Question

The biomass available for consumption by herbivores and decomposers is called -

• A. Net primary productivity
• B. Primary production
• C. Standing crop biomass
• D. Gross primary productivity

Answer 1

The correct option is A Net primary productivity

The amount of biomass or organic matter produced by plants during photosynthesis per unit area is defined as primary production. It is expressed either in units of weight i.e $g{m}^{-2}$ or energy i.e $kcal/m^2$. The rate at which this biomass accumulates is defined as productivity and is expressed as $g{m}^{-2}/yr$ or $kcal/m^{-2}/yr$.
Productivity are of two types: 1. Gross primary productivity or GPP- is the rate at which energy is captured or organic matter synthesised by the producers per unit area and time. It’s equivalent to total photosynthesis and indicates the capacity of producers to assimilate solar energy into living matter. 2. Net primary productivity or NPP- is the amount of biomass available for the heterotrophs (including herbivores, carnivores, decomposers) it is a measure of the remaining energy or biomass left after meeting the cost of respiration and maintenance of the producers.This relationship between NPP and GPP can be simplified by the following equation: NPP = GPP - R (R = respiration and other losses).
Standing crop biomass - is the total weight of the organisms which are in present in a particular location at a particular time. It is usually expressed as grams of organic matter per square meter $\left(g/m^2\right)$.