Thursday, February 11, 2010

EXPALIN HOW THE DEVELPOMENT OF THE CUTICLE AND THE VASCULAR SYSTEM INFLUENCE THE EVOLUTION OF PLANT ON LAND.?

Vascular plants often have a well-developed cuticle, a waxy layer that covers the epidermis of those plant parts exposed to the air. A cuticle helps reduce water loss, which is a significant environmental challenge for land plants.





They possess tissues that are specialized for internal transport of water (xylem) and food (phloem).





The water conducting cells in the xylem are dead at maturity; only their cell walls remain. Xylem cell walls contain lignin a very rigid substance that provides the strength and support that allows plants to grow larger.


Water transport is enabled by transpiration of land plants %26gt; loss of water vapor through stomata %26gt; new water taken through roots.





The food, sugar molecules, pass through the plasma membrane of phloem cell, travel to the opposite side of the cell by cytoplasmic streaming, and leave the cell through the plasma membrane, enter the next cell etc.


In parenchyma cells, living thin-walled cells, food is stored mostly in form of starch.

No comments:

Post a Comment