Fill in the blanks

(a) Cork cells possesses ______ on their walls that makes it impervious to gases and water.

(b) _______ have tubular cells with perforated walls and are living in nature.

(c) Bone possesses a hard matrix composed of _______ and ______ .

a) Suberin

Suberin present in the cork cells of plants acts as a barrier for movement of water and gases from the cells.

b) Sieve tubes of phloem

Sieve tubes found in phloem have tubular cells with perforated walls. They are living cells.

c) Calcium and phosphorus

The hard matrix of brain is composed of calcium and phosphorus salts.