The conversion of starch into organic acids i | vedclass

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(B) According to the starch-sugar interconversion theory (proposed by Steward),the opening and closing of stomata are regulated by the concentration o

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Stomatal opening

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(B) According to the starch-sugar interconversion theory (proposed by Steward),the opening and closing of stomata are regulated by the concentration of sugar and starch in the guard cells.During the day,the $pH$ of the guard cells increases due to photosynthesis (consumption of $CO_2$).This high $pH$ triggers the enzyme phosphorylase to convert starch into glucose$-1-$phosphate (an organic acid/sugar derivative).This increases the osmotic pressure of the guard cells,causing water to enter from adjacent cells via endosmosis.The resulting turgor pressure causes the stomata to open.Conversely,at night,the $pH$ decreases,and glucose$-1-$phosphate is converted back into starch,leading to stomatal closure.

The conversion of starch into organic acids is essential for:

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