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;;


Energy - Study Guide

  Purves et al.  Chapter 55 

Goal and Objectives:  The major goal of this unit is to provide you with an understanding of the source, nature and mechanism of the movement of energy and nutrients in an ecosystem.  Specifically, upon completion of this unit you should be able to:

  1. outline the basic processes of photosynthesis and respiration

  2. describe the basic model for energy flow and its biological consequences

Important Terms/Concepts: (be able to use conversationally)    

  • 1st & 2nd Laws of Thermodynamics

  • autotroph              

  • carbon fixation

  • carnivore

  • consumers

  • decomposer

  • detritivore

  • detritus

  • food chain    

  • food web  

  • herbivore

  • heterotroph

  • photosynthesis

  • predator  

  • prey

  • producers

  • trophic level

Questions for Thought and Study:

  1. What is the 10% Rule of Thumb?  Why is it called a rule and not a law?

  2. Energy is lost in the transfer between each trophic level.  Where does that energy go?

  3. Write the equation for photosynthesis.  Write the equation for respiration.  What is the function of each process?  Where do they occur in the cell?  In what type of organisms?  Could life exist without one or the other?

  4. Compare and contrast food chains and food webs.  Which is more stable and why?  Give an example of each.  

  5. Can you use these terms? producer, consumer, primary consumer, secondary consumer, tertiary consumer, herbivore carnivore, primary carnivore, secondary carnivore, detritivore, decomposer.  Can you give examples of each?

  6. State the first and second laws of thermodynamics.  Relate their importance to energy flow.

  7. In what form does energy flow through food webs? 

  8. Explain why energy flow is diagrammed as a pyramid.  Identify other aspects of ecosystems that can be described using the pyramid model. Can any of  these pyramids be inverted?

  9. If the producers have 1000 units of energy, calculate the approx. amount of  energy in a tertiary consumer.

  10. Explain why most food chains are rarely more than 3-5 links.

  11. Explain why whales, hippos and apatosaurs are big.  

  12. Explain why there are few carnivores larger than the "cats".

  13. Some biologists consider it doubtful that T. rex was an active predator.   Why? 

  14. What is the principle of food size?

  15. Which is energetically more efficient: a weasel or mouse?  Explain.

  16. Human cultural evolution can be related to the energy pyramid.  Explain.

  17. What are some future predictions concerning our energy future?  Do you agree or disagree with these?

  18. Defend or attack the statement:  In the future, humans will probably eat less meat.

  19. What is biological magnification?

  20. Explain why DDT decimated the populations of ospreys and other birds of prey even though it was sprayed in the environment in relatively low, non-toxic doses.

  21. Explain why it is true that conditions that control the growth of producers ultimately control all the individuals in the ecosystem as well.

  22. Why should you not eat too many, say lake trout, from Lake Superior?

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Last updated: April 22, 2004        � Copyright by SG Saupe