The Web of Life

An Investigation Into Energy Transfer

High School Biology I

Designed by Michael Kavur

Introduction | Task | Sources | Process | Guidance | Conclusion

Introduction

All living organisms need energy to survive. Some organisms get their energy from the sun, some get energy from plants. Some organisms eat those who eat plants, while others eat those that eat the plant eaters. This complex mesh of one organism eating another is called the ecological food chain. This web quest activity will explore the dynamics of energy transfer from one organism to another.

Task

This project fulfills Tennessee State Board of Education Standards 2.3, 2.4, 2.5.

1. Students will identify producers, consumers, and decomposers in a food chain.

2. Students will create their own food web using a internet-based program.

3. Students will define primary producer, primary consumer, secondary consumer, and tertiary consumer and give an example of each.

4. Students will examine energy flow through the trophic levels of an food chain.

5. Students will examine the processes involved in biological magnification. 

Sources

Bulaevsky, J.  (2001). Educational java programs. Retrieved April 5, 2004, from  http://www.arcytech.org/java/java.shtml

City & County of San Francisco. (2004). San Francisco government. Retrieved April 5, 2004, from     www.ci.sf.ca.us/sfenvironment/aboutus/school/fact_sheets/d2.pdf

Meng, A., & Meng, H. (2002). Parenting the next generation. Retrieved April 5, 2004, from http://www.vtaide.com/png/foodchains.htm

Kubicheck, J. (1998). Producers, consumers, and decomposers. Retrieved April 5, 2004, from http://www.s-hamilton.k12.ia.us/BiologyHomepage/angiemonthei/producer.htm

Tennessee State Board of Eduction. (2001). Biology I science curriculum standards. Retrieved April 5, 2004, from http://www.state.tn.us/education/ci/cistandards2001/sci/ciscibiology1.htm

The Barn Owl Trust. (2004). Food web. Retrieved April 5, 2004, from http://www.barnowltrust.org.uk/foodweb.html

University of Winnipeg. (2001). Slide 34 of 39. Retrieved April 5, 2004, from http://io.uwinnipeg.ca/~simmons/Chap5498/sld034.htm

Wright, M. (2002) Welcome: A plea for environmental awareness. Retrieved April 5, 2004, from http://trackstar.hprtec.org/main/track_frames.php3?track_id=146169&nocache=542423546

Process

Ecosystems

Ecosystems are self-contained regions that include both living and nonliving factors. For example, a lake, its surrounding forest, the atmosphere above it, and all the organisms living and feeding off the lake would be considered an ecosystem. All members of an ecosystem are, to some degree, dependent on each other. The three categories that all members in an ecosystem fall under are producers (autotrophs), consumers (heterotrophs), and decomposers. Click on the link to learn more about them.

Now that you’ve learned about the main parts of a food chain, determine which of the pictures below is a producer? consumer? decomposer?

  

The Food Chain

The connection between producers, consumers, and decomposers can be illustrated using a food web. To see an example of a food web, visit http://www.vtaide.com/png/foodchains.htm. Once you finish reading the page, click on creating a possible food web and make your own food web. Print a copy of your food web.

There are four trophic (feeding) levels to a food chain: producers, primary consumers, secondary consumers, and tertiary consumers.  

 

 

Click on the ecological pyramid to learn more about the food chain, trophic levels, biomass, and energy flow, then answer the questions below.

 Questions - please type your answers on a word processor

1.    Give an example of an organism found at each trophic level.

2.    Which tropic level posses the highest biomass and greatest numbers?

3.    What happens to the amount of energy available as you move higher up on the pyramid?

4.    Approximately how much energy is lost as you move from one trophic level to another?

5.    Explain why energy gets “lost” as you move up the pyramid.

Toxins In The Food Chain

If a toxin is introduced into an ecosystem, the organisms most likely to be affected are those at the top of the ecological pyramid. Concentration levels of toxins increase at each trophic level, a phenomenon known as biological magnification. When toxic chemicals, such as DDT, are added to an ecosystem, devastating results occur.

 

 

Questions - please type your answers on a word processor

6. Define biological magnification.

7.    How do toxins get transferred from one trophic level to another?

8.    Why are organisms at the top of the food chain most affected by toxins?

9.    Give an example of an animal affected by DDT. What are the symptoms?

Guidance

Reflection

Purpose: The purpose of this product is to teach high school biology students about ecological food chains using the internet as a primary resource. Students will learn the content required of them, as well as develop internet inquiry skills.

Preceding and Ensuing Events of Instruction: The topic presented in this activity are introductory to ecology and do not require previous ecology knowledge. Students need to have a basic understanding of scientific principals and biological concepts. Topics of ensuing instruction should include symbiotic relationships, population ecology, ecological succession, etc.

Improvements on Learning: This web-based activity provides students with the opportunity to use electronic resources for learning. The web-based approach to learning allows students to explore an endless variety of information, far beyond that which the regular classroom can offer.

Improvements & Expansions: This activity could be expanded by integrating related ecological topics into the activity. Since this is a web-based activity, integration can easily be accomplished. This product could be improved if links were provided for a larger variety of related topics.

Conclusion

This activity focused on three major topics related to food chains. The beginning of the activity opened with a  definition of an ecosystem. Students were to look up the definition of producers, consumers, and decomposers. After they did this, they were asked to identify the photos of each. Students then were directed to a web page that allowed them to create their own food web. Students were required to make a food web of their own and print out a copy of it. Students then were redirected to another web site that discussed trophic levels, followed by five questions related to energy transfer. The last activity included a picture of the process of biological magnification with a link to a web site that explained the process. Four questions followed this section. Students are to hand in a copy of their food web, and a word-processed document with answers to all nine questions.

Answer Key:

1. Grass, Mice, Snake, Hawk

2. 1st trophic level

3. Less energy available the higher up the pyramid

4. 10%

5. Energy lost because not all organisms are eaten, those that are eaten are not completely eaten, and energy is lost in respiration growth.

6. Toxic substances cannot be broken down and are stored in the fat. Biological magnification occurs when the concentration of toxic substances increases as you move along the food chain due to predation.

7. Toxins are transferred across trophic levels when predation takes place.

8. Organisms at the top of the food chain are most affected because their food comes from a higher trophic level animals with higher concentrations of toxins.

9. The Osprey. Thin egg shells.

 

 

 

 

THE END