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Campbell’s Biology, 9e (Reece et al.)
Chapter 53 Population Ecology
Chapter 53 helps students develop an understanding of the baseline of ecology by learning about
populations. A plethora of questions will help to confirm student understanding of the basic concepts of
population ecology. Some questions require students to apply what they have learned in a calculation or
scenario. In addition, questions about the human population will challenge students to use what they
have learned to make decisions about, and evaluations of, the future of humans on our planet. In the
chapters that follow, students will integrate the concept of population into an understanding of
community ecology and eventually ecosystems.
Multiple-Choice Questions
1) Population ecologists are primarily interested in
A) studying interactions among populations of organisms that inhabit the same area.
B) understanding how biotic and abiotic factors influence the density, distribution, size, and age
structure of populations.
C) how humans affect the size of wild populations of organisms.
D) how populations evolve as natural selection acts on heritable variations among individuals and
changes in gene frequency.
E) the overall vitality of a population of organisms.
2) A population is correctly defined as having which of the following characteristics?
I. inhabiting the same general area
II. belonging to the same species
III. possessing a constant and uniform density and dispersion
A) I only
B) III only
C) I and II only
D) II and III only
E) I, II, and III
3) An ecologist recorded 12 white-tailed deer, Odocoileus virginianus, per square mile in one woodlot
and 20 per square mile in another woodlot. What was the ecologist comparing?
A) density
B) dispersion
C) carrying capacity
D) cohorts
E) range
4) During the spring, you are studying the mice that live in a field near your home. The population
density is high, but you realize that you rarely observe any reproductive female mice. This most likely
indicates
A) that there is selective predation on female mice.
B) that female mice die before reproducing.
C) that this habitat is a good place for mice to reproduce.
D) that you are observing immigrant mice.
E) that the breeding season is over.
5) Uniform spacing patterns in plants such as the creosote bush are most often associated with
A) chance.
B) patterns of high humidity.
C) the random distribution of seeds.
D) competitive interaction between individuals of the same population.
E) the concentration of nutrients within the population’s range.
6) Which of the following groups would be most likely to exhibit uniform dispersion?
A) red squirrels, who actively defend territories
B) cattails, which grow primarily at edges of lakes and streams
C) dwarf mistletoes, which parasitize particular species of forest tree
D) moths, in a city at night
E) lake trout, which seek out cold, deep water high in dissolved oxygen
7) To construct a reproductive table for a sexual species, one needs to
A) assess sperm viability for the males in the population.
B) keep track of all of the offspring of a cohort.
C) keep track of the females in a cohort.
D) keep track of all of the offspring of the females in a cohort.
E) analyze the ratio of deaths to births in a cohort.
8) Which of the following examples would most accurately measure the density of the population being
studied?
A) counting the number of prairie dog burrows per hectare
B) counting the number of times a 1 kilometer transect is intersected by tracks of red squirrels after a
snowfall
C) counting the number of coyote droppings per hectare
D) multiplying the number of moss plants counted in 10 quadrats of 1m2 each by 100 to determine the
density per kilometer2.
E) counting the number of zebras from airplane census observations.
9) Which of the following assumptions have to be made regarding the capture-recapture estimate of
population size?
I. Marked and unmarked individuals have the same probability of being trapped.
II. The marked individuals have thoroughly mixed with the population after being marked.
III. No individuals have entered or left the population by immigration or emigration, and no individuals
have been added by birth or eliminated by death during the course of the estimate.
A) I only
B) II only
C) I and II only
D) II and III only
E) I, II, and III
10) Long-term studies of Belding’s ground squirrels show that immigrants move nearly 2 km from
where they are born and become 1%-8% of the males and 0.7%-6% of the females in other populations.
On an evolutionary scale, why is this significant?
A) These immigrants make up for the deaths of individuals, keeping the other populations’ size stable.
B) Young reproductive males tend to stay in their home population and are not driven out by other
territorial males.
C) These immigrants provide a source of genetic diversity for the other populations.
D) Those individuals that emigrate to these new populations are looking for less crowded conditions
with more resources.
E) Gradually, the populations of ground squirrels will move from a clumped to a uniform population
pattern of dispersion.
11) Which of the following sets of measurements is the most useful when studying populations?
A) density, dispersion, and demographics of a population
B) gene frequency over time and the ratio of reproductive to nonreproductive individuals
C) annual precipitation averages and mean annual temperatures
D) minimum and maximum amounts of precipitation and annual temperature extremes
E) ratio of predators and the number of immigrants and emigrants
12) Which of the following scenarios would provide the most legitimate data on population density?
