Select the correct option for the following processes:
$P$ - Formation of organic components from inorganic components
$Q$ - Formation of inorganic components from organic components
Select the correct option for $P$ and $Q$.

An ecosystem creates:

Which of the following is a primary consumer in a maize field ecosystem?

Which of the following ecosystems is both man-made and aquatic?

Consider the following statements about food chain:
$I.$ The transfer of energy from producers to top consumers through a series of organisms is called a food chain.
$II.$ $A$ food chain is always straight and proceeds in a progressive straight line.
$III.$ In a food chain,there is a unidirectional flow of energy from the sun to producers and subsequently to a series of different types of consumers.
Which of the statements given above are correct?

The exchange pool in the carbon cycle is: