Biotic succession is caused by

In a pond,we see plants which are free-floating; rooted-submerged; rooted-emergent; and rooted with floating leaves. Identify the type of plant for each of the following:

Plant Name	Type
$(1)$ Hydrilla	....................
$(2)$ Typha	....................
$(3)$ Nymphaea	....................
$(4)$ Lemna	....................
$(5)$ Vallisneria	....................

In the following,which of these pairs represents the same ecological group?

Given below is a figure of an ecosystem. Answer the following questions.
$(i)$ What type of ecosystem is shown in the figure?
$(ii)$ Name any plant that is characteristic of such an ecosystem.

$A$ rat feeding upon a potato tuber is a:

If the plant producers die in an ecosystem,then the system is