Ch4 Population ecology
True/False
Indicate whether the statement is true or false.
____
1. To determine how many members of a population are in a given area, an ecologist would study the
population’s dispersion.
____
2. Density-dependent limiting factors would include a forest fire.
____
3. In the lag stage of a logistic growth curve, the population size increases slowly.
____
4. The study of demographics helps to predict changes in the human population.
____
5. The human population growth rate has always increased.
____
6. For thousands of years, the human population remained about the same because birth rates and deathrates
were the same.
____
7. The concept of carrying capacity is used to explain why many populations exhibit increasing population size.
____
8. The spatial distribution of a population is seldom limited by biotic or abiotic factors.
____
9. Carrying Capacity for human populations is always easy to identify.
____ 10. Unlike other organisms, humans have control to raise their carrying capacity.
____ 11. Immigration and emigration are more important to population growth than natality and mortality.
____ 12. Logistic growth has J shaped curve.
____ 13. Carrying capacity will eventually limit an s curved growing population.
____ 14. In a harsh and constant changing environment, K-statigist organisms thrive.
____ 15. Since 1970, Human population growth has been in decline.
Multiple Choice
Identify the choice that best completes the statement or answers the question.
____ 16. Density, distribution, and growth rate are characteristics used to classify which one of the following?
a. biomes
c. limiting factors
b. populations
d. age structure
____ 17. Which of the following does not affect the spatial distribution of a population?
a. the carrying capacity of a population
b. the distribution of food and other resources
c. abiotic conditions like rainfall and sunlight
d. the existence of predators or parasites
____ 18. Which of the following involves a situation in which a density-dependent factor influences a population?
a. Several seasons passed during which rainfall was ample, winters were not severe and food
for snow hares was in good supply.
b. A hurricane severely disrupted a salt marsh and uprooted most of the marsh grass in an
estuary.
c. A forest fire on the north side of a mountain forced the white-tailed deer from the north
____ 19.
____ 20.
____ 21.
____ 22.
____ 23.
____ 24.
____ 25.
____ 26.
____ 27.
____ 28.
side to move into the range of the white-tailed deer on the south side of the mountain,
making food more scarce.
d. After a heavy rain, pesticides that were applied to a cotton crop to control weevils ran off
into a waterway that flows next to a field.
On ten acres of native forest there are eight white-tailed deer, seven coyotes, 45 armadillos, and 231 loblolly
pine trees. Which population has the highest density?
a. white-tailed deer
c. armadillos
b. coyotes
d. loblolly pine trees
American bison, which are large grazing mammals, are most often found clumped in small groups. What
might you infer about the spatial distribution of American bison?
a. A clumped group provides better protection from predators.
b. A clumped group attracts more prey.
c. A clumped group can graze a larger area.
d. A clumped group takes better advantage of water resources.
A flowering plant has seeds that are carried by the wind. Infer the most likely dispersion pattern of the plants
that grow from these seeds.
a. uniform
c. random
b. clumped groups
d. spatial
Which of the following statements is correct?
a. Population size of predators increases when their prey is scarce.
b. Competition for resources is density-independent when food is plentiful.
c. Disease is density-dependent because transmission of the disease is affected by numbers
d. A change in average temperature is a density-dependent factor because fewer organisms
can acclimate to variations in temperature.
Young adult male chimpanzees look for mates outside their own population. The males then take the females
back to their group. Which of the following occured to the population the females came from?
a. emigration
c. mortality
b. immigration
d. natality
To assess a population’s current growth , an ecologist must know how many individuals are born, how many
died, and how many move away in a given period of time. What else must an ecologist know?
a. how many individuals find mates
b. how many individuals move in from somewhere else
c. how many individuals carry communicable diseases
d. how many individuals are young or old
You are an ecologist collecting data about the declining growth rate of the critically endangered Philippine
eagle. The eagles’ only known population is estimated to have about 350–650 individuals. Which of the
following can you assume is zero?
a. natality
c. emigration
b. mortality
d. immigration
How does the logistic model of population growth differ from the exponential model?
a. The exponential model shows a restricted growth rate.
b. The logistic model considers the environment’s carrying capacity.
c. The graph of the exponential model is S shaped.
d. The graph of the logistic model has a longer lag phase.
A fruit fly that has a short life span and produces many offspring can be classified into which reproductive
strategy?
a. r-strategist
c. a carrying-capacity strategist
b. k-strategist
d. a logistic strategist
Which characteristic is typical of a k-strategist?
