Topic 4.2: Energy Flow

Essential Idea:  Ecosystems require a continuous supply of energy to fuel life processes and to replace energy lost as heat.
At SHS, Topic 4.2 is taught in the following class unit(s):

Statements & Objectives:

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.​
"When we try to pick out anything by itself, we find it hitched to everything else in the Universe." 
 John Muir,   1911