Plants growing on sand and gravel are called

Large woody vines are commonly found in .......

$A$ person moves from Delhi to Shimla during the hot summer days. This is an example of which of the following?

Savannas are .....

The upper part of sea water mainly contains

How many of the following statements are correct about niche?
$i$. It denotes the functional role played by an organism.
$ii$. It deals with the flow of energy from one organism to another.
$iii$. As soon as a niche is left vacant,other organisms fill that position.
$iv$. The same niche is shared by two or more species.
$v$. Organisms living in the same habitat differ in their niches.