1. Chapter
5
Populations

2. 5 – 1 How Populations Grow
Characteristics of Populations
• Three important characteristics of a population are:
1. geographic distribution - _________________________________________________
2. density - ______________________________________________________________
3. growth rate - ___________________________________________________________
Population Growth
• Three factors can affect population size:
1.
2.
3.
Exponential Growth
• Under ideal conditions with unlimited resources, a population will grow
exponentially
Exponential growth - ______________________________________________________
_______________________________________________________________________
_
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3. Logistic Growth
• Obviously, the conditions for logistic growth are rarely ever met
• As resources become less available, the growth of a population slows or stops
Logistic Growth - _________________________________________________________
_______________________________________________________________________
_
_______________________________________________________________________
_
Q: Why does this happen?
A:
Carrying Capacity - _______________________________________________________
_______________________________________________________________________
Q: What is the growth rate when a population is at carrying capacity?
A:
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4. Name ___________________________________ Date ___________________ Per ____
5 – 1 Section Review
1. List three characteristics that are used to describe a population.
2. What factors can change a population’s size?
3. What is the difference between exponential growth and logistic growth?
4. What is meant by population density?
5. Define carrying capacity.
6. What factors might cause the carrying capacity of a population to change?
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5. 5 – 2 Limits to Growth
Limiting Factor – ________________________________________________________
_______________________________________________________________________
Ex.)
• A resource base that is limited can also affect the long term survival of a species
Density – dependent Factors
• Limiting factors that depend on _______________________________________
• Density dependent factors become limiting only when the population density reaches
a certain level
• These factors operate most strongly when a population is large and dense
• Density dependent factors include: ________________________________________
_______________________________________________________________________
_
Density – Independent Factors
• Affect all populations in similar ways regardless of the population
Ex.)
• In response to such factors, many species show a characteristic crash in population
size
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6. • Environments are always changing, and most populations can adapt to a certain
amount of change
• Populations often grow and shrink in response to such changes
• Major upsets in an ecosystem can lead to long term declines in certain populations
Name ___________________________________ Date ___________________ Per ____
5 – 2 Section Review
1. List three density-dependent factors and three density-independent factors that can limit
the growth of a population.
2. What is the relationship between competition and population size?
3. If an entire lynx population disappears, what is likely to happen to the hare population
on which it preys?
4. Give an example of a density-independent limiting factor that has affected a human
population. Describe how this factor changed the human population.
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7. 5 – 3 Human Population Growth
Historical Overview
• Like the populations of many other living organisms, the size of the human
population tends to increase with time
• In the U.S. and other developed countries, the current growth is _________________
• In some developing countries, the human population is growing at a rate of
________________________________________
• The human population is well on its way to reaching __________________________
in your lifetime
Exponential Human Growth
• The following factors have caused a rapid increase in population growth
• •
• •
• •
•
Patterns of Population Growth
Q: Why can’t the human population keep growing exponentially forever?
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8. A:
Demography - ___________________________________________________________
• Birthrates, death rates, and age structure of a population help to protect why some
countries have a high growth rate while others grow more slowly
The Demographic Transition
Age Structure
• Population growth depends, in part on how many people of different ages make up a
given population
age-structure diagrams - ____________________________________________________
_______________________________________________________________________
_
_______________________________________________________________________
_
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9. Future Population Growth
World Population: 1950 - 2050
Year Average Annual Population
Growth Rate (%)
1.47 2,555,360,972
1950
1.33 3,039,669,330
1960
2.19 3,136,556,092
1962
2.19 3,206,072,286
1963
2.07
1970 3,708,067,105
1.69
1980 4,454,607,332
1.58 5,275,407,789
1990
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10. 1.23
2000 6,078,684,329
1.06
2010 6,812,009,338
.87
2020 7,515,218,898
.68
2030 8,127,227,506
.54 8,646,671,023
2040
.43 9,078,850,714
2050
Name ___________________________________ Date ___________________ Per ____
5 – 3 Section Review
1. Describe the general trend of human population growth that has occurred over time.
2. What factors explain why populations in different countries grow at different rates?
3. What is demography?
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11. 4. Describe the demographic transition and explain how it might affect a country’s
population growth rate.
5. Why do you think age-structure diagrams can help predict future population trends?
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