Chapter 4
COMPLETION
2. As _______________ species, many sharks play crucial roles in helping to keep their ecosystems
functioning.
ANS: keystone
3. ____________________ diversity is the most obvious component of biodiversity.
ANS: Species
4. The best guess of the total number of species on earth is between __________ and __________.
ANS: 8 million; 100 million
5. Large regions such as forests and deserts, with distinct climates and species, are called
_______________.
ANS: biomes
6. Among his many accomplishments, Edward O. Wilson is working on Harvard University’s
____________________, an online database of the earth’s known and name species.
ANS: Encyclopedia of Life
21. A 2005 study found an apparent correlation between ____________________ and the extinction
of about two-thirds of 110 known species of harlequin frog in Central and South America.
ANS:
global warming
climate change
22. If a species of frog becomes threatened by a change in environmental conditions, the species
would be considered a(n) ____________________.
ANS: indicator species
23. The loss of a(n) ____________________ species can lead to population crashes and extinctions
of other species in a community that depend on it.
ANS: keystone
PTS: 1
Ecosystem?
DIF: Easy
TOP: 4-6 What Roles Do Species Play in an
24. ____________________ keystone species feed on and help regulate the populations of other
species in an ecosystem.
ANS: Top predator
PTS: 1
Ecosystem?
DIF: Easy
TOP: 4-6 What Roles Do Species Play in an
25. Butterflies, hummingbirds, and bats play a keystone role in some ecosystems by
____________________ plant species.
ANS: pollinating
PTS: 1
Ecosystem?
DIF: Easy
TOP: 4-6 What Roles Do Species Play in an
Chapter 5
TRUE/FALSE
1. The southern sea otter is a tool-using mammal.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-0 Core Case Study
2. The most common interaction between species is commensalism.
ANS: F
PTS: 1
TOP: 5-1 How Do Species Interact?
DIF: Easy
3. Humans compete with many other species for space, food, and other resources.
ANS: T
PTS: 1
TOP: 5-1 How Do Species Interact?
DIF: Easy
4. Detritus feeders and decomposers are considered predators.
ANS: F
PTS: 1
TOP: 5-1 How Do Species Interact?
DIF: Easy
5. Animal predators tend to kill the sick, weak, aged, and least fit members of a species, therefore
increasing the fitness of the prey species.
ANS: T
PTS: 1
TOP: 5-1 How Do Species Interact?
DIF: Easy
6. In predator-prey relationships, the predator is seeking food for itself and its offspring, while the
prey is seeking not to become food for the predator. As a result, predator and prey populations
exert tremendous natural selection pressures on each other.
ANS: T
PTS: 1
TOP: 5-1 How Do Species Interact?
DIF: Easy
7. At the population level parasites are always harmful to the host species.
ANS: F
PTS: 1
TOP: 5-1 How Do Species Interact?
DIF: Easy
8. Species whose ecological niches overlap will be in competition for whatever the resource is in the
overlap.
ANS: T
PTS: 1
DIF: Moderate
TOP: 5-2 What Limits the Growth of Populations?
9. Hawaiian honeycreepers have evolved into species with specialized niches, which has increased
the competition between these species.
ANS: F
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
10. There are always limits to population growth in nature.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
11. Organisms with clumped distribution are fairly rare.
ANS: F
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
12. A population will most likely increase if it is made up mostly of individuals in the ‘reproductive’
or ‘near reproductive’ stages.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
13. A population's growth rate will increase as the population reaches its carrying capacity.
ANS: F
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
14. The carrying capacity of any given area is not fixed.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
15. An example of top-down population regulation in predator-prey species is predation.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
16. Humans are exempt from population overshoot and dieback.
ANS: F
PTS: 1
DIF: Easy
TOP: 5-2 What Limits the Growth of Populations?
17. Large mammals, such as humans, whales, and elephants, are especially vulnerable to extinction
because of their reproductive patterns.
