Question

Assertion (A): Accumulation of \(K^{+}\) ions into guard cells is associated with passive influx of \(Cl^{-}\).
Reason (R): Hence, water potential of guard cells decreases.

• A. Both (A) and (R) are true, (R) is the correct explanation of (A)
• B. Both (A) and (R) are true, (R) is not the correct explanation of (A)
• C. (A) is true, but (R) is false
• D. (A) is false, but (R) is true

Hint:

Guard cell opening: \(K^+\) influx \(\rightarrow\) decrease in water potential \(\rightarrow\) water entry \(\rightarrow\) stomatal opening.

Answer 1

The Correct Option is B

Concept: Stomatal opening is regulated by accumulation of ions in guard cells.

Step 1: Evaluate Assertion.
During stomatal opening: \[ K^{+} \] actively enters guard cells and \[ Cl^{-} \] also accumulates to maintain electrical neutrality. Therefore Assertion is true.

Step 2: Evaluate Reason.
Ion accumulation increases solute concentration. Hence: \[ \Psi_s \downarrow \] and water potential decreases. Thus Reason is also true.

Step 3: Check explanation.
Reason explains a consequence of ion accumulation but does not directly explain why \(Cl^{-}\) enters along with \(K^{+}\). Hence: \[ \boxed{\text{Both true, but R is not the correct explanation}} \]