A) Count the number of nests of a particular species of songbird and multiply this by a factor that
extrapolates these data to actual animals.
B) Count the number of pine trees in several randomly selected 10 m x 10 m plots and extrapolate this
number to the fraction of the study area these plots represent.
C) Use the mark-and-recapture method to estimate the size of the population.
D) Calculate the difference between all of the immigrants and emigrants to see if the population is
growing or shrinking.
E) Add the number of births and subtract the individuals that die to see if the population’s density is
increasing or decreasing.
13) Which of the following is the best example of uniform distribution?
A) bees collecting pollen in a wildflower meadow
B) snails in an intertidal zone at low tide
C) territorial songbirds in a mature forest during mating season
D) mushrooms growing on the floor of an old growth forest
E) a cultivated cornfield in the Midwest
14) Which of the following choices would most likely promote random distribution?
A) territorial species
B) species that secrete chemicals to attract or inhibit other individuals
C) flocking and schooling behaviors
D) spacing during the breeding season
E) homogeneous chemical and physical factors in the environment
15) Which of the following best defines a cohort?
A) a group of individuals that inhabits a small isolated region within the range for the species
B) all of the individuals that are annually added to a population by birth and immigration
C) the reproductive males and females within the population
D) a group of the individuals from the same age group, from birth until they are all dead
E) the number of individuals that annually die or emigrate out of a population
16) Why do some invertebrates, such as lobsters, show a “stair-step” survivorship curve?
A) Many invertebrates mate and produce offspring on multiyear cycles.
B) Within a species of invertebrates, younger individuals have a higher survivorship than older
individuals.
C) Many invertebrates molt in order to grow, and they are vulnerable to predation during their “soft
shell” stage.
D) Many invertebrate species have population cycles that go up and down according to the frequency of
sunspots.
E) The number of fertilized eggs that mature to become females in many species of invertebrates is
based on ambient temperature.
17) Which of the following is the most important assumption for the capture-recapture method to
estimate the size of wildlife populations?
A) All females in the population have the same litter size.
B) More individuals emigrate from, as opposed to immigrate into, a population.
C) Over 50% of the marked individuals need to be trapped during the recapture phase.
D) There is a 50:50 ratio of males to females in the population before and after trapping and recapture.
E) Marked individuals have the same probability of being recaptured as unmarked individuals during the
recapture phase.
18) A population of ground squirrels has an annual per capita birth rate of 0.06 and an annual per capita
death rate of 0.02. Calculate an estimate of the number of individuals added to (or lost from) a
population of 1,000 individuals in one year.
A) 120 individuals added
B) 40 individuals added
C) 20 individuals added
D) 400 individuals added
E) 20 individuals lost
19) Exponential growth of a population is represented by dN/dt =
A)
rN
K
B) rN
C) rN (K + N)
D) rN
()KN
K
−
E) rN
()NK
K
−
20) Starting from a single individual, what is the size of a population of bacteria that reproduce by
binary fission every 20 minutes at the end of a 2-hour time period? (Assume unlimited resources and no
mortality.)
A) 6
B) 18
C) 128
D) 512
E) 1,024
21) Which of the following is the equation for zero population growth (ZPG)?
A) R = b – m
B) dN/dt = rN
C) dN/dt =rmax N (K -N)/K
D) dN/dt =rmax N
E) dN/dt = 1.0N
22) In July 2008, the United States had a population of approximately 302,000,000 people. How many
Americans were there in July 2009, if the estimated 2008 growth rate was 0.88%?
A) 2,700,000
B) 5,500,000
C) 303,000,000
D) 304,000,000
E) 2,710,800,000
23) In 2008, the population of New Zealand was approximately 4,275,000 people. If the birth rate was
14 births for every 1,000 people, approximately how many births occurred in New Zealand in 2008?
A) 6,000
B) 42,275
C) 60,000
D) 140,000
E) 600,000
24) Consider two forests: one is an undisturbed old-growth forest, while the other has recently been
logged. In which forest are species likely to experience exponential growth, and why?
A) Old growth, because of stable conditions that would favor exponential growth of all species in the
forest.
B) Old growth, because each of the species is well established and can produce many offspring.
C) Logged, because the disturbed forest affords more resources for increased specific populations to
grow.
D) Logged, because the various populations are stimulated to a higher reproductive potential.
E) Exponential growth is equally probable in old-growth and logged forests.
