$P$-proteins are associated with

Match the following columns:

Column-$I$	Column-$II$
$P$. Parenchyma	$I$. No thickening
$Q$. Collenchyma	$II$. Pectin thickening
$R$. Sclerenchyma	$III$. Lignin thickening

Companion cells are usually seen associated with

Assertion : Vessels are more efficient for water conduction as compared to tracheids.
Reason : Vessels are dead lignified.

Which of the following is absent in most of the monocotyledons?

Deciduous plants shed their leaves during hot summer or in autumn. This process of shedding of leaves is called abscission. Apart from physiological changes,what anatomical mechanism is involved in the abscission of leaves?