Question

Give reasons for the following :

(a) Aquatic plants can float on water.
(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.

Answer 1

(a) Aquatic plants have large air cavities in their parenchyma to give buoyancy to plants which help them float.

(b) The cells of sclerenchymatous tissue are long and narrow as the walls are thickened due to lignin (a chemical substance which acts as cement and hardens them). Since they are lignified there is no intercellular space between the cell.

(c) We get a crunchy and granular feeling when we chew pear fruit. It is due to the presence of stone cells (sclerenchyma).

(d) The flexibility in plants is due to a permanent tissue, collenchyma. It allows easy bending in various parts of a plant (leaf, stem) without breaking. It also provides mechanical support to plants.

(e) The husk of a coconut is made of sclerenchymatous tissue. They are lignified and make it difficult to pull.