Question

(A).State the constituents of phloem ?(b).how does cork act as a protective tissue?

Answer 1

a)Phloem is made up of four types of element: sieve tubes,companion cells,phloem fibres and the phloem parenchyma  

b)Cells of cork are dead and compactly arranged without intercellular spaces. They also have a chemical called suberin in their walls that makes them impervious to gases and so  water loss due to transportation is prevented.It protects the interior of the plants from entry of harmful microbes,mechanical injury,extremes of temperature etc.