Statement I: Productivity, decomposition, energy flow, and nutrient cycling are the four important components of an ecosystem.
Statement II: Primary productivity is the rate of capture of solar energy or biomass production of the producers.
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Both Statements I and II are correct.
An ecosystem works as a unit through four functional aspects: productivity, decomposition, energy flow and nutrient cycling. Of these, primary productivity measures how fast producers capture solar energy and build biomass.
Statement I: Productivity, decomposition, energy flow, and nutrient cycling are the four important components of an ecosystem. — True. NCERT lists these four as the important components through which an ecosystem functions.
Statement II: Primary productivity is the rate of capture of solar energy or biomass production of the producers. — True. Primary productivity is the rate at which producers capture solar energy, seen as the rate of biomass production.
Note: Both lines come almost word for word from the chapter Summary. Many students close the book before the Summary; examiners do not.
NCERT Extract:
Summary – “… Based on source of nutrition every organism occupies a place in an ecosystem. Productivity, decomposition, energy flow, and nutrient cycling are the four important components of an ecosystem. Primary productivity is the rate of capture of solar energy or biomass production of the producers. It is divided into two types: gross primary productivity (GPP) and net primary productivity (NPP).”