Biology » The Chemistry of Life » Inorganic Compounds

Role of Water in Life

The Role of Water in the Maintenance of Life

Up to 65% of our bodies are made up of water. Water is an inorganic compound made up of two hydrogen atoms and one oxygen atom. Its molecular formula is \(\mathrm{H_2O}\). Water plays an important role in the maintenance of biological systems.


Image credit: Claudia via Pixabay

Temperature regulation

In humans, the sweat glands produce sweat which cools the body as it evaporates from the body surface in a process called perspiration. In a similar way, plants are cooled by the loss of water vapour from their leaves, in a process called transpiration.

Form and support

Water is an important constituent of the body and plays an important role in providing form and support in animals and plants. Animals, such as worms and jellyfish, use water in special chambers in their body to give their bodies support. This use of water pressure to provide body form, and enable movement is called a hydrostatic skeleton . Plants grow upright and keep their shape due to the pressure of water (turgor pressure) inside the cells.

Transport medium

Water transports substances around the body. For example, water is the main constituent of blood and enables blood cells, hormones and dissolved gases, electrolytes and nutrients to be transported around the body.

Lubricating agent

Water is the main constituent of saliva which helps chewing and swallowing and also allows food to pass easily along the alimentary canal. Water is also the main constituent of tears which help keep the eyes lubricated.

Solvent for biological chemicals

The liquid in which substances dissolve is called a solvent. Water is known as the universal solvent as more substances dissolve in water than in any other liquid.

Medium in which chemical reactions occur

All chemical reactions in living organisms take place in water.


Water takes place in several classes of chemical reactions. During hydrolysis reactions, water is added to the reaction to break down large molecules into smaller molecules. Water can also be split into hydrogen and oxygen atoms to provide energy for complex chemical reactions such as photosynthesis.

TemperatureStructure and supportLubrication
Sweating helps human bodies cool down.Jellyfish and worms use a hydrostatic (water pressure) skeleton to keep their body shape.Water helps maintain the upright structure of plants.Water is an important lubricant in the eye.

Video: Properties of Water

The Amoeba Sisters video explores some properties of water. It’s all about those hydrogen bonds.

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