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Give reasons for
(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.

 

Answers (1)

Sol.
a) Meristamatic tissue cells divide continuously and have a prominent nucleus and dense cytoplasm. As they are diving continously they need not to store food or waste products hence they lack vacuoles.
b) Sclerenchyma doesn’t contain intercellular spaces because its cellwall is lignified. These are densely packed and provide protection to the plant and mechanical strength.
c) The cruncy and granular feeling upon chewing the pear fruit is because of sclerenchyma tissue. The sclerenchyma cells are of two types- fibres and sclereids. The sclereids give a crunchy feeling to the pear fruit because it provides support and hardens the tissue
d) The branches of a tree move and bend freely in high wind velocity because of the presence of collenchyma that adds the property of flexibility.
e) It is difficult to pull out the husk of a coconut tree because it is made up of sclerenchyma tissues which are dead cells. This gives rigidity and stiffness.

 

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