What is an ecosystem service? List any four important ecosystem services provided by the natural ecosystems. Are you in favour or against levying a charge on the service provided by the ecosystem?

Define the following terms:
$(i)$ Sere
$(ii)$ Standing state

$A$ farmer harvests his crop and expresses his harvest in three different ways.
$(a)$ $I$ have harvested $10$ quintals of wheat.
$(b)$ $I$ have harvested $10$ quintals of wheat today in one acre of land.
$(c)$ $I$ have harvested $10$ quintals of wheat in one acre of land,$6$ months after sowing.
Do the above statements mean one and the same thing? If your answer is yes,give reasons. If your answer is 'no',explain the meaning of each expression.

Among the ecosystem services are control of floods and soil erosion. How is this achieved by the biotic components of the ecosystem?

Identify the organism included in the first trophic level of a food chain.

In ecosystem services,soil formation accounts for about.....