Which of the following is the unit of productivity of an Ecosystem?

Question

Question

This question was previously asked in

NEET 2025 Official Paper (Held On: 04 May, 2025)

Answer 1

The correct answer is (KCal m–2)yr–1

Explanation:

Productivity

The amount of biomass or organic matter produced per unit area over a time period by plants, by the process of photosynthesis is called primary production.
It is expressed in units of weight (g per m2) or energy (Kcal per m2).
The rate of biomass production is called productivity and it is expressed as g m-2 yr-1 or (Kcal m-2) yr-1.

Primary productivity is further divided into two categories:

Gross Primary Productivity (GPP): The rate of production of organic matter during photosynthesis is called gross primary productivity. A large amount of GPP is lost by plants during respiration.
Net Primary Productivity (NPP): It is defined as the difference between gross primary productivity and the respiration losses (R) by plants.
- NPP = GPP - R;
- It is the measure of net available biomass for heterotrophs (herbivores and decomposers).
- Since net primary productivity is obtained after subtracting respiration losses from gross primary productivity; it is always less than gross primary productivity.