Essential Idea:  Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat.

• Outline answer to each objective statement for topic 4.2 (coming soon)
• Quizlet study set for this topic

At SHS, Topic 4.2 is taught in the following class unit(s):​​​

• ​​Energy Flow through Ecosystem (unit 25)

4.2.U1  Most ecosystems rely on a supply of energy from sunlight.

• State how energy in carbon compounds enters most biological communities.
• List three groups of autotrophs.

4.2.U2  Light energy is converted to chemical energy in carbon compounds by photosynthesis.

• Outline how light energy is converted to chemical energy.​

4.2.U3  Chemical energy in carbon compounds flows through food chains by means of feeding.

• Define food chain and food web.
• State the meaning of the arrow in a food web or chain.
• Draw a food chain, labeling the producer, primary consumer, secondary consumer and tertiary consumer.

4.2.U4  Energy released from carbon compounds by respiration is used in living organisms and converted to heat.

• List three reasons why living organisms need energy for cell activities.
• State the function of ATP.
• Outline how ATP is formed, referencing exothermic and endothermic reactions.
• Outline the reason why respiration releases heat.

4.2.U5  Living organisms cannot convert heat to other forms of energy.

• Draw a flow chart to illustrate the energy conversions performed by living organisms.

4.2.U6  Heat is lost from ecosystems.

• State the reason why heat created by living organisms is eventually lost from the ecosystem.

4.2.U7  Energy losses between trophic levels restrict the length of food chains and the biomass of higher trophic levels.

• Define biomass.
• Define trophic level.
• State the unit used for communicating the energy in each trophic level of a food chain.
• Outline three reasons why the amount of energy decreases at higher trophic levels.
• State the average amount of energy passed through each trophic level of a food chain.

4.2.S1  Quantitative representations of energy flow using pyramids of energy.

• Describe the shape and units of a pyramid of energy.
• Draw a pyramid of energy given data for an ecosystem.​

4.2.NOS  Use theories to explain natural phenomena- the concepts of energy flow explains the limited length of food chains.

• Explain why there is a limited number of organisms in a food chain.​

In the News:

• She Finds Clues to Future Sustainability in Old Food Webs (2019-03-21)
  
• Who Wants to Eat a Gooey Jellyfish? Pretty Much Everyone in the Ocean (2018-09-28)
• What Eats What: A Landlubber’s Guide to Deep Sea Dining (2017-12-19)
• ​Unique field survey yields first big-picture view of deep-sea food webs (2017-12-06)
• ​​Fish live beneath Antarctica (2015-01-21)
• ​​Atop Food Chain, Ospreys Ingest Many Poisons, Revealing Environmental Dangers (2014-08-26)
• Snack attack: Bears munch on ants and help plants grow (2015-01-22)
• Revealed: The Ocean's Tiniest Life At The Bottom Of The Food Chain (2015-05-22)
• The secret lives of jellyfish (2016-03-22)
• The Freaky Food Chain Behind Your Lobster Dinner (2016-12-08)
• Tiny Forage Fish At Bottom Of Marine Food Web Get New Protections (2016-04-07)
• Loss of 350 miles of Great Plains streams causing changes in aquatic food web (2017-08-02)

I give many of my IB Biology resources away, for the benefit of students and teachers around the world.  If you've found the materials helpful, please consider making a contribution of any amount to this Earthwatch Expedition Fund. 

​Did I forget something?  Know of a mistake? Have a suggestion?  Let me know by emailing me here.  Cheers!

Before using any of the files available on this site, please familiarize yourself with the Creative Commons Attribution License.  ​​It prohibits the use of any material on this site for commercial  purposes of any kind.  ​