Autumn.wmf (12088 bytes) Concepts of Biology (BIOL116) - Dr. S.G. Saupe; Biology Department, College of St. Benedict/St. John's University, Collegeville, MN 56321;;

A Study Guide for Populations

Goal of the Unit:
    The goal of this unit it to provide an introduction to the topic of population biology with an emphasis on human population growth.

Specific Learning Objectives:  Upon completing this unit you should be able to:

  1. compare and contrast logistic and exponential growth
  2. describe factors that influence population growth
  3. describe the global state of the human population

  4. describe various parameters that characterize populations (i.e., density, survivorship)

Required ReadingPurves, et al, Chapter 54

Important Terms/Concepts (can you use these conversationally?)

  • ecology

  • biosphere

  • carrying capacity

  • community

  • density dependent

  • density independent

  • ecology

  • ecosystem

  • emigration

  • environmental resistance

  • exponential

  • G = rN

  • G = rN((K-N/K)

  • immigration

  • inflection point

  • interspecific

  • intraspecific

  • J curve

  • logistic

  • logistic


  • mortality

  • mortality

  • natality (births)

  • oikos

  • Population

  • r, N, K

  • S curve

  • sigmoidal curve

  • survivorship

  • ZPG


Some Questions for Thought & Study:

  1. What is ecology and why is it important?

  2. Can you define population, community, ecosystem and biosphere and show the relation between these terms.  How large are these units?

  3. Can you write the equations for logistic and exponential growth.  Explain what each of the terms represent.

  4. What is the population doubling time?

  5. Compare and contrast the logistic and exponential growth curves.  Do you know the phases of the logistic curve?  What is the carrying capacity?

  6. What conditions favor a population crash?  explosion?

  7. Compare and contrast density independent and density dependent factors.  Give examples of each.  How is the population growth equation modified to account for environmental resistance?

  8. What is a survivorship curve?  Draw and label the three types of curves and explain their significance.  Which curve is typical for humans?  animals? plants? the Survivor TV show?

  9. Sketch and describe the population age structure pyramid.  What can we learn from them?  What can you tell about the potential for future growth?

  10. What is meant by population density?  Give some examples of populations that live at high density and low density

  11. How are populations distributed in space?  Identify the three major patterns and give examples of each.  Which is most common?  least common?  explain.

  12. Can you plot an exponential growth curve?  How does this relate to the story of the King and rice?  How would the curve change if the King paid rice every other square?  or if the Courtier removed some rice every day?  or the King paid triple rice for each square?  How much would the King have paid on the 50th day?  How can you figure this out?

  13. Can you plot a logistic curve such as  the yeast data?  

  14. Can the carrying capacity of a population ever change?

  15. Can you answer the questions at the end of the chapter?

ZPG Video Questions:

  1. Approximately what years did you notice a large increase in population growth?  What events were associated with this change?

  2. Did you notice periods of population decline?  When, where and why?
  3. Where does the greatest growth occur?
  4. Are any areas likely to remain relatively unpopulated by the year 2020?  Explain.
  5. What does the drum/heart beat represent?
  6. What growth pattern (logistic vs. exponential) growth pattern would result if the drumbeat frequency was plotted vs. time? How would the drumbeat  have differed if the other growth curve were plotted?
  7. Where were the greatest human populations at the beginning of the video?

A Graphing Exercise:
    The following data are taken from Garrett Hardin (1987).

Year Population (billions)
1650 0.5
1823 1.0
1929 2.0
1961 3.0
1974 4.0
1987 5.0
  1. Graph these data (population vs. year)
  2. In what year do you predict the population to reach 6.0 billion?  In what year did the population actually reach 6.0 billion (you'll have to look this up).
  3. At our current rate of growth, how many years wlil it take for our population to double (i.e., to reach 10 billion)?
  4. In 1929, what was the doubling rate?

More Fun:

  1. The current world population is about 6 billion and the US population is approximately 280 million.  To appreciate the magnitude of difference between a million and a billion - calculate how old you would be if you were a million seconds old?  a billion seconds?
  2. How many great-great grandchildren will you have if you and all of your descendents have 1 child.  2 children?  3? 4? 5?
  3. Complete the questions on the Population Exercises Sheet
| Top| SGS Home | CSB/SJU Home | Biology Dept | Biol116  Section Home Page | Concepts Home Page | Disclaimer |

Last updated: April 01, 2004        � Copyright by SG Saupe