Question

Find the correct pair of statements :
(i) The influx of Cl into guard cells during stomatal opening is active.
(ii) Entry of sucrose from companion cells into sieve tubes at source involves the expenditure of energy.
(iii) At the sinks, sucrose moves out of phloem by passive transport.
(iv) Efflux of K${}^{+}$ from guard cells during stomatal closure does not involve energy expenditure.

• A. ii, iv
• B. ii, iii
• C. i, iii
• D. iii, iv

Answer 1

The correct option is A ii, iv

The influx of $K^{+}$ into guard cells during stomatal opening is active.

Movement of Sucrose from companion cells to sieve tubes is against its concentration gradient so protons are transported along with it in the opposite direction which involves the use of energy.

At the sink, the sugar moves out of the phloem tube into the cells by active transport.

Efflux of $K^{+}$ from guard cells does not involve the expense of energy as it is along the concentration gradient.

So the correct answer is 'ii, iv'.