Topic 1.2 Energy Flow

Enduring Understanding:  Energy and nutrients move within and between biotic and abiotic components of ecosystems via physical, chemical and biological processes. Rally Table!

Rally Table  Teacher reads question and provides think time  Students think about the question, write an answer, then pass their paper clockwise to the next person at their table.  Each student writes their answer on the paper in front of them and passes the paper until their own paper comes back to them.

Question One:  Name one example of a physical process involved in energy flow.

Question Two:  Name one example of a chemical process involved in energy flow.

Question Three:  Name one example of a biological process involved in energy flow.

 Producers – autotrophs  Plants & Photosynthetic bacteria What are the various levels of a food web? Define producer

What are the various levels of a food web?  Consumers – heterotrophs  Herbivores – eat only producers Describe how consumers obtain energy and nutrients

What are the various levels of a food web?  Consumers – heterotrophs  Carnivores – eat only herbivores Describe how consumers obtain energy and nutrients

What are the various levels of a food web?  Consumers – heterotrophs  Omnivores – eat either producers or herbivores Describe how consumers obtain energy and nutrients

What are the various levels of a food web?  Consumers – heterotrophs  Saprotrophs – fungi that absorb nutrients from surrounding environment Describe how consumers obtain energy and nutrients

What are the various levels of a food web?  Detritivores & Decomposers  Detritivores eat nonliving plant and animal remains  Scavengers  Beetles  Worms Describe how consumers obtain energy and nutrients

What are the various levels of a food web?  Detritivores & Decomposers  Decomposers complete the food chain  Fungi  Bacteria  Return nutrients to soil or oceans for use by autotrophs Describe how consumers obtain energy and nutrients

Marine Food Web  In a food web, arrows show the direction of energy flow.  For example: krill eats the phytoplankton, but the energy flows from the phytoplankton to the krill. Students will describe the energy pathways through the different trophic levels of a food web or energy pyramid.

 On average about 10 percent of net energy production at one trophic level is passed on to the next level. How does energy flow through ecosystems? Trace the flow of energy through a living system.

3 Reasons for decrease in available energy  Energy is “used up” for daily life activities.  Not all organisms that die are eaten by animals in the next trophic level.  Not all parts of an organism are eaten and digested for energy. Trace the flow of energy through a living system.

An example of an energy pyramid: Trace the flow of energy through a living system.

Energy Pyramid  An energy pyramid is a graphical model of energy flow in a community.  The different levels represent different groups of organisms that might compose a food chain. Trace the flow of energy through a living system.

Energy Pyramid from the bottom up:  Producers — bring energy from nonliving sources into the community

Energy Pyramid from the bottom up:  Primary consumers — eat the producers, which makes them herbivores in most communities

Energy Pyramid from the bottom up:  Secondary consumers — eat the primary consumers, which makes them carnivores

Energy Pyramid from the bottom up:  Tertiary consumers — eat the secondary consumers

Energy Pyramid from the bottom up:  Quaternary consumers — eat the tertiary consumers

Energy Pyramid  In some food chains, there is a fourth consumer level, and rarely, a fifth.  Have you ever wondered why there are limits to the lengths of food chains?

10% Rule Explain how the amount of energy available at each trophic level in an energy pyramid limits the number of organisms that each trophic level can support.

An Example of a Biomass Pyramid

Biomass Pyramid  In a “biomass pyramid“, the comparative masses of consumers and food can be represented simultaneously.

Biomass Pyramid  Similar to the energy pyramid, the base (producers)is much broader than the top levels.  Quaternary consumers comprise only 1/10,000 th of the biomass in this ecosystem.

Biomass Pyramid  This is the reason that there are limits to the number of trophic levels possible in an ecosystem.

Nutrient Cycling vs. Energy Flow  Energy flow is unidirectional: approximately 10% of the available energy is passed on to the next trophic level.

Nutrient Cycling vs. Energy Flow  Nutrients cycle through the food web.  From producers to consumers to decomposers, then back to producers.

Citations   mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Saprotrophs.html mnb.ca/mycologywebpages/NaturalHistoryOfFungi/Saprotrophs.html   web/?ar_a=1 web/?ar_a=1      olhs.cksd.wednet.edu/ 