Framework

Concept Framework^? for DQCs

PRINCIPLES^?

All of the topics within these DQCs deal with two overarching principles, conservation of energy^? and conservation of matter^?.   We want students to use “principled reasoning” to think about processes^? involved in ecosystem carbon cycling.  By using principled reasoning, students are less likely to form misconceptions, will more easily dispel misconceptions, will be better able to connect the same process across scales, and will be better able to reason about processes when they are presented in novel contexts.

1) Conservation of Matter: Matter can neither be created nor destroyed

- the biosphere is essentially closed with respect to matter

2) Conservation of Energy - Energy can neither be created nor destroyed

- the biosphere is open with respect to energy (sunlight is the ultimate source of energy in the biosphere for most ecosystems, with the exception of some that are based on chemosynthesis, e.g., hydrothermal vents)

- energy and matter are related (energy can flow through ecosystems in conjunction with matter as chemical bond energy)

- with respect to the scale of atoms and above, energy and matter are not interchangeable (energy cannot become matter and matter cannot become energy)

PROCESSES

All of the topics within the DCQs can be reduced to three basic principles: generation^?, transformation^?, and oxidation^? of organic carbon.   In parentheses are typical topics within college Biology curricula that fall under each basic process.  By helping students to categorize specific topics under a more general process, they will be better able to see similarities between topics and make knowledge transfers.

1) Generation of Organic Carbon (photosynthesis, primary production)

2) Transformation of Organic Carbon (building of biomolecules within an organism, consumption of one organism by another, defecation, root exudation, plant secretions)                  

3) Oxidation or Organic Carbon (autotrophic respiration, heterotrophic respiration, decomposition, combustion of fuels, weight loss, greenhouse gas accumulation)

SCALE

Students need to be able to recognize the explicit scale at which a question is being asked and they need to be able to connect processes between scales (e.g. how does is net primary production relate to photosynthesis at the organismal level?) when necessary.  Note that pretty much every question requires students to make some connection between higher scales and atomic-molecular processes.

1) Atomic-Molecular/Cellular

2) Macroscopic/Organismal 

3) Ecosystem

4) Human Influenced Systems

FORMS AND REPRESENTATIONS^?

Within a typical biology curricula are standard forms and representations that help biologists reason about ecosystem carbon cycling.           

1) Matter (atoms, molecules, cells, tissues, organs, whole organisms, biomass of an entire trophic level, gasses, liquids, fossil fuels, food, nutrients)

2) Movement of matter at all scales (e.g. Food chain/web diagrams, box and arrow diagrams, chemical equations)

3) Energy (sunlight, chemical potential energy within an organism’s biomolecules, chemical potential energy of fossil fuels, electrical, kinetic, etc.)

4) Flow of Energy at all scales (e.g. Food chain/web diagrams, box and arrow diagrams)

Content Framework