Question

The metal ion involved in the stomatal regulation is
A. Iron
B. Magnesium
C. Zinc
D. Potassium

Answer 1

Hint: Plants need to exchange gasses and remove excess water via stomata
Stomatal regulation is controlling the opening and closing of stomata with the help of osmotic pressure.

Complete answer:

(1) Epidermal cell
(2) Guard cell
(3) Stoma
(4) Movement of potassium ions
(5) Movement of water molecules
(6) Vacuole
The opening and closing of stomata are regulated by guard cells with the help of osmotic pressure.
Stomata open when the guard cells fill up with water (becomes turgid).
Here the inner and outer layer of the guard cells moves outwards and stomata close when water comes out of the guard cells (becomes flaccid).
Here inner and outer layers of the guard cells move towards the pore.
Most widely it is accepted that due to potassium ions movement, the turgidity of the guard cells changes. The guard cells become turgid as the potential ions move inside the guard cells, which lowers the concentration of water inside the guard cells. So water moves inside the guard cells.
Similarly, when the potassium ions move outside of guard cells, the concentration of water becomes higher on the outside. So water moves outside of the guard cells.

So, the correct answer is “Option A”.

Note: Stomata (singular: stoma) are pores present in the leaves of the plant.
A higher number of stomata are present on the lower surface of the leaves. The pore is surrounded by two bean-shaped cells (parenchyma cells) called guard cells.