C4.2  Transfers of Energy and Matter

Theme:  Interaction and Interdependence

Organisms and the abiotic environment interact during the transfer of chemical energy and matter .

• Energy enters the community through the interaction of producers with sunlight.
• Energy moves through the community via ingestion, where a consumer interacts with a producer or another consumer. Each interaction results in the transfer of carbon compounds.
• Interactions are never 100% efficient at the transfer of energy. When a consumer interacts with its food, only about 10% of the energy is stored in new biomass. The rest is lost to the environment as heat, an interaction between the organism's metabolism and the surrounding atmosphere. 
  
• Decomposition is the interaction between decomposers and dead organic matter. Saprotrophs secrete digestive enzymes onto the matter (extracellular digestion), breaking down complex molecules into simpler inorganic nutrients.

While energy flows through and leaves ecosystems, matter must be shared in an endless interdependent loop.

• An ecosystem is dependent on a constant external input of energy (typically from the Sun) .
  
• Producers depend on decomposers to return inorganic nutrients (like nitrogen and phosphates) to the soil. Conversely, decomposers depend on producers and consumers for their energy. 
• Life on Earth depends on the fact that the same carbon atoms have been recycled for billions of years.
  
• Autotrophs depend on the CO2 produced by the cellular respiration.
  
• Heterotrophs are dependent on the carbon-fixation performed by producers to provide the chemical energy (glucose) needed for survival.

Guiding Questions:  
Guiding questions help students view the content of the syllabus through the conceptual lenses of both the themes and the levels of biological organization.

• What is the reason matter can be recycled in ecosystems but energy cannot?
• How is the energy that is lost by each group of organisms in an ecosystem replaced?

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​Linking Questions:  
Linking questions strengthen students’ understanding by making connections between topics.  The ideal outcome of the linking questions is networked knowledge.

• How does the transformation of energy from one form to another make biological processes possible?
• What are the direct and indirect consequences of rising carbon dioxide levels in the atmosphere?

Key Terms to Know: 

Aerobic Respiration
Anabolic Reaction
Assimilation
Adenosine Triphosphate (ATP)
Autotroph
Biomass
Biome
Carbon Cycle
Carbon Dioxide
Carbon Fixation
Carbon Flux
Carbon Sink
Carbon Source
Carbon-Compound
Cell-Respiration
Chemical Energy
Chemoautotroph
Closed System
Coal

Combustion
Consumer Food Web
Decomposer
Detritus
Digestion
Ecosystem
Energy
Energy Pyramid
Energy Transfer
Feeding
Food Chain
Heat
Heterotroph
Inorganic
Iron-Oxidizing Bacteria
Keeling Curve
Macromolecule
Matter
Natural Gas

Nucleic Acid
Oil
Open System
Organic Matter
Oxidation Reaction
Peat
Photoautotroph
Photosynthesis
Primary Consumer
Primary Production
Producer
Protein
Scientific Law
Scientific Theory
Secondary Consumer
Secondary Production
Tertiary Consumer
Trophic Level
Water

C4.2.1-- Ecosystems as open systems in which both energy and matter can enter and exit.

• Define ecosystem.
• Compare open and closed systems. 
• State the ecosystems are open systems. ​

​C4.1.2— Sunlight as the principal source of energy that sustains most ecosystems.

• State that sunlight is the primary energy source for most ecosystems. 
• Outline an example of an exception of sunlight as the principal energy source in most ecosystems.

C4.2.3— ​Flow of chemical energy through food chains.

• Define food chain.
• Identify producers and consumers in a food chain. 
• Identify the apex predator in a food chain.
  
• State what is indicated by the arrow in a food chain.

C4.2.4— Construction of food chains and food webs to represent feeding relationships in a community.

• Draw a food chain, labeling the producer, primary consumer, secondary consumer and tertiary consumer.
• State the reason why food webs are better representations of trophic relationships in an ecological community than a food chain.​

​C4.2.5— Supply of energy to decomposers as carbon compounds in organic matter coming from dead organisms.

• Outline the role of decomposers in a food web. 
• List examples of decomposers, including both detritivores and saprotrophs. ​​

​C4.2.6- Autotrophs as organisms that use external energy sources to synthesize carbon compounds from simple inorganic substances.

• Define autotroph.
• Define carbon fixation.
• State the reason why autotrophs must “fix” carbon.
• List the two primary uses of energy in autotrophs.

