$E. coli$ in the human colon behaves as:

Myrmecophily is a beneficial association between a flowering plant and

Match the following columns:

Column-$I$	Column-$II$
$P$. Calotropis	$I$. Special chemical
$Q$. Cactus and Acacia	$II$. Camouflage
$R$. Monarch butterfly	$III$. Thorns
$S$. Some species of insects and frogs	$IV$. Glycosides

Species $A$ $(-)$ and Species $B$ $(O)$ show which of the following interactions?

Name the association in which one species produces a poisonous substance or a change in environmental conditions that is harmful to another species.

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