Bio250 Final Exam Questions with Accurate
Solutions
Q1.11. What is an ecological community?
a) A group of individuals from a given species that interact
b) A population with a shared set of beliefs and a common idenity
c) A set of populations that share a defined area and interact
d) A population that interacts with its environment
c
Q1.12. A disturbance is any relatively discrete event in time that does which of the following?
A. Disrupts ecosystem, community or population structure
B. Changes resources, substrate availability, or the physical environment
C. Facilitates succession
D. Both A and B
D
Q1.13. Early-successional plant species are characterized by life-history traits that do which of
the following?
A. Enable them to grow under tall, shady trees
,B. Allow them to grow large but require them to grow slowly
C. Enable them to arrive at a site and establish quickly after a disturbance
D. Both A and B
C
Q1.14. Following a disturbance to a site, any species that arrives at the site survives. Once an
individual plant establishes itself, it will survive or not depending on how well it competes for
light, water, and nutrients. As a result, over time, species that are poorer competitors are
replaced by species that are better competitors. Which model of succession best explains this
pattern?
a) Facilitation
b) Inhibition
c) Tolerance
c
Q2.15. A large number of breeding birds in Yellowstone nest and feed in stands of aspen,
willow and cottonwood. How do you think the return of the wolf will impact these
populations?
a) By increasing tree abundance, wolves will directly reduce bird population sizes.
b) By decreasing tree abundance, wolves will indirectly reduce bird population sizes.
c) By increasing tree abundance, wolves will indirectly boost bird population sizes.
,d) Because wolves do not directly interact with trees, they are unlikely to impact bird
population sizes.
c
Q2.16. Pileated Woodpeckers (Dryocopus pileatus) excavate large (>45 cm) cavities in trees
that they use for nests and roosts. Wood Ducks (Aix spons) also build nests in suitable tree
holes, but cannot excavate their own cavities. Consequently, they frequently use nests of
Pileated Woodpeckers. Based on this information, which of the following statements is
correct?
a) Wood Ducks are ecosystem engineers because they nest in cavities built by woodpeckers.
b) Pileated Woodpeckers are ecosystem engineers because they excavate tree cavities that
Wood Ducks use to build their nests.
c) Pileated Woodpeckers are ecosystem engineers because they excavate tree cavities to
build their own nests.
d) Neither species is an ecosystem engineer by virtue of their nesting habit.
b
Q2.17. Which of the following statements about trophic cascades is TRUE?
a) A trophic cascade occurs when predation limits herbivore abundance, and plant population
sizes are reduced.
b) A trophic cascade occurs when a predator is removed, allowing plants to expand, which
then limits herbivores.
c) In a trophic cascade, plant abundance depends on the number of trophic levels in the
, community.
d) A behavioral cascade, which often involves the perception of predation risk, is not a type
of trophic cascade.
c
Q3.3. Many community ecologists are concerned about the effects of habitat fragmentation.
In particular they worry that clear-cutting of old growth forests will produce small, isolated
forest patches and that species will be lost from these smaller patches because small patches
cannot support as long a food chain as bigger patches. This concern is based on which of the
following hypotheses discussed in this chapter?
a) The productivity hypothesis
b) The ecosystem-size hypothesis
c) The exploitation ecosystem hypothesis
d) HSS's the 'world is green' hypothesis
b
Q3.4. A wildlife biologist has adopted a number of techniques to protect the Willow
Flycatcher, a bird that often nests and feeds in willows. Some techniques reflect top-down
while some reflect bottom-up control. Which of the following approaches demonstrates her
understanding of how top-down forces affect community dynamics?
a) The biologist attempts to increase food availability by reintroducing beaver. She
hypothesizes that beaver will raise the water table, stimulating the growth of willow, which
will result in an increase in insect abundance, giving flycatchers more food.
Solutions
Q1.11. What is an ecological community?
a) A group of individuals from a given species that interact
b) A population with a shared set of beliefs and a common idenity
c) A set of populations that share a defined area and interact
d) A population that interacts with its environment
c
Q1.12. A disturbance is any relatively discrete event in time that does which of the following?
A. Disrupts ecosystem, community or population structure
B. Changes resources, substrate availability, or the physical environment
C. Facilitates succession
D. Both A and B
D
Q1.13. Early-successional plant species are characterized by life-history traits that do which of
the following?
A. Enable them to grow under tall, shady trees
,B. Allow them to grow large but require them to grow slowly
C. Enable them to arrive at a site and establish quickly after a disturbance
D. Both A and B
C
Q1.14. Following a disturbance to a site, any species that arrives at the site survives. Once an
individual plant establishes itself, it will survive or not depending on how well it competes for
light, water, and nutrients. As a result, over time, species that are poorer competitors are
replaced by species that are better competitors. Which model of succession best explains this
pattern?
a) Facilitation
b) Inhibition
c) Tolerance
c
Q2.15. A large number of breeding birds in Yellowstone nest and feed in stands of aspen,
willow and cottonwood. How do you think the return of the wolf will impact these
populations?
a) By increasing tree abundance, wolves will directly reduce bird population sizes.
b) By decreasing tree abundance, wolves will indirectly reduce bird population sizes.
c) By increasing tree abundance, wolves will indirectly boost bird population sizes.
,d) Because wolves do not directly interact with trees, they are unlikely to impact bird
population sizes.
c
Q2.16. Pileated Woodpeckers (Dryocopus pileatus) excavate large (>45 cm) cavities in trees
that they use for nests and roosts. Wood Ducks (Aix spons) also build nests in suitable tree
holes, but cannot excavate their own cavities. Consequently, they frequently use nests of
Pileated Woodpeckers. Based on this information, which of the following statements is
correct?
a) Wood Ducks are ecosystem engineers because they nest in cavities built by woodpeckers.
b) Pileated Woodpeckers are ecosystem engineers because they excavate tree cavities that
Wood Ducks use to build their nests.
c) Pileated Woodpeckers are ecosystem engineers because they excavate tree cavities to
build their own nests.
d) Neither species is an ecosystem engineer by virtue of their nesting habit.
b
Q2.17. Which of the following statements about trophic cascades is TRUE?
a) A trophic cascade occurs when predation limits herbivore abundance, and plant population
sizes are reduced.
b) A trophic cascade occurs when a predator is removed, allowing plants to expand, which
then limits herbivores.
c) In a trophic cascade, plant abundance depends on the number of trophic levels in the
, community.
d) A behavioral cascade, which often involves the perception of predation risk, is not a type
of trophic cascade.
c
Q3.3. Many community ecologists are concerned about the effects of habitat fragmentation.
In particular they worry that clear-cutting of old growth forests will produce small, isolated
forest patches and that species will be lost from these smaller patches because small patches
cannot support as long a food chain as bigger patches. This concern is based on which of the
following hypotheses discussed in this chapter?
a) The productivity hypothesis
b) The ecosystem-size hypothesis
c) The exploitation ecosystem hypothesis
d) HSS's the 'world is green' hypothesis
b
Q3.4. A wildlife biologist has adopted a number of techniques to protect the Willow
Flycatcher, a bird that often nests and feeds in willows. Some techniques reflect top-down
while some reflect bottom-up control. Which of the following approaches demonstrates her
understanding of how top-down forces affect community dynamics?
a) The biologist attempts to increase food availability by reintroducing beaver. She
hypothesizes that beaver will raise the water table, stimulating the growth of willow, which
will result in an increase in insect abundance, giving flycatchers more food.