____ 29.
____ 30.
____ 31.
____ 32.
____ 33.
____ 34.
____ 35.
a. short life span
b. generally a small organism
c. produces many offspring
d. lengthy parental care of young
Which of the following methods might be used to decrease the rate of approach to carrying capacity by the
developed world?
a. increase birthrate
b. decrease death rate
c. decrease resource use
d. decrease emigration
What is likely to be true of a population with an age structure that is pyramid shaped?
a. It is expected to grow slowly in the future.
b. It is expected to decline in population size over time.
c. It has more pre-reproductive and reproductive males and females with few elderly.
d. This age structure is characteristic of zero population growth.
Which country would most likely have a declining birthrate?
a. a primarily agricultural country
b. an industrially developed country
c. a country changing from an agricultural economy to an industrial economy
d. economy does not affect birthrate
Which event is correlated with the beginning of exponential growth in human population?
a. the start of the Industrial Revolution
b. the invention of agriculture
c. the bubonic plague epidemic
d. the end of the Second World War
The worlds population has reached...
a. 6.5 billion
c. 7 million
b. 7 billion
d. 6.5 million
The country of Bulgaria has a negative growth rate of – 0.89 percent. The rate of immigration is 2% percent
and the rate of emigration is – 2% percent. How do the birthrate and death rate of Bulgaria compare given
these numbers?
a. The birthrate and death rate are equal in value.
b. The birthrate has a higher value than the death rate.
c. The birthrate has a lower value than the death rate.
d. The birthrate and death rate are both zero.
Which age-structure pattern reflects a population with a declining population?
a. the pre-reproductive, reproductive and post-reproductive age classes are of equal sizes
b. the pre-reproductive age classes are larger than the reproductive or post-reproductive age
classes
c. the reproductive age classes are smaller than pre- and post-reproductive age classes
d. the youngest, or pre-reproductive, age classes are the smallest
Completion
Complete each statement.
36. A population’s ________ (a. growth rate, b. disperssion rate) is the amount that a population’s size changes in
a given period of time.
37. A previously rapidly growing population of green tree frogs in the city park has suddenly leveled off, and is
presently neither increasing or decreasing in numbers. You can probably infer that the tree frog population has
reached its ___________ (a. abiotic limit b. carying capacity).
38. The size of a population will decrease if mortality ________ (a. increases b. decreases)
39. The three major causes of human deaths throughout recorded history are war, famine, and ___________ (a.
disease b. natural disasters)
40. Complete the following equation:
(a. carrying rate b. birthrate)___________ – death rate + immigration rate – emigration rate = growth
rate
Ch4 Population ecology
Answer Section
TRUE/FALSE
1. ANS: F
The number of individuals in a population that are in a given area is the population density. The population’s
dispersion patterns are how the population is distributed within the area.
PTS: 1
DIF: Bloom's Level C | DOK 1
NAT: LS_4d
TOP: 4-3
2. ANS: T
Density-dependent factors operate on dense populations.
REF: 92
PTS: 1
DIF: Bloom's Level D | DOK 2
REF: 95
NAT: LS_4d
STA: LS.10.16
TOP: 4-2
3. ANS: T
The use of available resources is exponential throughout the growth of a population, even in the lag stage.
When the resources become limited, population growth slows as illustrated by the logistic curve.
PTS: 1
DIF: Bloom's Level E | DOK 2
REF: 97
NAT: LS_4d
TOP: 4-2
4. ANS: T
Demography is the study of human population size, density, distribution, movement, and birth and death
rates.
PTS: 1
DIF: Bloom's Level B | DOK 2
REF: 100
TOP: 4-4
5. ANS: F
There are several notable dips in the graph of the growth of the human population. One, for example, is the
dip caused by the millions of deaths from bubonic plague in the mid 1300s.
PTS: 1
DIF: Bloom's Level A | DOK 2
REF: 101
NAT: LS_4d
TOP: 4-4
6. ANS: T
Earth’s natural carrying capacity was the same as it is now, without the number of humans that currently
inhabit Earth. The human population remained about the same for much of human history because, although
birthrates were high, death rates were high also. After the human death rate was lowered through
improvements in medicine and public sanitation, the human population begin to grow exponentially.
PTS: 1
NAT: LS_4d
DIF: Bloom's Level A | DOK 2
STA: LS.11.8
TOP: 4-4
REF: 101
MODIFIED TRUE/FALSE
7. ANS: F, stable or constant
PTS: 1
NAT: LS_4d
DIF: Bloom's Level B | DOK 2
STA: LS.11.8
TOP: 4-2
REF: 98
8. ANS: F, always
PTS: 1
NAT: LS_5e
9. ANS: F, hard
DIF: Bloom's Level F | DOK 2
STA: LS.10.16
TOP: 4-3
REF: 94
PTS: 1
NAT: LS_4d
10. ANS: T, resources
DIF: Bloom's Level D | DOK 2
TOP: 4-6
REF: 105
PTS: 1
NAT: LS_4e
11. ANS: F, less
DIF: Bloom's Level E | DOK 2
STA: LS.10.16
TOP: 4-6
REF: 105
PTS: 1
12. ANS: F, s curved
PTS: 1
13. ANS: T, limit
PTS: 1
14. ANS: F, R
PTS: 1
15. ANS: F, rise
PTS: 1
MULTIPLE CHOICE
16. ANS: B
Populations are members of the same species that live in a certain area. They are often described using
measurements of density, distribution, and growth rate.
