbook Reference: 57.5 What Determines Species Richness in Ecological
Communities?
Page: 1217
Bloom’s Category: 1. Remembering
22. One reason that agricultural communities are often unstable is the practice of
_______, the planting of only a single species.
Answer: monoculture
Textbook Reference: 57.5 What Determines Species Richness in Ecological
Communities?
Page: 1218
Bloom’s Category: 1. Remembering
Diagram
1. Suppose the productivity of several test plots is artificially increased by adding
fertilizer to the soil. On the graph below, draw the expected relationship between
productivity and species diversity on these test plots.
Answer:
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206–1207
Bloom’s Category: 3. Applying
2.–4. Refer to the diagram below, showing island biogeography.
2. What is the equilibrium number of species for a large island?
a. 20
b. 40
c. 55
d. 80
e. It cannot be determined from the information given.
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 3. Applying
3. What is the equilibrium number of species for a small island?
a. 20
b. 40
c. 55
d. 80
e. It cannot be determined from the information given.
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 3. Applying
4. If a small island currently has 28 species, would the rate of immigration be greater
than, less than, or approximately equal to the rate of extinction?
Answer: Greater than
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 2. Understanding
5.–6. Suppose that an island fits the dynamics of the island biogeographic model. The
colonization of an island (C) is a function of the number of species (S) on the island: C =
e raised to the –0.1S. The extinction of species already on the island (X) is also a function
of S: X = (e raised to the 0.001S) – 1.
5. Graph the relationship of C as a function of S, and X as a function of S, for S between 5
and 100 at intervals of five (S = 5, 10, 15...).
Answer:
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 6. Creating
6. Based on your graph, what is the expected number of species at equilibrium?
Answer: Between 30 and 35
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
Bloom’s Category: 3. Applying
7. Based on the Tilman experiments, draw the expected relationship between species
diversity and productivity on the graph below.
Answer:
Textbook Reference: 57.5 What Determines Species Richness in Ecological
Communities?
Page: 1217
Bloom’s Category: 3. Applying
STUDY GUIDE QUESTIONS
(By Lindsay Goodloe)
Knowledge and Synthesis
1. The ecological community of a pond comprises
a. all the species living in the pond and the abiotic environment (water, sunlight, etc.) that
supports them.
b. all the species living in the pond.
c. the invertebrates and vertebrate animals living in the pond.
d. all of the producers and consumers living in the pond, but not the decomposers.
e. None of the above
Answer: b
Feedback: An ecological community comprises all of the populations living in a defined
area but excludes its nonliving components.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
2.–3. Refer to the food web below to answer the questions that follow.
2. Organism 9 is a(n)
a. herbivore.
b. primary carnivore.
c. secondary carnivore.
d. primary producer.
e. omnivore.
Answer: e
Feedback: Because organism 9 eats from both the primary producer level (1) and the
herbivore level (2), it is an omnivore.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205–1206
3. The food web has _______ trophic levels.
a. two
b. three
c. four
d. five
e. six
Answer: c
Feedback: Four trophic levels are depicted. The levels are primary producer (1),
herbivore (2, 3, 4), primary carnivore (5, 6), and secondary carnivore (7, 8). The
omnivore (9) occupies either the herbivore or primary carnivore level, depending on
whether it is feeding on a primary producer or on an herbivore.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205–1206
4. In which of the following ecosystems would you expect to observe the lowest biomass
of primary consumers relative to the biomass of the primary producers?
a. Tropical evergreen forest
b. Temperate grassland
c. Freshwater lake
d. Open ocean
e. Both c and d
Answer: a
Feedback: Compared to grasslands or aquatic ecosystems, forests typically have a lower
ratio of primary consumer biomass to primary producer biomass because trees (the
dominant primary producers) store energy for long periods of time in difficult-to-digest
forms.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206–1207
5. A plant in the dark uses 0.02 ml of O2 per minute. The same plant in sunlight releases
0.14 ml of O2 per minute. Its rate of gross primary production would be approximately
_______ ml of O2 per minute.
a. 0.02
b. 0.12
c. 0.14
d. 0.16
e. 0.18
Answer: d
Feedback: The amount of production used in maintenance and biosynthesis is added to
net primary production to determine gross primary production. Photosynthetic release of
O2 in the light is an estimate of net production; O2 use in the dark is an estimate of
maintenance and biosynthesis costs. You would add 0.02 ml to 0.14 ml to get an estimate
of gross primary production of 0.16 ml per minute.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
6. If the net primary productivity of a community is 2000 kcal/m2/yr, what would be the
best estimate of the productivity (in kcal/m2/yr) of the secondary consumers in that
community?
a. 4,000
b. 2,000
c. 200
d. 20
e. 2
Answer: d
Feedback: Net primary productivity is the rate at which energy is incorporated into the
bodies of primary producers through growth and reproduction. As a rule, only about 10
percent of the energy at one trophic level is transferred to the next. Because the secondary
consumers are two trophic levels above the primary producers, their productivity would
be expected to be only 1 percent of net primary productivity.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
7. Which of the following statements about the relationship between species richness and
productivity in ecological communities is true?
a. Species richness is usually highest in the most productive communities.
b. Species richness is usually highest in the least productive communities.
c. Species richness is frequently highest at an intermediate level of productivity.
d. Species richness is frequently lowest at an intermediate level of productivity.
e. Species richness is not correlated with productivity.
Answer: c
Feedback: Both observational and experimental evidence indicate that species richness
often peaks in communities of intermediate productivity.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206–1207
8. Which of the following statements about keystone species is true?
a. They are very abundant.
b. Their removal has a great effect on community structure.
c. They practice herbivory.
d. They have regular dispersion patterns.
e. They have clumped dispersion patterns.
Answer: b
Feedback: By definition, removal of a keystone species has a larger effect on the
community than would be expected based on its abundance.
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1209
9. Which of the following statements regarding species diversity is false?
a. If two communities have the same species richness, the one with the more even
distribution of species is considered more diverse.
b. Beta diversity is a measure of the change in species composition from one community
or habitat to another.
c. For many taxa, species diversity decreases with distance from the equator.
d. Gamma diversity is the regional diversity found over a range of communities or
habitats in a geographic region.
e. Sorenson’s index is used to estimate the alpha diversity of a community.
Answer: e.
Feedback: The Shannon diversity index measures alpha diversity. Sorenson’s index is
used to estimate the change in species composition from one community to another (i.e.,
beta diversity).
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210–1211
10. Refer to the graph below showing the effect of species number on arrival and
extinction rates. According to the theory of island biogeography, which of the following
statements about the graph is true?
a. Curve a is the arrival rate curve.
b. Curve b is the extinction rate curve.
c. The arrival rate equals the extinction rate at n1.
d. The extinction rate is zero at n1.
e. Both a and b
Answer: d
Feedback: The extinction rate is greater than zero and equals the arrival rate at n1, which
is therefore the equilibrium species number on the island.
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
11. In the figure below, the species numbers of many islands of different sizes were
plotted against their distance from the mainland, and data points for islands of similar
size were connected to form the four curves. Circle the letter of the curve corresponding
to the group of islands with the smallest size.
Answer: d
Feedback: Each curve corresponds to a group of similar-sized islands whose species
number is plotted against their distance from the mainland. For each curve, species
number decreases with distance from the mainland, and the curve that is lowest relative
to the vertical axis would be the group of smallest islands.
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
12. The theory of island biogeography makes predictions about the effects of species
number on the rate of extinction. Refer to the figure below, in which the solid curve
shows this relationship for a large island. Which of the curves shows the expected
relationship for a small island?
a. Curve a
b. Curve b
c. Curve c
d. Curve d
Answer: c
Feedback: With less space available, populations of the different species would be
smaller. This would subject them to higher extinction rates than would be expected on
larger islands.
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1212
13. Which of the following places stages of ecological succession occurring on glacial
moraines in Alaska in correct chronological sequence, from earliest to latest?
a. Increase in soil nitrogen; arrival of lichens; arrival of willows and alders; arrival of
conifers; arrival of bacteria, fungi, and photosynthetic microorganisms
b. Increase in soil nitrogen; arrival of bacteria, fungi, and photosynthetic microorganisms;
arrival of lichens; arrival of willows and alders; arrival of conifers
c. Arrival of bacteria, fungi, and photosynthetic microorganisms; increase in soil
nitrogen; arrival of lichens; arrival of willows and alders; arrival of conifers
d. Arrival of bacteria, fungi, and photosynthetic microorganisms; arrival of lichens;
arrival of willows and alders; increase in soil nitrogen; arrival of conifers
e. Arrival of bacteria, fungi, and photosynthetic microorganisms; arrival of conifers;
arrival of willows and alders; arrival of lichens; increase in soil nitrogen
Answer: d
Feedback: Of the stages listed, the arrival of bacteria, fungi and photosynthetic
microorganisms would be first. The arrival of lichens would be second, followed by the
arrival of willows and alders, an increase in soil nitrogen content, and finally the arrival
of conifers.
