Into how many trophic levels can the detritus food chain be divided?

What is the medium by which the carbon cycle takes place?

The entire sequence of communities that successfully change in a given area is called $P$. The individual transitional communities are termed as $Q$.

In a food chain,a lion is a

Choose an example of a man-made ecosystem.

$A$ 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.