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Investigation 1 – PreLab









We all depend on healthy ecosystems for our survival. Healthy ecosystems perform essential services that we depend on, including clean air, clean water, food, clothing, fuel, and lumber products. In addition, healthy ecosystems regulate floodwaters and keep lands fertile and crops pollinated.


Marine biologists research how ocean acidification is affecting marine organisms. They also focus on migration patterns of marine mammals, photosynthesis of underwater plant life, or methods to promote coral reef protection.


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

  • How does energy move through an ecosystem?
  • What affects the amount of energy in an ecosystem?

Note: These questions are 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:

  • The organisms in an ecosystem can be divided into two main groups: producers and consumers.
  • Producers are autotrophs, a term which means they make their own food.
  • Consumers are heterotrophs, which means they must obtain food by consuming producers or other consumers.
  • Depending on the ecosystem, there may be a different number of levels of consumers in the ecosystem.  
  • In general, the consumers in one level consume organisms from the level below. 
  • Biomass is the term scientists use to refer to the amount of dry matter in an ecosystem.
  • Dry matter is the material left after all the water has evaporated from an organism.
  • Biomass is measured in grams of dry matter per square meter (g/m2).
  • Light energy from the Sun enters an ecosystem when plants use it to perform photosynthesis.
  • Photosynthesis converts carbon dioxide and water into chemical energy.
  • The chemical energy is stored as starch or sugar. It is also used to make the structures of the plant.


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.


  • Be able to explain how photosynthesis allows plants to convert light energy into chemical energy for storage.

Note: Photosynthesis captures light energy during the conversion of carbon dioxide and water to glucose, which is stored in the plant as starch. The starch can be broken down to glucose which the plant metabolizes to release energy for growth and life processes during times when the plant is not exposed to light.

  • Ecosystems vary in the types of plants and animals that populate them. However, all ecosystems must have producers and consumers.
  • Can you explain the difference between producers and consumers and why both are necessary in an ecosystem?

Note: Producers are the organisms in an ecosystem that turn light energy into chemical energy that is stored in plant biomass. This chemical energy then enters the consumer levels when producers are consumed by herbivores and progresses up the ecosystem as the different consumer levels eat. Both types of organisms are needed for an ecosystem to be self-sustaining and to keep nutrients cycling through the ecosystem.

  • During this Investigation, we will discuss how energy moves through an ecosystem and explore how energy and biomass are related.
  • Can you predict whether the amount of energy in each ecosystem level is the same?
  • Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful.
  • 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.