Give one basic functional difference between phellogen and phelloderm.

Arrange the following in the sequence you would find them in a plant starting from the periphery: phellem,phellogen,phelloderm.

During secondary growth of plants,stem phellogen cuts off cells on both sides. The outer cells get differentiated into ...$A$... and the inner cells get differentiated into ...$B$... cortex.
Choose the correct combination of $A$ and $B$ with reference to the above statement.

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$(a)$ Lenticels	$(i)$ Phellogen
$(b)$ Cork cambium	$(ii)$ Suberin deposition
$(c)$ Secondary cortex	$(iii)$ Gaseous exchange
$(d)$ Cork	$(iv)$ Phelloderm

Choose the correct answer from the options given below:

Knots in stems are formed due to

The vascular cambium normally gives rise to