An ecosystem is an interacting system made up of $.......$

Given below are a few statements related to biodiversity. Pick those that correctly describe the concept of biodiversity.
$(i)$ Biodiversity refers to the different species of flora and fauna present in an area.
$(ii)$ Biodiversity refers to only the flora of a given area.
$(iii)$ Biodiversity is greater in a forest.
$(iv)$ Biodiversity refers to the total number of individuals of a particular species living in an area.

$(a)$ What is an ecosystem? List its two main components.
$(b)$ We do not clean ponds or lakes,but an aquarium needs to be cleaned regularly. Explain.

State with reason any two possible consequences of the elimination of decomposers from the Earth.

What are decomposers? What will be the consequence of their absence in an ecosystem?

Which organisms obtain nutrition from the dead bodies of plants and animals?