25) Logistic growth of a population is represented by dN/dt =
A)
rN
K
B) rN
C) rN (K + N)
D) rN
()KN
K
−
E) rN
()NK
K
−
26) As N approaches K for a certain population, which of the following is predicted by the logistic
equation?
A) The growth rate will not change.
B) The growth rate will approach zero.
C) The population will show an Allee effect.
D) The population will increase exponentially.
E) The carrying capacity of the environment will increase.
27) In models of logistic population growth,
A) the population growth rate slows dramatically as N approaches K.
B) new individuals are added to the population most rapidly at the beginning of the population’s growth.
C) new individuals are added to the population as N approaches K.
D) only density-dependent factors affect the rate of population growth.
E) carrying capacity is never reached.
28) The Allee effect is used to describe a population that
A) has become so small that it will have difficulty surviving and reproducing.
B) has become so large that it will have difficulty surviving and reproducing.
C) is viable and stable at its carrying capacity.
D) has exceeded its carrying capacity.
E) is in crash decline.
29) Carrying capacity is
A) seldom reached by marine producers and consumers because of the vast resources of the ocean.
B) the maximum population size that a particular environment can support.
C) fixed for most species over most of their range most of the time.
D) determined by density and dispersion data.
E) the term used to describe the stress a population undergoes due to limited resources.
30) Which of the following causes populations to shift most quickly from an exponential to a logistic
population growth?
A) increased birth rate
B) removal of predators
C) decreased death rate
D) competition for resources
E) favorable climatic conditions
31) Which of the following statements about the evolution of life histories is correct?
A) Stable environments with limited resources favor r-selected populations.
B) K-selected populations are most often found in environments where density-independent factors are
important regulators of population size.
C) Most populations have both r– and K-selected characteristics that vary under different environmental
conditions.
D) The reproductive efforts of r-selected populations are directed at producing just a few offspring with
good competitive abilities.
E) K-selected populations rarely approach carrying capacity.
32) Natural selection involves energetic trade-offs between
A) choosing how many offspring to produce over the course of a lifetime and how long to live.
B) producing large numbers of gametes when employing internal fertilization versus fewer numbers of
gametes when employing external fertilization.
C) the emigration of individuals when they are no longer reproductively capable or committing suicide.
D) increasing the number of individuals produced during each reproductive episode with a
corresponding decrease in parental care.
E) high survival rates of offspring and the cost of parental care.
33) The three basic variables that make up the life history of an organism are
A) life expectancy, birth rate, and death rate.
B) number of reproductive females in the population, age structure of the population, and life
expectancy.
C) age when reproduction begins, how often reproduction occurs, and how many offspring are produced
per reproductive episode.
D) how often reproduction occurs, life expectancy of females in the population, and number of offspring
per reproductive episode.
E) the number of reproductive females in the population, how often reproduction occurs, and death rate.
34) Which of the following pairs of reproductive strategies is consistent with energetic trade-off and
reproductive success?
A) Pioneer species of plants produce many very small, highly airborne seeds, whereas large elephants
that are very good parents produce many offspring.
B) Female rabbits that suffer high predation rates may produce several litters per breeding season, and
coconuts produce few fruits, but most survive when they encounter proper growing conditions.
C) Species that have to broadcast to distant habitats tend to produce seeds with heavy protective seed
coats, and animals that are caring parents produce fewer offspring with lower infant mortality.
D) Free-living insects lay thousands of eggs and provide no parental care, whereas flowers take good
care of their seeds until they are ready to germinate.
E) Some mammals will not reproduce when environmental resources are low so they can survive until
conditions get better, and plants that produce many small seeds are likely found in stable environments.
35) Pacific salmon and annual plants are excellent examples of
A) cohort disintegration.
B) dispersion.
C) Allee effect.
D) iteroparous reproduction.
E) semelparous reproduction.
36) Which of the following is characteristic of K-selected populations?
A) offspring with good chances of survival
B) many offspring per reproductive episode
C) small offspring
D) a high intrinsic rate of increase
E) early parental reproduction
37) Which variables define the ecological life history of a species?
A) the age at which reproduction begins, frequency of reproduction, and the number of offspring for
each reproductive episode
B) the ratio of females to males, the length of the breeding season, and the number of offspring for each
reproductive episode
C) the number of offspring produced over a lifetime by a breeding pair and the survivability of the
offspring
D) timing breeding sessions with optimal environmental conditions and the number of offspring
produced during each breeding session
E) the amount of parental care given after birth, the number of reproductive episodes per year, and the
number of years females are capable of producing viable offspring
38) Which pattern of reproduction is correctly paired with a species?
