<h2 class="section-header"><strong class="title">The Role of Water in the Maintenance of Life</strong></h2>
<p class="para">Up to 65% of our bodies are made up of water. Water is an inorganic compound made up of two hydrogen <a data-lesson="chemical-reactions-molecules" data-subject="biology" data-tutorial="chemical-foundation-of-life" href="https://app.ulearngo.com/biology/chemical-foundation-of-life/chemical-reactions-molecules">atoms</a> and one <a data-lesson="transport-of-oxygen-in-the-blood" data-subject="biology" data-tutorial="respiratory-system" href="https://app.ulearngo.com/biology/respiratory-system/transport-of-oxygen-in-the-blood">oxygen</a> atom. Its molecular formula is \(\mathrm{H_2O}\). Water plays an important role in the maintenance of biological systems.</p>
<div class="wp-caption alignnone" id="attachment_96352" style="width: 800px"><a href="https://data.ulearngo.com/assets/2a803d7d-abf6-4f16-9f4c-b2b08658a12a"><img alt="water-pebble-waves" class="size-full wp-image-96352" height="530" src="https://data.ulearngo.com/assets/2a803d7d-abf6-4f16-9f4c-b2b08658a12a" width="800"/></a><p class="wp-caption-text">Image credit: Claudia via Pixabay</p></div>
<h3 class="para"><strong>Temperature regulation</strong></h3>
<p class="para">In humans, the sweat glands produce sweat which cools the body as it evaporates from the body surface in a process called <i class="emphasis">perspiration</i>. In a similar way, plants are cooled by the loss of water vapour from their leaves, in a process called <i class="emphasis">transpiration</i>.</p>
<h3 class="para"><b class="emphasis">Form and support</b></h3>
<p class="para">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 <i class="emphasis">hydrostatic skeleton </i>. Plants grow upright and keep their shape due to the pressure of water (<i class="emphasis">turgor pressure) </i>inside the cells.</p>
<h3 class="para"><b class="emphasis">Transport medium</b></h3>
<p class="para">Water transports substances around the body. For example, water is the main constituent of <a data-lesson="blood-2" data-subject="biology" data-tutorial="human-biology" href="https://app.ulearngo.com/biology/human-biology/blood-2">blood</a> and enables blood cells, <a data-lesson="lipid-derived-hormones-or-lipid-soluble-hormones" data-subject="biology" data-tutorial="endocrine-system" href="https://app.ulearngo.com/biology/endocrine-system/lipid-derived-hormones-or-lipid-soluble-hormones">hormones</a> and dissolved gases, electrolytes and nutrients to be transported around the body.</p>
<h3 class="para"><b class="emphasis">Lubricating agent</b></h3>
<p class="para">Water is the main constituent of saliva which helps chewing and swallowing and also allows <a data-lesson="ingestion" data-subject="biology" data-tutorial="digestive-system" href="https://app.ulearngo.com/biology/digestive-system/ingestion">food</a> to pass easily along the alimentary canal. Water is also the main constituent of tears which help keep the eyes lubricated.</p>
<h3 class="para">Solvent for biological chemicals</h3>
<p class="para">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.</p>
<h3 class="para">Medium in which chemical reactions occur</h3>
<p class="para">All chemical reactions in living organisms take place in water.</p>
<h3 class="para">Reactant</h3>
<p class="para">Water takes place in several classes of chemical reactions. During <a data-lesson="hydrolysis-of-biological-macromolecules" data-subject="biology" data-tutorial="biological-macromolecules" href="https://app.ulearngo.com/biology/biological-macromolecules/hydrolysis-of-biological-macromolecules">hydrolysis</a> 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 <a data-lesson="biology-203-glossary-9" data-subject="biology" data-tutorial="cell-metabolism" href="https://app.ulearngo.com/biology/cell-metabolism/biology-203-glossary-9">energy</a> for complex chemical reactions such as photosynthesis.</p>
<table>
<tbody>
<tr>
<td><b class="emphasis">Temperature</b></td>
<td colspan="2"><em class="emphasis">Structure and support</em></td>
<td><b class="emphasis">Lubrication</b></td>
</tr>
<tr>
<td>
<div class="figure"> <a href="https://data.ulearngo.com/assets/23b3013f-a872-4516-b0a7-e018cd6373eb"><img alt="sweating" class="size-full wp-image-98683 alignnone" height="149" src="https://data.ulearngo.com/assets/23b3013f-a872-4516-b0a7-e018cd6373eb" width="99"/></a></div>
</td>
<td>
<div class="figure"> <a href="https://data.ulearngo.com/assets/9ed3faf3-2bc7-48c1-bd1d-80a5c9608c0d"><img alt="" class="size-full wp-image-98684 alignnone" height="137" src="https://data.ulearngo.com/assets/9ed3faf3-2bc7-48c1-bd1d-80a5c9608c0d" width="206"/></a></div>
</td>
<td> <a href="https://data.ulearngo.com/assets/fe0c66a8-bf35-4ebb-a807-ca18b9024ef6"><img alt="" class="size-full wp-image-98685 alignnone" height="158" src="https://data.ulearngo.com/assets/fe0c66a8-bf35-4ebb-a807-ca18b9024ef6" width="99"/></a></td>
<td>
<div class="figure"> <a href="https://data.ulearngo.com/assets/f2dc502e-af89-43b6-ac39-fcc51a93d765"><img alt="" class="size-full wp-image-98686 alignnone" height="155" src="https://data.ulearngo.com/assets/f2dc502e-af89-43b6-ac39-fcc51a93d765" width="206"/></a></div>
</td>
</tr>
<tr>
<td>Sweating helps human bodies cool down.</td>
<td>Jellyfish and worms use a hydrostatic (water pressure) skeleton to keep their body shape.</td>
<td>Water helps maintain the upright structure of plants.</td>
<td>Water is an important lubricant in the eye.</td>
</tr>
</tbody>
</table>
<h2>Video: Properties of Water</h2>
<p>The <a href="http://www.amoebasisters.com/">Amoeba Sisters</a> video explores some properties of water. It's all about those hydrogen bonds.</p>
<p><iframe allowfullscreen="allowfullscreen" frameborder="0" height="360" src="https://www.youtube.com/embed/3jwAGWky98c?rel=0&amp;modestbranding=1&amp;cc_lang_pref=en&amp;cc_load_policy=1" width="640"></iframe></p>

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Role of Water in Life

Biology studies life and living organisms. Biology can be divided into different sections that cover the morphology, physiology, anatomy, behavior, and so on of living organisms.

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Discover the fundamental role of chemistry in life, explore the importance of molecules such as water, minerals, and nutrients for plant growth, and learn about the essential organic compounds, such as carbohydrates, lipids, and proteins, as well as enzymes, nucleic acids, and vitamins, and the recommended dietary allowance.


Role of Water in Life

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