SCI 225 National Louis University Ecology Lab Report

INSTRUCTIONS

Lab Instructions:

Part 1: Answer the following questions.  

1. What is the origin of most of the energy within an ecosystem?
2. Describe the major difference between autotrophs and      heterotrophs.
3. Describe the major difference between herbivores and carnivores.
4. Explain the difference between the pyramid of energy and the      pyramid of biomass.  Include the      definitions of energy and biomass in your response.

Part 2: Online, do some research – look up a “trophic pyramid” and choose a specific image.  Then really consider the ecosystem that the image is representative of (e.g., is it a desert, tropical rainforest, grassland, marine, etc.).  Do some research on the organisms and really examine the trophic pyramid picture.  Provide a link to it in your word doc (or copy it in APA format).

See if you can find information on the total number of organisms at each trophic level.

Now do the same for a second (different) ecosystem.

What is the name/type of your first ecosystem? _________________ 

What is the name/type of your second ecosystem? ________________ 

Complete the Data Table below for both ecosystems, (i.e., complete the % Energy Conversion Efficiency).

Energy Conversion Efficiency % = [(energy of the higher trophic level) ÷ (energy of the lower trophic level)] × 100

You can round to the nearest tenth place.

Table 1: Energy Conversion Efficiency of two ecosystems

Energy   Conversion Efficiencies   (in %)

Your Ecosystem (1)

Your Ecosystem (2)

Second   Order Heterotrophs to Third Order Heterotrophs

First   Order Heterotrophs to Second Order Heterotrophs

Producers   to First Order Heterotrophs

Average   Energy Conversion Efficiency

Part 3: Analyze your data table and answer the following questions.

1. Compare and contrast the ecosystems you studied in this lab.      Explain how the energy conversion efficiencies from Table 1 are similar or      different to each other.
2. Predict 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.
3. What would happen to an ecosystem if the decomposers      disappeared?  Explain your answer.
4. Could there be a food chain without herbivores?  Explain your answer.
5. Why do you think there are no fourth order heterotrophs in these      model ecosystems?  Explain how the      pyramid of energy and energy conversion efficiency is related to your      answer.