A) iteroparity Pacific salmon
B) iteroparity elephant
C) semelparity oak tree
D) semelparity rabbit
E) semelparity–polar bear
39) Often the growth cycle of one population has an effect on the cycle of another. As moose
populations increase, for example, wolf populations also increase. Thus, if we are considering the
logistic equation for the wolf population,
dN/dt = rN
()KN
K
−
,
which of the factors accounts for the effect on the moose population?
A) r
B) N
C) rN
D) K
E) dt
40) In which of the following situations would you expect to find the largest number of K-selected
individuals?
A) a recently abandoned agricultural field in Ohio
B) the sand dune communities of south Lake Michigan
C) the flora and fauna of a coral reef in the Caribbean
D) South Florida after a hurricane
E) a newly emergent volcanic island
41) Which of the following is most likely to contribute to density-dependent regulation of populations?
A) the removal of toxic waste by decomposers
B) intraspecific competition for nutrients
C) earthquakes
D) floods
E) fires
42) Why do populations grow more slowly as they approach their carrying capacity?
A) Density-dependent factors lead to fewer births and increased mortality.
B) Density-independent factors lead to fewer births and increased mortality.
C) Hormonal changes promote higher death rates in crowded populations.
D) Individuals voluntarily stop mating so that overcrowding does not occur.
E) The incoming energy decreases in populations experiencing a high rate of increase.
43) A population of white-footed mice becomes severely overpopulated in a habitat that has been
disturbed by human activity. Sometimes intrinsic factors cause the population to increase in mortality
and lower reproduction rates to occur in reaction to the stress of overpopulation. Which of the following
is an example of intrinsic population control?
A) Owl populations frequent the area more often because of increased hunting success.
B) Females undergo hormonal changes that delay sexual maturation and many individuals suffer
depressed immune systems and die due to the stress of overpopulation.
C) Clumped dispersion of the population leads to increased spread of disease and parasites, resulting in a
population crash.
D) All of the resources (food and shelter) are used up by overpopulation and much of the population dies
of exposure and/or starvation.
E) Because the individuals are vulnerable they are more likely to die off if a drought or flood were to
occur.
44) Why is territoriality an adaptive behavior for songbirds maintaining populations at or near their
carrying capacity?
A) Songbirds expend a tremendous amount of energy defending territories so that they spend less time
feeding their young and fledgling mortality increases.
B) Only the fittest males defend territories and they attract the fittest females so the best genes are
conveyed to the next generation.
C) Songbird males defend territories commensurate with the size from which they can derive adequate
resources for themselves, their mate, and their chicks.
D) Many individuals are killed in the agonistic behaviors that go along with territorial defense.
E) Adult songbirds make improvements to the territories they inhabit so that they can produce
successfully fledged chicks.
45) Which of the following could be a density-independent factor limiting human population growth?
A) social pressure for birth control
B) earthquakes
C) plagues
D) famines
E) pollution
46) An ecological footprint is a construct that is useful
A) for a person living in a developed nation to consider to make better choices when using global food
and energy resources.
B) for a person living in a developing country to see how much of the world’s resources are left for
him/her.
C) in converting human foods’ meat biomass to plant biomass.
D) in making predictions about the global carrying capacity of humans.
E) in determining which nations produce the least amount of carbon dioxide from the burning of fossil
fuels.
47) Which of the following was the most significant limiting factor in human population growth in the
20th century?
A) famine
B) non-HIV disease
C) HIV
D) genocide
E) clean water
48) Which of the following is most key to understanding the demographic transition in human
population growth?
A) education of global famine
B) improved worldwide health care
C) voluntary reduction of family size
D) improved sanitary conditions in the world’s hospitals
E) reduction of casualties of war
49) Why does the 2009 U.S. population continue to grow even though the United States has essentially
established a ZPG?
A) emigration
B) immigration
C) better sanitation
D) baby boomer reproduction
E) the 2007-2009 economic recession
50) Which statement is true with regard to human population growth?
A) It is at a zero reproduction rate.
B) Its rate of increase continues to grow at an exponential rate.
C) Its rate of growth is slowing.
D) Its rate of growth is increasing.
E) There is no scientific prediction that can be made about human population growth.
Art Questions
Use the survivorship curves in Figure 53.1 to answer the following questions.
Figure 53.1
51) Which curve best describes survivorship in marine molluscs?
A) A
B) B
C) C
D) D
E) E