Water and its biological importance for living organisms – Schreoshi Khan, WCHS

Transportation

Waters unique properties allows it to transport substances easily. Because of hydrogen bonding, water has strong cohesion. This is important in enabling water to move in a continuous column (transpiration stream) through the xylem and out the leaves during transpiration in plants, preventing plants from wilting and providing water for photosynthesis. Cohesion also provides surface tension which permits small invertebrates (water striders) to live on the surface of water, providing a habitat away from predators. [2]

A good solvent

Water also acts as a good solvent as it is a dipolar molecule. When polar or ionic molecules are mixed with water, the compound dissociates because the forces of attraction between the partially negative oxygen from water and the partially negative atom or ion of the compound are stronger than the bonds within the compound itself. These substances that dissolve in water are known as being hydrophilic. Water therefore is a fundamental component in blood plasma, as a large variety of substances such as minerals, red blood cells and metabolic waste can dissolve in it to be transported around the body. Dissolution of metabolic waste such as urea and ammonia are essential as these substances if undiluted can be toxic and need to be quickly removed from the body. [3] In addition, another reason for the importance of water as a biological molecule is its viscosity. This makes it a good base for lubricating fluid such as mucus and tissue fluid, allowing more efficient movement of the heart, joints, and the lungs when during breathing. 

Structural Support

Water also provides structural support to organisms by creating turgor pressure in plant cells, maximising photosynthesis by maintaining maximum surface area and increasing light absorption. Furthermore, by being incompressible, water allows organisms such as earthworms to have hydro-skeletons, therefore providing structural support, as well as providing aquatic organisms buoyancy. [4]

Thermoregulation

A large amount of heat needs to be supplied to water to raise its temperature, meaning that it has a high specific heat capacity which is significant as it ensures that an organisms internal conditions remain stable. It is important for temperature to remain constant to prevent enzymes from denaturing or to ensure metabolic activity is regulated by maintaining enzyme activity. Apart from this, water also has a high latent heat of vaporisation as a large amount of energy is needed to overcome hydrogen bonds between water molecules. [5] At high temperatures, water is released to the skins surface as sweat and evaporated away, transferring thermal energy away from the skin in the form of radiation, therefore cooling the body down and returning the body to a constant temperature.[6]

Metabolite

Water is involved in many essential chemical reactions needed to sustain life, such as photosynthesis which important in the production of sugars needed for plant growth, and is a metabolite. Water also creates a buffer against the effects of toxic acids and bases which would otherwise cause enzymes to denature. [7]

[1] Miss Estruch Biology (The importance of water) – https://www.youtube.com/watch?v=SS2Fv3506Tg

[2] Miss Estruch Biology (The importance of water) – https://www.youtube.com/watch?v=SS2Fv3506Tg

[3] https://pmt.physicsandmathstutor.com/download/Biology/A-level/Notes/WJEC-Old/Unit-1/1-Biological-Compounds/The%20Biological%20Importance%20of%20Water.pdf

[4] https://sitn.hms.harvard.edu/uncategorized/2019/biological-roles-of-water-why-is-water-necessary-for-life/

[5] Miss Estruch Biology (The importance of water) – https://www.youtube.com/watch?v=SS2Fv3506Tg

[6] https://www.livescience.com/52332-why-is-water-needed-for-life.html

[7] https://www.livescience.com/52332-why-is-water-needed-for-life.html