Experiment: To demonstrate endosmosis in raisins

This is an experiment to show endosmosis in raisins (or in gram seeds). It is a part of Class 12 Biology Practical work. It is one of the major experiments. It comes under Plant Physiology.  It is also a part of Class 11 minor experiment or for Spotting. A simplified version of the experiment for your Practical file is given below:                                                          

                                                     Experiment

Aim: To demonstrate endosmosis in raisins and find the percentage of water absorption. 

Principle: Water moves from its higher concentration to lower concentration. It can pass through a selectively permeable membrane like the plasma membrane of cells (osmosis).

Materials Required: A few raisins, digital weighing scale, beaker, water, blotting paper. 

Procedure:

1.     Take three or four raisins and weigh it on a digital weighing scale. Note the weight W₁.

2.     Soak them by putting them in a beaker filled with pure water.

3.     After two hours, take out the raisins and wipe them dry using a blotting paper.

4.     Weigh the raisins on the digital weighing scale. Note the weight W₂.

Observation:

After a period of time, the raisins absorb water and get swollen because of endosmosis.

Initial weight of raisins = W₁ = _________

Weight of swollen raisins = W₂ = _________

Weight of absorbed water = W₃ = W₂ – W₁ = __________

Percentage of water absorbed by raisins = (W₃/W₁)  x 100 = ________ %

Result:

Raisins exhibit endosmosis and absorb water when soaked in it.

The percentage of water absorption of the given sample of raisin = _______%