To make the study of global ecosystem easier,it is broadly divided into how many basic categories?

$A$ plant being eaten by a herbivore,which in turn is eaten by a carnivore,constitutes a:

The last stabilized community in a plant succession is known as:

Distinguish between primary succession and secondary succession based on the following examples:
$I-$ Abandoned farmland
$II-$ Burned or cut forests
$III-$ Newly cooled lava
$IV -$ Bare rock
$V -$ Flooded lands
$VI -$ Newly created pond or reservoir
Identify the correct grouping for primary succession and secondary succession respectively.

Which of the following levels is conceptual in terms of size?

Define the following terms:
$(i)$ Sere
$(ii)$ Standing state