When pheromones are secreted onto the skin surface,their scent affects . . . . . . .

$A$ plant growing on another plant without drawing any nourishment is

In an aquarium,two herbivorous species of fish are living together and feeding on phytoplanktons. As per the Gause's Principle,one of the species is to be eliminated in due course of time,but both are surviving well in the aquarium. Give possible reasons.

Explain commensalism with the example of an egret and cattle.

$A$ female fig wasp enters the syconium of a fig,pollinates the flowers and lays eggs in the ovaries of some of the flowers. The young larvae grow up,eat (and kill) some,but not all of the seeds and complete their life cycle.
The fig is completely dependent on fig wasps to pollinate its flowers and the fig wasp requires figs to complete its life cycle.
The interaction between figs and fig wasps has aspects of:
$I.$ mutualism
$II.$ host-parasite interaction
$III.$ competition
$IV.$ ammensalism
$V.$ protocooperation
Select the correct option.

In brood parasitism as observed in Asian koel and Indian crow,the eggs of . . . . . . .