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Investigation 2 – PreLab









Ecologists study populations of organisms and how those organisms interact with each other and with their physical environment.


This Investigation is designed to help you to answer the following Focus Question:

  • What affects the efficiency of energy transfer within an ecosystem? 

Note: This question is located in your SDR at the beginning and end of the Investigation.


As a class, read the Background(s) in the Investigation. When finished, discuss the following concepts as a class:

  • When a plant absorbs light energy from the Sun, it converts the light energy to chemical energy through photosynthesis.
  • When animals consume plant material, their cells can release the energy in the plant biomass through a process called cellular respiration. The same thing happens when animals consume other animals.
  • The cells then use the energy released through respiration to live.
  • This process is called cellular respiration because cells take in oxygen and release carbon dioxide.
  • The more energy an organism needs and uses to live, the more oxygen it will take in.


These terms should be used, as appropriate, by teachers and students during everyday classroom discourse.

  • ecosystem
  • producers
  • consumers
  • detritivore
  • detritus
  • trophic level
  • biomass
  • Law of Conservation of Energy
  • Law of Conservation of Matter

Note: Definitions of these terms can be found on the Introduction page to the CELL.

Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.


  • As a class, review what was learned in Investigation One.

Note: In Investigation 1, you discovered that the amount of energy in each level of an ecosystem is smaller than the amount of energy in the level below it and this indicates that energy transfer is inefficient. You also discovered that higher levels of an ecosystem have smaller amounts of biomass than the levels below them.

  • As a class, discuss prior knowledge about the reasons why energy transfer may be inefficient.
  • Suggest what may be happening to light energy that is not captured by producers.

Note: Some light energy that is not captured by plants may be absorbed by the ground or water. Additional energy may be reflected off the surface of the ground or water. More energy may be absorbed or reflected by animals. Finally, in urban areas energy may be absorbed or reflected by manmade structures

Eco 2 PreLab

  • Watch the video below. Remember to follow along with your SDR and make any notes that you think might be helpful in the lab.
  • After the video, divide into lab groups to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.

Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.

Note: Homework is posted below the video.


You should review the Investigation and video in preparation for the Lab.