Tag: osmosis in plants

In a fully turgid cell there will be no net movement of water. Neither water will move inside nor move outside. This is because DPD will be zero. DPD can be zero, when the osmotic pressure, which causes movement of water inside the cell equals to turgor pressure, which opposes the entry of water inside the cell.

When the mesophyll cells lose water the concentration of solutes will increase. Consequently, the OP will increase concomitantly, there will be a drop in turgor and TP will decrease. These changes will increase the DPD. Water moves from lower DPD to higher DPD, thus, water will gain entry into the cells, whose DPD has increased.

Answer is option B i.e. "OP"
Hypotonic solution is one in which the solution kept outside the cell has lower solute concentration than the fluid inside the cell. The process being investigated is osmosis. Osmosis is the diffusion of water molecules across a semi-permeable membrane from a more dilute solution (with a lower solute concentration) to a less dilute solution (with a higher solute concentration). Therefore cell absorbs or sucks water with a force equal to O.P

Diffusion Pressure Deficit = osmotic pressure - wall pressure. Wall pressure is the same as Turgor pressure. When a cell is placed in a hypotonic solution water enters the cell. Hence its osmotic pressure decreases and the turgor pressure increases. In a fully turgid cell the turgor pressure becomes equal to the osmotic pressure. Hence the Diffusion Pressure Deficit becomes zero in a turgid cell. Thus the correct answer is option B.

Suction pressure is the decrease in the diffusion pressure of solution over its pure state due to the presence of solute particles in it. The concentration of solute is higher in root hair cells as compared to soil water. So suction pressure builds up and water is drawn towards root hair cells. These water molecules are transported to different parts of the plant. So, the correct answer is 'Suction pressure'.

DPD is the diffusion pressure deficit. When a cell is put in a hypertonic solution (solution with the high concentration of solutes than the solute concentration ), a water potential or DPD gradient is created between the cell and the external solution. Hence the water diffuses out of the cell; the process is called exosmosis. Thus water movement is due to DPD gradient not because of turgor gradient, diffusion gradient and osmotic gradient.