The flora and fauna in lakes or ponds are known as:

Given below are two statements.
Statement $I$: Habitat consists of numerous niches.
Statement $II$: Niche is an area where a species lives and prospers.
In the light of the above statements,choose the correct option.

In which of the following is a thick layer of fat (blubber) found under the skin?

Match the following adaptations in Column $I$ with the respective organisms in Column $II$.

Column $I$	Column $II$
$i$. Thick cuticle on leaf surface	$a$. Desert lizards
$ii$. Leaves reduced to spines	$b$. Archaebacteria
$iii$. Burrow into sand to escape from heat	$c$. Desert plants
$iv$. Hot springs	$d$. Opuntia

An association of individuals of different species living in the same habitat and having functional interactions is

Many freshwater fishes cannot live in seawater and vice versa because of: