Explain the diffusion pressure gradient.

Hint: Diffusion is the process of movement of molecules from the region of higher concentration to the region of lower concentration. The change in the pressure with respect to distance is known as pressure gradient. So the diffusion is caused by the difference in the concentration.

Complete answer:
The cells absorb and exchange water and nutrients from their surroundings. This absorption is being brought about by the difference in the concentration. Diffusion is one such process through which gases and other molecules are exchanged from the cells with their surroundings. This is brought about by the difference in the concentration called the gradient.

Diffusion pressure deficit in the cell is the capacity of the cell to take water from its surrounding. This depends on the concentration of the surrounding. When the diffusion pressure deficit of a cell is greater than the diffusion pressure deficit of another neighbouring cell, the latter will lose water which will be drawn by the former cell. This process takes place till the equilibrium state is achieved that is both the cells attain the same value of the diffusion pressure gradient. This difference in the pressure deficient value between the cells results in the deficiency gradient which is known as the Diffusion pressure gradient.

Note: The water molecules move by the process of osmosis. In this method, the water molecules move from their region of higher concentration to their region of lower concentration across a semi-permeable membrane. In the case of cells, the plasma membrane is a semi-permeable membrane that selectively permits the movement of molecules across the cell.