Question

The productivity that accumulates as biomass is:

• A. Gross productivity
• B. Net primary productivity
• C. Gross primary productivity
• D. Net secondary productivity

Answer 1

The correct option is B Net primary productivity

To make calculations of biomass and energy balance in ecosystems, productivity is divided into two main types - Net primary productivity (NPP) and gross primary productivity (GPP). GPP is the rate at which energy is captured or organic matter is synthesised by the producers per unit time and area. A more realistic estimate of the amount of energy that actually seeps into the ecosystem that is the amount available for the heterotrophs is the net primary productivity or NPP. This is a measure of the remaining energy or biomass stored by the producers after meeting the cost of respiration and maintenance for the producers.This relationship between NPP and GPP can be simplified by the following equation: NPP = GPP – R (R = respiration and other losses). Thus the productivity that accumulates as biomass is, what remains after respiratory losses, that is NPP.