Question

Discuss the properties of water in detail and provide at five major roles of water in living organisms. Can you please be thorough when explaining.

Answer 1

Ans.

When we talk about water, we are talking about a natural resource which has got so many importance and without which we humans wouldn't exist.Even the life on earth wouldn't have evolved if there was no water.

Water is a compound made up of 2 atoms of hydrogen and 1 atom of oxygen bonded together.

Following are the properties of water :

1. Boiling and Freezing Points - Eventhough water is small in molecular weight, it has got incredibly high boiling point of 100o C,unlike other hydrides where the boiling point decreases as the molecule size decrease.This is because, the hydrogen bonds in water molecule is so strong that it requires high energy to break down and begin to boil.Same is the case with freezing point also which is 0o C.
2. Surface tension, Heat of Vaporization & Vapor Pressure - Of all the liquids, water has the highest surface tension due to its hydrogen bonding.Water's heat of vaporization is 41 KJ/mol, which is again exceptionally high when compared to other liquids.The presence of very strong intermolecular forces in water molecules make them lower in vapor pressure.
3. Viscosity & Cohesion - The property of a fluid having high flow resistance is called as viscosity.Water is viscous and this viscosity accounts to the strong intermolecular interactions in water.Intermolecular forces between like molecules is called as Cohesion.Water molecules are very cohesive due its polarity and that is the reason why molecules of water are able to hold themselves,even in a single drop.
4. Can exist in all three form's, Solid State(Ice), Liquid & Gas State (steam) - The density of water increases as we decrease it's temperature.Hence when cooled, it becomes dense and becomes ice,which is the solid state of a water molecule.At room temperature water will be in liquid form.This is because at room temperature, the molecules can move quicker which enables them to form less hydrogen bonds,thus the molecules being packed closely together.When we boil the water,its hydrogen bonds gets broken and the molecules start moving so far and apart that rarely any hydrogen bonds are formed and thus water become steam.
5. Universal Solvent - Water can dissolve or dissociate a lots of particles due to its polarity.This is because water molecule has got both negative charge and positive charges.The negatively charged particles of a compound will get attracted to water's positively charged hydrogen atom and positively charged particles of the compound will get attracted to water's negatively charged oxygen atom and this results in the compound to get dissociated.

Let us now discuss five major roles of water in living organisms:

1. Water is an important component as a solvent - The dissolving property of water play's a very vital role in living organisms as it helps in dissolving the components that are important for the survival.For eg. glucose which is derived from the ingested food is broken down with the help of water along with other metabolic processes.
2. Water is an important temperature buffer for cellular respiration - Cellular respiration involves chemical reactions that is often catalysed by enzymes or proteins that are heat sensitive and can only operate at specified temperatures.Water plays the vital role of temperature regulation for these chemical reactions.
3. Water acts as a metabolite in living organisms - A living organism for its survival carries out various metabolic activities which involves series of chemical reactions.Water itself is a chemical or a metabolite involved in such reactions which is important for a living organisms metabolism.For example: In plants, the process of converting light energy into food through photosynthesis occurs only if water is available. In animals, water helps in respiration and helps converting ATP into ADP and phosphoric acid, the process by which cellular energy is generated.
4. Water plays an important role in waste excretion - Water helps in excreting waste from the body by flushing out the toxins from the body while retaining the necessary nutrients required.It helps in hydrating the colon contents and keeping it soft and loosend and thus promoting easy evacuation from the intestine.Water is an essential component of kidney systems which is important for eliminating wastes from blood,urine etc.
5. Water serves as a living environment - Organisms like fish requires water to survive as they directly breathe oxygen dissolved in water.They require water supply to access oxygen and otherwise are left suffocated.Apart from providing a medium for survival, they also insulate the living environment for them by keeping them warm enough to survive during heavy winter months when the surface of water is filled with ice layers.