$A$ : Estuary constitutes one of the most productive ecosystem.
$R$ : It represents transition zone between two populations of a species.

Carrying capacity of earth is

Name the term used to describe a single dominant species that dictates community structure

Deep black soil is considered to be highly productive due to high proportion of

$A$ : Some organisms can maintain internal homeostasis by means of physiological processes and are called
'Regulators'.
$R$ : 'Regulators' can maintain internal homeostasis only upto a limit of stressful conditions.