question_answer

  Give reasons: (a) Meristematic cells have a prominent nucleus and dense cytoplasm but they lack vacuole. (b) Intercellular spaces are absent in sclerenchymatous tissues. (c) We get a crunchy and granular feeling when we chew pear fruit. (d) Branches of a tree move and bend freely in high wind velocity. (e) It is difficult to pull out the husk of a coconut tree.

Answer:

                  The characteristics of cork are as follows: (a) Cells of cork are dead at maturity. (b) These cells are compactly arranged. (c) Cells do not posses intercellular spaces. (d) Cells possess a chemical substance 'suberin' in their walls. (e) There are several thick layers. As plants grow older, a strip of secondary meristem replaces the epidermis of the stem. Cells on the outside are cut off from this layer. This forms the several-layer thick cork or the bark of the tree.