UNIT ____: Energy Flow through Ecosystems          Name: ________________________

Essential Idea(s):

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

IB Assessment Statements and Class 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.

4.1.U3:  Species have either an autotrophic or heterotrophic method of nutrition.

• Define autotroph and heterotroph.

4.1.NOS: Looking for patterns, trends and discrepancies- plants and algae are mostly autotrophic but some are not.

• State the trend found in the nutritional patterns of plants and algae.
• Describe the discrepancy in the nutritional pattern of parasitic plants and algae.

4.1.U4:  Consumers are heterotrophs that feed on living organisms by ingestion.

• Describe the feeding behaviors of consumers.
• List three example consumer organisms.

4.1.U5:  Detritivores are heterotrophs that obtain organic nutrients from detritus by internal digestion.

• Describe the feeding behaviors of detritivores.
• List two example detritivore organisms.

4.1.U6: Saprotrophs are heterotrophs that obtain organic nutrients from dead organic matter by external digestion.

• Describe the feeding behaviors of saprotrophs.
• List two example saprotroph organisms.

4.1.S1:  Classifying species as autotrophs, consumers, detritivores or saprotrophs from a knowledge of their mode of nutrition.

• Identify the mode of nutrition of an organism.

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

• Define food chain.
• 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.
• Outline the reason why respiration releases heat.

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

• Draw a flowchart 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.NOS:  Use theories to explain natural phenomena- the concept of energy flow explains the limited length of food chains.

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

What is Energy?

Energy Conversions Performed by Living Organisms

The law of conservation of energy states that energy can neither be created nor destroyed - only converted from one form of energy to another. Energy Conversion is defined as the process where there is a change in energy from one form to another

Although there is a trend that plants and algae perform photosynthesis, there is a small number of parasitic plants (i.e. mistletoe) that can take nutrients from a host.  Although, they are capable of photosynthesis and evolved from photosynthetic ancestors.  Because they are unique from the norm these parasitic plants are considered a discrepancy. 

Energy Flow Through Trophic Levels

The trophic level of an organism is the number of steps it is from the start of the chain.

What happens to the 90% of energy that does NOT move between each trophic level?

Food Chains and Food Webs

Arrows show ...

Energy Pyramids

Show the energy of each trophic level in an area in any given time.