The amount of organic matter stored by green plants in a unit time and area is called

Justify the following statement in terms of ecosystem dynamics: "Nature tends to increase the gross primary productivity, while man tends to increase the net primary productivity".

State whether the following statements are True or False:
$I.$ The total organic matter synthesized by the producers in the process of photosynthesis per unit time and area is known as gross primary productivity.
$II.$ Net primary productivity is the weight of the organic matter stored by the producers in a unit area/volume per unit time.

The unit of productivity is $.........$

The total annual productivity of the whole biosphere is:

Assertion : Net primary productivity is gross primary productivity minus respiration.
Reason : Secondary productivity is produced by heterotrophs.