Importance of WATER in cell

1. Maintaining body temperature

•  Water helps distribute heat in the body. Excess heat is then eliminated through perspiration, urination and defaecation. Evaporation of sweat causes loss of body heat and cools the body surface.

2. Providing support 

• Water supports the structure of cell because 90% of the protoplasm is made up of water.

3. Transport medium

• Blood plasma is about 90% water. It contains many biological molecules such as sugars, amino acids and also respiratory gases (oxygen and carbon dioxide) which dissolve in water.
• These substances are then transported from one part of the body to another. Waste products such as urea are excreted from the body in the urine.

4. Maintaining osmotic balance and turgidity

•  In animals, the concentration of dissolved inorganic salts in water is important in maintaining the osmotic balance between the blood and interstitial fluid.
• In plants, the cell sap in the vacuole contains water and dissolved substances. A high osmotic concentration in plant cells encourages water to enter the cells. This causes the cells to be turgid. Turgidity provides support in plants.

5. Medium for biochemical reactions

• Most of the biochemical reactions can only occur when there is water.
• Water is involved in the breaking down of proteins, lipids and carbohydrates in the food we eat. 
• Enzymatic reactions also require water.