what is concentration gradient ?
Concentration gradient refers to the difference in concentrations of a substance across a semipermeable membrane. For example, Take a container and partition it into two equal halves A and B, by placing a semipermeable membrane in between. Now take 50 ml of water on both sides of the membrane. Dissolve 5 gms of sugar on side A and 10 gms on side B. Now water molecules have interacted with the sugar molecules on both sides but since the amount of sugar in side A is less, there would be more free water molecules in this side than in side B because it has a higher sugar concentration. In this case, water will move from side A to side B. Concentration gradient plays a very important role in the movement of substances in and out of a cell in a living system.
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