A hectare of wheat fixes 32,000 kg of carbon per year through photosynthesis and uses 7,000 kg of carbon per year for cellular respiration. The net primary productivity of the wheat field is therefore ________ kg of carbon/hectare/year.

Question

Fill in the blank(s) with the appropriate word(s).

Answer 1

25000

Clarify Question


• What is the key concept addressed by the question?
     o This question addresses net primary production.
• What type of thinking is required?
     o This question is asking you to take what you already know and apply it to this unfamiliar situation.


Gather Content


• What do you already know about net primary production?
     o To measure ecosystem biomass production, we are primarily interested in plants, algae, or cyanobacteria.
     o Because these photosynthetic organisms represent the first, or primary, trophic level, their production is called gross primary production (GPP). Gross primary production is equivalent to the carbon fixed during photosynthesis.
     o Net primary production (NPP) is GPP minus the energy used during cellular respiration (R) of photosynthetic organisms.
     o NPP = GPP - R
     o NPP is thus the amount of energy available to primary consumers. Unless otherwise noted, the term primary production refers to NPP.


Choose Answer


• Given what you now know, what information and/or problem-solving approach is most likely to produce the correct answer?
     o NPP = GPP - R
     o So in this case, NPP = 32,000 - 7,000 kg carbon / hectare / year = 25,000kg carbon / hectare / year.


Reflect on Process


• Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
     o The question required you to take what you already know and apply it to this unfamiliar situation.
     o Did you recognize that you must subtract the respiration cost from the gross primary productivity to find the net primary productivity?