Energy flow and nutrient cycling are two important components of an ecosystem. What will be true comparison of the two?

Productivity is the rate of production of biomass expressed in terms of :
i. $(\mathrm{kcal} {\mathrm{m}}^{-3}) {\mathrm{yr}}^{-1}$
ii. $\mathrm{g} {\mathrm{m}}^{-2} {\mathrm{yr}}^{-1}$
iii. $\mathrm{g} {\mathrm{m}}^{-1} {\mathrm{yr}}^{-1}$
iv. $(\mathrm{kcal} {\mathrm{m}}^{-2}) {\mathrm{yr}}^{-1}$

In an ecosystem, the rate of production of organic matter during photosynthesis is called as its:

Net primary productivity is the gross primary productivity minus:

Secondary productivity in an ecosystem can be defined as:

The annual net primary productivity of whole biosphere is approximately: