Model Ecosystems

Lab 4 Worksheet: Model Ecosystems

Student instructions: Follow the step-by-step instructions for this exercise found on the worksheet below and in the virtual lab and record your answers in the spaces below. Submit this completed document by the assignment due date found in the Syllabus.

Please make sure that your answers are typed in RED.

Please type your Name and Student ID Number here:

Directions

1. Open the Virtual Lab titled “Model Ecosystems”.

2. Please make sure you have read through all of the information in the “Question” and “Field Guide” areas.

3. In this exercise, you will examine several model ecosystems and their characteristic plant and animal species. To begin, read the information in the “Field Guide” to learn more about the organization of five selected ecosystems.

4. If you come upon terms that are unfamiliar to you, please refer to your textbook for further explanation or search the word here: http://encarta.msn.com/encnet/features/dictionary/dictionaryhome.aspx

5. You are now ready to begin the activity. Start by selecting the ecosystem type that you would like to model from the pull down menu at the top of the screen.

6. Click and drag the various organisms to their correct locations within the different trophic levels of the pyramid. Once you have moved all of the organisms click the “Check” button and fix any incorrect choices if necessary.

7. List each of the organisms (by name) at each trophic level under the “Organisms Present:” area on Table 1.

8. Clicking on the “Pyramid of Numbers” will show the number of organisms at each trophic level within this type of ecosystem. Fill in this information from the pyramid on Table I below under the “Numbers:” area.

9. Clicking on the “Pyramid of Energy” will reveal how much energy is available at each trophic level. Fill in this information from the pyramid on Table 1 below under the “Energy:” area.

10. You must take one last step in the investigation of this ecosystem. It is important to determine the amount of energy that is transferred from one trophic level to the next. This is called the “Energy Conversion Efficiency” (E.C.E.), and this ratio is determined by taking the energy value from the trophic level you are calculating the E.C.E. for and dividing it by the energy value of the level below it. Please do these calculations as directed below and input the data in Table I below.

11. When you are completely finished analyzing the ecosystem, you can click the “Reset” button and select another type of ecosystem from the pull down menu. Follow the directions above to investigate this ecosystem and the three that remain.

12. Answer Lab Questions 1-17 below.

Table 1

To complete the Table below, students should complete the following 4 steps.

1. List the organisms present in each ecosystem (i.e. hawks, snakes, etc.) under “Organisms Present:”.

2. List the total number of organisms present at each trophic level in each
Ecosystem under “Numbers:”.

3. List the total energy at each trophic level in each ecosystem under “Energy:”.

4. Calculate and list the E.C.E. The E.C.E. can be calculated by taking the energy value from the trophic level you are calculating the E.C.E. for and dividing it by the energy value of the level below it.

Example: First Order Heterotrophs / Producers = ECE for First Order Heterotrophs

*Round all E.C.E. values to the 3nd (thousandths) decimal place.

Ecosystem Type Producers First Order Heterotrophs Second Order Heterotrophs Third Order Heterotrophs
Deciduous Forest Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.:
Hot Desert Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.:
Grassland Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.:
Antarctic Ocean Shore Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.:
Freshwater Lake Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.: Organisms present:

Numbers:
Energy:
E.C.E.:

Lab Questions:

1. The ultimate source of energy for most ecosystems is:
a. Carbon
b. Oxygen
c. Sunlight
d. Water

2. Organisms that directly use energy from the sun to make their own food are called:
a. Autotrophs
b. Hetertrophs
c. Carnivores
d. Decomposers

3. Which of the following illustrates the correct ordering of trophic levels?
a. Decomposerscarnivoresautotrophsherbivores
b. Herbivoresautotrophscarnivoresdecomposers
c. Autotrophsherbivorescarnivoresdecomposers
d. None of the above

4. Within an ecosystem:
a. Energy flows in one direction only and nutrients are recycled
b. Energy is recycled and nutrients flow in one direction only
c. Energy and nutrients flow in one direction only
d. Energy and nutrients are both recycled

5. The efficiency of energy transfer from a lower trophic level to the next highest level is roughly:
a. 1%
b. 5%
c. 10%
d. 50%
e. 80%

6. In aquatic ecosystems, biomass is least at which trophic level?
a. Autotrophs
b. Herbivores
c. Carnivores

7. You are in an area where there are squid, seals and penguins. You are most likely in which ecosystem?
a. Deciduous forest
b. Hot Desert
c. Antarctic Ocean Shore
d. Grassland

8. You find yourself in an area where there are snakes, hawks and coyotes. Based upon these animal populations, you are most likely in which ecosystem?
a. Deciduous forest
b. Hot Desert
c. Grassland
d. You cannot tell from this information

9. You are in an area where the ground is littered with what appear to be dry, dead leaves. You are most likely in which ecosystem?
a. Deciduous forest
b. Hot Desert
c. Grassland
d. You cannot tell from this information

10. This zone has the greatest concentration of plankton in a freshwater lake ecosystem:
a. Profundal
b. Littoral
c. Limnetic

11. Suggest reasons why the information represented in the pyramid of numbers of animals of one of the ecosystems you studied may not truly represent that ecosystem.

12. According to your data, what is the ratio of third-order consumers to producers? Explain your answer.

13. Compare and contrast two of the ecosystems you studied. How is the energy conversion efficiency similar or different?

14. Does the population size increase or decrease at higher trophic levels in the pyramid of numbers of an ecosystem consisting of a tree, insects (that are herbivores) and birds feeding on the insects? Explain your answer.

15. What might happen to an ecological pyramid of numbers in a forest ecosystem if most of the deer were killed due to hunting by people and disease?

16. What would happen to an ecosystem if the decomposers disappeared?

17. Could there be a food chain without herbivores and carnivores?