How many sentence are correct?
$(1)$ The trophic levels in $GFC$ are unlimited
$(2)$ Organisms at each trophic level depend on those at the higher trophic level for their energy demands.
$(3)$ Plants capture only $2 -10$ percent of $PAR$.
$(4)$ All organisms are dependent for their food on producers, either directly or indirectly.
$3$
$2$
$4$
$1$
The planktonic forms are
The number of trophic levels in an ecosystem are limited. Comment.
$A$ : In secondary productivity, no new organic matter is formed.
$R$ : It is only utilisation of part of food manufactured by primary producers in building of consumer biomass.
First link in any food chain is a green plant because
If forest area is reduced to half, which one of the following will be a long term effect