Feedback
A
B
C
D
Check on page 92.
You are right!
That's not it.
Try again.
PTS: 1
DIF: Bloom's Level B | DOK 2
REF: 92
NAT: LS_4d
STA: LS.10.16
TOP: 4-1
17. ANS: A
The spatial distribution of a population is affected by the biotic and abiotic resources found in particular areas.
The carrying capacity by itself does not affect spatial distribution.
Feedback
A
B
Correct!
Try again.
C
D
Abiotic factors do affect the spatial distribution of populations.
Check on page 94 for more information.
PTS: 1
DIF: Bloom's Level B | DOK 2
REF: 94
NAT: LS_5e
STA: LS.10.16
TOP: 4-3
18. ANS: C
Rainfall, weather, and pesticides are density-independent factors in an environment. A forest fire is also
density-independent, but the movement of the deer into a population on the other side of the mountain is
immigration. This increases the density of the south-side deer causing increased competition for food.
Feedback
A
B
C
D
Remind yourself of what density-dependent factors are.
Is a hurricane a density-dependent factor?
Correct. Immigration increases density in a population.
Rain and pesticides are not density-dependent factors.
PTS: 1
DIF: Bloom's Level D | DOK 2
REF: 94–95
NAT: LS_4d
STA: LS.10.16
TOP: 4-2
19. ANS: D
All of the organisms live on the same ten acres. There are 8 deer/10 acres, 7 coyotes/10 acres, 45
armadillos/10 acres, and 231 trees/10 acres. There are many more trees per acre than any of the other
organisms, and so the trees have the highest density.
Feedback
A
B
C
D
Remind yourself of the way density is calculated.
There are fewer coyotes than any of the other organisms.
See page 92 for help.
This is correct.
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 92
TOP: 4-1
20. ANS: A
American bison, though large, are herbivorous animals that are prey to several predators in their habitat.
American bison clump themselves in small groups because multiple animals on the lookout for predators
provide more safety for each of the individuals in the group.
Feedback
A
B
C
D
Correct!
Remember that bison are prey, not predators.
Does this make sense?
Try again.
PTS: 1
DIF: Bloom's Level E | DOK 2
REF: 92
NAT: LS_5e
TOP: 4-3
21. ANS: C
The wind does not distribute seeds in a uniform manner, or in a clumped group. The wind carries seeds and
drops them randomly in unpredictable places where they may take root and grow.
Feedback
A
B
C
D
Try again.
That's not it.
Correct.
Check on page 92.
PTS: 1
DIF: Bloom's Level F | DOK 2
REF: 92
NAT: LS_5e
TOP: 4-3
22. ANS: C
Disease is density-dependent because when individuals are closer together, disease spreads more easily.
Feedback
A
B
C
D
Try again.
Read more about competition on page 96.
Correct!
Is this a density-dependent factor?
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 96
NAT: LS_4d
STA: LS.10.16
TOP: 4-2
23. ANS: A
The females’ original population experiences a decrease in population size when the females leave the group.
Emigration occurs when members of a population leave a location.
Feedback
A
B
C
D
Correct!
Are the females leaving their original population or moving in?
Mortality is the death rate.
Natality is the birthrate.
PTS: 1
DIF: Bloom's Level D | DOK 2
REF: 97
STA: LS.10.16
TOP: 4-3
24. ANS: B
The four factors that influence a population’s growth rate are natality (how many are born), mortality (how
many die), emigration (how many move away), and immigration (how many move in).
Feedback
A
B
C
D
Try again.
You're right!
This is not quite right.
Check on page 97.
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 97
NAT: LS_4d
STA: LS.10.16
TOP: 4-1
25. ANS: D
If the population of eagles being studied is the only known population, then immigration of individuals into
the population from somewhere else is unlikely.
Feedback
A
B
There are probably some birds being born.
Some of the birds are probably dying.
C
D
Try again.
Correct!
PTS: 1
DIF: Bloom's Level E | DOK 2
REF: 97
NAT: LS_4d
STA: LS.10.16
TOP: 4-1
26. ANS: B
The graph of the logistic model of population growth indicates a leveling off of population growth associated
with the environment’s carrying capacity.
