The movement of nutrients from non-living components to living components and back to non-living components in a cyclic manner is known as:

Which of the following is associated with a major ecological role?

What is the full form of $PAR$?

In a given ecosystem,the number of individuals in a species remains more or less constant over a period of time. The constancy of this number is maintained by:

Identify the organism that is not included among producers.

$A$ 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.