Practice Exam 2 - B - Community Ecology
1 Which of the following statements is consistent with the principle of competitive exclusion? Select only ONE answer
choice.
A. Bird species generally do not compete for nesting sites.
B. The density of one competing species will have a positive impact on the population growth of the other competing
species.
C. Two species with a different fundamental niche will exclude the other competing species.
D. Even a slight competitive advantage will eventually lead to the elimination of the less well adapted of two
competing species if they share the same resource which is also limited.
2 True or False: According to the competitive exclusion principle, two species cannot continue to occupy the same niche.
A. True
B. False
3 Dwarf mistletoes are flowering plants that grow on certain forest trees. They obtain
nutrients and water from the tissues of the trees. The trees derive no known benefits
from the dwarf mistletoes. Which of the following best describes the interactions
between dwarf mistletoes and trees? Select only ONE answer choice.
A. mutualism
B. commensalism
C. parasitism
D. competition
4 Evidence shows that some grasses benefit from being grazed. Considering this evidence, which of the following terms
would best describe this plant-herbivore interaction? Select only ONE answer choice.
A. mutualism
B. parasitism
C. competition
D. predation
5 White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees.
The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, while the White-
breasted nuthatch searches from the top of the trunk down. These hunting behaviors best illustrate which of the following
ecological concepts? Select only ONE answer choice.
A. resource partitioning
B. character displacement
C. keystone species
D. parasitism
6 In a tide pool, 15 species of invertebrates were reduced to eight after one species was removed. The species removed
was likely a(n):
Select only ONE answer choice.
A. community facilitator.
B. keystone species.
C. herbivore.
D. resource partitioner.
E. mutualistic organism.
7 Residents of a lake populated by pike, a carnivorous fish, have recently noticed that new fishing regulations allowing
increased fishing activity have decreased the lake’s pike population, causing a rise in the population of smaller fishes that
eat zooplankton. At the same time, they have seen algal blooms increase dramatically. Based on these observations, what
ecological process is most likely to be occurring in this lake?
A. A trophic cascade
B. Competitive exclusion
C. Resource partitioning
, D. Change in the fundamental niche of pike
8 Two species of closely related swallows live in England.
The black swallow lives in coniferous (e.g. pine) forests, and
the yellow swallow lives predominantly in deciduous (e.g. oak)
forests. However, in areas where black swallows are not
present, the yellow swallow is capable of living in both
deciduous and coniferous forests. In Ireland, where the black
swallow has never been introduced, yellow swallows are
observed in both coniferous and deciduous forests.
True or False: The absence of Yellow Swallows from English
coniferous forests could be a result of competitive exclusion.
A. True
B. False
9 Which of the following types of species interaction is correctly paired with its effects on the density of the two interacting
populations? Select only ONE answer choice.
A. predation: as one increases, the other increases
B. parasitism: both decrease
C. commensalism: as one increases the other stays the same
D. mutualism: both decrease
E. competition: both increase
10 The figures below show the results of an experiment in
which two microbial species, A and B, were grown in three
treatments. In treatment I, species A was grown alone. In
treatment II, species B was grown alone. In treatment III,
both species were grown together at the same starting
densities as in I and II.
The results suggest the interaction is best described as…
Select only ONE answer choice.
A. Competitive
B. Parasitic
C. Predatory
D. Mutualistic
The symbols +, -, and o are to be used to show the results of interactions between individuals and groups of individuals in
the examples that follow. The symbol + denotes a positive interaction, - denotes a negative interaction, and o denotes
where individuals are not affected by interacting. The first symbol refers to the first organism mentioned.
11 What interactions exist between a lion pride and a hyena pack (both hunt the same large mammals)? Select only ONE
answer choice.
A. +/+
B. +/o
C. +/-
D. o/o
E. -/-
1 Which of the following statements is consistent with the principle of competitive exclusion? Select only ONE answer
choice.
A. Bird species generally do not compete for nesting sites.
B. The density of one competing species will have a positive impact on the population growth of the other competing
species.
C. Two species with a different fundamental niche will exclude the other competing species.
D. Even a slight competitive advantage will eventually lead to the elimination of the less well adapted of two
competing species if they share the same resource which is also limited.
2 True or False: According to the competitive exclusion principle, two species cannot continue to occupy the same niche.
A. True
B. False
3 Dwarf mistletoes are flowering plants that grow on certain forest trees. They obtain
nutrients and water from the tissues of the trees. The trees derive no known benefits
from the dwarf mistletoes. Which of the following best describes the interactions
between dwarf mistletoes and trees? Select only ONE answer choice.
A. mutualism
B. commensalism
C. parasitism
D. competition
4 Evidence shows that some grasses benefit from being grazed. Considering this evidence, which of the following terms
would best describe this plant-herbivore interaction? Select only ONE answer choice.
A. mutualism
B. parasitism
C. competition
D. predation
5 White-breasted nuthatches and Downy woodpeckers both eat insects that hide in the furrows of bark in hardwood trees.
The Downy woodpecker searches for insects by hunting from the bottom of the tree trunk to the top, while the White-
breasted nuthatch searches from the top of the trunk down. These hunting behaviors best illustrate which of the following
ecological concepts? Select only ONE answer choice.
A. resource partitioning
B. character displacement
C. keystone species
D. parasitism
6 In a tide pool, 15 species of invertebrates were reduced to eight after one species was removed. The species removed
was likely a(n):
Select only ONE answer choice.
A. community facilitator.
B. keystone species.
C. herbivore.
D. resource partitioner.
E. mutualistic organism.
7 Residents of a lake populated by pike, a carnivorous fish, have recently noticed that new fishing regulations allowing
increased fishing activity have decreased the lake’s pike population, causing a rise in the population of smaller fishes that
eat zooplankton. At the same time, they have seen algal blooms increase dramatically. Based on these observations, what
ecological process is most likely to be occurring in this lake?
A. A trophic cascade
B. Competitive exclusion
C. Resource partitioning
, D. Change in the fundamental niche of pike
8 Two species of closely related swallows live in England.
The black swallow lives in coniferous (e.g. pine) forests, and
the yellow swallow lives predominantly in deciduous (e.g. oak)
forests. However, in areas where black swallows are not
present, the yellow swallow is capable of living in both
deciduous and coniferous forests. In Ireland, where the black
swallow has never been introduced, yellow swallows are
observed in both coniferous and deciduous forests.
True or False: The absence of Yellow Swallows from English
coniferous forests could be a result of competitive exclusion.
A. True
B. False
9 Which of the following types of species interaction is correctly paired with its effects on the density of the two interacting
populations? Select only ONE answer choice.
A. predation: as one increases, the other increases
B. parasitism: both decrease
C. commensalism: as one increases the other stays the same
D. mutualism: both decrease
E. competition: both increase
10 The figures below show the results of an experiment in
which two microbial species, A and B, were grown in three
treatments. In treatment I, species A was grown alone. In
treatment II, species B was grown alone. In treatment III,
both species were grown together at the same starting
densities as in I and II.
The results suggest the interaction is best described as…
Select only ONE answer choice.
A. Competitive
B. Parasitic
C. Predatory
D. Mutualistic
The symbols +, -, and o are to be used to show the results of interactions between individuals and groups of individuals in
the examples that follow. The symbol + denotes a positive interaction, - denotes a negative interaction, and o denotes
where individuals are not affected by interacting. The first symbol refers to the first organism mentioned.
11 What interactions exist between a lion pride and a hyena pack (both hunt the same large mammals)? Select only ONE
answer choice.
A. +/+
B. +/o
C. +/-
D. o/o
E. -/-
