Which among the following is not a functional unit of the ecosystem?

Carbon constitutes . . . . . . of dry weight of organisms and . . . . . . percentage is dissolved in oceans out of total global carbon.

From the above given features,how many are associated with primary succession?
Features:
$1$. Occur on newly cooled lava
$2$. Faster succession
$3$. Progress to mesic condition
$4$. Occurs on flooded land
$5$. Slower succession
$6$. Changes in flora only

Distinguish between:
$(a)$ Upright and inverted pyramid
$(b)$ Food chain and Food web

Differentiate between Production and Decomposition.

Which ecosystem is more stable?