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Transport in Plants

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Biology

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Biology

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

What cause the opening and closing of guard cells of stomata during transpiration ?


The change in the turgidity of guard cells results in closing or opening of stomata. The inner and outer walls of the guard cells differ in thickness, the inner walls are thick while the outer are thin. When the guard cells absorb water their turgidity increases, thus the thin outer walls bulge out and force the inner walls into a crescent shape. The change in shape is aided due to the radial orientation of the microfibrils in the cell walls of the guard cells. These microfibrills help the guard cells to bulge out thus opening the stomata. During tranpiration the loss of water makes the guard cells lose turgidity, the elastic inner walls regain their original shape, the guard cells become flaccid and the stomata closes.

 

 

 

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Give the term for the ability to resist a pulling force.

Tensile strength
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Why the cortex produces no resistance to movement of water ?

The cortical cells are loosely packed and produce no resistance to movement of water via cell walls or apoplast.
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Who introduced the apoplast—symplast concept ?

E. Munch (1930).
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What is transmembrane pathway ?

The movement of water through cell membranes is called trans membrane pathway.
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Why the water is forced to move through cell membrane beyond endodermis ?

Water is forced to move through cell membranes beyond endodermis because of the suberin (waxy substance) present on radial walls of endodermal cells blocks water and solute movement through cell walls of endodermis. 
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