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214–1215
14. Which of the following represents primary succession?
a. The development of an aquatic community in a newly excavated farm pond, eventually
followed by the filling in of the pond with sediment and its conversion to a forest
b. The development of a terrestrial community on lava produced by a volcanic eruption
c. The gradual establishment of a forest following a fire that destroyed the previous
community
d. The invasion of weeds followed by shrubs and trees on an abandoned farm field
e. Both a and b
Answer: e
Feedback: Primary succession begins on a newly available site where all preexisting
living organisms have been stripped away, such as a freshly excavated pond or the
surface of lava. Succession that occurs after disturbances such as fire or the conversion of
a natural community to farmland is considered secondary.
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
15. Which of the following statements about succession is false?
a. Primary succession proceeds more rapidly than secondary succession.
b. Species that are early colonists may either facilitate or inhibit colonization by laterarriving species.
c. As succession proceeds, a lower proportion of the nutrients in a community are found
in abiotic forms.
d. As succession proceeds, food webs become more complex.
e. The endpoint of directional succession is the establishment of a self-perpetuating
climax community.
Answer: a
Feedback: Because primary succession begins on a site that is devoid of preexising
organisms, it is a slower process than secondary succession.
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214–1216
16. In comparison with temperate regions at higher latitudes, tropical communities show
greater species richness. Which of the following is a hypothesis that has been proposed to
explain this difference?
a. Tropical regions have had more time to diversify under stable climatic conditions.
b. Tropical regions have more habitat types.
c. Higher levels of interspecific competition in the tropics have led to narrower niches
and hence a greater number of more specialized species.
d. Higher predation intensity in the tropics prevents interspecific competition among prey
species and thus allows rare species to persist.
e. All of the above
Answer: e
Feedback: Community ecologists have not been able to agree on the reasons for the
greater species diversity characteristic of tropical communities. All four hypotheses have
been proposed, and each has some evidence to support it.
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211–1212
Application
1. Suppose that you are responsible for managing community succession to provide
suitable habitat for an endangered animal species that is long-lived and has a low
reproductive rate. Would you expect this species to be adapted to early or late
successional stages?
Answer: As explained in Chapter 55, long life span and low reproductive rate are typical
characteristics of K-strategists. Such species are typical of late successional stages.
Pioneer species, in contrast, are likely to be replaced quickly and therefore tend to be rstrategists with a high reproductive rate, short life span, and good dispersal ability.
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1215
2. Where do biomass pyramids like the one shown below occur, and what are the
conditions that create them?
Answer: In most aquatic ecosystems, the dominant primary producers are unicellular
algae. Their populations multiply so rapidly and are cropped so efficiently by slowergrowing herbivores that they frequently support a larger herbivore mass than their own.
Note that the diagram depicts an inverted pyramid of biomass. A pyramid of energy can
never be inverted.
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206–1207
3. How is an understanding of heterotrophic succession useful in the field of law
enforcement?
Answer: Heterotrophic succession occurs in communities whose energy source is detritus
such as human corpses. The community of organisms found on a decomposing corpse
can be used as evidence of the time since death.
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1216–1217
4. Generations of Americans have been instructed by Smokey Bear that fires are always
harmful to the environment and should be prevented under all circumstances. What are
some communities adapted to periodic fires? Explain why fires are beneficial to these
communities.
Answer: The lodgepole pine forests discussed in this chapter are an example of a
community that is maintained by periodic fires, which return nutrients to the soil and are
required for seed germination. Other examples of fire-dependent or fire-adapted
communities include tropical savanna and chaparral (described in Chapter 54). The use of
fire as a management tool to protect biodiversity is discussed in Chapter 59.
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1216
5. Wolves were reintroduced to Yellowstone National Park in 1995. Describe the
ecological effects within the park of this politically controversial decision.
Answer: In the Lamar Valley of the park, the reintroduction of wolves resulted in a
reduction of the population of elk, the wolves’ principle prey. In a trophic cascade, the
diminution in the number of elk led to increased tree reproduction of aspens and willows,
both of which had been heavily browsed by elk. In turn, the increase in the population of
streamside willows resulted in an increase in the number of beaver colonies in the valley.
Textbook Reference: 57.2 How Do Interactions among Species Influence Community
Structure?
Page: 1208
6. Growing crops as monocultures is standard practice in modern agriculture. Why are
monocultures unstable? What agricultural practices might result in more stable ecological
communities?
Answer: Monocultures are unstable because they are subject to attack by insect pests and
pathogens that destroy or damage crops. Experiments have shown that more diverse
agroecosystems in which two or more crops are grown on the same plot are less subject
to pest outbreaks. In corn–sweet potato dicultures, for example, sweet potato pests were
reduced because the corn provided a structural barrier, food for protective parasitoid
wasps, and chemicals that interfered with the ability of pests to find their host plants.