C4.2.7- Use of light as the external energy source in photoautotrophs and oxidation reactions as the energy source in chemoautotrophs.

• ​Compare the energy sources used by photoautotrophs and chemoautotrophs.
• List examples of photoautotrophs.
• List examples of chemoautotrophs.
• Outline how oxidation reactions serve as a source of energy in iron-oxidizing bacteria.

​C4.2.8- Heterotrophs as organisms that use carbon compounds obtained from other organisms to synthesize the carbon compounds that they require.

• Define heterotroph.
• Outline the functions of digestion, assimilation and synthesis of carbon compounds in heterotrophs.

C4.2.9- Release of energy in both autotrophs and heterotrophs by oxidation of carbon compounds in cell respiration.

• State that both autotrophs and heterotrophs perform cellular respiration to produce ATP.
• Describe cellular respiration as an oxidation reaction.

​C4.2.10- Classification of organisms into trophic levels.

• Define trophic level. 
• Identify the trophic level of an organism in a food chain.
• State that many organisms have a varied diet and occupy different trophic levels in different food chains.

C4.2.11- Construction of energy pyramids.

• State the unit used for communicating the energy in each trophic level of a food chain.
• Describe the shape of a pyramid of energy.
• Draw a pyramid of energy given data for an ecosystem.

​​​C4.2.12- Reductions in energy availability at each successive stage in food chains due to large energy losses between trophic levels.

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

C4.2.13- Heat loss to the environment in both autotrophs and heterotrophs due to conversion of chemical energy to heat in cell respiration.

• Describe the reasons why heat created by living organisms is eventually lost from the ecosystem.

C4.2.14- Restrictions on the number of trophic levels in ecosystems due to energy losses.

• State that at each successive trophic level there are few organisms and less biomass. 
• Explain why there is a limited number of  trophic levels in an ecosystem.

C4.2.15- Primary production as accumulation of carbon compounds in biomass by autotrophs.

• Define biomass.
• Define gross and net primary production. 
• State the unit of primary production. 
• Outline why different biomes will vary in their capacity to accumulate biomass. ​

C4.2.16- Secondary production as accumulation of carbon compounds in biomass by heterotrophs.

• Define secondary production. 
• Explain why secondary production is lower than primary production in an ecosystem. ​

C4.2.17- Constructing carbon cycle diagrams.

• Define sink, pool and flux as related to the carbon cycle. 
• Draw a diagram of the carbon cycle through a terrestrial ecosystem; include processes of diffusion, photosynthesis, feeding and respiration.​

​​​​C4.2.18- Ecosystems as carbon sinks and carbon sources.

• State the conditions under which an ecosystem is a carbon sink. 
• State the conditions under which an ecosystem is a carbon source. 
• Define sequestration in relation to a carbon sink.​

​​​​C4.2.19- Release of carbon dioxide into the atmosphere during combustion of biomass, peat, coal, oil and natural gas.

• Define combustion. 
• State the reactants and products of a combustion reaction. 
• State sources of fuel for a combustion reaction. 
• Outline formation of peat, coal, oil, natural gas and biomass.​

​​​​C4.2.20- Analysis of the Keeling Curve in terms of photosynthesis, respiration and combustion.

• Sketch a graph of the annual fluctuation in atmospheric carbon dioxide concentration.
• Explain the annual fluctuation in atmospheric carbon dioxide concentration in terms of photosynthesis and respiration.
  
• State the long-term trend depicted in the Keeling curve.
• Explain the reason for the long term trend depicted in the Keeling curve.

​​​​C4.2.21- Dependence of aerobic respiration on atmospheric oxygen produced by photosynthesis, and of photosynthesis on atmospheric carbon dioxide produced by respiration.

• State the source of atmospheric oxygen. 
• Explain the interdependence of aerobic respiration and photosynthesis. 
• Outline how the annual flux of CO2 is estimated, including the unit.​

​​​​C4.2.22- Recycling of all chemical elements required by living organisms in ecosystems.  

• State that chemical elements can be recycled but energy can not.
• List elements required by living organisms that must be cycled through ecosystems. 
• Outline the generalized flow of nutrients between the abiotic, autotrophic and heterotrophic components of an ecosystem.
• State the role of decomposers in nutrient cycles. ​