Question

Opening and closing of stomata is due to: a) pressure of gases inside the leaves b) changes of turgor pressure in guard cells c) effects of hormone d)their genetic constitution

Answer 1

Dear student,

Opening and closing of stomata is due to change of turgor pressure in guard cells.
​​​​Generally stomata are open during the day and closed in night.During day,water from other cells enter into guard cells and they become turgid.As a result,convex walls bulge out and inner concave walls go away from each other causing stomata open.
But druing night,water from guard cells move out causing flaccidness as a decrease in turgor pressure .This causes stomata to close.
This mechanism has been explained by many theories-

1. Proton-pump theory
2. ph theory of scarth
3. Starch sugar theory of Steward
4. Active transport of k+ .

Regards.
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