Textbook Reference: 57.5 How Does Species Richness Influence Community Stability?
Page: 1218
TEXTBOOK SELF-QUIZ
1. An ecological community is
a. a group of species that coexist and interact within a defined area.
b. a group of species that coexist and interact in an area together with the abiotic
environment.
c. all the species in an area that belong to a particular trophic level.
d. all the species that are members of a local food web.
e. All of the above
Answer: a
2. A trophic level consists of the organisms
a. whose energy has passed through the same number of steps to reach them.
b. that use similar foraging methods to obtain food.
c. that are eaten by a similar set of predators.
d. that eat both plants and other animals.
e. that compete with one another for food.
Answer: a
3. Net primary production is
a. the total amount of photosynthesis in a community.
b. the total amount of primary producer biomass available for consumption by
heterotrophs.
c. the total amount of biomass produced by all autotrophs and heterotrophs in a
community.
d. the total amount of biomass consumed by heterotrophs.
e. gross primary productivity minus secondaryproductivity.
Answer: b
4. Pyramid diagrams of energy and biomass distribution for forests and grasslands differ
because
a. forests are more productive than grasslands.
b. forests are less productive than grasslands.
c. large mammals avoid living in forests.
d. trees store much of their energy in difficult-to-digest wood, whereas grassland plants
produce few difficult-to-digest tissues.
e. grasses grow faster than trees.
Answer: d
5. Keystone species
a. influence the communities in which they live more than expected on the basis of their
abundance.
b. may influence the species richness of communities.
c. may influence the number of trophic levels in communities.
d. are not necessarily predators.
e. All of the above
Answer: e
6. Species diversity
a. increases with latitude from the equator to the temperate zone.
b. decreases with latitude from the equator to the temperate zone.
c. shows no consistent pattern from the equator to the temperate zone.
d. increases with latitude from the equator to the temperate zone for terrestrial organisms
and decreases with latitude from the equator to the temperate zone for aquatic organisms.
e. increases with latitude from the equator to the temperate zone for animals and
decreases with latitude from the equator to the temperate zone for plants.
Answer: b
7. The theory of island biogeography
a. predicts that the equilibrium number of species on an island is a balance between the
rate of immigration of new species and the rate of extinction of resident species.
b. predicts that the rate of immigration of new species will decline with island distance
from the mainland species pool.
c. predicts that the rate of extinction of resident species will decrease as island size
increases.
d. applies to isolated habitat patches as well as to oceanic islands
e. All of the above
Answer: e
8. Ecological succession is
a. the change in species over time.
b. the change in community composition after a disturbance.
c. the change in a forest as the trees grow larger.
d. the process by which a species becomes abundant.
e. the buildup of soil nutrients.
Answer: b
9. Primary succession begins
a. soon after a disturbance ends.
b. at varying times after a disturbance ends.
c. at sites where some organisms have survived a disturbance.
d. at sites where no organisms have survived a disturbance.
e. at sites where only primary producers have survived a disturbance.
Answer: d
10. Early stages of succession are characterized by
a. species that are good dispersers.
b. species with high intrinsic rates of reproduction.
c. simple food webs.
d. nutrients that are available primarily in abiotic sources.
e. All of the above
Answer: e
BIOPORTAL DIAGNOSTIC QUIZ (Personalized Study Plan Quiz)
(By Nancy Murray)
1. Populations of species living close enough together for potential interactions constitute
a(n)
a. ecosystem.
b. community.
c. population.
d. food web.
e. symbiosis.
Answer: b
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
Bloom’s Category: 2. Understanding
2. The species that live and interact in an area constitute a(n)
a. lek.
b. population.
c. ecological community.
d. ecosystem.
e. biome.
Answer: c
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1204
Bloom’s Category: 2. Understanding
3. In the equation for net primary production, would you ever expect R to be zero?
a. Yes, but only when the system is at equilibrium.
b. Yes, but only when the system is out of equilibrium.
c. No, unless the system is at equilibrium.
d. No, unless the system is out of equilibrium
e. No, because there would be no life if R was zero.
Answer: e
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 3. Applying
4. In most aquatic systems, the dominant photosynthesizers are
a. bacteria
b. protists
c. Amoebae
d. Both a and b
e. Both a and c
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
5. In a trophic level, primary producers
a. receive their energy from the sun.
b. receive their energy by consuming animals.
c. receive their energy by consuming plants.
d. receive their energy from minerals in the soil.
e. decompose waste products.
