When kept in water, raisin swells in size. Name and explain the phenomenon involved with the help of a diagram. Give three applications of the phenomenon.

Explanation

Raisins swell in size on keeping in water. This happens due to the phenomenon of osmosis. The outer skin of raisin acts as a semi-permeable membrane. Water moves from a place of lower concentration to a place of higher concentration through the semi-permeable membrane. Thus water will enter the raisins and make them swell.
Applications of the phenomenon
(i) Movement of water from soil into plant roots and subsequently into upper portion of the plant is partly due to osmosis. (ii) Preservation of meat against bacterial action by adding salt. (iii) Preservation of fruits against bacterial action by adding sugar. Bacterium in canned fruit loses water through the process of osmosis, shrivels and dies. (iv) Reverse osmosis is used for desalination of water.