Question

Mention two main functions of water for living organisms.

Answer 1

Hint:Water is an important compound for the survival of living organisms. The chemical formula for water is ${H_2}O$. It is a liquid with no color and taste. A molecule of water contains two hydrogen atoms and one oxygen atom.

Complete step by step answer:
Water is an important compound for the survival of living organisms. The human body consists of about $65\% $ water and some plants contain $95\% $ water. A water molecule has one oxygen atom and two hydrogen atoms in it. We know hydrogen and oxygen exist as gases whereas water made by their combination is a liquid.
An interesting feature is that hydrogen burns with a pop sound and oxygen are used as a supporter in the combustion reactions. But water is used as the fire extinguisher.
Almost all living organisms have water content in their body.
Water is mainly used for drinking to survive as it is important for cell metabolism
Water is a solvent.
Water acts as a solvent in the chemical reactions that take place in the living cells.
Almost all compounds dissolve in water.
Therefore it is used as a solvent in chemical reactions. It is used in the hydrolysis reaction.
Water breaks down the food we intake and thus helps in the digestion process.
It is also used as a transport medium through which compounds are transported in and out of the cell.
Water acts as a metabolite. All the chemical reactions that occur in the cell and that occur in living organisms are called metabolic reactions. Water is the main chemical involved in these metabolic reactions that are necessary for the survival of living organisms.
For example, in the photosynthesis process that takes place in plants, water acts as a metabolite.
Through the process of photosynthesis, plants convert sunlight to their food. So during the first state water splits as hydrogen and oxygen. Oxygen is given out to the atmosphere and the hydrogen is used to produce glucose in plants.
Another example where water acts as a metabolite is the respiration process in animals where water splits ATP into ADP and phosphoric acid. Energy is released as a byproduct of this reaction.
Organisms like fishes need water to breathe. They directly breathe oxygen dissolved in water. Without water, they couldn’t respire.
Another important function of water is that it acts as a temperature buffer.
Enzymes are very sensitive to temperature. They need an optimum temperature for its functioning. High temperature may lead to denaturation of the enzymes. Water helps the enzymes to remain at that optimum temperature.
Water has a high heat of vaporization and heat capacity and this is responsible for the moderation of the climate and body temperature of living organisms. Thus water buffers the temperature changes. Water absorbs the heat without raising the temperature in the body of living organisms.


Note:
Water has chemical and biological significance. Due to the extensive hydrogen bonding with polar molecules, it acts as a good solvent. Due to high heat capacity, it is used as a temperature buffer. Water has high specific heat, surface tension, dipole moment, and dielectric constant. Due to these properties water has an important role in the biosphere.