Answer: a
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
6. Divisions of organisms in a community, based on the way in which they obtain their
energy, is/are called
a. a food chain.
b. trophic levels.
c. food webs.
d. pyramids.
e. consumers.
Answer: b
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1205
Bloom’s Category: 2. Understanding
7. Food webs indicate
a. how species are related.
b. all of the primary consumers.
c. the detritivores that recycle nutrients.
d. the trophic interactions in a community.
e. the amount of biomass in a community.
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206
Bloom’s Category: 2. Understanding
8. Most of the biomass of a grassland is found in
a. animals.
b. the soil.
c. the atmosphere.
d. green plants.
e. water.
Answer: d
Textbook Reference: 57.1 What Are Ecological Communities?
Page: 1206–1207
Bloom’s Category: 2. Understanding
9. Species whose influences on ecosystems are greater than would be expected, based on
their abundance, are called
a. primary producers.
b. secondary consumers.
c. flagged species.
d. keystone species.
e. disturbance specialists.
Answer: d
Textbook Reference: 57.2 How Do Interactions Among Species Influence Community
Structure?
Page: 1209
Bloom’s Category: 2. Understanding
10. The Shannon Index is a mathematical expression used to measure diversity that takes
both species richness and species evenness into account. A higher H value
a. indicates a higher certainty about species composition and greater diversity.
b. indicates a lower certainty about species composition and less diversity.
c. indicates a lower certainty about species composition and greater diversity.
d. indicates a higher certainty about species composition and less diversity.
e. None of the above
Answer: c
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1210
Bloom’s Category: 3. Applying
11. Which of the following hypotheses is not related to the latitudinal diversity gradient?
a. The time hypothesis
b. The trophic hypothesis
c. The spatial heterogeneity hypothesis
d. The specialization hypothesis
e. The predation hypothesis
Answer: b
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1211–1212
Bloom’s Category: 2. Understanding
12. Refer to the figure below. What can you conclude about the results of the experiment
shown?
a. Recolonization occurred fastest on islands closest to the mainland.
b. Recolonization of the arthropods reached pre-experimental levels and stabilized.
c. Recolonization was random and the distance from the mainland was not a factor.
d. Both a and b
e. All of the above
Answer: a
Textbook Reference: 57.3 What Patterns of Species Diversity Have Ecologists Observed?
Page: 1213
Bloom’s Category: 4. Analyzing
13. Which of the following is not an example of succession?
a. A pond changing to a meadow
b. The self-perpetuation of a climax community
c. Shrubs filling in a forest gap
d. The recolonization of Mount St. Helens after its eruption
e. A forest being clear-cut
Answer: b
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 2. Understanding
14. The gradual process of environmental change and species replacement is called
a. predation.
b. area effect.
c. zonation.
d. commensalism.
e. succession.
Answer: e
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 2. Understanding
15. Organisms that are most likely to tolerate harsh conditions are found during
a. early primary succession.
b. late primary succession.
c. secondary succession.
d. early climax stage.
e. late climax stage.
Answer: a
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 2. Understanding
16. Primary succession is least likely to occur after which of the following?
a. A rainstorm
b. A volcanic eruptions
c. A fire
d. An outbreaks of disease
e. A tornado
Answer: a
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214
Bloom’s Category: 2. Understanding
17. Although the consequences of various kinds of disturbances are highly variable, their
results conform to a general pattern. This general pattern is called
a. succession.
b. general disturbance.
c. disaster equilibrium.
d. general equilibrium.
e. intermediate equilibrium.
Answer: a
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214–1215
Bloom’s Category: 2. Understanding
18. In 1988, Yellowstone National Park experienced fires affecting over 36 percent of its
area. What can you predict happened after the fires died out?
a. Primary succession occurred.
b. The land was colonized by invasive species which prevented native species from
returning.
c. Secondary succession occurred.
d. Directional succession occurred.
e. Both c and d
Answer: e
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1214–1215
Bloom’s Category: 3. Applying
19. Heterotrophic succession
a. is a type of succession in which the energy reserves become depleted and there is no
mechanism to restore them.
b. is a type of succession in which there are no energy reserves at the onset and they are
produced over time as colonization takes place.
c. is commensalism.
d. All of the above
e. None of the above
Answer: a
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1216
Bloom’s Category: 2. Understanding
20. A change in community composition following a disturbance is called _______
succession.
a. primary
b. secondary
c. ecological
d. disaster
e. equilibrium
Answer: c
Textbook Reference: 57.4 How Do Disturbances Affect Ecological Communities?
Page: 1217
Bloom’s Category: 2. Understanding