Girth of stem increases due to

Name the tissue which:
$(i)$ allows aquatic plants to float.
$(ii)$ provides flexibility to plants.

$(a)$ Identify the given figures.
$(b)$ State in brief their structure.
$(c)$ Describe the role performed by the two.

$(a)$ What is the function of the tissue present in the bark of a tree?
$(b)$ Which substance is present in the adipocyte? How does it help?

The girth of the stem or root increases due to

List the characteristics of cork. How are they formed? Mention their role.