Why Living Organisms 'Can't Survive Without Water' [Reading Science]

Water. Stock photo.

[Asia Economy Reporter Kim Bong-su] ‘Water’ is the most common substance on Earth, but in space, it is the most precious and peculiar substance. Unlike other substances, its unique properties play a crucial role in helping Earth's flora and fauna sustain life. Although we think we know water well, let's take a closer look at the true nature of water that we actually do not know.

First, water is a mineral. Even if we drink it, eat it, excrete it, or boil it to evaporate, it does not disappear. Just as iron ore is mined and used to make iron products without the iron component disappearing, the glass of water you are drinking now was created in prehistoric times, billions or tens of millions of years ago, and is circulating on Earth as a mineral. It is a rare substance that is hard to find even when searching the entire universe.

Second, water is a strange substance that is lighter when solid, i.e., frozen, than when in liquid form, causing it to float on water. For most substances, solidification means atoms come closer together, increasing density and weight per unit volume. However, water is the opposite. When it freezes, its volume increases by about 10%, and its density decreases, allowing ice to float on water. This is why glaciers float on water in Antarctica, and people can enjoy fishing on ice over rivers or lakes. Ice acts as a kind of insulator, raising the temperature of the water beneath and ensuring the survival of aquatic organisms.

Third, water’s ability to conduct heat well while its own temperature changes very slowly is also precious for living organisms. Water has a much higher heat capacity than other substances, requiring more heat to change its temperature by 1 degree, and its boiling point is very high at 100 degrees Celsius. Thanks to this, Earth's plants and animals can maintain stable body temperatures. Without this, humans could not enjoy saunas, and even slight cold would cause death by hypothermia. The slow temperature change of water is due to its excellent heat conduction. Its high vaporization temperature allows sweating to regulate body temperature. On a global scale, the ocean’s stable temperature acts like an air conditioner.

Fourth, water’s strong surface tension plays a decisive role in survival by driving capillary action within living organisms. Water’s surface tension is so strong that it can even float small coins. This is the cause of capillary action essential for the survival of plants and animals. When a plant’s roots absorb water, the water can rise all the way to the top due to capillary action driven by surface tension.

Fifth, water is an excellent solvent. It dissolves and adheres to all kinds of substances. This is essential for living organisms to dissolve nutrients, absorb them, and convert them into energy sources. This characteristic of water originates from its unique molecular structure. A water molecule consists of one oxygen atom and two hydrogen atoms bonded in a V-shape. The more molecules gather, the larger the volume becomes. Also, the strong bonds between oxygen and hydrogen atoms cause slow temperature changes and strong surface tension, and because water molecules have both negative and positive charges, they possess powerful solvent properties.