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  • Which of the following as an active role in stomatal opening?Option: 1 <img a

Which of the following as an active role in stomatal opening?

Option: 1

Cl^{-}


Option: 2

K^{+}


Option: 3

H^{+}


Option: 4

All of these


Answers (1)

best_answer
 

Mechanism of Stomatal Opening -

  • Stomata open and close as a result of osmosis.
  • Under hot and dry conditions, when water loss due to evaporation is high, stomata must close to prevent dehydration.
  • Guard cells actively pump potassium ions (K +) out of the guard cells and into surrounding cells. 
  • This causes water in the enlarged guard cells to move osmotically from an area of low solute concentration (guard cells) to an area of high solute concentration (surrounding cells). 
  • The loss of water in the guard cells causes them to shrink. This shrinkage closes the stomatal pore.
  • When conditions change such that stomata need to open, potassium ions are actively pumped back into the guard cells from the surrounding cells. 
  • Water moves osmotically into guard cells causing them to swell and curve.
  • The outer wall of guard cells bend outwards because it is thin and elastic.
  • The inner wall does not bend as it is thick and inelastic.
  • This bending of outer wall causes opening of stomatal pore.

 

Guard cells actively pump potassium ions (K^{+}) out of the guard cells and into surrounding cells. Hence, the correct answer is option b.

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