Question

zone,is the deep water zone containing only heterotrophs

Answer 1

no deep water zone not containing only heterotrophs

Answer 2

No, the deep water zone not only contains the heterotrophs becuase much more organism will also be found inside the deep water zone along with the organism like heterotroph.

However, in general, heterotrophs has the ability to mineralize all the essential elements which are very important for plant survival.

Also, all the prokaryotes are heterotrophic in nature.