MEANS OF TRANSPORT
Passage of materials into and out of the cellsis carried out by the following methods - diffusion, faci active transport
Diffusion Movement by diffusion is passive, slow, and occurs along the concentration gradient, le, from region of higher concentration to region of lower Low diffusion concentration, provided the cell membrane is permeable to it. No energy pressure of dye expenditure takes place Diffusion is very important to plants, since it is the only means for gaseous
movement within the plant body. The diffusing molecules or ions exert a
pressure called diffusion pressure (DP). his can be defined as the potential Hig
ability of a molecule or ion (be it a solid, liquid or gas) to diffuse from an area
of its greatest concentration to an area of lesser concentration. The diffusion
presure is direcly proportional to the concentration or the number of diffursing
particles, ie, greater the concentration of diffusing particles in the system, their
difusion pressure will also be greater and vice versa Water High diffusion pressure of dye Dye.
Fig.: Demonstration of diffusion
er has the maximum diffusion pressure. When solute partides are aded to t, diffusion pressure gets lowered
usion pressure deficit or DPD. Due
Diffusion pressure of a solution, as compared to the pure state, is known as diff to the presence of diffusion pressure deficit, a solution will always tend to make up the deficit by absorbing water. Hence
t is also called suction pressure. Factors influencing rate of diffusion All the factors which bring about changes in free energy, will ultimately infiluence diffusion. Rise in temperature increases the rate of diffusion, due to increase in kinetic energy
The rate of diffusion is inversely proportional to the square root of the density of the diffusing substance (Graham's law of diffusion)
D Where D diffusion and d densityte of diffusion decreases with density of the medium, and is directiy proportional to the diffusion pressure gradient.
