Define the following terms:
$(i)$ Saprotrophs
$(ii)$ Trophic level

The transition zone between two ecosystems or vegetational regions is termed as:

An ecosystem can be described as:

Given below is a list of autotrophs and heterotrophs. With your knowledge about food chain,establish various linkages between the organisms on the principle of 'eating and being eaten'. What is this inter-linkage established known as?
Algae,hydrilla,grasshopper,rat,squirrel,crow,maize plant,deer,rabbit,lizard,wolf,snake,peacock,phytoplankton,crustaceans,whale,tiger,lion,sparrow,duck,crane,cockroach,spider,toad,fish,leopard,elephant,goat,nymphae,spirogyra.

Energy enters an ecosystem through

The character of an ecosystem is determined by the environmental factor which is in the shortest supply. This is known as the: