Which term equals gross primary production minus respiration by producers?

• A. Gross Primary Production
• B. Net Primary Production
• C. Productivity
• D. Net Primary Productivity

Answer: (B)

Net primary production measures the energy stored as plant biomass after plants meet their own metabolic needs. Think of gross primary production as the total energy plants capture via photosynthesis. A chunk of that energy is then spent on respiration to fuel growth, maintenance, and other cellular processes. What remains—the energy that actually goes into building new plant material—is net primary production. This value represents how much biomass becomes available to herbivores and enters the rest of the food web, and it’s often expressed as biomass per area per time (for example, grams of carbon per square meter per year). Net primary production and net primary productivity refer to the same concept.