Question

In a fully turgid plant cell, which one is zero:
A. Turgor pressure
B. Wall pressure
C. DPD
D. None of the above

Answer 1

It is the decrease in the pressure of the solvent in the water system. It always has a positive value.

Complete answer : A turgid plant cell is a cell which has a turgor pressure (Turgor pressure is defined as the pressure or force that is exerted by the fluid in a cell which pushes the cell membrane against the cell wall). A plant is said to be a healthy plant, if cells of the plant are turgid. It is very much important that plants should have turgidity (refers to the condition of being swollen or turgid). Turgidity is essential for plants because it provides structural support and strength to the cells of plants. Wall pressure is defined as the pressure or force exerted by the cell wall on the plant cells. Wall pressure is always opposite to the turgor pressure. In other words, wall pressure is inversely proportional to the turgor pressure. If wall pressure increases, then turgor pressure gets decreased or vice-versa.

DPD stands for Diffusion Pressure Deficit and it is defined as the difference between the osmotic pressure (OP) and turgor pressure (TP). Osmotic pressure is the pressure which is exerted by the movement of water molecules on the cell wall or the cell membrane by osmosis. When a cell is placed in a hypotonic solution, as the cell absorbs more into it then turgor pressure increases and inversely osmotic pressure decreases. So, for fully turgid plant cells, it’s osmotic pressure becomes equal to the turgor pressure and DPD (diffusion pressure deficit) is equal to zero.

Thus, the correct answer is option C. i.e., DPD

Note : Previously, DPD was named as suction pressure by Renner (1915). Later, it was observed in 1938 by B.S. Meyer. DPD depends on the concentration of the solution, height of the cell.