ANS: T
PTS: 1
DIF: Moderate
TOP: 5-2 How Can Natural Selection Reduce Competition between Species?
18. In communities and ecosystems the types and numbers of species change in response to changing
environmental conditions.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-3 How Do Communities and Ecosystems Respond to Changing Environmental
Conditions?
19. Scientists have changed their view about a stable type of climax community as the end product of
succession and are now suggesting we can not predict the course of succession.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-3 How Do Communities and Ecosystems Respond to Changing Environmental
Conditions?
20. Grasslands have a high resilience and therefore can quickly recover following a fire.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-3 How Do Communities and Ecosystems Respond to Changing Environmental
Conditions?
21. Succession leads inevitably toward an ideally adapted climax plant community or ecosystem.
ANS: F
PTS: 1
DIF: Moderate
TOP: 5-3 How Do Communities and Ecosystems Respond to Changing Environmental
Conditions?
22. Primary and secondary succession tend to increase biodiversity and the sustainability of
communities and ecosystems.
ANS: T
PTS: 1
DIF: Easy
TOP: 5-3 How Do Communities and Ecosystems Respond to Changing Environmental
Conditions?
COMPLETION - chapter
1. The southern sea otter has been classified as a(n) ____________________ species.
ANS: keystone
2. ____________________ is a competitive interaction between species for food and/or space.
ANS: Interspecific competition
3. ____________________ occurs when a member of one species feeds directly on all or part of a
member of another species.
ANS: Predation
4. In _______________ two species behave in ways that benefit both by providing each with needed
resources.
ANS: mutualism
5. The most common interaction between species is ____________________.
ANS: competition
6. When two or more species compete with one another their niches are said to
____________________.
ANS: overlap
7. The concept that no two species can occupy the same ecological niche for an extended period of
time is known as the ____________________.
ANS: competitive exclusion principle
8. When two different species interact over a long time, changes in the gene pool help both species
to become more competitive or avoid competition. This is called _______________,
ANS: coevolution
9. Species that are bad-tasting, bad-smelling, toxic, or stinging-prey species advertise their
characteristics using ____________________.
ANS: warning coloration
10. Some prey species make themselves larger, startle the predator, or mimic a predator, all of which
are called ____________________.
ANS: behavioral strategies
11. ____________________ is like an arms race between interacting populations of different species.
ANS: Coevolution
12. Vast armies of ____________________ inhabit the digestive tracts of humans and help break
down or digest their food.
ANS: bacteria
13. Five warblers in the state of Maine have evolved to share food resources and reduce food
competition through ____________________.
ANS: resource partitioning
14. The most common form of population dispersion found in nature is ____________________.
ANS: clumped
15. Individuals in populations with a high intrinsic rate of growth typically reproduce
____________________ and have short ____________________ times.
ANS: early in life; generation
16. A population exceeding its carrying capacity suffers a(n) ____________________ or
____________________, unless the excess individuals can switch to new resources or move to a
new area.
ANS:
dieback; crash
crash; dieback
17. ____________________ is the combination of all factors that act to limit the growth of a
population.
ANS: Environmental resistance
18. A plot of the number of individuals in a population against time yields a sigmoid or S-shaped
curve, typical of ____________________ growth.
ANS: logistic
19. A species whose population size fluctuates slightly above and below its carrying capacity is said
to have a fairly ____________________ population size.
ANS: stable
20. The gradual change in species composition in a given area is called ____________________.
ANS: ecological succession
21. One of the factors determining at what rate succession occurs is _______________, in which one
set of species makes an area suitable for other species with different requirements.
ANS: facilitation
22. ____________________ involves the gradual establishment of biotic communities in lifeless
areas where there is no soil.
ANS: Primary succession
23. Systems, such as the global climate, can reach a(n) ____________________, where any
additional stress can cause the system to change in an abrupt and usually unpredictable way that
often involves collapse.
ANS: tipping point