BIology Lab

Virtual Lab:

Post-Lab Quiz and Lab Report

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

2. 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.

3. 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 in the laboratory area. Then 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.

Clicking on the “Pyramid of Energy” will reveal how much energy is available at each trophic level. Clicking on the “Pyramid of Numbers” will show the number of organisms at each trophic level within this type of ecosystem. Fill in all of the information from this pyramid on Table I below.

4. 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 a higher trophic level and dividing it by the energy value of the level below it. Please do these calculations as directed and input the data in your “Data Table” and Table I below.

5. When you are completely finished analyzing the ecosystem, you can then 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.

6. Please finish this exercise by opening the “Journal” link at the bottom of the page and answering the questions.

Table I:

Ecosystem Type	Producers	First Order Heterotrophs	Second Order Heterotrophs	Third Order Heterotrophs
Deciduous Forest	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:
Hot Desert	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:
Grassland	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:
Antarctic Ocean Shore	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:
Freshwater Lake	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:	Organisms present: Energy: Numbers: E.C.E.*:

*E.C.E.= energy conversion efficiency ratio

Post-laboratory Questions:

1. The ultimate source of energy for most ecosystems is: C

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

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.

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

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

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.

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?

What would happen to an ecosystem if the decomposers disappeared?

Could there be a food chain without herbivores and carnivores?