Question

Turgor Movement is due to
a. Reversible changes in cell volume by efflux and influx of $K^{+}$
b. Synthesis of new cell-wall
c. Irreversible change in cell volume
d. None of the above

Answer 1

Hint: The most common example of turgor movement is the opening and closing of stomata by changes in the turgidity of guard cells. These changes in the turgidity of guard cells are brought about by changes in osmotic pressure due to the movement of potassium ions.

Complete answer:
Turgor pressure refers to the force within the cell that pushes the plasma membrane against the cell wall. It is also known as hydrostatic pressure. It is defined as the pressure measured by a fluid, at a certain point within itself when at equilibrium. Turgor pressure is generally caused by the osmotic flow of water and occurs in plants, fungi, and bacteria. The event is also observed in protists that have cell walls. This phenomenon is not seen in animal cells, because of the absence of a cell wall. This would cause the cell to lyse when under too much pressure. The pressure exerted by the osmotic flow of water is known as turgidity. This is caused by a selectively permeable membrane. This occurs when the water travels from an area with a low-solute concentration, to one with a higher solute concentration.

Hence, the correct answer is option (A).

Note: Turgor growth movements are types of movements that occur due to changes in the turgor pressure of the cells, causing the movement. These are divided into two types-
- Autonomous or spontaneous do not require any external stimulus.
- Paratonic or induced require an external stimulus.