Question

Stomatal movements are influenced by a number of environmental factors. Which of the following statements is/are incorrect regarding this?
(i) Blue light keeps stomata open during the day promoting the movement of $K^{+}$ ions into guard cells.
(ii) Increased $C{O}_2$ concentration reduces the pH of guard cells which promotes conversion of sugar into starch, ultimately causing closure of stomata.
(iii) Abscisic acid, under stress conditions, causes rapid movement of $K^{+}$ ions into guard cells.
(iv) Highly concentrated sucrose or salt solution when applied over to stomata, results in stomatal opening.

• A. (i) and (ii)
• B. (iii) and (iv)
• C. (iii) only
• D. (iv) only

Answer 1

The correct option is A (i) and (ii)

Abscisic acid (ABA), is called as stress hormone as it causes closing of stomata under water stress conditions by causing rapid movement of K+K+ ions out of the guard cells. Highly concentrated sucrose/salt solution results in stomatal closure.