Biology - Chp 5 - Populations - Notes
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Biology - Chp 5 - Populations - Notes






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Biology - Chp 5 - Populations - Notes Biology - Chp 5 - Populations - Notes Document Transcript

  • Chapter 5 Populations
  • 5 – 1 How Populations GrowCharacteristics 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 exponentiallyExponential growth - ______________________________________________________________________________________________________________________________ 2
  • Logistic Growth• Obviously, the conditions for logistic growth are rarely ever met• As resources become less available, the growth of a population slows or stopsLogistic Growth - _________________________________________________________________________________________________________________________________________________________________________________________________________Q: Why does this happen?A:Carrying Capacity - ______________________________________________________________________________________________________________________________Q: What is the growth rate when a population is at carrying capacity?A: 3
  • Name ___________________________________ Date ___________________ Per ____ 5 – 1 Section Review1. 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? 4
  • 5 – 2 Limits to GrowthLimiting Factor – _______________________________________________________________________________________________________________________________Ex.)• A resource base that is limited can also affect the long term survival of a speciesDensity – 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 populationEx.)• In response to such factors, many species show a characteristic crash in population size 5
  • • 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 populationsName ___________________________________ Date ___________________ Per ____ 5 – 2 Section Review1. 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. 6
  • 5 – 3 Human Population GrowthHistorical 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 lifetimeExponential Human Growth• The following factors have caused a rapid increase in population growth• •• •• ••Patterns of Population GrowthQ: Why can’t the human population keep growing exponentially forever? 7
  • 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 slowlyThe Demographic TransitionAge Structure• Population growth depends, in part on how many people of different ages make up a given populationage-structure diagrams - ____________________________________________________________________________________________________________________________________________________________________________________________________ 8
  • Future Population Growth World Population: 1950 - 2050Year Average Annual Population Growth Rate (%) 1.47 2,555,360,9721950 1.33 3,039,669,3301960 2.19 3,136,556,0921962 2.19 3,206,072,2861963 2.071970 3,708,067,105 1.691980 4,454,607,332 1.58 5,275,407,7891990 9
  • 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 2050Name ___________________________________ Date ___________________ Per ____ 5 – 3 Section Review1. 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? 10
  • 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? 11