Question

how phosphorylase enzyme open the stomata in starch sugar interconversion theory?

Answer 1

The most important theories arei.The starch-sugar interconversion theory of Stewardii.Active K+transport of Raschkeiii.pH theory of Scarthiv.Proton-potassium pump theory of Levitt.i. The Starch - Sugar interconversion TheorySteward (1964) holds that during the day the enzyme phosphorylaseconvertsstarch to sugar, thus increasing osmotic potential of guard cells causing entry ofwater. The reverse reaction occurs at night bringing about closure.Phosphorylase (day)StarchSugar(stoma opens) night(stoma closes)ii. Proton - Potassium Pump HypothesisLevit in 1974 combined the points in Scarth’s and Steward’s hypothesis andgave a modified version of the mechanism of stomatal movement which wascalled the proton - potassium pump hypothesis.According to this hypothesis K+ions are transported into the guard cells in thepresence of light. The sequence of events taking place arei.Under the influence of light, protons formed by dissociation of malic acidmove from cytoplasm in to the chloroplasts of guard cells.ii.To counter the exit of protons, K+ions enter the guard cells from thesurrounding mesophyll cells.

Answer 2

the starch sugar interconversion Theory steward (1964)holds that during the day the enzyme phosphorylase converts starch to sugar ,thus increasing osmotic potential of guard cells causing entry of water ....phosphorylase (day) Starch Sugar (stoma opens) night stomach closes