Feedback
A
B
C
D
Refer page 97 again.
That is correct.
Try again.
Remember that the models differ when the population reaches carrying capacity.
PTS: 1
DIF: Bloom's Level D | DOK 1
REF: 97
NAT: LS_4d
TOP: 4-2
27. ANS: A
An r-strategist is characterized by a short life span and the production of many offspring.
Feedback
A
B
C
D
Correct.
Refer to page 98 for more help.
Try again.
Logistic refers to a type of population growth model.
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 98
NAT: LS_4d
TOP: 4-2
28. ANS: D
k-strategists typically have few offspring and high parental investment.
Feedback
A
B
C
D
Refer to page 99 for more help.
Review the characteristics of k-strategists.
Try again after you review the two reproductive strategies.
Correct.
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 99
NAT: LS_4d
TOP: 4-2
29. ANS: C
The approach to the carrying capacity is influenced by the number of humans and the resources used per
person, which is high in developed countries.
Feedback
A
B
C
D
This would have the opposite effect.
This would have the opposite effect.
That's right!
The carrying capacity is a global limit; it's not possible to move away from it.
PTS: 1
DIF: Bloom's Level F | DOK 2
REF: 105
NAT: LS_4d
STA: LS.11.8
TOP: 4-4
30. ANS: C
The large number of young individuals will reach reproductive age and increase the birthrate, thus increasing
the population growth rate.
Feedback
A
B
C
D
What factors influence growth rate?
Refer to page 104 for more information.
That's right!
Consider what will happen to the birthrate.
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 104
NAT: LS_4d
TOP: 4-5
31. ANS: B
An industrially developed country with a high standard of living, high average levels of education, low death
rate, and technological advances, also tends to have a low or declining birthrate.
Feedback
A
B
C
D
Read page 102 for more information.
Correct!
Developing countries tend to have a high birthrate. Try again.
Try again.
PTS: 1
DIF: Bloom's Level E | DOK 2
REF: 102
STA: LS.11.4
TOP: 4-4
32. ANS: A
The beginning of the Industrial Revolution is about the time the human population began growing
exponentially.
Feedback
A
B
C
D
Right!
Human populations did not show a dramatic growth after this event in history.
Review page 100.
The growth in human population began to increase well before this time.
PTS: 1
DIF: Bloom's Level C | DOK 1
REF: 100
NAT: LS_4d
TOP: 4-4
33. ANS: B
In Afghanistan 48 people will be added to the population of every thousand people in one year. In Niger 26
people will be added to the population of every thousand people in one year. As a result, 48 – 26 = 22 more
people will be added to the population of Afghanistan per thousand per year.
Feedback
A
B
C
D
Do the estimate for 1000 people.
Correct!
Try simple subtraction.
This is not a difference.
PTS: 1
DIF: Bloom's Level C | DOK 2
REF: 103
NAT: LS_4d
TOP: 4-4
34. ANS: C
People are not born fast enough to replace the ones who die, resulting in a declining population size, or a
negative growth rate. This means that the birthrate has a lower value than the death rate.
Feedback
A
B
C
D
Check page 101.
Would this result in a negative growth rate?
Correct!
This would result in a population with no change in size.
PTS: 1
DIF: Bloom's Level E | DOK 2
REF: 103
NAT: LS_4d
TOP: 4-4
35. ANS: D
A negatively growing population will show fewer individuals in the pre-reproductive age classes because of
the low birthrate.
Feedback
A
B
C
D
This suggests a population that's replacing its members.
This characterizes a population about to grow, think about the effect of a declining
birthrate.
Does this suggest a low birthrate?
Right!
PTS: 1
NAT: LS_4d
DIF: Bloom's Level D | DOK 2
TOP: 4-5
REF: 104
COMPLETION
36. ANS: a. growth rate
PTS: 1
DIF: Bloom's Level B | DOK 1
NAT: LS_4d
TOP: 4-1
37. ANS: b. carrying capacity
REF: 97
PTS: 1
NAT: LS_4d
38. ANS: a. increases
DIF: Bloom's Level D | DOK 2
STA: LS.11.8
TOP: 4-2
REF: 98
PTS: 1
NAT: LS_4d
39. ANS: a. disease
DIF: Bloom's Level C | DOK 1
TOP: 4-1
REF: 97
PTS: 1
NAT: LS_4d
40. ANS: b. birthrate
DIF: Bloom's Level D | DOK 1
TOP: 4-4
REF: 102–103
DIF: Bloom's Level D | DOK 2
REF: 101
PTS: 1
NAT: LS_4d
TOP: 4-4